一种新型α-甲醚基吡咯的合成

以乙酰乙酸苄酯(4)为原料, 经Knorr缩合制备了2，4-二甲基-3-丙酸甲酯基-5-羧酸苄酯基-1-氢吡咯 (2) 和2，4-二甲基-3-羧酸甲酯基-5-羧酸苄酯基-1-氢吡咯(3)。乙醚介质中，溴水氧化条件下，吡咯 (2) 发生自身缩合生成二吡咯甲烷 (7)，吡咯 (3)无反应发生。在Pb(OAC)₄氧化条件下，当其浓度为吡咯 (3)浓度的2倍时，在80 ℃，吡咯 (3) 完全转华。所得产物经HCl甲醇溶液回流，以82%的产率制备了新型2-甲氧基甲基-3-羧酸甲酯基-4-甲基-5-羧酸苄酯基-1氢吡咯 (1)。吡咯(1)、(2)、(3)及二吡咯(7)的结构用核磁、元素分析、质谱和红外等测试技术进行了表征。吡咯(1)的构建对进一步研究吡咯构效关系具有一定参考价值。

Synthesis of a Novel α-Methoxylmethyl Pyrrole

2,4-Dimethyl-3-(3-methoxy-3-oxopropyl)-5-benzylcarboxylate-1H-pyrrole(2) and 2,4-dimethyl-3-methoxymethyl-5-benzylcarboxylate-1H-pyrrole(3) were synthesized from benzyl ethylacetate(4) via the Knorr condensation reaction. In the ether solution of bromine, pyrrole (2) was converted to the corresponding dipyrromethane (7) through self-condensation, while no reaction happened to pyrrole(3). Under the 2 mol/L Pb(OAC)_4 oxidative condition, when it was twice the concentration of pyrrole (3), at 80 ℃, pyrrole(3) was completely consumed. After the subsequent refluxing in the methanol solution of hydrochloride acid, a novel 2-methoxymethyl-3-methylcarboxylate-4-methyl-5-benzylcarboxylate-1H-pyrrole(1) was synthesized in a yield of 82%. Pyrrole (1), pyrrole (2), pyrrole (3) and dipyrrolemethane (7) were characterized through NMR, elemental analysis, MS and IR. The construction of pyrrole (1) will be helpful for the further study of the structure-functionality relationship of pyrrole derivatives.