Synthesis of (2‐mercaptoacetyl)‐L‐[2‐ 14 C]tryptophan as a selective metallo‐β‐lactamase inhibitor via [2‐ 14 C]indole based on chiral pool strategy

Metallo‐beta‐lactamase enzymes make bacteria resistant to a broad range of commonly used beta‐lactam antibiotics. Several thiol derivatives of L‐amino acids have been shown their inhibitory effects against the metallo‐β‐lactamase IMP‐1. In this study, (2‐mercaptoacetyl)‐L‐tryptophan as a new inhibitor of metallo‐β‐lactamases labeled with carbon‐14 in the 2‐position of the indole ring was prepared from [2‐ 14 C]indole as a key synthetic intermediate based on chiral pool strategy. The overall synthesis was performed in 10 steps with the overall radiochemical yield 3.6% on the basis of the barium [ 14 C]carbonate as a starting material.