Robust Ruthenium(II)-Catalyzed C-H Arylations: Carboxylate Assistance for the Efficient Synthesis of Angiotensin-II-Receptor Blockers

Ruthenium(II) complexes have emerged as effective catalysts for CH arylations of tetrazolyl-substituted arenes by chelation assistance. Particularly, bifunctional additives, such as carboxylates or phosphates, set the stage for versatile CH functionalizations with organic halides, which allowed for the step-economical synthesis of angiotensin-II-receptor blockers (ARBs) with unprecedented levels of efficacy and substrate scope. The outstanding robustness of the ruthenium(II) complexes was among others illustrated by remarkably low catalyst loadings and applications of this technology on a preparative scale.