Hydrochloric Acid → 7-benzenesulfonyl-3,4-dihydro-2H-benzo[1,4]oxazine

A suspension of 7-benzenesulfonyl-4H-benzo[1,4]oxazin-3-one (2.314 g., 8.00 mmol) in 30 ml anhydrous THF was brought to reflux, and borane-dimethyl sulfide complex (2.4 mL, 10 M solution) was added dropwise via syringe. The solution was refluxed for two hours, at which time the solution was cooled to room temperature and ethanolic HCl (10 mL., 2 N solution) was added dropwise. The resulting solution was refluxed for 3 hours and allowed to cool to room temperature. The reaction mixture was poured into 100 mL water, the resulting solution made basic with potassium carbonate and extracted three times with 50 mL Et2O. The organic fractions were washed with 100 mL brine, dried over Na2SO4 and concentrated in vacuo. The resulting residue was purified by flash chromatography (20 to 50% EtOAc in hexanes) to give 1.75 g of 7-benzenesulfonyl-3,4-dihydro-2H-benzo[1,4]oxazine (79.5%) as a yellow solid. MS: 276 (M+H)+.

1. temperatureto reflux
2. additionborane-dimethyl sulfide complex (2.4 mL, 10 M solution) was added dropwise via syringe
3. temperatureThe solution was refluxed for two hours, at which time the solution
4. temperatureThe resulting solution was refluxed for 3 hours
5. temperatureto cool to room temperature
6. extractionextracted three times with 50 mL Et2O
7. washThe organic fractions were washed with 100 mL brine
8. dry with materialdried over Na2SO4
9. concentrationconcentrated in vacuo
10. customThe resulting residue was purified by flash chromatography (20 to 50% EtOAc in hexanes)

ORD record

ord-d782737fc5bf4216992b05230f1594fb

Source dataset

uspto-grants-2008_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07378415B2