Pathway for the stereocontrolled Z and E production of alpha,alpha-difluorine-substituted phenyl butenoates.
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.
Ghattas
Wadih
W
BioSciences, FRE-CNRS 3005, Faculté des Sciences et Techniques, Université Paul Cézanne Aix-Marseille III, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France.
Hess
Corinna R
CR
Iacazio
Gilles
G
Hardré
Renaud
R
Klinman
Judith P
JP
Réglier
Marius
M
D000114:Acetylene / Q000031:analogs & derivatives / Q000737:chemistry; D002087:Butyrates / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D013237:Stereoisomerism
D002087:Butyrates; C044736:phenylacetylene; D005461:Fluorine; D000114:Acetylene