Domino Decarboxylative Arylation and C-O Selective Bond Formation toward Chromeno[2,3-b]pyridine-2-one Skeletons

One-pot reaction of 3-vinylchromones, aromatic aldehydes, and ammonium acetate: an efficient approach to highly functionalized 1,6-dihydropyridine derivatives

In this work, we present an efficient strategy for the straightforward synthesis of functionalized 1,6-dihydropyridine derivatives via a three-component reaction of 3-vinylchromones, aromatic aldehydes, and ammonium acetate. A tandem procedure including in situ NH aldimine formation/Michael-type addition/opening of the pyrone ring/isomerization/6π-electrocyclization/[1,5]-H shift allows rapid access to a series of dihydropyridines bearing an ortho-hydroxybenzoyl and a benzoyl scaffold in good yields. Readily available precursors, simple heating conditions, and operational simplicity are some highlighted advantages of this transformation.

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

A pseudo-three-component annulation reaction of substituted 2-amino-4H-chromen-4-ones with aromatic aldehydes promoted by DBU was investigated to access polysubstituted 5H-chromeno[2,3-b]pyridines. This reaction included a sequential intermolecular nucleophilic addition/Michael cyclization/intramolecular epoxidation/ring opening/aromatization sequence, which possessed excellent step and atom economy in a single operation for generating 3-hydroxy-5H-chromeno[2,3-b]pyridines from readily available substrates.