Stereoselective heterocycle synthesis through a reversible allylic alcohol transposition and nucleophilic addition sequence

Abstract

The abilities of Re₂O₇ to promote non-stereoselective allylic alcohol transposition reactions and acetal ionization or enone activation have been coupled for a heterocycle synthesis in which thermodynamics dictate stereochemical outcomes. The stabilities of intermediate allylic cation and oxocarbenium ion intermediates dictate the efficiency of product equilibration. Long range stereoinduction can be observed in the synthesis of spiroketals and spirotricycles through this protocol.