作者:Takeo Kawabata、Seiji Matsuda、Shimpei Kawakami、Daiki Monguchi、Katsuhiko Moriyama
DOI:10.1021/ja0670761
日期:2006.12.1
potassium amide bases in DMF, cyclization proceeds with retention of configuration, while inversion of configuration was observed with lithium amide bases in THF. Chirality of the parent amino acids was preserved during enolate formation and cyclization to give aza-cyclic amino acids in up to 98% ee with retention of configuration or inversion of configuration, depending on the reaction conditions. Thus, both
已开发出 N-Boc-N-ω-溴烷基-α-氨基酸衍生物的对映发散不对称环化。在 DMF 中使用氨基钾碱时,环化在构型保留的情况下进行,而在 THF 中使用氨基化锂碱时观察到构型反转。在烯醇化物形成和环化过程中保留了母体氨基酸的手性,以产生高达 98% ee 的氮杂环氨基酸,并保留构型或反转构型,这取决于反应条件。因此,具有四取代立体中心的环状氨基酸的两种对映异构体均以高对映异构纯度从容易获得的l-α-氨基酸制备。该协议也适用于α-氨基酸衍生物的螺环化和分子内共轭添加,