Recent Applications of Palladium-Catalyzed Coupling Reactions in the Pharmaceutical, Agrochemical, and Fine Chemical Industries
TL;DR: Palladium-catalyzed coupling reactions have become a central tool for the synthesis of biologically active compounds both in academia and industry as discussed by the authors, and many of these transformations make use of easily available substrates and allow for a shorter and more selective preparation of substituted arenes and hetero-arenes compared to noncatalytic pathways.
Abstract: Palladium-catalyzed coupling reactions have become a central tool for the synthesis of biologically active compounds both in academia and industry. Most of these transformations make use of easily available substrates and allow for a shorter and more selective preparation of substituted arenes and heteroarenes compared to non-catalytic pathways. Notably, molecular-defined palladium catalysts offer high chemoselectivity and broad functional group tolerance. Considering these advantages, it is not surprising that several palladium-catalyzed coupling reactions have been implemented in the last decade into the industrial manufacture of pharmaceuticals and fine chemicals. In this review different examples from 2001-2008 are highlighted, which have been performed at least on a kilogram scale in the chemical and pharmaceutical industries.
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TL;DR: There is an optimum size for the NHC ligand that depends upon whether reactivity (turnover frequency and turnover number), selectivity, or both are needed to obtain the desired reaction outcome, and reactivity and selectivity increase together, allowing cross-couplings to be carried out under mild conditions to obtain one product with high selectivity.
Abstract: ConspectusOver the past decade, the use of Pd–NHC complexes in cross-coupling applications has blossomed, and reactions that were either not previously possible or possible only under very forcing conditions (e.g., > 100 °C, strong base) are now feasible under mild conditions (e.g., room temperature, weak base). Access to tools such as computational chemistry has facilitated a much greater mechanistic understanding of catalytic cycles, which has enabled the design of new NHC ligands and accelerated advances in cross-coupling. With these elements of rational design, highly reactive Pd–NHC complexes have been invented to catalyze the selective formation of single products in a variety of transformations that have the potential to afford multiple compounds (e.g., isomers).Pd–NHC catalysts may be prepared as stable Pd(II) precatalysts that are readily reduced to the active Pd(0) species in the presence of an organometallic cross-coupling partner or nucleophile possessing β-hydrogens. It has been found from co...
182 citations
TL;DR: Palladium nanoparticles supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide as discussed by the authors.
Abstract: Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide. CNXLs acted as both the reducing agent and support material for the obtained nanoparticles. Dry Pd nanoparticles supported on the cellulose nanocrystals (PdNP@CNXL) were obtained by simply venting the CO2 and were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The results show that the Pd nanoparticle diameters varied between 6 and 13 nm with varying pressure (240–2200 psi), reaction time (2–17 h), and weight ratio of the precursor Pd(hfac)2 to CNXL (1–4% w/w). Particles with diameters above 13 nm appeared not to remain attached to the CNXL surface. Reaction conditions also affected the Pd loading in the final PdNP@CNXL composite. Finally, the PdNP@CNXL composites were shown to ...
113 citations
TL;DR: The synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy, suggest that a "release and catch" mechanism is operative in both reactions, although during Heck reaction small catalytically active soluble Pd species are also present.
Abstract: We report the synthesis and catalytic properties of single-walled carbon nanotube—polyamidoamine dendrimers hybrids (SWCNT–PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4]2–, led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (TOF) of 566 000 h–1. In addition, the hybrid material could be recovered and recycled for up to 6 times. No leaching of the metal has been detected during the Suzuki coupling. Additional experiments carried out on the spent catalyst permitted to suggest that a “release and catch” mechanism is operative in both reactions, a...
104 citations
Cites background from "Recent Applications of Palladium-Ca..."
...pharmaceuticals, drugs, agrochemicals but also organic semiconductors.(19-21) Nevertheless, the...
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01 Jan 2013
TL;DR: A Historical Overview of Metal-Catalyzed Cross-Coupling Reactions is given in this article, along with applications of cross-coupling reactions in natural product synthesis and pharmaceuticals.
Abstract: Metal-Catalyzed Cross-Coupling Reactions.- A Historical Overview of Metal-Catalyzed Cross-Coupling Reactions.- Mechanism and Fundamental Reactions.- Applications of Cross-Coupling Reactions.- Natural Product Synthesis.- Pharmaceuticals.- Liquid Crystals.- Conjugated Polymers.- Recent Advances in Cross-Coupling Reactions.- With Aryl Chlorides, Tosylates, and Methylates.- With Alkyl Electrophiles.
84 citations
Cites methods from "Recent Applications of Palladium-Ca..."
...Additionally, the following are examples of total syntheses utilizing Sonogashira–Hagihara coupling reported after 2000: frondosin B [16], callipeltoside A [17], mucocin [18], borrelidin [19], tetrodotoxin [20], 34-hydroxyasimicin [21], oximidine II [22], (-)-siphonodiol, (-)-tetrahydrosiphonodiol [23], peroxyacarnoates A and D [24], leucascandrolide A [25], macbecin I [26], moracin O, moracin P [27] (+)-neopeltolide [28], furopyrans [29], leiodolide B [30], iso- and bongkrekic acids [31], cis- and trans- bupleurynol [32], and lukianol A [33]....
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...Historically, cross-couplings started in 1972 (date received, October 28, 1971) from the research of Corriu at Montpellier University, France using Grignard reagents (m = MgX) and a catalytic amount of Ni(acac)2 to construct carbon(sp (2))–carbon(sp(2)) bonds [16]....
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TL;DR: This review describes the isolation, brief biological activities and various synthetic methodologies developed during recent years for the preparation of this important class of alkaloids, with special emphasis on preparation and properties of cryptolepine 1, isocryptolepine 2 and neocryptolespine 3.
Abstract: The tetracyclic heteroaromatic compounds cryptolepine, isocryptolepine and neocryptolepine are all naturally occurring indoloquinoline alkaloids isolated from the shrub Cryptolepis sanguinolenta and are important due to their wide spectrum of biological properties. This review describes the isolation, brief biological activities and various synthetic methodologies developed during recent years for the preparation of this important class of alkaloids, with special emphasis on preparation and properties of cryptolepine 1, isocryptolepine 2 and neocryptolepine 3.
78 citations
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TL;DR: In this review different examples from 2001-2008 are highlighted, which have been performed at least on a kilogram scale in the chemical and pharmaceutical industries.
Abstract: Palladium-catalyzed coupling reactions have become a central tool for the synthesis of biologically active compounds both in academia and industry. Most of these transformations make use of easily available substrates and allow for a shorter and more selective preparation of substituted arenes and heteroarenes compared to non-catalytic pathways. Notably, molecular-defined palladium catalysts offer high chemoselectivity and broad functional group tolerance. Considering these advantages, it is not surprising that several palladium-catalyzed coupling reactions have been implemented in the last decade into the industrial manufacture of pharmaceuticals and fine chemicals. In this review different examples from 2001-2008 are highlighted, which have been performed at least on a kilogram scale in the chemical and pharmaceutical industries.
1,121 citations