A green synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by Sn(HPO₄)₂.H₂O nanodisks under solvent-free condition at room temperature

Figures & data

short-legendScheme 1. Synthesis of 3,4-dihydropyrimidin-2-ones.

Table 1. Synthesis of dihydropyrimidin-2(1H)-ones catalyzed by Sn(HPO4)2.H2O nanodisks with different catalyst loadings under solvent-free condition.

Entry	Reaction media	Catalyst load (mol%)	Time (h)	Yield (%)^a
1	Neat	3	2	80
2	Neat	5	2.5	85
3	Neat	10	1	97
4	Neat	15	1	97
5	Neat	20	1	96
^aIsolated yield.

Table 2. Synthesis of dihydropyrimidin-2(1H)-ones and thiones catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature.

Entry	R^1	R^2	R^3	X	Time(h)	Yield^a(%)
1	C6H5	C2H5O	CH3	O	0.75	96
2	4–(CH3O)–C6H4	C2H5O	CH3	O	1.2	92
3	4–(NO2)–C6H4	C2H5O	CH3	O	0.5	95
4	4–(Cl)–C6H4	C2H5O	CH3	O	0.6	94
5	2,4–(Cl)2–C6H3	C2H5O	CH3	O	0.7	93
6	3–(OH)–C6H4	C2H5O	CH3	O	1.5	90
7	C6H5CH = CH	C2H5O	CH3	O	1.8	88
8	(CH3)2CH	C2H5O	CH3	O	2.1	86
9		C2H5O	CH3	O	1.8	84
10	C6H5	CH3O	CH3	O	0.8	96
11	4–(CH3O)–C6H4	CH3O	CH3	O	1.3	92
12	4–(NO2)–C6H4	CH3O	CH3	O	0.6	95
13	C6H5	C2H5O	CH3	S	1.0	95
14	4–(CH3O)–C6H4	C2H5O	CH3	S	1.4	90
15	4–(Cl)–C6H4	C2H5O	CH3	S	0.8	93
^aIsolated yield, stirring at 25–30°C.
^bThe structures of all the compounds were determined by using ^1H NMR, FT-IR, MS (m/z), and elemental analyses and they are in good agreement with the authentic samples 17–20.

Table 3. Recycling of Sn(HPO4)2.H2O nanodisks catalyst.

Entry	No. of run	Time (h)	Conversion^b (%)	Yield^a (%)
1	First run	0.75	97	96
2	Second run	0.75	96	95
3	Third run	0.75	94	95
4	Fourth run	0.75	93	94
5	Fifth run	0.75	90	92
^aIsolated yield.
^bDetermined by GC.

short-legendScheme 2. Synthesis of 1, 5-benzodiazepines.

Table 4. Synthesis of 1,5-benzodiazepines catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature.

^aIsolated yield; stirring at 25–30°C.

^bThe structures of all the compounds were determined by using ^1H NMR, FT-IR, MS (m/z), and elemental analyses and they are in good agreement with the authentic samples 43–47.