SiO2/H2SO4: An Efficient Catalytic System for Solvent-free 1, 5-benzodiazepines Synthesis

Mohammad Reza Shushizadeh,Narges Dalband

doi:10.17795/jjnpp-3624

Abstract

1, 5-Benzodiazepines have been investigated extensively by organic chemists due to their medicinal and pharmacological properties. These compounds are synthesized by condensation of o-phenylenediamines with carbonyl compounds in the presence of acid catalysts. During our studies on the application of silica resin with acid functional moieties, we found that SiO2/H2SO4 mixture is a simple and efficient catalyst for this method under microwave irradiation. The reaction was carried out simply by grinding SiO2/H2SO4 mixture with o-phenylenediamine, and ketone in the mortar; then the mixture was poured out into a sealed flask. Subsequently, it was irradiated in a microwave oven. In this method a series of cyclic and acyclic ketones underwent above conversion to form corresponding 1, 5-benzodiazepines. In conclusion, this method is a simple, rapid, and high yielding reaction (78-95%).

Highlights

Often when carrying out a reaction in a microwave oven, the use of a solvent can be avoided, which is important in order to make the synthesis more environmentally friendly as it is observed in green chemistry
During our studies on the application of silica resin with acid functional moieties [18], we found that SiO2/ H2SO4 mixture is a simple and efficient catalyst for solvent-free synthesis of 1,5-benzodiazepines under microwave irradiation, as it was followed in (Figure 1)
1, 5-benzodiazepines Synthesis derwent above conversion to form a series of 1,5-benzodiazepines

Summary

Background

1,5-Benzodiazepines and their derivatives have been investigated extensively by organic chemists due to their medicinal properties such as analgesic and anti-inflammatory activities [1]. Considerable attention has been devoted to heterogeneous organic transformations utilizing inorganic solid acids [15] Some of these compounds such as silica sulfuric acid (SSA) have been employed widely as efficient catalysts for several organic reactions [16]. Often when carrying out a reaction in a microwave oven, the use of a solvent can be avoided, which is important in order to make the synthesis more environmentally friendly as it is observed in green chemistry. These observations led us to investigate possibility of improving methods used for solvent-free synthesis of 1,5-benzodiazepine scaffold

Objectives

Reagents and Materials

General Procedure

Results

Discussions