Chelation between gamma-hydroxy unsaturated nitriles and Grignard reagents promotes an otherwise difficult anionic conjugate addition reaction. The intermediate chelate is readily generated by deprotonation with t-BuMgCl followed by the addition of a second Grignard reagent that triggers an intramolecular conjugate addition. Structurally diverse Grignard reagents add with equal efficiency, providing an intermediate
作者:Fraser F. Fleming、Qunzhao Wang、Zhiyu Zhang、Omar W. Steward
DOI:10.1021/jo0258150
日期:2002.8.1
Grignard and organolithium reagents to gamma-hydroxy-alpha,beta-alkenenitriles promotes efficient conjugateadditions to what are otherwise recalcitrant Michael acceptors. Sequential deprotonation and addition of a modest excess of a second Grignard reagent allows effective conjugate delivery of alkyl groups to cyclic and acyclic alkenenitriles. Mechanistically, conjugateadditions proceed through alkylmagnesium