Synthesis of 2‐amino‐5‐(1‐methyl‐5‐nitro‐[4‐3H]‐2‐imidazolyl)‐1,3,4‐thiadiazole

2-Amino-5-(1-methyl-5-nitro-4-iodo-2-imidazoyl)-1,3,4-thiadiazole (5) was prepared from imidazole via a 4-steps sequence. Reductive desiodination of 5 using a tetrahydrofuran solution of NaBH4 in the presence of tritiated water provided the title compound (specific radioactivity 12.6 Ci/mmol) in one step. © 1998 John Wiley & Sons, Ltd.