With the IR-spectroscopy method and the quantum-chemical AM1 method, the ∆ 22 and ∆ 23 steroids containing a hydroxyl group at C 20 or C 22 have been studied in order to elucidate the mutual arrangement in space of the hydroxyl group and of the double bond in the side chain of the molecules. The conformational analysis of steroid alcohols has been performed and the population of their stable conformers has been calculated. The frequencies of the bands in the IR spectra of alcohols in the region of the stretching vibration of OH groups have been assigned to certain conformers and the possibility of formation of the intramolecular hydrogen bond of the OH groups with the π-electron cloud of C=C bonds has been analyzed.Keywords: stretching vibrations of OH, unsaturated steroid alcohols, alcohol conformers, intramolecular hydrogen bond.Introduction. Terminal steroid alkenes (22-and 23-ens) are of interest in nitryloxide synthesis of biologically active modified steroids, the side chain of which contains a 2-isoxazoline fragment [1-3]. Addition of nitryloxides to steroid alkenes proceeds in regio-and stereoselective ways, with the degree of stereoselectivity depending substantially on the character of substitution at C 20 and C 22 , in particular, on the presence of a hydroxyl group in the allylic position [4][5][6]. To elucidate the characteristic features of the behavior of such steroid alcohols with the end C=C bond in the reaction of interaction with nitryloxides, it is necessary to carry out a detailed investigation of their spatial structure, including the mutual disposition of the hydroxyl group and double bond.In the present work, we carried out an IR spectroscopic investigation and a conformational analysis of tertiary ∆ 22 and ∆ 23 steroid C 20 alcohols 1 and 2 with a different spacing between the OH group and C=C bond as well as
Isoxazoline derivatives of steroids are of considerable synthetic interest because cleavage of the isoxazoline moiety gives way to the formation of functionalized steroids, which may serve as useful synthons in steroid chemistry.
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