Chemoselectivity as a Delineator of Cuprate Structure in Catalytic 1,4-Addition of Diorganozinc Reagents to Michael Acceptors
作者:Matthias Welker、Simon Woodward、Luis F. Veiros、Maria José Calhorda
DOI:10.1002/chem.200903310
日期:2010.5.17
of this SR‐protected 1,4‐benzoquinone has been compared with the behavior of the analogous OR‐protected acetal in copper‐catalyzed additions of ZnMe2 by using chiral phosphoramidite ligands. The activation energy for 1,4‐methylation of the latter OR‐acetals with ZnMe2 (>95 % ee) has been determined for two CuX2 pre‐catalysts (X=OAc, 12.2 kcal mol−1; X=OTf, 6.7 kcal mol−1; Tf=triflate). The dithioacetal