8-FLUORO-5-METHYLCHROMAN-4-ONE synthesis

Yield:942195-99-5 100%

Reaction Conditions:

with polyphosphoric acid at 100; for 2 h;

Steps:

13.1.2

STEP 1-2: 8-Fluoro-5-methyl-2,3-dihydro-4H-chromen-4-one A mixture of 3-(2-fluoro-5-methylphenoxy)propanoic acid (2.45 g, 12.4 mmol, STEP 1-1) in polyphosphoric acid (35 g) was stirred at 100° C. for 2 hours. After cooling to room temperature, the mixture was diluted with water (150 mL), and extracted with ethyl acetate (60 mL*2). The organic layers were combined, washed with brine, dried over magnesium sulfate, and concentrated in vacuum to afford the title compound as a white solid (2.30 g, quant.). ¹H NMR (CDCl₃, 270 MHz) δ: 7.15 (dd, J=9.9, 8.6 Hz, 1H), 6.73 (dd, J=8.6, 5,3 Hz, 1H), 4.59 (t, J=6.6 Hz, 2H), 2.85 (t, J=6.6 Hz, 2H), 2.59 (s, 3H) ppm.

References:

US2007/142448,2007,A1 Location in patent:Page/Page column 37