Selva Maurizio, Tundo Pietro, Perosa Alvise
Dipartimento di Scienze Ambientali dell'Università Ca' Foscari, Calle Larga S. Marta 2137, 30123-Venezia, Italy.
J Org Chem. 2003 Sep 19;68(19):7374-8. doi: 10.1021/jo034548a.
In the presence of NaY faujasite, dimethyl carbonate (MeOCO(2)Me, DMC) is a highly chemoselective methylating agent of functionalized anilines such as aminophenols (1), aminobenzyl alcohols (2), aminobenzoic acids (3), and aminobenzamides (4). The reaction proceeds with the exclusive formation of N-methylanilines without any concurrent O-methylation or N-/O-methoxy carbonylation side processes. Particularly, only mono-N-methyl derivatives [XC(6)H(4)NHMe, X = o-, m-, and p-OH; o- and p-CH(2)OH; o- and p-CO(2)H; o- and p-CONH(2)] are obtained with selectivity up to 99% and isolated yields of 74-99%. DMC, which usually promotes methylations only at T > 120 degrees C, is activated by the zeolite catalyst and it reacts with compounds 1, 2, and 4, at 90 degrees C. Aminobenzoic acids (3) require a higher reaction temperature (> or =130 degrees C).
在NaY八面沸石存在下，碳酸二甲酯（MeOCO₂Me，DMC）是功能化苯胺（如氨基酚（1）、氨基苄醇（2）、氨基苯甲酸（3）和氨基苯甲酰胺（4））的一种高度化学选择性甲基化试剂。该反应仅生成N-甲基苯胺，不存在任何同时发生的O-甲基化或N-/O-甲氧基羰基化副反应。特别地，仅得到单-N-甲基衍生物[XC₆H₄NHMe，X = 邻、间和对-OH；邻和对-CH₂OH；邻和对-CO₂H；邻和对-CONH₂]，选择性高达99%，分离产率为74 - 99%。通常仅在T > 120℃时促进甲基化反应的DMC，被沸石催化剂活化，并且它在90℃下与化合物1、2和4反应。氨基苯甲酸（3）需要更高的反应温度（≥130℃）。
