1,5-Benzodiazepine derivatives were synthesized by the condensation reactions of o-phenylenediamine and ketones catalyzed by bismuth (III) salts under mild conditions. This method is easy, efficient, environment and eco-friendly, free of toxic catalysts, and gives good to excellent yields of 1, 5-benzodiazepines. 1. Introduction The synthesis of 1,5-benzodiazepines and their derivatives have attracted considerable attention of researchers, including pharmaceutical and organic synthetic chemists, in recent years because of their medicinal properties namely antianxiety, hypnotic, antidepressive, tranquilizing, antiinflammatory, anticonvulsant, antifeedant, antibacterial, and analgesic agents [1–4]. In addition, 1,5-benzodiazepines are valuable synthons used for the preparation of other fused ring compounds such as triazolo, oxazino or furano-benzodiazepines [5, 6]. Benzodiazepines derivatives are also used in industry as dyes for acrylic fibers in photography [7]. Due to their wide range of pharmacological activities and industrial and synthetic applications, the development of practical and green protocols continues to be a challenging endeavour in synthetic chemistry. In recent years, many methods for their preparation are reported in the literature. These include condensation reactions of o-phenylenediamine with α, β-unsaturated carbonyl compounds [8], β-haloketones [9], β-aminoketones [10] or ketones promoted by BF3·OEt2 [11], NaBH4 [12], polyphosphoric acid or SiO2 [13], ceric ammonium nitrate (CAN) [14], MgO/POCl3 [15], Yb(OTf)3 [16], Al2O3/P2O5 or AcOH under microwave conditions [17], Amberlyst-15 in ionic liquid [18], CeCl3/7H2O/NaI supported on silica gel [19], InBr3 [20], 1-butyl-3-methylimidazolium bromide ([bmim]Br) [21], Sc(OTf)3 [22], and Nb(Cl)3 [23]. However, many of these methodologies have one or more shortcomings, such as long reaction time, poor yields of the products, drastic reaction conditions, occurrence of several side products, expensive reagents, high catalyst loading, and tedious workup procedures. Bismuth (III) salts have emerged in the recent years as “eco-friendly” reagents suitable for green chemistry. They have received considerable attention as mild Lewis acids [24–27] for an array of organic transformations because the catalysts are inexpensive, relatively nontoxic, moisture and air tolerant, environmentally benign, and commercially available. Ionic liquid is used as an alternative to traditional solvents for organic reactions particularly in the area of green chemistry. Thus, considering the advantages and applications
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