4-Nitrobenzoic Acid → Triphenylphosphine Oxide

Participants

Reaction Steps

To (1R,2S)-2-benzimidazol-1-yl-1-methyl-propanol (1.27 g, 6.68 mmol), triphenylphosphine (1.19 g, 1.1 equiv), and 4-nitrobenzoic acid (1.22 g, 1.1 equiv) in THF (20 mL) was added diethyl azodicarboxylate (1.15 mL, 1.1 equiv). After stirring 12 h, the solvent was removed, and chromatographed on silica gel eluting with ethyl acetate to give the intermediate 4-nitrobenzoate and triphenylphosphine oxide as a mixture. This mixture was directly hydrolyzed with 1.0N sodium hydroxide (20 mL) in THF/methanol for 3 h. The solvent was partially removed and the reaction diluted with water and extracted with ethyl acetate. The crude product was chromatographed on silica gel eluting with 7%(8:1, ethanol/ammonium hydroxide) in dichloromethane. (1S,2S)-2-benzimidazol-1-yl-1-methyl-propanol was isolated as a colorless solid 552 mg (44%). 1H NMR (CDCl3) 8.00(s,1H), 7.69(d,1H), 7.43(d,1H), 7.24(M, 2H), 4.36(m,1H), 4.27(m,1H), 1.33(d,3H), 1.22(d,3H).

Provenance & Evidence