6-(Hydroxymethyl)-2H-benzo[b][1,4]thiazin-3(4H)-one → 3-Oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

To a solution of 6-hydroxymethyl-4H-benzo[1,4]thiazin-3-one (360 mg, 1.8 mmol) in THF/CHCl3 (2:1, 18 mL) was added MnO2 (1.6 g, 18 mmol) and the resulting suspension was heated to 70° C. and stirred for 4 h. The suspension was filtered through diatomaceous earth and the filtrate was concentrated. The resulting solid was triturated with EtOAc/hexanes (1:1) and a minimal amount of CH3OH to provide 200 mg (56%) of the title compound as a tan solid. MS (ESI): exact mass calculated for C9H7NO2S, 193.02; m/z found, 194.1 [M+H]+. 1H NMR (500 MHz, CDCl3): 9.94 (s, 1H), 8.78 (br s, 1H), 7.54-7.49 (m, 2H), 7.37 (d, J=1.5, 1H), 3.52 (s, 2H).

Provenance & Evidence