Synthesis of 2-substituted cyclohexene derivatives through cross-coupling reactions via π-allylmetal intermediate using N-heterocyclic carbenes (NHCs) as ligands

Palladium- or nickel-catalyzed cross-coupling reactions of 2-substituted cyclohexenes, which are generally less reactive than those having no substituent at the C2 position, with organotin reagents (Migita-Kosugi-Stille coupling) or with Grigard reagents (Kumada-Tamao-Corriu coupling) using a NHC as a ligand was investigated. It was found that NHCs are effective as ligands for these reactions, giving the corresponding cross-coupling products in good yields.