Synthesis of Enantioenriched Aza-Proline Derivatives through Gold(I)-Catalyzed Cyclization of Chiral α-Hydrazino Esters
作者:Sébastien Bouvet、Xavier Moreau、Vincent Coeffard、Christine Greck
DOI:10.1021/jo302320v
日期:2013.1.18
A selective gold(I)-catalyzed synthesis of chiral aza-proline derivatives has been developed by ring closure of enantioenriched α-hydrazino esters bearing an alkyne group. These are easily prepared through a synthetic strategy involving two key steps: organocatalyzed electrophilic amination of pent-4-ynal with dialkyl azodicarboxylate promoted by l-proline and functionalization of the triple bond by
通过带有炔基的对映体富集的α-肼基酯的闭环,已经开发了选择性金(I)催化的手性氮杂脯氨酸衍生物的合成。这些可以容易地通过涉及两个关键步骤的合成策略来制备:戊-1-酮与1-脯氨酸促进的偶氮二羧酸二烷基酯的有机催化亲电胺化和Sonogashira交叉偶联功能化三键。该策略允许使用Ph 3 PAuCl / AgBF 4作为催化体系,制备一系列经过环封闭的对映体富集的α-肼基酯。在这种情况下,5- exo - dig环化优于6- endo- dig并以良好的收率得到了氮杂脯氨酸衍生物和氮杂脯氨酸衍生物,而在立体异构中心没有差向异构。还研究了催化体系,肼保护基和炔烃取代对环化步骤的影响。