An experimental and theoretical reinvestigation of the Michael addition of primary and secondary amines to dimethyl acetylenedicarboxylate
作者:Asha Gurjar、Priyadarshni Poonia、Pragya Sinha、Raj K. Bansal
DOI:10.1016/j.tetlet.2014.03.013
日期:2014.4
Theoretical calculations of the Michael addition of diethylamine, pyrrolidine, and benzylamine to DMAD at the DFT (B3LYP/6-31+G∗) level indicate that the reaction follows a stepwise mechanism via a zwitterionic intermediate. The reactions have low activation barriers, 13–15 kcal mol−1 and are exothermic, ΔH° = −29 to −44 kcal mol−1. The detailed investigation of the reaction of benzylamine with DMAD
A straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acids was demonstrated in this manuscript. The present protocol can be regarded as a straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acid. Moreover, the reaction is fundamentally new chemistry for the sp(3) C-N bond cleavage coupled with esterification. The esterification reaction conditions are very mild and functional group-tolerated, such as hydrosilanes, alcohols, phenol, and amino acids. A mechanism is proposed in which the tertiary amine reacts with dimethyl but-2-ynedioate to form zwitterionic salt, and then the zwitterionic intermediate subsequently accept hydrogen to assist the nucleophilic attack of oxygen atom of carboxyl group at the benzyl group of tertiary amine, while a separate reaction pathway leads to esterification. (C) 2012 Elsevier Ltd. All rights reserved.