A Brønsted acid catalyzed tandem reaction for the diastereoselective synthesis of cyclobuta-fused tetrahydroquinoline carboxylic esters.

A novel Brønsted acid catalyzed tandem reaction provides highly functionalized cyclobuta-fused tetrahydroquinoline carboxylic esters from anilines and 2-alkylenecyclobutanones in good to high yield. During the reaction a dynamic diastereoselective cyclization is achieved, resulting in the formation of three contiguous stereocenters with high stereoselectivity.