Asymmetric Access to Spirobenzofuran Oxindoles via Organocascade Reaction of Unprotected 3-Chlorooxindoles with 2-Hydroxy-β-Nitrostyrenes.

Abstract

A highly enantioselective methodology has been developed to access oxindole-fused spiro dihydrobenzofuran, applicable to a protecting-group-free reactant, with high bond efficiency (1 new C-C and 1 C-O bond) and two contiguous stereocenters. Gram-scale and stereodivergent synthesis without compromising yield and selectivity illustrates the potential practicality of the protocol. Dynamic HRMS titrations were conducted to propose the reaction mechanism.