Enantioselective Synthesis of Aza-β-lactams via NHC-Catalyzed [2 + 2] Cycloaddition of Ketenes with Diazenedicarboxylates
作者:Xue-Liang Huang、Xiang-Yu Chen、Song Ye
DOI:10.1021/jo901656q
日期:2009.10.2
N-Heterocyclic carbenes were found to be efficient catalysts for the formal [2 + 2] cycloaddition of aryl(alkyl)ketenes and diazenedicarboxylates to give the corresponding aza-β-lactams in good yields with up to 91% ee. The N-substituent (carboxylate vs benzoyl) of diazenes played an important role to control the reaction modes (formal [2 + 2] vs [4 + 2] cycloaddtions).
发现N-杂环卡宾是有效的催化剂,用于芳基(烷基)烯酮和二氮烯二羧酸酯的正式[2 + 2]环加成反应,从而以高收率得到相应的氮杂-β-内酰胺,ee最高可达91%。二氮嗪的N-取代基(羧酸盐与苯甲酰基)在控制反应模式(正式[2 + 2]与[4 + 2]环加成反应)中起着重要作用。