A Rapid and Highly Effectual Protocol for the Synthesis of Bis-coumarins using Triethylaminium-N-sulfonic Acid Tetrachloroaluminate under Solvent-Free Conditions

In this work, a rapid and highly effectual protocol for the synthesis of       bis-coumarins has been developed. The one-pot quasi three-component reaction of aromatic aldehydes (1 eq.) with 4-hydroxycoumarin (2 eq.) in the presence of catalytic amount of protic acidic ionic liquid triethylaminium-N-sulfonic acid tetrachloroaluminate (TSAT) under solvent-free conditions afforded the mentioned compounds in high yields and short reaction times.