Gold-Catalyzed Synthesis of Benzil Derivatives and α-Keto Imides via Oxidation of Alkynes
摘要:
An efficient process based on the gold-catalyzed redox reaction has been developed to oxidize 1,2-diarylacetylene or ynamide to 1,2diaryldiketone or a-keto imide respectively. This process can tolerate a variety of functional groups and affords 1,2-dicarbonyl compounds in excellent yields under mild reaction conditions.
A novel method for metal‐free oxothiolation of ynamides to construct oxazolidine‐2,4‐diones bearing sulfur‐substituted quaternary carbonatoms has been developed. It represents a rare C−O bond cleavage of ynamides, as well as a facile and tandem approach for the formation of C−O, C−S, and C−Cl bonds. This redox‐neutral protocol can be applied to the synthesis of multisubstituted oxazolidine‐2,4‐diones
Metal-Free Iodine-Catalyzed Oxidation of Ynamides and Diaryl Acetylenes into 1,2-Diketo Compounds
作者:Seung Woo Kim、Tae-Woong Um、Seunghoon Shin
DOI:10.1021/acs.joc.8b00484
日期:2018.4.20
Metal-free oxidation of ynamides is described, employing pyridine-N-oxides as oxidants under molecular iodine catalysis. In stark contrast to Brønsted acid catalysis, iodophilic activation of ynamides diverts the reaction manifold into a dioxygenation pathway. This oxidation is very rapid at room temperature with only 2.5 mol % I2. Furthermore, this protocol could be extended to nonactivated alkynes
An efficient iodine-mediatedoxidation reaction for ynamides has been developed to produce N-monosubstituted α-ketoamides and α-ketoimides. This oxidative method, which exhibits good functional group tolerance, was performed under mild conditions without a metal catalyst.
microwave assistance. DFT calculations indicate that DMSO nucleophilicallyattacks the ethylic triple bond and transfers its oxygenatom to the triple bond to form zwitterionic anionic N-sulfonyliminiums to trigger the reaction. Then it nucleophilicallyattacks the generated iminium intermediates to accomplish the oxidation via the second oxygenatom transfer. The current method provides a straightforward