Highly Efficient and Facile Method for Synthesis of 2-Substituted Benzimidazoles via Reductive Cyclization of O-Nitroaniline and Aryl Aldehydes

Table 1

Reaction of various aryl aldehydes with o-nitroaniline.

Entry	Substrate	Product^a	Time (hour)	Yield (%)^b
	Ar
1		2a	2	95
2		2b	1.8	95
3		2c	2	94
4		2d	1.8	92
5		2e	2.2	91
6		2f	1.5	94
7		2g	1.8	90
8		2h	1.7	93
9		2i	1.8	91
10		2j	1.6	92
11		2k	1.2	94
12		2l	1.9	91
13		2m	1.7	92

^aAll compounds are known, and their physical and spectroscopic data were in good agreement with those of authentic samples.
^bYields refer to pure isolated products.