Copper(ii)-catalysed direct C3–H esterification of indoles assisted by an N,N-bidentate auxiliary moiety

Abstract

The regioselective direct C3-esterification of indoles with OXA is developed in an efficient reaction with carboxylic acids using the catalyst CuBr₂ and oxidants Ag₂CO₃ and K₂S₂O₈. The simple experimental procedure is proved to be broadly applicable to a range of substrates, including aromatic and aliphatic acids, and the corresponding products were obtained in good yields up to 87%. At the same time, it provides a valuable approach to produce C3-benzyl derivatives of indoles through reaction with benzyl carboxylic acid under the same reaction conditions.