Aryl-alkenyl cross-coupling scope

The Suzuki Coupling, which is the palladium-catalysed cross coupling between organoboronic acid and halides. Recent catalyst and methods developments have broadened the possible applications enormously, so that the scope of the reaction partners is not restricted to aryls, but includes alkyls, alkenyls and alkynyls. Potassium trifluoroborates and organoboranes or boronate esters may be used in place of boronic acids. Some pseudohalides (for example triflates) may also be used as coupling partners. 

The insight that zinc ester enolates can be prepared prior to the addition of the electrophile has largely expanded the scope of the Reformatsky reaction.1-3 Substrates such as azomethines that quaternize in the presence of a-halo-esters do react without incident under these two-step conditions.23 The same holds true for acyl halides which readily decompose on exposure to zinc dust, but react properly with preformed zinc ester enolates in the presence of catalytic amounts of Pd(0) complexes.24 Alkylations of Reformatsky reagents are usually difficult to achieve and proceed only with the most reactive agents such as methyl iodide or benzyl halides.25 However, zinc ester enolates can be cross-coupled with aryl- and alkenyl halides or -triflates, respectively, in the presence of transition metal catalysts in a Negishi-type reaction.26 Table 14.2 compiles a few selected examples of Reformatsky reactions with electrophiles other than aldehydes or ketones.27... 

Tamao, K., Sumitani, K., Kiso, Y., Zembayashi, M., Fujioka, A., Kodama, S., Nakajima, I., Minato, A., Kumada, M. Nickel-phosphine complex-catalyzed Grignard coupling. I. Cross-coupling of alkyl, aryl, and alkenyl Grignard reagents with aryl and alkenyl halides general scope and limitations. Bull. Chem. Soc. Jpn. 1976, 49, 1958-1969. 

Ni/PCys can catalyse cross-couplings of aryl cyanides with atyl or alkenyl boronic esters in the presence of KOtBu as base and CuFa as additive. The reaction exhibits a wide substrate scope and gives moderate to good product yields (Scheme 14.42). ° ... 

The Suzuki-Miyaura reaction involves the palladium-catalyzed cross-coupling between organoboron compounds and halides. In most cases, aryl halides are used as electrophiles, but recent developments have broadened the scope and alkyl, alkenyl, and alkynyl halides can be successfully used as reaction partners. Among C—C coupling reactions, Suzuki-Miyaura reaction has become one of the most appealing because the reactants are air stable, nontoxic and tolerant of a variety of functional groups. 

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