Mn(OAc)3 [20], and many ionic salts were established as
effective catalysts [21]. However, most of these protocols
involve expensive reagents, strongly acidic conditions, long
reaction time, high temperatures, and stoichiometric amounts
of catalysts, and give unsatisfactory yields. Therefore, the
discovery of a new and inexpensive catalyst for the preparation
of 3,4-dihydropyrimidin-2(1H)-ones under mild conditions is
important.