3-[(5-Chloro-2-methoxy-benzenesulfonyl)-propenyl-amino]-4-[(propenyl)oxy]-benzoic acid methyl ester → 4-(5-chloro-2-methoxy-benzenesulfonyl)-4H-benzo[1,4]oxazine-6-carboxylic acid methyl ester

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A solution of 3-[(5-chloro-2-methoxy-benzenesulfonyl)-propenyl-amino]-4-[(propenyl)oxy]-benzoic acid methyl ester (170 mg, 0.378 mmol) and dichloro(1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)(phenylmethylene)(tricyclohexylphosphine)ruthenium (32 mg, 38 mmol) in toluene (1.7 mL) was stirred at 45° C. for 24 h, then the solvent was evaporated. Chromatography (SiO2, heptane-ethyl acetate gradient) afforded 4-(5-chloro-2-methoxy-benzenesulfonyl)-4H-benzo[1,4]oxazine-6-carboxylic acid methyl ester (75 mg, 50%). Light red solid, MS (ISP)=395.7 (M+H)+.

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