SYNTHESIS OF N-[C-13]-METHYL-L-DOPA

The radiochemical synthesis of N-[C-11-methyl]-L-DOPA was accomplished by N-methylation of the methyl and ethyl esters of L-N-tert-butyl-oxycarbonyl-[beta-(3,4-dimethoxyphenyl)] alaninate with [C-11]iodomethane using sodium hydride in tetrahydrofuran and deprotection of the N-methyl intermediate with hydriodic acid. A catalytic influence of Kryptofix on the methylation reaction was observed. Using the ethyl ester precursor, the average specific activity at the end-of-synthesis was 972 mCi/mumole. The synthesis was completed in an average of 45 minutes following the end-of-bombardment.