三苯基膦/咪唑/碘体系碘代反应

三苯基膦、咪唑、碘体系进行碘代反应，三者一般1eq-1.5eq。溶剂用的有：二氯甲烷，甲苯，四氢呋喃，乙腈和乙醚，反应的时候最好避避光，反应要求无水。通常情况下反应温度低，反应时间短，产率高，另外有些底物是需要加热才能反应。

反应机理

反应实例

To dry dichloromethane (4 mL) was added in order: triphenylphosphine (1.2~1.5 mmol), imidazole (1.2~1.5 mmol) and iodine (1.2~1.5mmol). A solution of the alcohol (1.0mmol) in dry dichloromethane (1 mL) was added and the mixture was stirred at room temperature under argon for 0.5~3.0 h. The disappearance of the alcohol and formation of the alkyl iodide wasfollowed by TLC. When the reaction wascomplete, most of the solvent was removed in vacuo and the product waspurified by passing it through a column of silica gel with pentane as solvent.

【Synthetic. Communications, 1990, 20, 10, 1473-1479】

Iodine (2.72 g, 10.7 mmol) was added in portions to a mixture of the alcohol(1.00 g, 5.14 mmol, finelypowdered), triphenylphosphine (3.02 g, 11.5 mmol) and imidazole (1.59 g, 23.3 mmol) in toluene-acetonitrile (2:1 60 mL)stirred at 90oC. After 2h themixture was cooled to room temperature. Water (50 mL) and toluene (20 mL) were added to the mixture which wasthen shaken vigorously and transferred to a separating funnel. The organic phase was extracted with wateruntil only triphenylphosphine and triphenylphosphine oxide remained in theorganic phase. The combined aqueousphase was washed with a small amount of toluene and then concentrated. The residue was acetylated with aceticanhydride and pyridine at room temperature. When the acetylation was complete, the reaction mixture was concentratedand the residue dissolved in toluene. The toluene solution was extracted with water in water in order toremove imidazole impurities, dried and concentrated. The product was purified by chromatography ona short silica gel column to yield compound (1.41 g, 63%).

【 J. C.S., Perkin Trans. 1, 1982, 681-683】