- From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
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The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
- De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
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p. 133 - 147
(2021/05/10)
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- Substrate Profiling of the Cobalt Nitrile Hydratase from Rhodococcus rhodochrous ATCC BAA 870
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The aromatic substrate profile of the cobalt nitrile hydratase from Rhodococcus rhodochrous ATCC BAA 870 was evaluated against a wide range of nitrile containing compounds (>60). To determine the substrate limits of this enzyme, compounds ranging in size from small (90 Da) to large (325 Da) were evaluated. Larger compounds included those with a biaryl axis, prepared by the Suzuki coupling reaction, Morita–Baylis–Hillman adducts, heteroatomlinked diarylpyridines prepared by Buchwald–Hartwig crosscoupling reactions and imidazo[1,2a]pyridines prepared by the Groebke–Blackburn–Bienaymé multicomponent reaction. The enzyme active site was moderately accommodating, accepting almost all of the small aromatic nitriles, the diarylpyridines and most of the biaryl compounds and Morita–Baylis–Hillman products but not the Groebke–Blackburn–Bienaymé products. Nitrile conversion was influenced by steric hindrance around the cyano group, the presence of electron donating groups (e.g., methoxy) on the aromatic ring, and the overall size of the compound.
- Mashweu, Adelaide R.,Chhiba‐Govindjee, Varsha P.,Bode, Moira L.,Brady, Dean
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- Radical Anions of Aromatic Carbonitriles as Reagents for Arylation of Fluorinated Benzonitriles
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The first example of phenylation of fluorobenzonitriles with the sodium salt of a benzonitrile radical anion in liquid ammonia is presented. The reaction regioselectivity corresponds to the ortho- and para-fluorine atom substitution in fluorobenzonitrile with the phenyl moiety of the benzonitrile radical anion and affords 2- and 4-cyanobiphenyls in 40-90% yields. 3-Methoxybenzonitrile as well as 1-cyanonaphthalene radical anions were also successfully subjected to this interaction forming 3′-methoxycyanobiphenyls and (1-naphthyl)benzonitriles, respectively. The radical anion acts as an ipso-C-nucleophile with consequent loss of the cyano group. The revealed new type of radical anion reactivity opens up the prospect of developing a general approach to fluorinated cyanobisarenes on the basis of an interaction of the cyanoarene radical anion with fluorinated substrates activated to aromatic nucleophilic substitution.
- Peshkov, Roman Yu.,Wang, Chunyan,Panteleeva, Elena V.,Rybalova, Tatyana V.,Tretyakov, Evgeny V.
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- Radical Anions of Aromatic Carbonitriles as Reagents for Arylation of Fluorinated Benzonitriles
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The first example of phenylation of fluorobenzonitriles with the sodium salt of a benzonitrile radical anion in liquid ammonia is presented. The reaction regioselectivity corresponds to the ortho- and para-fluorine atom substitution in fluorobenzonitrile with the phenyl moiety of the benzonitrile radical anion and affords 2- and 4-cyanobiphenyls in 40-90% yields. 3-Methoxybenzonitrile as well as 1-cyanonaphthalene radical anions were also successfully subjected to this interaction forming 3′-methoxycyanobiphenyls and (1-naphthyl)benzonitriles, respectively. The radical anion acts as an ipso-C-nucleophile with consequent loss of the cyano group. The revealed new type of radical anion reactivity opens up the prospect of developing a general approach to fluorinated cyanobisarenes on the basis of an interaction of the cyanoarene radical anion with fluorinated substrates activated to aromatic nucleophilic substitution.
- Panteleeva, Elena V.,Peshkov, Roman Yu.,Rybalova, Tatyana V.,Tretyakov, Evgeny V.,Wang, Chunyan
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p. 963 - 972
(2021/08/24)
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- CATHEPSIN C INHIBITORS
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Disclosed are 3-aminopyrrolidines of Formula (I) having pharmacological activity, pharmaceutical compositions containing them, and methods for the treatment of diseases mediated by the cathepsin C enzyme such as chronic obstructive pulmonary disease.
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Page/Page column 44
(2011/04/14)
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- Structure-based design of new DHFR-based antibacterial agents: 7-aryl-2,4-diaminoquinazolines
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Dihydrofolate reductase (DHFR) inhibitors such as trimethoprim (TMP) have long played a significant role in the treatment of bacterial infections. Not surprisingly, after decades of use there is now bacterial resistance to TMP and therefore a need to develop novel antibacterial agents with expanded spectrum including these resistant strains. In this study, we investigated the optimization of 2,4-diamnoquinazolines for antibacterial potency and selectivity. Using structure-based drug design, several 7-aryl-2,4- diaminoquinazolines were discovered that have excellent sub-100 picomolar potency against bacterial DHFR. These compounds have good antibacterial activity especially on gram-positive pathogens including TMP-resistant strains.
- Li, Xiaoming,Hilgers, Mark,Cunningham, Mark,Chen, Zhiyong,Trzoss, Michael,Zhang, Junhu,Kohnen, Lucy,Lam, Thanh,Creighton, Chris,Gc, Kedar,Nelson, Kirk,Kwan, Bryan,Stidham, Mark,Brown-Driver, Vickie,Shaw, Karen J.,Finn, John
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scheme or table
p. 5171 - 5176
(2011/10/09)
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- Palladium nanoparticles on graphite oxide and its functionalized graphene derivatives as highly active catalysts for the Suzuki-Miyaura coupling reaction
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Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, and catalyst morphology on the catalytic activity in the Suzuki-Miyaura coupling reactions was investigated. The catalysts were characterized by means of spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), and electron microscopy (TEM, ESEM). In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39 000 h-1, accompanied by very low palladium leaching (1 ppm).
- Scheuermann, Gil M.,Steurer, Peter,Muelhaupt, Rolf,Rumi, Luigi,Bannwarth, Willi
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supporting information; experimental part
p. 8262 - 8270
(2009/11/30)
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- Excitatory amino acid receptor antagonists
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The present invention provides novel compounds of Formula (I), or the pharmaceutically acceptable salts or prodrugs thereof, and methods for treating neurological disorders and neurodegenerative diseases, particularly pain and migraine.
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