Sulfuric Acid → 9H-Dibenz(b,f)imidazo(1,2-d)(1,4)diazepine

Participants

Reaction Steps

9H-Dibenzo[b,f]imidazo[1,2-d][1,4]diazepine [(5H-dibenzo[b,e][1,4]diazepine-11-yl)amino]acetaldehyde dimethyl acetal (30.0 g., 101.0 mmol.) is dissolved in 100 ml. of concentrated sulfuric acid and stirred at room temperature for 3 hours. The product is isolated by pouring the acid solution cautiously, and in portions into ice-cold distilled water, and carefully adding the resulting slurry to 3.0 L. of cold 10% aqueous sodium hydroxide solution. The product is extracted with chloroform; the chloroform layer is back-extracted with 10% aqueous sodium hydroxide followed by washing with a brine soltuion and then the chloroform solution is dried over magnesium sulfate. After filtration and concentration in vacuo, a residue is obtained, which is dissolved in 800 ml. of hot ethyl acetate, filtered to remove insoluble material, and then concentrated to a volume of 500 ml. On colling, 16.34 g. (70.0%) of 9H-dibenzo[b,f]imidazo[1,2-d][1, 4]diazepine of melting point 215°-217° C. is obtained in the form of prisms. An additional 5.23 g. (22.4%) of product is obtained in two additional crops.

Provenance & Evidence