Base-Promoted Tandem Reaction towards Conjugated Dienone or Chromone Derivatives with a Cyano Group: Insertion of Alkynes into C-C sigma-Bonds of 3-Oxopropanenitriles

摘要

Base-promoted insertion reactions of alkynes into the C-C sigma-bonds of -cyano ketones were established to construct highly functionalized conjugated olefins or chromone derivatives via transition metal-free tandem reactions. These reactions are initialized through the nucleophilic attack of -cyano ketones to alkynones followed by intramolecular nucleophilic addition/ring-opening to furnish the cyano-containing alkenes. In the cases of alkynones bearing an ortho-halide-substituted aryl ring, a further C-O bond coupling reaction occurs to afford chromone derivatives in good to high yields. Various alkynones bearing alkyl or aryl substituents were compatible in the reaction. This reaction has the potential to become a general synthetic protocol for the preparation of cyano-substituted olefins and chromones due to the abundance of easily accessible starting materials possessing diverse substituent groups.