福山机理B084——芳香酮在AgNO3-I2体系的氧化增碳羧化反应|氧化|甲酸|甲醇|甲醚|碘代|芳香酮

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概述：

碘和硝酸银作为氧化剂，一种芳香酮的氧化增碳羧化反应，反应中最应该知道的就是原甲酸三甲酯的作用：①产生甲醇，②除水。

同时有必要了解一下该反应的步骤：

Oxidation of l-Arylalkanones by Iodine-Silver Natrate. In a typical experiment iodine (10.5 mmol) was added to a suspension of silver nitrate (21.0 mmol) in a mixture of methanol (45 ml) and trimethyl orthoformate (15 ml), containing the appropriate ketone (10 mmol) ; the mixture was then heated under reflux for 5 h. After the solution had been cooled, the silver salts were filtered off, and the filtrate worked up in the same way as in the thallium(r1r) oxidations. In some reactions the temperature was maintained at ca. 20 "C throughout and in others the solvent was replaced by ethanol and triethyl orthoformate to obtain higher temperatures. In a few cases iodine was replaced by bromine as the oxidant. Larger scale reactions were carried out when it was desired to isolate pure samples of the rearranged ester.

J. Chem. Soc., Perkin Trans. 1 , 1982, 235-242

反应过程：

机理解读：
①原甲酸甲酯在酸性条件下解离出甲醇和羰基加成，脱除水得到钅羊盐，氢转移得到烯醇甲醚； ②烯醇甲醚和碘发生碘代反应；得到α-碘代钅羊盐； ③α-卤代钅羊盐和另一分子甲醇作用得到α-碘代缩醛； ④硝酸银和α-碘代缩醛作用，使得碘带着一堆电子离去，产生一个碳正离子（高中知识，碘化银沉淀↓）； ⑤苯环作为富电子物种和碳正离子作用，得到苯鎓离子； ⑥张力环开环，回复芳香性，得到钅羊盐（增碳）； ⑦钅羊盐和另一分子甲醇作用得到原甲酸酯； ⑧原甲酸酯水解得到羧酸酯产物，进一步可得到羧酸。