Ammonium Chloride → Methyl 6-chloro-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-8-carboxylate

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Reaction Steps

A solution of 100 ml of aqueous 0.78N ammonium chloride and 50 ml of dimethylformamide is heated at 85° C. and 40 g of powdery iron is added thereto under stirring followed by addition of a solution of 63.5 g of ethyl 4-chloro-2-methoxycarbonyl-6-nitrophenoxyacetate in 150 ml of dimethylformamide over 15 minutes. The reaction temperature rises to 95° C. The resulting solution is stirred at 80°-90° C. for an hour and 400 ml of dimethylformamide is added thereto. The whole solution is filtered with suction through hot celite. The mother liquor is poured into 2 1 of ice-cold water and the precipitated crystals are collected by filtration to give 43.6 g of methyl 6-chloro-3,4-dihydro-3-oxo-2H-1,4-benzoxazine-8-carboxylate, melting at 239°-241° C.

Provenance & Evidence