Et2AlCl Promoted Coupling Reactions of 4-Hydroxy-2-pyrone or 4-Hydroxycoumarine with Aldehydes: Synthesis of Methylenebis-(4-hydroxy-2-pyrone) or Methylenebis-(4-hydroxycoumarine) Derivatives
Methylenebis(4-hydroxy-2-pyrone) or methylenebis(4-hydroxy-coumarine) derivatives (5) have been synthesized from 4-hydroxy-2-pyrones (6) and (8) or 4-hydroxycoumarine (10) with aldehydes (4) in the presence of diethylaluminum chloride.