Metal-free synthesis of primary amides from aldehydes using hydroxylamine-O-sulfonic acid

Primary amides are important organic compounds that are widely used in pharmaceuticals and materials science and serve as useful building blocks in organic synthesis. However, their efficient synthesis remains challenging. In this study, we report a direct, efficient, and metal-free method for the synthesis of primary amides from aldehydes via a nitrile intermediate using commercially available hydroxylamine-O-sulfonic acid (HOSA). This method is applicable to a broad range of substrates, affording the corresponding amides in good to high yields. Notably, most of the amides were purified simply by passing the crude product through a short silica gel plug.