Synthesis of 2 C-14 labeled cathepsin C inhibitors: The use of a cyanide to displace a Benzotriazole.

In support of the development of a new treatment for COPD, 2 C-14 labeled compounds were required for in vitro animal studies. The synthesis of nitrile [ C]-1 was completed in 3 steps from C-14 labeled 4-bromobenzonitrile in accord with the previously developed medicinal chemistry route. The second compound, 2, did not possess an arylnitrile as did 1, which made the synthetic design more complex. An advanced, unlabeled benzotriazole containing intermediate, 10, was synthesized in low yield over 3 steps and was subsequently reacted with K CN to give a mixture of diastereomers 12. Separation of the diastereomers followed by deprotection afforded [ C]-2 in a 13% radiochemical yield.