8-({5-Chloro-3-[(4-chloro-3-trifluoromethyl-benzenesulfonyl)-methoxymethyl-amino]-pyridin-2-yl}-hydroxy-methyl)-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester → 8-{5-Chloro-3-[(4-chloro-3-trifluoromethyl-benzenesulfonyl)-methoxymethyl-amino]-pyridine-2-carbonyl}-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester

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Reaction Conditions

Reaction Steps

To a solution of 8-({5-chloro-3-[(4-chloro-3-trifluoromethyl-benzenesulfonyl)-methoxymethyl-amino]-pyridin-2-yl}-hydroxy-methyl)-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester (562.7 mg, 0.91 mmol) in dioxane (4 mL) was added preactivated MnO2 (932.9 mg, 9.12 mmol), and the resulted mixture was heated at 80° C. for two hour. The resulted mixture was cooled to r.t., and filtered. The solid was washed with EtOAc (20 mL×3). EtOAc washing solution was combined with dioxane filtrate, and concentrated under reduced pressure. The residue was purified by flash column chromatography on silica gel to provide 8-{5-chloro-3-[(4-chloro-3-trifluoromethyl-benzenesulfonyl)-methoxymethyl-amino]-pyridine-2-carbonyl}-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester (510.2 mg) as yellow syrup. MS m/z: 676.0 (M+H)+.

Provenance & Evidence