The X-ray investigation of 16 alpha,17 alpha-thiazolidine derivatives of delta 4- and delta 5-pregnanes and conformational analysis of their oxathiolane analog |
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Authors: | S V Lindeman T V Timofeeva V E Shklover Y T Struchkov A M Turuta A V Kamernitzky |
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Institution: | A.N.Nesmeyanov Institute of Organoelement Compounds, Academy of Sciences of the USSR, 28, Vavilov str., Moscow,USSR117813,;N.D.Zelinsky Institute of Organic Chemistry, Academy of Sciences of the USSR, 47, Leninsky Prospekt, Moscow, 117813, USSR |
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Abstract: | An X-ray study of 3,20-dioxo-4-pregnene-16 alpha,17 alpha-d]--2',2'-dimethylthiazolidine (I) and 3 beta-hydroxy-20-oxo-5--pregnene-16 alpha,17 alpha-d]-2',2'- dimethylthiazolidine (II) has been carried out. Two independent molecules in crystal II have significantly different conformations of the D and E rings, although according to the atom-atom potential calculations the energy of interaction of these molecules with their neighbors in crystal is the same. The calculation of conformational energy of 3,20-dioxo-4-pregnene-17 alpha,16 alpha-d]-2',2'--dimethyloxathiolane (III) by the molecular mechanics method (MMM) indicates a possibility of existence of two similar conformers also for this molecule. The MMM calculation shows also that the conformation of molecule III (as well as progesterone) with the 17 beta-acetyl group torsion angle C(16)C(17)C(20)0(20) close to -120 degrees is possible. |
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