對烯烴或炔烴的加成,是合成氟代烴最直接的方法。由於F2和HF的使用不便以及反應放熱嚴重,難以控制,限制了其在有機合成中的應用,但在工業上應用較多。
多種氟代試劑都能對烯烴加成,生成鄰二氟代烷烴。
而單氟代烷烴則是通過HF對烯烴的加成製備,反應遵循Markovnikov規則。由於操作和控制不方便,一個替代方法是使用Olah試劑(HF/Pyridine)。
【Olah, G, A; Welch, J,T. J. Org. Chem. 1979, 44, 3872】
Olah試劑對炔烴的加成則生成二氟代烷烴。
【Olah, G, A; Welch, J,T. J. Org. Chem. 1979, 44, 3872】
AcOF, CF3OF,FOClO3,和CsSO4F等試劑對烯烴的加成會引入另一個官能團,得到鄰位取代的氟化物。
NO2BF4對烯烴加成得到鄰硝基氟化物,引入一個含氮官能團。
【 Mursakulov, I, G; Talybov, A, H. Chem.Abstr, 1979,90, 38561】
鄰滷氟化物可以通過不同試劑對烯烴的加成製得,如環己烯,在不同的條件下生成鄰氯,鄰溴和鄰碘的氟代環己烷。
a Olah, G, A; Welch, J, T. J. Org. Chem. 1979,44, 3872.
b Rozen, S; Brand, M. J. Org. Chem, 1985,50, 3342.
c Heasley, V. L;Gipe, R. K; Martin, J. L. J.Org. Chem. 1983, 48, 3195.
d Alvernhe, G; Laurent, A; Haufe, G. Synthesis.1987, 562.
e Schmidt, H; Mernert, H. Angew. Chem. 1960,72, 493.
1-Bromo-2-fluoro-2-phenylpropane. A magnetically stirred mixture of α-methylstyrene (7.1 g, 60 mmol), triethylamine trihydrofluoride and (14.7 mL, 90 mmol) and dichloro- methane (60 mL) contained in a 250 mL, single-necked, round-bottomed flask is treated with N-bromosuccinimide (11.8 g, 66 mmol)at0°C. After 15 min, the bath is removed, and stirring is continued at room temperature for 5 hr. The reaction mixture is poured into ice water (1000 mL), made slightly basic with aqueous 28% ammonia, and extracted withdichloromethane (4 × 150 mL). The combined extracts are washed with 0.1 Nhydrochloric acid (2 × 150 mL) and 5% sodium hydrogen carbonate solution (2 × 150 mL) and then dried over magnesium sulfate . After removal of the solvent by rotary evaporation, the crude product is distilled to give the product:11.6 g(89%); bp 50-52°C(0.15 mm), n20 D 1.5370
【Haufe, G; Alvernhe, G; Laurent,A. Organic Syntheses. Coll. Vol. 10, 128.】
References:
[1]《藥物合成反應》
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