Synthesis of [ 14 C]KT3‐671, 2‐Propyl‐8‐oxo‐1‐[ (2′‐(1H‐[ 14 C] tetrazole‐5‐yl) biphenyl‐4‐yl) methyl]‐4,5,6, 7‐tetrahydro‐cycloheptimidazole, a novel potent nonpeptide angiotensin II receptor antagonist

2‐Propyl‐8‐oxo‐1‐[(2′‐(1H‐tetrazole‐5‐yl) biphenyl‐4‐yl)methyl]‐4, 5, 6, 7‐tetrahydrocyclohept imidazole (KT3‐671), which has been found to be a potent and selective angiotesin II receptor antagonist, was synthesized in 14 C‐labelled form by using potassium[ 14 C]‐cyanide. [ 14 C](KT3‐671) 9 with a specific activity of 1.74GBq/mmol was prepared in four steps in 29.8% overall radio‐chemical yield from potassium[ 14 C]‐cyanide.