Potentially carcinogenic cyclopenta[a]phenanthrenes. Part VII. Ring-D diols and related compounds

Abstract

Elimination from 16,17-dihydro-17-tosyloxy-15H-cyclopenta[a]phenanthrene and from its 15-tosyloxy-isomer in dimethyl sulphoxide at 100° gave, respectively, 15H- and 17H-cyclopenta[a]phenanthrenes whereas, contrary to a previous report, elimination from the former in boiling collidine led to a 1 : 1 mixture of the two olefins. Dehydrogenation of 16,17-dihydro-15H-cyclopenta[a]phenanthrene with DDQ also led to a mixture of the 15H- and 17H-olefins. Elimination from 16,17-dihydro-11-methyl-17-tosyloxy-15H-cyclopenta[a]phenanthrene in boiling collidine yielded only the 11-methyl-15H-olefin. Oxidation of these olefins with osmium tetroxide gave cis-diols, whereas trans-diols were obtained by reduction of the corresponding 16-hydroxy-17-ketones with sodium borohydride. Unconjugated 16-ketones resulted from acid-catalysed dehydration of these diols.