Mild chemoselective acylation of amines with a reusable amino-grafted mesoporous catalyst

M. SOLEDAD LEGNOVERDE; GUSTAVO ROMANELLI; ELENA I. BASALDELLA

Simposio; 3rd International Symposium Advanced Micro and Mesoporous Materials; 2009

 The acylation reaction of amines provides an efficient means for protecting an amino functionality in a multi-step synthetic process2-3. However, most of the reported methods suffer from one or more disadvantages like long reaction time, harsh reaction conditions, the occurrence of side reactions, toxic reagents, poor yields of the desired products and intolerance of other functional groups13. In recent years a great interest was developed in the reactions performed under heterogeneous catalysis. In this article we report the use of amino-grafted SBA-15 as an efficient catalyst for the selective acetylation of amines.  For instance, the treatment of aniline with acetic anhydride in the presence of 50 mg of amino grafted SBA-15 in toluene at room temperature, afforded the acetylated compound in 94% yield.    In similar manner, various substituted alcohols, phenols and thiol were put under to a same protocol. Alcohols, phenols and thiols no react under the identical reaction conditions. Thus, by taking advantage of the differential reactivity between nucleofiles, we were able to carry out chemoselective acetylation of amines over alcohols, phenols and thiols.  This method has the advantages of simplicity in operation and mild reaction conditions (room temperature), low cost, very good yields, and environment friendliness compared to homogeneous catalysis procedures. Moreover, this procedure introduces a  practical and viable technology for the acetamides synthesis.