Diammonium Hydrogen Phosphate: An Efficient and Versatile Catalyst for the One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives in Aqueous Media.

Diammonium hydrogen phosphate was used as a mild, efficient, neutral, and cheap catalyst for the synthesis of various 4H-benzo[b]pyran derivatives via a one-pot, three-component condensation of aromatic aldehydes, active methylene compounds, and dimedone in aqueous media. [ABSTRACT FROM AUTHOR]