Highly E-Selective and Enantioselective Michael Addition to Electron-Deficient Internal Alkynes Under Chiral
Daisuke Uraguchi1, Kohei Yamada1, Takashi Ooi2,3
1Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan).
Abstract:
A highly E-selective and enantioselective conjugate addition of 2-benzyloxythiazol-5(4H)-ones to β-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 β-substituents, as well as the various α-amino acid-derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active α-amino acids bearing a geometrically defined trisubstituted olefinic component at the α-position.
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