Nickel(II)-Catalyzed Enantioselective 1,3-Dipolar Cycloaddition of Nitrones with α,β-Unsaturated Acylcarboxylates

The highly enantioselective 1,3-dipolar cycloaddition of nitrones with alpha,beta-unsaturated acylcarboxylates was realized for the first time by using a chiral bis(indano-oxazoline)-based Ni complex. The reaction proceeded smoothly under mild conditions and provided isoxazolidines with three contiguous stereocenters in high yields with excellent diastereoselectivities (> 20: 1 dr) and enantioselectivities (up to 99 % ee). The reaction was scaled up to the gram scale, and the products were readily transformed into gamma-amino alcohols and other potentially bioactive compounds.