Mono- vs. dialkylation of carbanions. Effects of absolute and relative acidity of the conjugate carbon acids in selectivity control
作者:Luděk Ridvan、Jiří Závada
DOI:10.1016/s0040-4020(97)00989-7
日期:1997.10
in the reaction of the dibromide 1 with carbanions 2a – 2g covering a range greater than 15 pK units in DMSO. It was found that the bis(monoalkylated) product 3 arises exclusively or predominantly from the carbanions 2d – 2g derived from the less acidic carbon acids 7d – 7g whereas the cyclic product of dialkylation 4 prevails in the reaction of the carbanions 2a – 2c derived from the more acidic carbon
在二溴化物1与碳数2a-2g的反应中研究了标题问题,碳数2a-2g在DMSO中的作用范围大于15 pK单位。已发现,双(单烷基化)产物3完全或主要来自于较弱酸性碳酸7d – 7g产生的碳负离子2d – 2g,而二烷基化4的环状产物主要存在于衍生自其的碳负离子2a – 2c的反应中。酸性更高的碳酸7a – 7c。因此,烷基化选择性主要取决于参与反应的碳酸的绝对酸度。该小说的原理,以及在较早的研究基础上,根据等式提供了意外的发现。(1)–(4)。