The conjugate addition of mixed alkyl cuprates to ethyl propiolate generates substituted [a- (carboethoxy)-vinyljcuprates that readily react with acid chlorides of a, p-unsaturated acids to produce a, a '-dienones. These unsaturated ketones bearing an a-carboethoxy group can serve as precursors to annulated cyclopentenones via a Nazarov-type cyclization. With this two-step sequence, it is possible to efficiently prepare substituted cyclopentenones fused ...
