Aromatic Fluorinations Suitable for Fluorine-18 Labeling of Estrogens

Two aromatic fluorination methods, the decomposition of aryl azides and the decomposition of aryltriazenes, were investigated as methods potentially suitable for fluorine-18 labeling of estrogens. The aryltriazene method gives moderate yields in many systems but fails with o-methoxy or (methanesulfonyl) oxy groups. The aryl azide method gives good yields of p-fluoroanilines, which can be deaminated readily, but oxygen or large alkyl groups ortho to the azide interfere with the fluorination. The synthesis of m-fluorohexestrol via the aryltriazene decomposition approach is reported.