Butatriene formation via CuBr-induced self coupling of an α-bromo vinyl zinc reagent: synthesis and X-ray structure of Z-1,1,1,6,6,6-hexafluoro-2,5-diphenylhexa-2,3,4-triene

Abstract

Title cumulenes 2a and 2b were prepared by reaction of CF₃(Ph)CC(Br)ZnX [X = Br, CF₃(Ph)CCBr–]1 with CuBr, or by oxidative coupling of 1 with FeCl₃ to form 2a,b and [CF₃(Ph)CCBr–]₂3, which can be dehalogenated with zinc to afford 2a,b; the cumulene isomers are readily separated by silica-gel chromatography, and may be prepared in good yield on a multi-gram scale.