catalytic methods for the oxidative furan-recyclizations remain scarcely investigated. Given this, we report a means of manganese-catalyzed oxidations of furan with low loading, achieving the Achmatowiczrearrangement in the presence of hydrogen peroxide as an environmentally benign oxidant under mild conditions with wide functional group compatibility.
Di- and triheteroarylalkanes via self-condensation and intramolecular Friedel–Crafts type reaction of heteroaryl alcohols
作者:Seema Dhiman、S. S. V. Ramasastry
DOI:10.1039/c3ob41945b
日期:——
diheteroarylmethanes and 1,3-diheteroarylpropenes has been developed via Yb(III)-catalyzed sequential self-condensation of 2-furfuryl (or 2-thienyl or 3-indolyl) alcohols followed by intramolecular Friedel–Craftstypereaction and elimination of an aldehyde. This method offers a powerful entry and a potential alternative to the traditional synthesis of diheteroarylalkanes, which are precursors to the synthesis
leaving group, azide is capable of initiating the generation of a furfuryl cation under the Lewis acid-catalyzed conditions, followed by reacting with the other azide to realize an intermolecular [3 + 2] cycloaddition/furan ring-opening cascade. By extending the reaction time, a fragmentationreaction of resulting furfuryl triazoles occurs to afford 1H-triazoles in high yield. Control studies demonstrated
Gold Catalysis: Efficient 1,3-Induction with Diastereotopic Homopropargyl Alcohols in the Phenol Synthesis
作者:A. Stephen K. Hashmi、Melissa Hamzić、Matthias Rudolph、Martin Ackermann、Frank Rominger
DOI:10.1002/adsc.200900402
日期:2009.10
Furans with diastereotopic alkynyl groups were prepared and then converted to anellated phenols in gold-catalyzed reactions. In all cases a highly diastereoselective reaction was observed. The stereochemical outcome of the 1,3-induction could be assigned by two independent crystal structure analyses, showing a cis-arrangement of the two alkyl substituents on the benzoanellated cyclohexene ring.
Gold Catalysis: Non-Spirocyclic Intermediates in the Conversion of Furanynes by the Formal Insertion of an Alkyne into an Aryl-Alkyl CC Single Bond
作者:A. Stephen K. Hashmi、Tobias Häffner、Weibo Yang、Sreekumar Pankajakshan、Sascha Schäfer、Lara Schultes、Frank Rominger、Wolfgang Frey
DOI:10.1002/chem.201200306
日期:2012.8.20
It takes al‐kynes: The formation of furyl‐substituted heterocycles from furanynes with donor groups on the furan–alkyne tether and mechanistic control experiments indicate the involvement of open‐chained carbenium ions in the overall insertion of an alkyne into a CCbond, rather than the usual spirocyclic intermediates (see scheme).