A new one-pot synthetic approach to the highly functionalized (Z)-2-(buta-1,3-dienyl)phenols and 2-methyl-2H-chromenes:: Use of amine, ruthenium and base-catalysis

A practical and simple one-pot multi-catalysis process for the synthesis of highly substituted benzo[b]oxepines 5, (Z)-2-(buta-1,3-dienyl)phenols 6 and 2-methyl-2H-chromenes 7 from simple starting materials was achieved for the first time through ring-closing metathesis/base-induced ring opening/[1,7]-sigmatropic hydrogen shift reactions. The synthesis of privileged (Z)-2-(buta-1,3-dienyl)phenols 6 via base-induced ring opening of highly functionalized benzo[b]oxepines 5 is described. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).