Lewis acid catalyzed Claisen rearrangement: Regioselective synthesis of oxygen, nitrogen, and sulfur heterocycles

Regioselective synthesis of pentacyclic heterocycles containing oxygen, nitrogen, and sulfur has been achieved in good to excellent yields by the sequential Claisen rearrangement of but-2-ynyl ethers and sulfides containing quinolone moiety. The substrates ethers and sulfides were prepared from 1-aryloxy-4-chlorobut-2-ynes with N-alkyl-4-hydroxyquinoline-2(1H)-ones.Key words: regioselectivity, [3,3] sigmatropic rearrangement, nucleophilicity of sulfur, aluminium chloride, heterocycles.