Triflates vinyl halide reagent

Vinylic copper reagents react with CICN to give vinyl cyanides, though BrCN and ICN give the vinylic halide instead." Vinylic cyanides have also been prepared by the reaction between vinylic lithium compounds and phenyl cyanate PhOCN." Alkyl cyanides (RCN) have been prepared, in varying yields, by treatment of sodium trialkylcyanoborates with NaCN and lead tetraacetate." Vinyl bromides reacted with KCN, in the presence of a nickel complex and zinc metal to give the vinyl nitrile. Vinyl triflates react with LiCN, in the presence of a palladium catalyst, to give the vinyl nitrile." ... 

Organozinc reagents, including the Reformatsky reagents, are extensively used in transition metal catalysed coupling reactions with aryl halides or triflates, vinyl halides, and allylic halides or acetates, as reviewed by Erdik156. Nickel and palladium complexes are... 

Ligand. Used for Pd-catalyzed reactions of aryl and vinyl halides and triflates. Also for Kumuda coupling reactions. See Dppe for a similar reagent. 

While die above reactions represent only a small fraction of die reactions known for palladium, they form the basis of a powerful methodology for building carbon structures. Several variations have been developed which utilize certain types of reactants and give particular types of products. All diese variations, however, contain a common theme. In each case an electron-deficient reagent (e.g., a vinyl halide or aromatic triflate) reacts with an election-rich reagent (e.g., an alkene, an organoborane, or an organotin) witii the formation of a new carbon-carbon bond. In that sense diese reactions are related to die reactions between carbon nucleophiles and carbon electrophiles discussed previously in diis chapter. They are quite different, however, because diey proceed only in the presence of Pd(0). In fact they proceed only in die coordination sphere of Pd(0). The ability of Pd(0) to catalyze diese reactions is nearly unique We will now examine some of die more common processes. 

Coupling o( organotin reagents (and Pd catalyst) with atyl or vinyl halides or triflates, acyl chlorides or iMyl acetates. 

In some cases, vinyl halides can be coupled. An aryl Grignard reagent was coupled to a vinyl iodide in the presence of an iron catalyst.Butylmag-nesium chloride was coupled to vinyl triflates with Fe(acac)3. ° The palladium-catalyzed coupling of arylmagnesium halides and vinyl bromides has also been reported. ... 

The Stille Coupling (Section 24.5C) The Stille coupling is the palladium-catalyzed reaction of a vinyl tin reagent with an organic halide or triflate.The mechanism involves oxidative addition of the organic halide/triflate, transmetallation of the vinyl group on Sn to Pd, and reductive elimination to form the new C—C bond. 

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