Difluorocarbene has important applications in pharmaceuticals, agrochemicals and materials, but all these applications proceed using just a few types of reaction by taking advantage of its intrinsic electrophilicity. Here, we report a palladium-catalysed strategy that confers the formed palladium difluorocarbene (Pd=CF) species with both nucleophilicity and electrophilicity by switching the valence state of the palladium centre (Pd(0) and Pd(II), respectively). Controllable catalytic difluorocarbene transfer occurs between readily available arylboronic acids and the difluorocarbene precursor diethyl bromodifluoromethylphosphonate (BrCFPO(OEt)). From just this simple fluorine source, difluorocarbene transfer enables access to four types of product: difluoromethylated and tetrafluoroethylated arenes and their corresponding fluoroalkylated ketones. The transfer can also be applied to the modification of pharmaceuticals and agrochemicals as well as the one-pot diversified synthesis of fluorinated compounds. Mechanistic and computational studies consistently reveal that competition between nucleophilic and electrophilic palladium difluorocarbene ([Pd]=CF) is the key factor controlling the catalytic difluorocarbene transfer.
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http://dx.doi.org/10.1038/s41557-019-0331-9 | DOI Listing |
Nat Commun
October 2024
Shenzhen University of Advanced Technology, Shenzhen, 518055, P. R. China.
We disclose herein an unprecedented Pd-catalyzed difluorocarbene transfer reaction, which assembles a series of structurally interesting chiral spiro ketones with generally over 90% ee. Commercially available BrCFCOK serves as the difluorocarbene precursor, which is harnessed as a user-friendly and safe carbonyl source in this transformation. Preliminary mechanistic studies exclude the formation of free CO in the reaction process, and importantly, we also find that BrCFCOK outcompete gaseous CO and several common CO surrogates in this asymmetric process.
View Article and Find Full Text PDFOrg Lett
September 2024
Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, People's Republic of China.
An approach for the ligand-free Pd-catalyzed C-H activation/[5 + 1] cyclization carbonylation by employing readily available ClCFCOONa as a carbonyl source via difluorocarbene transfer and hydrolysis has been developed. The current protocol enables us to obtain a series of carbonylation cyclization product benzopyranone and phenanthridinone derivatives in up to 91% yield with excellent functional group compatibility. This protocol has the advantages of mild reaction conditions, wide applicable substrates, and simple and safe operation and provides a new method for the synthesis of complex lactam and lactone compounds.
View Article and Find Full Text PDFJ Am Chem Soc
January 2024
Institute of Next Generation Matter Transformation, College of Material Sciences Engineering, Huaqiao University, Xiamen, Fujian 361021, China.
Herein, we report a ligand-controlled palladium-catalyzed method that enables the synthesis of ynones and γ-butenolides with excellent regioselectivity from the same set of readily available aryl iodides, aryl acetylenes, and BrCFCOK. In this reaction, the [Pd]═CF does demonstrate electrophilicity and can generate CO readily when reacting with HO. It is environmentally friendly and safe compared to traditional methods, and the current protocol enables us to afford ynones and γ-butenolides in high yields with excellent functionality tolerance.
View Article and Find Full Text PDFChem Commun (Camb)
December 2023
Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
A novel Pd-catalyzed assembly of -substituted phthalimides by merging of [4+1] cycloaddition and difluorocarbene transfer carbonylation from 2-iodo--phenylbenzamides and difluorocarbene precursors is disclosed. Difluorocarbene acts as a carbonyl source and simultaneously forms one C-C bond, one C-N bond and one CO bond to produce -substituted phthalimides in high yields.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2023
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China.
A palladium-catalyzed reductive difluorocarbene transfer reaction that tames difluorocarbene to couple with two electrophiles has been developed, representing a new mode of difluorocarbene transfer reaction. The approach uses low-cost and bulk industrial chemical chlorodifluoromethane (ClCF H) as the difluorocarbene precursor. It produces a variety of difluoromethylated (hetero)arenes from widely available aryl halides/triflates and proton sources, featuring high functional group tolerance and synthetic convenience without preparing organometallic reagents.
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