EP0580774A1 - Vitamin d derivatives comprising a lateral chain expoxide group - Google Patents

Abstract

The present invention relates to compounds derived from vitamin D or one of its analogs having in particular a side chain grafted in position 17 on the D cycle of vitamin D, characterized in that they comprise an epoxide group grafted on said chain lateral, the epoxy group being separated from position 17 by a straight chain of at least two atoms, as well as a process for their preparation and their use as medicaments.

Description

 VITAM INE D DERIVATIVES COMPRISING AN EPOXIDE GROUP

ON THE SIDE CHAIN

 The present invention relates to new vitamin D derivatives, a process for the preparation of these derivatives and their therapeutic applications.

 Vitamin D is one of the most important biological regulators of the metabolism of calcium and mineral and bone phosphorus. In combination with two peptide hormones, calcitonin and parathyroid hormone (PTH), vitamin D is responsible for the control and maintenance of mineral and bone homeostasis.

 Vitamin D is considered today as a steroid hormone in its own right, and more precisely as a prohormone which, after successive metabolism among others in the liver and kidneys, gives rise to a biologically active compound, the

1 alpha, 25-dιhydroxy-vιtamιne D. This last hormone is the major element of a complex endocrine system. It plays a role, not only in the calcium-calcium metabolism by acting on conventional target tissues (intestine, bones, kidneys and parathyroid), but also in the control of important cellular processes (growth, differentiation and various biological functions) in level of a large number of other tissues, normal or cancerous [1-3].

The general term vitamin D applies to both vitamin D ₂ (ergocalciferol) of plant origin and vitamin D (cholecalciferol) found naturally in animals. In humans. these two forms of vitamin D have a very similar biological role. It is therefore of little significance to consider them separately. Vitamins D are defined as seco-steroids, namely molecules chemically characterized by a steroid nucleus with 4 cycles and whose B cycle is open at the level of carbons C-9 and C-10.

In the present application, vitamin D therefore means both vitamin D ₃ and vitamin D ₂ . In humans, the main source of vitamin D is endogenous and in the form of vitamin D ₃ . Vitamin D ₃ is produced from 7-dehydrocholesterol, a precursor synthesized in the epidermis, under the action of ultraviolet radiation from sunlight. Insufficient sun exposure can be compensated by an exogenous supply of vitamins D ₂ and D ₃ .

VITAMIN D STRUCTURE:

Vitamin D ₃ or Cholecalciferol Vitamin D ₂ Vitamin D undergoes a first hydroxylation at position 25, the first metabolic transformation, generating 25-hydroxy-vitamin D (hereinafter 25- (OH) D), one of the main forms of circulating vitamin D. This metabolite has a high affinity for a carrier plasma protein, called DBP ("vitamin D binding protein"), but a low affinity for the intracellular receptor for vitamin D. After hydroxylation in position 1 alpha at the renal level, 25- hydroxy-vιtamιne D is transformed into 1 alpha, 25-dihydroxy-vιtamιne D, or abbreviated 1 alpha, 25- (OH) ₂ D ₃ , which is the biologically active form of vitamin D. This metabolite has a low affinity for DBP and a strong affinity for the intracellular receptor. His blood level is regulated within very narrow limits.

 The metabolism of vitamin D produces a whole series of other metabolites whose physiological role, if it exists, is still poorly defined. 1 alpha-hydroxylase, the enzyme responsible for activating 25- (OH) D, is also present in the placenta, intestine, breast, epidermis (keratinocytes), bone cells (embryonic and normal), certain hematopoietic cells (macrophages and monocytes), as well as granulomatous tissues during granulomatous diseases, such as sarcoidosis).

 The first pharmacological role of vitamin D is the regulation of the metabolism of calcium and phosphorus in conventional target tissues. It stimulates the intestinal and renal absorption of calcium and phosphorus, the bone mobilization of these same minerals (resorbtion or mineralization), while it regulates the secretion of the parathyroid hormone controlling 1 renal alpha-hydroxylase. Thus, an excessive production of vitamin D (accompanied by hypercalcemia, hypercalciuria, and their consequences) is observed in cases of hyper parathyroidism.

 The vitamin D receptor has been identified in many normal tissues, such as the skin, muscles, pancreas, brain, thyroid, placenta, colon, bone (osteoblasts), thymus, and cells of the immune system (monocytes, macrophages, lymphocytes

B and T activated). A large number of cancer cells of all origins have vitamin D receptors; there may be mentioned leukemic cells of monocytic (myeloid) or lymphocytic (lymphoma) origin, melanones and carcinomas of the colon, bone and breast. In these tissues, vitamin D plays an important role in the control of proliferation and cell differentiation, and in the regulation and modulation of the immune system in the same way as estrogens and glucocorticoids, and more recently vitamin A It regulates the growth and differentiation of normal (embryogenesis) and cancer cells (arrest of proliferation and / or induction of cell differentiation). It also behaves as an immunomodulatory substance (eg stimulation of non-specific immunity by monocytes, inhibition of specific lymphocyte immunity).

 Vitamin D plays a fundamental role in many natural biological processes. Any abnormality in the supply or regulation of the metabolism of vitamin D results in more or less significant pathologies. Currently, pathologies associated with vitamin D are classified as deficiencies or excess of vitamin D.

 Vitamin D deficiencies or deficiencies are due to insufficient sunshine associated with a deficit of exogenous intake by food or during malabsorption syndrome, abnormal metabolism of vitamin D, or when the tissues are resistant to its action . Metabolic abnormalities are associated with related disorders

(a) the production of 25- (OH) D (liver disease, prolonged use of anticonvulsants or corticosteroids);

(b) to the production of 1 alpha, 25- (OH) ₂ D ₃ , by absence or deficiency of hydroxylation in the 1 alpha position (case of type I-resistant vitamin rickets), or

 (c) to its biological action, by the absence or deficiency of cellular vitamin D receptors (case of vitamin II resistant rickets).

Vitamin-resistant rickets is hereditary. The metabolism of vitamin D can also be disturbed during various pathologies, and in particular, familial hypophosphatemic rickets (renal tubular deficit in phosphate transport), chronic renal failure (renal osteodystrophy), diabetes mellitus (increased incidence of osteopenia, osteoporosis and fractures), hypoparathyroidism and certain cancers (multiple myeloma), or through pharmacological interactions, especially with anti-epileptic drugs and corticosteroids.

 The clinical manifestations of these vitamin D deficiencies appear most clearly at the bone level: rickets in children and osteomalacia in adults, and perhaps participation in the phenomena of osteoporosis. There are other more discreet associated disorders, for example an immunodeficiency in rachitic children, a higher incidence of certain cancers, in particular of the colon, associated with a deficiency in calcium and vitamin D, or vascular and endocrine disorders.

Excess vitamin D occurs mainly during vitamin D poisoning or during ectopic production of active metaboiites, for example during ganulomatous diseases (sarcoidosis). It is the same during hyperparathyroidism, stimulating the excessive production of 1 alpha25- (OH) ₂ D ₃ .

The usual deficiencies in vitamin D are easily corrected by the exogenous supply of vitamin D. The active derivatives of vitamin D and in particular 1 alpha, 25- (OH) ₂ D ₃ , must be administered if the metabolism is abnormal, especially in kidney failure. These have a very narrow therapeutic index, so that vitamin intoxication is frequent during their administration. The 1 alpha, 25- (OH) ₂ D ₃ on the other hand has a short half-life which often justifies two daily doses. In addition, prolonged treatments are accompanied by hypercalcemia, hypercalciuria, and their consequences, especially in the liver and kidneys. The search for derivatives with a different pharmacokinetic profile and a more favorable therapeutic index therefore remains current.

The specific regulatory role of vitamin D, particularly in terms of cell proliferation and differentiation, can be used to control certain pathologies which are not directly related to a vitamin D metabolism disorder. The development of new analogs of vitamin D opens perspectives in the field of recognized applications, such as secondary hyperparathyroidism [4-6], skin pathologies, among others psoriasis [7-12], dyskeratoses and acne, osteoporosis, among others postmenopausal osteoporosis, senile or due to an excess of corticosteroids [13,14], or potential applications in endocrinology, such as the regulation of insulin secretion by the pancreas, in immunology, such as autoimmune diseases or immunoregulation, for example during organ transplants [15,16], or in oncology, such as leukemia, lymphomas, myelodysplastic syndromes [17-19].

 The biomedical potential of a vitamin D analog will essentially depend on the possibility of distinguishing or dissociating the different forms of biological activity, in particular between the calcifying effect and the cellular effect.

 An object of the present invention is to make certain modifications to the side chain of vitamin D so as to obtain such a distinction, in particular by retaining a biological activity similar to or even greater than that of the natural hormone, while reducing the 'calcifying effect, especially on bone tissue.

1 alpha, 25- (OH) ₂ D ₃ and its precursor, 1 alpha-OH-D ₃ are used in renal failure and osteoporosis [13, 14]. Calcipotriol, or 22-ene-24-cycopropyl-1 alpha, 24- (OH) ₂ D ₃ from Léo Pharmaceutica [1 1,12], has also been proposed for the treatment of psoriasis.

Other derivatives are under research and development. Their therapeutic use underlines the growing interest in vitamin D analogues in human medicine.

 If the results obtained to date with the first analogs of synthesis of vitamin D, mentioned above, are interesting and encouraging, their therapeutic effectiveness remains however still limited.

 An object of the present invention is to provide new analogs of vitamin D making it possible to improve the biological selectivity and the therapeutic index of analogues of vitamin D.

More particularly, an object of the present invention is to provide new analogs making it possible to modulate or dissociate the different biological activities of vitamin D on the target cells and, for example, providing compounds active on cell differentiation but not very active on the phospho-calcium metabolism making it possible to increase the administrable doses and the therapeutic index for the therapeutic indication concerned.

 The present invention therefore relates to derivatives of vitamin D or one of its analogs, having a side chain grafted in position 17 on the D cycle of vitamin D, said side chain comprising an epoxy group separated from position 17 by a linear chain of at least two atoms, in particular two carbon atoms.

 In particular, the compound corresponds to the formula:

in which

 - V represents a residue of vitamin D or one of its analogs whose position 17 is vacant;

- X grafted in position 17 - of V represents a hydrocarbon chain, in particular aikylated, of 2 to 15 carbon atoms optionally substituted or modified, in particular being able to comprise, in one or more positions, one or group (s)

 . hydroxyl, methyl, ethyl, halogen, preferably fluorine,

. ester, in particular a group R ¹ COO with R ¹ which represents a linear or branched C ₁ to C ₇ alkyl or alkoxy, saturated or unsaturated, optionally substituted in particular by one or more hydroxy or halogen group (s), preferably fluorine,

. ether, in particular a group R ¹ -O with R ¹ which represents a linear or branched C ₁ to C ₇ alkyl or alkoxy, saturated or unsaturated, optionally substituted by one or more hydroxy or halogen group (s),

. oxo in ketone form,

. a ring or heterocyle, in particular saturated or unsaturated, aromatic or heteroaromatic cycloalkyl which can carry all the groups and modifications mentioned above, and / or said chain X which may contain, instead of one or more of its carbon atoms, an oxygen, nitrogen or sulfur atom,

said X chain being able to be unsaturated, with one or more double (s) or tnple (s) Iιaιson (s) carbon-carbon, this unsaturated chain being able to carry all the groups and modifications mentioned above, and

 - said chain and the different groups located on the chain can adopt all the isomeric forms,

- the epoxy group

 can be grafted onto any one of the 13 carbon atoms of X, in particular at its end, an epoxide group in which

R ₁ , R ₂ and R ₃ , which may be identical or different, represent a hydrogen, a C ₁ to C ₁₀ alkyl group, linear or branched, saturated or unsaturated, optionally substituted with one (or more) group (s) halogen, hydroxy, cycloalkyl, also optionally substituted with halogen or hydroxy groups;

. R ₁ and R ₂ can be part of the same cycle, such as carbocycle or heterocycle, and in this case R ₃ has the same meaning as above. . R ₁ and R ₃ may be part of the same cycle, such as carbocycle or heterocycle, and in this case R ₁ has the same meaning as above; . the different isomeric forms at the epoxide level being possible.

 The term “residue of vitamin D or analogs of vitamin D (V)” is understood to mean a compound of which the basic structural skeleton has the formula:

and the complete formula of which may have substitutions in all positions other than position 17 of the D cycle.

 In particular, V can represent a remainder

- analogues having a C _{1 1} derivative which have been described by the applicant in EP 341 158

- derivatives having a double bond between C _{1 6} -C _{1 7} described in US 199167 and EP 050325

- compounds with a heterocycle between C ₆ and C _{1 0} which have been described in EP 81 793, EP 78704

- Derivatives having various C ₃ and C ₁ derivations which have been described in WO 90/10620.

 The compounds according to the invention will most often correspond to the formula

in which X, R ₁ to R ₃ have the meanings given above and - represents a single bond or a double bond;

- A represents a hydrogen, a methyl or the methylene group = CH ₂ ; - Y identical or different represents H, OH, an ester group, in particular R ¹ COO, or ether in particular R ¹ O, with R ¹ which has the significance given above. Among these, the compounds in which X represents an alkyl chain of 2 to 6 carbon atoms are preferred, whereof a carbon atom is replaced by an oxygen atom, optionally substituted, in particular by one or more methyl group (s) , hydroxyl, ether, in particular a group R ¹ O, and / or unsaturated with a carbon or carbon double or triple bond, the epoxy group being grafted to the end of the alkyl chain X, R ₁ , R ₂ and R ₃ , may be the same or different, representing a hydrogen, a hydroxy, an alkyl group, in particular a methyl or ethyl or a hydroxyalkyie.

 In particular, mention may be made of the compounds which correspond to formula II

and in particular to the four pure or mixed isomeric forms

in which Z represents a saturated or unsaturated alkyl chain of 0 to 3 carbon atoms, optionally substituted or modified as mentioned for X previously, in particular substituted by a hydroxy, an alkyl, such as methyl or ethyl, on one or more carbon atoms, and R ₁ to R ₃ and R ¹ have the meanings given above, the epoxide group being grafted onto the end of 7.

 Among the latter are the compounds according to formula II, in particular IIa or IIb with

R ₁ R ₂ R ₃ Z

CH ₃ HH -CH ₂ -CH ₂

CH ₃ HH -CH ₂ -CHOH-

H CH ₃ CH ₃ -CH ₂ -

HHH -C (CH ₃ ) ₂ -

CH ₃ HH -CC-

The compounds according to the invention can be prepared by methods known to those skilled in the art.

 The present invention also relates to a process for the preparation of a compound according to the invention, characterized in that the anion obtained from a compound is reacted with the basic structural skeleton of which has the formula IV

and n-butyliithium, with a compound whose basic structural skeleton has the formula III

in which the reactive functions grafted onto the skeletons of III and IV are optionally protected and

X, R ₁ , R ₂ , R ₃ , whose reactive functions are possibly protected, have the meanings given previously,

then said reactive functions are optionally deprotected, in particular from X, R ₁ , R ₂ , R ₃ and hydroxyl in positions 1 and 3.

 This type of coupling is described in the literature [28]. Similarly, the synthesis of derivatives of formula IV has been described [29].

 In particular, the derivatives of formula Ib in which Y represents OH or OR can be obtained from

The compound of structure III ′ can be obtained by several routes, in particular those included in the diagram below.

 A first sequence comprises the following stages: a) reacting a compound whose basic structural skeleton has the formula VI in which

 Tos is the tosylate group,

R ² is hydrogen or an alcohol protecting group, and

X has the meaning given above with optionally the reactive groups, in particular hydroxy in protected form, and

W and Z 'represent hydrocarbon chains which are parts of X, such that -X represents -W-Z', the chain X therefore being constituted by the chains W and Z 'joined at one of their ends, W and Z' therefore having meanings given for X, in particular Z ′ which can represent Z, of which, where appropriate, the reactive groups, such as hydroxy, are protected,

 with an organometallic derivative of formula VII in which Met is lithium or halogenomagnesium,

b) then the olefin thus obtained is epoxidized, and

c) after possible deprotection of the derivative whose basic structural skeleton has the formula VIII, the hydroxy function is oxidized to ketone.

A second sequence includes the following steps:

a) reacting the skeleton compound VI with an organometallic derivative of formula IX, followed by hydrolysis which releases the ketone function,

b) which is then reacted with sulfur ylides (sulfuryhdes). and c) after optional deprotection of the derivative VIII, the oxide is carried out as above.

It is also possible to use one or other of the following sequences, in which an organometallic derivative of formula X is reacted with tosylate XI or XII and then to carry out the respective epoxidations as described previously. This latter route will be advantageous when W (and therefore X) is a hydrocarbon chain in which a carbon atom is replaced by oxygen, sulfur or nitrogen. In this case the organometallic derivative X will preferably be prepared from Xa, where the hydrogen marked H ⁺ is hey with oxygen, sulfur or nitrogen, by deprotonation. Otherwise X can be prepared from a halogen drift Xb by transmetailation.

It should be noted that in place of a tosylate in the derivatives described above (VI. XI and XII) another leaving group, for example iσdure, can be used.

In VII, IX, XI and XII, the groups

can be grafted onto any position of the chain Z ′, in particular at its end.

Different alternative routes for preparing the compounds will emerge in the light of the examples which follow

 The present invention also relates to the use as a medicament of compounds according to the invention.

 The vitamin D analogs according to the invention, characterized by the presence of an epoxide function in the side chain, constitute the first group of modifications of this type made to vitamin D for therapeutic purposes. The epoxide function advantageously replaces the hydroxyl group characteristic of the active form of vitamin D, and located in position 25. Indeed, until the present invention, all the biologically active analogs of vitamin D had at least one hydroxyl function in the side chain, in particular in position 25. It has been discovered according to the present invention that the epoxide function located on the side chain of vitamin D makes it possible to obtain a biologically active analog without the obligatory presence of a hydroxyl function at the level of the side chain. Furthermore, the epoxide function gives particularly advantageous biological properties to the corresponding products, which do not have this function. It appears, in fact, that the epoxy group confers in itself a biological activity and that this activity is different from that conferred by the hydroxy group.

On the one hand, the epoxide function confers on 1-alpha-hydroxy-vitamin D, an inactive metabolite of vitamin D, specific biological activities characteristic of the active form, 1 alpha, 25- (OH) ₂ D ₃ . For example, the derivative 1 alpha hydroxy, 25, 26-epoxy- l -vιtamιneD ₃ (com posed 24) increases by more than 100 times the capacity of l alpha-OHD ₃ to differentiate human leukemia cells (HL-60) .

 On the other hand, the epoxide function confers a dissociated biological property compared to the usual analogs of vitamin D, having a hydroxyl function in position 25 of the side chain.

In terms of cellular properties of the differentiation type, the epoxide analogues generally behave like the active metaboiite of vitamin D. They also appear to be active to clearly more active than 1 -alpha, 25- (OH) ₂ D ₃ .. Mention may in particular be made of the differentiation of human leukemia cells and of epidermal cells (human keratinocytes) as well as the antiprofferative effect on tumor cells, for example MCF-7.

 With regard to the calcium-calcium metabolism, the calcium-forming effect of the analogues is considerably reduced (marginal activity) or even non-existent in the rachitic chicken model. They also appear to be much less able to stimulate the secretion of osteocalcmes by human osteoblastic cells in culture.

 This reduction in side effects of the hypercalcemic type, observed in the case of epoxide analogs, does not prevent the effectiveness of the compounds in the context of osteoporosis. Indeed, the therapeutic effect in these circumstances - independent of the calcifying effect - then results from the differentiation effect on bone type cells.

 Thus, the epoxide derivation makes it possible to properly dissociate the calcifying effect from other forms of biological activity. For example, the epoxide analogs and in particular the derivative 26a: (245, 25R) -l alpha.24 dihydroxy - 25,26-epoxy, Vitamin D, are capable of stimulating the differentiation of leukemic or epidermal cells without however inducing a calcifying effect . The significant reduction in the calcifying effect gives these analogues definite advantages compared to vitamin D or its active metabolite, in particular to increase the concentration of compound which can be administered without influencing the phosphocalcic metabolism, and thereby d '' increase the therapeutic index in many applications.

 The present invention therefore also relates to the application of the compounds according to the invention as medicaments.

 The present invention therefore more specifically relates to the use of this medicament in particular for the treatment and / or prophylaxis

_ pathologies of the skin, inter alia psoriasis, dyskeratoses, acne, alopecia and aging of the skin including the effect of sun and light radiation;

 - secondary hyperparathyroidism;

- cancers including leukemias, lymphomas, syndromes, myelo-dyspiasic syndromes, melanomas, breast, lung or colon cancer and their metastases: - autoimmune diseases including endoscinopathies such as diabetes mellitus; neurological pathologies, such as multiple sclerosis and systemic diseases, such as lupus erythematosus, glomerulonephritis;

- inflammatory processes, such as rheumatoid arthritis, arthritis and asthma;

 - osteoporosis, including osteoporosis seniie, that which accompanies diabetes mellitus or corticosteroid treatment;

 - high blood pressure.

- the modulation of the immune system (suppression of the proliferation of lymphocytes, differentiation of monocytes, etc.) useful for treatment and prophylaxis in the case for example of autoimmune diseases, inflammatory processes, as well as in the case of transplantation of 'organs. The compounds according to the invention can in fact be used to prevent rejection of grafts used alone or in combination with other compounds, such as cyclosporine, FK 506, etc.

 - renal failure;

 Other characteristics and advantages of the invention will emerge in the light of the description and the examples which follow.

In the examples which follow, the derivatives of formula V have in particular been obtained according to one of the routes generally mentioned in scheme 1b below:

We can distinguish three stages:

 (a) the introduction of a fragment of the side chain containing a function, possibly protected, which must allow the introduction of the epoxide; the introduction of the fragment is advantageously done by substitution of the tosylate group in le, method described in the literature [30];

 (b) the introduction of the epoxide which can be carried out from a type A olefin by one of the conventional epoxidation methods or from a type A ketone using for example yides in which case the introduction of part of the chain jointly gives the epoxy;

 (c) after possible deprotection of the hydroxyl group on the cycle, oxidation of the latter to ketone. It should be noted that, in general, the epoxide formed will be present in two isomeric forms which it may be useful to separate.

 The isomeric forms at C-20 (see structure Ile, I here) are prepared in the same way but starting from the tosylate which is obtained from the corresponding isomeric primary alcohol 1b. The latter can be obtained from the by the following sequence:

 (a) oxidation of the primary alcohol therein, for example by pyridinium hydrobromide perbromide;

 (b) isomerization of the aldehyde 2a with a base such as diazabicylo- undecene;

 (c) reduction of the mixture of aldehydes 2a and 2b with sodium borohydride and separation of the alcohols la and lb.

 The aldehyde 2a can also be obtained by direct oxidation of tosylate le in dimethyl sulfoxide.

 In the examples and Scheme 2 below, the synthesis of the V precursors of vitamin D derivatives is explained, according to the invention.

 Epoxide 5, obtained as a mixture of diastereomers

5a and 5b, is obtained from tosylate le. The latter is prepared from alcohol la with tosyl chloride in pyridine. Alcohol is the result of ozonolysis, followed by reduction by sodium borohydride, vitamin D- or acetate of vitamin D2 according to a process described in the literature [31]. Tosylate is then coupled The isomeric forms at C-20 (see structure Ile, Ild) are prepared in the same way but starting from the tosylate which is obtained from the corresponding isomeric primary alcohol 1b. The latter can be obtained from the by the following sequence:

 (a) oxidation of the primary alcohol to 1a, for example by pyridinium hydrobromide perbromide;

 (b) isomerization of the aldehyde 2a with a base such as diazabicyio- undecene;

 (c) reduction of the mixture of aldehydes 2a and 2b with sodium borohydride and separation of the alcohols 1a and 1b.

 The aldehyde 2a can also be obtained by direct oxidation of tosylate le in dimethyl sulfoxide.

In the examples and Scheme 2 below is explained the synthesis of the precursors V of derivatives of vitamin D ₃ according to the invention.

 Epoxide 5, obtained as a mixture of diastereomers

5a and 5b, is obtained from tosylate The latter is prepared from alcohol la with tosyl chloride in pyridine. Alcohol is the result of ozonolysis, followed by reduction by sodium borohydride, vitamin D ₂ or acetate of vitamin D ₂ according to a process described in the literature [31]. The tosylate is then coupled with the organomagnesium derivative of 4-chloro-2-methyl-1-butene in the presence of Li ₂ CuCl ₄ according to the process described for this derivative in the literature [32]. The epoxidation of the olefin 3 thus obtained is carried out in a conventional manner with m-chloroperbenzoic acid in dichloromethane at room temperature. The mixture of the two epoxides Ψa and Ψb thus obtained is advantageously oxidized with pyridinium dichromate in dichloromethane.

The epoxide 11a, having an additional function in the side chain, can be selectively prepared from olefin 3. After protection of the secondary alcohol in the form of timethylsiiyh ether, position 24 in the chain lateral is oxidized by selenium dioxide in the presence of tert-butyl hydroperoxide in dichloromethane. The resulting mixture of diastereomeric alcohols 7a and 7b is not separated at this stage. Indeed the epoxidation according to the Sharpless method [33] allows in the present case, using in the presence of (-) - dnsopropyl-L- tartrate of tert-butylhydroperoxide and T ₁ ( ₁ -PrO) ₄ , the transformation selective alcohol 7a to epoxy 8a, leaving the alcohol 7b unchanged. The latter can optionally be used then in an epoxidation as decreased for the olefin 3. After deprotection of the secondary alcohol, the diol 9a is selectively oxidized to the hydroxyl attached to the ring. Finally, the hydroxyl function in the side chain of ketone 10a is protected in the form of trimethylsilyh ether (1 1a) with a view to its coupling.

In an analogous manner the protected epoxy ketone 15b, a stereoisomer of 11a, is prepared starting from the olefin 6. After the allylic oxidation, the mixture of alcohols 7a, 7b is deprotected. The Sharpless oxidation this time is carried out on the mixture of diols 12a, 12b. In the presence of (-) - dusopropyl-D-tartrate, tert-butylhydroperoxide and Ti (IV) ιsopropoxιde the epoxidation takes place selectively on 12b, leaving 12a unchanged. The epoxide 13b is then oxidized and the free hydroxy group in ketone 14b is protected in the form of trimethylsilic ether for the coupling of 15b. The synthesis of epoxides 18a, 18b, as well as 18'a and 18'b is also carried out starting from tosylate le. When the latter is treated with the Grignard derivative obtained from isopentenyl chloride in tetrahydrofuran in the presence of Li ₂ Cu (II) Cl _4, a mixture of the expected olefin 16 and an isomeric olefin is obtained. 16 '. The latter is not an important product when iodide is used in the described step as a leaving group instead of a tosylate. After conventional epoxidation the mixture of epoxides is obtained which can be separated. In this way the epoxidation of the secondary alcohol can be carried out on the derivatives 17a, 17b on the one hand, and on the derivatives 17'a, 17'b, on the other hand. Ketones 18a, 18b and 18'a, 18'b can be used directly in the coupling step.

 Finally acetylene 22a, 22b is obtained from the tosylate by substitution with the lithiated derivative obtained from the acetal of 3-butyn-2-one. After deprotection of the acetal in 19, the ketone is treated with a ylide obtained from trimethylsulfonium iodide. The diastereomeric epoxide 21a, 21b is oxidized and the corresponding ketones 22a, 22b can be coupled directly.

The synthesis of derivatives II of vitamin D ₃ by coupling of derivatives V with the anion of derivative IV is carried out according to scheme 3: The coupling of ketones having the epoxide function in the side chain such as 5a / 5b and 11a with the anion of the derivative IV leads to the protected derivatives such as 23a / 23b and 25a, respectively. The elimination of the protective groups of the coupling derivatives finally leads to the obtaining of the alcohols derived from formula II.

 An example is the condensation of the lithium salt, obtained from phosphonate IV with n-butyllithium in THF at -78 ° C with the mixture of diastereomers 5a and 5b, leading to the mixture of trienes 23a and 23b. The deprotection of the silylated ether groups is advantageously carried out with tetrabutylammonium fluoride. In the case of epoxide 11a, the analogous coupling leads to 25a and, after deprotection, to triol 26a.

In a completely analogous manner the epoxide 15b leads via 27b to the triol 28b. The reaction of mixtures of diastereomers 18a and 18b, 18'a and 18 * b, as well as 22a and 22b, lead after coupling and deprotection to mixtures of diols 30a and 30b, 30'a and 30'b, and 32a and 32b, respectively.

EXAMPLE 1 Synthesis of epoxy alcohols 4a, 4b

To a solution of 3 (0.16 g, 0.61 mmol ^ in anhydrous dichloromethane (7 ml) was added m-chloroperbenzoic acid (mCPBA, 0.235 g, 1.36 mmol, 2.2 equivalent) and the solution was stirred for one hour at room temperature under an argon atmosphere, potassium carbonate was added, stirring was continued for 10 minutes and the reaction mixture was filtered through a ht of Merck Kieselgel 60 and celite using the n-hexane / ethyl acetate mixture (7: 3) The filtrate was concentrated under reduced pressure and the oily residue was purified by HPLC on a column of silica 10 μm with n -hexane / ethyl acetate (8: 2) as eluent, to give the mixture of diastereoisomers 4a and 4b (0.146 g, 0.52 mmol, 86%) as a white solid.

 Characteristics: Rf (n-hexane / ethyl acetate, 7: 3): 0.31.

Spectroscopic data of 4a, 4b: IR (KBr-film): 3424 (s), 2943 (s), 2872 (s), 2285, 1461, 1444, 1390, 1 373, 1266, 1 170, 1066, 995, 943 , 898, 887, 858, 835, 802, 737 and 702 cm ^{- 1} ; ¹ H NMR (COCl ₃ , 360 MHz): 4.07 (1 H, q, 2.6 Hz), 2.61 (1H, dd, 4.9, 2.9 Hz), 2.57 (1H, d, 4.9 Hz), 1.99 (1 H, m), 1.82 (3H, m), 1.30 (3H, s), 0.92 (3H, s) and 0.90 (3H , d, 6.5 Hz) ppm; MS: m / z to 262 (1), 247 (2), 234 (1), 180 (1), 179 (4), 162 (4), 1 51 (9), 136 (14), 125 (16 ), 1 1 1 (100), 96 (27), 81 (40), 67 (36) and 55 (75).

EXAMPLE 2 Synthesis of epoxy ketones 5a, 5b

To a solution of 4a, 4b (0.146 g, 0.52 mmol) in anhydrous dichloromethane (9 ml) was added pyridinium dichromate (PDC, 0.494 g, 1.31 mmol, 2.5 equivalent) and a catalytic amount of pyridinium para-toluenesulfonate (PPTS) and the suspension was stirred for 4 hours at room temperature under an argon atmosphere. Of ether was added (from 10 ml) and stirring continued for 5 minutes, the reaction mixture was filtered through one ht of Merck Kieselgel 60 and cehte using ether. and the chromium salt precipitates were washed several times with ether and then filtered. The mixed filtrates were concentrated under reduced pressure and the residue was purified by HPLC on a 10 μm silica column using as eluent n-hexane / ethyl acetate (85: 15). The mixture of diastereoisomers 5a and 5b (0.139 g, 0.5 mmol, 96%) was thus obtained in the form of an oil. Characteristics: Rf (n-hexane / ethyl acetate, 7: 3): 0.35.

Spectroscopic data of 5a, 5b: IR (KBr-film): 3034, 2956 (s), 2873 (s), 1714 (s), 1456, 1378, 1 307, 1255, 1234, 1 187, 1 152, 1 107 , 1056, 943, 902, 838, 795, 737 and 703 cm ^{- 1} ; ¹ H NMR (CDCl ₃ , 360 tMHz): 2.61 (1H, dd, 4.9, 2.8 Hz), 2.58 (1H, d, 4.9 Hz), 2.44 (1H, dd , 1 1.6, 7.5 Hz), 2.26 (2H, m), 2, 12 (1H, ddd, 12, 4.1, 2.5 Hz), 2 (1H, m), 1, 90 (2H, m), 1.78 (1H, m), 1.31 (3H, s), 0.96 (3H, d, 6.1 Hz), and 0.63 (3H, s) ppm; MS: m / z to 278 (M ^.- , 1), 263 (2), 250 (2), 235 (2), 204 (2), 177 (4), 159 (4), 125 (24), 1 1 1 (36), 85 (24), SI (52). 67 (39) and 55 (100).

EXAMPLE 3 Syntheses of 25 (S) - 1 alpha-hydroxy-25,26-epoxy-vιtamene D ₃ (24a) and 25R-1 alpha-hydroxy-25,26-epoxy-vιtamene D ₃ (24 b).

A solution of IV (0.053 g, 0.091 mmol, 1.3 equivalent) in anhydrous tetrahydrofuran (0.5 ml) was placed under an argon atmosphere (1.1 bar), cooled to -70 ° C and n -butylhthium (2.41 M solution in n-hexane, 0.037 ml, 0.087 mmol) was added. The resulting dark solution was stirred for 30 minutes. Ketones 5a and 5b were then added dropwise (0.02 g, 0.072 mmol) dissolved in anhydrous tetrahydrofuran (0.9 ml). The mixture was stirred at -70 ° C for 1.5 hours and then allowed to return to room temperature over a period of two and a half hours. Two or three drops of water were added to the red solution and most of the solvents were removed under a stream of argon. A saturated sodium bicarbonate solution (2 ml) was added and extracted three times with diethyl ether (2 ml), the mixed extracts were filtered through a ht of Merck Kieselgel 100 (35-70 mesh) and the solvent was removed under reduced pressure. The residue was rapidly chromatographed on a 10 μm silica HPLC column with n-hexane / ethyl acetate (85:15) as eluent. The oil obtained (mixture of 23a and 23b) was immediately taken up in anhydrous tetrahydrofuran (0.3 ml), tetrabutylammonium fluoride (TBAF, 1 M solution in tetrahydrofuran 0.255 ml) was added and the solution was stirred for 15 hours at room temperature under an argon atmosphere, protected from light. The solvent was removed under a stream of argon and the residue was chromatographed on Merck Kieselgel 60 with dichloromethane / methanol (9: 1) as eluent. Additional purification by HPLC (10 μm of silica, dichloromethane / methanol (92.5: 7.5)) made it possible to obtain the mixture of diastereoisomers 24a and 24b (0.019 g, 0.046 mmol, 64%). Characteristics: Rf (dichloromethane / methanol 9: 1): 0.41.

Spectroscopic data of 24a, 24b: UV (MeOH) ² max = 261 nm; IR (KBr-filrn): 3380 (s), 3048, 2946 (s), 2870 (s), 1644, 1446, 1377, 1266, 1218. 1148, 1055, 957, 898, 799, 737 and 703 cm ^-1 ; ¹ H NMR (CDCl ₃ , 360 MHz): 6.3S (1H, d, 11.2 Hz), 6.01 (1H, d, 11.2 Hz), 5.32 (1H, m), 5 ( 1H, m), 4.44 (1H- dd, 7, 4.3 Hz), 4.22 (1H, ddd, 10, 7, 4 Hz), 2.82 (1H, dd, 11.5, 3 , 5 Hz), 2.61 (1H, dd, 4.8, 2.3 Hz), 2.57 (1H, d, 4.8 Hz), 2.31 (1H, dd, 13.4, 6 , 6 Hz), 1.81-2.05 (4H, m), 1.31 (3H, s), 0.93 (3H, d, 6.4 Hz) and 0.54 (3H, s) ppm ; MS: m / z to 415 (M ^{, +} , 1, 2), 397 (2), 378 (2), 287 (1), 267 (2), 251 (3), 197 (3), 171 (5 ), 152 (24), 134 (60), 105 (31), 91 (42), 81 (40), 79 (40), 67 (35) and 55 (100).

EXAMPLE 4 Synthesis of Alcohols 7a and 7b

To a solution of 3 (600 mg, 2.27 mmol) and N- (trimethyl- sιlyl) -ιmιdazole (953 mg, 6.81 mmol, 997 μl) in anhydrous CH ₂ Cl ₂ (8 ml) was stirred at room temperature under a nitrogen atmosphere for 3 hours. After concentration, a residue was obtained which was directly chromatographed (hexane / EtOAc, 16: 1) to give 6 as an oil (672 mg, 88 96). Characteristics: Rf (hexane / EtOAc 8: 2): 0.95.

Spectroscopic data of 6: ¹ H N'MR (CDCl ₃ , 360 MHz): 0.05 (9H. S), 0.88 (3H, s), 0.89 (3H, d, 6.64 Hz), 1, 71 (3H, s), 3.99 (1H, m), 4.66 (1H, bs), 4.68 (1H, bs) ppm.

A mixture of selenium dioxide (33 mg, 0.30 mmol), t-butylhydroperoxide (90%, 90 mg, 0.90 mmol) and anhydrous CH ₂ CI ₂ (4 ml) was stirred at 25 ° C for a half hour. A solution of 6 (200 mg; 0.60 mmol) in anhydrous CH ₂ CI ₂ (4 ml) was added over several minutes. The resulting mixture was stirred at 25 ° C under nitrogen for half an hour. Stirring was continued at about -20 ° C for 22 hours. The reaction was carried out until reaching room temperature, methyl sulfide (1 ml) was added, the resulting mixture was stirred at 25-30 ° C for 5 hours. The reaction mixture was filtered through a small silica gel, the concentration of the filtrate gave a residue which was directly chromatographed (hexane / EtOAc 16: 1) to give 6 (9 mg,

4.5%) and a mixture of diastereomers 7a and 7b in the form of an oil (63 mg, 30%).

Characteristics: Rf (hexane / EtOAc, 9: 1): 0.36. [a] ²⁶ D + 45.83 ° (c 1.857,

CHCI ₃ ).

Spectroscopic data of 7a and 7b: H NiMR (CDCI ₃ , 360 MHz): 0.04

(9H, s), 0.87 (3H, s), 0; 90 (3H, d, 6.51 Hz), 1.72 (SH, s), 4 (2H, m), 4.83 (1H , d), 4.92 (1H, m) ppm.

EXAMPLE 5 Synthesis of alcohol 7b and epoxide 8a

4 A sieves were added to a solution of 7a, 7b (90 mg, 0.256 mmol) and (+) - dusopro-pyltartrate (9 mg, 0.038 mmol) in anhydrous CH ₂ CI ₂ (1.5 ml) reactivated powder (27 mg). The stirred mixture, kept under a nitrogen atmosphere, was cooled from -10 to -20 ° C, treated with titanium (IV) isoproproxide (7.4 mg, 0.026 mmol) and kept stirring for 30 minutes at -20 ° C. The reaction was then treated with a solution of tert-butyl hydroperoxide in isooctane (7 M, 0.179 mmol, 26 μl, dried with freshly activated 3 Â pellets for 30 minutes before addition) and poured using a syringe. The reaction was kept under stirring at around -20 ° C for 27 hours. An aqueous solution of ferrous sulfate and tartaric acid (2 ml) was cooled to 0 ° C and treated dropwise with the reaction mixture. The two-phase mixture was stirred for 10 minutes and the aqueous solution extracted with two portions of ether (4 ml). The organic phase was treated with 2 ml of solution pre-cooled to 0 ° C 30% NaOH in saturated brine. The two-phase mixture was stirred vigorously for 1 hour at o ° C and, after dilution with water (3 ml), the phases were separated and the aqueous layer was extracted with ether (2 × 10 ml ). The mixed organic phase was washed with brine, then dried over MgSO ₄ . After filtration and concentration, a residue was obtained which was separated by HPLC (hexane / EtOAc, 9: 1) to give a pure 7b oil (27 mg) and crude product 8a. The latter was purified by HPLC (hexane / EtOAc, 9.5: 1) to give pure product 8a in the form of white crystals (38 mg).

Compound 7b:

Characteristics: Rf (hexane / EtOAc, 8: 3) = 0.72; [a] ²² D + 56.05 ° (c 1, 140, CHCl ₃ ). Spectroscopic data: IR (KBr-Film): 3360 (s, br), 3072 (w), 1650, 908 (s) cm ^{- 1} ; ¹ H NMR (360 MHz, CDCl ₃ ): 0.05 (9H, s), 0.88 (3H, s),

0.90 (3H, d, 6.53 Hz), 1.72 (3H, s), 3.99 (2H, m), 4.83 (1H, t), 4.93 (1H, t) ppm ; MS: m / z 334 (2), 309 (3), 262 (1), 223 (8), 197 (12), 183 (75), 73 (100).

Compound 8a:

Characteristics: Rf (hexane / EtOAc, 8: 3) = 0.55; [a] ²² D + 46.81 ° (c 1, 1 77, CHCl ₃ ); mp: 65-66 ° C. Spectroscopic data: IR (KBr-Film): 3479 (s, br), 1250 (s), 839 (s), 745 cm ^{- 1} ; ¹ H NMR (360 MHz, CDCl ₃ ): 0.04 (9H, s),

0.87 (3H, s), 0.91 (3H, d, 6.57 Hz), 1.34 (3H, s), 2.61 (1H, d, 4.77 Hz), 2.89

(1H, d, 4.77 Hz), 3.56 (1H, m), 3.99 (1H, m) ppm; MS: m / z 368 (M ^+. , 1), 295

(2), 223 (3), 197 (11), 183 (66), 73 (100). EXAMPLE 6 Synthesis of Diol 9a

A solution of 8a (34 mg, 0.02 mmol) and tetrabutylammonium fluoride (1M solution in THF, 0.46 mmol, 460 μl) in THF (2 ml) was stirred at room temperature for 2 hours and half. After removing the THF under reduced pressure, the residue was treated with ether and the mixture washed with brine and then dried over MgSO ₄ . After filtration and concentration, a residue was obtained which was chromatographed (hexane / EtOAc, 6: 4) to give an oily and viscous compound 9a (26 mg, 96%).

 Characteristics: Rf (hexane / EtOAc, 6: 4) = 0.38.

Spectroscopic data of 9a: ¹ H NMR (360 MHz, CDCl ₃ ): 0.92 (3H, d, 6.26 Hz), 0.92 (3H, s), 1.34 (3H, s) 2.60 (1H, d, 4.78 Hz), 2.88 (1H, d, 4.78 Hz), 3.55 (1H, m), 4.07 (1H, m) ppm.

EXAMPLE 7 Synthesis of Epoxyketone 10a

A mixture of 9a (25 mg, 0.084 mmol), pyridinium dichromate (47 mg, 0.125 mmol) and anhydrous CH ₂ C l ₂ (2 ml) was stirred at room temperature under nitrogen for 2 hours. The mixture was chromatographed (hexane: EtOAC / CH ₃ COCH ₃ , 6: 4: 0.5) to give the crude product 10a which was purified by HPLC (hexane / EtOAc, 6: 4) to give oil pure 10a (20 mg, 81%).

Characteristics: Rf (hexane / EtOAc, 6: 4) = 0.36.

Spectroscopic data of 10a: IR (KBr-Film): 3444 (s, br), 1709 (s), 1236, 906, 812 cm ^{- 1} ; ¹ H NMR (500 MHz, CDCl ₃ ): 0.63 (3H, s), 0.97 (3H, d, 6.22 Hz), 1.34 (3H, s), 2.45 (1H, dd , 7.45 Hz, 11.70 Hz), 2.60 (1H, d, 4.81 Hz), 2.87 (1H, d, 4.81 Hz), 3.55 (1H, d, 8, 36 Hz) ppm. EXAMPLE 8 Synthesis of Protected Epoxyketone 11a

A solution of 10a (18 mg, 0.061 mmol) and N- (trimethylsilyl) -imidazole (26 mg, 0.186 mmol, 27 μl) in anhydrous CH ₂ Cl ₂ (1.5 ml) was stirred at room temperature under atmosphere nitrogen for 2 hours. The mixture was chromatographed (hexane / EtOAc, 9: 1) to give compound 11a as an oil (20 mg, 89%).

 Characteristics: Rf (hexane / EtOAc, 8: 2) = 0.48.

11a spectroscopic data: ¹ H NMR (360 MHz, CDCl ₃ ): 0.09 (9H, s), 0.63 (3H, s), 0.96 (3H, d, 6.06 Hz), 1, 28 (3H, s), 2.44 (1H, dd, 7.48 Hz, 1 16.4 Hz), 2.56 (1 H, d 5, 12 Hz), 2.65 (1 H, d, 5.12 Hz), 3.17 (1H, dd, 3.29 Hz, 8.88 Hz) ppm.

EXAMPLE 9 Synthesis of (24S, 25R) - 1 alpha 24-dehydroxy-25,26-epoxy-vitamin D ₃ (26a)

To a stirred solution of phosphine oxide IV (57 mg, 0.098 mmol) in anhydrous THF (0.8 ml) at -80 ° C under an argon atmosphere was added n-BuLi (a solution 2.46 M in hexane, 0.098 mmol, 40 μl), giving a dark orange solution. The mixture was stirred again for 1 hour. Anhydrous THF (0.8 ml) was then added to the solution of compound 11a (18 mg, 0.049 mmol) dropwise. The mixture was stirred at -80 ° C for 2 hours. The solution was warmed slowly to room temperature, during this time the color turned pale yellow and eventually became almost colorless. The mixture was chromatographed (hexane / EtOAc, 12: 1) to give the crude product which was purified by HPLC (hexane / EtOAc, 14: 1) to give the pure product 25a as an oil (32 mg, 89 %).

Characteristics: Rf (hexane / EtOAc, 9: 1) = 0.78.

A solution of 25a (32 mg, 0.044 mmol) and tetrabutylammonium fluoride (0.44 mmol, 440 μl, 1 M solution in THF), in THF (2 ml), was stirred at room temperature under nitrogen, in the dark, for 3.5 hours. Tetrabutylammonium fluoride (440 μl of a 1 M 0.44 mmol solution) was added and the resulting mixture stirred for 6 hours. Ether was added, the mixture was washed with brine and the aqueous phase extracted twice with ether. The combined organic phases were dried over MgSO ₄ . After filtration and concentration, a residue was obtained which was filtered through a small column of silica gel by elution with 100 ml of 5% CH ₃ OH in CH ₂ Cl ₂ · The concentration of the filtrate gave a residue which was purified by HPLC (CH ₂ CI ₂ / CH ₃ OH 95: 5) to give the pure product 26a (16 mg, 85%). Characteristics: Rf (CH ₂ Cl ₂ / CH ₃ OH 9.5: 0.5) = 0.30.

Spectroscopic data for 26a: UV (CH ₃ OH): max = 263 nm; IR (KBr-Film): 3379 (s, br), 1643 (br), 1059 (s) 896, 800, 736 cm ^{- 1} ; ¹ H NMR (500 MHz, CDCI ₃ ): 0.54 (3H, s), 0.95 (3H, d, 6.52 Hz), 1.34 (3H, s), 2.60 (1H, d , 4.78 Hz), 2.88 (1H, bs), 5.32 (1H, bs), 6.01 (1H, d, 11.26 Hz), 6.37 (1H, d, 1 1 , 26 Hz) ppm; MS: m / z 431 (M-. + 1, 2), 394 (1), 382 (2), 355 (2), 337 (2), 285 (1), 251 (4), 227 (3) , 197 (5), 134 (100).

Example 10. Synthesis of the Diols 12a, 12b

 A mixture of 31 mg (0.28 mmol) of selenium dioxide, 83 mg, is stirred at approximately 25 ° C. under nitrogen for 0.5 hour.

 (0.93 mmol) tert-butyl hydroperoxide (90%) and 5 ml of dichloromethane. A solution of 1.85 mg (0.55 mmol) of 6 in 5 ml of dichloromethane is added over several minutes. The mixture obtained is stirred at approximately 25 ° C for 0.5 hour. Stirring is continued at -20 ° C for 22 hours. 1 ml of methyl sulfide is added, then the mixture is stirred at 25-30 ° C for 4 hours. Dichloromethane is removed with a rotary evaporator. 4 ml of acetone are added to the residue, acid is added dropwise

10% hydrochloric acid until pH 3. The mixture is stirred at 25 ° C for 1 hour, then neutralized with saturated aqueous NaHCO ₃ , extracted with ether and dried over MgSO 4. Concentrate to obtain a residue which is subjected to flash chromatography (hexane / EtOAc: 10/3) to obtain 63 mg (41%) of 12a, 12b in the form of white crystals.

Rf (hexane / EtOAc: 7/3): 0.38; [α] _D ¹⁸ + 35.82 ° (c = 1.329;

CHCl ₃ ); mp 94-108 ° C.

Spectral values of 12a, 12b: IR (KBr-film): 3,408 (F, large), 3,072 (f), 1,650, 899 cm ^-1 .

¹ H-NMR (360 MHz, CDCI3): 0.91 (d, 6.56 Hz, 3H), 0.93 (s, 3H), 1.72 (s, 3H), 4.01 (t, 1H ), 4.07 (br s, 1H), 4.83 (d, 1H), 4.92 (m, 1H) ppm.

 Example 11 Synthesis of Alcohol 12a and Epoxide 13b

 Has a solution at room temperature of 90 mg

(0.32 mmol) of 12a, 12b and 11.23 mg (0.048 mmol) of (-) - diisopropyl tartrate in 2 ml of anhydrous dichloromethane, 27 mg of pulverized and activated 4A sieve are added. The stirred mixture is kept maintained under nitrogen between -10 and -20 ° C, treated with 9.09 mg (0.032 mmol) of Ti (oi-Pr) ₄ and stirring is continued for 30 minutes at -20 ° C . The reaction mixture is then treated with a solution

tert-butyl hydroperoxide in isooctane (7.00 M;

0.224 mmol; 32 μl, dried with fresh 3A pastilles activated for 30 minutes before addition), which is added using a gas-tight syringe. The reaction mixture is stirred at approximately -20 ° C using a bath maintained at constant temperature for 23 hours. Cooled to about 0 ° C using an ice water bath 3 ml of an aqueous suspension of ferrous sulfate and tartaric acid. The mixture of the epoxidation reaction is allowed to warm to about 0 ° C., then it is poured slowly into a beaker containing the stirred cooled ferrous sulphate solution (external cooling is not essential during or after this addition). The mixture is stirred in two phases for about

10 minutes, then transfer to a separatory funnel. The phases are separated and the aqueous phase is extracted with two 6 ml portions of ether. The combined organic layers are treated with 3 ml of a previously cooled (0 ° C) solution of 30% NaOH in saturated salt water. The two-phase mixture is stirred vigorously for 1 hour at 0 ° C. After transfer to a separating funnel and dilution with 3 ml of water, the phases are separated and the aqueous layer is extracted with two 15 ml portions of ether. The combined organic layers are washed with saturated aqueous NaCl and dried over MgSO ₄ . Filtered and concentrated to obtain a residue which is separated by HPLC (hexane / EtOAc: 7/4) to obtain 32 mg of optically pure 13b in the form of white crystals, 4 mg of a

13b stereoisomer (characterized by ¹ H-NMR) and 55 mg of crude 12a in the form of white crystals still containing the 24- (R) isomer (according to ¹ H-NMR 1500 MHz). The crude product 12a is subjected to a second Sharpless kinetic splitting to obtain 33 mg of optically pure 12a.

For 12a: Rf (hexane / EtOAc: 1/1): 0.61; [α] _D ¹⁸ + 32.58º (c = 1.016; CHCl ₃ ); mp 121.5-123.5 ° C.

Spectral values: IR (KBr-film): 3,374 (F, large), 3,073 (f), 1,651 (f), 899 cm ^-1 .

¹ H-NMR (500 MHz, CDCI ₃ ): 0.91 (d, 6.56 Hz, 3H), 0.93 (s, 3H), 1.72 (S, 3H), 4.02 (t, 1H), 4.07 (broad s, 1H), 4.83 (t, 1H), 4.92 (t, 1H) ppm.

MS: m / z 280 (M ⁺ : 0.04), 262 (10.8), 247 (5.8), 229 (5.7), 190 (6.3), 163 (15.9), 135 (43.2).

For 13b: Rf (hexane / EtOAc: 1/1): 0.44; [α] _D ²⁰ + 40.89º (c = 1.010; CHCl ₃ ); mp 97-98 ° C.

Theoretical analysis for C ₁₈ H ₃₂ O ₃ : C = 72.97; H = 10.81; found: C = 72.83; H = 110.85.

Spectral values: IR (KBr-film): 3,440 (F, large), 1,267, 942, 756 cm ^{- 1} .

¹ H-NMR (500 MHz, CHCl ₃ ): 0.93 (s, 3H), 1.34 (s, 3H), 2.60 (d, 4.78 Hz, 1H), 2.89 (d, 4.78 Hz, 1H), 3.61 (m, 1H), 4.07 (broad s, 1H) ppm.

 MS: m / z 278 (0.7), 263 (1.3), 260 (0.7), 245 (0.7), 193 (2), 177 (4.7), 161 (7.3 ), 135 (17.4), 111 (100).

Example 12 Synthesis of Epoxyketone 14b

 A mixture of 25 mg (0.084 mmol) of 13b, 63 mg (0.168 mmol) of pyridinium dichromate (OCP) and 2.5 ml of dichloromethane is stirred at 0 ° C. under nitrogen for 4 hours. 16 mg (0.043 mmol) of DCP are added, then the reaction mixture is allowed to return to room temperature and stirred for 2 hours. The mixture is subjected directly to flash chromatography (hexane / EtOAc: 6/4) to obtain 20 mg of 14b in the form of white crystals (80%). Rf (hexane / EtOAc: 6/4): 0.33; mp 84-85 ° C.

Spectral values of 14b: IR (KBr-film): 3,446 (F, large), 1,711 (F), 1,266, 942, 814 cm ^-1 .

¹ H-NMR (360 MHz, CHCl ₃ ): 0.64 (s, 3H), 0.97 (d, 5.53 Hz, 3H), 1.34 (8.3H), 2.45 (dd, 11.64 Hz, 7.48 Hz, 1H), 2.60 (d, 4.75 Hz, 1H), 2.89 (d, 4.75 Hz, 1H) 3.61 (d, 1H).

Example 13. Synthesis of Epoxyketone 15b

 A solution of 20 mg (0.068 mmol) of 14b and 19 mg is stirred under nitrogen at ordinary temperature for 1 hour.

(0.136 mmol; 20 μl) of N- (trimethylβilyl) imidazole in 2 ml of CH ₂ Cl ₂ . The mixture is then subjected directly to a

flash chromatography (hexane / EtOAc: 9/1) to obtain 22 mg of 15b in the form of an oil (88%).

Rf (hexane / EtOAc: 8/2): 0.49.

Spectral values of 15b: ¹ H-NMR (500 MHz, CHCl ₃ ): 0.09 (s, 9H), 0.63 (s, 3H), 0.96 (d, 5.89 Hz, 3H); 1, 28 (s, 3H), 2, 45 (dd,

 11, 61 Hz, 7.49 Hz, 1H), 2.56 (d, 5, 12 Hz, 1H), 2.67 (d, 5, 12 Hz, 1H), 3.22 (dd, 8, 56 Hz, 3.62 Hz, 1H) ppm.

Example 14. Synthesis of (24R, 25S) -lC_, 24-dihydroxy-25,26-eρoxy- vitamin D ₃ (28b)

 To a stirred solution of 54 mg (0.093 mmol) of phosphine oxide IV in 0.6 ml of anhydrous THF souβ nitrogen at -80 ° C, n-BuLi (2.5 M solution in hexane; 0.093 mmol; 37 μl) to obtain a dark orange solution. The mixture is stirred under these conditions for 1 hour. 17 mg (0.046 mmol) of 15b in 0.8 ml of anhydrous THF are added slowly to the solution. The mixture obtained is stirred at -80 ° C for 2 hours. The solution is allowed to slowly return to room temperature, while it turns pale yellow and finally becomes almost colorless, the mixture is directly subjected to flash chromatography (hexane / EtOAc: 12/1) to obtain 27b crude as we still purify by HPLC

 (hexane / EtOAc: 18/1) to obtain 28 mg (82%) of pure 27b in the form of an oil.

 Rf (hexane / EtOAc: 9/1): 0.74.

A solution of 28 mg (0.038 mmol) of the latter compound and of (n-Bu) ^ NF (1 M solution in THF; 0.75 mmol; 760 μl) in 1 to 5 ml of THF is protected from light. and stirred at room temperature under nitrogen for 9 hours. The mixture is filtered directly through a short column of silica gel, eluting with 100 ml of 10% CH ₃ OH in CH ₂ Cl ₂ . By concentration, a residue is obtained which is separated by HPLC (CH ₂ Cl ₂ / CH ₃ OH: 95/5) to obtain 12 mg of pure 28b, in the form of a white solid (73%).

Rf (CH ₂ Cl ₂ / CH ₃ OH: 9.5 / 0.5): 0.29; [α] _D ¹⁸ = 32.37º (c = 1.035, CHCl ₃ ).

Spectral values of 28b: UV (CH ₃ OH): λ _maχ = 262 nm.

1H-NMR (500 MHz, CHCl ₃ ): 0.55 (s, 3H), 0.94 (d, 6.50 Hz, 3H), 1.34 (s, 3H), 2.31 Cad, 13, 43 Hz, 6.63 Hz, 1H), 2.60 (d, 4.77 Hz, 1H), 2.89 (d, 4.77 Hz, 1H), 3.61 (m, 1H), 4, 22 (broad s, 1H), 4.43 (broad s, 1H), 5.00 (broad s, 1H), 5.32 (t, 1H), 6.02 (d, 11.27 Hz, 1H) , 6.38 (d, 11.27 Hz, 1H) ppm.

ACEMENT MS: m / z 394 (2), 336 (2), 251 (3).

 Example 15. Synthesis of alkenols 16 and 16 '

To a solution of 0.47 g (1.28 mmol) of 16 in 5.0 ml of tetrahydrofuran at -78 ° C under argon, 6.0 ml of a 1.25 M solution of chloride is added dropwise of isopentenylmagnesium (7.5 mmol; 6 equivalents), then 6.4 ml of a 0.1 M solution of dilithium-copper (II) tetrachloride (0.64 mmol; 0.5 equivalent) in tetrahydrofuran. The reaction mixture is allowed to return to room temperature, stirred for a further 16 hours, then poured into 50 ml of a saturated solution of ammonium chloride. The aqueous layer is extracted several times with diethyl ether, then the combined ether layers are washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue is chromatographed on silica gel and on a 10 μm silica HPLC column with a mixture of isooctane / ethyl acetate (9/1) as eluent, in both cases to obtain the isomeric alkenols 16 and 16 '(0.31 g; 92%) in the form of a mixture (3/7 according to the ¹ H-NMR spectrum values). Rf (isooctane / ethyl acetate: 9/1): 0.20.

Spectral values of 16: IR (KBr-film): 3 403 (F), 2 936 (F),

2 867 (F), 1 641, 1 445, 1 376, 1 268, 1 234, 1 165, 1 118, 1 065, 1 035, 990, 942, 912, 886, 858, 822, 787, 725, 698 and 668 cm ^-1 .

1H-NMR (CHCl ₃ : 360 MHz): 5.09 (1H, t, 7.1 Hz, LR 1.4 Hz), 4.07 (1H, broad s), 2.01 (2H, m), 1.83 (4H, m), 1.68 (3H, wide s), 1.60 (3H, wide s), 0.93 (3H, s) and 0.91 (3H, d, 6.5 Hz );

SM: m / z & 264 (M ⁺ : 2), 249 (3), 246 (3), 231 (4), 179 (7), 161 (12), 151 (26), 133 (22), 125 (11), 111 (28), 95 (21), 84 (43), 69 (46), 55 (44) and 49 (100).

Spectral values of 16 '(for a 3/7 mixture of 16/16'):

IR (KBr-film): 3,420 (F), 3,081 (F), 2,868 (F), 1,656, 1,638, 1,546, 1,453, 1,413, 1,378, 1,361, 1,268, 1 234, 1,165, 1,066, 1,032, 991, 959, 941, 908, 885, 858, 820, 785, 725 and 692 cm ^-1 .

1H-NMR (CHCl ₃ , 360 MHz): 5.79 (1H, dd, 17.8, 10.4 Hz), 4.89 (1H, m), 4.85 (1H, m), 4.05 (1H, s broad), 0.98 (3H, s), 0.97 (3H, s), 0.93 (3H, s) and 0.91 (3H, d, 6.5 Hz). SM: m / z to 264 (M ⁺ : 2), 249 (4), 246 (4), 231 (5), 179 (9), 161 (15), 151 (34), 133 (27), 125 (18), 111 (60), 95 (34), 81 (39), 69 (74), 55 (82) and 43 (100).

 Example 16. Synthesis of the Epoxy Alcohols 17a, 17b and 17'a, 17'b

 To a solution of 0.29 g (1.1 mmol) of a 3/7 mixture of 16 and 16 'in 13 ml of anhydrous dichloromethane, 0.43 mg (2.1 mmol) of acid m is added. -choroperbenzoic acid (AmCPB) and the solution is stirred for 3 hours at room temperature. 0.5 g of potassium carbonate is added, stirring is continued for

 15 minutes, the reaction mixture is filtered and the remaining solid is washed with dichloromethane and filtered. The combined filtrates are concentrated under reduced pressure and the residue is purified on silica gel and on a 10 μm column of HPLC of silica with a 3/2 mixture of isooctane / ethyl acetate as eluent, in both cases, to obtain 0.21 g (68%) of 17a, 17b and 17'a, 17'b in the form of a mixture.

 Rf (isooctane / ethyl acetate: 8/2): 0.18.

 Chromatography of this mixture on a reverse phase HPLC column made up of 10 μm RSilC18HL with an 8/2 mixture of methanol / water as eluent provides 0.131 g of the diastereoisomers 17'a and 17'b. Additional purification of the remaining material on a 10 μl silica HPLC column with an 8/2 mixture of iβooctane / ethyl acetate provides 0.025 g of the diastereomers 17a and 17b.

Rf (iaooctane / acetone: 9/1): 17a, 17b: 0.19; 17'a, 17'b: 0.23. Spectral values of 17a, 17b: IR (KBr-film): 3 465 (F), 2 933 (F), 1 455, 1 378, 1 327, 1 266, 1 251, 1 180, 1 166, 1 118, 1 066, 1035, 992, 943, 899, 859, 792, 737, 701 and 680 cm ^-1 .

1H-NMR (CHCl ₃ , 360 MHz): 4.07 (1H, broad s), 2.68 (1H, t, 6.0 Hz), 1.99 (1H, dm, 11.9 Hz), 1 , 93-1.75 (3H, m), 1.30 (3H, s), 1.26 (3H, s), 0.93 (3H, s) and 0.91 (3H, d, 6.5 Hz).

SM: m / z at 280 (M ⁺ : 1), 265 (3), 262 (5), 247 (3), 229 (4), 219 (4), 179 (5), 161 (10), 151 (20), 133 (20), 125 (16), 111 (60), 95 (32), 81 (41), 67 (38), 55 (72) and 43 (100).

Spectral values of 17'a, 17'b: IR (KBr-film): 3,454 (F), 2,930 (F), 2,870 (F), 1,472, 1,403, 1,375, 1,362, 1,267, 1,167, 1,067, 1,033, 1,018, 992, 942, 913, 886, 859, 835, 784 , 722, 688, 668 and 658 cm ^{- 1} .

¹ H-NMR (CHCl ₃ , 360 MHz): 4.06 (1H, broad s), 2.74 (1H, dd, 4.0, 3.0 Hz), 2.62 (2H, m), 2 , 00 (1H, dm, 13.2 Hz), 1.92 (1H, m), 1.81

(2H, m), 0.99 + 0.97 (3H, 2 × d, 6.2 Hz), 0.96 (3H, s), (0.89 + 0.87 (3H, 2 × s) and 0.83 + 0.81 (3H, 2 × s).

 SM: m / z to 262 (1), 247 (2), 219 (1), 203 (1), 191 (2), 179 (4), 162 (6), 151 (8), 135 (15) , 125 (19), 111 (66), 95 (34), 81 (37), 69 (45) and 55 (100).

 Example 17. Synthesis of Epoxyketones 18a, 18b

 To a solution of 0.021 g (0.075 mmol) of 17a, 17b in 2.0 ml of anhydrous dichloromethane is added 0.079 g (0.21 mmol; 2.8 equivalents) of pyridinium dichromate (DCP) and a catalytic amount of pyridinium p-toluenesulfonate (PTSP) and the suspension is stirred for 4.5 hours at room temperature under argon. 3 ml of diethyl ether are added, stirring is continued for 5 minutes, the reaction mixture is filtered through a bed of Celite / silica gel using ether and the precipitated chromium salts are washed several times with ether and filtered. The combined filtrates are concentrated under reduced pressure and the residue is purified by HPLC on a 10 μm silica column with a 9/1 mixture of isooctane / acetone as eluent. 0.017 g is thus obtained (80% of the mixture of diastereoisomers 18a and 18b in the form of an oil).

 Rf (isooctane / acetone: 9/1): 0.25.

Spectral values of 18a, 18b: IR (KBr-film): 2 958 (F), 2 875 (F), 1 714 (F), 1 462, 1 378, 1 324, 1 308, 1 242, 1 223, 1,191, 1,172, 1,120, 1,056, 943, 900, 867, 837, 794 and 680 cm ^-1 .

1H-NMR (CHCl ₃ , 360 MHz): 2.67 (1H, t, 6.0 Hz), 2.45 (1H, ddd, 11.5, 7.2, 2.9 Hz), 2.32 -2.16 (2H, m), 2.11 (1H, dm, 13.2 Hz), 2.05-1.82 (3H, m), 1.73 (1H, m), 1.30 ( 3H, s), 1.26 (3H, s), 0.97 (3H, d, 6.0 Hz) and 0.64 (3H, s).

SM: m / z to 278 (M ⁺ : 2), 260 (3), 235 (3), 205 (6), 192 (6), 177 (8), 149 (24), 135 (10) 124 ( 20), 111 (40), 96 (36), 81 (48), 67 (36), 55 (72) and 41 (100).

Example 18. Synthesis of 24 (S) -1-α-hydroxy-24,25-epoxyvitamin D ₃

(30a) and 24 (R) -24.25-epoxy-1-α-OH-vitamin D ₃ (30b) A solution cooled to -70ºC of 0 is placed under an atmosphere of 1.1 bar of argon 0.06 g (0.103 mmol; 2.05 equivalents) of IV in 1.0 ml of anhydrous tetrahydrofuran and 0.039 ml of a 2.5 M solution of n-butyllithiura in n-hexane (0.096 mmol) is added. The dark red solution obtained is stirred for 30 minutes. 0.014 g (0.05 mmol) of the ketones 18a, 18b dissolved in 0.5 ml of anhydrous tetrahydrofuran are added dropwise. The mixture is stirred at -70 ° C for 1.5 hours, then allowed to return to room temperature over a period of 2.5 hours. 2 to 3 drops of water are added to the still red solution and most of the solvents are removed under a stream of argon. 2.0 ml of a saturated sodium bicarbonate solution are added, which is extracted several times with 2.0 ml of diethyl ether. The combined extracts are filtered through a bed of Kieselgel 60 from Merck and the solvent is removed under reduced pressure. The residue is quickly chromatographed on a 10 μm HPLC silica column with an 85/15 mixture of n-hexane / ethyl acetate as eluent. The oil obtained is immediately taken up (mixture of 29a and 29b) in 0.4 ml of anhydrous tetrahydrofuran, 0.2 ml of a 1 M solution of 1 M tetrabutylammonium fluoride (FTBA) in tetrahydrofuran is added and the mixture is stirred the solution for 19 hours at room temperature under argon away from light. The solvent is removed under a stream of argon and

chromatograph the residue on Merck Kieselgel 60 using a 9/1 mixture of dichloromethane / methanol as eluent. Additional purification by HPLC (10 μm silica; 95/5 mixture of

dichloromethane / methanol) provides 0.018 g (86%) of the mixture of the diaβtereoisomers 30a and 30b in the form of a glassy material.

Rf (dichloromethane / methanol: 9/1): 0.36.

Spectral value of 30a, 30b:

UV (MeOH) λ _max = 263 nm.

IR (KBr-film): 3 409 (F), 2 951 (F), 2 298 (F), 1 647, 1447, 1 379, 1266, 1056, 958, 896, 800, 738 and 703 cm ^-1 . ¹ H-NMR (CDCl ₃ , 350 MHz): 6.37 (1H, d, 11.2 Hz), 6.01 (1H, d,

 11.2 Hz), 5.32 (1H, m), 5.00 (1H, m), 4.43 (1H, m), 4.22 (1H, m),

2.82 (1H, dd, 11.8, 3.7 Hz), 2.68 (1H, t, 6.0 Hz), 2.59 (1H, dd,

13.2, 3.5 Hz), 2.31 (1H, dd, 13.2, 6.5 Hz), 2.05-1.85 (5H, m), 1.31

(3H, s), 1.26 (3H, s), 0.94 (3H, d, 6.3 Hz) and 0.55 (3H, s).

SM: m / zi 414 (M ⁺ : 7), 396 (45), 378 (34), 269 (5), 251 (9), 195

(6), 181 (5), 171 (7), 169 (6), 161 (8), 159 (9), 157 (12), 155 (16),

152 (19), 134 (61), 105 (28), 91 (27), 81 (24), 71 (22), 55 (41) and

43 (100).

 EXAMPLE 19 Synthesis of the Epoxyketones 18'a, 18'b

 To a solution of 0.096 g (0.34 mmol) of 17'a, 17'b in 8.0 ml of anhydrous dichloromethane, 0.36 g (0.95 mmol;

2.8 equivalents) of pyridinium dichromate (DCP) and a catalytic amount of pyridinium p-toluenesulfonate (PTSP) and the suspension is stirred for 4.5 hours at room temperature under argon. 10 ml of diethyl ether are added, stirring is continued for 5 minutes, the reaction mixture is filtered through a bed of Celite / silica gel using ether and washed several times with ether. precipitated chromium salts and filtered. The combined filtrates are concentrated under reduced pressure and the residue is purified by HPLC on a 10 μm silica column with a 95/5 mixture of isooctane / acetone as eluent. 0.070 g (74%) of a mixture of the diastereoisomers 18'a and 18'b is obtained in the form of an oil.

Rf (isooctane / acetone: 95/5): 0.16.

Spectral value of 18'a, 18'b:

IR (KBr-film): Z 960 (F), 2 348 (F), 2 282 (F), 1 714 (F), 1 470,

1,379, 1,308, 1,246, 1,225, 1,057, 943, 913, 840 and 733 cm ^-1 .

1H-NMR (CHCl ₃ , 360 MHz): 2.73 (1H, t, 3.5 Hz), 2.61 (2H, m), 2.44 (1H, dd, 11.7, 7.5 Hz ), 2.31-2.16 (2H, m), 2.13 (1H, dm, 13.2 Hz), 2.04-1.81 (3H, m), 1.71 (1H, m) , 1.30 (2H, m), 1.09 (1H, ddd, 14.1, 10.8, 8.3 Hz), 1.04 + 1.02 (3H, 2 × d, 6.7 Hz ), 0.87 + 0.85 (3H, 2 × s), 0.84 + 0.82 (3H, 2 × s) and 0.66 + 0.65 (3H, 2 × s).

SM: m / zi 278 (M *: 1), 248 (1), 193 (12), 178 (8), 163 (7), 149 (14), 135 (14), 124 (22), 111 ( 36), 95 (30), 81 (43), 69 (36) and 55 (100).

Example 20 Synthesis of 24 (S) -1α-hydroxy-24,25-epoxy-25,25-dinor-23,23-dimethylvitamin D ₃ (30'a) and 24 (R) -24.25 - epoxy-25,25-dinor-23,23-dimethyl-1α-OH-vitamin D ₃ (30'b) A solution of 0.085 g (0.146 mmol; 2) is placed under an atmosphere of 1.1 bar of argon , 03 equivalents) of IV in 1.4 ml of anhydrous tetrahydrofuran and 0.056 ml of a solution of 2.5 M n-butyllithium in n-hexane (0.14 mmol) is added. The dark red solution obtained is stirred for 30 minutes. 0.02 g (0.072 mmol) of the ketones 18'a, 18'b dissolved in 0.8 ml of anhydrous tetrahydrofuran are added dropwise. The mixture is stirred at -70 ° C for 1.5 hours and then allowed to return to room temperature over a period of 2.5 hours. 2 to 3 drops of water are added to the still red solution and most of the solvents are removed under a stream of argon. 2.0 ml of a saturated sodium bicarbonate solution are added and then extracted several times with 2.0 ml of diethyl ether. The combined extracts 1 are filtered through a bed of Kieselgel 60 from Merck and the solvent is removed under reduced pressure. The residue is quickly chromatographed on a 10 μm HPLC column with an 85/15 mixture of n-hexane / ethyl acetate as eluent. The oil obtained is immediately taken up (mixture of 29'a and 29 'b) in 0.5 ml of anhydrous tetrahydrofuran, 0.025 ml of a 1 M solution of tetrabutylammonium fluoride (FTBA) in tetrahydrofuran is added and the mixture is stirred the solution for 30 hours at room temperature under argon away from light. The solvent is removed under a stream of argon and the residue is chromatographed on Merck Kieselgel 60 with a 9/1 mixture of

dichloromethane / methanol. Additional purification by HPLC (10 μm silica; 95/5 mixture of dichloromethane / methanol) provides 0.023 g (77%) of a mixture of the diastereoisomers 30'a and 30'b in the form of a vitreous material.

Rf (dichloromethane / methanol: 9/1) t 0.41.

Spectral value of 30'a, 30'b:

UV (MeOH) λ _max = 263 nm.

IR (KBr-film): 3 404 (F), 2 950 (F), 2250, 1642, 1444, 1378, 1,054, 958, 910, 833, 800 and 735 cm ^{- 1} .

¹ H-NMR (CDCl ₃ , 360 MHz): 6.37 (1H, d, 11.2 Hz), 6.02 (1H, d,

 11.2 Hz), 5.32 (1H, wide s), 4.99 (1H, wide s), 4.42 (1H, m), 4.22 (1H, m), 2.81 (1H, dd, 11.8, 3.8 Hz), 2.75 (1H, dd, 4.0, 3.0 Hz), 2.61 (3H, m), 2.31 (1H, dd, 13.4 , 6.4 Hz), 2.05-1.87 (5H, m), 1.07 (1H, ddd, 14.1, 11.9, 8.3 Hz), (1.02 + 1.00 <3H, 2 xd, 6.5 Hz), 0.89 + 0.87 (3H, 2 xs), 0.83 + 0.81 (3H, 2 xs) and 0.58 + 0.57 (3H,

2 × s).

SM: m / z 1,414 (M ⁺ : 7), 396 (64), 378 (36), 367 (6), 352 (5), 285 (6), 269 (7), 251 (10) 209 ( 10), 195 (9), 152 (27), 134 (83), 105

(38), 95 (27), 91 (34), 81 (31), 69 (51) and 55 (100).

 Example 21. Synthesis of Ketone 20

 From tosylate le, the reaction with the lithian derivative obtained from the acetal of 3-butyne-2-one provides acetal 19 according to the procedure of Uskokovic described for an analogous product in ref. 32.

IR (KBr): 3,475, 2,935, 2,867, 2,207, 1,675 cm ^-1 .

 The hydrolysis is carried out in aqueous dioxane in the presence of sulfuric acid. Ketone 20 presents the values

spectroscopic:

IR (KBr-film): 3,475, 2,935, 2,867, 2,207, 1,675 cm ^-1 .

¹ H-NMR (360 MHz, CHCl ₃ ): 4.09 (m, 1H), 2.41 (1H, dd, 17.2, 3.6 Hz),

2.33 (3H, S), 2.21 (1H, dd, 17.2, 7.6 Hz), 1.05 (3H, d, 6.6 Hz), 0.93

(3H, s) ppm.

Example 22. Synthesis of epoxides 21a, 21b

 The mixture is stirred at 60 ° C. under nitrogen for 5 minutes.

131 mg (0.642 mmol) trimethylsulfonium iodide, 54 mg

 (0.964 mmol) of potassium hydroxide powder and 1 ml

acetonitrile. A solution of 50 mg of 20 (0.160 mmol) in 1 ml of acetonitrile is added, which produces an orange color. The mixture obtained is stirred for 1 hour and 40 minutes. The color turns yellow. The mixture is filtered directly through a short column of silica gel, eluting with 220 ml of EtOAc & 50% in hexane.

By concentration, a residue is obtained which is separated by HPLC (hexane / EtOAc: 8/2) to obtain 13 mg (30%) of 21a, 21b in the form of an oil.

 Rf (hexane / EtOAc: 8/2): 0.31.

Spectral values for 21a, 21b: IR (KBr-film): 3,456 (F, large), 3,047 (f), 2,240 (f), 1,271 (F), 943 (F), 760 cm ^-1 .

1H-NMR (360 MHz, CHCl ₃ ): 0.93 (s, 3H), 1.04 (d, 6.58 Hz, 3H), 1.54 (s, 3H), 2.02 (m, 1H ), 2.25 (m, 1H), 2.72 (d, 5.55 Hz, 1H), 2.97 (d, 5.55 Hz, 1H), 4.08 (broad s, 1H) ppm.

 MS: m / z 261 (1.7), 243 (2.1), 163 (10.3), 95 (40.2), 81 (60.3). Example 23 Synthesis of Epoxyketones 22a, 22b

 A 25 mg mixture is stirred under nitrogen for 4 hours

(0.091 mmol) of 21a, 21b, 103 mg (0.274 mmol) of DCP and 2 ml of dichloromethane. The mixture is filtered directly through a short column of silica gel, eluting with 200 ml of 25% EtOAc in hexane. By concentration, a residue is obtained which is purified by HPLC (hexane / EtOAc: 8/2) to obtain 19 mg (76%) of 22a, 22b in the form of an oil.

 Rf (hexane / EtOAc: 8/2): 0.33.

Spectral values of 22a, 22b: IR (KBr-film): 2 239 (f), 1 712 (F), 1271, 857, 763 cm ^-1 .

1H-NMR (360 MHz, CDCI ₃ ): 0.63 (s, 3H), 1.09 (d, 6.20 Hz, 3H), 1.54 (s, 3H), 2.47 (dd, 11 , 61 Hz, 7.51 Hz, 1H), 2.73 (d, 5.55 Hz, 1H); 2.97 (d, 5.55 Hz, 1H) ppm.

Example 24 Synthesis of Vitamin D Derivatives ₃ 32a, 32b

 To a stirred solution of 77 mg (0.132 mmol) of phosphine oxide IV in 1 ml of anhydrous THF under nitrogen at -80 ° C, 53 μl of a 2.5 M solution of n-BuLi in a mixture are added of hexanes, which provides a dark orange solution. The mixture is stirred under these conditions for 1 hour. The solution 18 mg (0.066 mmol) of 22a, 22b in 0.8 ml of anhydrous THF is added slowly dropwise to the solution. The mixture obtained is stirred at -80 ° C for 2 hours. The solution is allowed to slowly return to room temperature while it turns pale yellow and finally becomes almost colorless. The mixture is subjected directly to flash chromatography (hexane / EtOAc: 9/1) to obtain a crude product which is purified by HPLC (hexane / EtOAc: 18/1) to obtain 37 mg (88%) of 31a, 31b completely pure

REPLACEMENT SHEET in the form of an oil.

 Rf (hexane / EtOAc: 9/1): 0.64.

Protect from light a solution of 37 mg (0.058 mmol) of 31a, 31b and 700 μl of a 1 M solution of (n-Bu) ₄ NF 1 M in THF (0.70 mmol) in 1.5 ml of THF, then stirred under nitrogen for

8 hours. The mixture is filtered directly on a short column of silica gel, eluting with 100 ml of 8% CH ₃ OH in CH ₂ Cl ₂ . By concentration, a residue is obtained which is separated by HPLC (CH ₂ Cl ₂ / CH ₃ OH: 96/4) to obtain 19 mg (80%) of pure 20 in the form of a white solid.

Rf (CH ₂ Cl ₂ / CH ₃ OH: 9.5 / 0.5): 0.38

Spectral values for 32a, 32b: UV (CH3OH): λ _max = 262 nm.

 IR (KBr-film): 3,304 (F, large), 2,239 (f), 1,647 (wide), 1,271,

1054 (F), 911, 863, 800, 737 cm ^-1 .

1H-NMR (360 MHz, CHCl ₃ ): 0.54 (s, 3H), 1.06 (d, 6.51 Hz, 3H), 1.54 (s, 3H), 2.28 (m, 2H ), 2.59 (m, 1H), 2.73 (d, 5.56 Hz, 1H), 2.83 (m, 1H), 2.97 (d, 5.56 Hz, 1H), 4, 22 (m, 1H), 4.42 (m, 1H), 4, .9 (wide s, 1H), 5.32 (wide s, 1H), 6.01 (d, 11.25 Hz, 1H) , 6.37 (d, 11.25 Hz, 1H) ppm.

MS: m / z 410 (M ⁺ : 16), 392 (28), 374 (25), 359 (3), 315 (3), 297 (4), 279 (3), 134 (100).

Example 25. Synthesis of Diol 1b

 The diol la is oxidized with pyridinium dichromate (DCP) in the presence of pyridinium p-toluenesulfonate in dichloromethane. Oxidation is not selective and a mixture is obtained

hydroxyketone, ketoaldehyde, hydroxyaldehyde 2a. After purification of the latter (Rf: 0.22; ethyl acetate / hexane: 1/1) on silica gel, it is treated with a catalytic amount of diazabicyclo-undecene in dichloromethane. After 3 hours, treat with ether. The ethereal solution is washed with 2 ml of 5% hydrochloric acid. After drying over Na ₂ SO ₄ , filtration and concentration, a mixture of aldehydes 2a and 2b is obtained.

(respectively 36/64 according to ¹ H-NMR). Rf (ether / hexane: 1/1): 0.28. 101 mg (0.48 mmol) of this mixture are dissolved in 10 ml of methanol and treated at 0 ° C. with 90 mg (2.38 mmol) of borohydride. sodium. After 30 minutes, the mixture is concentrated in vacuo and ice and 20 ml of ether are added. After washing the organic phase with 1 ml of 5% hydrochloric acid and water, it is dried (Na ₂ SO ₄ ) and the residue obtained is purified by concentration in vacuo

chromatography on silica gel (benzene / hexane / ether: 3/2/5). 62 mg (0.293 mmol) of the isomer 1b are thus obtained having an Rf of 0.18 alongside the isomer la (Rf: 0.16).

Spectral values of 2a: ¹ H-NMR (500 MHz, CHCl ₃ ): 9.57 (1H, d, 3.18 Hz), 4.11 (1H, m), 1.10 (3H, d, 6, 83 Hz) and 0.98 (3H, s) ppm.

Spectral values of 2b: 9.53 (1H, d, 4.96 Hz), 4.09 (1H, m), 1.02 (3H, d, 6.82 Hz) and 0.95 (3H, s) ppm.

 Spectral values of lb: 4.08 (1H, m), 3.72 (1H, dd, 3.5, 10.7 Hz), 3.45 (1H, dd, 6.9, 10.6 Hz), 0.955 (3H, s), 0.954 (3H, d,

6.6 Hz) ppm.

EXAMPLE 26 Synthesis of hydroxyaldehyde 2a from tosylate 1c.

A solution of tosylate J] _c (100 mg, 0.27 mmol) and collidine (66 mg, 0.55 mmol) in dimethylsulfoxide (3 ml) is stirred at 150 ° C for 30 minutes under argon. After cooling, water is added. After extraction with CH ₂ Cl ₂ . the organic phase is washed (NaCl) and dried. After concentration, we immediately proceed to the next step. According to the NMR analysis, a mixture of 2a and 2b is obtained in propositions 3: 1.

EXEM PLE 26: Experimental models for biological evaluation

1) Study of the differentiation of leukemic cells

Human leukemia cells HL-60 (promyelocytic line) are cultured in T-25 flasks at a density of 1.2 × 10 cells per ml of RPMI 1640 medium (containing 10% of heat-inactivated fetal calf serum and antibiotics ) and in the presence of increasing concentrations of 1 alpha, 25- (OH) ₂ D ₃ OR analogs. The cells are then cultured for 4 days at 37 ° C. under an atmosphere of 5% CO ₂ in air. Cell maturation, namely the differentiation of promyelocytic cells into macrophages, is evaluated by the NBT reduction test (Tetrazolium Nitro Blue salt), according to the method of Ostrem et al [23]. The percentage of cells containing formazan granules (black) is determined by counting the cells using a hematocytometer.

2) Study of the differentiation of human epidermal cells

The pharmacological property of cell differentiation is also studied on human epidermal cells or keratinocytes, in primary culture. Keratinocytes are isolated from skin fragments (biopsies, surgical resection), according to the method described by Matsumoto et al [24]. The skin fragments are incubated overnight at 4 ° C. in the absence of a buffered saline solution (150 mM PBS, pH 7.4), containing 100 U of dispase per ml. The epidermis is then separated from the dermis, then treated for 10 minutes in the presence of a 0.25 ° trypsin solution &, 0.02% EDTA, at room temperature. The reaction is stopped by adding PBS containing 10% calf serum. The cells are then washed twice by centrifugation, resuspended in the complete culture medium, then cultured at 37 ° C. and at 5 °. as CO ₂ in air, in T-25 bottles. The complete culture medium is the modified MCDB 1 53 medium (Gibco) without serum and containing pituitary extract of beef and epidermal growth factor [24]. After 24 hours, the epiderm ic cells adhere to the support and will multiply gradually. For the study of the biological activity of the compounds, the cells obtained after the second passage are cultured in multiwell plates

(24 or 96 wells) at a cell density of 5 to 8 × 10 ⁴ cells / cm. After

24 hours, increasing concentrations of 1 alpha, 25- (OH) ₂ D ₃ and the like are added to the culture medium. After different incubation times, cell growth and differentiation are determined using the following evaluation parameters:

 (a) cell viability [MTT test or tetrasolium salt according to the Bio-Rad protocol; LDH measurement];

 (b) total protein [BCA method or Pierce bicinchoninic acid];

 (c) cell growth [incorporation of tritiated thymidine];

 (d) epidermal differentiation [differential staining of cytokeratins with Rhodanile Blue, cytochemical detection of keratin 67 k, filaggrin and involucrine using specific monoclonal antibodies (Biosoft; Biomedical Technologies)].

3) Effect on the proliferation of lymphocyte cells

 This test determines the capacity of a compound, in this case a vitamin D analog, to inhibit the multiplication (proliferation) of lymphocyte cells, previously stimulated by phytohemagglutinin.

The cells of the white line are isolated by centrifugation of heparinized human blood on Ficoll-Paque (buf fy coat technique). The buffy coat cells are treated with phytohemagglutinism, then cultured in the presence of increasing concentrations of compounds and tritiated thymidine, according to a protocol described above [25]. At the end of the incubation, the radioactivity associated with the cells is measured. Cell proliferation is defined as the ratio between the radioactivity associated with cells in the presence of compounds and that of control cells, expressed in percent. 4) Study of the antiproliferative effect on human tumor cells Different tumor cell lines are used to determine the anti-tumor properties of vitamin D analogs. These are in particular human cell lines originating from

adenocarcinoma of the breast (MCF-7, T-47D), colon (CX I), lung (LX 1) or melanoma (MM-96).

 During the test, cells are grown in 96-well multiwell plates. The initial cell density is from 2 to 5,000 cells per well depending on the line envisaged, in order to keep the cells in log phase of growth throughout the duration of the experiment. After 24 hours, the cells are incubated in the presence of increasing concentrations of vitamin D and its analogs, for different periods of time. At the end of each incubation, the protein concentration is determined (Pierce BCA method), the incorporation of tritiated thymidine and the cell viability (MTT and LDH test). Its various parameters make it possible to evaluate cell growth and the cytotoxic effect of the compounds. The anti-tumor activity is expressed as a percentage of growth inhibition relative to the control cells. 5) Calcifying effect in rickets chicken

 The rachitic chicken model makes it possible to evaluate the pharmacoiogical effect of vitamin D on the calcium-calcium metabolism, and in particular in the intestine (calcium absorption) and bone tissue (mineralization). It is a question of studying in this model the calcifying effect of vitamin D [26].

Rachitic chickens are obtained by raising chicks, from their birth, in the absence of light and under a diet low in calcium. After three weeks, the animals are treated for 10 days with vitamin D or its analogs, at the rate of a daily intramuscular injection. At the end of the treatment, the animals are sacrificed; serum, intestine and bone tissue are then removed. The serum and bone calcium content is measured by atomic absorption; Serum posterocalcin and the intestinal protein calbindin-28k, two vitamin D-dependent proteins, are determined by an RIA radioimmunoassay using specific antibodies. The parameters measured reflect the phosphocalcic metabolism well. Serum calcium and the presence of intestinal cabindin testify to the effect of vitamin D on the intestinal absorption of calcium. The calcium content in bone and in serum osteocalcin is representative of mineralization and bone formation.

6) In vitro differentiation study on human osteosarcoma

 The MG-63 cell line is derived from an osteosarcoma of human origin and has the characteristics of osteoblasts (cells of the bone matrix). The cells of this line are used for the evaluation of the hypercalcemic or osteocalcic effect of vitamin D on the bone tissue.

 In this test, the cells are incubated in the presence of increasing concentrations of compounds. After 48 hours of incubation, the concentration of intracellular calcium (flame spectrometer) and osteocalcin (RIA) is determined. Osteocalcin is a specific protein produced by osteoblasts during bone formation; this parameter reflects well the stimulating effect on the bone cells. 7) Study of the formation of plurinucleated cells from bone marrow in culture

 At the bone level, vitamin D influences bone resorption and increases the number of osteoclastic cells. Different systems have been described to assess the activity of vitamin D on bone cells in vitro. A particularly effective system is to determine the formation of multinucleated cells from bone marrow culture, under the inducing effect of vitamin D and its analogs. The multinucleated cells formed under these conditions have all the functional and morphological characteristics of osteoclasts.

 The method used is that described by Ishizuka et al. [27].

Briefly, the bone marrow is removed from mouse femurs and resuspended in MEM (Minimum Essential Medium) culture medium containing 10% fetal calf serum, previously inactivated with heat. The cell suspension is then placed in 24-well multiwell plates, at the rate of 10 ⁶ cells per well (1 ml). The cells are incubated at 37 ° C under an atmosphere of 5% CO ₂ in air. After one day of culture, the culture medium is replaced with fresh complete medium (control culture) or medium containing different concentrations of vitamin D and its analogs (test culture). The medium is renewed every three days. During culture, the number of multinucleated cells

(> 3 nuclei / cell) is determined by counting using an inverted phase contrast microscope. On day 8, the cells are fixed with methanol and stained with Giemsa to allow the morphological study of the cells.

EXAMPLE 27 Biological Properties of the Vitamin D Analogs According to the Invention A) The epoxide function gives analog 1 alpha-hydroxy-vitamin D the characteristic properties of the active metabolite of vitamin D.

By way of example, the biological activity of the epoxide derivatives of vitamin D and of 1 alpha-hydroxy-vitamin D was compared in the test for inducing the differentiation of leukemic cells HL-60.

In this test, cell proliferation is only weakly inhibited by 1-alpha-OHD ₃ . The 50% inhibitory effect (ED50) of

1 alpha-OHD, is obtained for a high extracellular concentration of 3 × 10 ^-6 M. The addition of an epoxide group to 1 alpha-OHD ₃ , for example in position 25 as in the case of compound 24 (1 alpha hydroxy

25,26-epoxy, vitamin D,) allows complete inhibition and differentiation of leukemia cells, and this for significantly lower concentrations. Thus, the biological effect is obtained at the concentration of 3 × 10 ^-8 M, ie 100 times less.

Thus, the presence of an epoxy function in the side chain of 1 alpha-hydroxy-vitamin D, gives it biological properties, in this case cell differentiation, specific to the active metabolite of vitamin D hydroxyl in the side chain (1 alpha, 25- (OH) ₂ D ₃ ). 3) The epoxide analogs of vitamin D exhibit clearly dissociated biological activities with respect to the active natural metabolite of vitamin D, hydroxylated in position 25. For example, the biological activity of the epoxide analogs is compared to that 1 alpha, 25- (OH) ₂ D ₃ in in vitro tests, on human epidermal cells (keratinocytes),

 osteobiastic and leukemic, and in vivo in the rachmque chicken model.

1. Differentiation of leukemia cells

In the HL-60 leukemia cell differentiation induction test, cell proliferation is remarkably inhibited by 1 alpha, 25-hydroxy-vetamin D, and by epoxide analogs of vitamin D. The inhibitory effect 50% 1 alpha, 25- (OH) ₂ D ₃ is obtained for an extracellular concentration of 1.24 × 10 ^-8 M. The epoxide derivatives also show a remarkable inhibition of the proliferation of HL-60 cells. For example, the inhibitory concentration of compound 32 (1 a! Pha-hydroxy-23,24-dehydro-25,26-epoxy vitamin D,) is 1.34 × 10 ^-8 M.

 Thus, the cell differentiation property of vitamin D is preserved by the epoxide analogs, characterized by the presence of an epoxide function in the side chain of the

1 alpha-hydroxy-vitamin D and this even in the absence of the hydroxyl group in position 25.

2. Differentiation of human epidermal cells

 The comparative effect of the analogous epoxides of 1 alpha-OHD on the growth of epidermal cells has been studied on primary cultures of human keratinocytes.

At an ex trace II concentration of 10 ^{- 7} M, the epoxide analogs tested so far, inhibit the growth of at least 45% of the keratinocytes in culture. The 50% inhibitory effect on the growth of keratinocytes is obtained, for example, for extracellular concentrations of 6.2 × 10 ^-7 M and 2.8 × 10 ^-7 M for compounds 30 (1 alpha hy droxy-24,25-epoxy-vιtamιne D3) and 32 respectively. In the same test, the active metabolite of vitamin D, 1 alpha, 25- (OH) ₂ D ₃ , has significantly less effect on the growth of epidermal cells with an ED50 of 3.0 × 10 ^-7 M A significant eff and inhibitor of the epoxide analogs is already observed at the concentration of 10 ^-8 M, while the

1 alpha, 25- (OH) ₂ D ₃ , shows only a marginal effect. For example, compound 26a ((24S, 25l) - 1 alpha, 24-dihydroxy-25,26-epoxy-vitamιne D ₃ ) produces an inhibition of the order of 35% at 10 ^-8 M.

The results obtained show the excellent inhibitory power of epoxide analogs on human keratinocytes in culture, and clearly superior to that of 1 alpha, 25- (OH) ₂ D ₃ , for example by a factor of 5 and 10 respectively for the compounds 30 (1 alpha hydroxy-24,25-epoxy vitamin D3) and 32 (1 alpha hydroxy-23,24-dιdehydro,

25,26-epoxy vitamin D ₃ ).

3. In vitro differentiation effect on human osteosarcoma

 Human osteoblastic cells MG-63, derived from an osteosarcoma, are incubated in the presence of different concentrations of 1 alpha, 25- (OH) -D, and in epoxide analogs. After 48 hours, the secretion of osteocalcin is measured in the culture medium. Under normal culture conditions, EMG-63 cells produce little or no osteocalcin.

1 alpha, 25- (OH) ₂ D ₃ rapidly induces the secretion of osteocalcin by the cells (ED ₅₀ = 1.6 × 10 ^{- 10} M); the optimal effect is obtained at a concentration of 10 ^-9 M. The epoxide analogs are clearly less active than 1 alpha, 25- (OH) ₂ D ₃ Biological activity

50% of the epoxide analogs is therefore observed at much higher extracellular concentrations. For example, the compound 28b (24R,

255) -1 alpha, 24-dihydroxy-25,26-epoxy-vitamin D)) induces only 50% of the maximum secretion of osteocalcin by EMG-63 cells at a concentration of 4.2 × 10 ^-9 M.

REPLACEMENT SHEET Thus, the property of stimulation of the osteoblastic cells of vitamin D is affected by the epoxide derivation of the side chain of 1 alpha-OHD ₃ . The biological effect of the epoxide analogs is obtained at significantly higher concentrations (at least one); at high concentrations, analogs behave like

I alpha, 25- (OH) ₂ D ₃ . There is therefore a dissociation between the effects on cells of bone origin, where the effect is reduced, and the other cells such as keratinocytes or leukemic cells where the effect is preserved or more often considerably increased.

4. Calcifying effect in rickets chicken

The vivo biological activity of vitamin D and its derivatives has been studied in the rickets chicken model. Serum calcium and osteocalcin concentrations were determined after 10 days of treatment of rachitic chickens with 1 alpha, 25- (OH) ₂ D ₃ or the epoxide analogs of 1 alpha-OHD ₃

In the case of 1 alpha, 25- (OH) ₂ D ₃ , the calcium concentration in the blood increases in proportion to the administered dose, reaching normal values in non-rachitic chicken at the daily dose of 80 ng / kg . Serum calcium reflects the calcium absorption of the intestine induced by vitamin D. In the case of epoxide analogs, the pharmacological effect is particularly reduced. For example, no calcium resorption of the intestine is observed for the derivative 26a (24S, 25R) -1 alpha, 24-dihydroxy 25,26-epoxy-vιtamιne D ₃ ) at the daily dose of 160 ng / kg.

Osteocalcin is produced specifically by bone cells, and is an excellent parameter for bone metabolism. 1 alpha, 25- (OH) ₂ D _{3 significantly} stimulates bone metabolism; the maximum effect on serum osteocalcin is obtained at a daily dose of 40 ng / kg. Epoxy derivatives show little or no pnarmacological effects on bone tissue. For example, compound 32

(1 alpha-hydroxy-23,24-dιdehydro-25,26-epoxy-vitamin D,) is completely inactive (tested up to 160 ng / kg) while compound 24 ((24S, 25R) - 1 alpha, 24-dιhydroxy-25,26-époxy-vιtamιne D,) has an activity marginal only at the concentration of 160 ng / kg. Thus, the modifications made to the side chain of 1 alpha-hydroxyvitamin D considerably affect the main pharmacological property of 1 alpha, 25-hydroxy-vitamin D, namely the calcium-calcium metabolism. The calcifying effect of analogs is marginal to nonexistent.

C) The biological properties of the epoxide analogs of vitamin D can be modulated by their respective isomers. In the case of the epoxide analogs of 1-alpha-hydroxy-vitamin D, different isomeric forms are possible both at the level of the epoxide function and at the level of the side chain. Also, the impact of isomerism of epoxide analogs on biological properties has been studied. For example, compounds 26a and 28b were compared in terms of their differentiation properties of epidermal cells and their antiproliferative effects on human tumor cells.

At the level of human epidermal cells, compound 26a inhibits 50% of the growth of keratinocytes at the extra-cellular concentration (ED _5Q ) of _3.1 × 10 ^-7 M. Compound 28b, on the other hand, shows twice less active, with an ED50 of 6.4 × 10 ^{- 7} M. At the concentration of 10 ^-8 M, a significant inhibitory effect is obtained with compound 26a (- 35%) while compound 28b only shows 'a marginal effect.

Regarding the antiproliferative effect on cel lu human tumors, compound 26a inhibits the growth of almost 50% of MCF-7 cells, after 7 days of incubation at the concentration of 10 ^-7 M.

At this same concentration, the antiproliferative effect of compound 28b is reduced by at least a factor of three.

Thus the isomerism of the side chain of epoxv analogs of vitamin D, and particularly in terms of epoxide function, is able to significantly influence their biological activities in naked cell water. These results also show the advantage of considering the pure isomeric forms of the epoxide analogs rather than in the form of a mixture. D) The biological activity of the epoxy analogs of 1 alpha-hydroxy-itamine D may be greater than that of 1 alpha.25-hydroxy-itamine D. Among the interesting biological properties of the vitamin

D and epoxide analogs, the effects on the differentiation of human epidermal cells on the one hand, and the antiproference effects on MCF-7 tumor cells on the other hand, have been considered. For example, compound 32 shows an excellent inhibitory power for cell growth compared to that of the active metabolite of vitamin D, 1 aIpha, 25- (OH) ₂ D _y

On human epidermal cells, compound 32 is found to be at least 10 times more effective in differentiating keratinocytes than 1 alpha, 25- (OH) ₇ D ₃ , with an ED50 of 2.8 × 10 ^-7 M respectively and 3.0 × 10 - ⁶ M. On the other hand, on MCF-7 cells in culture, the antiproliferative effect is also in favor of the epoxy analog. At the concentration of 10 -8 M, the 1 alpha, 25- (OH) ₂ D ₃ is inactive while approximately 20% of cell inhibition is obtained in the case of the compound

32. The biological activity 50% of this analog is observed at the extrateiluiaire concentration of 5.9 × 10 ^-8 M.

 As illustrated with this epoxy analogue, the addition of an epoxide function in the side chain of the alpha alpha-hydroxy-vitamin D is capable not only of retaining the cellular biological properties specific to alpha 1, 25-dihydroxy-vιtamιne D (see B)), but also to increase certain cellular properties characteristic of vitamin D.

E) General biological properties of the epoxy analogs of 1 alpha-hydroxy-vitamin D.

Vitamin D analogs, characterized by the presence of an epoxide function in the side chain, have particularly advantageous in vitro and in vivo biological properties. The epoxide function advantageously replaces the hydroxyl function characteristic of the active metabolite and of analogues of vitamin D. It confers particular biological properties, making it possible to distinguish notably the epoxide derivatives of 1-alpha, 25- (OHLD, and of its main analogs. Thus, the epoxide function makes possible the dissociation between the calcifying effect and the other forms of biological activities.

 The epoxide analogs of 1-alpha-hydroxy-vιtamιne D generally have the cellular properties characteristic of vitamin D. Let us quote in particular the differentiation of leukemic and epidermal cells, the antiproliferative effect on cancer cells and leukocyte cells . Epoxide analogs are particularly effective on epidermal cells and cancer cells; however, they only weakly stimulate the secretion of osteocalcin by cells of osteoblastic origin. As far as the calcium-calcium metabolism is concerned, the calcium-forming effect of the analogues is considerably reduced (marginal activity), even nonexistent in the rachitic chicken model.

 Thus, the notable reduction in the calcifying effect gives epoxid analogs certain advantages compared to vitamin D or its active metabolite, in particular to increase the concentration of compound which can be administered without influencing the calcium-calcium metabolism. This dissociation of activity makes it possible, for example, to stimulate the differentiation of leukemic or epidermal cells without however inducing a toxic deleterious calcifying effect.

The results obtained make it possible to envisage the therapeutic application of epoxide analogues in the treatment of skin conditions, such as psoriasis, secondary hyperparathyroidism (chronic renal disease), and certain cancers (leukemia, lymphoma, myelodisplastic syndrome, melanoma, breast, etc.), or as immunomodulators (suppression of the proliferation of T lymphocytes, differentiation of monocytes, etc.), in particular in autoimmune diseases, inflammatory processes and during transplantation of skin, marrow or organs. REFERENCES

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Claims

 1. Compounds derived from vitamin D or one of its analogs having in particular a side chain grafted in position 17 on the D cycle of vitamin D, characterized in that they comprise an epoxide group grafted on said side chain, epoxy group being separated from position 17 by a straight chain of at least two atoms.

2. Compounds derived from vitamin D or one of its analogs, having a side chain grafted in position 17 on the D ring, said side chain comprising an epoxide group, corresponding to the

 in which

 - V represents a residue of vitamin D or one of its analogs whose position 17 is vacant;

 - X, grafted in position 17 of V, represents a hydrocarbon chain, in particular alkylated, of 2 to 15 carbon atoms optionally substituted or modified, in particular being able to comprise, in one or more positions, one or group (s)

 . hydroxyl, methyl, ethyl, halogen, preferably fluorine,

. ester, in particular a group R COO with R ¹ which represents a linear or branched C ₁ to C ₇ alkyl or alkoxy, saturated or unsaturated, optionally substituted in particular by one or more hydroxy or halogen group (s), preferably fluorine,

. ether, in particular a group R ¹ -O with R ¹ which represents a linear or branched C ₁ to C ₇ alkyl or alkoxy, saturated or unsaturated, optionally substituted by one or more hydroxy or halogen group (s),

. oxo in ketone form,

 . a ring or heterocycle, in particular saturated or unsaturated cycloalkyl, aromatic or heteroaromatic which can carry all the groups and modifications mentioned above, and / or

said chain X which may contain, instead of one or more of its carbon atoms, an oxygen, nitrogen or sulfur atom, said chain X being able to be msaturated, with one or more double (s) or triple (s) carbon-carbon link (s), this msaturated chain being able to carry all the groups and modifications mentioned above, and

 - said chain and the different groups located on the chain can adopt all the isomeric forms,

- the epoxy group

 can be grafted onto any one of the 13 carbon atoms of X, in particular at its end, an epoxide group in which

. R ₁ , R ₂ and R ₃ , which may be identical or different, represent a hydrogen, a C ₁ to C ₁₀ alkyl group, linear or branched, saturated or unsaturated, optionally substituted with one or more halogen group (s), hydroxy, cycloalkyl, also optionally substituted with halogen or hydroxy groups;

. R ₁ and R ₂ can be part of the same cycle, such as carbocycle or heterocycle, and in this case R ₃ has the same meaning as above; . R ₂ and R ₃ may be part of the same cycle, such as carbocycle or heterocycle, and in this case R ₁ has the same meaning as above; . the different isomeric forms at the epoxide level being possible. 3. Compounds according to claim 2, characterized in that they correspond to the formula

in which X, R ₁ to R ₃ have the meanings given in claim 1 and

A represents hydrogen, methyl or the methylene group = CH ₂ , represents a single or double bond,

Y represents H or OH or an ester group, in particular R ¹ COO, or ether, in particular R ¹ O, with R ¹ which has the meaning given in claim 1.

4. Compound according to claim 2 or 3, characterized in that X represents an alkyl chain of 2 to 6 carbon atoms, one carbon atom of which can be replaced by an oxygen atom and optionally substituted, in particular by one or more methyl hydroxyl groups and / or

- ether, in particular by a group R ¹ -O, and X which can be unsaturated with a double or triple carbon-carbon bond,

- the epoxy group being grafted at the end of X, and R ₁ , R ₂ and R ₃ represent cn hydrogen, hydroxyl, an alkyl group, such as methyl or ethyl or hydroxyalkyie.

5. Compounds according to one of claims 2 to 4, characterized in that they respond to the formula

wherein Z represents a saturated or msaturated alkyl chain of 0 to 3 carbon atoms, optionally substituted by hydroxy, an alkyl such as methyl or ethyl on one or more of said carbon atoms. ! e epoxy group being grafted to the end of Z.

6. Compounds according to claim 5, characterized in that they correspond to the isomeric formulas IIa or Ilb

 with

R ₁ R ₂ R ₃ Z

CH ₃ HH -CH ₂ -CH ₂

CH ₃ HH -CH ₂ -CHOH- H CH ₃ CH ₃ -CH ₂ - HHH -C (CH ₃ ) ₂ - CH ₃ HH -CC-

7. Process for the preparation of a compound according to one of the preceding claims, characterized in that the anion obtained from a compound is reacted, the basic structural skeleton of which has the formula IV

and n-butyllithium

with a compound whose structural skeleton has the formula III

in which the reactive functions grafted onto said backbones of III and IV are optionally protected and X, R ₁ , R ₂ , R ₃ , whose reactive functions are optionally protected, have the meanings given in claims 1 to 5,

then said reactive functions are optionally deprotected, in particular from X, R ₁ , R ₂ , R ₃ and hydroxyl in positions 1 and 3.

8. As medicament, a compound according to one of claims 1 to 6. 9. Compound according to one of claims 1 to 6 for the implementation of a method of treatment and / or prophylaxis of cancer, including leukemias, lymphomas, myeiodisplastic syndromes, melanomas, breast, lung and colon cancer, as well as their metastases.

10. Compound according to one of claims 1 to 6 for the implementation of a method of treatment and / or prophylaxis of psoriasis and dyskeratoses. 1 1. Compound according to one of claims 1 to 6 for use as an immunomodulator to prevent rejection of grafts, for use alone or in combination with other compounds such as cyclosponne or FK 506. 12 Compound according to one of claims 1 to 6 for the implementation of a method of treatment and / or prophylaxis of autoimmune diseases. i 3. Compound according to one of claims 1 to 6 for the implementation of a method of treatment and / or prophylaxis of osteoporosis.

14. Compound according to one of claims 1 to 6 for the implementation of a method of treatment and / or prophylaxis of hyperparthyroidism in particular secondary and renal failure.