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

HRID 419162Notes

Reaction equation

[C:1]([O:5][C:6]([N:8]1[C:13]2[CH:14]=[CH:15][CH:16]=[C:17]([CH2:18][OH:19])[C:12]=2[O:11][CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]>O1CCOCC1.O=[Mn]=O>[C:1]([O:5][C:6]([N:8]1[C:13]2[CH:14]=[CH:15][CH:16]=[C:17]([CH:18]=[O:19])[C:12]=2[O:11][CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]

Participants

Conditions

Temperature: 80 °C

Procedure

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)+.

Workup

temperatureThe resulted mixture was then cooled to r.t.
filtrationfiltered
washThe solid was washed with EtOAc (20 mL×3)
concentrationconcentrated under reduced pressure
customThe residue was purified by flash column chromatography on silica gel

Sources & evidence

ORD record: ord-2cac6dc348f743518269db58caccd4a1
Source dataset: uspto-grants-2012_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08093247B2

Reaction notes

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