在Olah試劑（HF/pyridine）存在下，α-氨基酸的氨基在重氮化后被氟取代，生成α-氟代羧酸。高HF/pyridine比例(70/30)可能導(dǎo)致重排生成β-氟代羧酸，通常情況下使用的HF/pyridine比例為48/52。α-氨基酸酯也能發(fā)生同樣的反應(yīng)。
a. Olah, G, A. Prakas, K, B, S. Chao, Y, L. Hel. Chim. Acta.1981, 64, 2528.
b. Olah, G, A. Welch, J, T. Synthesis. 1974, 65.
c. Olah, G, A. Welch, J, T. J. Org. Chem. 1979,44, 3872.
反應(yīng)示例：
To the alanine (1.74 g, 20 mmol) in pyridinium polyhydrogen fluoride (50 mL) in polyolefin bottle with good stirring at 0oC was added NaNO2 (2.1 g, 30 mmol) in three prortions over aperiod of 30 min. Stirring was continued at room temperature for 5 h, then quenched with 100 mL of ice water and extracted with ether. The organic layer was washed with brine and dried over Na2SO4. The solvent was removed under reduced pressure, the residue was recrystallized to give the desired product (1.39 g, 76%)
【Olah, G, A. Prakas, K, B, S. Chao, Y, L. Hel. Chim. Acta.1981, 64, 2528】
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