Alkynenitriles: stereoselective chelation controlled conjugate addition–alkylations
作者:Fraser F. Fleming、Venugopal Gudipati、Omar W. Steward
DOI:10.1016/s0040-4020(03)00765-8
日期:2003.7
Chelation-controlled conjugate addition of Grignard reagents to γ-hydroxyalkynenitriles stereoselectively generates tri- and tetra-substituted alkenenitriles. t-BuMgCl-initiated deprotonation of hydroxyalkynenitriles followed by addition of a second Grignard reagents triggers a facile conjugate addition leading to a cyclic magnesium chelate. Protonation of the chelate stereoselectively generates trisubstituted
将格氏试剂螯合控制的共轭加成到γ-羟基炔腈中,立体选择性地生成三取代和四取代的烯腈。由t -BuMgCl引发的羟基炔腈去质子化反应,然后添加第二种格氏试剂,触发了便捷的偶联物添加,从而形成了环状镁螯合物。螯合物的质子化立体选择性地产生三取代的腈,而t -BuLi的添加导致转化为“酯”配合物,该配合物允许与醛亲电子试剂进行烷基化。螯合控制的共轭加成烷基化反应生成三取代和四取代的烯腈,否则很难合成。