In 1893, Petro Biginelli reported the first synthesis of 3,4-dihydropyrimidin-
2(1H)-one (DHPM) of type 4 by a very simple onepot
condensation reaction of an aromatic aldehyde 1, b-ketoesters
2 and urea 3 under strongly acidic conditions.1 However, this
protocol often provides only low to moderate yields of the desired
target molecules.