Diethyl (ethoxymethylene)malonate → HCID 13188588, compound

Participants

Reaction Steps

A mixture of 1.11 g (5.5 mmols) of 7-chloro-8-fluoro-3-methyl-2,3-dihydro-4H-1,4-benzoxazine and 1.4 g (6.2 mmols) of diethyl ethoxymethylenemalonate was stirred for 2 hours while heating at 130°-140° C. (bath temperature). After confirming disappearance of the starting benzoxazine compound by thin-layer chromatography, 5 g of ethyl polyphosphate was added to the reaction mixture and the mixture was again allowed to react for 1 hour at 140° C. (bath temperature). After cooling, 20 ml of water was added to the mixture and the precipitate formed was extracted with 150 ml of chloroform. The chloroform extract was dried with sodium sulfate and chloroform was then distilled off. The resulting residue was purified by silica gel (20 g) column chromatography using methanol-chloroform (5:95 by volume) as an eluant to provide 1.2 g (67.0% yield) of ethyl 9-chloro-10-fluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylate with m.p. 263°-264° C.

Provenance & Evidence