6-Nitro-3,4-dihydro-2H-1,4-benzothiazine, 97% synthesis

Yield:-

Reaction Conditions:

with borane-THF in tetrahydrofuran;Reflux;

Steps:

76

6-nitro-2H-benzo[b][1,4]thiazin-3(4H)-one (4 g, 19 mmol) was stirred in BH₃- THF (285 mL, 258 mmol) at reflux overnight. After this time the reaction mixture was cooled to rt and quenched with MeOH. The reaction was partitioned between EtOAc and water. The separated organic layer was dried over Mg₂SO₄ and evaporated in vacuo to give 6-nitro-3,4-dihydro-2H-benzo[b][1,4]thiazine that was used without further purification in the next step. Mass Spectrum (ESI) m/e = 197 (M + 1).

References:

WO2010/151737,2010,A2 Location in patent:Page/Page column 145