AbstractThe cobalt‐catalyzed direct C‐4 selective alkylation of quinolines is described. The reaction conditions used previously for pyridines were fully modified to achieve C‐4 selectivity in quinoline alkylation. Cobalt(II) acetate [Co(OAc)2] (2–4 mol%) in combination with butyllithium (BuLi) and pyridine was best, and C‐4 alkylation proceeded in 54–95% yield with C‐4/C‐2=>20:1–2.5:1 and branched/linear=>20:1 selectivity.magnified image
A photochemical benzylation of protonated quinolines was realized by single electron transfer (SET) to the excited state of the quinoline from the aromatic reactant. The benzylated product is formed by cross-coupling between the benzyl radical and the heterocyclic radical when they are in close proximity to one another. This allows the formation of products which are, to the best of our knowledge, unaccessible in other ways and which have now been obtained for the first time. (C) 2010 Elsevier B.V. All rights reserved.