Base-promoted benzannulation of conjugated -sulfonylhydrazones and 3-formylchromones for the synthesis of diverse biaryl sulfones is described. The approach facilitates new C-C and C-S bond formation via the cascade diazo formation/Michael addition/ring opening/denitrogenative sulfonylation/intramolecular cycloaddition/dehydration and introduces diverse functional groups onto biaryl sulfones. The synthesized compounds are converted to aryl sulfones bearing bioactive benzisoxazole and benzofuran frameworks. Moreover, the synthesized biaryl sulfones possess potent turn-on fluorescence sensing and UV absorbance properties.
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http://dx.doi.org/10.1021/acs.orglett.0c02724 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, China.
This study addresses a challenge in organic synthetic chemistry: the direct cleavage of amide bonds, which is typically hampered by the thermodynamic stability of the C(Ar)-C(acyl) bond. Previous methods often rely on "CO" extrusion-jointing transition metal-catalyzed process and require activated tertiary amides, limiting their applicability due to incompatibility with reactive functional groups such as halogens. Herein, we report a transition metal-free approach for the deamidative cyclization of biaryl diamides via a radical process, yielding dibenzolactam derivatives.
View Article and Find Full Text PDFJ Am Chem Soc
August 2024
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
This work describes highly enantioselective nitrene transfer to hydrocinnamyl alcohols (benzylic C-H amination) and allylic alcohols (aziridination) using ion-paired Rh (II,II) complexes based on anionic variants of Du Bois' esp ligand that are associated with cinchona alkaloid-derived chiral cations. Directed by a substrate hydroxyl group, our previous work with these complexes had not been able to achieve high enantioselectivity on these most useful short-chain compounds, and we overcame this challenge through a combination of catalyst design and modified conditions. A hypothesis that modulation of the linker between the anionic sulfonate group and the central arene spacer might provide a better fit for shorter chain length substrates led to the development of a new biaryl-containing scaffold, which has allowed a broad scope for both substrate classes to be realized for the first time.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2024
Aix Marseille Université, CNRS, Centrale Méditerranée, iSm2, 13397, Marseille, France.
Atropisomers hold significant fascination, not only for their prevalence in natural compounds but also for their biological importance and wide-ranging applications as chiral materials, ligands, and organocatalysts. While biaryl and heterobiaryl atropisomers are commonly studied, the enantioselective synthesis of less abundant heteroatom-linked non-biaryl atropisomers presents a formidable challenge in modern organic synthesis. Unlike classical atropisomers, these molecules allow rotation around two bonds, resulting in low barriers to enantiomerization through concerted bond rotations.
View Article and Find Full Text PDFOrg Lett
April 2024
Department of Chemistry, University of Manchester, Oxford Rd, Manchester, M13 9PL, U.K.
We describe a transition metal-free approach to hindered 3-amino-2-aryl phenols through a cascade nucleophilic addition / Smiles-Truce rearrangement of a functionalized Kobayashi aryne precursor. Under anionic conditions, secondary alkyl amines add to the aryne intermediate to set up an aryl transfer from a neighboring sulfonate group. The use of a sulfonate, rather than the more typical sulfonamide, enables access to phenolic biaryl products that are important motifs in natural products and pharmaceuticals.
View Article and Find Full Text PDFOrg Lett
October 2023
Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India.
Herein, atroposelective synthesis of axially chiral biaryls with unactivated olefins by a palladium-catalyzed C-H olefination using a chiral transient directing group strategy has been disclosed. This protocol is well compatible with a variety of biaryl-2-aldehydes as well as various olefins such as allyl sulfonamides and allyl sulfones to provide the atroposelective olefinated products in synthetically useful yields with excellent enantioselectivities up to >99% ee. In addition, a wide number of axially chiral biaryl alcohols were synthesized by the simple diversification of the products in excellent enantioselectivity.
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