This article is dedicated to Prof. H. Ila on the occasion of her 80th birthday.
A dearomatization-guided and (3+2) cycloaddition-triggered annulation reaction of in situ formed isoquinolinium ylides with sulfamate-derived cyclic imines is reported, offering a cogent synthesis of tetracyclic 1,3-benzoxazepine frameworks in high yields. The protocol features successive ring-forming and ring-breaking events in a cascade fashion and is also scalable.
Key words
cascade annulation - dearomatization - benzoxazepines - (3+2) cycloaddition - heterocycles