2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → HCID 14156759, compound

Participants

Reaction Steps

A solution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 22 g) in toluene (200 ml) was added dropwise to a refluxing solution of 4-bromo-1,2-dihydrobenzo[b]pyrrolo[3,2,1-jk][1,4]benzodiazepine (10 g) in toluene (750 ml) under nitrogen. The mixture was refluxed for 1 hour, cooled, stirred with triethylamine (3 g) for 10 minutes, and fed to a flash chromatography column (slurry packed with silica, 300 g in dichloromethane). The adsorbed material was eluted with dichloromethane (4 L); 1% methanol/dichloromethane (2 L); and 1% methanol/0.5% ammonium hydroxide/dichloromethane (2 L), whereby the desired product was separated from the remaining quinone. The crude product (10 g) was purified further on a second flash chromatography column (silica gel, 180 g; eluted with 20:80 hexane/dichloromethane, 6 L). The desired product was isolated as a solid (5.4 g). Recrystallization from ethanol (70 ml) at 0° C. gave 3.2 g of crystals which turned to powder after vacuum drying at 110° C., m.p. 122°-123° C.

Provenance & Evidence