Synthesis of iodine-125 labelled analogues of metyrapone and metyrapol

Metyrapone (1) and metyrapol (2) are potent and reversible inhibitors of the 11β-hydroxylase enzyme system of the adrenal cortex. Iodine-125-labelled derivatives of 1 and 2 were required for biodistribution studies. Utilizing a new exchange procedure these radioiodinated analogues were synthesized with radiochemical yields ranging from 24-100% and specific activities as high as 1.72 Ci/mmol.