Reaction of Functionalized Anilines with Dimethyl Carbonate over NaY Faujasite. 3. Chemoselectivity toward Mono-N-methylation

Abstract

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).