Solvent-free synthesis of chromene derivatives

We report the reaction between dialkyl acetylenedicarboxylates and enolic systems such as 4-hydroxy coumarin, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclohexanedione and 1,3-cyclopentanedione in the presence of isoquinoline under solvent-free conditions which leads to chromene derivatives.