GB2158442A - Cyclovitamin D compounds - Google Patents

Abstract

Cyclovitamin D compounds of formula <IMAGE> where Y is H1 hydroxy or O-acyl and Z is alkyl are used as intermediates in the preparation of 1 alpha ,25- dihydroxy Vitamin D2 compounds.

Description

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1 GB 2 158442A 1 .DTD:

SPECIFICATION .DTD:

1,25-dihydroxylated vitamin D2 compounds and intermediates in the preparation thereof This invention relates to the preparation of 1e,25-dihydroxylated compounds of the vitamin D2 5 series, especially 1,25-dihydroxyvitamin D2 and its (24R)-epimer, the corresponding 5,6-trans- isomers, and certain C-25-alkyl and awl analogs and acyl derivatives thereof.

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The importance of the hydroxylated forms of vitamin D as regulators of calcium and phosphate metabolism in animals and humans is now well recognized and, as a consequence, these hydroxyvitamin D derivatives are finding increasing clinical and veterinary use as 10 medicaments for the treatment and cure of disorders of calcium metabolism and associated bone diseases. Vitamin D3 is known to be hydroxylated in vivo to 25hydroxyvitamin D3 and then to 1e,25-dihydroxyvitamin D3, the latter being generally accepted as the active hormonal form of vitamin D3. Similarly, the very potent vitamin D2 metabolite, 1,25- dihydroxyvitamin D2 (1, 25(OH)2D2) is formed from vitamin D2 via 25-hydroxyvitamin D2 (25-OH-D2). Both of these 15 hydroxylated vitamin D2 compounds have been isolated and identified; being derived from vitamin D2, these metabolites are characterized by the (S)- stereochemistry at carbon 24.

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A chemical process for preparing 1x,25-dihydroxylated vitamin D2 compounds having the general structures A and B wherein R1, R2, and R3 are independently hydrogen or acyl, and X is alkyl or aryl has been found. In these structures the asymmetric center at carbon 24 may have the (R) or (S) configuration.

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Specific examples of compounds obtainable by the process include 1,25dihydroxyvitamin D2, the corresponding (24R)-epimer, 1x,25-dihydroxy-24-epivitamin D2, the respective 5,6- 35 trans-isomers, i.e. 5,6-trans-1e,25-dihydroxyvitamin D2, and 5,6-trans-l, 25-dihydroxy-24- epivitamin D2, as well as the C-25-alkyl or aryl homologs of these compounds, e.g. where X is ethyl, propyl, isopropyl or phenyl.

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As used herein the term "acyl" signifies aliphatic acyl (alkanoyl group) of from 1 to 6 carbons, in all possible isomeric forms, e.g. formyl, acetyl, butyryl, isobutyryl or valeryl, or 40 aromatic acyl (aroyl group) such as benzoyl, or methyl, halo, or nitro- substituted benzoyl, or an acyl group derived from a dicarboxylic acid having the general formulae ROOC(CH2),CO-, or ROOCCH2-O-CH2CO-, where n is 0 or an integer from 1 to 4, and R is hydrogen or an alkyl radical, such as oxalyl, malonyl, succinoyl, glutaryl, adipyl or diglycolyl. The term "alkyl'" refers to a hydrocarbon group of 1 to, say, 6 carbons in all isomeric forms, e.g. methyl, ethyl, propyl, 45 isopropyl, butyl or isobutyl. The term "aryl'" refers to an aromatic radical such as phenyl, benzyl, or the isomeric alkyl-substituted phenyl radicals.

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An embodiment of the process of this invention is depicted in Process Scheme I. In the following description, numerals (e.g. 1, 2, 3, etc) refer to the structures so numbered in Process .DTD:

Scheme I. A wavy line to the substituent (methyl) at C-24 indicates that this substituent may 50 have either the R or S configuration.

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A suitable starting material for the process of this invention is the vitamin D-ketal derivative of structure (1) which can be obtained following Process Schemes II and III as described in British Specification No. 2127023 to which reference should be made for further details. It is generally convenient (e.g. when both C-24-epimers are desired) to use compound (1) as a mixture of the 55 24R and S epimers, separation of the individual 24R and S-epimers being accomplished later.

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However, pure 24S, or pure 24R-epimer of (1) are equally suitable, the former providing the (24S)-1,25-dihydroxy product, and the latter the corresponding (24R) product.

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Starting material (I) can be converted to the desired l-hydroxylated form via cyclovitamin D derivatives (see, e.g.U.S, patents 4,195,027 and 4,260,549). Thus, treatment of compound 60 (I) with toluenesulfonyl chloride in the conventional manner yields the corresponding C-3- tosylate (2), which can be solvolyzed in an alcoholic medium to produce the novel 3,5- cyclovitamin D derivative (3). Solvolysis in methanol yields the cyclovitamin (3)where Z = methyl, whereas the use of other alcohols, e.g. ethanol, 2-propanol or butanol, in this reaction provides the analogous compounds (3), where Z is the alkyl group derived from the 65 2 GB 2 158 442A 2 alcohol, e.g. ethyl, isopropyl or butyl. Allylic oxidation of intermediate (3), typically with selenium dioxide and a hydroperoxide, yields the lo-hydroxy-analog (4), acetylation of which provides the 1-acetate (5, R1 = acetyl). If desired, other 1-O-acylates (structure 5, where R1 = acyl, e.g. the formate, propionate, butyrate or benzoate) can be prepared by analogous conventional acylation reactions. Compound (5) can then be subjected to acid-catalyzed 5 solvolysis. When this solvolysis is conducted in a solvent medium containing water, there is generally obtained the 5,6-cis-vitamin D intermediate (6, R1 = acyl, R2 = H) and the correspond- ing 5,6-trans-compound (7, R1 = acyl, R2 = H) in a ratio of about 3-4:1. These 5,6-cis and 5,6- trans-isomers can be separated at this stage, e.g. by high pressure liquid chromatography. If desired, the C-l-O-acyl group may be removed by base hydrolysis to obtain compounds (6) and 10 (7) where R and R2 = H. Also if desired, these 1-O- monoacylates may be further acylated at the C-3-hydroxy groups, using conventional acylation conditions, to obtain the corresponding 1,3-diO- acylates of structure (6) or (7) where R and R2, which may be the same or different, represent acyl groups. Alternatively, the hydroxy cyclovitamin (4) can be subjected to acid-catalyzed solvolysis in a medium containing a low-molecular weight organic acid to obtain the 5,6-cis and 15 trans compounds (6) and (7) where R = H and R2 = acyl, where the acyl group is derived from the acid used in the solvolysis reaction.

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The next step of the process comprises the removal of the ketal protecting group to produce the corresponding 25-ketone. This step is a critical one, since the ketal to ketone conversion must be accomplished without concomitant isomerization of the 22(23)- double bond to the 20 conjugated 23(24)-position, which can occur under the acidic conditions required for ketal hydrolysis. Furthermore, conditions must be chosen so as to avoid elimination of the sensitive allylic C-l-oxygen function. The conversion can be accomplished successfully by careful hydrolysis at moderate temperatures using acid catalysis. In general from room temperature to the boiling point of the solvent, especially from 50 to 100 F (10 to 38 C) may be used. 25 Suitable acid catalysts include organic acids such as a haloacetic acid, formic acid or a low molecular weight organic sulfonic acid including p-toluene sulfonic acid which is especially preferred. Thus, treatment of the 5,6-cis-compound (6) in aqueous alcohol with p-toluene- sulfonic acid gives the corresponding ketone (8). To avoid undesired elimination of the C-1- oxygen function during this reaction, it is advantageous that the C-l- hydroxy group in 30 compound (6) be protected (e.g. as R1 = acyl, R2 = hydrogen or acyl).

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Subsequent reaction of ketone (8) with a methyI-Grignard reagent then provides the desired 1ol,25-dihydroxyvitamin D2 compound (9). If the starting material, compound (1), is a mixture of the two C-24-epimers, then compound (9) will be obtained as a mixture of the 24S and R- epimers (9a and 9b, respectively). Separation of this epimer mixture can be achieved by 35 chromatographic methods, to obtain 1e,25-dihydroxyvitamin D2 (9a, 24S- stereochemistry) and its 24R-epimer, 1,25-dihydroxy-24-epivitamin D2, of structure 9b, both in pure form. Such separation of epimers is, of course, not necessary if the compounds are intended to be used as a mixture.

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The 5,6-trans-25-ketal-intermediate of structure (7) can be subjected to ketal hydrolysis in an 40 analogous manner, to give the 5,6-trans ketone intermediate (10), which via a Grignard reaction with methyl magnesium bromide or analogous reagent, as with the cis intermediate, gives the 5,6trans-1 e,25-dihydroxyvitamin D2 compounds (11), as the 24S or 24R-epimer, or as a mixture of both epimers depending on the nature of the starting material (1). Again the epimers can be separated by chromatography, to obtain 5,6-trans-1c,25- dihydroxyvitamin D2 ( 1 la) and 45 its 24R-epimer, 5,6-trans-1,25-dihydroxy-24-epivitamin D2 (1 l b).

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The novel side chain ketones (8) and (10) are most useful and versatile intermediates in that they can be used to prepare a variety of 1e,25-dihydroxyvitamin D2-side chain analogs.

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Specifically, they can serve for the preparation of 5,6-cis- or 5,6-trans1e,25-dihydroxyvitamin D2 analogs having the general side chain formula shown below. 50 wherein X is an alkyl or aryl group. For example, treatment of ketone (8) with ethyl magnesium bromide gives the corresponding hydroxyvitamin D2 analog having this side chain wherein X is ethyl. Likewise, treatment of (8) with isopropyl magnesium bromide or phenyl magnesium bromide gives side chain analogs where X is isopropyl or phenyl, respectively. Analogous treatment of the 5,6-trans-25-ketone intermediate of structure (10) with alkyl or aryI-Grignard 60 reagents gives the 5,6-trans-vitamin D2 analog having the side chain above where X is the alkyl or aryl radical introduced by the Grignard reagent employed.

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It is also evident that the reaction of the keto-intermediates (8) or (10) with an isotopically- labeled Grignard reagent (e.g. C3H3MgBr, 4CH3MgBr, C2H3MgBr, etc.) provides a convenient means for preparing 1,25-dihydroxyvitamin D2 or its trans isomer, and the corresponding C-2465 3 GB2 158442A 3 epimers, in isotopically-labeled form, i.e. as with the side chain shown above, wherein X is C3H3, 140H3, 02H3, 136H3, or any other isotopically-labeled alkyl or aryl group.

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The above alkyl or aryl homologuesof the 5,6-cis or trans,1,25-dihydroxyvitamin D2 are useful substitutes for the parent compounds where a greater degree of lipophilicity is desired, whereas the isotopically labeled compounds find use as reagents in analytical applications. 5 Further, although for therapeutic applications the free hydroxy compounds of structures A and B above where R1, R2 and a3 = H are generally used, for some applications the corresponding hydroxy-protected derivatives may be useful or preferred. Such hydroxy- protected derivatives include the acylated compounds of general formuae A and B, wherein one or more of R1, R2 and R3 represents an acyl group. 10 Such acyl derivatives are conveniently prepared from the free hydroxy compounds by conventional acylation procedures, e.g. treatment with an acyl halide, or acid anhydride in a suitable solvent such as pyridine, or an alkyl-pyridine. By appropriate selection of reaction time, acylating agent, temperature and solvent, as is well-known in the art, partially or fully acylated derivatives can be obtained. For example, treatment of 1e,25dihydroxyvitamin D2 (9a) in 15 pyridine solvent with acetic anhydride at room temperature gives the 1,3- diacetate, while the same reaction conducted at elevated temperature yields the corresponding 1,3,25-triacetate.

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The 1,3-diacetate can be further acylated at C-25 with a different acyl group; thus treatment with benzoyl chloride or succinic anhydride gives the 1,3-diacetyl-25- benzoyl-, or 1,3-diacetyl- 25-succinoyl- derivative, respectively. A 1,3,25-triacyl derivative can be selectively hydrolyzed in 20 mild base to provide the 1,3-dihydroxy-25-O-acyl compound, the free hydroxy groups of which can be reacylated, if desired, with different acyl groups. Likewise, a 1, 3-diacyl derivative can be subjected to partial acyl hydrolysis to obtain the 1-O-acyl and the 3-O- acyl compounds, which in turn can be reacylated with different acyl groups. Like treatment of any of the other hydroxyvitamin D2 products (e.g. 9b, 11 a/b, or their corresponding 25- alkyl or aryl analogs) 25 provides the corresponding acyl derivatives.

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Like the known vitamin D2 metabolite, 1,25-dihydroxyvitamin D2 (9a), the novel compounds of this invention especially the products of structure 9b-24R and 1 la- 24S and 1 lb24R, or their acylated derivatives, exhibit pronounced vitamin D-like activity, and thus represent desirable substitutes for known vitamin D2 or D3 metabolites in many therapeutic or veterinary applica- 30 tions. The compounds may be used for correcting or improving a variety of calcium and phosphate imbalance conditions resulting from a variety of diseases, such as vitamin D-resistant rickets, osteomalacia, hypoparathyroidism, osteodystrophy, pseudohypoparathyroidism, osteopo- rosis, Paget's disease, and similar bone and mineral-related disease states known to the medical practice. The compounds can also be used for the treatment of mineral imbalance conditions in 35 animals, for example, the milk fever condition, poultry leg weakness, or for improving egg shell quality of fowl. Their use in the treatment of osteoporosis is particularly noteworthy.

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It is well known that females at the time of menopause suffer a marked loss of bone mass giving rise to spontaneous crush fractures of the vertebrae and fractures of the long bones. This disease is generally known as postmenopausal osteoporosis and presents a major medical 40 problem. The disease which is often accompanied by bone pain and decreased physical activity, is diagnosed by one or two vertebral crush fractures with X-ray evidence of diminished bone mass. It is known that this disease is accompanied by diminished ability to absorb calcium, decreased levels of sex hormones, especially estrogen and androgen, and a negative calcium balance. 45 Methods for treating the disease have varied considerably but to date no really satisfactory treatment is yet known. For example, calcium supplementation by itself has not been successful in preventing or curing the disease and the injection of sex hormones, especially estrogen, which has been reported to be effective in preventing the rapid loss of bone mass experienced in postmenopausal women, has been complicated by the fear of its possible carcinogenicity. Other 50 treatments, for which variable results have again been reported, have included a combination of vitamin D in large doses, calcium and fluoride. The primary problem with this approach is that fluoride induces structurally unsound bone, called woven bone, and in addition, produces a number of side effects such as increased incidence of fractures and gastrointestinal reaction to the large amounts of fluoride administered. 55 Similar symptoms characterize senile osteoporosis and steroid-induced osteoporosis, the latter being a recognized result of long term steroid (corticosteroid) therapy for certain disease states.

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While various metabolites of vitamin D3 increase calcium absorption and retention within the body of mammals displaying evidence of or having a physiological tendency toward loss of bone mass they are also characterized by the complementary vitamin D-like characteristic of 60 mobilizing the calcium in bone in response to physiological needs. It has now been found that the epi compounds of this invention, especially 24-epi-1e,25- dihydroxyvitamin D2 (24-epi-1,25- (OH)2D2), are eminently suitable for the prevention or treatment of physiological disorders in mammals which are characterized by the loss of bone mass because although they express some of the recognized vitamin D-like characteristics affecting calcium metabolism, such as, increasing 65 4 GB 2 158 442A 4 intestinal calcium transport, and effecting bone mineralization, they do not increase serum calcium levels, even at higher dosages. This observed characteristic evinces that the compounds upon administration, do not moblize bone. This fact, along with the ability of the compounds upon administration to mineralize bone, indicates that they are ideal compounds for the prevention or treatment of prevalent calcium disorders which are evidenced by loss of bone 5 mass, for example postmenopausal osteoporosis, senile osteoporosis and steroid-induced osteo- porosis. It will be evident that the compounds will find ready application for the prevention or treatment of other disease states in which the loss of bone mass is an indication such as in the treatment of patients undergoing renal dialysis where loss of bone mass as a consequence of the dialysis is encountered. 10 The unique characteristics of 24-epi-l,25-(OH)2D2 offer the rare opportunity to control mineralization of bone through combination with other of the known vitamin D derivatives which function upon administration to mobilize bone. For example, it is believed that in certain circumstances, such as in the healing of bone fractures, bone must first be mobilized before new bone can be laid down. In such situations treatment with vitamin D or a vitamin D derivative 15 which will induce bone mobilization, e.g. lo-hydroxyvitamin D3 or-D2, 1, 25-dihydroxyvitamin D3 or-D2,25-hydroxyvitamin D3 or-D2, 24,24-difluoro-25-hydroxyvitamin D3, 24,24-difluoro-1x- 25-dihydroxyvitamin D3, 24-fluoro-25-hydroxyvitamin D3 24-fluoro-1,25- dihydroxyvitamin D3, 10,25-dihydroxy-2/-fluorovitamin D3, 26,26,26,27,27,27-hexafluoro-1e,25- dihydroxyvitamin D3, 26,26,26,27,27,27-hexafluoro-25-hydroxyvitamin D3, in combination with 24-epi-(OH)2D2), 20 or other 24-epi compound of this invention, will, by adjustment of the proportions of the 24-epi compound and the bone-mobilizing vitamin D compound in the treatment regimen permit the rate of mineralization of bone to be adjusted to achieve the desired medical and physiological ends.

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The compounds of this invention, or combinations thereof with other vitamin D derivatives or 25 other therapeutic agents, specifically 1 e,25-dihydroxy vitamin D2 and 1e, 25-dihydroxy-24-epi- vitamin D2 (9a and 9b) or of the corresponding 5,6-trans-compounds (1 la and 11 b), can be readily administered as sterile parenteral solutions by injection or intravenously or by alimentary canal in the form of oral dosages, or by suppository.

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Dosage forms of the compounds can be prepared by combining them with nontoxic 30 pharmaceutically acceptable carriers as is well known in the art. Such carriers may be either solid or liquid such as corn starch, lactose, sucrose, peanut oil, olive oil, sesame oil and propylene glycol. If a solid carrier is used the dosage form of the compounds may be pills, tablets, capsules, powders, troches or lozenges, for example. If a liquid carrier is used, soft gelatin capsules, or syrup or liquid suspensions, emulsions or solutions in innocuous solvents 35 and oils may be the dosage form. The dosage forms may also contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents or solution promoters. They may also contain other therapeutically valuable substances such as other vitamins, salts, sugars, proteins or hormones.

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Advantageously, the compounds of this invention are administered in dosage amounts of O. 1 40 or 0.5 to 100 #g per day, it being understood, of course, that the specific dosage administered in any given case will be adjusted in accordance with the specific compound administered, the disease to be treated, the condition of the subject and other relevant medical facts that may modify the activity of the drug or the response of the subject, as is well-known by those skilled in the art. 45 In relation to osteoporosis doses of from one-tenth microgram to one microgram per day of 24-epi-1, 25-(OH)2D2 per se are generally effective. Although the actual amount of the 24-epi- compound used is not critical, in all cases sufficient of the compound should be used to induce bone mineralization. Amounts in excess of about one microgram per day of the 24-epi- compound or the combination of that compound with bone mobilization- inducing vitamin D 50 derivatives, are generally unnecessary to achieve the desired results and may not be economi- cally sound practice. In practice the higher doses are used where therapeutic treatment of a disease state is the desired end while the lower doses are generally used for prophylactic purposes.

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The following Examples further illustrate the present invention. 55 Example 1 lo-hydroxy-3,5-cyclovitamin D (4, Z = methyl).

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A solution of compound (1) (50 mg) (as a mixture of the 24R and S epimers) in dry pyridine (300 ul) is treated with 50 mg of p-toluenesulfonyl chloride at 4 C for 3Oh. 60 obtained the corresponding 5,6-trans-hydroxyvitamin D2 products, having the formula shown below GB2 158442A 5 wherein X is, respectively (a) ethyl (b) propyl (c) isopropyl (d) butyl (e) phenyl Example 8 .DTD:

Weanling male rates were placed on the vitamin D deficient diet described by Suda et al., Journal of Nutrition 100, 1049-1052 (1970), modifed to contain.02% calcium and.3% 20 phosphorus. After two weeks on this diet, the animals were given the indicated level of vitamin D compound, either 1,25-dihydroxyvitamin D2, or 24-epi-1, 25- dihydroxyvitamin D2 daily by subcutaneous injection in 0.1 ml of 5% ethanol in propanediol. Twelve hours after the last dose, the animals were killed and blood calcium taken and intestinal calcium transport measured. The results, shown in Table 1 and Fig. 1, represent the blood calcium measure- 25 ments, and the results in Table 2 and Fig. 2 illustrate the intestinal calcium transport measurements performed by the method of Martin and DeLuca, American Journal of Physiology 216, 1351-1359 (1969).

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Table I .DTD:

Dosage Serum Ca (mgll00ml)' 7p tool/day 3.6 20p " 4.2 70p " 4.4 325p " 5.2 650p " 7.9 Compound I, 25- (OH) 2 24-epi-I, 25- (OH) 2D2 7p mol/day 3.5 20p " 3.6 70p " 3.5 325p " 3.6 650p " 3.7 6 GB 2 158 442A 6 1,25- (OH) 2D2 Table .DTD:

Dosage Intestinal calciumtransport {ca serosal/ ca muoosal) 6p tool/day 5.0 13p " 5.2 20p " 5,3 30p " 5.9 ll0p " 6.2 I0 24-epi-I, 25- (OH) 2D2 6p tool/day 3,0 13p " 3.4 20p " 3.'6 30p " 5.0 100p " 4.9 Example 9 .DTD:

Weanling male rats were placed on a high calcium (1.2% calcium) and low phosphorus (. 1% phosphorus) diet described by Suda et al (supra). The rats were fed this diet for a period of three weeks, at which time they were given the indicated doses of the compounds shown in Table 3 in 0.1 ml of 5% ethanol in propanediol subcutaneously. These doses were continued daily for a period of seven days, at which time the animals were killed and serum inorganic phosphorus determined. Results are shown in Table 3 and Fig. 3.

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Bone ash was determined by removing the femurs from rats. The femurs were dissected free of adhering connective tissue, extracted for 24 hours in absolute ethanol, and 24 hours in diethyl ether, using a Soxhlet extractor. The bones are ashed at 600 F for 24 hours. The ash weight was determined by weighing to constant weight. Results are shown in Table 4 and Fig. 4.

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7 GB 2 158 442A 7 Compound I, 25- (OH) 2D2 24-epi-1,25- (OH) 2D2 Ccmx3und 1,25- (OH) 2D2 24-epi-I, 25- (OH) 2D2 Table 3 .DTD:

Serum Inorganic Phos- Dosage pborous (m/100 ml) 30p mI/day 3.4 70p " 3.3 140p " 4.

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325p " 5.5 650p " 5.3 30p m31/day 2.3 f 70p " 2.2 325p " 2.5 650p " 2.7 Table 4 .DTD:

Dosage Total bone ash (m) 65p tool/day 45 350p " 50 750p " 51 65pmol/day 36 350p " 43 750p " 48 I0 The results of the two studies shown in Examples 8 and 9, illustrate that 24-epi-1,25-(OH)2D2 40 is approximately equal in potency to lo,25-dihydroxyvitamin D3 (1,25- (OH)2D3 in causing the mineralization of bone and in stimulating intestinal calcium transport. In short, there is no significant difference between the two groups in Table 2 (Fig. 2) and Table 4 (Fig. 4). On the other hand, the elevation of serum inorganic phosphorus which results from mobilization of bone in the case of the low phosphorus diet is very markedly affected by 1,25-(OH)2D2, but 45 hardly stimulated by 24-epi-1,25(OH)2D2. Similarly, in the mobilization of calcium from bone, even at the extremely high dose level of 750 pmoles/day, the 24-epi compound had no effect, while the mobilization effect is evident at much lower doses of 1,25dihydroxyvitamin D2. Since the rise in serum calcium of rats on a low calcium diet measures the ability to mobilize bone, and since the elevation of blood phosphorus of animals on a low phosphorus diet also measures 50 bone mobilization, these results show that 24-epi-1,25-(OH)2D2 provides an unexpected pro- perty, namely that it is almost of minimal effectiveness in mobilizing bone calcium, while being fully able to stimulate intestinal calcium transport and the mineralization of new bone, properties which make this compound highly suitable for the treatment of disease stages that evince bone loss. 55 The mixture is poured over ice/salt. NaHC03 with stirring and the product is extracted with benzene. The combined organic phases are washed with aqueous CuS04 and water, dried over MgS04 and evaporated.

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The crude 3-tosyl derivative (2) is directly solvolyzed in anhydrous methanol (10 ml) and NaHC03 (150 mg) by heating at 55 C for 8.5 h with stirring. The reaction mixture is then 60 cooled to room temperature and concentrated to2 ml under vacuo. Benzene (80 ml) is then added and organic layer is washed with water, dried and evaporated. The resulting cyclovitamin (3, Z = methyl) can be used in the subsequent oxidation without further purification.

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The crude product (3) in CH2CI2 (4.5 ml) is added to an ice-cooled solution at SeO2 (5.05 rag) and t-BuOOH (16.5 ul) in CH2CI2 (8 ml) containing anhydrous pyridine (50/d). After being 65 8 GB2 158442A 8 stirred for 15 min at O C, the reaction mixture is allowed to warm to room temperature. After an additional 30 rain, the mixture is transferred to a separatory funnel and shaken with 10% NaOH (30 ml). Ether (150 ml) is added and the separated organic phase is washed with 10% NaOH, water, dried and evaporated. The oily residue is purified on silica gel thin layer plates (20 x 20 cm plates, AcOEt/hexane 4:6) to yield 20 mg of l(z-hydroxy derivative (4, Z = methyl): mass 5 spectrum, ree: 470 (M+, 5), 438 (20), 87 (100); NMR (CDCI3) 8 0.53 (3H, s, 18-H3), 0.63 (1H, m, 3-H), 4.19 (1H, d, J =9.5 Hz, 6-H), 4.2 (1H, m, l-H), 4.95 (1H, d, J =9.5 Hz, 7-H), 5.17 and 5.25 (2H, each m, 19-H2), 5.35 (2H, m, 22-H and 23-H).

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Example 2 10 .DTD:

Acetylation of compound (4).

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A solution of cyclovitamin (4, Z = methyl) (18 mg) in pyridine (1 ml) and acetic anhydride (0.33 ml) is heated at 55 C for 2 h. The mixture is poured into ice- cooled sat. NaHCO3 and extracted with benzene and ether. The combined organic extracts are washed with water, saturated CuS04 and aqueous NaHC03 solutions, dried and evaporated to give 1-acetoxy 15 derivative (5, Z = methyl, acyl = acetyl) (19 mg): mass spectrum, ree: 512 (M +, 5), 420 (5), 87 (100); NMR (CDCI3)( 0.53 (3H, s, 18-H3), 4.18 (1H, d, J=9.5 Hz, 6-H), 4.97 (2H, m, 7- H and 19-H), 5.24 (2H, m, 1-H and 19-H), 5.35 (2H, m, 22-H and 23-H).

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Example 3 20 .DTD:

Solvolysis of le-acetoxy-3,5-cyclovitamin (5) (R1 = acetyl).

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A solution of cyclovitamin (5) (4.5 mg) in 3:1 mixture of dioxane/H20 (1. 5 ml) is heated at 55 C. p-Toluenesulfonic acid (1 mg in 20 #1 of H20) is then added and heating is continued for rain. The mixture is poured into saturated NaHCOJice, and extracted with benzene and ether. The organic phases are washed with NaHCO3 and water and dried over MgS04. 25 Evaporation of solvents gives a residue containing, compounds (6) (where R1 = acetyl and R2 = H) and (7) (where R1 = acetyl and R2 = H) which are separated by chromatography on HPLC (6.2 mm X 25 cm Zorbax-Sil) using 2% of 2-propanol in hexane as an eluent. If necessary, the products are further purified by rechromatography.

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Example 4 .DTD:

Ketal hydrolysis in compound (6) to obtain ketone (8).

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(1.5 ml), p- toluenesulfonic acid (0.34 mg in 45/L of H20) is added and the mixture is heated under reflux for 30 min. The reaction mixture is poured into diluted NaHCO3, and extracted with benzene and ether. The combined organic extracts are washed with water, dried over MgS04 and evaporated. High-pressure liquid chromatography of the crude mixture (4% 2-propanol/hexane, 6.2 mm X 25 cm Zorbax-Sil) affords some unreacted ketal (6) (0.12 mg, collected at 48 ml) and desired ketone (8, R1 = acetyl, R2 = H) (0.36 mg, collected at 52 ml), characterized by the following data: mass spectrum, m/e: 454 (M, 9), 394 (17), 376 (10), 134 (23), 43 (100); NMR (CDCI3) 0.53 (3H, s, 18-H3), 1.03 (3H, d, J = 6.5 Hz, 21-H3), 1.13 (3H, d, J = 7.0 Hz, 28-H3), 2.03 (3H, s, CH3CO0), 2.12 (3H, s, CH3CO), 4.19 (1 H, m, 3-H), 5.03 (1 H, m, 19-H), 5.33 (3H, broad m, 19- H, 22-H and 23-H), 5.49 (1 H, m, l-H), 5.93 (1H, d, J = 11 Hz, 7-H), 6.37 (1 H, d, J = 11 Hz, 6-H); UV (EtOH) Am., 266 nm, 250 nm, Am, 225 nm.

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Example 5 .DTD:

Reaction of ketone (8) with methylmagnesium bromide to obtain products (9a) and (9b).

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Ketone (8, R = acetyl, R2 = H) in anhydrous ether is treated with the excess of CH3MgBr (2.85 M solution in ether). The reaction mixture is stirred at room temperature for 30 min, then quenched with aq. NH4CI, extracted with benzene, either and Ch2CI2. The organic phases are 50 washed with dilute NaHC03, dried over MgS04 and evaporated. The mixture of (9a) and (9b) thus obtained is separated by high performance liquid chromatography (6% 2-propanol/hexane, 4.6 mm X 25 cm Zorbax-Sil), to obtain, in order of elution, pure epimers (9a) and (9b). 1(,25dihydroxyvitamin D2 (9a): UV (EtOH) Am,, 265.5 rim, Am.n 227.5 nm; mass spectrum, role 428 (M+, 6), 410 (4), 352 (4), 287 (6), 269 (10), 251 (10), 152 (42), 134 (100), 59 (99); NMR 55 (CDCI3) ( 0.56 (3H, s, 18-H3), 1.01 (3H, d, J=6.5 Hz, 28-H3), 1.04 (3H, d, J=6.5 Hz, 21- H3), 1.14 and 1.18 (6H, each s, 26-H3 and 27-H3), 4.24 (1H, m, 3-H), 4.43 (1H, m, l-H), 5.01 (1H, m, 19-H), 5.34 (3H, broad m, 19-H, 22-H and 23-H), 6.02 (1 H, d, J = 11 Hz, 7- H), 6.39 (1H, d, J = 11 Hz, 6-H).

.DTD:

1o,25-dihydroxy-24-epivitamin D2 (9b): UV (EtOH) Am,, 265.5 nm, Am, 227.5 nm; mass 60 spectrum, m/e428 (M, 13), 410 (9), 352 (7), 287 (11), 269 (15), 251 (13), 152 (52), 134 (100), 59 (97).

.DTD:

Example 6 .DTD:

Conversion of compound (7) to 5,6-trans-1e,25-dihydroxyvitamin D2 compounds (1 la) and 9 GB2 158442A 9 (11b).

.DTD:

Hydrolysis of ketal-intermediate (7, R1 = acetyl, R2 = H) using the conditions described in Example 4 provides the corresponding 5,6-trans-25-ketone of structure ( 10, R1 = acetyl, R2 = H), and subsequent reaction of this ketone with methyl magnesium bromide, using conditions analogous to those of Example 5, gives a mixture of epimers ( 1 la) and ( 1 lb) which 5 are separated by high performance liquid chromatography "(H PLC) to obtain in pure form 1,25dihydroxy-5,6-trans-vitamin D2 ( 1 l a) and 1 e,25-dihydroxy-5,6-trans-2 4-epivitamin D2 ( 1 l b). If required, structure assignment can be confirmed by isomerization to the respective 5,6 cis compounds (9a, 9b) according to known procedures.

.DTD:

5,6-trans-1,25-dihydroxyvitamin D2 ( 1 la): UV (EtOH)}max 273.5 rim, m, 230 rim; mass 10 spectrum m/e428 (M+, 8), 410 (3), 287 (3), 269 (7), 251 (7), 152 (34), 134 (100), 59 (78).

.DTD:

5,6-trans-1e,25-dihydroxy-24-epivitamin D2 (1 lb): UV (EtOH)Am.. 273.5 nm, m., 230 nm; mass spectrum, ree428 (M + 10), 410 (4), 352 (4), 287 (5), 269 (9), 251 (8), 152 (37), 134 (100), 59 (82). 15 Example 7 .DTD:

Preparation of alkyl and aryl analogs of 1,25-dihydroxyvitamin D2 compounds.

.DTD:

By reaction of ketone intermediate (8) (R1 = acetyl, R2 = H) with, respectively, (a) ethyl magnesium bromide 20 (b) propyl magnesium bromide (c) isopropyl magnesium bromide (d) butyl magnesium bromide (e) phenyl magnesium bromide using conditions analogous to those described in Example 5, there are obtained the correspond- 25 ing hydroxyvitamin D2 products having the formula shown below wherein X is, respectively (a) ethyl (b) propyl (c) isopropyl (d) butyl (e) phenyl By like treatment of 5,6-trans-ketone intermediate (10) (R1 = acetyl, R2 = H) with the above listed Grignard reagents, there are GB2158442A 10 Process Scheme I oo..

.DTD:

I R20" ORi HO" H s_. 9_o: 24s_ " 24R 11 GB2158442A 11 Process o-, .CLME:

Claims (5)

CLAIMS .CLME:

1. A compound having the formula ZOy wherein Y is hydrogen, hydroxy or 0-acyl and Z is alkyl.

2. A compound according to Claim 1 wherein Y is hydrogen.

.CLME:

3. A compound according to Claim 1 wherein Y is hydroxy or O-acetyl.

.CLME:

4. A compound according to any one of Claims 1 to 3 wherein Z is methyl.

.CLME:

5. A compound according to Claim 1 wherein Z is methyl and Y is hydrogen.

.CLME:

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1985, 4235.

.CLME:

Published at The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

.CLME: