A domino [3 + 2] cycloaddition/deamination/imine hydrolysis reaction of cyclopropyl spirooxindoles with thiourea for access to spiro-γ-thiolactone oxindoles

Abstract

A domino [3 + 2] cycloaddition/deamination/imine hydrolysis reaction of D–A cyclopropane with inexpensive thiourea catalyzed by Lu(OTf)₃ has been developed. A series of γ-thiolactone spirooxindole compounds with potential biological activity were obtained in up to 98% yields. Experiments to investigate the mechanism showed that γ-thiolactone products were from the hydrolysis of the imine intermediates. In addition, the asymmetric catalytic reaction of D–A cyclopropane and thiourea has been successfully developed to afford spiro-γ-thiolactone compounds with good enantioselectivities (up to 98% ee). The utility of this method was showcased by the facile transformation and biological activity of products.