[3+3] Annulation Reaction of 2‐Amino‐4H‐chromen‐4‐ones with Cinnamaldehydes or Aromatic Aldehydes and Ethanal in One Pot: Access to 2‐Aryl‐5H‐Chromeno[2,3‐b]pyridin‐5‐ones

Abstract

A formal [3 + 3] cascade annulation strategy for the synthesis of 2-arylchromeno[2,3-b]pyridinones has been developed using 2-aminochromones and substituted cinnamaldehydes or aromatic aldehydes and ethanal as the substrates. The strategy supplies a novel and atom-economical method of accessing a broad range of chromeno[2,3-b]pyridine derivatives in good yields with good functional-group tolerance. The method highlights the inherent practicality of this synthetic transformation.

Synthesis of 2H-Chromeno[2,3-b]tetrahydropyridine Frameworks through Cs2CO3-Promoted Annulation of 2-Amino-4H-chromen-4-ones and 4-Benzylideneoxazol-5(4H)-ones

“…Generally, 2-aminochromones as the 1,3-bis-nucleophilic enamine skeleton served as three-atom synthons when the pyran ring participated in the [3+3] cyclization to furnish pyridine derivatives . Simultaneously, we also explored 2-aminochromones as a key substrate in the annulation reactions with apt partners for the synthesis of diversely substituted 5 H -chromeno­[2,3- b ]­pyridines . Additionally, a dihydropyridine or tetrahydropyridine scaffold is a privileged structure in drug discovery and development .…”