Selectivity of elemental fluorine towards l-tyrosine and l-α-methyltyrosine in acidic media and the syntheses of their [18F]3-fluoro and [18F]3,5-difluoro derivatives

Fluorinated derivatives of l-tyrosine and l-α-methyltyrosine (l-α-MT) are known to be useful tracers for medical imaging with positron emission tomography. Direct fluorination of l-tyrosine and l-α-MT with [18F]F2 in different acidic media show increases in the radio-chemical yield of the 3-fluoro isomers as the acidity of the reaction medium is increased. Lower radiochemical yields and increased production of the 3,5-difluoro isomers of the …