Acetic acid as a catalyst for the N-acylation of amines using esters as the acyl source

Abstract

We report a cheap and simple method for the acetylation of a variety of amines using catalytic acetic acid and either ethyl acetate or butyl acetate as the acyl source. Catalyst loadings as low as 10 mol% afforded acetamide products in excellent yields at temperatures ranging from 80-120 °C. The methodology can also be successfully applied for the synthesis of a broad range of other amides, including the formation of formamides at 20 °C.

A green chemistry perspective on catalytic amide bond formation

“…The use of trifluoroethanol to generate a reactive ester in situ via transesterification was reported by Watson & Jamieson 40 , and this mild protocol can be applied to a range of substrates, though a stoichiometric quantity of base is required, and large-scale reactions were not described. acid 44 . The latter is particularly interesting from a safety/sustainability perspective but it has yet to be widely explored.…”

Two different facile and efficient approaches for the synthesis of various N-arylacetamides via N-acetylation of arylamines and straightforward one-pot reductive acetylation of nitroarenes promoted by recyclable CuFe2O4 nanoparticles in water

“…Up to now, several methods have been reported for the mentioned reaction. Nevertheless, some of these methods along with some merits have one or more drawbacks such as the use of expensive and harmful reagents, solvents or catalysts, harsh reaction conditions, low yield of products and (or) lengthy reaction times and so on [77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96]. In this regard, we decided to introduce a simple, efficient, green, costand time-effective protocol for the N-acetylation of arylamines.…”

Direct synthesis of amides from nonactivated carboxylic acids using urea as nitrogen source and Mg(NO3)2or imidazole as catalysts

“…5,6,44,[56][57][58][59][60] Transamination [61][62][63][64] reactions to convert primary amides into more complex amides, and the acylation of amines to produce secondary amides are also important transformations reported in this eld. 65 The direct synthesis of secondary amides from nonactivated carboxylic acids is an important transformation that has been less exploited and studied. 57,64,66 Secondary and tertiary amides can be obtained by condensation of the acid and the amine, but the competing acid-base reaction makes this coupling challenging, overcome by forcing conditions.…”

“… 5 , 6 , 44 , 56 – 60 Transamination 61 – 64 reactions to convert primary amides into more complex amides, and the acylation of amines to produce secondary amides are also important transformations reported in this field. 65 …”