80 ml of isopropanol is added to 120 ml of a 20% solution of dimethylamine in dioxane. After this has cooled to 0°, additions are made, with stirring, of 3.7 g (0.075 mole) of sodium cyanide and, after 5 minutes, of a solution of 4.8 g (0.015 mole) of 6-phenyl-8-chloro-4H-s-triazolo[4,3-a][1,4]benzodiazepine-1-carboxaldehyde [see Example 1 a)] in 50 ml of dioxane/isopropanol (1:1), as well as of 13 g of manganese dioxide. After 10 minutes, a further addition is made of 13 g of manganese dioxide (total 0.3 mole), and the mixture subsequently stirred for 4 hours at 0°. After the addition of methylene chloride, the reaction mixture is filtered and the filtrate concentrated by evaporation. Crystallisation of the residue from ethyl acetate/petroleum ether yields N,N-dimethyl-6-phenyl-8-chloro-4H-s-triazolo[4,3-a][1,4]benzodiazepine-1-carboxamide, M.P. 180°-181° C.
