20637-05-2Relevant articles and documents
Efficient C-H Amination Catalysis Using Nickel-Dipyrrin Complexes
Betley, Theodore A.,Clarke, Ryan M.,Dong, Yuyang,Porter, Gerard J.
supporting information, p. 10996 - 11005 (2020/07/08)
A dipyrrin-supported nickel catalyst (AdFL)Ni(py) (AdFL: 1,9-di(1-adamantyl)-5-perfluorophenyldipyrrin; py: pyridine) displays productive intramolecular C-H bond amination to afford N-heterocyclic products using aliphatic azide substrates. The catalytic amination conditions are mild, requiring 0.1-2 mol% catalyst loading and operational at room temperature. The scope of C-H bond substrates was explored and benzylic, tertiary, secondary, and primary C-H bonds are successfully aminated. The amination chemoselectivity was examined using substrates featuring multiple activatable C-H bonds. Uniformly, the catalyst showcases high chemoselectivity favoring C-H bonds with lower bond dissociation energy as well as a wide range of functional group tolerance (e.g., ethers, halides, thioetheres, esters, etc.). Sequential cyclization of substrates with ester groups could be achieved, providing facile preparation of an indolizidine framework commonly found in a variety of alkaloids. The amination cyclization reaction mechanism was examined employing nuclear magnetic resonance (NMR) spectroscopy to determine the reaction kinetic profile. A large, primary intermolecular kinetic isotope effect (KIE = 31.9 ± 1.0) suggests H-atom abstraction (HAA) is the rate-determining step, indicative of H-atom tunneling being operative. The reaction rate has first order dependence in the catalyst and zeroth order in substrate, consistent with the resting state of the catalyst as the corresponding nickel iminyl radical. The presence of the nickel iminyl was determined by multinuclear NMR spectroscopy observed during catalysis. The activation parameters (ΔH? = 13.4 ± 0.5 kcal/mol; ΔS?= -24.3 ± 1.7 cal/mol·K) were measured using Eyring analysis, implying a highly ordered transition state during the HAA step. The proposed mechanism of rapid iminyl formation, rate-determining HAA, and subsequent radical recombination was corroborated by intramolecular isotope labeling experiments and theoretical calculations.
Reductive C-C Coupling by Desulfurizing Gold-Catalyzed Photoreactions
Zhang, Lumin,Si, Xiaojia,Yang, Yangyang,Witzel, Sina,Sekine, Kohei,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
, p. 6118 - 6123 (2019/07/03)
[Au2(μ-dppm)2]Cl2-mediated photocatalysis reactions are usually initiated by ultraviolet A (UVA) light; herein, an unreported system using blue light-emitting diodes (LEDs) as excitation light source was found. The red shift of the absorption wavelength originates from the combination of [Au2(μ-dppm)2]Cl2 and ligand (Ph3P or mercaptan). On the basis of this finding, a gold-catalyzed reductive desulfurizing C-C coupling of electrophilic radicals and styrenes mediated by blue LEDs is presented, a coupling which cannot be efficiently accessed by previously reported methods. This mild and highly efficient C-C bond formation strategy uses mercaptans both as electron-deficient alkyl radical precursor as well as the hydrogen source. Two examples of amino acids have also been modified by using this strategy. Moreover, this methodology could be applied in polymer synthesis. Gram-scale synthesis and mechanistic insights into this transformation are also presented.
Direct Manipulation of Metal Imido Geometry: Key Principles to Enhance C-H Amination Efficacy
Baek, Yunjung,Hennessy, Elisabeth T.,Betley, Theodore A.
supporting information, p. 16944 - 16953 (2019/10/19)
We report the catalytic C-H amination mediated by an isolable CoIII imido complex (TrL)Co(NR) supported by a sterically demanding dipyrromethene ligand (TrL = 5-mesityl-1,9-(trityl)dipyrrin). Metalation of (TrL)
Metal-Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent-Iodine-Promoted Oxidative C?C Bond Formation
Shimogaki, Mio,Fujita, Morifumi,Sugimura, Takashi
supporting information, p. 15797 - 15801 (2016/12/16)
The enantioselective oxyarylation of (E)-6-aryl-1-silyloxylhex-3-ene was achieved using a lactate-based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved.
2,3,4-Trihydroxybenzyl-hydrazide analogues as novel potent coxsackievirus B3 3C protease inhibitors
Kim, Bo-Kyoung,Ko, Hyojin,Jeon, Eun-Seok,Ju, Eun-Seon,Jeong, Lak Shin,Kim, Yong-Chul
, p. 202 - 216 (2016/05/24)
Human coxsackievirus B3 (CVB3) 3C protease plays an essential role in the viral replication of CVB3, which is a non-enveloped and positive single-stranded RNA virus belonging to Picornaviridae family, causing acute viral myocarditis mainly in children. During optimization based on SAR studies of benserazide (3), which was reported as a novel anti-CVB3 3Cpro agent from a screening of compound libraries, the 2,3,4-trihydroxybenzyl moiety of 3 was identified as a key pharmacophore for inhibitory activity against CVB3 3Cpro. Further optimization was performed by the introduction of various aryl-alkyl substituted hydrazide moieties instead of the serine moiety of 3. Among the optimized compounds, 11Q, a 4-hydroxyphenylpentanehydrazide derivative, showed the most potent inhibitory activity (IC50 Combining double low line 0.07 μM). Enzyme kinetics studies indicated that 11Q exhibited a mixed inhibitory mechanism of action. The antiviral activity against CVB3 was confirmed using the further derived analogue (14b) with more cell permeable valeryl ester group at the 2,3,4-trihydroxy moiety.
Pharmacophore-based discovery, synthesis, and biological evaluation of 4-phenyl-1-arylalkyl piperidines as dopamine transporter inhibitors
Sakamuri, Sukumar,Enyedy, Istvan J,Kozikowski, Alan P,Zaman, Wahiduz A,Johnson, Kenneth M,Wang, Shaomeng
, p. 495 - 500 (2007/10/03)
Pharmacophore-based discovery, synthesis, and structure-activity relationship (SAR) of a series of 4-phenyl-1-arylalkyl piperidines are disclosed. These compounds have been evaluated for their ability to inhibit reuptake of dopamine (DA) into striatal nerve endings (synaptosomes). The lead compound 5 and the most potent analogue 43 were found to have significant functional antagonism.
