Sc(OTf)3-Catalyzed Chemodivergent Annulations of γ-Butyrolactone-Fused Cyclopropanes with Anthranils.

The Lewis acid-catalyzed annulations between anthranils and γ-butyrolactone-fused donor-acceptor cyclopropanes have been developed. Depending on the anthranils used, such annulations proceeded in a chemodivergent way to produce either bridged cyclic products via [4 + 3] annulation or γ-butyrolactone-fused tetrahydroquinoline products via a cascade process in moderate to high yields. A probable mechanism for the two reaction pathways has been proposed. The reaction could be performed on a gram-scale, and the products could be elaborated to other useful cyclic structures bearing multiple contiguous stereogenic centers.