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.