C5-Disubstituted Meldrum's Acid Derivatives as Platform for the Organocatalytic Synthesis of C3-Alkylated Dihydrocoumarins

C5-disubstituted Meldrum's acid precursors were shown to be a useful platform for the synthesis of an array of 3-alkylated dihydrocoumarins with up to 93:7 er, thanks to an enantioselective domino cyclization-decarboxylative-protonation reaction triggered by an unprecedented benzhydryl-derived cupreine organocatalyst. This cyclization sequence was extended to an emerging organocatalytic decarboxylative-chlorination reaction in the presence of trichloroquinolinone and by means of a bifunctional cinchona derived Bronsted base which gave rise to the formation of dihydrocoumarins (up to 79:21 er) with a tertiary chlorinated stereocenter.