Lithium Perchlorate‐Catalyzed Boc Protection of Amines and Amine Derivatives

A new mild and chemoselective method for mono‐ N ‐protection of amines and amine derivatives as tert ‐butoxycarbonyl derivatives is reported. The reaction proceeds with lithium perchlorate (20 mol %) and pyrocarbonates, and shows general applicability. The catalytic action of LiClO 4 is specific for the activation of Boc 2 O, thus acid‐sensitive functionalities of the starting materials remain unchanged in the protection process. This procedure works well for sterically hindered primary amine as well as electron‐deficient primary arylamines, primary and secondary amino alcohols, α‐amino acid esters, hydroxylamines, hydrazines and sulfonamides.