Dimethylformamide → 3-Fluoro-5-[(1-methyl-1H-imidazol-2-yl)thio]benzonitrile

Participants

Reaction Conditions

Reaction Steps

A mixture of NaH (60%, 3.16 g, 79 mmol) in oil was rinsed with dry pentane by syringe (3×10 mL) and excess solvent removed under a steam of N2. Solid 2-mercapto-1-methylimidazole (9.03 g, 79 mmol) was added followed by 200 mL of DMF under ice-bath cooling which resulted in a vigorous evolution of gas. After 15 min, solid 3,5-difluorobenzonitrile (10.00 g, 71.9 mmol) was added and the resulting mixture stirred for 5 days at 60° C. After cooling to rt the mixture was diluted with 500 mL ether and 500 mL water. The resulting white solid was collected by filtration and triturated in 50 mL of boiling ethanol which after cooling to rt was collected by filtration and dried under high vacuum to provide 1.54 g (9%) of 3-fluoro-5-(1-methyl-1H-imidazol-2-ylsulfanyl)-benzonitrile: 1H NMR (500 MHz, DMSO-d6): δ 3.54 (s, 3H), 7.40 (d, 1H, J=2 Hz), 7.52 (d, 1H, J=2 Hz), 7.96 (dt, 1H, J=8, 2 Hz), 8.13 (m, 1H), 8.15 (dt, 1H, J=8, 2 Hz); LCMS (m/z): 234.1 [C11H8FN3S+H]+. The ether layer was separated from the filtrate and washed with water, brine, dried (MgSO4) and evaporated. The residue was recrystallized from 30 mL of boiling ethanol to provided after filtration and drying a further 1.57 g (9%) which by HPLC was 75% enriched in 3-fluoro-5-(1-methyl-1H-imidazol-2-ylsulfanyl)-benzonitrile. The filtrate was evaporated to provide 5 g of crude product enriched in the title compound. This was adsorbed to 15 g of SiO2 from CH2Cl2 and subjected to MPLC on a 120 g column of SiO2 eluting with % EtOAc in hexanes (time): 35% (10 min), 35-50% (5 min ramp), 50% (20 min) which provided 1.2 g (7%) of 90% HPLC pure title compound as well as 1.96 g (12%) of 98% HPLC pure title compound: 1H NMR (500 MHz, DMSO-d6): δ 3.66 (s, 3H), 7.20 (d, 1H, J=1 Hz), 7.22 (ddd, 1H, J=8, 3, 2 Hz), 7.34 (t, 1H, J=2 Hz), 7.55 (d, 1H, J=1 Hz), 7.72 (ddd, 1H, J=8, 3, 2 Hz); LCMS (m/z): 234.1 [C11H8FN3S+H]+.

Provenance & Evidence