The efficient synthesis of Hantzsch 1,4-dihydropyridines via metal-free oxidative C[sbnd]C coupling by HBr and DMSO

Abstract

A novel and efficient synthesis of Hantzsch 1,4-dihydropyridines through metal-free oxidative CC coupling process was described. The reaction between benzylic alcohols, 1,3-dicarbonyl compounds and ammonium hydroxide in the presence of HBr in DMSO at 75 °C led to afford 1,4-dihydropyridine in excellent yields. This protocol introduces the use of benzyl alcohols instead of aldehydes as a new modification of the Hantzsch reaction.