Synthesis of benzimidazole and benzoxazole derivatives catalyzed by PNSS and PINZS as nano catalysts.

Entry	Amine	Orthoester/formic acid	Product	Time (min)			M. P. (°C)
				Yielda (%)			Observed	Reported
				ZnO		SiO2
1		CH(OEt)3		10		25	164–166	168–170 (ref. 54)
				98		96
2		CH(OMe)3		15		17	164–166	168–170 (ref. 54)
				94		93
3		HCOOH		10		13	164–166	168–170 (ref. 54)
				92		92
4		CH(OEt)3		13	20		198–200	203–205 (ref. 54)
				96	70
5		CH(OEt)3		12	30		107–109	109–111 (ref. 54)
				93	97
6		CH(OMe)3		45	60		107–109	109–111 (ref. 54)
				95	94
7		CH3CH(OEt)3		30	50		194–196	194–196 (ref. 54)
				92	90
8		HCOOH		35	40		107–109	109–111 (ref. 54)
				98	97
9		CH(OEt)3		7	15		Oil	Oil54
				96	94
10		CH(OMe)3		5	5		Oil	Oil54
				96	92
11		CH3CH(OEt)3		3	5		Oil	Oil54
				98	96
12		HCOOH		12	20		Oil	Oil54
				94	93

^aIsolated yield.