1. 7 chloro-1-methyl-5-phenyl-1,4-benzodiazepine-2,3 dione: prepared as per patent No: US 3984398

 2. Nickel/Aluminium alloy: SD Fine Chem

 3. Sodium carbonate: Commercial

 4. Isopropyl alcohol (IPA): SD Fine Chem

 5. DM Water: Commercial

 

6. Methylene Di chloride(MDC): SD Fine Chem

 

In a 2L flask fitted with mechanical stirrer, nitrogen inlet & thermometer pocket , isopropy lalcohol (800ml) was charged followed by Clobazam (7 chloro-1-methyl-5-phenyl-1,4-benzodiazepine-2,3 dione,100gm) at room temperature followed by Demineralized water (DM water, 800ml), sodium carbonate (5gm). Nickel /aluminium alloy(50gm) was added over 2h time at room temperature. The reaction mass was heated 80-85°C and refluxed for 10 h.The reaction was monitored by TLC (7:3,cyclohexane:ethyl acetate) till complete conversion. Further reaction mass cooled to 25-30°C and filtered, followed by top wash to wet cake with MDC (Methylene Dichloride) (200ml). Further MLR was concentrated to get crude mass 85 g. This crude product (10 g) was column purified over silica gel (5% ethylacetate:N-hexane =7:3) afforded the desired product as off white solid 8.3 g, Yield: 88%

1. During heating of  Ni-Al alloy , froathing may be observed.
2. Spent Ni after the reaction is pyrophoric. Should be immediately kept under water

1H NMR:(CDCl3δ ppm):1.92(3H,Doublet), 3.22(3H,Quartet),6.55(1H,Singlet), 6.82-7.39(8H, Ar-H)

13C NMR:(CDCl3δ ppm):134.8(C-Cl),140.6,141.8(C-NH),171.8(C=O)

 

Larry K Keefer and Geeerge Lunn, Chemical Reviews, 1989, 89,3, 459-502

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