56875-26-4Relevant academic research and scientific papers
Importance of proton-coupled electron transfer in cathodic regeneration of organic hydrides
Ilic, Stefan,Alherz, Abdulaziz,Musgrave, Charles B.,Glusac, Ksenija D.
, p. 5583 - 5586 (2019)
Electrochemical regeneration of organic hydrides is often hindered by the rapid dimerization of organic radicals produced as the first intermediates of these electrochemical transformations. In this work, we utilize proton-coupled electron transfer to outcompete the undesired dimerization and achieve successful hydride regenerations of two groups of organic hydrides-acridines and benzimidazoles. This work provides an analysis of the critical factors that control the regeneration pathways of organic hydrides.
Direct Arylation of Distal and Proximal C(sp3)-H Bonds of t-Amines with Aryl Diazonium Tetrafluoroborates via Photoredox Catalysis
Mondal, Pradip Kumar,Tiwari, Sandip Kumar,Singh, Pushpendra,Pandey, Ganesh
, p. 17184 - 17196 (2021/12/02)
A visible light-mediated arylation protocol for t-amines has been reported through the coupling of γ- and α-amino alkyl radicals with different aryl diazonium salts using Ru(bpy)3Cl2·6H2O as a photocatalyst. Structurally different 9-aryl-9,10-dihydroacridine, 1-aryl tetrahydroisoquinoline, hexahydropyrrolo[2,1-a]isoquinoline, and hexahydro-2H-pyrido[2,1-a]isoquinoline frameworks with different substitution patterns have been synthesized in good yield using this methodology.
Hydride Transfer from Iron(II) Hydride Compounds to NAD(P)+ Analogues
Zhang, Fanjun,Jia, Jiong,Dong, Shuli,Wang, Wenguang,Tung, Chen-Ho
, p. 1151 - 1159 (2016/06/01)
Iron(II) hydride complexes of the "piano-stool" type, Cp?(P-P)FeH (P-P = dppe (1H), dppbz (2H), dppm (3H), dcpe (4H)) were examined as hydride donors in the reduction of N-benzylpyridinium and acridinium salts. Two pathways of hydride transfer, "single-step H-" transfer to pyridinium and a "two-step (e-/H?)" transfer for acridinium reduction, were observed. When 1-benzylnicotinamide cation (BNA+) was used as an H- acceptor, kinetic studies suggested that BNA+ was reduced at the C6 position, affording 1,6-BNAH, which can be converted to the more thermally stable 1,4-product. The rate constant k of H- transfer was very sensitive to the bite angle of P-Fe-P in Cp?(P-P)FeH and ranged from 3.23 × 10-3 M-1 s-1 for dppe to 1.74 × 10-1 M-1 s-1 for dppm. The results obtained from reduction of a range of N-benzylpyridinium derivatives suggest that H- transfer is more likely to be charge controlled. In the reduction of 10-methylacridinium ion (Acr+), the reaction was initiated by an e- transfer (ET) process and then followed by rapid disproportionation reactions to produce Acr2 dimer and release of H2. To achieve H? transfer after ET from [Cp?(P-P)FeH]+ to acridine radicals, the bulkier acridinium salt 9-phenyl-10-methylacridinium (PhAcr+) was selected as an acceptor. More evidence for this "two-step (e-/H?)" process was derived from the characterization of PhAcr? and [4H]+ radicals by EPR spectra and by the crystallographic structure confirmation of [4H]+. Our mechanistic understanding of fundamental H- transfer from iron(II) hydrides to NAD+ analogues provides insight into establishing attractive bio-organometallic transformation cycles driven by iron catalysis.
C-H functionalization of azines. Anodic dehydroaromatization of 9-(hetero)aryl-9,10-dihydroacridines
Shchepochkin,Chupakhin,Charushin,Steglenko,Minkin,Rusinov,Matern
, p. 77834 - 77840 (2018/06/22)
Data on anodic dehydroaromatization of 9,10-dihydroacridines, bearing aryl and heteroaryl fragments, are presented. Effects of both electron-donating and electron-withdrawing substituents on the current-voltage characteristics of these compounds have been established. The experimental data proved to be in a good agreement with quantum chemical calculations. A simple and convenient method for the electrochemical conversion of dihydroacridines into the corresponding 9-(hetero)aryl-N-methylacridinium salts has been advanced.
A classical but new kinetic equation for hydride transfer reactions
Zhu, Xiao-Qing,Deng, Fei-Huang,Yang, Jin-Dong,Li, Xiu-Tao,Chen, Qiang,Lei, Nan-Ping,Meng, Fan-Kun,Zhao, Xiao-Peng,Han, Su-Hui,Hao, Er-Jun,Mu, Yuan-Yuan
, p. 6071 - 6089 (2013/09/12)
A classical but new kinetic equation to estimate activation energies of various hydride transfer reactions was developed according to transition state theory using the Morse-type free energy curves of hydride donors to release a hydride anion and hydride acceptors to capture a hydride anion and by which the activation energies of 187 typical hydride self-exchange reactions and more than thirty thousand hydride cross transfer reactions in acetonitrile were safely estimated in this work. Since the development of the kinetic equation is only on the basis of the related chemical bond changes of the hydride transfer reactants, the kinetic equation should be also suitable for proton transfer reactions, hydrogen atom transfer reactions and all the other chemical reactions involved with breaking and formation of chemical bonds. One of the most important contributions of this work is to have achieved the perfect unity of the kinetic equation and thermodynamic equation for hydride transfer reactions. The Royal Society of Chemistry.
Toward organic photohydrides: Excited-state behavior of 10-methyl-9-phenyl-9,10-dihydroacridine
Yang, Xin,Walpita, Janitha,Zhou, Dapeng,Luk, Hoi Ling,Vyas, Shubham,Khnayzer, Rony S.,Tiwari, Subodh C.,Diri, Kadir,Hadad, Christopher M.,Castellano, Felix N.,Krylov, Anna I.,Glusac, Ksenija D.
, p. 15290 - 15296 (2014/01/06)
The excited-state hydride release from 10-methyl-9-phenyl-9,10- dihydroacridine (PhAcrH) was investigated using steady-state and time-resolved UV/vis absorption spectroscopy. Upon excitation, PhAcrH is oxidized to the corresponding iminium ion (PhAcr
Direct regioselective phenylation of acridine derivatives by phenyllithium
Dutta, Bishnupada,Kar, Gandhi K.,Ray, Jayanta K.
, p. 8641 - 8643 (2008/04/18)
Acridine and acridine derivatives have been converted directly to phenyl derivatives regioselectively using phenyllithium.
The tightness contribution to the Bronsted α for hydride transfer between NAD+ analogues
Lee, In-Sook Han,Chow, Kim-Hung,Kreevoy, Maurice M.
, p. 7755 - 7761 (2007/10/03)
It has been shown that the rate of symmetrical hydride transfer reaction varies with the hydride affinity of the (identical) donor and acceptor. In that case, Marcus theory of atom and group transfer predicts that the Bronsted α depends on the location of the substituent, whether it is in the donor or the acceptor, and the tightness of the critical configuration, as well as the resemblance of the critical configuration to reactants or products. This prediction has now been confirmed for hydride transfer reactions between heterocyclic, nitrogen-containing cations, which can be regarded as analogues of the enzyme cofactor, nicotinamide adenine dinucleotide (NAD+). A series of reactions with substituents in the donor gives Bronsted α of 0.67 ± 0.03 and a tightness parameter, τ of 0.64 ± 0.06. With substituents in the acceptor α = 0.32 ± 0.03 and τ = 0.68 ± 0.08. The reactions are all spontaneous, with equilibrium constants between 0.4 and 3 x 104, and the two sets span about the same range of equilibrium constants. The two τ values are essentially identical with an average value of 0.66 ± 0.05. These results can be semiquantitatively mimicked by rate constants calculated for a linear, triatomic model of the reaction. Variational transition state theory and a physically motivated but empirically calibrated potential function were used. The computed rate constants generate an α value of 0.56 if the hydride affinity of the acceptor is varied and an α of 0.44 if the hydride affinity of the donor is varied. The calculated kinetic isotope effects are similar to the measured values. A previous error in the Born charging term of the potential function has been corrected. Marcus theory can be successfully fitted to both the experimental and computed rate constants, and appears to be the most compact way to express and compare them. The success of the linear triatomic model in qualitatively reproducing these results encourages the continued use of this easily conceptualized model to think about group, ion, and atom transfer reactions.
Steric and kinetic isotope effects in the deprotonation of cation radicals of NADH synthetic analogues
Anne, Agnès,Fraoua, Sylvie,Hapiot, Philippe,Moiroux, Jacques,Savéant, Jean-Michel
, p. 7412 - 7421 (2007/10/02)
The deprotonation rate constants and kinetic isotope effects of the cation radicals have been determined by combined use of direct electrochemical techniques at micro- and ultramicroelectrodes, redox catalysis, and laser flash photolysis, over a extended
Electron-transfer oxidation of 9-substituted 10-methyl-9,10-dihydroacridines. Cleavage of the C-H vs C-C bond of the radical cations
Fukuzumi, Shonichi,Tokuda, Yoshihiro,Kitano, Toshiaki,Okamoto, Toshihiko,Otera, Junzo
, p. 8960 - 8968 (2007/10/02)
Electron-transfer oxidation of various 9-substituted 10-methyl-9,10-dihydroacridines (AcrHR) by Fe(ClO4)3 and [Fe(phen)3](PF6)3 (phen = 1,10-phenanthroline) results in cleavage of the C(9)-H or C(9)-C bond of AcrHR?+ depending on the substituent R. Transient electronic absorption spectra as well as electron spin resonance (ESR) spectra of AcrHR?+ have been detected by using a stopped-flow spectrophotometer and a rapid mixing flow ESR technique, respectively. The hyperfine splitting constants (hfs) are determined by comparing the observed ESR spectra with those from the computer simulation. Comparison of the hfs values with those expected from the molecular orbital calculations indicates the structural change of AcrHR?+ with the substituent R, which is reflected in the selectivity of the C-H vs C-C bond cleavage of AcrHR?+ depending on the substituent R. The decay rates of AcrHR?+ obey the mixture of first-order and second-order kinetics due to the deprotonation (or the C-C bond cleavage) and disproportionation reactions, respectively. Both the first-order and bimolecular second-order decay rate constants of AcrHR?+ are reported. The first-order decay rate constant for the deprotonation of AcrHR?+ by the C-H bond cleavage decreases with the substitution in order R = primary > secondary > tertiary alkyl groups, while the first-order decay due to the C-C bond cleavage becomes dominant with tertiary alkyl groups. The one-electron oxidation potentials of various AcrHR have been determined directly by applying fast cyclic voltammetry. The pKa values of AcrHR?+ (R = H and Me) have also been evaluated by analyzing the dependence of the first-order deprotonation rate constants on the concentrations of HClO4.
