International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes 1991-01-01

Oxidation of substituted 4-fluorobenzaldehydes: application to the no-carrier-added syntheses of 4-[18F]fluoroguaiacol and 4-[18F]fluorocatechol.

P K Chakraborty, M R Kilbourn

Index: Int. J. Rad. Appl. Instrum. A. 42(7) , 673-81, (1991)

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Abstract

The synthesis of 4-[18F]fluoroguaiacol (4-[18F]fluoro-2-methoxyphenol) has been achieved in no-carrier-added form starting from 2-methoxy-4-nitrobenzaldehyde, using nucleophilic aromatic substitution by [18F]fluoride followed by Baeyer-Villiger oxidation of the benzaldehyde to the phenol. Demethylation with boron tribromide gave 4-[18F]fluorocatechol (1,2-dihydroxy-4-[18F]fluorobenzene) with an overall yield of 18-28% (EOB) in less than 2 h synthesis time. The fluorine-18 labeled intermediates and products were identical to standards of 4-fluoroguaiacol and 4-fluorocatechol prepared by the same methods. This represents a new approach to the synthesis of fluorinated phenols in fluorine-19 and fluorine-18 forms.