Synthesis and characterization of novel biologically active boron-containing analogues of capsaicin

Abstract

The anti-microbial and anti-cancer activities of the natural product capsaicin and related amides are of growing interest to medicinal chemists. Similarly, boron-containing compounds have been shown to have potent biological properties, with four boron-containing pharmaceuticals currently available on the market. As such, a number of boron-containing capsaicin analogues were generated for future biological testing and are discussed herein. Imines were generated from the facile reactions of 3,4-dimethoxybenzaldehyde with Bpin-functionalized aniline derivatives. These imines were subsequently reduced to the corresponding amines using HBcat as a reducing agent. Finally, the amines were reacted with aliphatic acyl chlorides, readily affording the desired amides in moderate yields. All amides were characterized using 1H NMR, 13C{1H} NMR, and FTIR spectroscopy, as well as 11B NMR spectroscopy where applicable.