3,5-DIFLUORO-4-FORMYLBENZONITRILE, 97% synthesis

Yield: 98%

Reaction Conditions:

with sulfuric acid in tetrahydrofuran at 20; for 72 h;

Steps:

B.(ii) (ii) 2,6-Difluoro-4-formylbenzonitrile
2,6-Difluoro-4 [ (methylsulfinyl) (methylthio) methyl] benzonitrile (2.17 g, 8.32 mmol; see step (i) above) was dissolved in 90 mL of THF and 3.5 mL of concentrated sulfuric acid was added. The mixture was left at room temperature for 3 days and subsequently poured into 450 mL of water. Extraction three times with EtOAc followed and the combined ethereal phase was washed twice with aqueous sodium bicarbonate and with brine, dried [(NA2SO4)] and evaporated. Yield: 1.36 g [(98%).] The position of the formyl group was established by 13C NMR. The signal from the fluorinated carbons at 162.7 ppm exhibited the expected coupling pattern with two coupling constants in the order of 260 Hz and 6.3 Hz respectively corresponding to an ipso and a meta coupling from the fluorine atoms. 'H NMR (400 MHz, [CDC13)] [8] 10.35 (s, 1H), 7.33 (m, 2H)

References:

ASTRAZENECA AB WO2003/101423, 2003, A1 Location in patent:Page 25