Heterobimetallic catalysis

Last updated

Heterobimetallic catalysis is an approach to catalysis that employs two different metals to promote a chemical reaction. Included in this definition are cases (Scheme 1) where: 1) each metal activates a different substrate (synergistic catalysis, used interchangeably with the terms "cooperative" and "dual" catalysis. [1] ), 2) both metals interact with the same substrate, and 3) only one metal directly interacts with the substrate(s), while the second metal interacts with the first. [2]

Contents

Scheme 1: Types of heterobimetallic catalysis Types2.gif
Scheme 1: Types of heterobimetallic catalysis

In synergistic catalysis

Complexes of palladium catalyze cross-coupling of electrophiles with organometallic nucleophiles, including those derived from lithium, tin, zinc, and boron. [3] One example is Sonogashira coupling, where catalytic amount of copper salt (e.g. CuI) reacts with a terminal alkyne (the pronucleophile) under basic conditions to generate a copper acetylide, which transmetalates onto an arylpalladiumII halide, regenerating the copper halide. Reductive elimination from the arylpalladium acetylide yields the cross-coupled product. [2]

Reaction-mechanism-v3.png

Other organic pronucleophiles are cross-coupled with arylpalladium halides in the following examples (Scheme 2):

1. Gold-catalyzed cyclization of allenoates followed by cross-coupling with aryl iodides yields 4-arylbutenolides [4]

2. Borylcupration of styrenes followed by palladium-catalyzed cross-coupling with aryl halides generates α-aryl-β-boromethyl functionalized arenes. [5] [6] This reaction has been rendered diastereoselective in the case of cyclic styrenes, [7] and an enantioselective variant has also been developed. [8] Enantioselective hydroarylation of styrenes is accomplished similarly via a chiral copper hydride [9]

3. Asymmetric conjugate reduction-allylation of α,β-unsaturated ketones is achieved by Cu-H mediated reduction and subsequent allylation via a chiral PHOX-ligated palladium catalyst [10]

Alternative pronucleophiles employed in synergistic heterobimetallic catalysis Pronuc.gif
Alternative pronucleophiles employed in synergistic heterobimetallic catalysis

Also of note is the enantioselective allylation of activated nitriles (Scheme 3). [11] A chiral bisphosphine-ligated rhodium catalyst activates the alpha-keto-nitrile component as its corresponding enolate, which is intercepted by a π-allylpalladium complex to yield the α-allylated nitrile in high enantiomeric excess. In the absence of the rhodium catalyst no enantioselectivity is observed, whereas the reaction does not proceed in the absence of palladium.

Scheme 3: Asymmetric allylation of nitrles with a heterobimetallic Rh/Pd catalyst system Allylation with Rh-Pd.gif
Scheme 3: Asymmetric allylation of nitrles with a heterobimetallic Rh/Pd catalyst system

With preformed heterobimetallic catalysts

Catalyst systems in which both metal centers are contained in the same complex are also known (e.g. Shibasaki catalysts); further examples are provided below.

Ion-paired combinations of early and late transition metal complexes can simultaneously interact with a substrate as both Lewis acid and Lewis base. [2] For example, carbonylative ring expansion of epoxides (Scheme 4) [12] [13] [14] is accomplished by Lewis acid activation by cationic complexes of CrIII, TiIII or AlIII with simultaneous ring opening by the [Co(CO)4]− counterion. Carbonylation of the resultant alkylcobalt followed by lactonization releases the product.

Scheme 4: Carbonylation of epoxides catalyzed by a heterobimetallic ion pair Carbonylation IonPair.gif
Scheme 4: Carbonylation of epoxides catalyzed by a heterobimetallic ion pair

A heterobimetallic bond-breaking process is also employed in the IPrCuFp-catalyzed C-H borylation system developed by Mankad (Scheme 5). [15] Bimetallic cleavage of the B-H bond in pinacolborane generates a copper hydride (IPrCu-H) and an iron boryl [(pin)B-Fp], the latter of which borylates unactivated arenes upon UV irradiation. Bimetallic reductive elimination of H2 from the combination of H-Fp and IPrCu-H restarts the catalytic cycle. The incorporation of copper into the catalyst is essential; C-H borylation using (pin)B-Fp alone is stoichiometric in iron due to dimerization of the HFp byproduct.

Scheme 5: UV-promoted C-H borylation of arenes catalyzed by IPrCuFp Mankad Borylation.gif
Scheme 5: UV-promoted C-H borylation of arenes catalyzed by IPrCuFp

Heterobimetallic catalysts containing persistent M1-M2 bonds exhibit altered reactivity due to interaction of the two different metal centers. For example, allylic amination catalyzed by the binuclear complex [Cl2Ti(NtBuPPh2)2-/Pd(η3-CH2C(CH3)CH2)]+ is exceptionally rapid. [16] DFT studies suggest that a Pd→Ti dative interaction accelerates the typically slow reductive elimination step by withdrawing electron density from Pd in the transition state [17] (Scheme 6).

Scheme 6: Pd/Ti-catalyzed allylic amination with accelerated reductive elimination due to a Pd-to-Ti dative interaction Pd Ti Allylation.gif
Scheme 6: Pd/Ti-catalyzed allylic amination with accelerated reductive elimination due to a Pd-to-Ti dative interaction

Silica-supported heterobimetallic tantalum iridium catalysts were shown exhibit drastically increased catalytic performances in H/D catalytic exchange reactions with respect to (i) monometallic analogues as well as (ii) homogeneous systems. [18] The key transition state in the C-H activation pathway, computed by DFT, involves (i) donation from the C-H σ orbital to an empty d orbital on the electrophilic early metal (Ta) together with (ii) backdonation from a filled d orbital arising from the late metal (Ir) to the C-H σ* orbital for nucleophilic assistance (Scheme 7). The calculations have shown that steric effects imparted by the ancillary ligands could result in enormous differences in C-H activation energy barriers (ca. 20 kcal/mol-1) in this heterobimetallic cooperative mechanism, indicating that metals accessibility has a drastic impact on the catalytic performances. [19]


Scheme 7: C-H activation promoted by a heterobimetallic tantalum iridium catalyst Camp heterobimetallic tantalum iridium C-H bond activation.gif
Scheme 7: C-H activation promoted by a heterobimetallic tantalum iridium catalyst

In photoredox catalysis

The combination of photoredox catalysis with traditional transition metal catalysis enables the use of visible light to drive challenging steps in a catalytic cycle. [20] For example, nickel-catalyzed aryl amination suffers from a difficult C-N reductive elimination step. [20] Hence instead of nickel, expensive palladium-based precatalysts are often used in combination with sterically-encumbered phosphine ligands to facilitate reductive elimination. [20] A more recent approach employs an iridium-based photoredox catalyst to effect single-electron oxidation of the intermediate NiII-amido complex. The resulting NiIII-amido rapidly undergoes reductive elimination, [20] allowing the Ni-catalyzed aryl amination to proceed at room temperature without the use of phosphine ligands.

Scheme 8: Ni-catalyzed aryl amination driven by oxidation of Ni(II) to Ni(III) via photoredox catalysis Photoredox Amination.gif
Scheme 8: Ni-catalyzed aryl amination driven by oxidation of Ni(II) to Ni(III) via photoredox catalysis

Biological significance

Enzymes containing two or more different metal centers are found in several important biological systems; for example, the Mo-Fe protein of nitrogenase [21] catalyzes the conversion of N2 to NH3 in nitrogen fixation. Of more relevance to human biology, Cu-Zn superoxide dismutase protects cells from oxidative stress by converting superoxide, O2−, to O2 and hydrogen peroxide [22]

Related Research Articles

The Heck reaction is the chemical reaction of an unsaturated halide with an alkene in the presence of a base and a palladium catalyst to form a substituted alkene. It is named after Tsutomu Mizoroki and Richard F. Heck. Heck was awarded the 2010 Nobel Prize in Chemistry, which he shared with Ei-ichi Negishi and Akira Suzuki, for the discovery and development of this reaction. This reaction was the first example of a carbon-carbon bond-forming reaction that followed a Pd(0)/Pd(II) catalytic cycle, the same catalytic cycle that is seen in other Pd(0)-catalyzed cross-coupling reactions. The Heck reaction is a way to substitute alkenes.

The Suzuki reaction is an organic reaction, classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide and the catalyst is a palladium(0) complex. It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of palladium-catalyzed cross-couplings in organic synthesis. This reaction is also known as the Suzuki–Miyaura reaction or simply as the Suzuki coupling. It is widely used to synthesize polyolefins, styrenes, and substituted biphenyls. Several reviews have been published describing advancements and the development of the Suzuki reaction. The general scheme for the Suzuki reaction is shown below, where a carbon-carbon single bond is formed by coupling a halide (R1-X) with an organoboron species (R2-BY2) using a palladium catalyst and a base.

The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst as well as copper co-catalyst to form a carbon–carbon bond between a terminal alkyne and an aryl or vinyl halide.

Organopalladium chemistry is a branch of organometallic chemistry that deals with organic palladium compounds and their reactions. Palladium is often used as a catalyst in the reduction of alkenes and alkynes with hydrogen. This process involves the formation of a palladium-carbon covalent bond. Palladium is also prominent in carbon-carbon coupling reactions, as demonstrated in tandem reactions.

<span class="mw-page-title-main">Wacker process</span>

The Wacker process or the Hoechst-Wacker process refers to the oxidation of ethylene to acetaldehyde in the presence of palladium(II) chloride as the catalyst. This chemical reaction was one of the first homogeneous catalysis with organopalladium chemistry applied on an industrial scale.

The Ullmann condensation or Ullmann-type reaction is the copper-promoted conversion of aryl halides to aryl ethers, aryl thioethers, aryl nitriles, and aryl amines. These reactions are examples of cross-coupling reactions.

<span class="mw-page-title-main">Palladium(II) acetate</span> Chemical compound

Palladium(II) acetate is a chemical compound of palladium described by the formula [Pd(O2CCH3)2]n, abbreviated [Pd(OAc)2]n. It is more reactive than the analogous platinum compound. Depending on the value of n, the compound is soluble in many organic solvents and is commonly used as a catalyst for organic reactions.

In organic chemistry, the Buchwald–Hartwig amination is a chemical reaction for the synthesis of carbon–nitrogen bonds via the palladium-catalyzed coupling reactions of amines with aryl halides. Although Pd-catalyzed C-N couplings were reported as early as 1983, Stephen L. Buchwald and John F. Hartwig have been credited, whose publications between 1994 and the late 2000s established the scope of the transformation. The reaction's synthetic utility stems primarily from the shortcomings of typical methods for the synthesis of aromatic C−N bonds, with most methods suffering from limited substrate scope and functional group tolerance. The development of the Buchwald–Hartwig reaction allowed for the facile synthesis of aryl amines, replacing to an extent harsher methods while significantly expanding the repertoire of possible C−N bond formation.

<span class="mw-page-title-main">Hydroamination</span> Addition of an N–H group across a C=C or C≡C bond

In organic chemistry, hydroamination is the addition of an N−H bond of an amine across a carbon-carbon multiple bond of an alkene, alkyne, diene, or allene. In the ideal case, hydroamination is atom economical and green. Amines are common in fine-chemical, pharmaceutical, and agricultural industries. Hydroamination can be used intramolecularly to create heterocycles or intermolecularly with a separate amine and unsaturated compound. The development of catalysts for hydroamination remains an active area, especially for alkenes. Although practical hydroamination reactions can be effected for dienes and electrophilic alkenes, the term hydroamination often implies reactions metal-catalyzed processes.

<span class="mw-page-title-main">Liebeskind–Srogl coupling</span>

The Liebeskind–Srogl coupling reaction is an organic reaction forming a new carbon–carbon bond from a thioester and a boronic acid using a metal catalyst. It is a cross-coupling reaction. This reaction was invented by and named after Jiri Srogl from the Academy of Sciences, Czech Republic, and Lanny S. Liebeskind from Emory University, Atlanta, Georgia, USA. There are three generations of this reaction, with the first generation shown below. The original transformation used catalytic Pd(0), TFP = tris(2-furyl)phosphine as an additional ligand and stoichiometric CuTC = copper(I) thiophene-2-carboxylate as a co-metal catalyst. The overall reaction scheme is shown below.

<span class="mw-page-title-main">DuPhos</span> Class of chemical compounds

DuPhos is a class of organophosphorus compound that are used ligands for asymmetric synthesis. The name DuPhos is derived from (1) the chemical company that sponsored the research leading to this ligand's invention, DuPont and (2) the compound is a diphosphine ligand type. Specifically it is classified as a C2-symmetric ligand, consisting of two phospholanes rings affixed to a benzene ring.

Metal carbon dioxide complexes are coordination complexes that contain carbon dioxide ligands. Aside from the fundamental interest in the coordination chemistry of simple molecules, studies in this field are motivated by the possibility that transition metals might catalyze useful transformations of CO2. This research is relevant both to organic synthesis and to the production of "solar fuels" that would avoid the use of petroleum-based fuels.

<span class="mw-page-title-main">PEPPSI</span> Group of chemical compounds

PEPPSI is an abbreviation for pyridine-enhanced precatalyst preparation stabilization and initiation. It refers to a family of commercially available palladium catalysts developed around 2005 by Prof. Michael G. Organ and co-workers at York University, which can accelerate various carbon-carbon and carbon-heteroatom bond forming cross-coupling reactions. In comparison to many alternative palladium catalysts, Pd-PEPPSI-type complexes are stable to air and moisture and are relatively easy to synthesize and handle.

<span class="mw-page-title-main">White catalyst</span> Chemical compound

The White catalyst is a transition metal coordination complex named after the chemist by whom it was first synthesized, M. Christina White, a professor at the University of Illinois. The catalyst has been used in a variety of allylic C-H functionalization reactions of α-olefins. In addition, it has been shown to catalyze oxidative Heck reactions.

The Tsuji–Trost reaction is a palladium-catalysed substitution reaction involving a substrate that contains a leaving group in an allylic position. The palladium catalyst first coordinates with the allyl group and then undergoes oxidative addition, forming the π-allyl complex. This allyl complex can then be attacked by a nucleophile, resulting in the substituted product.

Decarboxylative cross coupling reactions are chemical reactions in which a carboxylic acid is reacted with an organic halide to form a new carbon-carbon bond, concomitant with loss of CO2. Aryl and alkyl halides participate. Metal catalyst, base, and oxidant are required.

<span class="mw-page-title-main">Alkene carboamination</span>

Alkene carboamination is the simultaneous formation of C–N and C–C bonds across an alkene. This method represents a powerful strategy to build molecular complexity with up to two stereocenters in a single operation. Generally, there are four categories of reaction modes for alkene carboamination. The first class is cyclization reactions, which will form a N-heterocycle as a result. The second class has been well established in the last decade. Alkene substrates with a tethered nitrogen nucleophile have been used in these transformations to promote intramolecular aminocyclization. While intermolecular carboamination is extremely hard, people have developed a strategy to combine the nitrogen and carbon part, which is known as the third class. The most general carboamination, which takes three individual parts and couples them together is still underdeveloped.

Dialkylbiaryl phosphine ligands are phosphine ligands that are used in homogeneous catalysis. They have proved useful in Buchwald-Hartwig amination and etherification reactions as well as Negishi cross-coupling, Suzuki-Miyaura cross-coupling, and related reactions. In addition to these Pd-based processes, their use has also been extended to transformations catalyzed by nickel, gold, silver, copper, rhodium, and ruthenium, among other transition metals.

<span class="mw-page-title-main">Mizoroki-Heck vs. Reductive Heck</span>

The Mizoroki−Heck coupling of aryl halides and alkenes to form C(sp2)–C(sp2) bonds has become a staple transformation in organic synthesis, owing to its broad functional group compatibility and varied scope. In stark contrast, the palladium-catalyzed reductive Heck reaction has received considerably less attention, despite the fact that early reports of this reaction date back almost half a century. From the perspective of retrosynthetic logic, this transformation is highly enabling because it can forge alkyl–aryl linkages from widely available alkenes, rather than from the less accessible and/or more expensive alkyl halide or organometallic C(sp3) synthons that are needed in a classical aryl/alkyl cross-coupling.

<span class="mw-page-title-main">Nitro-Mannich reaction</span>

The nitro-Mannich reaction is the nucleophilic addition of a nitroalkane to an imine, resulting in the formation of a beta-nitroamine. With the reaction involving the addition of an acidic carbon nucleophile to a carbon-heteroatom double bond, the nitro-Mannich reaction is related to some of the most fundamental carbon-carbon bond forming reactions in organic chemistry, including the aldol reaction, Henry reaction and Mannich reaction.

References

  1. ↑ Schindler, C.; Jacobsen, E. (May 2013). "A New Twist on Cooperative Catalysis". Science. 340 (6136): 1052–1053. Bibcode:2013Sci...340.1052S. doi:10.1126/science.1238769. PMID   23723222. S2CID   35756570.
  2. 1 2 3 Pye, D.; Mankad, N. (March 2017). "Bimetallic catalysis for C–C and C–X coupling reactions". Chemical Science. 8 (3): 1705–1718. doi: 10.1039/c6sc05556g . PMC   5933431 . PMID   29780450.
  3. ↑ Organic Synthesis using Transition Metals Rod Bates ISBN   978-1-84127-107-1
  4. ↑ García-Domínguez, P.; Nevado, C. (March 2016). "Au–Pd Bimetallic Catalysis: The Importance of Anionic Ligands in Catalyst Speciation". J. Am. Chem. Soc. 138 (10): 3266–3269. doi:10.1021/jacs.5b10277. PMID   26952216.
  5. ↑ Semba, K.; Nakao, Y. (May 2014). "Arylboration of Alkenes by Cooperative Palladium/Copper Catalysis". J. Am. Chem. Soc. 136 (21): 7567–7570. doi:10.1021/ja5029556. PMID   24810227.
  6. ↑ Smith, K. B.; Logan, K. M.; You, W.; Brown, M. K. (August 2014). "Alkene carboboration enabled by synergistic catalysis". Chem. Eur. J. 20 (38): 12032–12036. doi:10.1002/chem.201404310. PMID   25113669.
  7. ↑ Logan, K. M.; Smith, K. B.; You, W.; Brown, M. K. (April 2015). "Copper/Palladium Synergistic Catalysis for the syn‐ and anti‐Selective Carboboration of Alkenes". Angew. Chem. Int. Ed. 54 (17): 5228–5231. doi:10.1002/anie.201500396. PMID   25727074.
  8. ↑ Jia, T.; Cao, P.; Wang, B.; Lou, Yazhou; Yin, X.; Wang, M.; Liao, J. (October 2015). "A Cu/Pd Cooperative Catalysis for Enantioselective Allylboration of Alkenes". J. Am. Chem. Soc. 137 (43): 13760–13763. doi:10.1021/jacs.5b09146. PMID   26458555.
  9. ↑ Friis, S. D.; Pirnot, M. T.; Buchwald, S. L. (June 2016). "Asymmetric Hydroarylation of Vinylarenes Using a Synergistic Combination of CuH and Pd Catalysis". J. Am. Chem. Soc. 138 (27): 8372–8375. doi: 10.1021/jacs.6b04566 . PMC   5010014 . PMID   27346525.
  10. ↑ Nahra, F.; Mac'e, Y.; Riant, O. (February 2013). "Copper/Palladium‐Catalyzed 1,4 Reduction and Asymmetric Allylic Alkylation of α,β‐Unsaturated Ketones: Enantioselective Dual Catalysis". Angew. Chem. Int. Ed. 52 (11): 3208–3212. doi:10.1002/anie.201208612. PMID   23382027.
  11. ↑ Sawamura, M.; Sudoh, M.; Ito, Y. (April 1996). "An Enantioselective Two-Component Catalyst System: Rh−Pd-Catalyzed Allylic Alkylation of Activated Nitriles". J. Am. Chem. Soc. 118 (137): 3309–3310. doi:10.1021/ja954223e.
  12. ↑ Schmidt, J. A. R.; Lobkovsky, E. B.; Coates, G. W. (July 2005). "Chromium (III) octaethylporphyrinato tetracarbonylcobaltate: a highly active, selective, and versatile catalyst for epoxide carbonylation". J. Am. Chem. Soc. 127 (32): 11426–11435. doi:10.1021/ja051874u. PMID   16089471.
  13. ↑ Yutan, D. Y. L. Getzler; Mahadevan, V.; Lobkovsky, E. B.; Coates, G. W. (January 2002). "Synthesis of β-Lactones: A Highly Active and Selective Catalyst for Epoxide Carbonylation". J. Am. Chem. Soc. 124 (7): 1174–1175. doi:10.1021/ja017434u. PMID   11841278.
  14. ↑ Mulzer, M.; Whiting, B.; Coates, G. W. (June 2013). "Regioselective Carbonylation of trans-Disubstituted Epoxides to β-Lactones: A Viable Entry into syn-Aldol-Type Products". J. Am. Chem. Soc. 135 (30): 10930–10933. doi: 10.1021/ja405151n . PMID   23790074.
  15. ↑ Mankad, N. (December 2013). "Non-Precious Metal Catalysts for C-H Borylation Enabled by Metal–Metal Cooperativity". Synlett. 25 (9): 1197–1201. doi:10.1055/s-0033-1340823. S2CID   196774326.
  16. ↑ Tsutsumi, H; Sunada, Y.; Shiota, Y.; Yoshizawa, K.; Nagashima, H. (March 2009). "Nickel(II), Palladium(II), and Platinum(II) η3-Allyl Complexes Bearing a Bidentate Titanium(IV) Phosphinoamide Ligand: A Ti←M2 Dative Bond Enhances the Electrophilicity of the π-Allyl Moiety". Organometallics. 28 (7): 1988–1991. doi:10.1021/om8011085.
  17. ↑ Walker, W. K.; Kay, B. M.; Michaelis, S.A.; Anderson, D. L.; Smith, S.J.; Ess, D. H.; Michaelis, D.J. (2015). "Origin of Fast Catalysis in Allylic Amination Reactions Catalyzed by Pd-Ti Heterobimetallic Complexes". Journal of the American Chemical Society. 137 (23): 7371–7378. doi:10.1021/jacs.5b02428. PMID   25946518.
  18. ↑ Lassalle, S.; Jabbour, R.; Schiltz, P.; Berruyer, P.; Todorova, T. K.; Veyre, L.; Gajan, D.; Lesage, A.; Thieuleux, C.; Camp, C. (2019). "Metal–Metal Synergy in Well-Defined Surface Tantalum–Iridium Heterobimetallic Catalysts for H/D Exchange Reactions". Journal of the American Chemical Society. 141 (49): 19321–19335. doi:10.1021/jacs.9b08311. PMID   31710215. S2CID   207944756.
  19. ↑ Del Rosal, I.; Lassalle, S.; Dinoi, C.; Thieuleux, C.; Maron, L.; Camp, C. (2021). "Mechanistic investigations via DFT support the cooperative heterobimetallic C–H and O–H bond activation across TaIr multiple bonds" (PDF). Dalton Transactions. 50: 504–510. doi:10.1039/D0DT03818K. PMID   33210676. S2CID   227064747.
  20. 1 2 3 4 Corcoran, E. B.; Pirnot, M. T.; Lin, S.; Dreher, S. D.; DiRocco, D. A.; Davies, I. W.; Buchwald, S. L. (July 2016). "Aryl amination using ligand-free Ni(II) salts and photoredox catalysis". Journal of the American Chemical Society. 353 (6296): 279–283. Bibcode:2016Sci...353..279C. doi: 10.1126/science.aag0209 . PMC   5027643 . PMID   27338703.
  21. ↑ Burges BK, Lowe DJ (1996). "Mechanism of Molybdenum Nitrogenase". Chemical Reviews . 96 (7): 2983–3011. doi:10.1021/cr950055x. PMID   11848849.
  22. ↑ Richardson J, Thomas KA, Rubin BH, Richardson DC (Apr 1975). "Crystal structure of bovine Cu,Zn superoxide dismutase at 3 A resolution: chain tracing and metal ligands". Proceedings of the National Academy of Sciences of the United States of America. 72 (4): 1349–53. doi: 10.1073/pnas.72.4.1349 . PMC   432531 . PMID   1055410..
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.