Vinylic halides coupling

There are several cases of applications of vinylboron-vinyl halide coupling reactions in synthesis of targeted natural products or related molecules225,233,234 the synthesis of (5 S,6i )-5,6-DiHETE methyl ester (where DiHETE = Dihydroxy-7,9,11,14-eicosatetra-enoic acid) is based on such a reaction for the formation of its trienic portion (equation 122)233. 

Alkyne to vinyl halide coupling reactions have been used extensively in synthesis, due to the popularity of enediyne antitumour antibiotics280. An example is given in equation 144. 

In this sense Organ and coworkers [80] have developed intriguing syntheses of polysubstituted olefins based upon consecutive intermolecular reactions such as allylic and allylic-vinylic halide coupling sequences. Therefore, l-acetoxy-4-chloro but-2-ene can be readily submitted as a template for Pd-catalyzed allylic substitutions with two different carbon or nitrogen nucleophiles, leading to unsymmetrically substituted butene derivatives 66-70 in good yields (Scheme 22). Mechanistically, the chloro substituent is replaced... 

R X is most often a vinyl halide or aryl halide. With vinyl halides, coupling is stereospecific. 

In 1991, a new C-N-C bond formation reaction using a nitrogenation-transmetalation process was described. Ketones and aryl or vinyl halides couple to give divinyl or arylvinyl amines in the presence of the titanium isocyanate complex [3THF MgaClaO TiNCO] and a palladium catalyst, via transmetallation of the titano imine complex with aryl or vinyl palladium bromide. Moderate to good yields of the desired products were observed (Scheme 2.176). 

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