A Green, Expeditious, One-Pot Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones Using a Mixture of Phosphorus Pentoxide-Methanesulfonic Acid at Ambient Temperature

Table 1

Comparison of reaction conditions and yield of product (4a) with reported methods versus the present method.

Entry	Reagent	Condition	Time	Yield (%)	Reference
1	Methanesulfonic acid	Ethanol, reflux	1 h	95	[11]
2	P2O5	Ethanol, reflux	4 h	91	[12]
3	Chlorosulfonic acid	Solvent free, 60^°C	30 min	93	[35]
4	P2O5/SiO2	Solvent free, 85^°C	2 h	95	[36]
5	ZnCl2	Solvent free, 80^°C	20 min	90	[40]
6	I2	Solvent free, 90^°C	15 min	86	[41]
7	CF3COONH4	Solvent free, 80^°C	10 min	98	[38]
8	1:10 P 2O 5/MeSO 3H	S olvent free, rt	5  min	94	—