title: Catalytic formal [4 + 2] cycloadditions between unactivated allenes and N-hydroxyaniline catalyzed by AuCl₃/CuCl₂/O₂.
abstract: AuCl3-catalyzed formal [4 + 2]-cycloadditions between substituted allenes and N-hydroxyanilines are described. This reaction sequence comprises initial isomerizations of allenes to butadienes under N2 and subsequent oxidations of N-hydroxyanilines to nitrosoarenes under O2. CuCl2 (5 mol %) was added in the second step to increase the oxidation efficiency. The reactions are compatible with various 1,1-di- and 1,1,3-trisubstituted allenes and N-hydroxyaniline derivatives. Our experimental data reveal that the roles of AuCl3 are 3-fold, including catalytic oxidations of N-hydroxyaniline derivatives to nitrosoarenes, isomerizations of alkyl-substituted allenes to dienes, and final nitroso/butadiene [4 + 2] cycloadditions.
authors.affiliation: Department of Chemistry, National Tsing Hua University , Hsinchu, Taiwan, ROC.
authors.forename: Jian-Ming
authors.initials: JM
authors.lastname: Chen
authors.forename: Chin-Jung
authors.initials: CJ
authors.lastname: Chang
authors.forename: Yao-Jin
authors.initials: YJ
authors.lastname: Ke
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu