Tetraarylphosphonium Halides as Arylating Reagents in Pd-Catalyzed Heck and Cross-Coupling Reactions

摘要

Transition-metal-catalyzed olefination and cross-coupling reactions have become one of the most powerful tools in organic synthesis.While aryl,alkenyl,alkynyl,and,more recently,alkyl halides are typically employed as coupling reagents,a variety of different types of pseudohalide species have been also investigated as useful electrophiles.Among these,representative recent examples are carboxylic acids,acid anhydrides,aryl esters,sulfonates,151 phosphonic acids,sulfonium ions,and ammonium salts.Although metal-mediated C-P bond cleavage of organophosphorus species was previously investigated,the use of such compounds in cross-coupling reactions has been relatively underdeveloped.