Metal groups vinyl halide/triflates

C-C bond formation via transition-metal-catalysed cross coupling of -activated enols has been reviewed (97 references) while less reactive than systems involving halide or triflate leaving groups, vinyl phosphates have significant advantages in terms of cost, stability, and low toxicity... 

Halide and triflate leaving groups are also involved with palladium catalysis in the most general of all these reactions with vinyl electrophiles. These use a main group rather than transition metal, chiefly boron or tin, in stoichiometric amounts to mark one molecule as nucleophilic and then... 

The triflate (trifluoromethanesul-fonate) anion, CF3SO3, or TfO-is an excellent, non-basic leaving group. It Is often used as an oxygen-based alternative to halides, and metals will insert into the C-OSO2CF3 bond. Triflates, particularly aryl and vinyl triflates, can be made conveniently with Comins reagent. 

The RX substrate must not contain a flexible P C-H bond so that the metal-alkyl species resulting from its oxidative addition be prevented from undergoing p-elimi-nation before the insertion step (which would result in an overall dehydrohalogena-tion of RX). Thus, the R group must be a vinyl, aryl (the p position is not flexible in these groups) or benzyl radical. The reaction is carried out upon heating RX (organic halide or triflate) with the alkene, a catalytic amount of Pd and an excess of tertiary amine in acetonitrile. 

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