Triethylamine → 6-Fluoro-3-methyl-1,2-benzoxazole

Reaction equation

[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=O)[CH3:9])=[C:4]([OH:11])[CH:3]=1.C(N1C=CN=C1)([N:14]1C=CN=C1)=O.C(N(CC)CC)C>O1CCCC1>[F:1][C:2]1[CH:7]=[CH:6][C:5]2[C:8]([CH3:9])=[N:14][O:11][C:4]=2[CH:3]=1

Participants

Procedure

A mixture of 4′-fluoro-2′-hydroxyacetophenone, oxime (47.0 g, 0.278 mol) in tetrahydrofuran is heated to just under reflux, treated with a solution of 1,1′-carbonyldiimidazole (55.0 g, 0.340 mol) and triethylamine (39.0 g, 0.390 mol) in tetrahydrofuran, refluxed for one hour, cooled, concentrated in vacuo, and poured into an ice-water mixture. The resultant aqueous mixture is extracted with ether. The organic extracts are combined, washed sequentially with saturated ammonium chloride solution and brine, dried over anhydrous magnesium sulfate, and concentrated in vacuo to obtain an oil. Column chromatography of the oil using silica gel and a methylene chloride/hexanes solution (1:1) gives the title product as a yellow oil which is identified by 1H NMR spectral analysis.