TRANSITION-METAL-CATALYZED α-ARYLATION OF ENOLATES

摘要

The last three decades have witnessed increasing efforts to develop highly efficient and selective tools for the catalyzed formation of carbon-carbon and car-bon-heteroatom bonds. Among the latter, outstanding results have been obtained in the field of soft, non-organometallic nucleophiles. The formation of carbon-oxygen, -nitrogen, -sulfur, -phosphorus, -boron, or -silicon bonds has become as widely used as the well-known Suzuki, Corriu-Kumada-Tamao, Stille, Negishi, Hiyama, and Sonogashira cross-coupling reactions. One of the major challenges is the α-arylation of soft carbon nucleophiles such as stabilized carbon enolates and related functional groups. Although α-arylated carboxylic acids (and keto derivatives) are prevalent in natural products (for example, lucuminic acid, welwistatin, and chloropeptin and vancomycin) and are important building blocks in a number of drugs (such as the anti-inflammatory agents Naproxen and Ibuprofen, the anesthetic Scopolamine, and p-malonylphenylalanine (Pmf, a potent phosphotyrosine mimetic), catalytic α-arylation of stabilized carbon enolates had, until recently, been described only rarely (Fig. 1).