One‐pot synthesis of 1,3‐disubstituted imidazo[1,5‐a]pyridines via acceptorless dehydrogenative coupling of primary alcohols promoted by binuclear ruthenium(II) N^O‐chelating complexes

A simple, straightforward and atom economic strategy to the synthesis of 1,3‐disubstituted imidazo[1,5‐a]pyridines using binuclear ruthenium(II) catalyst through acceptorless dehydrogenative coupling of primary alcohols with 2‐benzoylpyridine has been presented. New binuclear arene Ru(II) N^O chelating complexes of common formula [(η 6 ‐benzene) 2 Ru 2 Cl 2 (μ‐L)], L = bis (furoylhydrazone) derivatives ( 1–3 ) were synthesized and characterized by analytical and spectral (FT‐IR, NMR and HR‐MS) techniques. The solid‐state molecular structure of one of the complexes (complex 1 ) has been authorized by single‐crystal XRD method. Further, a wide range of 1,3‐disubstituted imidazo[1,5‐a]pyridine derivatives have been successfully attained in good to excellent yields using binuclear arene Ru(II) catalysts with 1.0 mol% of catalyst loading. Further, control experiments unveil that the dehydrogenative coupling reaction mechanism proceeds via the formation of aldehyde and imine intermediates. The overall catalytic system releases H 2 and water as only valuable by‐products.