Copolymerization Characteristics of Two Vinylsilanes
作者:Charles E. Scott、Charles C. Price
DOI:10.1021/ja01520a019
日期:1959.6
Unexpected Steric Effects of “Remote” Alkyl Groups on the Rate of Conjugate Additions to Alkyl α,β-Ethylenic Sulfones, Sulfoxides, and Esters
作者:Aimee R. Usera、Gary H. Posner
DOI:10.1021/jo062155g
日期:2007.3.1
size of the heteroatom-attached alkylgroup affects the rate of conjugate addition. Molecular modeling strongly suggests that what are generally considered to be “remote” alkylgroups in −CβHCαHS(O)nalkyl systems and −CH2CβHCαHCOOalkyl systems are actually not remote from the β-carbon atom of the Michael accepting unit. Molecular modeling clearly shows that the alkylgroups in these Michael acceptors shield
在迈克尔型加成反应中对共轭乙烯砜,亚砜和酯的检测首次显示,杂原子连接的烷基的大小会影响共轭添加的速率。分子建模有力地表明,什么通常被认为是“远程”中的烷基-C β ħ Ç α HS(O)ñ烷基系统和-CH 2 C ^ β ħ Ç α HCOO烷基系统实际上是从β-不远程迈克尔接受单元的碳原子。分子模型清楚地表明,这些迈克尔受体中的烷基按以下顺序屏蔽了β-碳:Et < i -Pr < t-Bu 竞争实验确定迈克尔加成的相对比率按以下顺序排列:Et> i -Pr> t -Bu。