Piperidine-Mediated [3 + 3] Cyclization of 2-Amino-4H-chromen-4-ones and 2-Benzylidenemalononitriles: To Access 2-Aminochromeno[2,3-b]pyridine Derivatives

Abstract

Piperidine-mediated [3 + 3] cyclization of 2-amino-4H-chromen-4-ones and substituted 2-benzylidenemalononitriles was developed for the synthesis of 2-amino-4-aryl-5H-chromeno­[2,3-b]­pyridin-5-one derivatives. This novel transformation provides a highly efficient and facile route to functionalized 5H-chromeno­[2,3-b]­pyridines from readily available substrates under mild reaction conditions.

Synthesis of Chromeno[2,3-d]pyrimidin-5-one Derivatives from 1,3,5-Triazinanes via Two Different Reaction Pathways

“…According to the literature, − possible mechanisms for the formation of 3 and 5 are proposed as shown in Scheme . Under In­(OTf) 3 -catalyzed conditions, 1,3,5-triazinane could be readily disconnected into three units of formaldimine, which further react with trace amount of water in solvent to afford amine and formaldehyde (eq a).…”

DBU-Mediated Domino Annulation Reaction of 2-Amino-4H-chromen-4-ones and Aromatic Aldehydes for Synthesis of Polysubstituted 3-Hydroxy-5H-chromeno[2,3-b]pyridinones

“…More recently, Yerrabelly et al also reported an access to chromeno­[2,3- b ]­pyridine derivatives via CuI/Cu­(OSO 2 CF 3 ) 2 -catalyzed [3 + 3] annulation reaction of 2-aminochromones with similar propargylic partners . 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 …”

DABCO-Promoted Cyclization of 2-Amino-4H-chromen-4-ones with 2,6-Dibenzylidenecyclohexan-1-ones for the Synthesis of Chromeno[2,3-b]tetrahydroquinoline

“…Recently, we performed many research projects on accessible 2-aminochromones as a key substrate for construction of diversely fused chromone systems . Owing to the diverse bioactivities of chromeno­[2,3- b ]­tetrahydro­quinolines, the development of efficiently synthetic methodologies for chromeno­[2,3- b ]­tetrahydro­quinoline derivatives continues to be a highly active area in organic synthesis.…”

“…According to our previous reports for the base-promoted cyclization of 2-amino-4 H -chromen-4-ones and appropriate substrates, the reaction of an equivalent amount of 2-amino-4 H -chromen-4-one ( 1a ) and 2,6-di­(4-methyl­benzylidene)­cyclohexan-1-one ( 2a ) was carried out in DMF at 120 °C for 24 h in the presence of triethylamine as a basic promoter under air. The reaction proceeded to give product 3a in trace quantity even after 24 h at 120 °C (Table , entry 1).…”