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The Use of Small Particle Catalysts in Pursuit of Green and Sustainable Chemistry
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
The iterative process prescribed for small-molecule drug discovery requires an appraisal and extension of existing knowledge to select new molecules as targets for synthesis and testing leading to molecules designed for improved treatment properties.138 Clearly, the existing knowledge of a catalyst support’s content and composition is important in a normative role for the construction of synthetic pathways.139 The analysis of the chemical synthesis landscape for modern medicinal chemistry, discerned from the medicinal chemistry literature, identified a limited number of reactions dominating academic and industrial practice.140 The economics of this information for the industry is quite important since the progression of a drug-discovery process can be expensive and time-consuming. With a process development duration constrained by the number of cycles of design, synthesis, and testing needed to improve the properties of successive generations of small molecules to match the various criteria required for the product candidate selection, it is necessary to conduct this investigation with optimal economic guidance.141,142 The most common reactions found through the literature analysis were the Suzuki–Miyaura chemistry, amide bond formation, and a reduction of heterocyclic syntheses for the timeframes evaluated. Breakthrough synthetic transformations, such as ring-closing metathesis, C-H bond activation, or biocatalysis among other candidates, did not show comparable impact in the record of use. The cross-coupling reaction has become a workhorse for the pharmaceutical industry and despite its age, a series of modifications have simplified operations and reduced the reaction’s environmental footprint.143
Principles of Green Chemistry
Published in Sanjay K. Sharma, Hasan Demir, Green Chemistry in Scientific Literature, 2019
The Suzuki cross-coupling reaction has fewer limitations and is environmentally friendly, efficient, and highly useful for the drug industry, compared to Heck reaction, Kumada, Stille, Negishi, and Sonogashiri coupling reactions (Franzén and Xu 2005). The Mannich reaction leads to the production of amino carbonyl compounds, and 1,2-amino alcohol derivatives have been satisfactorily achieved in water (Iwanejko, Wojaczyńska, and Olszewski 2018). Friedel-Crafts alkylation has also another greener process with new approaches that gained the attention of researchers in recent years. The new approach in Friedel-Crafts alkylation reaction allows using a low amount of catalyst. Additionally, benzyl-, propargyl- and allyl alcohols, or styrenes are started to be used instead of toxic benzyl halides (Rueping and Nachtsheim 2010). Catalytic nanoreactors provide operation of organic reactions in aqueous medium, reducing environmental risks for obtaining chemical sustainability. De Martino et al., (2018) reviewed E-factors of traditional and nanoreactor catalytic reactions in the pharmaceutical industry as shown in Figure 3.10. E-factors of reactions in the pharmaceutical industry decreased significantly using micellar nanoreactors. The advantages of nanoreactors, which are polymersomes, micelles, dendrimers, and nanogels, can be explained as: Promotion of cascade reactions Generation of hydrophobic materials in aqueous and greener conditions Easy recovery of catalyst (De Martino et al. 2018)
Ceria-Based Nanocrystalline Oxide Catalysts: Synthesis, Characterization, and Applications
Published in Nandakumar Kalarikkal, Sabu Thomas, Obey Koshy, Nanomaterials, 2018
Anushka Gupta, v. Sai Phani Kumar, Manjusha Padole, Mallika Saharia, K. B. Sravan Kumar, Parag A. Deshpande
C—C bond formation is observed in many compounds important in biological, pharmaceutical, and material processing. Due to this, there is a need to develop mild and general methods for C-C coupling. The synthesis of these bonds involve nucleophillic aromatic substitution reactions which necessitate the use of electron deficient aryl halides. Several coupling reactions have been developed with different substrates. Most prevalent among these methods are the palladium (0) catalyzed cross coupling reactions namely Heck reaction,78 Sonogashira-Miyaura reaction,79 Suzuki-Miyaura reac- tion,80 and Hartwig-Buchwald coupling.81 These C-C coupling reactions allow a one-step synthesis of aromatic olefins which are used extensively as biologically active compounds, natural products, pharmaceuticals, and precursors of conjugated polymers. Products formed from C—C coupling reactions are the intermediates for various pharmaceutical products showing antimicrobial activity and antitumor effects. This makes the above reactions important. C—C coupling reactions proceed in the presence of homogeneous as well as heterogeneous catalysts. These reactions are catalyzed by palladium (Pd) supported on supports such as charcoal, mesoporous carbon, magnesium oxide, silica, alumina or titania, silica, and basic supports such as basic zeolites, mixed oxide, and flourapatite. Apart from palladium, Suzuki- Miyaura reaction has been catalyzed by several other transition metal complexes. Iron-MCPA complex has been recently reported to catalyze the reaction.82 Fe halides have been reported as catalysts for the reaction.83 Cu has also been used for catalyzing the reaction.83 Further bimetallic catalysts consisting of Cu along with Pd, Pt, and Ru have also been tested and found active for the reaction. Combined Cu/Pd catalyst was found to show the highest activity among all the combinations. Ni complex has also been used for the synthesis of biaryls using Suzuki-Miyaura reaction.84 But no study has been conducted on these C—C coupling reactions before investigation by Hegdeet al.3, 85 where they investigated the substitution of noble metal in reducible oxides such as CeO2 which showed higher catalytic activity than the homogeneous catalytic reactions. Overall, 100% conversions of the reactants was observed as shown in Figure 10.8.
Preparation and characterization of PEPPSI-palladium N-heterocyclic carbene complexes using benzimidazolium salts catalyzed Suzuki–Miyaura cross coupling reaction and their antitumor and antimicrobial activities
Published in Journal of Coordination Chemistry, 2019
Lamia Boubakri, Khaireddine Dridi, Abdullah Sulaiman Al-Ayed, İsmail Özdemir, Sedat Yasar, Naceur Hamdi
The synthesis of biaryl compounds presents a unique challenge to chemists. In the traditional reactions of organic chemistry, no methods exist for the efficient coupling of two different aromatic groups in a single reaction. There are possible synthetic routes to make biaryls, but the ability to complete such a transformation quickly and efficiently via catalyst could be a potentially powerful tool for organic synthesis. Many developments utilizing homo-coupling and cross-coupling reactions have been presented in the past few decades. A great number of in situ generated NHC-Pd catalysts have been reported in Suzuki cross-coupling reactions [26, 27]. Herrmann reported the first Pd-NHC catalyst used for Suzuki cross-coupling reaction in 2002 [28]. Then, Pd-PEPPSI (pyridine-enhanced precatalyst preparation stabilization and initiation) type Pd-NHC complexes have been extensively developed by Organ and co-workers for the cross-coupling of challenging, aryl-, and alkyl-electrophiles [29–36]. In particular, our research group has achieved important improvements in Suzuki–Miyaura cross-coupling reactions using PEPPSI complexes [49].
Catalytic C–C cross-coupling and hydrogen evolution by two Pd(II)-complexes of di-2-pyridyl ketone benzoyl hydrazones
Published in Journal of Coordination Chemistry, 2019
Mohammed Bakir, Mark W. Lawrence, Peter Nelson, M. Bohari Yamin
Palladium and its coordination compounds continue to attract research activities for their industrial [1–7], environmental [8–12], chemical [13–30], and biological relevance [26–30]. Pd-catalysts are widely used in organic synthesis to affect a variety of transformations that include C-H bond activation, cross-coupling reactions, hydrogenation/dehydrogenation, decarboxylation, carbonylation, aminocarbonylation, amidation, etc. [14–23]. Among the various types of Pd cross-coupling reactions, the Suzuki-Miyaura, Negishi, Mizoroki-Heck, Sonogashira, and Hiyama are the most powerful [16–21]. Pd coordination compounds of Schiff bases that include di-2-pyridyl imines such as 2,4,6-trimethyl-(di-2-pyridylmethylene)aniline and 2,6-di-isopropyl-(di-2-pyridylmethylene)aniline and ethanedial bis[methyl(pyridin-2-yl)hydrazone are of current interest due to their rich properties, resistance to oxidation reactions, and catalytic and medicinal applications [22–30]. Pd(II) complexes of chelating κ2-N,N-α-diimine and κ3-NNX-Schiff bases (X = N, O or S) exhibit cytotoxicity against various cancers and emerged as alternatives to Pt therapeutic agents due to their higher solubility, lower toxicity, and facile synthesis compared to Pt complexes [28–30]. In addition to the catalytic and therapeutic uses of Pd coordination compounds, Pd plays an important role in hydrogen economy for purification and storage of hydrogen and use in fuel cells [4–7]. The widespread use of Pd and its coordination compounds resulted in environmental and medicinal pollution that promoted research to develop highly sensitive reagents and analytical methods for sequestering, detection and determination of trace amounts of Pd due to its high toxicity [9, 10].
Bioactive NHC-derived palladium complexes: synthesis, catalytic activity for the Suzuki-Miyaura coupling of aryl chlorides and bromides and their antibacterial activities
Published in Journal of Coordination Chemistry, 2019
Lamia Boubakri, Abdullah S. Al-Ayed, L. Mansour, Nael Abutaha, Abdel Halim Harrath, I. Özdemir, S. Yasar, Naceur Hamdi
Cross-coupling reactions are important methods to produce fine chemicals in organic synthesis. Suzuki-Miyaura reaction is one of the most beneficial and studied C-C bond forming reactions due to its use of non-toxic chemicals, substrate tolerance, green solvents, mild reaction conditions and easy separation of product from reaction media [31, 32]. Some excellent reviews were published on this area [33].