Enantioselective Construction of Bridged Multicyclic Skeletons: Intermolecular [2+2+2] Cycloaddition/Intramolecular Diels-Alder Reaction Cascade

Recent advances towards a development of novel transition-metal-catalyzed enantioselective [2+2+2] cycloadditions for the synthesis of axially chiral biaryls are reviewed. A number of efficient enantioselective biaryl syntheses were accomplished by chiral cobalt(I), iridium(I), and rhodium(I) complex catalyzed [2+2+2] cycloadditions. Furthermore, the enantioselective synthesis of axially chiral biaryls possessing non-biaryl axial chirality was also developed by using chiral rhodium(I) complexes as catalysts.