Room temperature preparation of α-chloro-β,β-difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes

α-Chloro-β,β-difluorovinylzinc reagent [CF2CClZnCl] was generated in 91% yield by the metallation of a THF solution of commercially available HCFC-133a (CF3CH2Cl) and zinc chloride at 15-20 °C using LDA as base. The corresponding reaction with Halothane™ (CF3CHClBr) produced a poor yield of CF2CClZnCl. The palladium catalyzed coupling reaction of the CF2CClZnCl with aryl iodides under mild reaction conditions produced α-chloro-β,β-difluorostyrenes in 64-90% isolated yields. The stability of the intermediate CF2CClLi and the nature of the zinc reagents are discussed.