Asymmetric Synthesis of <i>gem</i>-Difluoromethylenated Dihydroxypyrrolizidines and Indolizidines
作者:Watcharaporn Thaharn、Teerawut Bootwicha、Darunee Soorukram、Chutima Kuhakarn、Samran Prabpai、Palangpon Kongsaeree、Patoomratana Tuchinda、Vichai Reutrakul、Manat Pohmakotr
DOI:10.1021/jo301327s
日期:2012.10.5
An asymmetric synthesis of gem-difluoromethylenated dihydroxypyrrolizidines and indolizidines is described. The fluoride-catalyzed nucleophilic addition of PhSCF2SiMe3 (1) to chiral imides was achieved in satisfactory yields to provide mixtures of syn- and anti-isomers 6–9 with moderate to good diastereoselectivities. Reductive cleavage of the phenylsulfanyl group followed by intramolecular radical
描述了宝石-二氟亚甲基化的二羟基吡咯烷核苷和吲哚并核苷的不对称合成。氟化物催化的亲核加成PhSCF的2森达3(1)手性酰亚胺在令人满意的产率实现,以提供的混合物顺式-和反-异构体6 - 9与中度至良好非对映选择性。的苯硫基团的还原裂解,随后通过分子内自由基环化顺式-异构体6 - 9发生下回流条件,得到相应的宝石-difluoromethylenated 1-氮杂双环化合物10 - 13在中等产率作为一个可分离混合物的顺式-和反式-异构体。所述顺式化合物的异构体10和12以及反式- 13被容易地转化为宝石-difluoromethylenated dihydroxypyrrolizidines 20和27和吲哚里28分别由羟基和有机金属加成,接着通过氢的还原裂解。