Application of the photocyclization reaction of 1,2-cyclopenta-fused pyridinium perchlorate to formal total syntheses of (−)-cephalotaxine
作者:Zhiming Zhao、Patrick S. Mariano
DOI:10.1016/j.tet.2006.05.045
日期:2006.7
Two strategies for the formal total synthesis of (−)-cephalotaxine, based on pyridinium salt photochemistry, are described. The routes begin with photocyclization reaction of 1,2-cyclopenta-fused pyridinium perchlorate. This process efficiently and regioselectively produces a tricyclic aziridine, which undergoes sequential aziridine ring opening and enzymatic desymmetrization to generate enantio-enriched
描述了两种基于吡啶盐光化学法正式合成(-)-头孢他辛的策略。路线从1,2-环戊基稠合的高氯酸吡啶鎓的光环化反应开始。该过程有效且区域选择性地产生三环氮丙啶,其依次进行氮丙啶开环和酶促脱对称作用以产生对映体富集的中间体,该中间体含有在头孢他辛中发现的螺环D,E-环系统。这些物质是森(Mori),蒂埃泽(Tietze)和吉田(Yoshida)在(-)-头孢他辛的早期合成中使用的晚期关键中间体的前体。