High-Order Use of Reactive Intermediates Stabilized by Oxygen Atom

点击翻译按钮获取中文摘要

In this project, we studied on high-order use of i) the reactive intermediates in Beckmann fragmentation reaction and ii) the dioxenium cations formed by acid treatment of orthoesters.i) The Beckmann fragmentation is one of the long-known reactions and used widely in organic synthesis. Although the reactive intermediates in the Beckmann fragmentation of the corresponding alpha-alkoxycycloalkanone oxime derivatives are very active electrophiles, only a limited kind of nucleophiles such as H2O,ROH,halide anion and carbon ones have been used so far. As the organic synthesis utilizing the intermediates of Beckmann fragmentation, we developed new carbon-carbon bond forming reactions using silicon-containing carbon nucleophiles and organoaluminium reagents. As an extention of the reactions, we also succeeded in developing a novel asymmetric carbon-carbon bond formation by combination of Beckmann fragmentation reaction and asymmetric synthesis using a chiral acetal and a highly stereoselective carbon-carbon bond formation in the reaction of 2,3-isopropyridenedioxycyclohexanone oxime esters with organpaluminium reagents.ii) Orthoesters work as superior electrophiles by forming dioxenium cations We succeeded in a facile one-pot formation of oxacyclic compounds in the reaction of triols with trialkyl orthoesters in the presence of acid catalyst. The reaction was successfully applied to the unprotected high-order alcohols giving polysubstituted tetrahydrofurans in a one-pot synthesis.