Efficient Synthesis of Novel Coumarin‐3‐carboxamides (=2‐Oxo‐2H‐1‐benzopyran‐3‐carboxamides) Containing Lipophilic Spacers

Abstract

AbstractThe novel coumarin‐3‐carboxamides (=2‐oxo‐2H‐1‐benzopyran‐3‐carboxamides) 5a–5g containing lipophilic spacers were synthesized through the Ugi‐four‐component reaction (Scheme 1). The reactions of aromatic aldehydes 1, 4,4′‐oxybis[benzenamine] or 4,4′‐methylenebis[benzenamine] as diamine 2, coumarin‐3‐carboxylic acid (=2‐oxo‐2H‐benzopyran‐3‐carboxylic acid; 3), and alkyl isocyanides 4 lead to the desired substituted coumarin‐3‐carboxamides 5a–5g at room temperature with high bond‐forming efficiency. These novel coumarin derivatives exhibit brilliant fluorescence at 544 nm in CHCl3.