Synthesis of N‐(3‐azido‐4‐chlorophenyl)‐N′‐[3H‐methyl] thiourea, an efficient photoaffinity probe for the urea carrier

Abstract

AbstractStarting from commercial 4‐chloro‐3‐nitroaniline, through a 5 step synthesis, was prepared 3‐azido‐4‐chlorophenylisothiocyanate 5 which was reacted with [3H]‐methylamine. The latter was obtained by three methods: [3H]‐LiAlT4 reduction of benzylcarbamate gave rise to [3H]‐methylamine (S.A.: >70 Ci/mmol). Catalytic reduction of HCN with 3H2 lead to [3H]‐CH3NH2 (S.A.: 0.7 Ci/mmol). Schmidt rearrangement of [3H]‐sodium acetate gave [3H]‐CH3NH2 (S.A.: 29 Ci/mmol). Compound 7 at the highest specific activity had a self radiolysis rate precluding its practical use in biological studies whilst 29 Ci/mmol [3H]‐7 was satisfactory.