L-proline catalyzed synthesis of naphthopyranopyrimidines via multicomponent reaction

A green and efficient one pot, three component protocol for synthesis of naphthopyranopyrimidines by cyclocondensation of β-naphthol, aldehyde, and 6-amino-1,3-dimethyluracil using L-proline as a beneficial catalyst with high catalytic activity under solvent-free conditions at 100 °C is described. In this study, several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were rapidly converted to the corresponding naphthopyranopyrimidine derivatives in good to excellent yields. The present approach offers several advantages such as short reaction times, simple work-up, excellent yields, non-toxicity of the catalyst, and solvent-free conditions.To the best of our knowledge, this is the first report on the synthesis of naphthopyranopyrimidine derivatives using L-proline as a catalyst under solvent-free conditions. The catalysts can be recovered for the subsequent reactions and reused without any loss of efficiency.