Quaternary carbon centers are desirable targets for drug discovery and complex molecule synthesis, yet the synthesis of these motifs within traditional cross-coupling paradigms remains a significant challenge due to competing β-hydride elimination pathways. In contrast, the bimolecular homolytic substitution (S2) mechanism offers a unique and attractive alternative pathway. Metal porphyrin complexes have emerged as privileged catalysts owing to their ability to selectively form primary metal-alkyl complexes, thereby eliminating the challenges associated with tertiary alkyl complexation with a metal center. Herein, we report an iron-catalyzed cross-electrophile coupling of tertiary bromides and primary alkyl electrophiles for the formation of all-carbon quaternary centers through a biomimetic S2 mechanism.
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http://dx.doi.org/10.1021/jacs.4c14942 | DOI Listing |
J Am Chem Soc
December 2024
Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States.
Quaternary carbon centers are desirable targets for drug discovery and complex molecule synthesis, yet the synthesis of these motifs within traditional cross-coupling paradigms remains a significant challenge due to competing β-hydride elimination pathways. In contrast, the bimolecular homolytic substitution (S2) mechanism offers a unique and attractive alternative pathway. Metal porphyrin complexes have emerged as privileged catalysts owing to their ability to selectively form primary metal-alkyl complexes, thereby eliminating the challenges associated with tertiary alkyl complexation with a metal center.
View Article and Find Full Text PDFJ Am Chem Soc
February 2024
Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, 837 Bloom Walk, Los Angeles, California 90089-1661, United States.
Cross-electrophile couplings are influential reactions that typically require a terminal reductant or photoredox conditions. We discovered an iron-catalyzed reaction that couples benzyl halides with disulfides to yield thioether products in the absence of a terminal reductant and under photoredox conditions. The disclosed platform proceeds without sulfur-induced catalyst poisoning or the use of an exogenous base, supporting a broad scope and circumventing undesired elimination pathways.
View Article and Find Full Text PDFSTAR Protoc
March 2024
Department of Science and Technology, North Sichuan Medical College, Nanchong, Sichuan 637100, P.R. China; Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, P.R. China. Electronic address:
Organochlorides are a crucial class of electrophiles in organic synthesis. Here, we present a protocol for the cross-electrophile coupling of aryl chlorides with unactivated alkyl chlorides, facilitated by an iron/Bpin catalytic system. We describe steps for the coupling of aryl chlorides with alkyl chlorides, followed by purification of products.
View Article and Find Full Text PDFOrg Lett
May 2022
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China.
In this protocol, we demonstrate our discovery that iron is able to efficiently catalyze the reductive allylic defluorinative ketyl olefin coupling reaction between α-trifluoromethyl alkenes and unactivated ketones. This operationally simple cross-electrophile reaction circumvents the use of pre-generated organometallics and allows for the synthesis of diverse functional-group-rich tertiary -difluorohomoallylic alcohols through a polarity-reversed strategy. Preliminary mechanistic studies support a mechanism that proceeds through a ketyl formation/olefin insertion/β-fluoro elimination sequence.
View Article and Find Full Text PDFOrg Lett
March 2020
School of Materials Science and Engineering, Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, Shanghai University, Shanghai, China.
We present herein a rare and efficient method for the creation of vinylated all carbon quaternary centers via Fe-catalyzed cross-electrophile coupling of vinyl halides with tertiary alkyl methyl oxalates. The reaction displays excellent functional group tolerance and broad substrate scope, which allows cascade radical cyclization and vinylation to afford complex bicyclic and spiral structural motifs. The reaction proceeds via tertiary alkyl radicals, and the putative vinyl-Br/Fe complexation appears to be crucial for activating the alkene and enabling a possibly concerted radical addition/C-Fe forming process.
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