Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
J Org Chem. 2017 Feb 17;82(4):2300-2305. doi: 10.1021/acs.joc.7b00053. Epub 2017 Feb 8.
Competition experiments demonstrate that additions of allylmagnesium halides to carbonyl compounds, unlike additions of other organomagnesium reagents, occur at rates approaching the diffusion rate limit. Whereas alkylmagnesium and alkyllithium reagents could differentiate between electronically or sterically different carbonyl compounds, allylmagnesium reagents reacted with most carbonyl compounds at similar rates. Even additions to esters occurred at rates competitive with additions to aldehydes. Only in the case of particularly sterically hindered substrates, such as those bearing tertiary alkyl groups, were additions slower.
竞争实验表明，烯丙基卤化镁对羰基化合物的加成反应速率非常接近扩散速率极限，与其他有机镁试剂的加成反应不同。烷基镁和烷基锂试剂可以区分电子或空间上不同的羰基化合物，而烯丙基镁试剂与大多数羰基化合物的反应速率相似。即使与酯的加成反应速率也与醛的加成反应速率相当。只有在特别受空间位阻影响的底物（如带有叔烷基的底物）的情况下，加成反应才会较慢。
