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. and the final nitroso/butadiene [4 + 2] cycloadditions under O2. CuCl2 (5 mol %) was added in the second step to increase the oxidation efficiency, which obviously improved the yields of overall reactions .