p-Toluenesulfonic acid → 1,3-Bis-(4-fluorobenzoyl)benzene thiosemicarbazone

Participants

Reaction Steps

1,3-bis-(4-fluorobenzoyl)benzene 12 (0.347 g, 1.08 mmol) was dissolved in anhydrous methanol (50 mL). The solution was heated at reflux for 15 min, and thiosemicarbazide (0.049 g, 0.54 mmol) and a catalytic amount of p-toluenesulfonic acid were added. After 10 h at reflux, the resulting solution was concentrated under reduced pressure. Purification using flash chromatography (silica gel, hexanes:ethyl acetate, 70:30) afforded the desired 1,3-bis-(4-fluorobenzoyl)benzene thiosemicarbazone (0.11 g, 0.278 mmol, 52% yield) as a white solid; 1H NMR (500 MHz, CDCl3): δ 8.67 (s, 1H, NH), 7.97 (m, 1H, ArH), 7.90 (m, 1H, ArH), 7.83 (m, 1H, ArH), 7.75 (m, 1H, ArH), 7.68 (m, 1H, ArH), 7.500 (m, 2H, ArH), 7.39 (s, 1H, NH2), 7.31 (m, 2H, ArH), 7.22 (ddd, J=8.5 Hz, 5.0 Hz, 3.0 Hz, 1H, ArH), 7.16 (ddd, J=8.5 Hz, 5.0 Hz, 3.0 Hz, 1H, ArH), 7.06 (ddd, J=8.5 Hz, 5.0 Hz, 3.0 Hz, 1H, ArH), 6.36 (s, 1H, NH2); HRMS (ESI) calculated for C21H15F2N3OSH (M+H)+ 396.0970, found 394.0834; HPLC retention time 13.740, 13.966 min.

Provenance & Evidence