Tetra-methyl ammonium hydroxide: An efficient and versatile catalyst for the one-pot synthesis of tetrahydrobenzo[b]pyran derivatives in aqueous media

Tetra-methyl ammonium hydroxide has been 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 in aqueous media. This method offers the advantages of proceeding, neutral and mild conditions, giving high to excellent yields of the products and simple work-up.