The vitamin D.sub.3 derivative 1.alpha.,25,26-trihydroxycholecalciferol which is useful for regulating the calcium metabolism or calcium transport in the body, cholestene intermediates and a process for their preparation are described.

BACKGROUND OF THE INVENTION 
The present invention relates to a vitamin D.sub.3 derivative, namely 
1.alpha.,25,26-trihydroxycholecalciferol of the formula 
##STR1## 
The invention also relates to pharmaceutical preparations comprising the 
compound of formula I, a process for the preparation of the compound of 
formula I, intermediates, and a process for the preparation of said 
intermediates. 
The compound of formula I is prepared in accordance with the invention by 
thermally isomerizing the compound of the formula 
##STR2## 
This isomerization can be carried out according to the method described in 
Steroids 24 (1974) 463 for the isomerization of 
25,26-dihydroxyprecholecalciferol to 25,26-dihydroxycholecalciferol (e.g., 
in ethanol at reflux temperature). 
The compound of formula II can be prepared by irradiating the compound of 
the formula 
##STR3## 
according to the method described in Steroids 24 (1974) 463 for the 
irradiation of 3.beta.,25,26-trihydroxycholesta-5,7-diene to 
25,26-dihydroxyprecholecalciferol. 
The compound of formula III can be prepared by dekatalizing a compound of 
the formula 
##STR4## 
wherein R.sup.1 and R.sup.2 are lower-alkyl; or R.sup.1 and R.sup.2 taken 
together are lower-alkylene, according to the method described in German 
Offenlegungsschrift No. 27 10 062 for the deketalization of 24,25-ketals. 
DETAILED DESCRIPTION OF THE INVENTION 
As used herein, the term "lower alkyl", alone or in combination, denotes a 
straight- or branched-chain saturated hydrocarbon group preferably 
containing from 1 to 6 carbon atoms, for example, methyl, ethyl, propyl, 
isopropyl, butyl, tert.butyl, pentyl and hexyl. The term "lower alkylene" 
denotes a straight- or branched-chain organic radical derived from an 
unsaturated aliphatic hydrocarbon group preferably containing from 1 to 6 
carbon atoms, for example, ethylene, propylene, butylene and the like. The 
term "lower alkoxy" denotes a straight- or branched-chain lower alkyl 
group attached to the remainder of the molecule by oxygen, for example, 
methoxy, ethoxy, propoxy, isopropoxy and the like. The term "acetoxy" 
denotes the residue from the removal of the hydrogen atom of the hydroxy 
portion of acetic acid. The term "aryl" denotes phenyl or phenyl bearing 
one or more substituents selected from the group consisting of lower alkyl 
and lower alkoxy. 
In the formulas represented herein, the various substituents are 
illustrated as joined to the steroid nucleus by one of the following 
notations: a solid line ( ) indicates that a substituent is in the 
.beta.-orientation (i.e., above the plane of the molecule) and a broken 
line ( ) indicates that a substituent is in the .alpha.-orientation 
(i.e., below the plane of the molecule). A wavy line ( ) indicates the 
.alpha.- or .beta.-orientation. 
The compounds of formula IV can be prepared by reacting a compound of the 
formula 
##STR5## 
wherein R.sup.1 and R.sup.2 are as above; R and R' are etherified or 
esterified hydroxy readily cleavable to hydroxy; and X is phenyl 
optionally substituted by lower-alkyl or nitro, with an alkali metal 
hydride such as lithium hydride in a solvent, preferably a hydrocarbon 
such as toluene, at a temperature up to reflux temperature. 
Ether groups which can be cleaved readily, that is, without affecting other 
positions of the molecule, are, for example, groups of the formula R.sup.X 
O--C(R.sup.Y,R.sup.Z)--O-- in which R.sup.Y is hydrogen or lower-alkyl; 
R.sup.X and R.sup.Z are lower-alkyl; or R.sup.X and R.sup.Z taken together 
are C.sub.3-6 -alkylene. Examples of such groups are 
tetrahydropyran-2-yloxy and methoxymethoxy. Examples of esterified hydroxy 
groups denoted by R and R' are formyloxy and C.sub.2-4 -alkanoyloxy groups 
such as acetoxy. Examples of groups denoted by X are phenyl, p-nitrophenyl 
and p-tolyl, preferably the latter. 
The compounds of formula V can be prepared by reacting a compound of the 
formula 
##STR6## 
with a compound of the formula 
EQU H.sub.2 N--NH--X VII 
wherein X, R, R', R.sup.1 and R.sup.2 are as above, in a solvent such as 
methanol at a temperature up to reflux temperature. 
The compound of formula VI can be prepared by oxidizing a compound of the 
formula 
##STR7## 
wherein R, R', R.sup.1 and R.sup.2 are as above, for example, using 
chromium trioxide in the presence of 3,5-dimethylpyrazole or pyridine in a 
solvent such as methylene chloride. 
The compounds of formula VIII can be prepared by hydrogenating a compound 
of the formula 
##STR8## 
wherein R, R', R.sup.1 and R.sup.2 are as above, for example, using Raney 
nickel under a hydrogen atmosphere in a solvent such as ethanol. 
The compounds of formulas II to VI, VIII and IX also form part of the 
present invention. 
The present invention is also directed to a process for the preparation of 
the compounds of formula IX. 
This process comprises reacting a compound of the formula 
##STR9## 
wherein R and R' are as above, in a Wittig reaction with a compound of the 
formula 
##STR10## 
wherein Ar is aryl; and R.sup.1 and R.sup.2 are as above. 
The reaction can be carried out under conditions which are known for Wittig 
reactions. Examples of solvents which can be used are ethers such as 
tetrahydrofuran, dioxane or diethyl ether or hydrocarbons such as toluene, 
and examples of bases which can be used are butyl lithium, sodium hydride, 
sodium amide or potassium tert.butylate. 
Preferably, the ylide is manufactured at a low temperature, for example, at 
-30.degree. C. to -80.degree. C., especially -60.degree. C., in order to 
exclude the possibility of cleaving the i-steroid grouping. 
The reaction of the ylide with a compound of formula X is preferably also 
carried out at a low temperature, for example, at -20.degree. C. to 
0.degree. C., in order to guarantee the preservation of the 
stereochemistry at C-20. 
The compounds of formula XI can be prepared by reacting a compound of the 
formula 
##STR11## 
wherein R.sup.1 and R.sup.2 are as above, with a triarylphosphine in an 
inert organic solvent while warming. 
Since the compounds of formula XI begin to be unstable at temperatures 
above 100.degree. C., the reaction is conveniently carried out at a 
temperature up to 100.degree. C. in a solvent in which a sufficient 
reaction velocity is achieved at such a temperature. The preferred solvent 
is acetonitrile. 
The compounds of formula XII can be prepared by reacting a compound of the 
formula 
##STR12## 
lower-alkyl or nitro; and R.sup.1 and R.sup.2 are as above, with an alkali 
metal iodide. 
The reaction is conveniently carried out in a solvent such as acetone at a 
temperature of from room temperature up to reflux temperature, preferably 
at the latter. 
The compounds of formula XIII can be prepared by reacting a compound of the 
formula 
##STR13## 
wherein R.sup.1 and R.sup.2 are as above, with a compound of the formula 
EQU R.sup.3 (SO.sub.2).sub.Z XV 
wherein R.sup.3 is as above; and Z is chlorine, bromine or iodine. 
The reaction is conveniently carried out in a solvent such as methylene 
chloride in the presence of a weak base such as pyridine at a temperature 
of 0.degree. C. 
The C-atom in position 25 in the compounds of formulas I to VI, VIII and IX 
and the C-atom in the position 4 in the compounds of formulas XII to XIV 
have the R- or the S-configuration. In addition, the 22,23-double bond in 
a compound of formula IX can have the E- or the Z-configuration. The 
aforementioned compounds can, however, also exist in the form of mixtures 
of the R- and S-forms or of mixtures of the E- and Z-forms. R.sup.1 and 
R.sup.2 preferably are methyl in the compounds of formulas IV to VI, VIII, 
IX and XI to XIV, and R and R' preferably are acetoxy in the compounds of 
formulas V, VI, VIII and IX. 
The compound of formula I has similar properties to other 
biologically-active metabolites of vitamin D.sub.3, for example, 
25,26-dihydroxycholecalciferol, and can therefore, in principle, be 
administered in the same manner and dosage as the said metabolites, for 
example, for regulating the calcium metabolism or calcium transport in the 
body. The compounds of formula I is useful especially for the treatment of 
patients with kidney failure or kidney insufficiency. The R- and S-epimers 
of the compound of formula I lower the serum level of 
1.alpha.,25-dihydroxycholecalciferol. Additionally, both the R- and 
S-epimers promote bone mineralization in vitamin D-deficient animals, but 
only the R-epimer promotes bone mineralization in 
disodium-ethane-1-hydroxy-1,1-diphosphinate-blocked animals. The R- and 
S-epimers are useful for treatment of disease states which are 
characterized by higher-than-normal serum levels of the 
endogenously-produced active vitamin D.sub.3 metabolite 
1.alpha.,25-dihydroxycholecalciferol or in conditions in which there is an 
increased sensitivity to 1.alpha.,25-dihydroxycholecalciferol. 
Specifically included among the disease states for which the compound of 
formula I is indicated are hypercalcemia, sarcoidosis, hypercalciuria, 
nephrolithiasis and nephrocalcinosis. 
The compound of formula I can be used as a medicament; for example, in the 
form of pharmaceutical preparations which contain it in association with a 
pharmaceutical, organic or inorganic inert carrier material which is 
suitable for enteral or parenteral administration such as water, gelatin, 
gum arabic, lactose, starch, magnesium stearate, talc, vegetable oils, 
polyalkyleneglycols and the like. The pharmaceutical preparations can be 
made up in solid form, for example, as tablets, dragees, suppositories or 
capsules, or in a liquid form, for example, as solutions, suspensions or 
emulsions. The pharmaceutical preparations may be sterilized and/or may 
contain adjuvants such as preserving, stabilizing, wetting or emulsifying 
agents, salts for varying the osmotic pressure or buffers. They can also 
contain still other therapeutically-valuable substances.

The following examples further illustrate the invention: 
EXAMPLE 1 
1.alpha.,25(R,S),26-Trihydroxy-22-Dehydrocholesterol-25,26-Acetonide-1,3-Di 
acetate 
2.303 g of 
(R,S)-[2-(2,2,4-trimethyl-1,3-dioxolan-4-yl)-ethyl]-triphenylphosphonium 
iodide were mixed with 10 ml of tetrahydrofuran under argon. 2.5 ml of 
butyl lithium as a 2 molar solution in hexane were added dropwise at 
-78.degree. C., and the mixture was stirred for 1.5 hours. To the 
resulting solution there were added dropwise at -60.degree. C. 1.10 g of a 
solution of (20S)-1.alpha.,3.beta.-diacetoxy-20-formyl-pregn-5-ene in 
tetrahydrofuran. After 30 minutes, the mixture was left to stand at room 
temperature and stirred overnight. Then, water was added, and the mixture 
was extracted with ether. After drying, concentration and chromatography 
on 100 g of silica gel with hexane/ether/ethyl acetate (4:4:1), there were 
obtained 0.69 g (47%) of 
1.alpha.,25(R,S),26-trihydroxy-22-dehydrocholesterol-25,26-acetonide-1,3-d 
iacetate. 
The aforementioned phosphonium iodide can be prepared as follows: 
4.38 g of 2-methylbutane-1,2,4-triol-1,2-acetonide and 5.50 g of tosyl 
chloride were dissolved in 10 ml of methylene chloride. 4 ml of pyridine 
were added dropwise at 0.degree. C., and the mixture was then left to 
stand at 0.degree. C. for 1 hour and at room temperature for 1 hour. After 
the addition of 100 g of ice and then of 100 ml of 1 N sulfuric acid, the 
mixture was extracted with methylene chloride. After drying and 
concentration, there were obtained 6.5 g (97%) of 
4-(2-tosyloxyethyl)-2,2,4-trimethyl-1,3-dioxolane. 
6.5 g of 4-(2-tosyloxyethyl)-2,2,4-trimethyl-1,3-dioxolane were heated at 
reflux temperature for 1 hour with 50 g of sodium iodide and 500 ml of 
acetone, then concentrated, suspended in 100 ml of toluene and filtered. 
The toluene solution was washed with sodium thiosulphate solution, dried 
and concentrated. There were obtained 6.0 g (97%) of 
4-(2-iodoethyl)-2,2,4-trimethyl-1,3-dioxolane. 
6.0 g of 4-(2-iodoethyl)-2,2,4-trimethyl-1,3-dioxolane and 10 g of 
triphenylphosphine were dissolved in 200 ml of acetonitrile and heated at 
reflux temperature for 70 hours. The yellow solution was concentrated, 
mixed with ether, left to stand, then washed with ether and dried in a 
high vacuum. There were obtained 10.6 g (91%) of 
(R,S)-[2-(2,2,4-trimethyl-1,3-dioxolan-4-yl)-ethyl]-triphenylphosphonium 
iodide in the form of hygroscopic crystals of melting point 49.degree. to 
50.degree. C. 
EXAMPLE 2 
1.alpha.,25(R,S),26-Trihydroxy-22-Dehydrocholesterol-25,26-Acetonide-1,3-Di 
acetate 
0.94 g of 
(R,S)-[2,2,4-trimethyl-1,3-dioxolan-4-yl)-ethyl]-triphenylphosphonium 
iodide were dissolved in 10 ml of tetrahydrofuran under argon. 2.5 ml of 
butyl lithium (2 molar in hexane) were added dropwise at -30.degree. C. 
The mixture was stirred for 2 hours. A solution of 0.40 g of 
(20S)-1.alpha.,3.beta.-diacetoxy-20-formyl-pregn-5-ene in 1 ml of 
tetrahydrofuran at the same temperature as before. The mixture was stirred 
at room temperature overnight. After working up in a manner analogous to 
that described in Example 1, there were obtained 321 mg (78%) of 
1.alpha.,25(R,S),26-trihydroxy-22-dehydrocholesterol-25,26-acetonide-1,3-d 
iacetate. 
EXAMPLE 3 
1.alpha.,25(R,S),26-Trihydroxycholesterol-25,26-Acetonide-1,3-Diacetate 
61 mg of 
1.alpha.,25(R,S),26-trihydroxy-22-dehydrocholesterol-25,26-acetonide-1,3-d 
iacetate were dissolved in 10 ml of ethanol and shaked for 8 hours with 
Raney nickel under a hydrogen atmosphere. After filtration and 
concentration, there were obtained 64 mg (100%) of 
1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diacetate; 
[.alpha.].sub.D.sup.20 =-13.6.degree. (c=0.55% in chloroform). 
EXAMPLE 4 
7-Keto-1.alpha.,25(R,S),26-Trihydroxycholesterol-25,26-Acetonide-1,3-Diacet 
ate 
1.4 g of chromium trioxide were suspended in 10 ml of methylene chloride. 
1.4 g of 3,5-dimethylpyrazole were added thereto at -20.degree. C. The 
mixture was then stirred for 15 minutes. Then, a solution of 0.55 g of 
1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diacetate in 
1 ml of methylene chloride was added dropwise. The mixture was stirred at 
-20.degree. C. for 1 hour and at room temperature for 3 hours, then the 
solution was treated with 20 ml of ether, filtered, washed with ether, 
concentrated and purified on silica gel with toluene/ethyl acetate (2:1). 
There were obtained 0.35 g (62%) of 
7-keto-1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diace 
tate. 
EXAMPLE 5 
1.alpha.,25(R,S),26-Trihydroxycholesterol-25,26-Acetonide-1,3-Diacetate-7-T 
osylhydrazone 
0.35 g of 
7-keto-1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diace 
tate and 0.32 g of tosyl hydrazine were dissolved in 10 ml of methanol. The 
mixture was heated at reflux temperature for 5 hours, then concentrated 
and chromatographed on silica gel with toluene/ethyl acetate (2:1). There 
were obtained 0.45 g (100%) of 
1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diacetate-7- 
tosylhydrazone. 
EXAMPLE 6 
1.alpha.,25(R,S),26-Trihydroxy-7-Dehydrocholesterol-25,26-Acetonide 
0.45 g of 
1.alpha.,25(R,S),26-trihydroxycholesterol-25,26-acetonide-1,3-diacetate-7- 
tosylhydrazone were dissolved in 20 ml of toluene and heated at reflux 
temperature for 2 hours with 0.50 g of lithium hydride. 10 ml of methanol 
and 10 g of ice were added at 0.degree. C. The mixture was extracted with 
ethyl acetate, the organic phase was dried with magnesium sulfate and, 
after concentration, chromatographed on silica gel with toluene/ethyl 
acetate 2:1. There were obtained 0.20 g (70%) of 
1.alpha.,25(R,S),26-trihydroxy-7-dehydrocholesterol-25,26-acetonide. 
EXAMPLE 7 
1.alpha.,25(R,S),26-Trihydroxy-7-Dehydrocholesterol 
0.20 g of 
1.alpha.,25(R,S),26,trihydroxy-7-dehydrocholesterol-25,26-acetonide were 
dissolved in 30 ml of methanol and stirred at room temperature for 3 hours 
with 2 g of acid ion-exchanger. Then, the mixture was filtered and 
concentrated to give 0.15 g (82%) of crude product. Crystallization from 
methylene chloride gave 80 mg (44%) of 
1.alpha.,25(R,S),26-trihydroxy-7-dehydrocholesterol of melting point 
124.degree. to 126.degree. C. 
The provitamin obtained was converted according to the method described in 
Steroids 24 (1974) 463 via 
1.alpha.,25(R,S),26-trihydroxyprecholecalciferol into 
1.alpha.,25(R,S),26-trihydroxycholecalciferol; UV in 95% ethanol, 
.lambda..sub.max. 266 nm, .lambda..sub.min. 228 nm; TLC [ethyl 
acetate/methanol (9:1)], Rf=0.32.