Synthesis of pentacyclic steroids via tandem stille coupling and diels-alder reactions

摘要

Tandem Stille coupling and Diels-Alder reaction of steroidal iodoalkenyl substrates [17-iodoan- dorsta-16-ene (2), 17-iodo-3-keto-4-methyl-4-azaandrosta-16ene (10), and 17-iodo-3-keto-4-azaan- drosta-16-ene (11)] were examined in the presence of vinyltributyltin, a dienophile (diethyl maleate, methyl acrylate, dimethyl acetylenedicarboxylate, diethyl fumarate, (-)-di[1R]-menthyl]fumarate, maleic anhydride), and a palladium catalyst.