Solvent-free and eco-friendly green protocol for N-Boc Protection of amines using picric acid as a catalyst

We have developed an environmentally conscious green protocol to protect amine functional groups in drug discovery and the total synthesis of biologically active natural products. This method utilizes di-tert-butyl dicarbonate ((Boc)₂O) to protect aromatic and aliphatic amines, with readily available picric acid (2 mol%) serving as a Brønsted acid catalyst. This approach enables rapid and high-yield (up to 98 %) protection of amines under completely solvent-free and eco-friendly conditions, thereby promoting a cleaner and more sustainable synthetic process.