EFFICIENT SYNTHESIS OF LOSARTAN, A NONPEPTIDE ANGIOTENSIN-II RECEPTORANTAGONIST

A highly efficient, convergent approach to the synthesis of the angiot ensin II receptor antagonist losartan (1) is described. Directed ortho -metalation of 2-trityl-5-phenyltetraz ole provides the key boronic ac id intermediate 10 for palladium-catalyzed biaryl coupling with bromid e 5 obtained from the regioselective alkylation of the chloroimidazole 2. This methodology overcomes many of the drawbacks associated with p reviously reported syntheses.