Ni(0)-catalyzed conjugate addition of Me3SiCN to ynones: alpha-bromo-beta-cyano tetrasubstituted enones.
Conjugate addition of Me(3)SiCN to ynones is smoothly catalyzed by Ni(cod)(2) to give the beta-cyanosilyloxyallene quantitatively. Further reaction of the silyloxyallenes with NBS provides the tetrasubstituted alpha-bromo-beta-cyano enones in high yields (up to 95%) with excellent Z-selectivity (E/Z = up to >1/99). X-ray crystallographic analysis showed a bent structure of the alpha-bromo-beta-cyano enone due to a deconjugation of the pi-bond and carbonyl group.
Arai
Takayoshi
T
Department of Chemistry, Graduate School of Science, Chiba University, Inage 1-33, Chiba 263-8522, Japan. tarai@faculty.chiba-u.jp
Suemitsu
Yuuki
Y
Ikematsu
Yui
Y