Bifunctional RuII-Complex-Catalysed Tandem C-C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents

Catalytic activities of a series of functional bipyridine-based Ru-II complexes in beta-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional Ru-II complex (3a) bearing 6,6'-dihydroxy-2,2'-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol%) dehydrogenative carbon-carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of beta-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal-ligand cooperative Ru-II system. Remarkably, complex 3a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction.