Dimethylformamide potassium carbonate → Ethyl 8-chloro-1-cyclopropyl-7-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylate

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Reaction Steps

Reaction of 3-chloro-2,4-difluoro-benzoyl chloride with diethyl malonate gives diethyl (3-chloro-2,4-difluoro-benzoyl)-malonate, and partial hydrolysis and decarboxylation lead to ethyl (3-chloro-2,4-difluoro-benzoyl)-acetate, which is reacted with ethyl orthoformate/acetic anhydride to give ethyl 2-(3-chloro-2,4-difluorobenzoyl)-3-ethoxy-acrylate; further reaction with cyclopropylamine leads to ethyl 2-(3-chloro-2,4-difluoro-benzoyl)-3-cyclopropylaminoacrylate, which is cyclized with potassium carbonate/dimethylformamide to give ethyl 8-chloro-1-cyclopropyl-7-fluoro-1,4-dihydro-4-oxo-3 -quinolinecarboxylate; hydrolysis then finally leads to the corresponding carboxylic acid. The reaction sequence described can be represented by the following equation: ##STR4##

Provenance & Evidence