Electrophile-induced generation of cyclic azomethine imines from steroidal δ-alkenyl hydrazones

Novel δ-alkenyl phenylhydrazones were synthesized in both the estrone and the 13α-estrone series. Electrophile-induced cyclizations of alkenyl phenylhydrazones with phenylselenyl bromide furnished cyclic iminium salts, via attack of the imino nitrogen atom on the intermediate seleniranium ion. Hydride reduction of the iminium salts led to novel aminophenyl-substituted aza-D-homoestrones. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI-MS techniques, with C70 fullerenes as matrix in the latter case.