A Convenient Preparation of Diastereomerically Pure, Diversely Substituted Piperazine-2,5-diones from N-Protected α-Amino Acids
作者:Mikhail Krasavin、Mikhail Nikulnikov、Alexei Shumsky
DOI:10.1055/s-0029-1218829
日期:2010.8
ected α-amino acids, aldehydes, amines and tert-butyl isocyanide, after tert-butoxycarbonyl deprotection, undergo efficient microwave-assisted cyclization in acetic acid to give diastereomerically pure, racemic piperazine-2,5-diones. The formation of a single diastereomer is rationalized via an enolization equilibration process in acetic acid at high temperature which enriches the product mixture
的各种的Ugi反应的产物ñ -叔丁氧羰基保护的α氨基酸,醛,胺和叔丁基胩,之后叔丁氧羰基脱保护,进行在乙酸高效微波辅助环化,得到对映异构纯的,外消旋哌嗪-2,5-二酮。通过在乙酸中在高温下的烯醇平衡过程合理化单一非对映异构体的形成,这使产物混合物富含更稳定的非对映异构体。产品的相对立体化学已通过NOESY实验证实,并且与分子力学计算一致。 哌嗪-2,5-二酮-Ugi多组分反应-Ugi后修饰-微波辅助-烯化