New synthetic methodology for ring expansion of n-sized conjugated cycloalkenones into homoallylic n+3 lactones:three-step synthesis of fragrant phoracantholide

摘要

Under the influence of Lewis acidic boron trifluoride-diethyl etherate,epoxides are activated sufficiently to undergo rapid nucleophilic opening by ketone enolate ions at -78 deg C,forming useful #gamma#-lactols.Application of this protocol to N+3 ring expansion features one-flask,multicomponent,sequential reactions.