Studies On Friedel-Crafts Alkylation-Esterification Cascade Reactions Catalyzed By N-Heterocyclic Carbenes

This thesis is composed of three parts:(1) N-Heterocyclic carbenes are well known as organocatalysts which have been applied to organic synthesis. The progresses of N-heterocyclic carbenes as organo-catalysts involving benzoin condensations, Stetter reactions, nucleophilic substitution reactions, hydroacylation reactions of electron-neutral bonds and domino reactions of a3to d3umpolung were reviewed.(2) We have developed a Friedel-Crafts alkylation-esterification reaction of α-bromo-α,β-unsaturated aldehydes with2-naphthol derivatives catalyzed by N-Heterocyclic carbenes. It provides a highly efficient, general route to synthesis of dihydropyran-2-one derivatives. The advantages of this cascade reaction are excellent yields (up to97%), mild conditions and short working time (1h).(3) A series of novel functionalized piperidine derivatives were easily synthe-sized by three-multicomponent tandem aza-Michael-Aldol cascade reactions of α,β-unsaturated ketones with substituted sulfonamide in the presence of DBU. With the optimized reaction conditions, the desired products were obtained with high diastereoselectivity (up to20:1) and good yields (up to84%).