Catalytic asymmetric formal [3+2] cycloaddition of isatogens with azlactones to construct indolin-3-one derivatives.

The chiral amide–guanidine-catalyzed asymmetric formal [3+2] cycloaddition of isatogens with azlactones is presented. This strategy provided a facile and feasible route to chiral indolin-3-one derivatives bearing two contiguous tetrasubstituted stereocenters in moderate to good yields with high diastereoselectivities and enantioselectivities. A possible working mode was proposed to elucidate the chiral control of the process.