Asymmetric [3+2] annulations of 1,4-di-thiane-2,5-diol and oxindole ketimines

An efficient asymmetric [3+2] annulation reaction with respect to isatin N-Boc ketimines and 1,4-di-thiane-2,5-diol has been achieved by using a chiral tertiary-amine squaramide catalyst, which delivering the spirocyclic 3-aminooxindoles in very good yields (up to 95%) with moderate to good diastereoselectivities (up to 9:1 dr) and very good enantioselectivities (up to 97% ee). (C) 2016 Elsevier Ltd. All rights reserved.