Diethylamine → 4-cyano-N,N-diethyl-2-fluoro-benzamide

Participants

Reaction Steps

To 4-cyano-2-fluoro-benzoic acid (2.0 g, 12.1 mmol) in DMF (18 mL) at room temperature was added N-ethylethanamine (1.5 g, 2.1 mL, 13.3 mmol) followed by 0-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (4.6 g, 12.1 mmol) and diisopropylethylamine (3.9 g, 5.3 mL, 30.3 mmol) and the reaction mixture was stirred for 3 hours. The reaction mixture was diluted with EtOAc and washed with brine solution. The organics were separated, dried and concentrated in vacuo. The residue was purified by silica gel column chromatography using EtOAc-DCM (10-100%) as eluent to give 4-cyano-N,N-diethyl-2-fluoro-benzamide (2.0 g, 75%). 1H NMR (400 MHz, CDCl3) δ 7.51 (dd, J=7.8, 1.3 Hz, 1H), 7.47-7.37 (m, 2H), 3.56 (q, J=7.0 Hz, 2H), 3.16 (q, J=7.1 Hz, 2H), 1.24 (td, J=7.1, 2.0 Hz, 4H). To 4-cyano-N,N-diethyl-2-fluoro-benzamide (1.75 g, 7.9 mmol) was added a 2:1 mixture of THF:MeOH (15 mL), followed by 4 N NaOH solution (10 mL, 39.6 mmol) and the reaction mixture was heated at 65° C. for 2.5 hours. The reaction mixture was cooled, diluted with EtOAc and washed with 2 M HCl solution. The organics were separated, dried and concentrated in vacuo to give 4-(diethylcarbamoyl)-3-fluoro-benzoic acid (1.91 g, 66%) as a solid. ESI-MS m/z calc. 239.24. Found 240.2 (M+1); Retention time: 0.99 minutes (3 min run).

Provenance & Evidence