Synthesis of carbon-11 labelled glycine and the dipeptides L-phenylalanylglycine and L-leucylglycine

Carbon-11 labelled glycine has been prepared in 30 min by carboxylation of α-lithiomethylisocyanide with a radiochemical yield of 10–15%. After coupling with L -phenylalanine-N-carboxyanhydride and L -leucine-N-carboxyanhydride followed by HPLC purification, the corresponding dipeptides were obtained in 20 min with a radiochemical yield of 30–40%. Consequently, starting with 11 CO 2 , non carrier added L -phenylalanyl[1- 11 C]glycine and L -leucyl[1- 11 C]glycine in 0.1 N NaH 2 PO 4 were obtained in 50 min with a radiochemical yield of 3–6%. The radiochemical yield figures are not corrected for decay.