134997-74-3

A degassed suspension was prepared from 6-bromo-2H-1,4-benzoxazin-3(4H)-one (8.39 g), zinc cyanide (3.46 g) and tetrakis(triphenylphosphine)palladium (2.13 g) in DMF (70 mL). The suspension was reacted in an oil bath at 80 °C with stirring overnight. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently poured into water (500 mL). The precipitate was collected by diafiltration, air dried and washed with pentane. The resulting solid was dissolved in a solvent mixture of dichloromethane/methanol (1:1), filtered through a pad of silica gel, and the filtrate was concentrated to give the yellow solid product 3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazine-6-carbonitrile (5.68 g, 89% yield). Mass spectrometric detection showed [MH]+ = 175.

[1] Patent: WO2008/63667, 2008, A1. Location in patent: Page/Page column 69
[2] Patent: WO2008/63669, 2008, A1. Location in patent: Page/Page column 72
[3] Patent: WO2008/63671, 2008, A2. Location in patent: Page/Page column 174