One-Pot Three Component Synthesis of 2,3-Dihydro-1H-1,5- benzodiazepines by a Magnetically Recyclable Nanocatalyst Fe3O4@SiO2- Cu-salen

Abstract

Benzodiazepines and their polycyclic derivatives are an important class of bioactive compounds. Many functionalized benzodiazepines are widely used as anti-convulsant, antianxiety, analgesic, sedative, anti-depressive and hypnotic agents. These compounds also, finding applications as dyes for acrylic fibers and anti-inflammatory agents. 1,5- Benzodiazepines are key intermediates for the synthesis of various fused ring compounds such as triazolo-, oxadiazolo- and oxizino-diazepines [1]. Due to their broad spectrum of biological activity, these compounds received a lot of attention towards their synthesis. The general method for the synthesis of 1,5-benzodiazepines involves an acid-catalyzed condensation of o-phenylenediamines with α,β-unsaturated carbonyl compounds or β-halo ketones or ketones. Many reagents have been utilized for this reaction including polyphosphoric acid-SiO2, BF3·OEt2, NaBH4, Yb(OTf)3, MgO-POCl3, and more recently acetic acid under microwave conditions [2]. In continuation of our research towards the synthesis of biologically important molecules in this study various 1,5-benzodiazepine derivatives were synthesized by the condensation reaction of o-phenylenediamine with various ketones using the Fe3O4@SiO2-Cusalen [3] as an efficient, heterogeneous magnetically recyclable catalyst (Fig. 1).