Catalyst-controlled
divergent addition reactions of enoldiazoacetamides
with nitrones have been developed. By using copper(I) tetrafluoroborate/bisoxazoline
complex as the catalyst, a [3+3]-cycloaddition reaction was achieved
with excellent yield and enantioselectivity under exceptionally mild
conditions, which represents the first highly enantioselective base-metal-catalyzed
vinylcarbene transformation. When the catalyst was changed to copper(I)
triflate, Mannich addition products were formed in high yields with
near exclusivity under otherwise identical conditions
