Radiosynthesis of O-[11C]methyl-L-tyrosine and O-[18F]Fluoromethyl-L-tyrosine as potential PET tracers for imaging amino acid transport

Two positron-emitting analogues of tyrosine, O-[11C]methyl-L-tyrosine and O-[18F]fluoromethyl-L-tyrosine were prepared as new tumor imaging agents. The alkylating agent, [11C]methyl triflate or [18F]fluoromethyl triflate, was simply bubbled through a dimethylsulfoxide solution of L-tyrosine disodium salt at room temperature. After subsequent HPLC purification the labeled L-tyrosine analogues were obtained in decay-corrected radiochemical yields of over 50%, based on their corresponding labeling agent, with radiochemical purities always higher than 98%. The quite straightforward preparation, together with the high radiochemical yields achieved, make both these syntheses suitable for routine production. Copyright © 2003 John Wiley & Sons, Ltd.