tert-butyl 8-(hydroxymethyl)-3,4-dihydro-2H-1,4-benzoxazine-4-carboxylate → Tert-butyl 8-formyl-2,3-dihydro-4H-benzo[B][1,4]oxazine-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of 8-hydroxymethyl-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester (591.2 mg, 2.2 mmol) in dioxane (4 mL) was added preactivated MnO2 (2.00 g, 22.3 mmol), and the resulted mixture was heated at 80° C. for overnight. The resulted mixture was then 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-formyl-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid tert-butyl ester (491.5 mg) as a white solid. MS m/z: 286.0 (M+Na)+.

Provenance & Evidence