Diastereodivergent synthesis of 3-spirocyclopropyl-2-oxindoles through direct enantioselective cyclopropanation of oxindoles

Abstract

Falling like dominos: The first direct organocatalytic asymmetric cyclopropanation reaction of oxindole was developed, in which oxindoles were employed as a dinucleophilic C 1 synthon and bromonitroolefins with a dielectrophilic center were used as a C 2 synthon (see scheme). An amino acid based multifunctional catalyst promoted the [2+1] reaction, giving the products in high yields and excellent enantioselectivities. A divergent synthesis of different stereoisomers of 3-spirocyclopropyl-2-oxindoles was achieved. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.