Sanchez L.M.,Research Center sarrollo En Ciencias Aplicadas Dr Jj Ronco Cindeca |
Sathicq A.G.,Research Center sarrollo En Ciencias Aplicadas Dr Jj Ronco Cindeca |
Jios J.L.,LaSeISiC |
Baronetti G.T.,University of Buenos Aires |
And 2 more authors.
Tetrahedron Letters | Year: 2011
Wells-Dawson heteropolyacids (H 6P 2W 18O 62·24H 2O) were used as catalysts in the Hantzsch-like multicomponent condensation reaction with 3-formylchromones as aldehyde component, a β-ketoester and ammonium acetate, under solvent-free conditions at 80 °C. Although the desired products were obtained, functionalized pyridines were the main reaction product and became the alternative route to dihydropyridine ring formation. Based on the proposed mechanisms for the formation of each of the obtained products, the multicomponent reaction was modified to afford only the functionalized pyridines (60-99%). Our procedure represents a clean alternative for the synthesis of several highly functionalized pyridines. © 2011 Elsevier Ltd. All rights reserved. Source