Catalyzed organic reactions that produce an organoboron compound
Metal-catalyzed C–H borylation reactions are transition metal catalyzed organic reactions that produce an organoboron compound through functionalization of aliphatic and aromatic C–H bonds and are therefore useful reactions for carbon–hydrogen bond activation.[1] Metal-catalyzed C–H borylation reactions utilize transition metals to directly convert a C–H bond into a C–B bond. This route can be advantageous compared to traditional borylation reactions by making use of cheap and abundant hydrocarbon starting material, limiting prefunctionalized organic compounds, reducing toxic byproducts, and streamlining the synthesis of biologically important molecules.[2][3] Boronic acids, and boronic esters are common boryl groups incorporated into organic molecules through borylation reactions.[4] Boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent and two hydroxyl groups. Similarly, boronic esters possess one alkyl substituent and two ester groups. Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general formula (RO)2B-B(OR)2. For example, bis(pinacolato)diboron (B2Pin2), and bis(catecholato)diborane (B2Cat2) are common boron sources of this general formula.[5]
B2pin2 and B2cat2
The boron atom of a boronic ester or acid is sp2 hybridized possessing a vacant p orbital, enabling these groups to act as Lewis acids. The C–B bond of boronic acids and esters are slightly longer than typical C–C single bonds with a range of 1.55-1.59 Å. The lengthened C–B bond relative to the C–C bond results in a bond energy that is also slightly less than that of C–C bonds (323 kJ/mol for C–B vs 358 kJ/mol for C–C).[6] The carbon–hydrogen bond has a bond length of about 1.09 Å, and a bond energy of about 413 kJ/mol. The C–B bond is therefore a useful intermediate as a bond that replaces a typically unreactive C–H bond.
Organoboron compounds are organic compounds containing a carbon-boron bond. Organoboron compounds have broad applications for chemical synthesis because the C–B bond can easily be converted into a C–X (X = Br, Cl), C–O, C–N, or C–C bond. Because of the versatility of the C–B bond numerous processes have been developed to incorporate them into organic compounds.[7] Organoboron compounds are traditionally synthesized from Grignard reagents through hydroboration, or diboration reactions.[8] Borylation provides an alternative.
^Hartwig, John F. (2012). "Borylation and Silylation of C–H Bonds: A Platform for Diverse C–H Bond Functionalizations". Accounts of Chemical Research. 45 (6): 864–873. doi:10.1021/ar200206a. ISSN 0001-4842. PMID 22075137.
^Cho, J. Y.; Tse, M. K.; Holmes, D.; Maleczka, R. E. Jr.; Smith, M. R. (2001). "Remarkably Selective Iridium Catalysts for the Elaboration of Aromatic C-H Bonds". Science. 295 (5553): 305–8. doi:10.1126/science.1067074. PMID 11719693. S2CID 21096755.
^Ishiyama, T.; Nobuta, Y.; Hartwig, J. F.; Miyaura, N. Chem. Commun.2003, 2924.
^Brown, H. C.; Kramer, G. W.; Levy, A. B.; Midland, M. M. Organic Synthesis via Boranes; Wiley-Interscience: New York, 1975; Vol. 1.
^Braunschweig, H.; Guethlein, F. (2011). "Transition-Metal-Catalyzed Synthesis of Diboranes(4)". Angewandte Chemie International Edition. 50 (52): 12613–12616. doi:10.1002/anie.201104854. PMID 22057739.
^Hall, D. G. (2011) Structure, Properties, and Preparation of Boronic Acid Derivatives, in Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials (Volume 1 and 2), Second Edition (ed D. G. Hall), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi:10.1002/9783527639328.ch1
^Mkhalid, Ibraheem A. I.; Barnard, Jonathan H.; Marder, Todd B.; Murphy, Jaclyn M.; Hartwig, John F. (2010). "C–H Activation for the Construction of C–B Bonds". Chemical Reviews. 110 (2): 890–931. doi:10.1021/cr900206p. PMID 20028025.
Metal-catalyzed C–H borylation reactions are transition metal catalyzed organic reactions that produce an organoboron compound through functionalization...
Miyaura borylation, also known as the Miyaura borylation reaction, is a named reaction in organic chemistry that allows for the generation of boronates...
and competes with hydrogen activation. Amine-borane FLPs catalyse the borylation of electron-rich aromatic heterocycles (Scheme 1). The reaction is driven...
triflates with diboronyl esters in a coupling reaction known as the Miyaura borylation reaction. An alternative to esters in this method is the use of diboronic...
have also been implicated as intermediates in electrophilic aromatic borylation reactions. In many examples of this reaction, a catalyst is used to activate...
reagents. One common cyclic organoboron reagent is 9-BBN. Metal-catalyzed borylation reactions produce an organoboron compound from aliphatic or aromatic C-H...
of benzoyl peroxide (2 mol %) as an initiator:. Alternatively similar borylation can be achieved using transition metal carbonyl complexes including dimanganese...
of aldehydes, ketones, and carboxylic acids. Pinacolborane is used in borylation, a form of C-H activation. Dehydrogenation of pinacolborane affords dipinacolatodiborane...
cyclic and acyclic enones. The Miyaura-Ishiyama borylation reaction is also known as the Miyaura borylation reaction. In this reaction, a catalytic system...
synthesis of hindered tertiary boronic esters under in situ lithiation–borylation conditions". Chemical Communications. 52 (30): 5289–5292. doi:10.1039/C6CC00536E...
; Hartwig, John F. (2023). "Transition-Metal-Catalyzed Silylation and Borylation of C–H Bonds for the Synthesis and Functionalization of Complex Molecules"...
ring, and both have been synthesised involving ligand-controlled C–H borylation. Borthwick AD (2012). "2,5-Diketopiperazines: Synthesis, Reactions, Medicinal...
Stereocontrolled Synthesis of the 2-ene-1,4-diol Core through a Lithiation–Borylation–Allylation Sequence". Angewandte Chemie International Edition. 49 (37):...
synthesis. This reaction is sometimes telescoped with the related Miyaura borylation; the combination is the Suzuki–Miyaura reaction. It is widely used to...
doi:10.1021/ja00377a032. Hartwig, John F. (2011). "Regioselectivity of the Borylation of Alkanes and Arenes". Chemical Society Reviews. 40 (4): 1992–2002. doi:10...
heterobimetallic bond-breaking process is also employed in the IPrCuFp-catalyzed C-H borylation system developed by Mankad (Scheme 5). Bimetallic cleavage of the B-H...
conversion of an aryl halide to a phenol (the first step is a Miyaura borylation). Sodium perborate monohydrate is quickly hydrolyzed into hydrogen peroxide...
- are required to stabilize Rh(V). This oxidation state is invoked in borylation reactions. Cyclometalated rhodium compounds constitute an important class...
Irvine. Blum works on mechanistic chemistry, most recently focusing on borylation reactions and the development of single-molecule and single-particle fluorescence...
wide array of reactions, including the arylation of ketones and esters, borylation of aryl chlorides, and the arylation of indoles. Many modified versions...
installation of adjacent tertiary benzylic stereocentres using lithiation–borylation–protodeboronation methodology. Application to the synthesis of bifluranol...
related pinacolborane, are intermediates in transition metal-catalyzed borylation reactions. Oxidative addition is the main route to metal boryl complexes...
Matzger, A. J.; Sanford, M. S. "Catalyst-Controlled Selectivity in the C–H Borylation of Methane and Ethane," Science 2016, 351, 1421–1424. Camasso, N. M.;...
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