74309-54-9Relevant academic research and scientific papers
Photoenzymatic Hydrogenation of Heteroaromatic Olefins Using ‘Ene’-Reductases with Photoredox Catalysts
Biegasiewicz, Kyle F.,Black, Michael J.,Chung, Megan M.,Hyster, Todd K.,Meichan, Andrew J.,Nakano, Yuji,Sandoval, Braddock A.,Zhu, Tianyu
, p. 10484 - 10488 (2020/04/29)
Flavin-dependent ‘ene’-reductases (EREDs) are highly selective catalysts for the asymmetric reduction of activated alkenes. This function is, however, limited to enones, enoates, and nitroalkenes using the native hydride transfer mechanism. Here we demonstrate that EREDs can reduce vinyl pyridines when irradiated with visible light in the presence of a photoredox catalyst. Experimental evidence suggests the reaction proceeds via a radical mechanism where the vinyl pyridine is reduced to the corresponding neutral benzylic radical in solution. DFT calculations reveal this radical to be “dynamically stable”, suggesting it is sufficiently long-lived to diffuse into the enzyme active site for stereoselective hydrogen atom transfer. This reduction mechanism is distinct from the native one, highlighting the opportunity to expand the synthetic capabilities of existing enzyme platforms by exploiting new mechanistic models.
Pyridine-directed asymmetric hydrogenation of 1 1-diarylalkenes
Yang, Hailong,Wang, Erfei,Yang, Ping,Lv, Hui,Zhang, Xumu
supporting information, p. 5062 - 5065 (2017/11/07)
Highly enantioselective pyridine-directed rhodium-catalyzed asymmetric hydrogenation of challenging 1 1-diarylalkenes is achieved by using [Rh(NBD)DuanPhos]BF4 as a precatalyst. Various types of 2-pyridine substituted 1 1-diarylalkenes could be hydrogenated with good to excellent enantioselectivities which provide an efficient route to the synthesis of pharmaceutically and biologically active compounds containing a 2-pyridyl ethane unit.
Palladium-Catalyzed Divergent Arylation with Triazolopyridines: One-Pot Synthesis of 6-Aryl-2-α-styrylpyridines
Moon, Youngtaek,Kwon, Soonhyung,Kang, Dahye,Im, Honggu,Hong, Sungwoo
supporting information, p. 958 - 964 (2016/04/05)
We have developed a new strategy for palladium-catalyzed arylation reactions with triazolopyridines, wherein two different chemical transformations (C-3 vs. C-7) are observed by differentiating the substrates using different bases. The reactive palladium carbenoids were directly generated from triazolopyridines and underwent denitrogenative arylations with aryl bromides. Intriguingly, when potassium carbonate was replaced with potassium tert-butoxide, direct C-H arylation occurred at the most acidic position (C-7). Moreover, two different catalytic arylation events were successfully performed in a one-pot sequence, providing a convenient access to 6-aryl-2-α-styrylpyridines.
Rhodium-Catalyzed Cyanation of C(sp2)-H Bond of Alkenes
Chaitanya, Manthena,Anbarasan, Pazhamalai
supporting information, p. 3766 - 3769 (2015/08/18)
Efficient and selective rhodium-catalyzed cyanation of chelation-assisted C-H bonds of alkenes has been accomplished using environmentally benign N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS) as a cyanating reagent. The developed methodology tolerates various functional groups and allows the synthesis of diverse substituted acrylonitriles in good to excellent yields. Furthermore, the potential of the methodology was demonstrated through the formal synthesis of chlorpheniramine-based antagonist.
Copper-catalyzed α-methylenation of benzylpyridines using dimethylacetamide as one-carbon source
Itoh, Masaki,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
supporting information, p. 2050 - 2053 (2014/05/06)
The direct α-methylenation of benzylpyridines was achieved using N,N-dimethylacetamide (DMA) as a one-carbon source under copper catalysis. An intermediary species was detected at an early stage, and a possible mechanism was proposed. Additionally, α-oxygenation and dimerization of benzylpyridines could also be performed efficiently.
Kinetic Energy Release and Position of Transition State during Intramolecular Aromatic Substitution in Ionized 1-Phenyl-1-(2-pyridyl)ethylenes
Schubert, Ralf,Gruetzmacher, Hans-Friedrich
, p. 5323 - 5328 (2007/10/02)
The loss of substituents (X = H, CH3, Cl, Br, I) from the molecular ions of ortho-substituted 1-phenyl-1-(2-pyridyl)ethylenes 1a-f and of the isomeric 1-phenyl-1-(3-pyridyl)- and 1-phenyl-1-(4-pyridyl)ethylenes 2 and 3 has been investigated.Cyclic fragment ions a are formed from the ortho-substituted 1-phenyl-1-(2-pyridyl)ethylene molecular ions by an intramolecular aromatic substitution reaction.The energetic requirements of this reaction have been studied in dependence from the dissociation energy of the C-X bond by measurements of the ionization energies, appearance energies, and kinetic energies released during the reaction.The activation energy εh of the process varies only slightly with the dissociation energy of the C-X bond cleaved during the reaction, whereas the entalpy of reaction changes from positive (endothermic) to very negative (exothermic) values in the reaction series 1a-f.Consequently the reverse activation energy εr ranges from small to very large values in this series.This trend in εr is not followed by the kinetic-energy release.A large kinetic-energy release and energy partitioning quotient q = 0.7 - 1.0 is only observed for endothermic or thermoneutral processes, while a small kinetic-energy release and q ca. 0.2 is associated with exothermic reactions in spite of a large εr.This behavior has been correlated to the position Xo* of the transition state on the reaction coordinate according to Miller's quantification of the Hammond postulate.The release of εr as kinetic energy is only observed for reactions with "symmetrical" or "late" transition states (Xo* > 0.4) while most of εr remains as internal energy in the products of reactions with "early" transition states (Xo* 0.4).
