Glycerol Containing Triacetylborate Mediated Syntheses of Novel 2-Heterostyryl Benzimidazole Derivatives: A Green Approach

Table 1

Synthesis of 2-(2-(4-chloro-phenyl)-vinyl)-1-H-benzimidazoles.

Entry	Triacetylborate (mol-%)	glycerol* used (+); not used (−)	Solvents used	Time (h)	Yield (%)
1.	—	−	—	05	50
2.	—	+	Glycerol	05	50
3.	2	−	—	05	60
4.	5	−	—	05	68
5.	10	−	—	05	70
6.	2	+	Glycerol	05	60
7.	5	+	Glycerol	05	78
8. ^#	10 ^#	+ ^#	Glycerol ^#	05 ^#	90 ^#
9.	20	+	Glycerol	05	84
10.	20	−	Ethylene glycol	06	60
11.	20	−	PEG-600	06	0

Reactions were carried out in oil bath using Dean-Stark apparatus at 160°C (entries 2, 6, 7, 8, and 9), 120°C (entry 11), 190°C (entry 10), or under solvent free conditions at 180°C (entries 1, 3, 4, and 5).
∗10 mL glycerol was used in all the above reactions.