R. I. Yakhimovich

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Vitamin D 3 (cholecalciferol) is p repa red by the photochemical convers ion of 7-dehydrocholes tero l (1) into the provi tamin and thermal i somer iza t ion of the la t te r . A complex mixture of photoderivatives of I and their oxidation products is fo rmed as a resu l t of these react ions . The isolat ion of crysta l l ine cholecalciferol or its complex(More)
During the dehydrobromination of this mixture of bromo derivatives, the benzoate of cholesta-5,7-dien-36-ol (IV) (D3 provitamin) is formed, as well as side products, the benzoate of cholesta-4,6-dien-36-ol (V) and cholesta-2,4,6-triene (VI) [3, 4], In several cases, other reaction products, i.e., the benzoates of cholesta-6~8(14)-dien-38-ol (VII) [5],(More)
(!!f) did not display the effects typical of (la) and (Ib)~ ~in small doses, they were with~ out significant effects on blood circulation, and in larger do~es up to 5~i0 mg/kg they caused a temporary reduction in arterial pressure which was apparently due to a ganglion~blocklng effect, since during ~ hypotens!on induced by (Ic, Ilb, Ild) and (IIf), the(More)
It has been established that the fluorination of 3β-hydroxy-Δ5,7-steroids, unlike that of 3β-hydroxy-Δ5-steroids, does not lead to the formation of 3β-fluoro derivatives. The reaction products are 3α,5α-cyclo-Δ6,8(14) compounds. Consequently, to obtain the 3β-fluoro derivatives of provitamins D — 7-dehydrocholesterol and ergosterol — the 5,7-diene system(More)
The influence of various sources of ultraviolet radiation on the photoisomerization of provitamins D--ergosterol and 7-dehydrocholesterol--was studied under industry-like conditions. The yield of previtamins and, consequently, vitamins D was higher with the use of erythemic lamps with luminophore E-2 and luminophore E-3 than with the use of lamps PRK-2.
In [1] we repor ted that cho l e s t a -5 ,7 -d i en -3P-o l benzoate (II) is fo rmed in suf f ic ien t lyhighyie ldwhen 7 -b romocho le s t -5 en -3 /~ -o l (!) is dehydrobromina ted with sodium bicarbonate in the p re sence of a catalyt ic amount of ~ -p ico l ine . This react ion is eas i ly c a r r i e d out under industrial conditions al~d is used in(More)
It has now been established that most of the vitamin D ethers and esters are devoid of biological activity. Only those that are readily hydrolyzed in the organism are active. The latter include the acetate, ethyl carbonate, phosphate, butyrate, sulfate, and palmitate. Biologically active esters of vitamins D2 and D3 are attracting the attention of many(More)
I. Yu. A. Azev, I. I. Mudretsova, E. L. Pidemskii, et al., Khim.-farm. Zh., No. i0, 12021205 (1985). 2. A.B. Koshokov, I. V. Iselinskii, and Yu. A. Arevkov, Zh. Org. Khim., 15, No. 6, 1331 (1980). 3. Methods in Experimental Chemotherapy [in Russian], G. N. Pershin (ed.), 2nd edn~ Moscow (1971). 4. J.R. Dudley, J. T. Thurston, F. C. Schaefer, et al., J. Am.(More)
Ethers and esters of vitamin D are completely devoid of antirachitic activity (apart from those which are easily hydrolyzed in the organism [i]). Substitution of the hydroxyl group by a thiol group [2] or by chlorine or bromine atoms [3] also leads to loss of activi-ty. However, it is known that introduction of fluorine into the molecule of a steroidal(More)
The study of vitamin D esters commenced in 1927-1928 [18, 21], and up to the present, they remain of interest to many researchers [8, 13, 17]. There are many reasons for this interest. First of all, some of the investigate d vitamin D 2 and D~ esters have antirachitic activity [3, 7]. It has also been shown that part of the vitamin D 3 in the organism is(More)