Highly Z‐Selective Asymmetric Conjugate Addition of Alkynones with Pyrazol‐5‐ones Promoted by N,N′‐Dioxide–Metal Complexes

Highly selective: the title reaction is achieved with high enantiomeric and geometric control and thermodynamically unstable (Z)-enone derivatives are obtained as the major products. The procedure tolerates a wide range of substrates to generate optically active pyrazolones with vinyl-substituted quaternary stereocenters.