An efficient synthesis of 3-arylmethyl-7,8-dihydro-6H-chromene-2,5-diones from Baylis-Hillman adduct acetates under solvent-free conditions

A simple, efficient synthesis of 3-arylmethyl-7,8-dihydro-6H-chromene-2,5-dione 4 from Baylis-Hillman adduct acetates derived from aromatic aldehydes and cyclohexane-1,3-diones under solvent-free conditions is described. Interestingly, when Baylis-Hillman adducts derived from aliphatic aldehydes were tested under the similar conditions, the unexpected stereoisomers 5 and 6 were obtained in moderate yields. A plausible mechanism for the formation of 4-6 is proposed.