Copper-catalyzed multicomponent assembly of γ-butenolides the interception of carbonyl ylides with iminium ions.

A Cu(I)-catalyzed three-component reaction of cyclopropenes, enamines and aldehydes has been realized. This reaction proceeds the interception of carbonyl oxonium ylide intermediates with α, β-unsaturated iminium ions that are generated from enamines and aldehydes under the catalysis of Cu(MeCN)PF, leading to the desired γ-butenolide derivatives in good yields and with moderate diastereoselectivities. Access to these derivatives with tethered ketone and alkynal groups will expand the structural diversity of multi-substituted butenolides.