Chloroacetyl chloride → 4-Chloroacetyl-1,3-dimethyl-1,4,9,10-tetrahydropyrazolo[4,3-b][1,5]benzodiazepin-10-one

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Reaction Steps

2 g of chloroacetyl chloride and 2 g of triethylamine are added dropwise at the same time over the course of 40 minutes to a boiling solution of 2.3 g of 1,3-dimethyl-1,4,9,10-tetrahydropyrazolo[4,3-b][1,5]benzodiazepin-10-one in 30 ml of absolute dioxane, and the mixture is stirred for a further 3 hours. It is then allowed to cool and is filtered; the filtrate is concentrated to dryness and chromatographed over a silica gel column by means of a 1:1 mixture of petroleum ether and ethyl acetate, and the product is recrystallized from toluene to yield 2.0 g of 4-chloroacetyl-1,3-dimethyl-1,4,9,10-tetrahydropyrazolo[4,3-b][1,5]benzodiazepin-10-one, mp 246° to 248° C. (dec.).

Provenance & Evidence