Malic Acid as a Green Catalyst for the N-Boc Protection under Solvent-free Condition

A protocol for the Chemoselective N-Boc protection of various types of amines has been developed. This includes heteroaryl, aliphatic, and alicyclic amines. The process makes use of malic acid as a catalyst and operates efficiently at ambient temperature without the need for solvents. This technique has been proven to effectively protect a wide range of functionalized amines containing both electron-donating and electron-withdrawing substituents. The benefits of this method include its fast reaction rate, high selectivity, excellent yield, catalyst recyclability, and environmentally friendly conditions.