Hydroxylamine‐O‐Sulfonic Acid (HOSA): A Recent Synthetic Overview

Abstract Hydroxylamine‐ O‐ sulfonic acid has been used as a versatile nitrogen source in synthetic organic chemistry. It has dual function and utilized both as a nucleophile and an electrophile during different synthetic transformations. This reagent is stable and easy to handle in both aqueous and organic solvents. It can be used with different functional groups under mild reaction conditions, making its widely applicable for constructing complex molecules. It has been utilized for various applications such as agrochemicals, pharmaceuticals, and polymer industries in the formation of S−N, C−N, O−N, and N−N bonds, as well as for efficient cyclization reactions under metal‐free conditions with excellent stereo– and regioselectivity. The present review provides a brief overview of all the advancements made in the past two decades using hydroxylamine‐ O‐ sulfonic acid as a nitrogen source.