New Asymmetric Approach to Natural Pyrrolizidines: Synthesis of (+)-Amphorogynine A, (+)-Amphorogynine D, and (+)-Retronecine
作者:Caroline Roche、Katarína Kadlečíková、Amaël Veyron、Philippe Delair、Christian Philouze、Andrew E. Greene、David Flot、Manfred Burghammer
DOI:10.1021/jo050983o
日期:2005.10.1
Three natural pyrrolizidines, (+)-amphorogynines A and D and (+)-retronecine, have been prepared from a common lactam intermediate. This central compound, in turn, was synthesized in diastereomerically enriched form through a highly selective [2 + 2]-cycloaddition of dichloroketene with a chiral enol ether, followed by Beckmann ring expansion and reduction. Subsequent stereocenters were then cleanly
从普通的内酰胺中间体制备了三种天然的吡咯烷核苷,(+)-两性氨基酸A和D和(+)-维甲酸。反过来,通过二氯乙烯与手性烯醇醚的高选择性[2 + 2]-环加成反应,然后通过Beckmann环扩大和还原反应,以非对映异构体富集的形式合成该中心化合物。然后通过内部感应将后面的立体中心干净地引入。