Diethyl Carbonate → Ethyl 2,4-dichloro-5-fluorobenzoylacetate

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Reaction Steps

Condensation of 2,4-dichloro-5-fluoroacetophenone 2 with diethyl carbonate in the presence of NaH yielded ethyl 2,4-dichloro-5-fluorobenzoylacetate 3. Treatment of the latter with triethyl orthoformate in acetic anhydride gave the carbon homologue enol ether intermediate 4 which was allowed to react with a slight excess of cyclopropylamine in methylene chloride at room temperature to give the enaminoketoester 5. Cyclization of the latter with 1 molar equivalent of NaH in refluxing dioxane yielded ethyl 1,4-dihydro-4-oxo-quinoline-3-carboxylate 6 which was then hydrolysed with aqueous NaOH to give 1-cyclopropyl-6-chloro-7-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid (IM) 7. See also Scheme 1 below (Maurer, F. and Grohe, K., DE 3 435 392 through Chem. Abst., Vol. 105, No.5, 1984, pp. 97158e). Compound data:

Provenance & Evidence