[Cl:1][C:2]1[CH:17]=[CH:16][C:5]2[CH2:6][N:7]3[CH:14]=[C:13]([CH3:15])[CH:12]=[C:8]3[C:9](=O)[NH:10][C:4]=2[CH:3]=1.P(Cl)(Cl)([Cl:20])=O.C(Cl)Cl.C(=O)([O-])[O-].[Na+].[Na+]>ClC1C=CC=CC=1>[Cl:1][C:2]1[CH:17]=[CH:16][C:5]2[CH2:6][N:7]3[CH:14]=[C:13]([CH3:15])[CH:12]=[C:8]3[C:9]([Cl:20])=[N:10][C:4]=2[CH:3]=1To a suspension of 1.1 g of 8-chloro-2-methyl-10,11-dihydro-5H-pyrrolo[2,1-c][1,4]benzodiazepine-11-one in 20 mL of chlorobenzene is added 680 mg of phosphorous oxychloride. The mixture is heated at 100°-110° for 1 hour, then allowed to cool to room temperature. Methylene chloride (150 mL) is added to the stirred reaction mixture which is then poured into a mixture of ice and aqueous sodium carbonate. After being shaken vigorously, the methylene chloride layer is separated, the aqueous layer is further extracted with 200 ml of diethyl ether; the combined extracts are dried (anhydrous magnesium sulfate), decolorized with charcoal, and evaporated to dryness to yield 8,11-dichloro-2-methyl-5H-pyrrolo[2,1-c][1,4]benzodiazepine as a viscous oil which is used in the next step without further purification.
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