Copper-Catalyzed Divergent Addition Reactions of Enoldiazoacetamides with Nitrones

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.