CA1254225A - PROCESS FOR PREPARING 1.alpha.-HYDROXYLATED COMPOUNDS - Google Patents

Abstract

ABSTRACT Novel cyclovitamin compounds of the formula wherein X is hydrogen, hydroxy, O-acyl or O-aromatic acyl, Z is hydrogen, lower alkyl, acyl or aromatic acyl and R is hydrogen or lower alkyl or a side chain of the general for-mula are prepared from the corresponding compounds of the formula via the C-3-sulfonic acid ester and then solvolyzing the ester in an alcoholic or aqueous solvent. The compounds are useful as intermediates in the preparation of the corres-ponding l.alpha.-hydroxylated vitamin D compounds which have vitamin D-like activity.

Description

lZS4$25 This invention relates to a method for preparing compounds having vitamin D-like activity and to compounds which are key intermediates in such method.
More specifically, this invention relates to a method for preparing compounds having vitamin D-like activity which contain an oxygen function at carbon 1 in the molecule.
Still more specifically, this invention relates to a method for preparing l~-hydroxylated compounds which are characterized by vitamin D-like activity via a cyclovitamin D intermediate.
It is well known that the D vitamins exhibit certain biological effects, such as stimulation of intestinal calcium absorption, stimulation of bone mineral resorption and the prevention of rickets. It is also well known that such 20 ' ~254225 biological ac-tivity is dependent upon th~se vitamins being , altered in vivo, i.e. metabolized, to hydroxylated derivatives.
¦ For example, current evidence indicates that la~25-dihydroxy-! vitamin D3 is the in vivo active form of vitamin D~ and is the compound responsible ~or the aforementioned biological effects.
The synthetic l~-hydroxyvitamin D analogs, such as 1~-hydroxyvitamin D3, and l~-hydroxyvitamin D2 also exhibit pronounced biological potency and such compounds as well as ~ the natural metabolites show great promise as agents for the l treatment of a variety of calcium metabolism and bone disorders, i such as osteodystrophy, osteomalacia and osteoporosis.
I Since l~-hydroxylation is an essential element in ¦~imparting biological activity to the vitamin D compounds and ¦,their derivatives there has been increasing interest in methods for chemically accomplishing such hydroxylation.
Except for one suggested method for the total synthesis of l~-hydroxyvitamin D3 (Lythgoe et al, J. Chem. Soc., Perkin ¦~Trans I, p. 2654 ~1974)), all syntheses of l~-hydroxylated I vitamin D compounds prior to the conception of the present iinvention involved the preparation of a l~-hydroxylated ~steroid, from whi~h, after conversion to the corresponding -hydroxy-5,7-diene sterol derivative, the desired vitamin ~D compound is obtained by well known photochemical methods.
,Thus available syntheses are multistep processes and in most ~cases are inefficient and laborious.
I A new method for introducing a hydroxyl group at the ,carbon 1 (C-l) position in the vitamin D or vitamin D derivative ~`molecule has now been found which in concept and execution ! differs radically from existing syntheses. This method, ~ - 2 -¦! l Il I

1Z~422S

which will be more fully described hereinafter, provides for ~the direct introduction of an oxygen function at C-l by allylic oxidation.
¦ In general, the method of this invention comprises ~preparing 1~-hydroxylated ~ s having the formula -...~ I
lO ,! - Ho~. OH
¦1by subjecting compounds (hereinafter referred to by the general term "cyc~ovitam ~ in8 the formula 1' Z O ~ 7 - `

;Ito allylic oxLdation, rscovering the re5u1ting 1~-hydroxy~ated : cyclovitamin D compound from the allylic oxidation reaction mixture, acylating the recovered compound and recovering the . . resulting la-0-acyl derivative, subjecting said derivative : to acid catalyzed solvolysis, recovering the desired la~
: O-acyl vitamin D compound and hydrolyzing (or reducing with ! hydride reagents) the la-0-acylated product to obtain la-j~hydroxyvitamin D compounds.
¦' In the above described process, R in the formulae represents a steroid side c~ain; most commonly a substituted ¦l or unsubstituted, or saturated or unsaturated, or substituted j. and unsaturated cholesterol side chain group and Z represents , hydrogen or a Iower alkyl or lower acyl group or aromatic acyl ~254~ S
I

¦ ~roup. Preferably R will be a cholesterol or ergosterol , side chain group characterized by the presence of a hydrogen ¦ or hydroxy group at what will be the 25-carbon (C-25) position in the desired product molecule.
~ Wherever herein and in the claims the word "lower" is 'used as a modifier for alkyl or acyl, it is intended to identify a hydrocarbon chain having from 1 to about 4 carbon jatoms and can be either a straight chain or branched chain configuration. An aromatic acyl group is a group such as ,benzoyl or substituted benzoyl. Also, in the various formulae depicted, a wavy line to any substituent is indicative of that particular substituent being in either the or S
stereoisomeric form.
More specifically, in the practice of the process of this invention, R in the formulae set forth above and those to follow, and in the claims, is preferably a cholesterol side chain group characteri~ed by the formula , o ~ R~

wherein each of Rl, R2 and ~3 are selected from the group consisting of hydrogen, hydroxy, lower alkyl, substituted lower alkyl, O-lower alkyl, substituted O-lower alkyl, and ¦ fluorine. The most preferred side chain group having the above configuration is one where Rl and R3 are hydrogen and , R2 is hydroxyl. Other preferred side chain groups are those where Rl, R2 and R3 are hydrogen, or where Rl is hydroxyl 1 and R2 and R3 are hydrogen, or where Rl and R2 are hydroxyl i and R3 is hydrogren.

I~ ' ' '_ ~ _ ' ~1 .

~5422~i 1 I Another preferred side chain group represented by R is the ergosterol side chain group characterized by the formula ~ ~ 3 'wherein each of Rl, R2 and R3 are selected from the group ~consisting of hydrogen, hydroxyl, lower alkyl, substituted ilower alkyl, O-lower alkyl, substituted O-lower alkyl, and Ifluorine, and R4 is selected from the group consisting of hydrogen and lower alkyl. The most preferred side chain I groups having the designated ergosterol side chain configuration are where Rl and R3 are hydrogen, R2 is hydroxyl and R4 is ~ methyl or where Rl, R2 and R3 are hydrogen and R4 is methyl ¦ and where the stereochemistry of R~ is that of ergosterol~
It is understood that wherever hydroxy groups occur in 'the side chain group R o~ the cyclovitamin D starting material, such groups may ~e acylated, e.g. lower acyl such as acet~l ¦ or substituted lower acyl, benzoyl or substituted benzoyl, ~ I although-such acylation is not required for success of the ¦~ process.
It is to be noted further that the side chain group R
! need not be limited to the types enumerated above. The ¦ process described in this invention is-a general one that is ¦ applicable to cyclovitamin D compounds possessing many of the common steroid side chains, e.g. the side chain of I pregnenolone, desmosterol, cholenic acid~ or homocholenic ¦ acid. In addition -to the side chain groups defined above, ¦ cyclovitamin D compounds wherein the side chain R group is ' represented for ~xample by the following structures ~CCOA~

` or ~\/~ rl ~ 5 ~/~~~ .
i.
.

12~;42~

are conveniently prepared and are suitable starting materials for the process of this invention.
, The cyclovitamin starting material for the oxidation process is conveniently prepared from a vitamin D compound i by a two-step procedure which comprises converting a vitamin D compound carryin~ a 3~-hydroxy group to the corresponding 3~-tosylate derivative and then solvolyzing this tosylate in a suitable buffered solvent mixture, such as methanol/acetone ~ containing sodium acetate, to yield the cyclovitamin product.
Sheves and Mazur ~J. Am. Chem. Soc. 97, 6249 (1975~) applied this sequence to vitamin D3, and obtained as major product a cyclovitamin D3 to which they assigned the structure shown below, i.e. 6R-methoxy-3,5-cyclovitamin D3. A minor cyclo-vitamin formed in this process was identifed as the corresponding compound with the methoxy in the 6S configuration.
i It has now been found that if the solvolysis reaction is carried out in methanol using Na~C03 buffer, a better yield of cyclovitamin product than that reported by Sheves and Maz~r can be obtained.

I It has now been found that vitamin D compounds carrying other chemically reactive substituents (e.g., side chain hydroxy 1, groups) can be converted efficiently to their cyclovitamin D
derivatives. ~or example, with 25-hydroxyvitamin D3 as the 1, starting material in the above described process 25~hydroxy-6-l~ methox~-3~s-c~clovitemin D3 is observed. The st~ucture of Ibis j,l - 6 _ . .
' .

1, ~ ~ 4~ 25 !

¦ compound is shown below, where R represents the 25-hydroxy-¦ cholesterol side chain. Similarly with 24,25-dihydroxyvitamin ¦'D3 as starting material, the above described process leads to ¦24,25-dihydroxy-6-methoxy-3,5-cyclovitamin D3 represented by the structure shown below where R represents the 24,25-dihydroxy-¦cholesterol side chain. With vitamin D2 as the starting materialthe same process sequence leads to cyclovitamin D2, also ¦represented by the structure below but where R signifies the ergosterol side chain. These cyclovitamin D compounds are new compounds.
i In analogy with the results of Sheves and Mazur cited ,earlier, the 6R-methoxy sterochemistry can be assigned to the major cyclovitamin D product obtained in these reactions, and ~to the minor constituent ~5-10%~ of the cyclovitamin product mixture the 6S-methoxy configuration. The process of this invention does not require separation of these stereoisomers, it being understood, however~ that, if desired, such separation can be accomplished by known methods, and that either C~ -epimer ican be used although not necessarily with the same process jefficiency. For these reasons stereochemical configuration ~at C-6 of the cyclovitamin D compounds is not designated in ¦ the structures of the speciPication and the claims.

CH30 [~

..
Il .

i2542:i:5 , By appropriate choice of suit~ble reagents or conditions the process of this invention will yield cyc~ovitamin D

' I

where Z represents hydrogen, alkyl or acyl, and R can represent any of the side chain structure types defined earlier. For example, if ethanol instead of methanol is used in the solvolyzing medium, a cyclovitamin of the structure shown above is ob-tained, where Z represents ethyl. It is evident that other 0-alkylated cyclovitamin D products can be obtained by the use of the appropriate alcohol in the reaction medium.
Similarly a solvolysis reaction medium composed of solvents containing H20, such as acetonelH20, or dioxanelH20, in the presence of an acetate salt or other buffering agent yields the corresponding cyclovitamin D compound of the formula shown above where Z is hydrogen. Sheves and Mazur [Tetrahedron Letters tNo. 34) pp. 2987-2990 (19762] have in fact prepared 6-hydroxycyclovitamin D3; i.e. the compound represented by the structure above where`Z is hydrogen and R represents the cholesterol sidechain, by treating vitamin D3 tosylate with aqueous acetone buffered with KHC03.
It has now been found that a 6-hydroxy cyclovitamin, if desired, can be converted to the correspond;ng acyl derivative ¦!
_ I . ".
- B -~Z~4225 ~i.e. Z = acyl, such as acetyl or benzoyl) by acylation using standard conditions (e.g. acetic anhydride/pyridine~.
The acylated cyclovitamin D of the structure shown above, ¦ with Z representing acetyl, can also be obtained as a minor llproduct, when the solvolysis reaction is carried out in a ¦ medium of dry methanol containing sodium acetate. The cyclovitamin D compound where Z represents methyl is a preferred starting material for subsequent reactions.
In the process of this invention the allylic oxidation 'is normally carried out in a suitable solvent, such as, for example, CH2C12, CHC13, dioxane or tetrahydrofuran, utilizing ¦ selenium dioxide as the oxidizing agent. Because of the nature of this oxidation reaction, it is preferable that it be carried out at room temperature or lower temperatures.
-The oxidation reaction is also most advantageously conducted i ¦ in the presence of a hydroperoxide, for example, hydrogen ,peroxide or an alkyl hydroperoxide such as tert-butyl hydro-lperoxide. The oxidation product, i.e. the la-hydroxycyclovitamin IID compound~ is readily recovered from the reaction mixture ¦,by solvent extraction (e.g. ether), and is conveniently further purified by chromatography.- Other allylic oxidants jcan be used if desired, it being understood that with such ~other oxidants variation in product yield may be encountered ¦'and that adjustment of the conditions under which the oxidation ¦reaction is carried out may have to be made, as will be 'evident to those skilled in the art. The products resulting from allylic oxidation of cyclovitamin D compounds of the ~,structure shown abDve where Z represents lower alkyl te.g.
methyl) are readily illustrated by the following formula l' ' ..................................................... .
_ g _ !1l ~ ~5~225 .1 . 1, 1~ ~~ l where R represents any of the side chain structures defined ~ earlier, and Z represents lower alkyl te.g. methyl).
; Oxidation of the cyclovitamins by the process of this , invention results in the formation of l-hydroxycyclovitamins ; possessing the l~-stereochemistry which ;s desired, i.e., ; the stereochemistry of biologically active l-hydroxyiated ¦' vitamin D metabolites. The positional and stereochemical selectivity and the remarkable efficiency of the oxidation process is both novel and unexpected and all l~-hydroxy-cyclovitamins disclosed are new compounds.
Minor products resulting from selenium dioxide oxidation , of cyclovitamin D compounds are l-oxocyclovitamin D derivatives I of the following structurè
. R .

I,. . Z~ ~ . .

where Z represen-ts lower alkyl and R represents any of the side chain groups defined ëarlier. These l-oxocyclovitamin 2s4æs 1. .. .
D derivatives are readily reduced by hydride reagents (e.g.
LiAlH4 or NaBH4 or equivalent reagents) to form predominantly l~-hydroxycyclovitamin D derivatives of the formula illustrated i~previously. The facile reduction of l-oxocyclovitamin D
¦'compounds and especially the predominant form~tion of l-hydroxy-cyclovitamin D compounds possessing the l~-stereochemistry ! is an unexpected finding, since mechanistic arguments-would have predicted approach of the hydride reducing agent ~rom ¦the l~ss hindered side of the l-oxocyclovitamin D molecule which would lead to the predominant function'of the l~-hydroxy-cyclovitamin epimer.
The acylation of the recovered l~-hydroxycyclovitamin D
compound is conveniently accomplished by standard methods with well-known acylating reagents, acetic anhydride beir.g . one example, in a suitable solvent, e.g. pyridine, and is normally conducted at room temperature over a period of several hours, e.g. overnight. The product of acylation is the corresponding l-O-acylcyclovitam~n D compound, which is I conveniently recovered in a purity sufficient for further reactions by solvent (e.g. ether)'extraction from the medium ; ! with subsequent evaporation of solvents.
Any primary or secondary hydroxyl groups present in the side chain (R) of t~e'l~-hydroxycyclovitamin D compound can be expected to be acylated also under these conditions~ If complete acylation of tertiary hydroxy groups (e.g. the 25-hydroxy-group) is desired, more vigorous acylating conditions are normally required, e.g. elevated temperatures (75-100C). It is advisable in such cases to conduct the I reaction under a n:itrogen atmosphere to avoid decomposition I of labile compounds. Products of such acyla-tions can be llustrated ~y the formula ¦

-11- 1~

1. ` ~ I
. . I
%~ l i ~
'where Y represents a lower acyl group or aromatic acyl group 'and Z represents lower alkyl and lwhere R can represent any ¦ of the steroid side chains defined earlier in this specification, ¦ it being understood that secondary or primary hydroxyl groups originally present, will now occur as the correspond-ing 0-acyl substituent, and any tertiary hydroxy group originally present, may be hydroxy or 0-acyl depending on the condition chosen.
; ¦ Conversion of the l~-0-acyl cyclovitamin to the 1~-0-acyl vitamin D derivative is accomplished by acid-catalyzed solvolysis of the cyclovitamin. Thus, warming la-0-acyl-' cyclovitamin D with p-toluenesulfonic acid, in a suitable i solvent mixture (e.g. dioxane/H20) yields l~-0-acyl vitamin D compound. Sheves and Mazur used this reaction for the `I conversion of cyclovitamin D3 to vitamin D3`~J. Am. Chem.
i l Soc. 97, 6249 ~1975)].
¦ A novel and unexpected surprising finding, not evident from the prior art, was that la-0-acyl cyclovitamin D
¦, compounds are cleanly converted and in good yield to the ' corresponding l~-0-acyl vitamin by acid solvolysis. This ,, result was completed unpredictable since the allylic la-il oxygen Punction of an la-hydroxycyclovitamin D compound ¦~ would be expected to be labile to the solvolysis conditions.

I - 12 - `
~ .
i 12~422S

Direct solvolysis of the l~-hydroxycyclovitamin D
can be accomplished in the presence of organic carboxylic acids, e.g., acetic, formic, with subsequent recavery of the corresponding 3-O-acyl la-hydroxyvitamin D derivative and conversion of such derivative to the corresponding hydroxy compound.
It is also important that any tertiary or allylic alcohol functions that may occur in the side chain be pro-tected as the corresponding acylates or other suitable, acid-stable protecting group. The product l~-O-acyl vitamin D is readily recovered from the solvolysis mixture by solvent extraction and is further purified by chromatography. The solvolysis reaction yi~lds both la-O-acyl vitamin D possessing ; the naturalS,6-cis double bond geometry, and the corresponding l~-O-acyl vitamin D with a 5,6-trans geometry, in a ratio of ca. 5:1. These products are readily separated by solvent extraction and chromatography to yield in pure form l~-O-acyl vitamin D product of the general formula illustrated below ~as well as, if desired, the corresponding 5,6-trans-isomer~, R
., ~
' . Il HO ~ OY
where Y represents a lower acyl group (e.g. acetyl) or aromatic acyl group (e.g. benzoyl) and where R represents any of the steroid side chains defined earlier, it being understood that all hydroxy functions are present as their corresponding O-acyl derivatives.

I ~2s4225 .~, I
! I
la-O-acyl vitamin D derivatives are readily converted j to the desired l-hydroxyvitamin D compounds by hydrolytic ¦ or reductive removal of the acyl protecting group. The ¦, specific method chosen would depend on the nature of the compound, in particular also the nature of the side chain R
group and its substituents. It is understood for example 'that hydride reduction would not be employed, if simultaneous ~reduction of another function susceptible to reduction, e.g.
1 ketone or ester, is to be avoided, or else such functions ¦ would be suitably modified prior to reductive removal of acyl groups. Thus, treatment of the acylated compound with a suitable hydride reducing agent te.g. lithium aluminum hydride) yields the corresponding la-hydroxyvitamin D
compound. Similarly mild basic hydrolysis (e.g. KOH/MeOH~
~converts the acylated compound to the desired la-hydroxy ¦,derivative, it being understood that in cases where the side ~chain carries sterically hindered (~.g. tertiary~ O-acyl l~groups, more vigorous conditions (elevated temperatures, ~
¦~prolonged reaction times) may be required. The la-hydroxyvitamin j,D compound prepared by either method, is readily recovered j~in pure form by solvent extraction (e.g. ether~ and chroma-tography and/or crystallization from a suitable solvent.
¦~ An alternative and novel method for converting the la-¦ O-acyl cyclovitamin D compounds to corresponding vitamin D
¦Iderivatives cons1sts of acid-catalyzed solvolysis of the cyclovitamin compound in a medium consisting of an organic ~'acid te.g. acetic acid, formic acid) or of an organic acid with a co-solvenl, such as acetone, or dioxane, if required !Ifor solubilizing the cyclovitamin. It is a particular ! advantage of this method that if the side chain group R

¦'contains any tertiary hydroxy groups (e.g. the 25-hydroxy I, .

~Z~ii42~S

j group) protection of such functionalities, e.g. as their acyl derivatives, is not necessary. Thus, by way of example, solvolysis of l~-O-acetoxyvitamin D3 in glacial acetic acid yields la-acetoxy vitamin D3 3B-acetate, as well as some of the corresponding 5,6-trans-compound tproduct ratio ca.
¦~ 3:1). These products can be separated by chromatography or ¦ the mixture can be hydrolyzed uncler basic conditions ~such as KOHtMeOH) to yield l~-hydroxyvitamin D3 and the corresponding l-hydroxy-5,6-trans-vitamin D3, which can then be separated ~ by chromatography. This method can be applied to any 1~-0-acyl cyclovitamin D compound possessing any of the side I chain groups R defined earlier in this specification.
Even more advantageously, solvolysis of l-O-acyl ¦~cyclovitamins can be carried out in formic acid or formic ! acid plus a suitabie co-solvent such as dioxane. This ¦ process leads to the formation of l~-O-acyl-vitamin D 3~-formate dcrivatives, illustraee tbe Folloving formula ~where Y is a lower acyl group (preferably not formyl) or ¦~aromatic acyl group and R represents any of the side chain groups defined earlier. Again the corresponding 5~6-trans ~compound is formed also as a minor product. Since the 3~-0-j ~ormyl group is very readily hydrolyzed under conditions I where the l~-O-acyl group is not affected (e.g. by treatment ¦! - 15 -:l2542:~5 1.
:
¦ with potassium carbonate in a few minutes, as shown by the specific Examples), the above miY.ture of 3-0-formyl products are readily converted to la-0-acyl vitamin D and its corresponding i 5,6-trans isomer. This mixture can be conveniently separated at this stage by chromatographic methods to yield pure 1-0-acyl vitamin D and the corresponding 5,6-trans-1~ 0-acyl i vitamin D which can now separately be subjected to bas~c hydrolysis, or to reductive cleavage of the acyl group to j yield l~-hydroxyvitamin D compound, and 5,6-t'r'ans-1-- ' 10 I hydroxyvitamin D compound.

¦ Another novel procedure for the conversion of la-0-acyl ' cyclovitamin derivatives to la-0-acyl-3~-formyl vitamin D
compounds of the formula illustrated above involves use of "crown 'ether" catalysts. For example, a two-phase system consisting of formic acid and a hydrocarbon (e.g. hexane/benzene~
solution of l-0-acyl cyclovitamin D containing a suitable crown ether (e.g. 15-crown-5~ Aldrich Chemical Co., Milwaukee) and formate ion, converts the l~-0-acyl cyclovitamin to the ' l~-O-acyl-3~-0-formyl vitamin D derivative in good yield.

¦ The corresponding 5,6-trans isomer is formed as a minor , product and is conveniently separated by chromatography.
Ii A further variation of the methods just described ¦I consists of converting a l~-hydroxycyclovitamin D compound ¦ to the corresponding l~-0-formyl derivative (e.g. by means I of acetic-formic anhydride, in pyridine) reprecented by the following formula ~ ' 30 1' zo~l ¦' ~ C H

li - 16 -11 . I
l! ¦

1 ........................................................... I
li ~2542~
I` , where R represents any of the side chain groups defined herein before and Z represents lower alkyl, and subjecting this intermediate to solvolysis in glacial acetic acid, as previously described, to obtain, l-formyloxy vitamin D ~-acetate and as a minor product the corresponding 5,6-trans isomer.
jRemoval of the formyl group, as described above, yields la-Ihydroxyvitamin D 3-acetate and its 5,6-trans isomer which lare conveniently separated at this stage by chromatography ¦and then separately subjected to hydrolysis or reductive ,cleavage of the acetates to yield a pure la-hydroxyvitamin D
compound and its 5,6-trans isomer.
Ii The allylic oxidation process of this invention can also ¦ be applied to cyclovitamin D compounds bearing 6-hydroxy or ¦l6-0-acyl groups. Thus, cyclovitamin D compounds of the followin~ structuDe ~

! where ~ represents hydrogen and R represents any of the I sidechain groups defined herein before can-be oxidized at !~ carbon 1 by the ally~ic oxidation process of this invention ¦ to yield la-hydroxy-6-hydroxycyclovitamin D compounds and 1-oxo-6-hydroxycyclovitamin cyclovitamin D compounds. Under the oxidation conditions previously described, some cycloreversion .l of the la-hydroxy-6-hydroxycyclovitamin D compound to a ! mixture of 5~6-cis and 5~6-trans-la-hydroxyvitamin D compounds 1 also occurs. All products are readily recovered from the oxidation mixture by chromatography. The la-hydroxy-6-hydroxycycyclov;tamin D compounds obtained by allylic oxidation `;

j can ~e acylated (e.g. acetylated) by the standard process , described previously and the resulting 1,6-diacyl cyclovitamin ! D intermediates are readily converted by ac;d solvolysis as ¦ discussed above to 5,6-cis and 5,6-trans-1~-0-acyl vitamin D
compounds which are easily separ~ted by chromatography.
Hydrolysis (by known methods) of the l-O-acyl derivatives leads to the desired l~-hydroxyvitamin D products and their ~5,6-trans isomers respectively. The l-oxo-6-hydroxycyclovitamin ~D products are readily reduced by hydride reagents the la-hydroxycyclovitamin derivatives.
Similarly, cyclovitamin D compounds of the structureshown above where Z represents acyl (e.g. acetyl, benzoyl~
'and R represents any of the sidechain groups previously ¦defined, can be converted by the sequence of allylic oxidation, acylation, acid solvolysis, and finally hydrolysis of the ¦~acyl groups as described for the case of the 6-hydroxy analogues ¦to la-hydroxyvitamin D products and their corresponding 5,6-,trans isomers.
I A further noteworthy and unexpeeted finding made i~ the jcourse of this invention is the discovery that la-hydroxyvitamin tD compounds are readily and efficiently converted to la-hydroxy-~cyclovitamin D compounds by solvolysis of the 3~-tosylates (or mesylates~ of la-hydroxy- or la-O-acyl vitamin D derivatives.
I~For example, la-acetoxyvitamin D3 3-tosylate, upon solvolysis ¦tusing conditions described herein before, e.g., heating in methanol solvent containing NaHC03, yields la-hydroxy-6-methoxy-3,5-cyclovitamin D3. Oxidation of this product te.g. with MnO2 in CH2C12 solvent) yields the corresponding 1-oxo-6-methoxy-1~3,5-cyclovitamin D3 analog as described in the specific examples.
~ In the following examples, which are intended to be illustrative only, the numbers identifying particular products, e.~. 3a for la-hydroxycyclovitemin D3, correspond to the i - 18 -! numbers designating the various structures for such products as set forth below.

o D~" CH., J Cl13 ;/
I, 1 2 3 lC ' L

OAc ~o - OA. HO "- Olt I a: R =

I b: R = ~H

c: R = ~ .-ll d: R = ~OH

30 1' :

I - 19 _ ., I!

:L~54225 . CH3~ Z~IJ ~o~l H
~' 7 8 Z = H 10 10 ¦ `- 9 Z = Ac C~O~ C~

C110 AeO''~OCHo - ! 11 12 - 1I b: R - ~----~ H

c: R = = ~

d: R = ~OH

ii ' " , . . .
_ 20-12542~5 Ex~ple 1 lu~Hydroxycyclovita~in D3 r3a) and l-oxo-cyclovita~in_ 3 (7a):
' To a stirred suspension of 1.4 mg (1.2 x 10 5 moles) of SeO2 in 1.0 ml of dr~- CH2C12 is added 7 ~1 ~5.1 x 10 5 moles~ of a 70% solution of tert.
utyl hydrop~roxid2 (t-BuOOH). After stirrin~ for 25 ~in a solution of 9 mg (2.3 x 10 5 moles) of 3,5-cyclovita~in D3 (compound 2a, prepared from vitamin ¦D3 ~la) by the method of Sheves ~ Mazur, J. Am. Chem. Soc. 97, 6249 (1975)~
in 0.5 ml of CH2C12 is added drop~ise. The mixture is stirred at room temper-¦,ature for an addi~ional 25 ~in. Then 2.0 ~1 of 10% NaOH iR added, and this ¦-resulting mixture is diluted with 15 ml of diethylether. The organ-fc phase ; ¦is fieparated and washed successively with 10~ NaOH (2 x 10 ml), H2O (2 x 10 Iml), sat. FeS04 t3 x 10 ~1), and sat. NaCl (15 ml); and then dried over ¦MgSO4. Removal of solvent in vacuo yields a crude oily product that after ! chromatograph7 on a silica gel thin layer plate (10 x 20 cm, 750 ~m) developed ¦in 30% ethylacetate: Skellysolve B yields 4.5 mg (43% yield) of l~-hydroxy-- !3,5-cyclovitamin D3 (3a): mass spectrum: (m/e) 414(30), 382~70), 341(35), 269(20), 247(45), 174(25), 165(30), 135(65); NMR, ~, ~.53 (3~, s, 18-~3), '0.61 (2H, m, 4-H2), 0.87 (6H, d, 26-H3 and 27-H3~, 0.92 (3H, d, 21-H3), 3-26 (3E, s, 6-OCE3), 4.18 (lH, d9 J=9.0 ~z, 6-H), 4.22 ~lH, m, l-H), 4.95~(1H, d, IJ=9 Hz, 7-H), 5.17 (lH, d, ~=2.2 ~z, l9(Z)-H), 5.25 (lH, d, J=2.2 Hz, l9(E~-.H), ~ s a minor component 2.0 mg (19Z yield) of l-oxo-cyclovitamin D3 (7a) was isolated from the reaction ~ixture: ~ass spectrum: ~m/e) 412 t40), ~380 (50), 267 (15), 247 (23), 135 (50)9 133 (100); NMR, ~, 0.49 (3H, s, 18-H3), IQ-58 (2H, m, 4-H2), 0.87 (6H, d, 26-E3 and 27-~ ), 0.93 (3H, d, 21-E3), 3.30 ¦~3~, s, 6-OCH3), 4.07 (lE, d, J=9.0 Hz, 6-H), 5.02 (lE, d, ~=9.0 Hz, 7-H), !5.62 (lH, s, l9(Z)-~), 6.04 (lH, s, 19(E)-H); UV 248 (4,000).
l - - .
Example 2 ~l~-Acetoxy-cyclovitamin D3 (4a):
Compound 3a (1.5 m,g) is dissolved in 200 ~1 of dry pyridine and 50 ~1 of acetic anhydride. The reaction is ~ept at room temperature overnight, then * Trade Mark 21 ! diluted with 5 ml of sat. NaHC03 solution. This solution is extracted with .three 5 ml portions of ether and the organic extracts are washed with H20 (2 x 10 ml), dried over MgS04, and the solvent is removed in vacuo to give compound 4a: NMR, ~, 0.53 (3H, s, 18-H3), 0.69 (2H, m, 4-H2), 0.87 (6H, d, 26-H3 and 27-H3)~ 0.92 (3H~ d~ 21-H3)~ 2.10 (3H~ s~ l-OAc), 3.26 (3H~ 8~ 6-iOCH3), 4.18 (lH, d, J=9.2 Hz~ 6-H), 4.98 (lH~ d, J=9.2 Hz~ 7-H~, 4.98 (lH~ d, ¦J=2.1 Hz, l9(Z)-H)~ 5.23 (lH, m~ l-H), 5.25 (lH, d~ J=2.1 Hz, l9(E)-H).

¦ Example 3 ~ Hydroxyvitamin D3 (6a):
A solution of 1.3 mg of (4a) in 0.5 ml of a 3:1 mixture of 1,4-dioxane and H20 is heated to 55~, 0.2 mg of p-toluenesulfonic acid in 4 ~1 of H20 iS
,added and heating is continued for 0.5 hr. The reaction is then quenched with 2 ml of sat. NaHC03 and extracted with two 10 ml portions of ether. The ,organic extracts are dried over MgS04 and the solvent removed in vacuo. The crude product is then applied to a 10 x 20 cm silica gel plate developed in ~i30% EtOAc: Skellysolve B to yield 400 ~g of product 5a: UY, ~maX 264 nm;
,mass spectrum, m/e 442 (M , 75)~ 382 a 0~, 269(15~ 134(100?; NMR~ ~ 0.52 ¦(3H, s~ 18-H3)~ 0.86 (6H~ d~ J=5.5 HZ~ 26-H3 and 27-H3)~ 0.91 (3H~ d~ J=5.9 IH~, 21-H3), 2.03 (3H, s, l-OCOCH3), 4.19 (lH, m, 3-H), 5.04 ~lH, d~ J=1.5 Hz~
jl9(Z)-H)~ 5.31 (lH, m(sharp)~ l9(E)-H)~ 5.49 (lH~ m, l-H~ 5.93 (lH~ d~
IJ=11. 4 HZ~ 7-H), 6 . 37 ~lH~ d, J=11. 4 Hz, 6-H).

i Product 5a is taken up in 0.5 ml of ether and treated with excess LiAlH4.
The reaction is quenched with sat. NaCl solution and product is isolated by ~filtration and evaporation of the solvent in vacuo. The slngle product (6a~
,co-chromatographs with a standard sample of la-hydroxyvitamin D3 in 97:3 ,CHC13:CH30H (l~-hyclroxyvitamin D3 Rf = 0.10, l~-hydroxyvitamin D3 Rf = 0.15, ,reaction product (6a), Rf ~ 0.10). This product possesses ~max = 264 nm and a mass spectrum and nmr speCtrum identical to that of authentic l~-hydroxy-vitamin D3-~ -Il - 22 -~L2542ZS
Example 4 25-Hydroxycyclovitamin D3 (2b):
A solution of 100 mg of 25-hydroxyvitamin D3 (lb) and 150 mg of p-, toluene-solfonyl chloride in 0.5 ml of dry pyridine is allowed to react for 24 hr at 3, and is then quenched with 5 ml of sat. NaHCO3. The aqueous l.phase is extracted with ether (2 x 10 ml~ and the ether extract is washed ¦t~ith sat- NaHC03 (3 x 10 ml), 3% HCl (2 x 10 ml), and H2O (2 x 10 ml) and then dried over MgSO4. The solvent is removed in vacuo and the crude !,residue t25-hydroxyvitamin D3 3-tosyla~e) is taken up in 1.5 ml of anhydrous ¦methanol and 0.3 ml of anhydrous acetone~ 170 mg ~8 eq.~ of NaOAc is added ¦'and the solution is warmed to 55 for 20 hr. The mixture is cooled, diluted ~ith 10 ml of H2O and extracted with 3 x 10 ml of ether. The organic extracts ~are washed with three 10 ml portions of H20, dried over MgS04, and the solvent is removed in vacuo. This crude residue is applied to a 20 cm x 20 cm silica gel TLC plate (750~m thick) which is developed once in a Skellysolve B:ethyl acetate (8:2) system to yield 48 mg (45Z overall yield from lb~ of (2b): mass spectrum, m/e: 414 (M , 40), 399(10), 382(80), 253(50), 59(100);
iN~ , 0.53 (3H, s, 18-~3), 0.74 (2H, m, 4-H2), 0.94 (3~s d, J=6.2 H2~ 21-¦~H3), 1.21 ~6H, s, 26-H3 and 27-H3), 3.25 (3H, s, 6-OC~), 4.16 (1~, d, J=9.2 IHz, 6-H), 4.~9 (lH, m(sharp), l9(Z)-H), 4.99 (lH, d, J-9.3 Rz, 7-H)s 5.04 i~lH, m(sharp), l9(E)-H).
Example 5 i1,25-Dihydroxycyclovitamin D3 (3b) and:l-oxo-25-hydroxycyclovitamin D~ (7b):
j A mixture of 2.45 mg (0.5 eq.) of SeO2, 14 ~1 (2 eq.) of t-BuOOH and 1.2 `ml of dry CH2C12 is allowed to react at room temperature for 30 min. A
solution of the cyclovitamin (2b) in 0.5 ml of C~2C12 is added dropwise to ¦this oxidizing medium, and the reaction is continued for 15 min. The reaction ; I;is then quenched with 2.0 ml of 10X NaOH and diluted with 20 ml of diethyl ~., 'Il, ' ' , .

ll Il. ' , ~1 254~22S

ether. The organic phase is separated and washed successively wlth 10% NaOH, , H2O, sat. FeS04 solution, sat. NaHC03, and again with H~O, and then dried I over MgSO4. The solven~ is removed in vacuo and the crude residue is applied to a silica gel thin layer plate (20 cm x 20 cm, 750~mthick), which is ~developed in a Skellysolve B:ethyl acetate (6:4) system to yield 11 mg (53%
Iyield) of (3b): mass spectrum: m/e 430(M+, 15), 412(12). 380(35~, 269(10), ¦59~100); NMR, ~, 0.53 (3H, s, 18-H3), 0.61 (2H, m, 4-H2), 0.93 (3H, d, J=6.2 jHz, 21-H3), 1.21 (6H, 5, 26-H3 and 27-H3), 3.25 (3H, s, 6-OCH3?, 4-17 (lH, d, J=9.2 Hz, 6-H), 4.20 (lH, m, l-H), 4.95 (lH, d, J=9.2 Hz, 7-H~, 5.19 (lH, d, ~J=l.9 Hz, l9tZ)-H), 5.22 (lH, d, J=l.9 Hz, l9(E)-H). As a minor component 1-oxo-25-hydroxycyclovitamin D3 (7b) was isolated (15~) from the reaction .mixture. Mass spectrum: m/e 428 (M ).

- Example 6 '1~,25-Dihydroxycyclovitamin D3-1,25-diacetate (4b-25-OAc):
A solution of 7 mg of (3b) in 200 ~1 of-dry pyridine is treated with ,10 ~1 of acetic anhydride. The syseem is flushed with N2 and heated to 97 ¦for 16.0 hr. After cooling, the mixture is diluted with 5 ml of sat. NaHC03.
The aqueous mixture is extracted with two 10 ml portions of ether and the ¦lorganic phase is washed successively with two 10 ml portions o~ sat. ~aHC03, liand then with 10 ml of H20. After drying over MgSO4, the solvent and residual pyridine are removed by azeotropic distillation with benzene in vacuo. The crude product is then applied to a silica gel thin layer piate (10 cm x 20 jcm, 750~m thick) daveloped in Skellysolve B:ethyl acetate (8:2) to yield 6 mg (72Z) of the diacetate (4b,25-OAc) and 1.2 mg of the corresponding 3-acetoxy-25-hydroxy derivative.

~', ' .
.ji ' . ' .
!l . . .
!i~
, ' .

- ~4 -I!
Il `~25~225 Example 7 jl,25-Dihydroxyvitamin D3-1,25-diacetate (5b,25-OAc):
! To 3.8 mg of t4b,25-OAc), dissolved in 400 ~1 of dioxane:H2O (3:1~ and ,warmed to 55~, is added 8 ~1 of a solutiQn of p-tvluene sulfonic acid in }l2O
'and heating is continued for 10 min. The reaction is quenched with sat.
NaHC03 and extracted with two 10 ml portions of ether. The ether solution is washed with two 10 ml portions of H~O and dried over MgS04. The solvent is ,removed in vacuo, and the residue is applied to a silica gel thin layer plate !~5 x 20 cm, 250~m thick) which is developed in Skellysolve B:ethyl acetate ¦!(8:2) to yield 1.8 mg (45Z) of (5b,25-OAc): W; 1 ax 265 nm; mass spectrum:
m/e 500(M+~ 25), 440(55), 422(15), 398(10), 380~45), 134(100); NMR, ~, 0.52 '(3H, s, 18-H33, 0.92 (3H, d, J=6.2 Hz, 21-H3), 1.42 (6H, s, 26-H3 and 27-H3), 1-97 (3H, s, 25-OCoCH3), 2.03 (3H, s, l-OCOCH3), 4-18 (lH, m, 3-H2, 5-03 (lH9 d, J=l.l Hz, l9(Z)-H), 5.31 (lH, m(sharp), l9(E)-H), 5.49 (lH, m, l-H), 5.93 (lH, d, J=11.4 Hz, 7-H), 6.37 (lH, d, J=11.4 Hz, 6-H).

' Example 8 ~1~,25-Dihydroxyvitamin D3 (6b).
To a stirred solution of 1.0 mg of the diacetate, (5b,25-QAc~ ill 1.5 ~1 lof ether is added 0.5 ml of an ether solution saturated with LiAlH4. After 1lO miu at room temperature, the reaction is quenched with sat. NaCl solution and the salts are dissolved by addition of 3Z ~Cl. The aqueous phase is ~extracted with ether and the ether extracts are washed with H2O and dried ¦over MgSO4. Thin layer chromatography (5 x 20 cm silica gel plates, 250 ~m 'thick) using 5~ MeOH: CnC13 yields 0.6 mg (70~? of 1~,25-dihydroxyvitamin D3 ~(6b), exhibiting a W-spectrum with ~ 265 nm. The identity of-6b as ¦1~,25_dihydroxyvitamin D3 is established by direct COmpariSOD of mass and nmr spectra with those of authentic material, as well as by co-chromatography of 6b with authentic 1~,25-dihydroxyvitamin D3.

j, . .

I' ., . ' .
j, - 25 -~i ' .

iæ54225 ~xample 9 ;Cyclovitamin D2 (2c):
A solution of 100 mg of vitamin D2 (lc) and 100 mg of p-toluenesulfonyl chloride in 0.3 ml of pyridine is allowed to react for 24 hr at 3, and is then quenched with 10 ml of sat. NaHC03. The aqueous mixture is extracted with two 10 ml portions of ether and the ether extract is washed successively with sat. NaHC03 (3 x 10 ml), 3~ HCl (2 x 10 ml), and H20 (2 x 10 ml), and iS
then dried over MgS04. The solvent is rlemoved in vacuo and the crude vitamin D2-3-tosylate is taken up in 1.5 ml of anhydrous methanol and 0.3 ml of anhydrous acetone. After addition of 170 mg of sodium acetate, the solutlon is warmed to 55~ for 20 hr. After cooling, the solution is diluted with 10 ml of H20 and extracted with three 10 ml portions of ether. The organic extracts are washed with three 10 ml portions of H20, dried with MgSO4, and the solvent is removed in vacuo. The residue is chromatographed on a silica ,gel thin layer plate (20 x 20 cm, 750~m) in Skellysolve B:ethyl acetate (8:2) to yield 60 mg (59%) of (2c): mass spectrum: m/e 410 ~ , 152, 378(403, 253C40~, 119(60); N~R~ ~ 0.55 (3H~ s, 18-H3)~ 0.74 (2~ m~ 4-~22~ 0-82 and 'o.84 (6H, dd, J=4.1 ~z, 26-H3 and 27-~3), 0.91 (3H, d, J=7.0 Hz, 21 l1.02 (3H, d~ J=6.6 HZ~ 28-H3), 3.26 (3~ s~ 6-OCH3)~ 4.13 ~lH~ d~ J=9.6 ~z~
l6-H), 4.89 (lH, m, l9(Z)-H), 5.00 (lH, d, J=9.4 ~z, 7-H), 5.04 ~ m(sharp~, ~l9(E)-H), 5.20 (2H, m, 22-H and 23-H).

i Example l0 ~l-Hydroxycyclovitamin D2 (3c) and l-oxo-cyclovitamin D2 ~7C):
l A miXture of 2.7 mg of SeO2 and 13.4 ~1 of 70% t-BuOOH, in 1.5 ml of dry CH2C12~ is allowed to react for 30 min~ Compound 2c (20 mg) in 0.5 ml of ¦CH2C12 is then added dropwise~ the reaCtion is continued for 15 min~ and then quenched with 2.0 ml of 10Z NaOH. The solution is dilutèd with 15 ml of ¦ether, the ether phase is separated and washed successively with 10% NaOH~

H20, sat . FeS04 solution, sat. ~aHCO3~ and again with H2O. After drying over ¦,MgSO4~ the solvent is removed in Vacuo, and the residue is appliFd to a 1~
! - 26 -I silica gel thin layer plate (20 x 20 cm, 750l~m) which is developed once in I Skellysolve B:ethyl acetate (8 2) system to yield 9.5 mg (45%) of (3c):
mass spectrum: m/e 426(M+ SS)~ 394(75) 353(30)~ 269(40~ 135(95); N~
1 0 53 (3H S 18-H3) 0 63 (2H, m, 4-H2), 0 8~ and 0 84 (6H dd, 26-H3 and ! 27-H33~ 0 92 (3H d, J=6 0 HZ 21-H3) 1 02 (3H d, J=6 4 HZ 28-H3) 3 26 ¦I(3H S 6-OCH3) 4 18 (1H d, J=9 6 HZ 6-H), 4 21 (1H m, 1-H~ 4.94 (1H d, liJ=9.6 HZ, 7-H), 5.17 (lH, m(sharp), 19(Z)-H3, 5.19 (2H, m, 22-H and 23-H), 1l5 24 (1H m~sharp~ 19(E)-H) A second minor component isolated from the ¦lreaction mixture proved to be l-oxo-cyclovitamin D2 (7c): mass spectrum, ~10 Iim/e 424 (M~) Example 11 Hydroxycyclovitamin D2-1-acetate (4C3 TO 6 5 mg of (3C) in 300 yl of dry pyridine is added 150 yl of acetic anhydride. This solution is heated to 55~ for 1.5 hr, then diluted with 5 ml jof sat. NaHC03 and extracted with two 10 ml portions of ether. The organic ¦!extracts are washed with sat. NaHCO3, and H20, dried over MgS04 and the ilresidual pyridine and solvent is removed by azeotropic distillation with ¦-benzene in vacuo, to yield compound 4c: mass spectrum: m/e 468(M~, 40~, 408(~0), 376(65), 251(603, 135(100).

li Example 12 ¦l-Hydroxyvitamin D~-l-acetate (5c):

!~ A solution of 5.0 mg of (4c) in 400 yl of dioxane: H20 (3 1) is heated to 55; 12 yl of an aqueous solution of p-toluenesulfonic acid (50 yg/yl) is added and heating is continued for 10 min. The reaction is then quenched with sat. NaHC03 and extracted with two 10 ml portions of ether. The separated ,ether phase is washed with 10 ml of sat. NaHC03 and two 10 ml portions of 'B20, dried over MgS04, and the solvent is removed in vacuo. Preparative thin 1. ' .
i, .

. ,1-' ' ' ' .
~ 7 -Il 1;Z542~:5 layer chromato~raphy on silica gel (Skellysolve B:ethyl acetate, 8:2) gives ' 1.6 mg of 5c (32% yield); UV; ~ 265 nm; mass spectrum: m/e 454(M , 80), ! 394(80), 376(20), 269(40), 135(100); NMR, ~, 0.53 (3H, s, 18-H3~, 0.81 and 0.84 (6H, d, J=4.4 Hz, 26-H3 and 27-H3), 0.91 (3H, d, J=7.0 Hz, 21-H3), 1.01 (3H, d, J=6.7 Hz, 28-H3), 2.03 (3H, s, 3-OCOCH3), 4.18 (lH, m, 3-H), 5 03 (lH, d, J=1.5 Hz, l9(Z)-H), 5.19 (2H, m, 22-H and 23-H), 5.3 (lH, m(sharp), l9(E)-H), 5.48 (lH, m, l-H), 5.92 (lH, d, J=11.0 Hz, 7-H), 6.37 ¦' (lH, d, J=11.0 Hz, 6-H).

- I Example 13 l-Hydroxyvitamin D2 (6c):
i A solution of 1.1 mg of (5c) in 1.5 ml of ether is treated with 0.5 ml of an ether solution ~aturated with LiAlH4. After 10 min at room temperature -the reaction is quenched with sat. NaCl and the salts dissolved in 3~ HCl.
This aqueous solution is extracted with ether and the organic extracts are washed with water and dried over MgS04. TLC on 250 ~ thick, 5 x 20 cm, plates in 5% methanol:chloroform yields 0.8 mg (75% yield~ of l~-hydroxy-vitamin D2: W: ~max 265 nm; mass spectrum: m~e 412 ~ ), 394, 376, 287, ,269, 251, 152, 134 (base peak); NMR: ~, 0.56 (3H, s, 18-H3), 0.82 and 0.84 i(6~, dd, J=4.4 ~z, 26-H3 and 27-H3), 0.92 (3H, d, J=6.6 Hz, 21-H3), 1.02 (3H, j'd, J=6.6 Hz, 28-H3~, 4.23 (lH, m, 3-H~, 4.42 (lH, m, l-H), 5.00 (lH, m(sharp), ¦19(Z)-H), 5.20 C2H, m, 22-H and 23-H), 5.32 (lH, dd, J=1.4 Hz, l9(E~-H), 6.02 , d, J=l~ z, 7-H~, 6.38 (lH, d, J=11.6 Hz, 6-~). These spectral data iare in full accord with data obtained for l-hydroxyvitamin D2, prepared by an entirely different method lLam et al. Science, 186, 1038-1040 (1974~].

Example 14 Solvolysis of l-Acetoxycyclovitamin D in Acetic Acid:
; A solution of 3.0 mg of l~-hydroxycyclovitamin D3-1-acetate ( ~ in 200 ~1 of glacial acetic acid is warmed to 55 for 15 min and subsequently ~30 - 28 - .

i I

~2S422~

.
! quenched with ice-cold sat. NaHC03. The aqueous mixture is ex~racted with diethylether and the organic phase is washed with sat. NaHC03 and water, dried over MgS04, and filtered to yield a solution of 5,6-cis and 5,6-trans-l~-acetoxyvitamin D3 3-acetates (UV: ~ 267-269 nm). The dried ether solution is treated with a small amount (1.0 mg) of lithium aluminum hydride, quenched with sat. NaCl, f~ltered and the ~olvent is removed in vacuo. The crude oil is applied to a 5 x 20 cm silica gel tlc plate ¦I(250 ~mthick) which is developed in 5~ methanol:chloroform to yield 1.6 mg ,of a mixture (W , ~ 267-269 nm~ of la-hydroxyvitamin D3 (6a) and the ,corresponding 5,6-trans isomer (5,6-trans-la-hydroxyvita~in D3) in a ratio of ',3:1 as determined by NMR analysis: Characteristic resonances for the cis isomer (6a): ~, 6.38 and 6.01 (d, J=11.4 Hz, 6-H and 7-H), 5.33 (dd, J=1.5 Hz, l9(E)-H), 5.01 (sharp m, l9(Z)-H), 0.54 (s, 18-H3); for the 5,6-trans isomer: 6.58 and 5.88 (d, J=11.4 Hz, 6-H and 7-~), 5.13 (d, J-1.4 ¦.HZ, l9(E)-H), 4.98 (sharp m, l9(Z)-H), 0.56 (s, 18-~
j. The same procedure may be used to effect the cleavage of the cycloprane ¦~ring (cycloreversion) of other cyclovitamins or their C-l-oxygenated analogs.
¦,Thus heating l~-acetoxy-25-hydroxyvitamin D3 (compound 4b, no protecting group required for 25-OH function) in glacial acetic acid as described above, Iyields l-acetoxy-25-hydroxyvitamin D3 3-acetate as the major product ; ¦(plus some of the corresponding 5,6-trans isomer~ as mi~or product~ and this , 'mixture may be directly hydrolyzed (MeOH/KOH~ or subjected to hydride reduction as described above, to yield la,25-dihydroxyvitamin D3 as the ma~or product and 5,6-trans-1~,25-dihydroxyvitamin D3 as a minor product.

Example 15 .Formic acid catalyzed solvolysis of la-acetoxycyclovitamin D3:
A solution of the la-acetoxycyclovitamin D3 (4a) in dry dioxane is ¦ warmed to 55 and treated with a 1:1 solution of 98% formic acid:dioxane j (50 ~l/mg cyclovita~in) for 15 min. The reaction is then quenched with ' , .
I .

~ 42:~5 ice-water and extracted with ether. The ether extracts are washed with water, sat. NaHC03, sat. NaCl, dried over ~IgS04, and the solvent removed in vacuo. The crude product (l~-acetoxy-3~-formylvitamin V3 and its 5,6 trans isomer) is dissolved in a 1:1 solution of dioxane:methanol and an equivalent amount of aqueous ~2C03 (10 mg/100 ~ Ls added. After 5 min at room tempera-ture, the solution is diluted with water and extracted repeatedly with ether. The ether extracts are washed with water, dried over MgS04, and the ~solvent is removed in vacuo. The crude cis and trans mixture of l-acetoxy-3-Ihydroxyvitamins is then chromatographed on a 10 x 20 cm, 750~im thick silica 'gel plate in 1:3 ethyl acetate:Skellysolve B to yield the pure cis-l~-~cetoxy-vitamin D3. Basic hydrolysis, (NaOH in methanol) yields a product which is chromatographically and spectrally identical to an authentic sample of 1~-.hydroxyvitamin D3.

Example 16 ¦ ~ ln D3-tosylate:
To a suspension of 170 mg of vitamin D3-tosylate ir. 6.0 ml of anhydrous ,methanol is added 213 mg (8.0 eq.) of NaHC03. The system is flushed with ; 'nitrogen and heated to 58 for 20 hr. The reaction is then diluted w~th sat.
i~aCl solution, transferred to a separatory funnel and extracted with 2 x 10 ml portions of Et20. The organic extracts are washed with 1 x 10 ml portion ¦ of sat. NaCl and dried over MgS04. Aft'er removal of the solvent in vacuo, the oily residue is chromatographea on a 750~m, 20 x 20 cm silica gel prep plate inethyl acetate:Skellysolve B 2:8 to yield 94 mg (75%) of cyclo-¦ vitamin D3 ( ~
! Example 17 ¦~6-Hydroxy-cyclovitamin D3 (8a):

A'solution of 100 mg of vitamin D3, 100 mg of TsCl and 500 ~il of dry ,pyridine is kept at 5 for 24 ~r then diluted ~th ether and washed several Ii ~ ' ' ' ' ' ' i ' - 30 -.

~2S422~
times with sat. NaHCO3. The organic layer is dried over MgS04 and the solvent ~ is removed in vacuo. The crude D3-tosylate is suspended in 4 . O ml of ¦ acetone:H20 9:1 along with 175 mg (8 eq.) of NaHC03. The resulting mixture liis heated at 55~ overnight, diluted with sat. NaCl and extracted twice ¦with ether. The ether extract is washed once ~ith water, dried over MgS04, ¦:and the solvent removed in vacuo. Preparative TLC (20 x 20 cm, 750~m,8:2 acetates ¦Skellysolve B: ethyl /yields 55 mg of the 6-hydroxy-3,5-cyclovitamin D3 ~8a);

¦~mass spectrum, m/e 384 (M ), 366, 253, 247.
i~
I Example 18 '6-Acetoxycyclovitamin D3 (9a):
To a solution of 300 ~1 of dry pyridine and 200 ~1 of Ac2O is added 6 mg ;of 6-hydroxy-cyclovitamin D3 (8a) in 200 ~1 of pyridine. The reaction is warmed at 55 for 2.0 hr under ~2 then diluted with a large excess of ~toluene. The solution is evaporated to dryness at 40 in vacuo to yield the crude 6-acetoxycyclovitamin D3 (9a); mass spectrum, m/e 426 (M ~.

! Example 19 1 .
~,~ydride reduction of l-oxo-cvclovitamin D (7a) to 3a:
i~ -~~ - 3 --A solution of 2.0 mg of l-oxo-cyclovieamin D3 in 500 ~1 of ether'~s ~treated with 300 ~1 of ether saturated with LiAln4. After 30 min the treaction is carefully quenched by the dropwise addition of sat. NaCl. The ¦insoluble salts are removed by filtration and the filtrate is dried over MgS04. The solvent is removed in vacuo to yield 1.7 mg of a 95:5 mixture of l~-hydroxycyclovitamin D3 (3a) and the corresponding l~-hydroxycyclovitamin D3 isomer, which are separated by chromatography. Similar treatment of l-oxo-~cyclovitamin D3 with 300 ~i of lOOZ ethanol saturated with NaBH4 yields an 8:2 mixture of l~-hydroxy and l~-hydroxycyclovitamin D3 compounds (3a and its l~-epimer).

~1 .

.1~ - ' ~254~225 i I Example 20 ¦SeO~/t-BuOOH oxidation of 6-hydroxy cyclovitamin D3 (8a~:
To a stirring suspenSion of 2.0 mg of SeO2 in 1.5 ml dry CH2C12 i5 added 10 ~1 of 70~ t-BuOOH. When homogeneous~ a solution of 14 mg of 6-hydroxy 1 i of dry CH~Cl~
iis continued for 1.5 hr at room temperature. The reaction is quenched with jlO% NaOH, diluted with ether, washed with lO~ NaOH and water, dried over ~MgSO4, and the solvent removed in vacuo. The crude oily residue is .chromatographed tlO X 20 cm, 750~m,1:1 ethyl acetate.Skellysolve B) to jyield 1.5 mg (10%) 1-oxo-6-hydroxy-cyclovitamin D3: mass spectrum~ (m/e~
398 (35)~ 380 (25), 247 (25), 135 (40)~ 133 (lOQ~; 2.0 mg ~15%~ of la,6-¦laihydroxy cyclovitamin D3 (10a): maSs spectrum; (m/e~, 400 (50~ 382 (80)9 269 (20)~ 247 (40)~ 135 (80), 133 (40); and 2.0 mg (15Z) of la-hydro~y-jvitamin D3 (6a)~ and the corresponding la-hydroxy-5,6-trans isomer.

Example 21 ¦Conversion-of la,6-dihydroxy-cyclovitamin_~ (lOa~ to ~ roxyvitamin D3 ~6a):
. A solution of 400 ~1 dry pyridine, 200 yi acetic anhydride, and ~2.0 mg-of jla,6-dihydroxy-cyclovitamin D3 (10a) is warmed to 55~ for 2.0 hr. The reaCtion lis then diluted with toluene and stripped to dryness. The resulting oil ¦(la,6-diacetoxy-cyclovitamin D3) is taken up in 100 ~1 of THF and treated ,I ith 200 ~1 of 97% HC02~ for 15 min at 55'9. Dilution with sat. NaCl, extraction with ether, washing with sat. NaHCO3, drying over MgSO4, and ¦removal of the ether in vacuo gives the crude l-acetoxy-3-formate cis- and ¦ tranS- Vitamin derivatives. Selective formate hydrolysis with R2CO3 followed l by chromatography yields pure la-acetoxyvitamin D3 ~5a) ~hiCh iS converted ¦ to la-hydroxyvitamin D3 (6a) by simple ~OH/MeOH hydrolysis.
Il . , - , .
Il - 32 - -, Example 22 24(R)~25-Dihydrox~-cycl-ovitamin D3 ~2d):
To 150 ~1 of dry pyridine is added 10.4 mg of 24R,25-(OH)2D3 and 7.13 mg ~(1.5 eq.) of TsCl. The reaction is maintained at 0~ for 72 hr then diluted with sat. NaHC03 and extracted with ether. After washing the ether extract with sat. NaHCO3, drying over MgSO4, and removing the solvent in vacuo, the crude tosylate (~70X by TLC) is suspended in 2 ml of anhydrous ~eOH along with 25 mg of NaHCO3 and heated under N2 at 58~ for 20 hr. The l~eaction is then diluted with sat. NaCl and extracted with ether. The ether extracts are washed with water, dried over MgS04 and the solvent removed in vacuo. Preparative TLC (10 x 20 cm, 750 ~msilica gel, 6:4 Skellysolve B:ethyl aCetate)yields 2.5 mg of recovered 24R,25-(OH~2D3 and 4.4 mg of ~24R,25-dihydroxy-cyclovitamin D (2d). mass spectrum, (m1e~, 430 (15), 398 (65), 253 (40), 159 (45), 119 (55), 59 (100), NMR, ~, 0.55 (3H~ s, 18-H3), 0.74 (2H, m, 4-H2), 0.94 (3H, d, J=6.2 Hz, 21-H3), 1.17 (3H, s, 26-H3), 1.22 (3H, s~ 27-H3), 3.26 (3H, s, 6-OCH3), 3.34 ~lH, m, 24-H), 4.17 (lH, d, ;~J=9.0 Hz, 6-H), 4.88 (lH, m(sharp), l9(Z)-H), 5.00 ~l-H, d, J=9.O Hz, 7-H), ,5 4 ClH, m(sharp), l9(E)-H).
~ - .
I Example 23 ZO 11~,24(R),25-Trihydroxy-cyclovitamiD _3 (3d):
To a previously prepared solutioD of 1.12 mg SeO2 and 12 ~1 of 70%
It BuOOH in 1.0 ml of dry CH2C12 is added 4.2 mg of 24R,25-dihydroxy-cyclo-vitami~ D3 in 500 ~1 of CH2C12. After 30 min an additional portion of 1.12 mg e2 and 12 ~1 70X t-BuOOH, in 500 ~1 of CH2C12 is added and the reaction continued for an hour longer. The reaction is quenched with 10% NaOH, ~iluted with ether, and washea twice with 10% NaOH followed by a water wash.
The organic solution is dried over MgSO4, the solvent removed in vacuo, and the resulting oll is chro=ato3r phed on a 5 x 20 c= 250P= sllica gel plate _ 33 _ Il .
Ii li l I' I in cthyl acetate:Skellysolve B 1:1 to yield 1.6 mg of 1~,24(R),25-trihydroxy-, cyclovitamin D3 (3d): mass spectrum, (m/e), 446 (30), 414 (50), 396 (40), 269 (30), 135 (80), 59 (100); NMR, ~, 0.55 (3H, s, 18-H3~, 0.65 (2H, m, 4-H2), ,0.96 (3H, d, J=6.0 H~, 21-H3), 1.19 (3H, s. 26-H3), 1.24 (3H, s, 27-H3~, 3.28 (3~, s, 6-OCH3), 3.35 (lH, m, 24-H), 4.20 (la, d, J=9.0 Hz, b-H), 4.Z2 (lH, m, l-H), 4.97 (lH, d, J=9.0 Hz, 7-H), 5.18 (lH, m(sharp~, l9(Z)-H), 5.26 (lH, d, J=2.2 Hz, l9(E)-H). l-oxo-24(R),25-dihydroxy-cyclovitamin D3 (7d) is also isolated as a minor component (<20%).

¦~ Example 24 ,1~,24(R),25-Trihydroxyvitamin D3 (6d):
To 200 ~1 or dry pyridine and 150 ~1 of Ac2O is added 1.4 mg of lct,24R,25-.trihydroxy-cyclovitamin D3 (3d). The system is flushed with N2 and heated to 95~ for 20 hr. The reaction is then diluted with dry toluene and azeo-¦tropically distilled to dryness~ The oily product, 1,24CRj,25-triacetoxy-cyclovitamin D3 (4d-24,25-diacetate), is dissolved in 200 ~1 of TEF and added to 500 ~1 of a 1:1 solution o~ 97% HCQ2H:l~ and heated to 55 for 15 ¦.min. The cooled reaction is diluted with ether, washed with H20, sat. NaHC03, ¦~sat. NaCl, and dried over MgS04. After removal of the solvent in vacuo the ¦icrude 1,24R,25-triacetoxy-3~-formate vitamin D intermediate is dissolved in 1~200 ~1 of THF and treated with 1.0 mg K2C03 in 10 ~1 H20 and 90 ~1 MeOH for ¦~5 min at room temperature. Dilution with sat. NaCl, extraction with ether, and j~chromatography on a 5 x 20 cm, 250~m, silica gel plate in ethyl acetate:
¦~Skellysolve B 4 6 yields 1,24R,25-triacetoxy-vitamin D3. Treatment of this triacetate with LiA1~4 gives 1,24R,25-trihydroxyvitamin D3 (6d) which ¦lis identical in all respects to an authentic sample.

Example 25 'Conversion of l-hydroxycyclovitamin D3 (3a) to l-hydroxyvitamin D3 (6a) via the l-formyl intermediate (lla): ~
, A 200 ~1 portiOn of acetic anhydride is cooled to 0 and 100 ~1 of 97Z
Iformic acid is addecl slowly. The solution is brielly (15 min) heated to 50 Il - 34 -I
1i, then cooled to 0. A 100 ~1 portion of the acetic-formic anhydride is then added to a solution of 5 mg of 1~-hydroxy-cyclovitamin D3 (3a) in ¦ pyridine at 0~. After 2.0 hr the reaction is diluted with sat. NaC1, extracted j with ether, washed wlth H20, and dried over MgS04. The crude la-formyl-cyclovitamin D3 (lla) obtained after removing the solvent in vacuo is dissolved in glacial acetic acid and heated to 55~ for 15 min. Dilution with sat. NaCl, extraction with ether, and isolation of the organic products ¦igive the crude product consisting of l-formyloxyvitamin D3 3-acetate (12a) land the corresponding 5J6-trans -isomer. Treatment of the crude mixture with K2C03 in H20/MeOH followed by chromatography (5 x 20 cm, 250~m, silica gel, 3:7 ethyl acetate:Skellysolve B) yields the pure l-hydroxyvitamin D3 3-acetate ¦;and 5,6-trans l~-hydroxyvitamin D3 3-acetate, which are hydrolytically ¦ converted (KOH/MeO~) to the corresponding la-hydroxy-vitamin D3 (6a) and its 5,6-trans isomer respectively.

' Example 26 ! Cro~n e~her catalyzed cycloreversion of l~-acetoxy-cyclovitamin D3:
, A 0.5 M hexane:benzene Cl:lj solution of 15-cro~n-5 (Aldrich Chemical Co., Milwaukee) is saturated with finely divided anhydrous sodium acetate.
To 300 ~1 of this so~ution is added 11.0/ of l-acetoxy-cyclovitamin D3 ~4a) ~in 600 ~1 of dry hexanes followed by 200 ~1 of 97~ formic acid. The two-phase mixture is vortexed occasionally over 30 mln, then diluted with hexanes jand the acid layer removed. The organic phase is washed with sat. NaHC03, ~sat. ~aCl, dried over MgS04 and the solvent removed in vacuo. The crude oil llis taken up in 300 ~1 of THF and 300 ~1 of methanol and treated with 10 mg ¦ of K2C03 in 100 ~1 of H20. After 5 min at ambient temperature the reaction ¦'is diluted with sat. ~aCl and extracted with two portions of ether. The ¦ organic/is washed with H20, dried over MgS04, and the solvent removed in vacuo.

, .
!

!i. . .

22s The resulting mixture is subjected to preparative Tl,C (750 ~m, 10 x 20 cm, 75:25 Skellysolve B:ethyl acetate) to yield 5.7 mg. (54~) of la-acetoxy-vitamin D3 (5a) and 2.1 mg (20%) of 5,6-trans-1~-acetoxy-vitamin D3.
Example 27 Conversion of la-hydroxyvitamin D3 (6a? to l~-hyaroxycyclovitamin D3 (3a):
To 0.2 ml of pyridine is added 3.0 mg of la-acetoxyvitamin D3 (5a), obtained by either selective acetylation of l~-hydroxyvitamin D3 (3a)(2 molar excess acetic anhydride in pyridine, 4 hours, room temperature, followed by separation of the desired la-acetoxyvitamin D3 derivative on preparative silica gel tlc, using Skellysolve B:ethyl acetate, 3:13 or as the product from Example 2, and 6.0 my of tosylchloride. After 18 hr. at 3 the reaction is quenched with saturated NaCl solution, extracted with ether, ana the ether extracts washed repeatedly with a saturated NaHCO3 solution. After drying over MgSO4, and removal of the solvent in vacuo the crude la-acetoxyvitamin D3 3-tosylate is taken up in 3.0 ml of anhydrous MeOH bufferea with 12.0 mg of NaHCO3. The reaction mixture is heatea to 55D overnight, quenched with saturated solution of NaCl, extracted with ether and the solvent in removed in vacuo. The crude product is subjected to preparative tlc ~5.X 20 cm, 250 ~m silica gel, Skellysolve B:ethyl acetate, 3:1) to yield 2.2 mg of la-hydroxy-cyclovitamin D3 t3a) which is-identical in all respects to-the product obtained in Example 1.
Example 28 MnO2 oxidation of la-hydroxycyclovitamin D3 ~3a) to l-oxo-cyclovitamin D3 ~7a) To 1.0 ml of dry CH2C12 is added 3.0 mg of la-hyaroxycyclovitamin D3 (3a) and 35 mg of finely divided MnO2. ~See for example, Paaren et al J. Chem.
Soc., Chem. Comm. 890 (1977)~. After 2.0 hr. the reaction mixture is filtered through Celite to yield, after preparative tlc (5 x 20 cm. 250 ~m, silica gel, Skellysolve B:ethyl acetate), 2.6 mg of l-oxo-cyclovitamin D3 ~7a) identical in all respects to the product described in Example 1.

* Trade Mark ~4æs ~' Example_29 Direct solvolysis of la-Hydroxycyclovi-tamin D compounds 3.8 ml of glacial acetic acid is added to 380 mg of 1~-hydroxycyclovitamin D3 and the solution warmed for 10 min. at 60.
After cooling the mixture is added to a stirring solution of ice/NaHCO3. The neutralized aqueous solution is extracted with diethyl ether, the combined organic extracts washed once with water and dried over MgSO4. The crude product after solvent re-moval is chromatagraphed on a 1.5 x 60 cm column, of 50 g of neutral silica gel eluted with 100 ml of 4%, 100 ml of 8%, 100 ml of 12%, and 400 ml of 16~ EtOAc/Skellysolve B. The desired 1~-hydroxyvitamin D3 3-acetate isomer elutes before la-hydroxy-5,6-trans-vitamin D3 3-acetate; 175 mg of la-hydroxyvitamin D3 3-acetate is obtained; UV: ~maX264 nm; MS(m/e)442(M ,8), 382(70), 364(15), 269(20), 134(100).
Hydrolysis of la-hydroxyvitamin D3 3-acetate (10% NaOH/
MeOH, 2hr. RT)yields l~-hydroxyvitamin D3.

Claims (32)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A process for the preparation of a compound hav-ing the general formula wherein X is hydrogen, hydroxy, O-acyl or O-aromatic acyl, Z is hydrogen, lower alkyl, acyl or aromatic acyl and R
is hydrogen or lower alkyl or a side chain of the general formula or wherein each of R1, R2 and R3 is selected from the group consisting of hydrogen, hydroxy, lower alkyl, O-lower alkyl O-acyl, O-aromatic acyl and fluorine, R4 is hydrogen, or lower alkyl, each of R5 and R6 is selected from the group consisting of hydrogen, hydroxy, O-acyl, O-aromatic acyl, O-alkyl and fluoro, or where R5 and R6 when taken together form a double bond, R7 is hydrogen, hydroxy, lower alkyl, or O-lower alkyl and n is an lnteger from 1 to 4, with the proviso that when Z is methyl, all of X, R1, R2, R3, R4, R5, and R6 cannot be hydrogen, which comprises converting a vitamin D compound of the gene-ral formula wherein R and X are defined as above, to the corresponding C-3-sulfonic acid ester and solvolyz-ing said ester in an alcoholic or aqueous solvent to obtain a compound of the general formula wherein R, X and Z are as defined as above.

2. The process of claim 1 wherein the vitamin D
compound utilized as the starting material is vitamin D3.

3. The process of claim 1 wherein the vitamin D
compound utilized as the starting material is vitamin D2.

4. The process of claim 1 wherein the vitamin D
compound utilized as the starting material is 25-hydroxy-vitamin D3.

5. The process of claim 1 wherein the vitamin D
compound utilized as the starting material is 25-hydroxy-vitamin D2.

6. The process of claim 1 wherein the vitamin D
compound utilized as the starting material is 24,25-dihydroxy-vitamin D3.

7. A compound having the general formula wherein X is hydrogen, hydroxy, O-acyl or O-aromatic acyl, Z is hydrogen, lower alkyl, acyl or aromatic acyl and R is hydrogen or lower alkyl or a side chain of the general for-mula wherein each of R1, R2, and R3 is selected from the group consisting of hydrogen, hydroxy, lower alkyl, O-lower alkyl, O-acyl, O-aromatic acyl and fluorine, R4 is hydrogen, or lower alkyl, each of R5 and R6 is selected from the group consisting of hydrogen, hydroxy, O-acyl, O-aromatic acyl, O-alkyl and fluoro, or where R5 and R6 when taken together form a double bond, R7 is hydrogen, hydroxy, lower alkyl, or O-lower alkyl and n is an integer from 1 to 4, with the proviso that when Z is methyl, all of X, R1, R2, R3, R4, R5, and R6 cannot be hydrogen, when prepared by the process of claim 1.

8. A vitamin D3 compound, as defined in claim 7, when prepared by the process of claim 2.

9. A vitamin D2 compound, as defined in claim 7, when prepared by the process of claim 3.

10. A 25-hydroxy-vitamin D3 compound, as defined in claim 7, when prepared by the process of claim 4.

11. A 25-hydroxy-vitamin D2 compound, as defined in claim 7, when prepared by the process of claim 5.

12. A 24,25-dihydroxy-vitamin D3 compound, as de-fined in claim 7, when prepared by the process of claim 6.

13. A compound having the general formula wherein X is hydrogen, hydroxy, O-acyl or O-aromatic acyl, Z is hydrogen, lower alkyl, acyl or aromatic acyl and R is hydrogen or lower alkyl or a side chain of the general formula wherein each of R1, R2, and R3 is selected from the group consisting of hydrogen, hydroxy, lower alkyl, O-lower alkyl, O-acyl, O-aromatic acyl and fluorine, R4 is hydrogen, or lower alkyl, each of R5 and R6 is selected from the group consisting of hydrogen, hydroxy, O-acyl, O-aromatic acyl, O-alkyl and fluoro, or where R5 and R6 when taken together form a double bond, R7 is hydrogen, hydroxy, lower alkyl, or O-lower alkyl, and n is an integer from 1 to 4, with the proviso that when Z is methyl, all of X, R1, R2, R3, R4, R5, and R6 cannot be hydrogen.

14. A vitamin D3 compound, as defined in claim 13.

15. A vitamin D2 compound, as defined in claim 13.

16. A 25-hydroxy-vitamin D3 compound, as defined in claim 13.

17. A 25-hydroxy-vitamin D2 compound, as defined in claim 13.

18. A 24,25-dihydroxy-vitamin D3 compound, as defined in claim 13.

19. 1.alpha.-Hydroxycyclovitamin D3 having the formula

20. l.alpha.-Acetoxycyclovitamin D3 having the formula

21. 25-Hydroxycyclovitamin D3 having the formula

22. l.alpha.,25-Dihydroxycyclovitamin D3 having the formula

23. 1.alpha.,25-Dihydroxycyclovitamin D3-1,25-diacetate having the formula

24. Cyclovitamin D2 having the formula

25. l.alpha.-Hydroxycyclovitamin D2 having the formula

26. l.alpha.-Hydroxycyclovitamin D2-1-acetate having the formula

27. Cyclovitamin D3 having the formula

28. 6-Hydroxycyclovitamin D3 having the formula

29. 6-Acetoxycyclovitamin D3 having the formula

30. l.alpha.,6-Dihydroxycyclovitamin D3 having the formula

31. 24(R),25-Dihydroxycyclovitamin D3 having the formula

32. l.alpha.,24(R),25-Trihydroxycyclovitamin D3 having the formula