A palladium-catalyzed synthesis of tetrasubstituted allenes from aryl bromides and aryl diazoacetates is developed. This transformation proceeded an aryl to alkenyl 1,4-palladium migration/carbene insertion/β-H elimination sequence under mild reaction conditions.
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http://dx.doi.org/10.1039/d2ob00751g | DOI Listing |
J Am Chem Soc
December 2024
State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China.
Catalytic asymmetric transformation of donor-acceptor cyclopropanes (DACs) has been proven to be a highly valuable and robust strategy to construct diverse types of enantioenriched molecules. However, the use of 1,1,2,2-tetrasubstituted DACs to form products bearing quaternary stereocenters remains a long-term unsolved challenge. Here, we report the copper-catalyzed asymmetric aminative ring opening of tetrasubstituted alkynyl DACs that delivers a myriad of α-tertiary amines with high levels of enantioselectivities.
View Article and Find Full Text PDFOrg Chem Front
December 2024
Department of Chemistry, University of Basel St Johanns-Ring 19 Basel 4056 Switzerland https://www.chemie1.unibas.ch/Bmayor/.
This work explores the use of a cross-shaped organic framework that is used as a template for the investigation of multi-functionalized chromophores. We report the design and synthesis of a universal cross-shaped building block bearing two bromines and two iodines on its peripheral positions. The template can be synthesized on a gram scale in a five-step reaction comprising an oxidative homo-coupling macro-cyclization.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, 30 Puzhu Rd S., Nanjing 211816, China.
An electrochemical reductive bimolecular cycloaddition of 2-arylideneindane-1,3-diones has been reported for the synthesis of spirocyclopentanole indane-1,3-diones bearing five contiguous stereocenters with vicinal tetrasubstituted stereocenters, especially involving a quaternary carbon center, in moderate to good yields and excellent diastereoselectivities. The present protocol features mild reaction conditions, no external chemical redox reagents, excellent atom economy, and gram-scale synthesis. In addition, a mechanistic investigation indicates that the reactions proceed through a radical pathway.
View Article and Find Full Text PDFOrg Lett
December 2024
Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, People's Republic of China.
An efficient dehydrative coupling of propargylic alcohols with diarylphosphine oxides to construct tetrasubstituted allenylphosphoryl compounds in the presence of a Pd/Brønsted acid co-catalyst has been developed. As a benefit from the use of a Brønsted acid, this reaction could perform under mild conditions with excellent yields, accommodating a wide range of functional groups. The potential utility of this method has also been demonstrated.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan.
Herein, we present the enantioselective synthesis of 2,3-dihydro-4-quinolones bearing chiral tetrasubstituted carbons from isatins and 2'-aminoacetophenones. The transformation is mediated by a chiral phosphoric acid catalyst and proceeds via an generated ketimine and subsequent enantioselective intramolecular cyclization. The methodology features a broad scope and functional group tolerance with yields and enantioselectivities of up to 99% and 98% ee.
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