Alkyl halides cobalt-catalyzed Heck reactions

Fig. 54 Cobalt-catalyzed Heck reactions of alkyl halides and styrenes...

Cobalt-catalyzed Heck-type Reaction of Alkyl Halides with Styrenes... 

As a Generator of Alkyl Radicals from Alkyl Halides in the Presence of Cobalt Catalysts. A conceptually novel use of Me3SiCH2MgCl recently emerged in cobalt-catalyzed Heck-type transformations. The palladium-catalyzed Heck reaction always etT5)loys aryl- or alkenyl halides. In eontrast, alkyl halides are not available for use as starting material, due to predominant 0-hydride elimination from the corresponding alkylpalladium... 

A method complementary to the palladium-catalyzed reaction has been reported. A cobalt-phosphine complex catalyzes a Heck-type reaction of alkyl halides with styrenes in the presence of Me3SiCH2MgCl [174]. Trimethylsilylmethylmag-nesium chloride was added to a mixture of styrene and bromocyclohexane in ether in the presence of a catalytic amount of CoCl2(dpph) at O C. Heating the reaction mixture under reflux (35°C) provided 163a in 91% yield (Scheme 3.158). 

Affo, W., Ohmiya, H., Fujioka, T. et al. (2006) Cobalt-catalyzed trimethylsilylmethylmagnesium-promoted radical alkenylation of alkyl halides a complement to the Heck reaction. J. Am. Chem. Soc., 128, 8068-77. 

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