Phenylboronic acid catalysed synthesis of 1,5-benzodiazepines via cyclocondensation of o-phenylenediamine and ketones

Abstract

Phenylboronic acid has been found to be an efficient catalyst for the synthesis of 1,5benzodiazepine derivatives via cyclocondensation of o-phenylenediamine and various ketones in good to excellent yields (82-91%) using acetonitrile as solvent at reflux condition. The remarkable advantages offered by this method are easy mild reaction condition, experimental work up and good to excellent yields of products.

One-pot strategy to synthesize seven–membered 1,4-diazepine heterocyclic scaffolds assisted by zinc oxide nanoparticles as heterogeneous catalytic support system

“…[29][30][31] However a large number of methods reported in the literature suffer from several bottlenecks viz the use of drastic conditions, lesser yields, and typical product isolation procedures. Though certain improvements have been proposed to overcome the shortcomings of existing methods by incorporating ionic liquids, 32 silica-supported acids, 33 metal triflates, 34 HY-zeolites, 35 and boronic acids, 36 L-proline, 37 TMSCI/NaI, 38 InCl3, 39 and DBU, 40 in synthetic protocols. Also, the use of microwave, 41 ultrasound -radiation, 42, and aqueous media, 43 have also been reported to achieve the improvement in their synthetic outcomes to some extent.…”

Microwave-Assisted, Solvent Free Preparation of 1,5-Benzodiazepine Derivatives Using Nanomagnetic-Supported Sulfonic Acid as a Recyclable and Heterogeneous Catalyst

“…4 Thus, due to the wide applications of benzodiazepine derivatives in medicine and industry, and in organic reactions, there is an imperative need to develop new methodology for the synthesis of these compounds. Various methods for the preparation of benzodiazepines are reported in the literature nine of which [5][6][7][8][9][10][11][12][13] are listed in Table 2. However, many of these methods have some limitations such as low to poor yields, tedious work-up procedures, hazardous and expensive reagents and solvents, and relatively long reaction times.…”