Ethyl pentafluorobenzoylacetate

A mixture of the known compound, ethyl pentafluorobenzoylacetate [J. Org. Chem., 35, 930 (1970)] (25 g), ethyl orthoformate (20 g), and acetic anhydride (23 g) was refluxed for 2 h. The reaction mixture was evaporated to dryness under reduced pressure. The residue was dissolved in diethyl ether and allowed to react with cyclopropylamine (5.1 g) to give ethyl 2-pentafluorobenzoyl-3-cyclopropylaminoacrylate (28 g), melting point 89°C. 

Ethyl pentafluorobenzoylacetic ester undergoes cyclization into l-oxo-3-pentafluorophenyl-l/7-pyrano[4,3-6]6,7,8,9-tetrafluorochromone (92IZV2186) (Scheme 69). 

The oxime (95) (obtained from ethyl pentafluorobenzoylacetate and nitrous acid) cyclizes on heating to give 3-ethoxycarbonyl-5,6,7,8-tetrafluorobenzo-xazin-4-one (96) nucleophilic displacemrait of fluoride from the latter occurs on treatment with hydroxylamine, phenylhydrazine, or bemgriamine, but hydrolysis leads to the ring-opening reactions shown (Scheme 25)." > ... 

Ethyl pentafluorobenzoylacetate (33), benzoyl(pentafluorobenzoyl)methane (34), and bis(pentafluorobenzoyl)methane (35) have been synthesized as shown in Scheme 11. The first of these is not a new compound, having been prepared in the early 1960 s by treatment of pentafluorobenzoyl chloride with diethyl malonate in the presence of magnesium ethoxide followed by hydrolysis of the diester CeF8 C0 CH(C02Et)a thus produced, and by condensation of ethyl pentafluorobenzoate with ethyl acetate in the presence... 

The reaction with ethyl orthoformate affords ethyl 2-ethoxymethylidene-pentafluorobenzoylacetate, which on heating undergoes cyclization into 3-ethoxycarbonyl-5,6,7,8-tetrafluorochromone (93JFC(65)37, 93IZV362). 

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