SYNTHESIS AND EPR INVESTIGATIONS OF FLUOROCATECHOLAMINES

The synthesis of 3-fluoro- and 5-fluoronoradrenaline (3- and 5-fludron orepinephrine) starting from 4-fluorophenol or 3-fluoroanisole is desc ribed. In the first step the second OH group Is introduced followed by O-methylation and subsequent introduction of an acetyl function by Fr iedel-Crafts acylation. Replacement of one acetyl proton by bromine an d reaction with potassium phthalimide yields the adrenalone-type compo unds. After cleavage of the methyl ethers and hydrazinolysis of the am ide function the catecholamines were obtained by reduction of the carb onyl group. Oxidation of the catechols obtained by the reduction leads to the corresponding semiquinone radicals which gave rise to well res olved EPR and, in some cases, ENDOR spectra. An assignment of the data obtained could be made by comparison of the variety of radicals inves tigated and with the help of multiresonance experiments. The 5-fluoro- o-benzosemiquinones are less stable than the 3-fluoro-radicals as can be seen by the formation of paramagnetic secondary products.