A facile synthesis of N-benzyl-4-acetylproline via a tandem cationic aza-Cope rearrangement-Mannich reaction

N-Benzyl-4-acetylproline can be prepared from N-(2-hydroxy-2-methyl)but-3-enyl-N-benzylamine and glyoxylic acid via a tandem cationic aza-Cope rearrangement-Mannich reaction. This reaction represents the first example of such a mechanism being utilised for the synthesis of functionalised proline derivatives. In addition the reaction requires only mild conditions and a good yield of amino acid product is obtained without any need for purification.