Bio-Based Amides from Renewable Isosorbide by a Direct and Atom-Economic Boric Acid Amidation Methodology

The functionalization of bio-sourced isohexides has proved challenging over the last number of years, especially in polymer and medicinal chemistry. We report herein the synthesis of bio-based amido-isohexides by the known boric acid catalysed amidation reaction. The coupling reaction was successfully performed with aliphatic and aromatic carboxylic acids. The extension of the scope of the reaction to eight Boc-protected amino acids is also described, the products being obtained in moderate to good yields. A preliminary screening of these new potential organocatalysts was carried out for the aldolization of isatin.