Three steps in one pot: synthesis of linear bilateral extended 2,2':6',2″-terpyridineruthenium(II) complexes

Metal complexes of linear bilateral extended 2,2':6',2″-terpyridine [2,6-bis(2-substituted furo[2,3-c]pyridin-5-yl)pyridine] are topological tridentate analogues of 5,5'-functionalized 2,2'-bipyridine. The present methodology provides access to linear bilateral extended 2,2':6',2″-terpyridineruthenium(II) complexes starting from 5,5″-bis(methoxymethoxy)-4,4″-bis(substituted ethynyl)-2,2':6',2″-terpyridines via one-pot cleavage of the methoxymethyl (MOM) protecting group, cycloisomerization, and metal complexation in the presence of Ru(DMSO)4Cl2. In this reaction, ruthenium(II) likely plays a triple role, acting as a Lewis acid to cleave the MOM ether, a catalyst facilitating 5-endo-dig cyclization, and a coordination metal center, being an integral part of the final product.