Methanol → 6-nitro-3,4-dihydro-2H-1,4-benzoxazine

Participants

Reaction Steps

To a suspension of 6-nitro-4-H-benzo[1,4]oxazin-3-one (7.84 g, 40.38 mmol) in tetrahydrofuran (100 mL) was added a solution of 2.0M borane-methyl sulfide complex in tetrahydrofuran (91 mL, 181 mmol). The mixture was heated to reflux for 4.5 hours then allowed to stir overnight at room temperature. Methanol was added slowly to react with unreacted borane-methyl sulfide complex, which resulted a violent evolution of gas. When this subsided, excess methanol was added and the solution heated to reflux. After 2 hours the solution was cooled, the solvent evaporated under vacuum, and the residue triturated with ethyl acetate/hexane. An orange solid was filtered off which was rinsed with hexane, to yield 6-nitro-3,4-dihydro-2H-benzo[1,4]oxazine as a solid product. More of the solid was recovered as a second crop from the filtrate.

Provenance & Evidence