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Structural Design for Molecular Catalysts
Published in Qingmin Ji, Harald Fuchs, Soft Matters for Catalysts, 2019
Qingmin Ji, Qin Tang, Jonathan P. Hill, Katsuhiko Ariga
Various ligands have been employed for the Cu center, to enhance its reactivity, selectivity, and stability. Several privileged ligand structures have proven to be extremely versatile and useful ligands, especially iminopyridines, which show particular effectiveness in stereoselective transformations such as nitroaldol reactions, allylic oxidations, and conjugate additions. Chelucci et al. evaluated the catalytic efficiency of Cu complexes with chiral iminopyridine ligands in carbene (cyclopropanation) and nitrene transfer reactions (aziridination, C–H amidation) [47]. They found that a better catalytic performance can be achieved for nitrene transfers, particularly in the amidation of C–H bonds.
Cyclopentane Construction by Rh-Catalyzed Intramolecular C-H Insertion
Published in Dale W. Blackburn, Catalysis of Organic Reactions, 2020
Douglass F. Taber, Michael J. Hennessy, R. Scott Hoerrne, Krishna Raman, Robert E. Ruckle, Jonathan S. Schuchardt
Total synthesis of the primary prostaglandins, despite the many advances that have been recorded over the last 20 years,25 is still a lengthy undertaking. The observation that even with the availability of β-hydride, the rhodium carbenoid derived from a simple α-diazoketone will efficiently do 1,5 C-H insertion, suggested that such simple rhodium carbenoids might also be effective for intramolecular cyclopropanation. This has now been shown26 to be the case.
N-Heterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
Korkowski et al. [19] studied cyclopropanes in carbocyclic systems. They observed that a stoichiometric amount (1.2 eq.) of Fischer carbene complex was required for cyclopropanation. Another study concluded that the metathesis product is formed in good yields when the alkene is substituted with a phenyl group (Scheme 3) [20].
Rhodium catalysis in the synthesis of fused five-membered N-heterocycles
Published in Inorganic and Nano-Metal Chemistry, 2020
Navjeet Kaur, Neha Ahlawat, Yamini Verma, Pranshu Bhardwaj, Pooja Grewal, Nirmala Kumari Jangid
The alkaloids (±)-horsfiline and (±)-strychnofoline[164,165] were synthesized by this strategy. Carbenoid (237) was produced from a rhodium(II)-catalyzed decomposition of 3-diazoisatin (236). Later on Carreira et al.[166] performed cyclopropanation of pyperilene employing carbenoid for the construction of spiro-cyclopropaneoxindole (237) and ring-expansion using imine (238) to afford spiro-pyrrolidine-oxindole (239) which was used in the preparation of spirotryprostatin B (240) (Scheme 56).[167]
Anticancer, antimicrobial and antiparasitical activities of copper(I) complexes based on N-heterocyclic carbene (NHC) ligands bearing aryl substituents
Published in Journal of Coordination Chemistry, 2020
Nedra Touj, Ibrahim S. Al Nasr, Waleed S. Koko, Tariq A. Khan, Ismail Özdemir, Sedat Yasar, Lamjed Mansour, Faisal Alresheedi, Naceur Hamdi
N-heterocyclic carbene ligands have been proven very popular in the last 20 years. Conjugate reduction of α,β-unsaturated ketones and esters, the hydrosilylation of ketones, the cyclopropanation of terminal alkenes, as well as olefinations, carbene transfer reactions, aziridination of olefins and methylenation of aldehydes are among some examples of the uses of Cu-NHC complexes (specifically (IPr) CuCl) in modern catalysis. Finally, these catalysts are air- and moisture-stable and they can be used as precursors to synthesize more air-sensitive complexes [53].