Vitamin D compounds and method of preparing these compounds

The present invention relates to vitamin D compounds of the general formula ##STR1## wherein: R.sub.1 is a hydrogen atom or a hydroxy group; PA1 R.sub.2 is a (C.sub.1 -C.sub.3)alkyl group, a hydroxy(C.sub.1 -C.sub.3)alkyl group, a (C.sub.1 -C.sub.2)alkoxymethyl group or a (C.sub.2 -C.sub.3)alkenyl or alkynyl group; PA1 n is 1; PA1 R.sub.3 is a branched or non-branched, saturated or unsaturated, substituted or unsubstituted aliphatic (C.sub.3 -C.sub.7)hydrocarbon or oxyhydrocarbon biradical; PA1 R.sub.4 is a branched or straight (C.sub.1 -C.sub.6) alkyl group or a (C.sub.3 -C.sub.6)cycloalkyl group; and PA1 A and B are each individually hydrogen atoms or methyl groups, or PA1 A and B form together a methylene group. The present compounds find use in cosmetic application and in human and veterinary pharmacotherapeutic practice in the treatment of skin and bone diseases, diseases related to cell differentiation/cell proliferation, imbalance in the immune system and inflammatory diseases.

The invention relates to new vitamin D compounds, to a method of preparing 
these compounds and to their use in pharmacology. The invention further 
relates to valuable new intermediates. 
It is generally known, that vitamin D compounds or vitamin D related 
compounds ("vitamin D compounds") have a strong biological activity and 
may be used in all those cases in which problems with the calcium 
metabolism play a part. A few years ago it was found that various active 
vitamin D compounds also have other pharmacotherapeutic activities and may 
be used successfully, for example, for the treatment of certain skin and 
bone diseases, for cosmetic applications and for treating diseases which 
are related to cell differentiation, cell proliferation or imbalance in 
the immune system, including diabetes mellitus, hypertension and 
inflammatory diseases such as rheumatoid arthritis and asthma. In 
addition, these compounds may be used in various veterinary applications, 
and for diagnostic purposes. 
It is therefore of the utmost importance to have the disposal of an arsenal 
of active vitamin D compounds for the above various application fields so 
as to be able to make the best possible choice of a vitamin D compound for 
the application in view. 
Vitamin D compounds which are of interest for the above applications are 
hydroxylated vitamin D compounds, in particular vitamin D compounds 
hydroxylated in the 1.alpha.-, 24- and/or 25-positions. Recent 
developments in the field of active vitamin D compounds are 19-nor-vitamin 
D compound (EP-A-0387077), 25,25-di(cyclo)alkyl vitamin D compounds 
(non-prepublished U.S. patent application 08/070,998) and (C-18)-modified 
vitamin D compounds (EP-A-0521550), preferably also hydroxylated in the 
1.alpha.-position and optionally in the (C-17)-side chain. Other 
modifications of the (C-17)-side chain have been proposed, likewise to 
improve the intended activity and to suppress detrimental side-effects. 
Examples of modifications of the (C-17)-side chain are chain elongations 
(homo compounds), 22-oxa modifications, fluor substitutions, epoxy groups 
(e.g. WO 92/21695), etc. Generally, however, the above (C-17)-side chain 
modified vitamin D compounds are still not completely satisfactory as 
regards their selective activity, i.e. the intended activity without 
detrimental side-effects. 
Further, the accessibility of the (C-17)-side chain modified vitamin D 
compounds is often insufficient or unattractive. In this connection there 
is a need for better accessible (C-17)-side chain modified vitamin D 
compounds. As a matter of fact, both the starting compounds for the 
preparation of such vitamin-D compounds must be easily available or 
accessible, and the multistep preparation process must lead to the 
intended purpose with sufficient selectivity and efficiency. 
It is therefore the objective of the present invention to provide a new 
class of vitamin D compounds, which is well accessible from readily 
available or accessible starting materials. 
According to the present invention this objective can be achieved with a 
new vitamin D compound of the general formula 
##STR2## 
wherein: R.sub.1 is a hydrogen atom or a hydroxy group; 
R.sub.2 is a (C.sub.1 -C.sub.3)alkyl group, a hydroxy(C.sub.1 
-C.sub.3)alkyl group, a (C.sub.1 -C.sub.2)alkoxymethyl group or a (C.sub.2 
-C.sub.3)alkenyl or alkynyl group; 
n is 0 or 1; 
R.sub.3 is a branched or non-branched, saturated or unsaturated aliphatic 
(C.sub.3 -C.sub.7)hydrocarbon or oxahydrocarbon biradical, having at least 
3 atoms in the main chain and being optionally substituted with one or 
more substituents selected from fluoro, hydroxy, epoxy or methoxy; 
R.sub.4 is a branched or straight (C.sub.1 -C.sub.6)alkyl group or a 
(C.sub.3 -C.sub.6)cycloalkyl group; and 
A and B are each individually hydrogen atoms or methyl groups, or 
A and B form together a methylene group. 
The above new (C-17)-(C-20)-modified vitamin D compounds of the invention, 
presented by the general formula I, are valuable substances. The 
biological results indicate that these compounds are promising as 
biologically active substances and may be used in all above-mentioned 
pharmacotherapeutic indications, more in particular for the treatment of 
osteoporosis, renal osteodystrophy, osteomalacia, skin disorders such as 
psoriasis (and other hyperproliferative skin diseases), eczema and 
dermatitis, myopathy, leukaemia, breast and colon cancer, osteosarcomas, 
squamous cell carcinomas, melanoma, certain immological disorders, and 
transplant rejections. For this application, the new compounds of the 
invention may be incorporated, in effective amounts, in pharmaceutical 
compositions, comprising in addition pharmaceutical acceptable carriers 
and auxiliary substances. 
Furthermore, the new vitamin D compounds of the invention may be used for 
wound healing and may be incorporated in cosmetic compositions, such as 
creams, lotions, ointments and the like, in order to preserve, condition 
and/or protect the skin and to improve various skin conditions, such as 
wrinkles, dry skin, skin slackness and insufficient sebum secretion. The 
new vitamin D compounds may also be used for diagnostic purposes. 
Preferred is a vitamin D compound of the general formula 
##STR3## 
wherein: R.sub.4 and n have the above meanings; 
R.sub.2 ' is CH.sub.3, CH.sub.2 CH.sub.3, CH.sub.2 OH or CH.dbd.CH.sub.2 ; 
R.sub.3 ' is a biradical of the formula 
EQU --CH.sub.2 --CH.sub.2 --(CH.sub.2).sub.m --, --CH.sub.2 --(CH.sub.2).sub.m 
--CH(CH.sub.3)-- or --(CH.sub.2).sub.p --O--(CH.sub.2).sub.q --, 
wherein m=0-3; p=0-3 and q=1-3, with the proviso that p+q=.gtoreq.2; and 
A' and B' are hydrogen atoms or form together a methylene group. 
In the above formula II compounds R.sub.4 means preferably methyl, ethyl, 
propyl, isopropyl or cyclopropyl, and R.sub.2 ' is preferably methyl. 
It is a merit of the present invention, that the desired C-20 stereoisomers 
can easily be obtained, as will be explained hereinafter. Therefore the 
present invention also relates to a vitamin D compound as defined 
hereinbefore, wherein the (C-20)substituent, i.e. the substituent R.sub.3 
--C(R.sub.4).sub.2 --OH in formula I, has either the E or the Z 
configuration. 
The invention also relates to a method of preparing a vitamin D compound of 
the above formula I as defined above, by subjecting a hydrindane compound 
of the general formula 
##STR4## 
wherein: R.sub.2, R.sub.3, R.sub.4, and n have the above meanings; and 
R.sub.5 and R.sub.5 ' are protected hydroxy groups; 
to deprotection of substituent R.sub.5 and then to an oxidation to the 
corresponding hydrindane-4-one compound of the general formula 
##STR5## 
which compound of formula V is then converted either (a) with a Wittig 
reagent of the general formula 
##STR6## 
wherein: R.sub.5, A and B have the above meanings; and 
R.sub.5 " is a hydrogen atom or a protected hydroxy group; 
or (b), after enolization and derivatization of the enolic hydroxy group, 
with an enyne compound of the general formula 
##STR7## 
wherein R.sub.5 and R.sub.6 " have the above meanings, followed by partial 
hydrogenation and isomerization, to produce a compound of the general 
formula I, wherein A and B form together a methylene group; followed by 
deprotection. 
Hydroxy groups in the above intermediates or reactants may be protected by 
a reaction with a suitable esterification or etherification agent. A 
suitable esterification agent is an alkylchlorocarbonate having 2 to 5 
carbon atoms, or an aromatic carboxylic acid or saturated aliphatic 
carboxylic acid having 1 to 4 carbon atoms such as benzoic acid, or a 
derivative of such acids suitable for the esterification reaction. In 
order to protect in the form of an ether, in principle any etherification 
agent known for this purpose is suitable: for example, a 
methoxymethylating agent (such as methoxymethylchloride), a 
trialkylsilylimidazole, a trialkylsilylhalide, a trialkyl-silyltriflate 
(-trifluoromethanesulfonate), a diphenylalkylsilylhalide, or a 
diphenylalkylsilyltriflate, or a derivative thereof, the alkyl groups of 
which have 1 to 6 carbon atoms. Particularly suitable for this purpose are 
trimethylsilylchloride, tert.-butyldimethylsilylchloride, 
dimethyl-(1,1,2-trimethylpropyl)-silylchloride, tert.-butyldimethylsilyl 
triflate, or trimethylsilyl-imidazole, because these etherification agents 
readily react with the hydroxy group to be protected to form an ether 
function, which on the one hand is sufficiently stable under the 
conditions of the reaction or reactions in view, but on the other hand can 
easily be removed deprotection! to recover the original hydroxy group; 
tert.-butyldimethylsilylchloride or triflate is to be preferred, because 
the tert.-butyldimethylsilyl group has been found to be excellently 
suitable as a protective group. 
The enolic hydroxy group is preferably derivatized by a reaction with 
N-phenyltriflimide to produce a triflate. 
As indicated above, the desired C-20 stereoisomers are readily accessible 
in a high stereochemical purity. Therefore the present invention relates 
also to the synthesis of a specific (C-20)-stereoisomeric vitamin D 
compound of the general formula 
##STR8## 
wherein the symbols have the meanings given hereinbefore; by reacting a 
compound of the general formula 
##STR9## 
wherein: R.sub.2 and R.sub.3 have the above meanings, 
R.sub.5 is a protected hydroxy group, and 
R.sub.6 is a hydrogen atom or a (C.sub.1 -C.sub.6)alkyl group; 
with an organometallic compound of the general formula 
EQU R.sub.4 M(X).sub.p 
wherein: 
R.sub.4 has the above meaning, 
X is Cl, Br or I, 
M is a metal selected from Li and Mg, and 
p is, dependent on the valence of M, 0 or 1; 
after which the hydrindane compound obtained, after protection of the free 
hydroxy group, has the general formula 
##STR10## 
which compound of formula X is selectively deprotected, and then oxidized 
to the corresponding hydrindane-4-one compound of the general formula 
##STR11## 
which compound of formula XI, if desired after protection of the hydroxy 
group, is then converted either 
(a) with a Wittig reagent of the general formula 
##STR12## 
wherein R.sub.5, R.sub.5 ", A and B have the above meanings; or (b), after 
enolization and derivatization of the enolic hydroxy group, with an enyne 
compound of the general formula 
##STR13## 
wherein R.sub.5 and R.sub.5 " have the above meanings, followed by 
hydrogenation and isomerization, to produce a compound of the general 
formula I, wherein A and B form together a methylene group; followed by 
deprotection. 
Suitable examples of organometallic compounds are compounds of the formula 
EQU R.sub.4 --MgX or R.sub.4 Li 
wherein R.sub.4 has the meaning given above and X is a halogen atom. 
Examples of suitable reagents for the above reaction are: R.sub.4 --MgBr, 
R.sub.4 --MgI, R.sub.4 --MgCl and R.sub.4 --Li, wherein R.sub.4 is defined 
above. 
Alternatively compounds of the general formula VIII as defined above can be 
prepared by reacting a compound of the general formula 
##STR14## 
wherein: R.sub.2, R.sub.3, R.sub.5, R.sub.5 ", A and B have the above 
meanings; with an organometallic compound of the general formula 
EQU R.sub.4 M(X).sub.p 
wherein: 
R.sub.4, M, X and p have the meanings given above; followed by 
deprotection. 
The other (C-20)stereoisomers can also be synthesized, e.g. starting from 
the above-defined hydrindane compound X. So a vitamin D compound of the 
general formula 
##STR15## 
wherein the symbols have the meanings given in above; is prepared by 
subjecting the hydrindane compound of the general formula X, defined 
hereinbefore, to an epoxidation of the C--C double bond, producing a 
compound with the general formula 
##STR16## 
followed by removal of the epoxide-oxygen, producing a hydrindane compound 
of the general formula 
##STR17## 
followed by the successive reaction steps as defined above. 
A vitamin D compound of the general formula 
##STR18## 
wherein the symbols have the meanings given hereinbefore; can readily be 
prepared by subjecting the hydrindane compound of the general formula X, 
defined hereinbefore, successively to an addition of dichlorocarbene to 
the C--C double bond (formula XXI, Z configuration) and to a reduction, 
producing a hydrindane compound of the general formula XV, 
##STR19## 
followed by the successive reaction steps as defined above. 
Finally, a vitamin D compound of the general formula 
##STR20## 
wherein the symbols have the meanings given hereinbefore; is prepared by 
subjecting the hydrindane compound of the general formula XIII, defined 
hereinbefore, successively to an addition of dichlorocarbene to the C--C 
double bond (formula XXI, E configuration) and to a reduction, producing a 
hydrindane compound of the general formula XVII, 
##STR21## 
followed by the successive reaction steps as defined above. 
The starting ester compound of formula IX can conveniently be prepared from 
a readily available substance, viz. vitamin D.sub.2, as follows: 
##STR22## 
Vitamin D.sub.2 is degraded (reaction step a), e.g. by an 
ozonolysis-reduction reaction, to the so-called Inhoffen-Lythgoe diol, 
which, after protection (reaction step b), is oxidized (reaction step c) 
to yield an aldehyde. This aldehyde is subjected to an oxidative 
degradation (reaction step d), after which the ketone obtained is 
subjected successively to a Baeyer-Villiger oxidation and an oxidation of 
the alcohol obtained (reaction step e). Finally the hydrindanone obtained 
is subjected to a stereoselective chain-extending reaction (reaction step 
f), e.g. by a Wittig reaction, to yield the desired stereochemically pure 
compound having the above formula IX, wherein R.sub.2 is methyl and 
R.sub.6 is hydrogen. 
The hydrindane intermediate of the above general formula IV is new. 
Therefore the present invention also relates to this intermediate, which 
can be prepared as described hereinbefore. 
A preferred hydrindane intermediate as defined above can be represented by 
the general formula 
##STR23## 
wherein the symbols have the above meanings. 
(C-20)stereochemically pure vitamin D compounds, i.e. vitamin D compounds 
having a stereochemical purity of at least approx. 90%, can be obtained by 
using substantially pure hydrindane stereoisomers as intermediates. The 
present invention therefore also relates to a hydrindane intermediate of 
the above general formula IV, wherein substituent R.sub.3 
--C(R.sub.4).sub.2 --R.sub.5 ' has either the E or the Z configuration. 
The method of preparing these hydrindane stereoisomers is described above. 
The hydrindane-4-one intermediate of above general formula V is also new. 
Therefore the present invention also relates to this intermediate, which 
can be prepared as described above. 
Another new intermediate is the hydrindane intermediate of the above 
general formula XX. Therefore the present invention also relates to this 
intermediate, which can be prepared as described above. 
To improve the applicability of the new vitamin D compounds of the 
invention for the above-described pharmacotherapeutic indications, the 
compounds are usually processed to pharmaceutical compositions, comprising 
an effective amount of said vitamin D compound as the active ingredient in 
addition to a pharmaceutically acceptable carrier and/or at least one 
pharmaceutically acceptable auxiliary substance. Such a composition may be 
delivered in a dosage unit form for oral, topical (dermal) or parenteral 
administration, comprising approx. 0.1 .mu.g to approx. 0.1 mg active 
ingredient per dosage unit. 
A composition for diagnostic purposes may comprise, in addition to the 
vitamin D compound of the present invention, a compatible, non-toxic 
carrier and/or at least one auxiliary substance. 
A cosmetical composition may comprise, in addition to an effective amount 
(in the range of approx. 0.1 .mu.g to approx. 0.1 mg per dosage unit in a 
dosage unit form) of the vitamin D compound of the present invention, a 
cosmetically acceptable, non-toxic carrier and/or at least one auxiliary 
substance. 
Finally the invention relates to a method for the treatment and prophylaxis 
of a number of disease states including autoimmune diseases (including 
diabetes mellitus), acne, alopecia, skin aging (including photo-aging), 
imbalance in the immune system, inflammatory diseases such as rheumatoid 
arthritis and asthma, as well as diseases related to abnormal cell 
differentiation and/or proliferation, in a warm-blooded living being, 
comprising administering to said being or treating said being with a 
pharmaceutical composition as defined above in a quantity effective for 
the intended purpose. Examples of such diseases are psoriasis and other 
hyperproliferative skin diseases. 
The present invention also relates to the use of the above pharmaceutical 
compositions for the treatment of solid, skin and blood cancers, in 
particular of blood cancers such as leukaemia, of breast cancer, and of 
skin cancers such as melanoma and squamous cell carcinoma. 
The above-defined cosmetical compositions, in particular selected from the 
group consisting of creams, lotions, ointments, liposomes and gels, can be 
used for the treatment and prevention of a number of skin disorders, such 
as inadequate skin firmness or texture, insufficient skin hydration, 
wrinkles and insufficient sebum secretion.

The invention will now be described in greater detail with reference to the 
following specific Examples. 
EXAMPLES 
Example I 
Preparation of compound 8, starting from compound 1. 
Reaction equation: see Reaction Scheme A attached. 
Compound 1 is prepared according to the procedure described by Sestelo, PhD 
thesis, Santiago de Compostela 1994, 138 or by Dauben et al., Tetrahedron 
Lett. 1989, 30, 677. 
(a). Oxygen is purged through a solution of t-BuOK (1.8 g) in dry t-BuOH 
(35 ml) at ambient temperature during 10 minutes. A solution of 1 (1.06 g) 
in dry t-BuOH (20 ml) is added and oxygen is purged through the obtained 
solution during 10 minutes and nitrogen during 15 minutes. Water (25 ml) 
is added. The mixture is extracted with Et.sub.2 O (3.times.50 ml). The 
combined organic phase is dried, filtered and concentrated. The residue is 
purified by flash chromatography (1-2% EtOAc/hexane) to give 818 mg 2. 
(b). To a solution of 2 (110 mg) in CH.sub.2 Cl.sub.2 (3 ml), cooled down 
to 0.degree. C., pure m-chloroperbenzoid acid (130 mg) is added. The 
mixture is stirred at room temperature during 7 days. During these 7 days 
additional m-chloroperbenzoic acid is added (60 mg after 24 hours, 50 mg 
after 78 hours, 30 mg after 98 hours and 55 mg after 120 hours). A 
saturated solution of NaHCO.sub.3 (10 ml) and CH.sub.2 Cl.sub.2 (10 ml) is 
added. The water phase is extracted with CH.sub.2 Cl.sub.2. The combined 
organic phase is dried, filtered and concentrated and the resulting 
residue is purified by flash-chromatography (1% EtOAc/hexane) to give 81 
mg 3. 
(c). A solution of 3 (70 mg) in MeOH (2 ml) and water (0.1 ml) is cooled to 
about 5.degree. C. and NaOH (200 mg) is added. The resulting mixture is 
stirred at ambient temperature during 12 hours. A saturated solution of 
NH.sub.4 Cl is added, and the methanol is removed. The residue is 
extracted with Et.sub.2 O (4.times.15 ml). The combined organic phase is 
dried, filtered and concentrated, yielding a white solid material. The 
product is purified by flash chromatography (5% EtOAc/hexane) to give 56 
mg of 4. 
(d). Pyridinium dichromate (85 mg) is added to a solution of 4 (42 mg) in 
CH.sub.2 Cl.sub.2 (8 ml). The resulting suspension is stirred at room 
temperature during 10 hours and filtered through a small layer of hy-flo. 
The mixture is concentrated and the residue is purified by flash 
chromatography (3% EtOAc/hexane) to give 38 mg of 5. The product is 
identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.15 (1H, m, H-8), 2.42 (1H, m, H-16), 
2.04-1.68 (2H, m, H-16 and H-14), 1.10 (3H, s, C.sub.18 --CH.sub.3), 0.90 
(9H, s, (CH.sub.3).sub.3 CSi), 0.05 (6H, s, (CH.sub.3).sub.2 Si). 
(e). A mixture of the Wittig reagent 4-carboxybutyl triphenyl phosphine 
bromide (9.96 g) and t-BuOK in dry benzene (50 ml) is vigorously stirred 
at 80.degree. C. during 3 hours. To the suspension a solution of the 
ketone 5 (1.1 g) in dry benzene is added and the mixture is stirred at 
80.degree. C. during 36 hours. The reaction is quenched by adding water 
(20 ml). The organic phase is washed with water (100 ml). The combined 
water layers are acidified with a 5% solution of HCl (40 ml) and extracted 
with EtOAc (6.times.15 ml). The organic phases are combined, dried and 
filtered. Concentration affords a residue which is purified by flash 
chromatography (5% EtOH/hexane) to give 1.05 g of 6. 
(f). A solution of MeLi in Et.sub.2 O (1.5M, 4 ml) is added to a solution 
of 6 (1.0 g) in dry THF (10 ml), cooled to 0.degree. C. The mixture is 
stirred at room temperature during 12 hours and water is added. The water 
layer is extracted with EtOAc (3.times.10 ml). The resulting organic phase 
is washed with a saturated NaCl solution (20 ml), dried and concentrated. 
The residue is dried over P.sub.2 O.sub.5 and directly used in the 
following step. 
To a solution of the residue of the last step in dry THF (10 ml) at 
-78.degree. C., a solution of MeLi in Et.sub.2 O (1.5M, 5.6 ml) is added. 
The resulting mixture is stirred during 3 hours at that temperature and 
warmed to room temperature. A saturated solution of sodium chloride (15 
ml) is added. The water phase is extracted with EtOAc (3.times.10 ml) and 
the combined organic phases are dried, filtered and concentrated. 
Purification by flash chromatography (7-10% EtOAc/hexane) yields 836 mg of 
compound 7. 
(g). To a solution of compound 7 (1.4 g) in dry CH.sub.2 Cl.sub.2 (30 ml) 
at 0.degree. C. successively is added i-Pr.sub.2 NEt (1.9 ml), 
dimethylamino pyridine (0.12 g) and methoxymethyl chloride (0.8 ml). The 
resulting mixture is stirred at room temperature during 21 hours. The 
reaction is stopped by adding a 5% HCl solution in water (15 ml). The 
organic phase is washed with water, dried, filtered and concentrated. The 
residue is purified by flash chromatography (4% EtOAc/hexane), yielding 
1.431 g of 8. The product is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.92 (1H, tt, J=7.4 Hz and 2.0 Hz, 
H-20), 4.67 (2H, s, OCOH.sub.2 O), 4.05 (1H, m, H-8), 3.34 (3H, s, 
CH.sub.3 O), 2.39 (1H, m, H-16), 2.16 (4H, m, H-22, H-16 and H-14), 1.18 
(6H, s, C.sub.26,27 --CH.sub.3), 1.08 (3H, s, C.sub.18 --CH.sub.3), 0.87 
(9H, s, (CH.sub.3).sub.3 CSi), -0.01 (6H, 2s, (CH.sub.3).sub.2 Si). 
Example II 
Preparation of compound 10, starting from compound 8. 
Reaction equation: see Reaction Scheme A attached. 
(a). To a solution of 8 (300 mg) in dry CH.sub.2 Cl.sub.2, NaHCO.sub.3 (96 
mg, dried under vacuo at 150.degree. C.) and m-chloroperbenzoic acid (150 
mg) is added in portions. The resulting suspension is shielded from light 
and stirred at room temperature during 10 hours. After addition of another 
portion of m-chloroperbenzoic acid (50 mg), the mixture is stirred for 4 
hours. 15 ml of water is added and the water phase is extracted with 
CH.sub.2 Cl.sub.2 (3.times.10 ml). The combined organic phases are dried, 
filtered and concentrated. The residue is purified by flash chromatography 
(6% EtOAc/hexane), yielding 285 mg of the epoxide 9. 
(b). To a solution of Ph.sub.2 PH (0.45 ml) in dry THF (9 ml), cooled to 
0.degree. C. and isolated from daylight, a solution of n-BuLi in hexane 
(2.45M, 1.0 ml) is added. The intense red coloured solution is stirred at 
room temperature during 4 hours. With the aid of a syringe, a solution of 
9 (460 mg) in dry THF (4 ml) is added, and the resulting mixture is 
stirred during 2 hours. On addition of MeI (0.3 ml) a white suspension 
results, which is stirred during 3 hours. After addition of water (30 ml), 
the water phase is extracted with Et.sub.2 O (3.times.15 ml). The combined 
organic phases are dried, filtered and concentrated. The resulting residue 
is purified by flash chromatography (5% EtOAc/hexane), yielding 416 mg of 
10. The product is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.90 (1H, tt, J=7.1 Hz and 2.5 Hz, 
H-20), 4.69 (2H, s, OCH.sub.2 O), 4.08 (1H, d, J=2.4 Hz, H-8), 2.22 (1H, 
m, H-16), 3.35 (3H, s, CH.sub.3 O), 1.20 (6H, s, C.sub.26,27 --CH.sub.3), 
0.98 (3H, s, C.sub.18 --CH.sub.3), 0.89 (9H, s, (CH.sub.3).sub.3 CSi), 
0.02, 0.01 (6H, 2s, (CH.sub.3).sub.2 Si). 
Example III 
Preparation of compound 12 starting from compound 10. 
Reaction equation: see Reaction Scheme A attached. 
(a). To a solution of 10 (145 mg) in CHCl.sub.3 (2 ml), powdered NaOH (205 
mg) and Bu.sub.4 NHSO.sub.4 (10 mg) are added. The resulting suspension is 
stirred at 55.degree. C. during 1 hour. The mixture is cooled to room 
temperature and diluted with CH.sub.2 Cl.sub.2 (15 ml) and water (20 ml). 
The water phase is extracted with CH.sub.2 Cl.sub.2 (3.times.15 ml). The 
combined organic phase is washed with a saturated solution of NaCl in 
water (20 ml), dried, filtered and concentrated. The resulting residue is 
purified by flash chromatography (hexane--2% EtOAc/hexane), yielding 106 
mg of compound 11. 
(b). To a refluxing solution of 11 (56 mg) in dry THF (1 ml) and dry t-BuOH 
(0.1 ml), sodium is added in portions. The reaction is continued until the 
disappearance of solid particles. The reaction mixture is cooled, and ice 
is added. The mixture is concentrated and water (10 ml) is added followed 
by extraction with EtOAc (3.times.10 ml). The combined organic phase is 
dried, filtered and concentrated. The resulting residue is purified by 
flash chromatography (2% EtOAc/hexane), yielding 40 mg of 12. The product 
is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.71 (2H, s, OC.sub.2 O), 4.04 (1H, m, 
H-8), 3.36 (3H, s, CH.sub.3 O), 2.04-1.94 (1H, m, H-14), 1.22 (6H, S, 
C.sub.26,27 --CH.sub.3), 0.95 (3H, s, C.sub.18 --CH.sub.3), 0.89 (9H, s, 
(CH.sub.3).sub.3 CSi), 0.76 (1H, dd, J=9.0 Hz and 4.1 Hz, H-21), 0.53-0.41 
(1H, m, H-20), -0.14 (1H, dd, J=4.2 Hz and 1.3 Hz, H-21), 0.01 (6H, 2s, 
(CH.sub.3).sub.2 Si). 
Example IV 
Preparation of compound 14, starting from compound 8. 
Reaction equation: see Reaction Scheme A attached. 
(a). To a solution of 8 (90 mg) in CHCl.sub.3 (1.2 ml), powdered NaOH (126 
mg) and Bu.sub.4 NHSO.sub.4 (6 mg) is added. The resulting suspension is 
stirred at 55.degree. C. during 1 hour. The mixture is cooled to room 
temperature and diluted with CH.sub.2 Cl.sub.2 (10 ml) and water (15 ml). 
The water phase is extracted with CH.sub.2 Cl.sub.2 (3.times.10 ml). The 
combined organic phase is washed with a saturated solution of NaCl in 
water (20 ml), dried, filtered and concentrated. The resulting residue is 
purified by flash chromatography (hexane--2% EtOAc/hexane), yielding 88 mg 
of compound 13. 
(b) To a refluxing solution of 13 (230 mg) in EtOH (5 ml), sodium is added 
in portions. The reaction is continued until the disappearance of solid 
particles. The reaction mixture is cooled and ice is added. The mixture is 
concentrated and water (20 ml) is added. Extraction with EtOAc (3.times.20 
ml) yields an organic phase that is dried, filtered and concentrated. The 
resulting residue is purified by flash chromatography (2% EtOAc/hexane), 
yielding 180 mg of 14. The product is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.70 (2H, s, OCH.sub.2 O), 4.03 (1H, m, 
H-8), 3.36 (3H, s, CH.sub.3 O), 2.02-1.92 (1H, m, H-14), 1.21 (6H, s, 
C.sub.26,27 --CH.sub.3), 1.11 (3H, s, C.sub.18 --CH.sub.3), 0.89 (9H, s, 
(CH.sub.3).sub.3 CSi), 0.69-0.64 (1H, m, H-20), 0.33 (1H, dd, J=5.6 Hz and 
4.0 Hz, H-21), 0.17 (1H, dd, J=8.4 Hz and 4.0 Hz, H-21), 0.01 (6H, 2s, 
(CH.sub.3).sub.2 Si). 
Example V 
Preparation of compound 21 starting from compound 8. 
Reaction equation: see Reaction Scheme B attached. 
(a). To compound 8 (320 mg) a solution of tetrabutyl ammonium bromide 
(TBAF) in THF (1.1M, 7.5 ml) is added. The resulting mixture is stirred at 
60.degree. C. during 22 hours. A cold saturated solution of NaHCO, (15 ml) 
and Et.sub.2 O are added. The water phase is extracted with Et.sub.2 O 
(3.times.10 ml). The combined organic phases are dried, filtered and 
concentrated. The obtained residue is purified by flash chromatography 
(15% EtOAc/hexane) to give 233 mg of 15. 
(b). To a solution of 15 (221 mg) in dry CH.sub.2 Cl.sub.2 (9.5 ml) 
pyridinium dichromate (814 mg) is added. The resulting suspension is 
stirred at ambient temperature during 5 hours. The mixture is filtered 
through a small layer of silica gel. The silica gel is washed with 
Et.sub.2 O and the obtained solution is concentrated. The residue is 
purified by flash chromatography (15% EtOAc/hexane) to give 208 mg 16. The 
product is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 5.11 (1H, tt, J=7.4 Hz and 2.0 Hz, 
H-20), 4.71 (2H, s, OCH.sub.2 O), 3.37 (3H, s, CH.sub.3 O), 2.59 (1H, dd, 
J=12.0 Hz and 6.2 Hz, H-14), 2.46 (1H, M, H-16), 2.34-2.24 (2H, m, H-9), 
2.20-1.98 (2H, m, H-22), 1.22 (6H, s, C.sub.26,27 --CH.sub.3), 0.85 (3H, 
s, C.sub.18 --CH.sub.3). 
(c). Lithium diisopropyl amide (LDA) is prepared from dry i-Pr.sub.2 NH 
(0.105 ml) and n-BuLi in hexane (2.46M, 0.28 ml) at -78.degree. C. The 
product is dissolved in dry THF (0.9 ml) and stirred at -78.degree. C. 
during 10 minutes and at 0.degree. C. during 30 minutes. The solution of 
LDA is cooled again to -85.degree. C. and slowly added by means of a 
syringe to a solution of 16 (188 mg) in dry THF (4 ml). The reaction 
mixture is stirred at -85.degree. C. during 1 hour and at 0.degree. C. 
during 30 minutes. N-phenyl triflimide (240 mg, recrystallised from 
hexane) is added and the mixture is stirred at 0.degree. C. during 10 
hours. The residue is purified by flash-chromatography (6-10% 
EtOAc/hexane) to give 175 mg 17. 
(d). To a solution of 17 (130 mg) and the enyne 37 (124 mg) in dry DMF (1.6 
ml), Et.sub.3 N (0.14 ml) and (PPh.sub.3).sub.2 PdCl.sub.2 (7 mg) is 
added. The mixture is heated to 75-80.degree. C. and held at that 
temperature during 2 hours, during which time the color changes from 
yellow to black. The reaction mixture is slowly cooled down to room 
temperature and water is added. The mixture is extracted with Et.sub.2 
O/hexane (1:1, 3.times.10 ml). The combined organic phase is washed with 
water (15 ml), dried, filtered and concentrated. The resulting residue is 
purified by flash chromatography, yielding 138 mg of 18. 
(e). To a solution of 18 (91 mg) in hexane (9 ml), a solution of quinoline 
in hexane (0.4M, 0.19 ml) and Lindlar catalyst (68 mg, dried under vacuo) 
is added. The solution is isolated from light and purged with H.sub.2. The 
mixture is stirred in a hydrogen atmosphere during 1 hour. Filtration and 
concentration yields a pale yellow residue of 95 mg of 19, which is used 
immediately in the following reaction step. 
(f). A solution of 19, the product of the previous step, in dry iso-octane 
(4 ml) is heated to reflux during 4 hours. The mixture is cooled down 
slowly to ambient temperature and concentrated. The product is purified by 
flash chromatography (2% Et.sub.2 O/hexane), yielding 87 mg of 20. 
(g). To a solution of 20 (51 mg) in dry EtOH (6 ml) that is deoxygenated 
with argon, cation exchange resin AG 50W-X4 (1.6 g, washed with EtOH 
(4.times.20 ml), dried under vacuo) is added. The resulting suspension, 
shielded from light, is stirred at ambient temperature during 2 hours. The 
solid phase is filtered from the solution and washed with EtOAc 
(4.times.10 ml). After concentration of the solution a yellow residue is 
obtained, which is purified by flash chromatography (30-50% EtOAc/hexane), 
yielding 22 mg of 21. The product is identified by .sup.1 H-NMR and 
.sup.13 C-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 6.36, 6.04 (2H, AB, d, J=11.1 Hz, H-6 
and H-7), 5.33 (1H, s, H-19E), 5.07 (1H, tt, J=7.0 Hz and 1.7 Hz, H-20), 
5.00 (1H, s, H-19Z), 4.44 (1H, dd, J=7.1 Hz and 4.7 Hz, H-1), 4.23 (1H, m, 
H-3), 2.81 (1H, m, H-14), 2.60 (1H, m, H-4), 1.21 (6H, C.sub.26,27 
--CH.sub.3), 0.75 (3H, s, C.sub.18 --CH.sub.3). 
.sup.1 C-NMR (.delta., CDCl3): 149.5 (C), 147.7 (C), 142.5 (C), 133.3 (C), 
124.9 (CH), 120.7 (CH), 117.4 (CH), 111.9 (CH.sub.2), 71.1 (C), 70.8 (CH), 
66.8 (CH), 56.4 (CH), 47.0 (C), 45.2 (CH.sub.2), 43.6 (CH.sub.2), 42.8 
(CH.sub.2), 37.7 (CH.sub.2), 31.2 (CH.sub.2), 29.2 (CH.sub.3), 28.9 
(CH.sub.2), 28.1 (CH.sub.2), 25.4 (CH.sub.2), 23.6 (CH.sub.2), 23.0 
(CH.sub.2), 22.6 (CH.sub.2), 17.5 (CH.sub.3). 
Example VI 
Preparation of compound 28 starting from compound 10. 
Reaction equation: see Reaction Scheme B attached. 
Compound 28 is prepared from coound 10 via a corresponding reaction 
sequence as described in Example V. The intermediate hydrindane-4-one 23 
is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 5.08 (1H, tt, J=7.1 Hz and 2.3 Hz, 
H-20), 4.69 (2H, s, OCH.sub.2 O), 3.35 (3H, s, CH.sub.3 O), 2.43 (1H, dd, 
J=11.7 Hz and 6.5 Hz, H-14), 2.34-2.19 (3H, m, H-9 and H-16), 1.20 (6H, s, 
C.sub.26,27 --C.sub.3), 0.73 (3H, s, C.sub.18 --CH.sub.3). 
The final product 28 is identified by .sup.1 H-NMR and .sup.13 C-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 6.38, 6.05 (2H, AB, d, J=11.4 Hz, H-6 
and H-7), 5.34 (1H, t, J=1.7 Hz, H-19E), 5.01 (2H, m, H-20 and H-19Z), 
4.47 (1H, m, H-1), 4.24 (1H, m, H-3), 2.87-2.82 (1H, m, H-14), 2.64-2.57 
(1H, m, H-4), 1.21 (6H, C.sub.26,27 --CH.sub.3), 0.63 (3H, s, C.sub.18 
--CH.sub.3). 
.sup.13 C-NMR (.delta., CDCl.sub.3): 151.8 (C), 147.7 (C), 142.8 (C), 133.2 
(C), 124.9 (CH), 117.3 (CH), 116.9 (CH), 111.8 (CH.sub.2), 71.1 (C), 70.8 
(CH), 66.8 (CH), 54.8 (CH), 46.6 (C), 45.2 (CH.sub.2), 43.5 (CH.sub.2), 
42.8 (CH.sub.2), 36.6 (CH.sub.2), 29.2 (CH.sub.3), 28.9 (CH.sub.2), 26.0 
(CH.sub.2), 24.5 (CH.sub.2), 23.4 (CH.sub.2), 22.7 (CH.sub.2), 19.1 
(CH.sub.3). 
Example VII 
Preparation of compound 32 starting from compound 12. 
Reaction equation: see Reaction Scheme C attached. 
Compound 32 is prepared starting from compound 12. Until the intermediate 
hydrindane-4-one 30 the reaction sequence is corresponding with that 
described in Example V (first two reaction steps). The intermediate 
hydrindane-4-one 30 is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.70 (2H, s, OCH.sub.2 O), 3.36 (3H, s, 
CH.sub.3 O), 2.68 (1H, dd, J=11.0 Hz and 7.4 Hz, H-14), 2.33-2.14 (2H, m, 
H-9), 1.21 (6H, s, C.sub.26,27 --CH.sub.3), 0.93 (1H, dd, J=9.2 Hz and 4.4 
Hz, H-21), 0.70 (3H, s, C.sub.18 --CH.sub.3), 0.63-0.52 (1H, m, H-20), 
-0.16 (1H, dd, J=4.9 Hz and 0.5 Hz, H-21). Starting from compound 30 the 
following reactions are carried out to obtain compound 32. 
(a). An amount of 38 (128 mg) is dissolved in THF (4 ml) and cooled down to 
-78.degree. C. A solution of n-BuLi in hexane (1.92M, 0.115 ml) is added 
slowly, during which addition an intense red colour is formed. The mixture 
is stirred for 30 minutes at -85.degree. C., followed by a slow addition 
of a solution of 30 (53 mg) in dry THF (1 ml). The reaction mixture is 
stirred at -70.degree. C. during 90 minutes, at -30.degree. C. during 1 
hour and at ambient temperature during 2 hours. The reaction is quenched 
by addition of a drop of water. After concentration, water is added and 
the resulting mixture is extracted with EtOAc (2.times.15 ml). The 
combined organic phase is washed with a saturated solution of NaCl in 
water (15 ml), dried, filtered and concentrated. The resulting residue is 
purified by flash-chromatography to give 109 mg of 31. 
(b). To a solution of 31 (40 mg) in dry MeOH (6 ml), deoxygenated with 
argon, cation exchange resin AG 50W-X4 (1.7 g, washed with MeOH 
(4.times.20 ml), dried in vacuo) is added. The resulting suspension is 
shielded from light, stirred at ambient temperature during 2 days and 
filtered. The solid material is washed with EtOAc (4.times.10 ml). After 
concentration of the solution a yellow residue is obtained, which is 
purified by flash chromatography (30-50% EtOAc/hexane) to give 19 mg of 
32. The product is identified by .sup.1 H-NMR and .sup.13 C-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 6.36, 6.05 (2H, AB, d, J=11.2 Hz, H-6 
and H-7), 5.30 (1H, H-19E), 4.97 (2H, s, H-20 and H-19Z), 4.37 (1H, dd, 
J=7.0 Hz and 4.6 Hz, H-1), 4.16 (1H, m, H-3), 2.83 (1H, dd, J=12.0 Hz and 
3.6 Hz, H-14), 2.55 (1H, dd, J=13.3 Hz and 3.5 Hz, H-4), 2.30-2.20 (2H, m, 
H-9), 1.17 (6H, C.sub.26,27 --CH.sub.3), 0.59 (3H, s, C.sub.18 
--CH.sub.3), 0.55-0.47 (1H, m, H-20), -0.19 (1H, dd, J=4.6 Hz and 0.8 Hz, 
H-21). 
.sup.13 C-NMR (.delta., CDCl.sub.3): 148.6 (C), 143.6 (C), 134.1 (C), 125.1 
(CH), 117.4 (CH), 111.9 (CH.sub.2), 71.2 (CH), 67.2 (CH), 55.3 (CH), 45.8 
(CH.sub.2), 44.6 (CH.sub.2), 44.3 (C), 43.4 (CH.sub.2), 37.0 (C), 36.3 
(C), 34.6 (CH.sub.2), 32.1 (CH.sub.2), 30.1 (CH), 30.0 (CH.sub.2), 29.5 
(CH.sub.3), 28.7 (CH.sub.2), 25.3 (CH.sub.2), 23.5 (CH.sub.2), 18.0 (C), 
17.9 (CH), 17.3 (CH.sub.3) . 
Example VIII 
Preparation of compound 36 starting from compound 14. 
Reaction equation: see Reaction Scheme C attached. 
Compound 36 is prepared from compound 14 via a corresponding reaction 
sequence as described in Example VII. The intermediate hydrindane-4-one 34 
is identified by .sup.1 H-NMR. 
.sup.1 H-NMR (.delta., CDCl.sub.3): 4.70 (2H, s, OCH.sub.2 O), 3.36 (3H, s, 
CH.sub.3 O), 2.71 (1H, dd, J=11.6 Hz and 7.7 Hz, H-14), 2.31-2.15 (2H, m, 
H-9), 1.21 (6H, s, C.sub.26,27 --CH.sub.3), 0.83 (3H, s, C.sub.18 
--CH.sub.3), 0.84-0.71 (1H, m, H-20), 0.50 (1H, dd, J=5.7 Hz and 4.2 Hz, 
H-21), 0.36 (1H, dd, J=8.6 Hz and 4.2 Hz, H-21). 
The final product 36 is identified by .sup.1 H-NMR and .sup.13 C-NMR. 
1H-NMR (.delta., CDCl.sub.3): 6.36, 6.05 (2H, AB, d, J=11.3 Hz, H-6 and 
H-7), 5.30 (1H, H-19E), 4.97 (2H, dd, J=2.1 Hz and 1.2 Hz, H-20 and 
H-19Z), 4.37 (1H, dd, J=7.2 Hz and 4.5 Hz, H-1), 4.16 (1H, m, H-3), 
2.86-2.79 (1H, m, H-14), 2.55 (1H, dd, J=13.3 Hz and 3.4 Hz, H-4), 
2.30-2.22 (2H, m, H-9), 1.16 (6H, C.sub.26,27 --CH.sub.3), 0.74 (3H, s, 
C.sub.18 --CH.sub.3), 0.77-0.64 (1H, m, H-20), 0.46 (1H, dd, J=5.7 Hz and 
4.1 Hz, H-21), 0.28 (1H, dd, J=8.6 Hz and 4.0 Hz, H-21). 
.sup.13 C-NMR (.delta., CDCl.sub.3): 148.6 (C), 143.3 (C), 134.1 (C), 125.0 
(CH), 117.8 (CH), 111.9 (CH.sub.2), 71.1 (CH), 67.2 (CH), 60.6 (C), 56.5 
(CH), 45.7 (CH.sub.2), 44.8 (C), 44.3 (CH.sub.2), 43.4 (CH.sub.2), 38.1 
(CH.sub.2), 37.0 (C), 36.1 (CH.sub.2), 30.5 (CH.sub.2), 30.1 (CH.sub.2), 
29.4 (CH.sub.3), 25.7 (CH.sub.2), 25.0 (CH.sub.2), 23.7 (CH.sub.2), 23.7 
(CH), 19.1 (CH.sub.2), 16.5 (CH.sub.3). 
Example IX 
Affinity to intracellular vitamin D receptor. 
Vitamin D compounds according to the invention are dissolved in ethanol in 
concentrations ranging from 10.sup.-13 to 10.sup.-7 M. The affinity 
towards the calf thymus intracellular vitamin D receptor (VDR) is 
determined in a biological assay. In this assay, .sup.3 
H-1.alpha.,25-dihydroxycholecalciferol (.sup.3 H-1.alpha.,25-DHCC), which 
is specifically bound to the VDR, is replaced by the tested compounds. The 
tested compound 32 has a high VDR-affinity, comparable to that of 
1.alpha.,25-dihydroxycholecalciferol. A high VDR-affinity is indicative 
for a biologically active substance. The tested compounds 21 and 28 have 
moderate VDR-affinities, whereas tested compound 36 has a weak 
VDR-affinity. 
Example X 
Affinity to vitamin D binding protein. 
Vitamin D binding protein (DBP) is the specific carrier for vitamin D and 
its metabolites in blood. The biological activity of vitamin D compounds 
depends on their binding to DBP, because strong binding to DBP will reduce 
the intracellular access to the VDR. Binding to the DBP may also influence 
the half-life of the vitamin D derivatives in circulation. Weak binders 
are rapidly metabolized, which is a favourable aspect in topical 
application. 
In the assay, DBP is incubated with .sup.3 H-1.alpha.,25-DHCC and 
1.alpha.,25-DHCC or with several vitamin D compounds according to the 
invention. To this purpose, the vitamin compounds are dissolved in ethanol 
in concentrations ranging from 10.sup.-11 to 2.5.times.10.sup.-6 M. The 
percentage bound/unbound .sup.3 H-1.alpha.,25-DHCC is then calculated. DBP 
is purified from total human serum. The results are shown in the appended 
FIG. 1. FIG. 1 shows the binding of vitamin D compounds to human vitamin D 
binding protein. .sup.3 H!1.alpha.,25(OH).sub.2 D.sub.3 =.sup.3 
H-1.alpha.,25-DHCC; in the Figure .cndot.=1.alpha.,25-DHCC (known 
compound); .quadrature.=compound 21; .DELTA.=compound 28; o=compound 32 
and .diamond.=compound 36. 
Tested Compounds 21, 28, 32 and 36 all bind rather weakly to the DBP, 
compared to the known compound 1.alpha.,25-DHCC. 
Example XI 
Cell differentiation. 
Vitamin D compounds according to the invention are dissolved in ethanol in 
concentrations ranging from 10.sup.-12 to 10.sup.-6 M and tested for their 
capacity to induce cell differentiation in a HL-60 assay. In this assay, 
biochemical examination of the human leukemic cell line HL-60 is done, in 
order to establish whether cell differentiation has taken place. 
Differentiation is expressed as the maturation parameter nitroblue 
tetrazolium (NBT) reduction. After culturing with the known 
1.alpha.,25-DHCC or with vitamin D compounds of the invention, the 
percentage of cells containing black formazan deposits is determined. An 
increase in the percentage of NBT reducing cells indicates an increase in 
cell differentiation. 
The vitality and proliferation of the cells in the HL-60 cultures are good 
in all conditions tested. 1.alpha.,25-DHCC (known), compound 21, compound 
28, compound 32 and compound 36 all induce differentiation and maturation 
of the HL-60 cells. The optimum effect is found at concentrations in the 
range of 10.sup.-8 to 10.sup.-7 M. 
The NBT-reduction inducing capacity of compound 36 is about 10.times. 
stronger than that of the known 1.alpha.,25-DHCC. Compound 21 and 32 are 
3-5 times more potent in inducing NBT-reduction than 1.alpha.,25-DHCC 
(FIGS. 2 and 3). Compound 28 is as potent as the known 1.alpha.,25-DHCC. 
The above implies that the tested new vitamin D compounds of the invention 
display a higher than or at least the same cell differentiating activity 
as the known 1.alpha.,25-DHCC. 
FIGS. 2 and 3 (appended) show the differentiating effect of the tested 
vitamin D compounds on human leukemia cells of the HL-60 line. In both 
Figures .cndot.=1.alpha.,25-DHCC; in FIG. 2 .gradient. is compound 21 and 
.quadrature. is compound 28; and .DELTA.=compound 36; in FIG. 3, 
.gradient.=compound 32.