SYNTHESES OF ISOTOPICALLY LABELED ANGIOTENSIN-II RECEPTOR ANTAGONIST GR138950X

Syntheses of [C-13] and [C-14]-labelled versions of angiotensin II rec eptor antagonist GR138950X, labelled in the imidazole carboxamide resi due, are described. These involved preparation of an iodoimidazole sub strate by a novel iododecarboxylation procedure, followed by cyanation with a mixture of carbon-labelled potassium cyanide and copper (I) io dide in DMF at high temperature. The preparation of a mass-labelled (M +5) version of GR138950X is also described. This involved the synthesi s of an [C-13(3), N-15(2)]-labelled imidazole from a 1,2,3-tricarbonyl compound, C-13(3)]propionaldehyde and [N-15]ammonia. The labelled imi dazole was further elaborated into multiply-labelled GR138950X.