Dimethylformamide → 2,4,5-Trimethoxybenzoyl chloride

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반응 단계

2,4,5-Trimethoxybenzoic acid (500 g) was suspended in dried toluene (2 l) and to the suspension, thionyl chloride (206 ml) and N,N-dimethylformamide (1.0 ml) were added at room temperature, and the mixture was stirred at 80° C. for 1 hour. The reaction mixture was concentrated under reduced pressure. To the resultant residue, n-hexane was added and through co-boiling the mixture, 2,4,5-trimethoxybenzoyl chloride was obtained. To the resultant compound, 2-amino-4-methoxycarbonyl-1,3-thiazole (372.7 g) and 1,2-dichloroethane (4.5 l) were added and the mixture was refluxed for 6 hours. After completion of reaction, the reaction mixture was allowed to cool. Crystals so precipitated were collected by filtration, washed with 1,2-dichloroethane, and air-dried. The crystals were suspended in water (8 l) and to the suspension, ice (2 kg) was added. While cooling, a solution of sodium hydroxide (94 g) in water (850 ml) was added thereto to thereby adjust the pH of the suspension at about 7.5. Subsequently, the mixture was stirred for 3 hours at room temperature. Crystals so precipitated were collected by filtration, washed with water, and air-dried to thereby obtain the title compound (702.7 g).

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