Asymmetric Synthesis of 3,4,6‐Trisubstituted 2,5‐Diketopiperazines by Using Dynamic Kinetic Resolution of α‐Bromo Tertiary Acetamides

A new and efficient method for the asymmetric synthesis of 3,4,6-trisubstituted 2,5-diketopiperazines has been developed. The dynamic kinetic resolution of L-amino-acid-derived α-bromo tertiary amides in the nucleophilic substitution reaction with p-anisidine and a subsequent deprotection-cyclization process provides rapid access to diverse cis-2,5-diketopiperazines 5a–5o and proline-containing trans-2,5-diketopiperazines 5p–5t in enantiomerically pure form in 45–67 % overall yields.