Diversity-oriented one-pot multicomponent synthesis of chromanone-based 3,3′-pyrrolidinyl-spirooxindoles via a 1,3-dipolar cycloaddition reaction

A new methodology was developed for the highly efficient one-pot multicomponent synthesis of chromanone-based 3,3'-pyrrolidinyl-spirooxindoles via a 1,3-dipolar cycloaddition reaction of chromones 1 with azomethine ylides (thermally generated in situ from isatins and proline or thioproline). Another valuable application of this method was for the less reactive chromone through a carboxylic acid-activation and then decarboxylation strategy, which enabled diversity-oriented synthesis of complex pirooxindoles bearing four contiguous stereocenters (one of which is a spiro quaternary stereocenter) with high efficiency and stereoselectivity (up to 90% yield and 20:1 d.r.). This protocol could provide libraries of stereochemically rich and multiple pharmecore collections, that will help in search for new drug-like molecules. (C) 2018 Elsevier Ltd. All rights reserved.