[X-ray diffraction studies on the configuration of 2 xi, 17 alpha-diethynyl-2 xi, 17 beta-dihydroxy-A-nor-5 alpha-androstane alpha-epimer].

X-ray diffraction studies on the configuration of 2 xi, 17 alpha-diethynyl-2 xi, 17 beta-dihydroxy-A-nor-5 alpha-androstane "alpha-epimer" that possessed antifertility effect and estrogen activity were reported. Pure alpha-epimer was obtained by recrystallization and low pressure silica gel column chromatography combined with HPLC method. Its structure was identified by IR, MS, 1HNMR. The configuration was determined by single crystal X-ray diffraction analysis. The crystal of alpha-epimer belonged to orthorhombic, the space group was P222(1), with the following crystallographic parameters: a = 6.777 (2), b = 12.125 (4), c = 25.292 (8)A, V = 2078.5(1.2)A3, Z = 4. One thousand two hundred and thirty-five independent reflections with I greater than or equal to 3 sigma (I) were collected on a Nicolet R3M/E four-circle diffractometer by means of MoK alpha radiation. The structure was solved by direct method and refined by least square technique to a final discrepancy factor of R = 0.039. The molecule was shown to consist of the alpha-configuration of C2 and C17ethynyl groups. The absolute configuration was deduced by the absolute configuration of synthetic raw material, conformation analysis and the study of 1HNMR. The absolute configuration of asymmetric centers were 2R,5S,8R,9S,10S,13S,14S,17R.