P. Ye, Ning Liu, Yu-wei Chang
Sep 2, 2016
Citations
0
Influential Citations
2
Citations
Quality indicators
Journal
Organic Preparations and Procedures International
Abstract
A review of the literature and patents indicates that several procedures exist for its synthesis. Among these routes, the reduction of 5-methyl-2-[(2-nitrophenyl)amino]thiophene-3-carbonitrile (1) prepared from the reaction of 2-fluoronitrobenzene with 2amino-5-methyl-3-thiophenecarbonitrile 2-amino-5-methyl-3-thiophenecarbonitrile to give 4-amino-2-methyl-10H-thieno [2,3-b][1,5]benzodiazepine (2), has routinely been performed using with stannic chloride. However, the use of large quantities of conc. hydrochloric acid leads to pollution and corrosion problems. These environmental concerns have led to increased interest in alternate processes. For example, Zhou et al. developed an efficient stannic chloride-catalyzed method with sodium hypophosphite (NaHPO2) as a reducing system to obtain 4-amino-2-methyl-10H-thieno[2,3-b][1,5]benzodiazepine (2) leading to a dramatic reduction of the amount of stannic chloride needed. In addition, Wang et al. developed a method using iron powder as the reducing agent, albeit in only moderate yields. As a continuation of our interest in the study of medicinal compounds, we have developed a practical reducing system consisting of tin powder and hydrochloric acid Figure 1