Synthesis of 3-Substituted Dihydro-1-phenylamino-1H-pyrrolo[1,2-a]imidazole-2,5(3H,6H)-diones fromα-Amino Acid Phenylhydrazides and Levulinic Acid
作者:Giancarlo Verardo、Paola Geatti、Marcello Merli、Elena E. Castellarin
DOI:10.1002/ejoc.200400112
日期:2004.7
acid to produce the imidazolidin-4-one intermediates 4, which undergo a second ring closure to afford the dihydro-1H-pyrrolo[1,2-a]imidazole-2,5-dione derivatives 5. It has been established that the solvent polarity has a great influence on the rate of the second condensation reaction, but not on the first. A mechanism, supported by experimental evidence, has been proposed to explain how the imidazolidin-4-one
α-氨基酸苯酰肼 1 容易与乙酰丙酸反应生成 imidazolidin-4-one 中间体 4,中间体 4 进行第二次闭环得到二氢-1H-吡咯并[1,2-a]咪唑-2,5-二酮衍生物 5. 已经确定溶剂极性对第二次缩合反应的速率有很大影响,但对第一次没有影响。已经提出了一种由实验证据支持的机制来解释作为两种非对映异构体混合物获得的 imidazolidin-4-one 中间体 4 如何产生双环衍生物 5 的单一异构体;这些化合物的绝对立体化学已通过 X 射线晶体学分析确定。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)