Revisit to the Reaction of O-Phenylene Diamine with Thiosemicarbazide to Give Benzimidazole-2-Thione Rather than Benzotriazine-2-Thione and its Glycosylation

Abstract

Reaction of o-phenylene diamine with thiosemicarbazide did not give benzotriazine-2-thione 2 as reported, although the product was found to be benzimidazole-2-thione 3. Glycosylation of 3 with acetobromo sugars 4a-4b gave the respective thioglycosides 7a-7d in addition to minor products of the nucleosides 8a and 8b, in the case of the gluco- and galacto-analogs, respectively. The regioselectivity of glycosylation reaction has been investigated.

Keywords:

• Imidazole-thione
• benzotriazine-thione
• thioglycosides
• glycosyl-imidazole
• thiosemicarbazide

Acknowledgments

The authors thank the Higher Education Commission (H. E. C.) Pakistan for their valuable support (Project No. 20-697/R&D/06/38). Thanks also are due to Prof. Dr. Atta-Ur-Rahman and Prof. Dr. M. I. Choudhary for their valuable help.