Electrocyclic Ring-Opening/p-Allyl Cation Cyclization Reaction Sequences Involving gem-Dihalocyclopropanes as Substrates: Application to Syntheses of (+)-, (+)-, and (-)-g-Lycorane

Abstract

The readily prepared gem-dibromocyclopropanes (±)-13 and (±)-19 each engage in a silver(I)-promoted electrocyclic ring-opening/π-allyl cation cyclization sequence to deliver the hexahydroindole (±)-20, which participates in a Suzuki cross-coupling rea