Insertion chemistry of isocyanide molecules was used to functionalize C-F sp(2) bonds after their oxidative addition across the metal center in a β-diketiminate niobium(iii) imido complex (BDI)Nb(N(t)Bu)(C6H6). The complexes formed, 3a-b ([BDI]Nb(PhC[double bond, length as m-dash]N)(N(t)Bu)(F) (R = 1,6-diisopropylphenyl, tert-butyl), were characterized by NMR spectroscopy and X-ray analysis. Further treatment with phenylsilane induced H/F exchange under mild conditions, which was followed by hydride transfer to the inserted isocyanide. Divergent reactivity was observed when the two analogous aryl and tert-butyl isocyanide insertion products were treated with phenylsilane.
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http://dx.doi.org/10.1039/c5dt02082d | DOI Listing |
Org Lett
August 2024
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, 201620, China.
We present a palladium-catalyzed ring-opening reaction that induces indoles to cross-couple with -difluorocyclopropanes. The reaction proceeds through a domino process of C-C bond activation and C-F bond elimination, followed by C-C(sp2) coupling to produce various 2-fluoroallylindoles. This method is characterized by its high functional group tolerance, good yields and high regioselectivity, under base-free conditions.
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December 2022
Chemistry Department, Georgetown University, Washington, DC 20057, United States.
Cross-coupling of alkyl fluorides and organocuprates is accomplished via aluminum halide mediated C-F bond activation and subsequent C-C and C-C bond formation. Relatively mild conditions allow for smooth activation of notoriously challenging primary and secondary alkyl fluorides while competing alkyl chain rearrangement, HF elimination, and homocoupling reactions are effectively controlled. The utility and functional group tolerance are demonstrated with 23 examples and a variety of coupling products obtained in up to 88% yield.
View Article and Find Full Text PDFChem Rev
December 2022
College of Advanced Interdisciplinary Science and Technology, Henan University of Technology, Zhengzhou 450001, China.
Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp)-H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp C-H and C-F bonds until June 2022.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2022
Department of Chemistry, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA.
The fundamental challenge of C-F bond formation by reductive elimination has been met by compounds of select transition metals and fewer main group elements. The work detailed herein expands the list of main group elements known to be capable of reductively eliminating a C-F bond to include tellurium. Surprising and novel modes of both sp and sp C-F bond formation were observed alongside formation of Te cations during two separate attempts to synthesize/characterize fluorinated organotellurium(VI) cations in superacidic media (SbF /SO ClF).
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July 2022
Department of Nanopharmaceutical Sciences, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan.
Potassium-base-mediated defluoroetherification of aryl and heteroaryl fluorides with alkoxyboronic acid pinacol esters under transition-metal-free conditions is reported. This protocol efficiently and safely provides a wide variety of aryl ethers in high yields without using metal catalysts, specific ligands, and harsh conditions to selectively forge C-O bonds via the C-F cleavage. This method can be applied to the late-stage etherification of structurally complex C-fluorides and bioactive alcohols, such as β-estradiol, calciferol, and tocopherol.
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