Sodium hydride → Ethyl 2-[3-(4-methoxyphenyl)prop-2-en-1-ylidene]-3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carboxylate

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Reaction Steps

Under ice-cooling, sodium hydride (4.65 g, content 60%) was added in small portions to a THF solution (300 ml) containing (2E)-3-(4-methoxyphenyl)acrylaldehyde (10 g) synthesized by the process described in Reference Example 1 and ethyl 2-(diethoxyphosphoryl)-3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carboxylate (21.7 g, synthesized according to the process disclosed in WO00/63197). The resulting mixture was slowly warmed up to room temperature and stirred overnight. The same aldehyde as above (1.5 g) was added thereto and stirred for another 2 hours. The resulting mixture was concentrated under reduced pressure, and ethyl acetate (30 ml), hexane (100 ml), a 1N aqueous hydrochloric acid solution (50 ml) and water (600 ml) were added to the residue, followed by stirring at room temperature for 6 hours. The solid was collected by filtration and dried under reduced pressure. Ethyl 2-[3-(4-methoxyphenyl)prop-2-en-1-ylidene]-3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carboxylate (22.43 g) was obtained as a yellow solid.

Provenance & Evidence