A Four-Component Cascade C-H Functionalization/Cyclization/Nucleophilic Substitution Reaction To Construct α-Functionalized Tetrahydroquinolines by the Strategy of in Situ Directing Group Formation

A four-component cascade C-H functionalization/cyclization/nucleophilic substitution reactions of anilines, carboxylic anhydrides, propenol, and alkohols have been developed by a strategy of in situ directing group formation, affording an efficient and convenient synthesis of alpha-alkoxyl tetrahydroquinolines from basic starting materials. A plausible mechanism involving rhodium(III) catalytic C-H functionalization and double nucleophilic attacks is proposed. The nudeophilicity order of some alcohols is also obtained for the cascade reaction.