Synthesis of a carbon‐14 labeled 1‐(indole‐6‐carbonyl‐D‐phenylglycinyl)‐4‐(1‐methylpiperidin‐4‐YL)piperazine‐[carbonyl‐¹⁴C], LY517717‐[¹⁴C], a factor Xa inhibitor

Human Factor Xa is a trypsin‐like serine protease, which serves a critical role in blood coagulation events. LY517717 is currently under clinical investigation as a Factor Xa inhibitor. To support the ADME studies, LY517717 was synthesized using D ‐phenylglycine with a carbon‐14 labeled carboxyl moiety. This key component, D ‐phenylglycine‐[carboxyl‐ 14 C], was synthesized by a Strecker synthesis on benzaldehyde with potassium [ 14 C]cyanide, followed by a resolution of DL ‐phenyl‐glycine methyl ester‐[carbonyl‐ 14 C] with (+)‐tartaric acid in the presence of benzaldehyde.