Highly E-Selective and Enantioselective Michael Addition to Electron-Deficient Internal Alkynes Under Chiral Iminophosphorane Catalysis

摘要

A highly E-selective and enantioselective conjugate addition of 2-benzyloxythiazol-5(4H)-ones to beta-substituted alkynyl N-acyl pyrazoles is achieved under the catalysis of a P-spiro chiral iminophosphorane. Simultaneous control of the newly generated central chirality and olefin geometry is possible with a wide array of the alkynyl Michael acceptors possessing different aromatic and aliphatic beta-substituents, as well as the various alpha-amino acid-derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active alpha-amino acids bearing a geometrically defined trisubstituted olefinic component at the alpha-position.