Gold-Catalyzed Michael-Type Reactions and [4 + 2]-Annulations between Propiolates and 1,2-Benzisoxazoles with Ester-Directed Chemoselectivity.

This work reports gold-catalyzed reactions between 1,2-benzisoxazoles and propiolate derivatives with ester-controlled chemoselectivity. For ethyl propiolates 1', their gold-catalyzed reactions afforded Michael-type products 4, whereas tert-butyl propiolates 1 preferably underwent [4 + 2]-annulations, further yielding 6 H-1,3-oxazin-6-one derivatives 3.