Synthesis and conformation of four 16,17-diols in the 3-methoxy-13α-estra-1,3,5(10)-triene series
作者:Sigfrid Schwarz、Bruno Schönecker、Kai Fritsche、Andreas Poser、Corinna Lange、Wolfgang Günther、Stephan Göttke、Helmar Görls、Siegfried Bäsler
DOI:10.1016/s0039-128x(02)00175-7
日期:2003.2
All four diasteromeric 16,17-diols in the 3-methoxy-13alpha-estra-1,3,5(10)-triene series have been synthesized. The trans-diols 1 and 2 can be obtained by hydroborating the 17-enol acetate 6 (61%, ratio 27:73, preferred alpha attack). OsO4 dihydroxylation of the olefin 7 ;yielded the cis-diols 3 and 4 (ratio 13:87). The dihydroxylation proceeds with preference for beta attack caused b a C-ring twist-boat form of 7. The conformations of the diols 2 and 4, the 17-benzyl-17-hydroxy compounds 9 and 10 (obtained by Grignard reaction), and the 16alpha-bromo-17beta-hydroxy compound 8 were determined by X-ray analysis and by H-1 NMR spectroscopy in solution. Some compounds, in spite of a 17beta-hydroxy group, had a conformation with a ring C chair form (4, 8, 9) caused by intermolecular interaction in the solid state. The rest of the compounds studied here (2, 10) possessed a conformation with a ring C twist-boat form, which has been also found for all 1beta-substituted compounds in solution. The preferred conformation of the D-ring with 17beta-substituents seems to be the 16beta-envelope form or near this form, but the existence of the 16beta-envelope form (inversion of the ring D) for some compounds showed great variance in the conformation of ring D, which is substituent dependent. (C) 2002 Elsevier Science Inc. All rights reserved.