The dehydrogenative β'-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β'-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.
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Org Lett
January 2025
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China.
Herein, we report an approach for the synthesis of 2-sulfonyl carbazoles from the oxidative C-H sulfonylation of tetrahydrocarbazoles. The mechanistic study reveals that this special selectivity is realized by the addition of a sulfonyl radical to the 3,4-dihydrocabazole intermediate via dehydrogenative desaturation of tetrahydrocarbazoles. This approach features readily available starting materials, high regioselectivity, broad substrate scope, and attractive synthetic utility.
View Article and Find Full Text PDFJ Org Chem
January 2025
Department of Pharmacy, College of Pharmacy, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea.
In this study, we developed palladium-catalyzed dehydrogenative cyclization to transform 1-(2-aminoaryl)-3-arylpropan-1-ones into 2-arylquinolin-4(1)-ones, also known as aza-flavones which are the bioisosteres of flavones, in an atom-economic manner. This method exhibited excellent chemical compatibility with a broad substrate scope, accommodating up to 25 derivatives. Additionally, kinetic studies were performed to elucidate the reaction mechanism.
View Article and Find Full Text PDFNat Commun
January 2025
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
The advancement of an effective hydrogen liberation technology from liquid organic hydrogen carriers, particularly cycloalkanes such as cyclohexane and methylcyclohexane, holds significance in realizing a hydrogen-centric society. However, the attainment of homogeneous catalytic acceptorless dehydrogenation characterized by elevated selectivity for thorough aromatization under mild conditions remains unrealized. In this study, a catalyst system, facilitated by a double hydrogen atom transfer processes, has been devised for the catalytic acceptorless dehydrogenation of inert cycloalkanes at ambient temperature under visible light irradiation.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
University of Oxford, Department of Chemistry Chemistry Research Laboratory, Mansfield Road, OX1 3TA, Oxford, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
Compounds containing quaternary stereocentres are a valuable motif in biologically active compounds. Herein we present our strategy to utilise the hydrogen borrowing manifold to access α-quaternary ketones via a tandem acceptorless dehydrogenation-cyclisation cascade. This new application of the methodology results in the formation of five- and six-membered carbocycles with a high degree of diastereoselectivity.
View Article and Find Full Text PDFOrg Lett
January 2025
China Guangxi Key Laboratory of Pharmaceutical Precision Detection and Screening, Guangxi Key Laboratory of Bioactive Molecules Research and Evaluation, and Key Laboratory of Micro-Nanoscale Bioanalysis and Drug Screening of Guangxi Education Department, Pharmaceutical College, Guangxi Medical University, Nanning 530021, China.
Herein, a one-pot domino catalyzed three-component process is described, which is initiated by a palladium/zinc cooperatively catalyzed cycloaddition between trimethylenemethane (TMM) and unactivated alkyl/aryl imines, followed by one-pot isomerization and Zn(OTf)-catalyzed DDQ oxidation, furnishing valuable substituted pyrroles. We disclose that the palladium/zinc cooperative catalysis affords a dual-Zn(OTf)-stabilized azapalladacycle, wherein the Pd-N bond is polarized by Zn(OTf), facilitating a unique outer-sphere allylic amination. Moreover, subsequent DDQ dehydrogenation can be feasibly promoted by zinc catalysis.
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