Gold-catalyzed synthesis of nonsymmetrical heteroaryl-substituted triarylmethanes using 2-(1-alkynyl)-2-alken-1-ones and vinyldiazo ketones is described. In this catalytic sequence, vinyldiazo ketones attack gold-containing 3-furylbenzyl cations to form the observed C(1)-addition products. We also note that vinyldiazo ketones can be thermally cyclized to yield pyrazole derivatives, which can react with 3-furylbenzyl cations to afford pyrazole-containing triarylmethanes, corresponding to a N(5)-addition path.
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http://dx.doi.org/10.1021/acs.orglett.0c02765 | DOI Listing |
Org Lett
December 2023
Institute of Green Chemistry and Molecular Engineering, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.
A visible light-promoted radical (3+3) annulation of vinyldiazo compounds and bromodifluoromethyl alkynyl ketones for the construction of -difluoro-masked -quinone methides (-QMs) is described. The reactivity of this new type of -QM precursor is demonstrated by its (4+1) cycloaddition with sulfur ylides, affording monofluorinated aromatic benzofurans by the elimination of HBr without external oxidants.
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February 2021
Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan 30013, Republic of China.
This work describes gold-catalyzed additions of vinyldiazo ketones to -(-alkynylphenyl)imines to yield 3-(furan-2-ylmethyl)-1-indoles involving skeletal rearrangement; these new catalytic reactions are applicable to a wide range of substrates. We postulate a new mechanism involving an initial addition of diazo ketones to azomethine ylide intermediates to yield gold-containing -alkylated indole intermediates that undergo proton-induced 1,3-group migrations, generating azallyl gold and allylic cation pairs.
View Article and Find Full Text PDFOrg Lett
November 2020
Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC.
Gold-catalyzed synthesis of nonsymmetrical heteroaryl-substituted triarylmethanes using 2-(1-alkynyl)-2-alken-1-ones and vinyldiazo ketones is described. In this catalytic sequence, vinyldiazo ketones attack gold-containing 3-furylbenzyl cations to form the observed C(1)-addition products. We also note that vinyldiazo ketones can be thermally cyclized to yield pyrazole derivatives, which can react with 3-furylbenzyl cations to afford pyrazole-containing triarylmethanes, corresponding to a N(5)-addition path.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
August 2019
Frontier Research Center for Fundamental and Applied Science of Matters, Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
This work reports gold-catalyzed bicyclic annulations of 2-alkynyl-1-carbonylbenzenes with vinyldiazo ketones that serve as five-atom building units. The importance of these reactions is to access 4,5-dihydro-benzo[g]indazoles, which form the structural cores of various bioactive molecules. According to our mechanistic analysis, we postulate initial [5+4]-cycloadditions between benzopyrilium intermediates and vinyldiazo ketones, followed by 6-π-electrocyclizations to achieve the excellent stereoselectivity.
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