6-chloro-3,4-dihydro-2h-pyrido[3,2-b][1,4]oxazine synthesis

Yield:1303587-97-4 75%

Reaction Conditions:

with potassium carbonate in acetonitrile;Reflux;

Steps:

14.4

To a solution of 3-amino-5-chloropyrazin-2-ol (62; 0.9 g, 6. 1 8 mmol) in CH3CN ( 1 00 mL) was added 1 ,2-dibromoethane ( 1 . 16 g, 6.1 8 mmol) and 2CO3 ( 1 .71 g, 1 2.37 mmol). The mixture was refluxed overnight. After cooling to room temp, the mixture was concentrated, dissolved in water and then extracted with EtOAc. The combined organic phase was concentrated and the residue was purified by silica gel chromatography to obtain 6-chIoro-3,4-dihydro-2H- pyrazino[2,3-b][ l ,4]oxazine (63; 0.8 g, 75% yield). MS (ESI) calcd for C₆H₆CIN₃0: 1 71 .58; found: 173 [M+H].

References:

WO2011/59839,2011,A1 Location in patent:Page/Page column 89-90