Lewis Acid Catalyzed Stereoselective Dearomative Coupling of Indolylboron Ate Complexes with Donor-Acceptor Cyclopropanes and Alkyl Halides

Indolylboron ate complexes readily generated from 2-lithioindoles and boronic esters underwent multicomponent dearomative coupling with D-A cyclopropanes and alkyl halides in the presence of Sc(OTf)(3) as a catalyst. The reactions proceeded with complete diastereoselectivity and excellent stereospecificity to provide indolines containing three contiguous stereocenters. The valuable boronic ester moiety remains in the product and allows for subsequent functionalization.