5,8-difluoro-2H-1-Benzopyran synthesis

Yield:457628-37-4 29%

Reaction Conditions:

with N,N-diethylaniline at 225; for 6 - 8 h;

Steps:

27.b

b) 5, 8-Difluoro-2H-chromene. 2, 4-Difluoro-2-propynyloxybenzene (20 g, 0.12 mol) was dissolved in N, N,-diethyl aniline (100 ml) and heated under argon atmosphere at 225 deg. Celcius with an oil- bath for 6-8 h. Ether (150 ml) was added and the aniline was removed by extraction using 2 M HO (aq). Purification by chromatography (silica gel, n-hexane) gave 5,8- difluoro-2H-chromene 5.8 g (29 %)

References:

WO2005/66131,2005,A1 Location in patent:Page/Page column 62-63