7-Nitro-3,4-dihydro-1,4-benzoxazepin-5(2H)-one synthesis

Yield:21228-43-3 43%

Reaction Conditions:

with potassium nitrite;sulfuric acid at 0 - 20; for 4.5 h;

Steps:

9.iii

3,4-Dihydro-l,4-benzoxazepin-5(2H)-one (15 g, 92 mmol) was dissolved in concentrated sulfuric acid and the mixture was cooled to O⁰C. Potassium nitrite (10.4 g, 103 mmol) was added portionwise. The mixture was stirred at 0°C for 30 min and at room temperature for 4 h. The mixture was poured onto ice (1000 ml) and the solid formed was collected by filtration. The solid was suspended in boiling EtOAc and then cooled to RT. The solid was collected by filtration to give the title compound (8.21 g, 43%). MS ESI m/z M-I-H⁺ 209; M-H⁺ 207.

References:

WO2007/4959,2007,A1 Location in patent:Page/Page column 35