Lewis acid catalysed asymmetric cascade reaction of cyclopropyl ketones: concise synthesis of pyrrolobenzothiazoles

Utilizing the C4 reactive site of cyclopropyl ketones and a chiral N,N'-dioxide-scandium(iii) complex as a catalyst, a concise ring-opening/cyclization/thio-Michael cascade method was developed for the synthesis of chiral benzothiazole derivatives from a simple 2-aminothiophenol material. The kinetic resolution and the origin of stereoselectivity were elucidated via a possible catalytic model.