Acetic Acid → 6-phenyl-8-chloro-4H-s-triazolo[4,3-a] [1,4]benzodiazepine-1-carboxylic acid methyl ester

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Reaction Steps

A mixture of 1.62 g (0.005 mole) of 6-phenyl-8-chloro-4H-s-triazolo[4,3-a][1,4]benzodiazepine-1-carboxaldehyde [cp. Example 1 a)], 20 ml of methanol, 1.225 g (0.025 mole) of sodium cyanide, 8.70 g (0.10 mole) of manganese dioxide and 0.40 g of glacial acetic acid is stirred for 16 hours at 25°. The reaction mixture is diluted with methanol, filtered through a layer of kieselguhr and the filtrate concentrated by evaporation. The residue is dissolved in methylene chloride, this solution washed with water and saturated sodium chloride solution, dried over magnesium sulphate and concentrated by evaporation. The oily residue is chromatographed on silica gel (Merck, 0.063 - 0.2 mm particle size) with ethyl acetate/methanol (9:1) as eluant. The fractions containing the desired product [Rf = 0.7 in the eluant system ethyl acetate/isopropanol (7:1)] are combined, concentrated by evaporation, and the residue crystallised from ethyl acetate to obtain 6-phenyl-8-chloro-4H-s-triazolo[4,3-a] [1,4]benzodiazepine-1-carboxylic acid methyl ester, M.P. 216°-217°.

Provenance & Evidence