The Curtius Rearrangement of Cyclopropyl and Cyclopropenoyl Azides. A Combined Theoretical and Experimental Mechanistic Study
作者:Vinod Tarwade、Olga Dmitrenko、Robert D. Bach、Joseph M. Fox
DOI:10.1021/jo801104t
日期:2008.11.7
A combined experimental and theoretical study addresses the concertedness of the thermal Curtius rearrangement. The kinetics of the Curtius rearrangements of methyl 1-azidocarbonyl cycloprop-2-ene-1-carboxylate and methyl 1-azidocarbonyl cyclopropane-1-carboxylate were studied by (1)H NMR spectroscopy, and there is close agreement between calculated and experimental enthalpies and entropies of activation
实验和理论相结合的研究解决了库尔修斯热重排的协调性问题。用(1)H NMR谱研究了1-叠氮基羰基环丙-2-烯-1-甲酸甲酯和1-叠氮基羰基环丙烷-1-甲酸甲酯的库尔修斯重排动力学,计算的焓与实验焓密切相关。和激活熵。在这些相同的酰基叠氮化物上进行的密度泛函理论(DFT)计算(B3LYP / 6-311 + G(d,p))显示出27.8 kcal / mol和25.1 kcal / mol的气相屏障。相比之下,用于重排乙酰基,新戊酰基和叠氮化物的气相活化能垒分别为27.6、27.4和30.0 kcal / mol。乙酰叠氮化物在CCSD(T)/ 6-311 + G(d,p)浓度下协调一致的Curtius反应的势垒显示出26的可比活化能。3 kcal / mol。本征反应坐标(IRC)分析表明,所有重排均通过协调的途径发生,并伴有N2的损失。相对于1-叠氮羰基羰基环丙烷-1-羧酸甲酯而言,1-