Dearomatizative and Decarboxylative Reaction Cascade in the Aminocatalytic Synthesis of 3,4-Dihydrocoumarins

Within the performed study, a dearomatizative and decarboxylative reaction cascade for the synthesis of biologically relevant 3,4-dihydrocoumarins has been developed. It utilizes 2-alkyl-3-furfural derivatives that under aminocatalytic conditions are transformed into dienamine-like intermediates in a process that involves dearomatization of the furan ring. Subsequent [4+2]-cycloaddition with coumarin-3-carboxylic acids proceeds with rearomatization of the furan moiety. In the last step of the cascade, the aminocatalyst is released via decarboxylative deamination to give target 3,4-dihydrocoumarins with excellent enantio- and diastereocontrol.