An enantioselective Cu(I)-catalyzed coupling of N-carboxyindoles with various 2-naphthols and phenols for the synthesis of axially chiral arylindoles has been developed. Our mechanistic studies, bolstered by experimental evidence and DFT calculations, reveal a novel closed-shell mechanism involving outer-sphere attack of N-carboxyindoles on the Cu-bound naphthols. This mechanism allows for unprecedented diversity of 2-naphthols and phenols in C-H arylation. Enantiocontrol is achieved through center-to-axis chirality transfer via a key dearomatized naphthol intermediate, which prevents undesired epimerization of the C-C axis.
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http://dx.doi.org/10.1021/acs.orglett.4c02482 | DOI Listing |
Org Lett
August 2024
Department of Chemistry, Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Korea.
An enantioselective Cu(I)-catalyzed coupling of N-carboxyindoles with various 2-naphthols and phenols for the synthesis of axially chiral arylindoles has been developed. Our mechanistic studies, bolstered by experimental evidence and DFT calculations, reveal a novel closed-shell mechanism involving outer-sphere attack of N-carboxyindoles on the Cu-bound naphthols. This mechanism allows for unprecedented diversity of 2-naphthols and phenols in C-H arylation.
View Article and Find Full Text PDFMolecules
July 2024
Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA.
A one-pot [3+3] aldol-SAr-dehydration annulation sequence was utilized to fuse hindered phenols onto aromatic substrates. The transformation joins doubly activated 1,3-disubstituted acetone derivatives (dinucleophiles) with C5-activated 2-fluorobenzaldehyde SAr acceptors (dielectrophiles) in the presence of KCO in DMF at 65-70 °C to form polysubstituted 2-naphthols and 7-hydroxyquinolines. The reaction is regioselective in adding the most stable anionic center to the aldehyde followed by SAr closure of the less stabilized anion to the electron-deficient aromatic ring.
View Article and Find Full Text PDFChemistry
April 2024
Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097, Warsaw, Poland.
The electrochemical oxidative dearomatizing methoxylation of phenols and naphthols was developed. It provides an alternative route for the preparation of methoxycyclohexadienones, important and versatile synthetic intermediates, that eliminates the need for stoichiometric high-energy chemical oxidants and generates hydrogen as a sole by-product. The reaction proceeds in a simple constant current mode, in an undivided cell, and it employs standardized instrumentation.
View Article and Find Full Text PDFJ Org Chem
November 2023
Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700 009, West Bengal, India.
Benzofuran and naphthofuran derivatives are synthesized from readily available phenols and naphthols. Regioselective ring openings of 2-azirine followed by in situ aromatization using a catalytic amount of Brønsted acid have established the novelty of the methodology. The involvement of a series of 2-azirines with a variety of phenols, 1-naphthols, and 2-naphthols showed the generality of the protocol.
View Article and Find Full Text PDFChem Pharm Bull (Tokyo)
September 2023
Graduate School of Pharmaceutical Sciences, Kyoto University.
In this article, an electron donor-acceptor (EDA) complex between a triarylamine and B(CF) that catalyzes the dehydrogenative cross-coupling of phenols is described. We demonstrate, for the first time, that the use of both components of the radical ion pairs generated by the photoexcitation of the EDA complex as co-catalysts, and the triarylaminium radical cation (NAr) successfully promotes dehydrogenative cross-coupling between electron-rich phenols and 2-naphthols to provide electron-rich biphenol motifs using molecular oxygen as a terminal oxidant.
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