DBU-Promoted Cascade Synthesis of Dihydrocoumarins from p -Quinone Methides and o -Hydroxy Aldimines

A facile synthesis of dihydrocoumarin derivatives has been successfully accessed with ortho-hydroxyphenyl-substituted para-quinone methides (p-QMs) and ortho-hydroxy aromatic aldimines. The reaction proceeds through a Michael addition followed by an intramolecular phenolysis sequence. This cascade strategy provides structurally diverse 4-aryl-3,4-dihydrocoumarins in good to excellent yields with excellent diastereoselectivity. Moreover, this versatile method exhibits significant promise for the synthesis of natural products and biologically relevant compounds that possess a substituted coumarin skeleton.