Dichloro dicyano quinone (DDQ) as coupling reagent for high yield synthesis of 3,4-dihydropyrimidin-2(1H)-ones

DDQ catalyzes efficiently the three‐component condensation reaction of aldehyde, β‐ketoester and urea in refluxing acetonitrile to afford the corresponding dihydropyrimidinones. Compared to the classical Biginelli reaction conditions, this new approach consistently has the advantage of excellent yields (80‐92%) and short reaction times 1.5‐2.5 h.