IL108914A - 3,5-cyclo-19-nor-vitamin d3 derivatives - Google Patents

Description

D3 1>»1?>1-Ί13-19-1 ρ>ί--5,3 JlH Jl 3,5-Cyclo-19-nor-vitamiii D3 derivatives WISCONSIN ALUMNI RESEARCH FOUNDATION C. 92643 This invention relates to novel intermediates useful in the preparation of the biologically active vitamin D compounds, more specifically, the 19-nor-analogs of lcc-hydroxy lated vitamin D compounds described and claimed in Israel Patent Application No. 93455 from which the present Application was divided out.

The present invention provides compounds having the formula: where R is alkyl, hydrogen, hydroxyalkyl, fluoroalkyl and a side chain of the formula: wherein Ri represents hydrogen, hydroxy or O-acyl, R2 and R3 are each selected from alkyl, hydroxyalkyl and fluoroalkyl, or, when taken together represent the group — (CH2)m — where m is an integer having a value of from 2 to 5, R4 is selected from hydrogen, hydroxy, fluorine, O-acyl, alkyl, riydroxyalkyl and fluoroalkyl, R5 is selected from hydrogen, fluorine, alkyl, hydroxyalkyl and fluoroalkyl, or, R4 and R5 taken together represent double-bonded oxygen, R6 and R? are each selected from hydrogen, hydroxy, O-acyl, fluorine and alkyl, or, R6 and R7 taken together form a carbon-carbon double bond, and wherein n is an integer having a value of from 1 to 5 and wherein the carbon at any one of positions 20, 22. or 23 in the side chain may be replaced by an O, S, or N atom, and where Q is alkyl, X is hydrogen or a hydroxy-protecting group, Y is hydrogen, hydroxy or protected hydroxy, Z is hydrogen or hydroxy-methyl, or Y and Z taken together is an oxo group. - la - Background The Ι -hydroxylated metabolites of vitamin D — most importantly la , 25-dihydroxyvitamin D-j and la/ 25-dihydroxyvi tanin D2 — are known as highly potent regulators of calcium homeostasis in animals and humans, and more recently their activity in cellular differentiation has also been established. As a consequence, many structural analogs of these metabolites, such as compounds with different side chain structures, different hydroxylation patterns, or different stereochemis ry, have been prepared and tested. Important examples of such analogs are la -hydroxyvitamin D3, lcs-hydroxyvitamin D->, various side chain fluorinated derivatives of lc., 25-cihydroxyvita;nir. D3, and side chain homologated analogs. Several of these known compounds exhibit highly potent activity in vito or in vitro, and possess advantageous activity profiles and thus are in use, or have been proposed for use, in the treatment of a variety of diseases such as renal osteodystrophy, vitamin D-resistant rickets, os eoporosis, psoriasis, and certain malignancies.

Israel Patent Application describes a class of la-hydroxylated vitamin D 19-nor-analogs , i.e. compounds in which the ring A exocyclic methylene group (carbon 19) typical of all vitamin D system has been removed and replaced by two hydrogen atoms.

Struc urally these analogs are characterized by the general formula I shown below: Q where X1 and X are each selected from the group consisting of hydrogen and acyl, and where the group R represents any of the typical side chains known for vitamin D type compounds. Thus, R may be an alkyl, hydrogen, hydroxyalkyl or fluoroalkyl group, or R may represent the following side chain: wherein R represents hydrogen, hydroxy or O-acyl, R and R^ are each selected from the group consisting of alkyl, hydroxyalkyl and fluoroalkyl, or, when taken together represent the group — (CH2^n — where m is an integer having a value of from 2 to 5, is selected from the group consisting of hydrogen, hydroxy, fluorine, O-acyl, alkyl, hydroxyalkyl and fluoroalkyl, R^ is selected from the group consisting of hydrogen, -3- fluorine, alkyl, hydroxyalkyl and fluoroalkyl, or, 4 and R-> taken together represent double-bonded oxygen, and R^ are each selected from the group consisting of hydrogen, hydroxy, O-acyl, fluorine and alkyl, or, R^ and R^ taken together form a carbon-carbon double bond, and wherein n is an integer having a value of from 1 to 5, and wherein the carbon at any one of positions 20, 22, or 23 in the side chain may be replaced by an 0, S, or N atom.

Specific important examples of side chains are the structures represented by formulas (a), (b), (c), (d) and (e) below, i.e. the side chain as it occurs in 25-hydroxyvitantin D3 (a); vitamin D3 (b); 25-hydroxyvi tamin D2 (c); vitamin D2 (d); and the C-24-epi er of 25-hydroxyvitamin D2 (e).

In this specification and the claims, the term 'alkyl' signifies an alkyl radical of 1 to 5 carbons in all isomeric forms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, etc., and the terms 'hydroxyalkyl' and ' fluoroalkyl ' refer to such an alkyl radical substituted by one or more hydroxy or fluoro groups respectively, and the term 'acyl' means an aliphatic acyl group of 1 to 5 carbons, such as formyl , acetyl, propionyl, etc. or an aromatic acyl group such as benzoyl, nitrobenzoyl or halobenzoyl. The term -4 - 'aryl' signifies a phenyl-, or an alkyl-, nitro- or halo-subs ituted phenyl group.

The preparation of lct-hydroxy-19-nor-vitamin D compounds having the basic structure shown above can be accomplished by a common general method, using known vitamin D compounds as starting materials. Suitable starting materials are, for example, the vitamin D compounds of the general structure II: where R is any of the side chains as defined above.

These vitamin D starting materials are known compounds, or compounds that can be prepared by known methods.

Using the procedure of DeLuca et al. (U.S. Patent 4,195,027), the starting material is converted to the corresponding lo-hydroxy-3 , 5-cyclovitamin D derivative, having the general structure III below, where X represents hydrogen and 0 represents an alkyl, preferably methyl: R So as to preclude undesired reaction of the la-hydroxy group in subsequent steps, the hydroxy group is converted to the corresponding acyl derivative, i.e. the compound III shown above, where X represents an acyl group, using standard acylation procedures, such as treatment with an acyl anhydride or acyl halide in pyridine at room temperature or slightly elevated temperature (30-70°C) . It should be understood also that whereas the process of this invention is illustrated here with acyl protection of hydroxy functions, alternative standard hydroxy-protecting groups can also be used, such as, for example, alkylsilyl or alkoxyalkyl groups. Such protecting groups are well-known in the art- (e.g. trimethylsilyl, triethylsilyl, t.-butyldimethylsilyl, or tetrahydrofuranyl, methoxymeth l) , and their use is considered a routine modification of experimental detail within the scope of the process of this invention.

The derivative as obtained above is then reacted with osmium tetroxide, to produce the 10,19-dihydroxy analog, IV (where X is acyl), which is subjected to diol cleavage using sodium me aperiodate or similar vicinal diol cleavage reagents (e.g. lead tetraacetate) to obtain the 10-oxo-interraediate , having the structure V below (where X is acyl) : v These two consecutive steps can be carried out according to vh< procedures given by Paaren et al. [J. Org. Cheiu. Β^, 3819 · (1983)]. If the side chain unit, R, carries vicinal diols (e.g. 24 , 25-dihydroxy- or 25 , 26-dihydrox , etc.), these, of course, also need to be protected, e.g. via acylation, silylation, or as the isopropylidene derivative prior to the periodate cleavage reactions.

In most cases, the acylation of the la-hydroxy group as mentioned above will simultaneously effect the acylation of side chain hydroxy functions, and these acylation conditions can, of course, be appropriately adjusted (e.g. elevated temperatures, longer reaction times) so as to assure complete protection of side chain vicinal diol groupings.

The next step of the process comprises the reduction of the 10-oxo-group to the corresponding 10-alcohol having the structure VI shown below (where X is acyl and Y represents hydroxy). When X is acyl, this reduction is carried out conveniently in an organic solvent at from about 0°C to about room temperature, using NaBH^ or equivalent hydride reducing agents, selective for the reduction of carbonyl groups without cleaving ester functions. Obviously, when X is a hydrox -protecting group that is stable to reducing agents, any of the other hydride reducing agents (e.g. LiAlH^, or analogous reagents) may be employed also. 1 The 10-hydroxy intermediate is then treated with an alkyl- or arylsulfonylhalide (e.g. mathanesulfonylchloride) in a suitable solvent (e.g. pyridine) to obtain the corresponding 10-0-alkyl-or arylsulfonyl derivative (the compound having the structure shown VI above, where Y is alkyl-SO^O-, or aryl-SO^O-, and this sulfonate intermediate is then directly reduced, with lithiun aluminum hydride, or the analogous known lithium aluminum alkyl hydride reagents in an ether solvent, at a temperature ranging from 0°C to the boiling temperature of the solvent, thereby displacing the sulfonate group and obtaining the 10-deoxy derivative, represented by the structure VI above, where X and Y are both hydrogen. As shown by the above structure, a 1-0-acyl function in the precursor compound V is also cleaved in this reduction step to produce the free lc-hydroxy function, and any 0-acyl protecting group in the side chain would, of course, likewise be reduced to the corresponding free alcohol function, as is well understood in the art. If desired, the hydroxy groups at C-l (or hydroxy groups in the side chain) can be reprotected by acylation or silylation or ether formation to the corresponding acyl, alkylsilyl or alkoxyalkyl derivative, but such protection is not required. Alternative hydroxy-procecting groups, such as alkylsilyl or alkoxyalkyl groups would be retained in this reduction step, but can be removed, as desired, at this or later stages in the process by standard methods known in the art.

The above lo-hydroxy-10-deoxy cyclovitaoin D intermediate is next solvolyzed in the presence of a low-iaolecular weight organic acid, using the conditions of DeLuca et al. (U.S.

Patents A,195,027 and A, 260,549)- When the solvolysis is carried out in acetic acid, for example, there is obtained a mixture of la-hydroxy-19-nor-vitamin D 3-acetate and la-hydroxy-19-nor-vitamin D 1-acecate (compounds VII and VIII» below), and the analogous 1- and 3-acylates are produced, when alternative acids are used for solvolysis.

Direct basic hydrolysis of this mixture under standard conditions then produces the desired la-hydroxy-19-nor-vitamin 1 2 D compounds of structure I above (where X and X are hydrogen). Alternatively, the above mixture of monacetates may also be separated (e.g. by high pressure liquid chromatography) and the resulting 1-acetate and 3-acetate isomers may be subjected separately to hydrolysis to obtain the same final product from each, namely the la-hydroxy-19-nor-vitamin D compounds of structure I. Also the separated monoacetates of structure VII or VIII or the free 1,3-dihydroxy compound can, of course, be reacylated according to standard procedures with any desired acyl group, so as to produce the product of 1 2 structure I above, where X and X represent acyl groups which may be the same or different.

This invencion is more specifically described by che following illuscracive examples. In these examples specific products identified by Roman numerals and letters, i.e. Ia, lb, Ila, lib etc. refer to the specific structures and side chain combinations identified in che preceding description.

Example 1 Preparation of la,25-dihydroxy-19-nor-vicamin (la) (a) la,25-Dihydroxy-3,5-»cyclovicamin 1-acetate, 6-inethyl ether: Using 25-hydroxyvitamin D3 (Ila) as starting material, the known la,25-dihydroxy-3 ,5-cyclovicarain D. derivacive Ilia (X=H) was prepared according to published procedures (DeLuca e al. , U.S. Patent 4, 195,027 and Paaren et al. , J. Org. Chem. 45 , 3252 (1980)). This product was then acetylated under standard conditions to obtain the corresponding 1-acetate derivative Ilia (X-Ac). (b) 10 , 19-Dihydro-la,10, 19 , 25-tetrahydroxy-3 ,5-cyclovitamin 1-acetate, 6-methyl ether (IVa) ; Intermediate Ilia (X=Ac) was created with a slight molar excess of osmium tetroxide in pyridine according to the general procedure described by Paaren t_ al. (J. Org. Chem. 48, 3819 (1983)) to obtain the 10,19-dihydroxylated derivative IVa. Mass spectrum m/z (relative intensity), 506 (M+, 1), 488 (2), 474 (40), 425 (45), 396 (15), 285 (5), 229 (30), 133 (45), 59 (80), 43 (100). ½ . NMR (CDC13) 5 0.52 (3H, s, 18-CH3) , 0.58 (1H, m, 3-H) , 0.93 (3H, d, J=6.1 Hz, 21-CH3), 1.22 (6H, s, 26-CH3 and 27-CIi3 , 2.10 (3H, s, C0CH3), 3.25 (3H, s, 6-0CH3) , 3.63 (2H, m, 19-CH2), 4.60 (1H, d, J=9.2 Hz, δ-Η) , 4.63 (ΙΗ,. dd, 1(J-H) , 4.78 (1H, d, J=9.2 Hz, 7-H). (c) la, 25-Dihydroxy-10-oxo-3,5-cyclo-19-nor-vitarain 1-acetate, 6-methyl ether (Va) ; The 10,19-dihydroxylated intermediate IVa was treated with a solution of sodium mecaperiodate according to the procedure given by Paaren et_ al. (J. Org. Chem. ^8_, 3819, 1983) to produce the 10-oxo-cyclovitamin D derivative (Va, X=Ac). Mass spectrum m/z (relative intensity) 442 (M+-Me0H) (18), 424 (8), 382 (15), 364 (35), 253 (55), 225 (25), 197 (53), 155 (85), 137 (100). ½ NMR (CDC13) δ 0.58 (3H, s, 18-CH3) , 0.93 (3H, d, J=6.6 Hz, 21-CH3), 1.22 (6H, s, 26-CH3 and 27-CH3) , 2.15 (s, 3-0C0CH3) , 3.30 (3H, s, 6-0CH3), A.61 (1H, d, J=9.1 Hz, 6-H) , 4.71 (1H, d, J=9.6 Hz, 7-H), 5.18 (1H, o, Ιβ-H) .

Ic has beeii found also Chat this diol cleavage reaction does not require elevated temperatures, and it is, indeed, generally prefereable to conduct the reaction at approximately room temperature. (d) la-Acetoxy-10,25-dihydroxy-3,5-cyclo-19--nor-vitamin 6-methyl ether (Via, X-Ac, Ύ-0Η) ; The 10-oxo derivative Va (X-Ac) (2.2 mg, 4.6 ttmol) was dissolved in 0.5 ml of ethanol and to this solution 50 yl (5.3 ymol) of a NaBH^ solution (prepared from 20 mg of NaBH^, 4.5 ml water and 0.5 ml of 0.01 N NaOH solution) was added and the mixture stirred at 0°C for ca. 1.5 h, and then kept at 0°C for 16 h. To the mixture ether was added and the organic phase washed with brine, dried over HgSO^, filtered and evaporated. The crude product was purified by column chromatography on a 15 x 1 cm silica gel column and the alcohol Via (X=Ac, Y=0H) was eluted with ethyl acetate hexane mixtures to give 1.4 mg (3 yraol) of product. Mass spectrum m/z (relative intensity) 476 (M ) (1) , 444 (85) , 426 (18), 384 (30), 366 (48), 351 <21) , 255 (35), 237 (48), 199 (100), 139 (51), -59 (58). (e) lQ,25-Dihydroxy-19-nor-vitamin (la, X^X^H : The 10-aicohol (Via, X=Ac, Y=0H) (1.4 mg) was dissolved in 100 yl anhydrous CH2C12 and 10 yl (14 ymol) triethylaminc solution [prepared from 12 mg (16 yl) triethylamine in 100 yl anhydrous CH2C123, followed by 7 yl (5.6 ymol) mesyl chloride solution (9 ng mesyl chloride, 6.1 yl, in 100 yl 'anhydrous CH2C12) added at 0°C. The mixture was stirred at 0°C for 2 h. The solvents were removed with a stream of argon and the residue (comprising compound Via, X=Ac, Y=CH,S0 0-) dissolved in 0.5 ml of - 12 - anhydrous tetrahy rofuran; 5 tng of LiAlH^ was added at 0°C and the mixcure kepc ac 0°C for 16 h. Excess LiAlH^ was decomposed wich wee echer, Che ether phase was washed with water and dried over MgSO^, filtered and evaporated to give he 19-nor product Via (X=Y»H).

This product was dissolved in 0.5 ml of acetic acid and scirred at 55°C for 20 min. The mixcure was cooled, ice water added and extracted with echer. The other phase was washed with cold 10Z sodium bicarbonate solution, brine, dried over MgSO^,, filtered and evaporated to give che expected mixture of 3-acetoxy-la-hydroxy- and la-acecoxy-3-hydroxy isomers, which were separated and purified by HPLC (Zorbax Sil column, 6.4 x 25 cm, 2-propanol in hexane) to give about 70 yg each of compounds Vila and Xllla. UV (in EtOH) λ 242.5 (OD 0.72), 251.5 (OD 0.86), 260 (OD 0.57).

Both 19-nor-l,25-dihydroxyvitamin D3 acetates Vila and Villa were hydrolyzed in the same manner. Each of the monoacecaces was dissolved in 0.5 ml of ether and 0.5 ml 0.1 N 0H in methanol was added. The mixture was stirred under argon atmosphere for 2 h'. More ether was added and the organic phase washed with brine, dried over anhydrous MgSO^, filtered and evaporated. The residue was dissolved in a 1:1 mixture of 2-propanol and hexane and passed through a Sep Pak column and washed with the same solvent. The solvents were evaporated and the residue purified by HPLC (Zorbax Sil, 6.4 x 25 cm, 10% 2-propanol in hexane). The hydrolysis products of Vila and 1 2 Villa were identical and gave 66 yg of la (X «=X =H). Mass spectrum (m/z relative intensity) 404 (M+) (100), 386 (41), 371 (20), 275 (53), 245 (51), 180 (43), 135 (72), 133 (72), 95 (82), 59 (18), exact mass calcd. for C26H 403 404.3290, found - 13 - 404.3272. H MR (CDCL.) 5 0.52 (3H, s, 18-CH3) , 0.92 (3H, d, J=6.9 Hz, 21-CH3), 1.21 (6H, s, 26-CH3 and 27-Cl!.j) , 4.02 (1H, m, 3a-H), 4.06 (1H, m, 1β-Η) , 5.83 (1H, d, J-11.6 Hz, 7-H) , 6.29 (1H, d, J-10.7 Hz, 6-H) . UV (in EtOH) , λ 243 (0D max 0.725), 251.5 (0D 0.S23), 261 (OD 0.598).

Example 2 Preparation of la-hydroxy-19-nor-vicamin (lb) (a) With vitamin (lib) as starting material, and utilizing the conditions of Example la, there is obtained known la-hydroxy-3,5-cyclovitamin l-acctate, 6-methyl ether, compound Illb (X«*Ac) .

Example 3 Preparation of la,25-dihydroxy-19-nor-vitamin (a) Utilizing 25-hydroxyvitamin (He) as starting material and experimental conditions analogous to those of Example la, there is obtained la,25-dihydroxy-3,5-cyclovicanin 1-acetate, 6-methyl ether, compound IIIc (X=Ac) . (b) Subjecting intermediate Hid Example & Preparation of la-hydroxy-19-nor-vitarain D2 (a) With vitamin D∑ (lid) as starting material, and utilizing the conditions of Example la, .there is obtained known la-hydroxy-3,5-cyclovitamin D., 1-acetate, 6-methyl ether, compound Hid (X=Ac) . (b) By subjecting intermediate Hid (X=Ac) , as obtained in Example 4a above to the conditions of Example lb, there is - 15 - obtained 10,19-dihydro-la,10,19-trihydroxy-3,5-cyclovitarain 1-acetate, 6-methyl ether, IVd (X=Ac) . (c) By treatment of intermediate IVb (X~Ac) with sodium metaperiodate according to Example lc above, there is obtained la-hydroxy-10-oxo-3,5-cyclo-19-nor-vitamin 1-acccate, 6-tnethyl ether, Vd (X=Ac) . (d) Upon reduction of the 10-oxo-intcrmediate Vd (X=Ac) under the conditions of Example Id above, there is obtained la-acetoxy-10-hydroxy-3,5-cyclo-19-nor-vitarain 6-raethyl ether, VId (X-Ac, Y=0H) . (e) Upon processing intermediate VId (X=Ac, Y=0H) through the procedure given in Example le above, there is obtained la-hydroxy-19-nor-vitamin D∑ (Id, X^X^H) .

The above description may include matter which is not claimed, but is retained herein for the sake of completeness. - 16 -

Claims (4)

1. Compounds having the formula: where R is alkyl, hydrogen, hydroxyalkyl, fluoroalkyl and a side chain of the formula: wherein R1 represents hydrogen, hydroxy or O-acyl, R2 and R3 are each selected from alkyl, hydroxyalkyl and fluoroalkyl, or, when taken together represent the group ~ (CH^im ~ where m is an integer having a value of from 2 to 5, R4 is selected from hydrogen, hydroxy, fluorine, O-acyl, alkyl, hydroxyalkyl and fluoroalkyl, R5 is selected from hydrogen, fluorine, alkyl, hydroxyalkyl and fluoroalkyl, or, R* and R5 taken together represent double-bonded oxygen, R6 and R7 are each selected from hydrogen, hydroxy, O-acyl, fluorine and alkyl, or, R6 and R? taken together form a carbon-carbon double bond, and wherein n is an integer having a value of from 1 to 5 and wherein the carbon at any one of positions 20, 22. or 23 in the side chain may be replaced by an O, S, or N atom, and where Q is alkyl, X is hydrogen or a hydroxy-protecting group, Y is hydrogen, hydroxy or protected hydroxy, Z is hydrogen or hydroxy-methyl, or Y and Z taken together is an oxo group.

2. Compounds according to Claim 1 having the formula where R represents a side chain as defined in Claim 1, 0 represents an alkyl and X is selected from the group consisting of hydrogen, acyl, alkylsilyl and alkoxyalkyl .

3. Compounds according to Claim 1 having the formula: where R is a side chain as defined in Claim 1, Q represents an alkyl and X is selected from the group consisting of hydrogen, acyl, alkylsilyl and alkoxyalkyl.

4. Compounds according to Claim!Γ having the formula: R ' - 18·- where R is a side chain as defined in Claim 1, Q represents an alkyl, X is selected from the group consisting of hydrogen, acyl, alkylsilyl and alkoxyalkyl, and Y is selected from the group consisting of hydroxy, hydrogen and protected hydroxy where the protecting group is acyl, alkylsilyl or alkoxyalkyl . the Applicants