A Novel and Convenient Protocol for Synthesis of α-Haloacrylates
摘要:
A.novel and convenient protocol for synthesis of alpha-haloacrylates starting from phosphonium ylide and aldedyde or alcohol was described. Halodimethylsulfonium halide was used for the first time in halogenation of phosphonium ylide. Good yield as well as a high Z/E ratio were shown in representative cases, and an umpolung dimethyl sulfide-ylide species might be involved as an intermediate.
Bis(2,2,2-trifluoroethyl)bromophosphonoacetate, a Novel HWE Reagent for the Preparation of (<i>E</i>)-α-Bromoacrylates: A General and Stereoselective Method for the Synthesis of Trisubstituted Alkenes
作者:Keiko Tago、Hiroshi Kogen
DOI:10.1021/ol006074x
日期:2000.6.1
A novel reagent, methyl bis(2,2,2-trifluoroethoxy)bromophosphonoacetate (3a), was designed and prepared in order to efficiently synthesize (E)-alpha-bromoacrylates, which are useful precursors for various C-C bond formations. Honer-Wadsworth-Emmons (HWE) reaction of various aldehydes with 3a in the presence of t-BuOK and 18-C-6 gave the corresponding (E)-alpha-bromoacrylate derivatives with high stereoselectivity