title: Pathway for the stereocontrolled Z and E production of alpha,alpha-difluorine-substituted phenyl butenoates.
abstract: An efficient preparation of pure ethyl Z- and E-alpha,alpha-difluoro-4-phenyl-3-butenoate 1a and 1b together with the corresponding acids 2a and 2b is described. The procedures involve stereocontrolled additions of *CF2CO2Et to phenylacetylene or beta-bromostyrene. Compound 1a is easily obtained by addition of *CF2CO2Et to phenylacetylene via a mechanism where the stereochemistry is controlled by an electron-transfer process to produce predominantly the Z vinyl anion. The product 1b is obtained by *CF2CO2Et addition-elimination to Z- or E-beta-bromostyrenes via a mechanism where the stereochemistry is controlled by steric factors in the conformational equilibration of the intermediates.
authors.affiliation: BioSciences, FRE-CNRS 3005, Faculté des Sciences et Techniques, Université Paul Cézanne Aix-Marseille III, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France.
authors.forename: Wadih
authors.initials: W
authors.lastname: Ghattas
authors.forename: Corinna R
authors.initials: CR
authors.lastname: Hess
authors.forename: Gilles
authors.initials: G
authors.lastname: Iacazio
authors.forename: Renaud
authors.initials: R
authors.lastname: Hardré
authors.forename: Judith P
authors.initials: JP
authors.lastname: Klinman
authors.forename: Marius
authors.initials: M
authors.lastname: Réglier
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives / Q000737:chemistry; D002087:Butyrates / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D002087:Butyrates; C044736:phenylacetylene; D005461:Fluorine; D000114:Acetylene