Clean chemical synthesis of 2-amino-chromenes in water catalyzed by nanostructured diphosphate Na2CaP2O7

A versatile, alternative and environmentally benign three-component strategy to the synthesis of a series of 2-amino-chromenes has been successfully performed in water, using nanostructured diphosphate Na2CaP2O7 (DIPH) as a basic catalyst. The products are obtained in high recoveries from the one-pot multi-component reaction procedure involving carbonyl compounds, malononitrile and 1-naphtol, resulting in a green synthetic protocol with high atom economy. The catalyst is waste-free, easily prepared, and efficiently re-used. The prepared 2-amino-chromenes, in presence of acetic anhydride, have been easily converted to benzo(a)anthracene derivatives.