Asymmetric Synthesis of 3,4-Disubstituted 2-(Trifluoromethyl)pyrrolidines through Rearrangement of Chiral 2-(2,2,2-Trifluoro-1-hydroxyethyl)azetidines
作者:Jeroen Dolfen、Esma Birsen Boydas、Veronique Van Speybroeck、Saron Catak、Kristof Van Hecke、Matthias D’hooghe
DOI:10.1021/acs.joc.7b01241
日期:2017.10.6
deployed as synthons for the diastereoselective formation of chiral 2-(2,2,2-trifluoro-1-hydroxyethyl)azetidines via trifluoromethylation through aldehyde modification followed by reductive removal of the β-lactam carbonyl moiety. Subsequent treatment of the (in situ) activated 2-trifluoroethylated azetidines with a variety of nitrogen, oxygen, sulfur, and fluorine nucleophiles afforded chiral 3,4-disubstituted
对映体4-甲酰基-β-内酰胺被用作合成子,通过醛修饰的三氟甲基化,然后还原性去除β-内酰胺羰基部分,非对映选择性地形成手性2-(2,2,2-三氟-1-羟乙基)氮杂环丁烷。随后用各种氮,氧,硫和氟亲核试剂处理(原位)活化的2-三氟乙基化氮杂环丁烷,可提供手性的3,4-二取代的2-(三氟甲基)吡咯烷,收率好至极好(45–99%)和高非对映选择性(dr> 99/ 1,1 H NMR)通过拦截双环叠氮鎓中间体而实现。此外,将代表性的吡咯烷类以选择性方式N,O-去苄基化,并用于进一步的合成精制以生产例如CF 3。-取代的2-oxa-4,7-二氮杂双环[3.3.0] octan-3-one系统。