Experimental and computational evidence for α-lactone intermediates in the addition of aqueous bromine to disodium dimethyl-maleate and -fumarate
作者:Necmettin Pirinççioğlu、James J. Robinson、Mary F. Mahon、J. Grant Buchanan、Ian H. Williams
DOI:10.1039/b711538e
日期:——
of bromine to aqueous solutions of disodium 2,3-dimethylmaleate and 2,3-dimethylfumarate reveals stereochemistries opposite to those originally assigned in 1937: cis alkene yields erythro lactone, and trans alkene yields threo lactone. B3LYP/6-31+G(d) calculations using a PCM description of aqueous solvation confirm the validity of our proposed mechanism, in which the first-formed intermediate in each
通过将溴添加到2,3-二甲基马来酸二钠和2,3-二甲基富马酸二钠水溶液中获得的溴化β-内酯的结构分析显示,立体化学与1937年最初指定的相反:顺式烯烃产生赤型内酯,反式烯烃产率苏式内酯。使用水性溶剂的PCM描述进行的B3LYP / 6-31 + G(d)计算证实了我们提出的机理的有效性,其中每种情况下形成的中间体均为α-内酯。环状溴物种不是中间体。通过不寻常的前端置换机制,直接从顺式烯烃通往顺式内酯的替代途径的自由能高出20 kJ mol(-1)。