Enantioselective Synthesis of Dihydrocoumarins <i>via</i> N‐Heterocyclic Carbene‐Catalyzed Cycloaddition of Ketenes and <i>o</i>‐Quinone Methides

Abstract

Abstract Chiral N‐heterocyclic carbenes were found to be efficient catalysts for the formal [4+2] cycloaddition reaction of alky(aryl)ketenes and o ‐quinone methides to give the corresponding 3,3,4‐trisubstituted 3,4‐dihydrocoumarins in good yields with good diastereoselectivities and excellent enantioselectivities.