Ag₃PW₁₂O₄₀: A Novel and Recyclable Heteropoly Acid for the Synthesis of 1,5-Benzodiazepines under Solvent-Free Conditions

Abstract

o-Phenylenediamines undergo smooth condensation with ketones having hydrogens at a-position on the surface of heteropoly acid (Ag 3 PW 12 O 40 ) under extremely mild conditions to afford the corresponding 1,5-benzodiazepines in excellent yields with high selectivity. The catalyst can be recovered by simple filteration and can be reused in subsequent reactions.

Solvent-Free one pot synthesis of benzo-[b]-1,4-diazepines using reusable sulfamic acid catalyst

“…Conversely, the commonly employed methods involve the cyclocondensation of 1,2-diamines with ketones [6], enones [7], ȕ-haloketones [8], using Ytterbium triflate [9], BF 3 -etherate [10], polyphosphoric acid [11], MgO and POCl 3 [6] , ionic liquids [12], under microwave irradiation *Crresponding author. E-mail: rppawar@yahoo.com [13], SbCl 3 -Al 2 O 3 [14] and zinc montmorillonite heterogeneous catalyst [15], sulfated zirconia [16], Ag 3 PW 12 O 40 [17], CH 3 COOH [18], MCM-41 zeolite [19], Piperidine-AcOH [20], etc. These known methods of benzodiazepine synthesis suffered from limitations such as harsh reaction conditions, expensive reagents, low yields, relatively long reaction time and formation of side products.…”

Hydrated ferric perchlorate, Fe(ClO4)3.XH2O in organic synthesis. A short review

“…A variety of catalysts such as BF 3 .OEt 2 [101], NaBH 4 [102], PPA-SiO 2 [103], MgO-POCl 3 [104], Yb(OTf) 3 [105], Al 2 O 3 -P 2 O 5 [106], HOAc-microwave [101][102][103][104][105][106][107], SO 4 2--ZrO 2 [108], I 2 [109], InBr 3 [110], Ag 3 PW 12 O 40 [111], [L-proline] 2 Zn [112], Solid acid [113] and ionic liquids [114,115] have been employed to affect this transformation. Due to interesting application of 1,5-benzodiazepines, we have recently reported a novel and efficient solvent-free process demonstrated for the synthesis of 1,5-benzodiazepines using ferric perchlorate as a catalyst (Scheme 17).…”

Green and efficient method for the synthesis of 1,5-benzodiazipines using phosphate fertilizers as catalysts under free solvent

“…In order to develop environmentally friendly organic reactions, the synthesis of benzodiazepines using different solid acid catalysts [27][28][29] and heteropolyacid catalysts using THF or acetonitrile as reaction solvent [30][31] has also been investigated. Recently, a crystalline iron-based metal-organic framework MOF-235 was synthesized, characterized by different techniques and used as a heterogeneous catalyst for the synthesis of 1,5-benzodiazepines by the cyclo-condensation of 1,2-diamines with ketones 32 .…”