150787-21-6Relevant articles and documents
Regioreversed thermal and photochemical reduction of 10-methylacridinium and 1-methylquinolinium ions by organosilanes and oraganostannanes
Fukuzumi,Fujita,Noura,Ohkubo,Suenobu,Araki,Ito
, p. 1857 - 1868 (2001)
Irradiation of the absorption band of the 10-methylacridinium ion (AcrH+) in acetonitrile containing allylic silanes and stannanes results in the efficient and selective reduction of the 10-methylacridinium ion to yield the allylated dihydroacridines. In the photochemical reactions of AcrH+ with unsymmetric allylsilanes, the allylic groups are introduced selectively at the α position. Likewise, the reactions with unsymmetric allylstannanes afforded the α adducts predominantly, but the γ adducts were also obtained as minor products. In contrast to this, the thermal reduction of AcrH+ and the 1-methylquinolinium ion (QuH+) by unsymmetric allylstannanes gave only the γ adducts. The thermal reduction of QuH+ by tributyltin hydride or hydrosilanes in the presence of a fluoride anion also occurs to yield 1-methyl-1,2-dihydroquinoline selectively. On the other hand, the photoreduction of QuH+ derivatives by tributyltin hydride and tris(trimethylsilyl)silane yields the corresponding 1,4-dihydroquinolines exclusively. The difference in the mechanisms for the regioreversed thermal and photochemical reduction of AcrH+ and QuH+ is discussed in terms of nucleophilic vs electron-transfer pathways. The photochemical reactions proceed via photoinduced electron transfer from organosilanes and organostannanes to the singlet excited states of AcrH+ and QuH+, followed by the radical coupling of the resulting radical pair in competition with the back electron transfer to the ground state. The rate constants of photoinduced electron transfer obtained from the fluorescence quenching of AcrH+ and QuH+ by organosilane and organostannane donors agree with those obtained from the dependence of the quantum yields on the donor concentrations for the photochemical reactions. The electron-transfer rate constants are well analyzed in light of the Marcus theory of adiabatic outer-sphere electron transfer, leading to the evaluation of the reorganization energy (λ = 0.90 eV) of the electron-transfer reactions. The transient spectra of the radical pair produced by the photoinduced electron transfer from organosilanes to the singlet excited state of AcrH+ have been successfully detected in laser-flash photolysis of the AcrH+-organosilane systems. The rate constants of back electron transfer to the ground state have been determined, leading to the evaluation of the reorganization energy for the back electron transfer, which agrees with the value for the forward electron transfer.
No Significant Stereoelectronic Effects of Isopropyl Group in Photoaddition of Alkylbenzene Derivatives with 10-Methylacridinium Ion via Photoinduced Electron Transfer
Fujita, Morifumi,Fukuzumi, Shunichi
, p. 1528 - 1529 (1993)
The isopropyl group has no significant stereoelectronic effect no inter- and intra-molecular competition in deprotonation from alkylbenzene radical cations in the photoaddition of alkylbenzene derivatives with 10-methylacridinium ion via photoinduced elec
Cleavage mode of benzyltributylstannane radical cations produced in photoinduced electron transfer
Fukuzumi, Shunichi,Yasui, Kiyomi,Itoh, Shinobu
, p. 161 - 162 (1997)
Cleavage of metal-carbon bond of benzyltributylstannane radical cation produced in photoinduced electron transfer from benzyltributylstannane to 10-methylacridinium ion occurs to give benzyl radical rather than benzyl cation, resulting in formation of 9-benzyl-10-methyl-9,10-dihydroacridine selectively in dehydrated acetonitrile. In the presence of water, however, 10-methyl-9,10-dihydroacridine is also formed via electron transfer from benzyl radical to the dihydroacridine radical cation produced by protonation of acridinyl radical following the initial photoinduced electron transfer.
Addition versus oxygenation of alkylbenzenes with 10-methylacridinium ion via photoinduced electron transfer
Fujita, Morifumi,Ishida, Akito,Takamuku, Setsuo,Fukuzumi, Shunichi
, p. 8566 - 8574 (2007/10/03)
Addition of alkylbenzenes with 10-methylacridinium ion (AcrH+) occurs efficiently under visible light irradiation in deaerated acetonitrile containing H2O to yield 9-alkyl-10-methyl-9,10-dihydroacridine selectively. On the other hand, the photochemical reaction of AcrH+ with alkylbenzenes in the presence of perchloric acid in deaerated acetonitrile yields 10-methyl-9,10-dihydroacridine, accompanied by the oxygenation of alkylbenzenes to the corresponding benzyl alcohols. The photooxygenation of alkylbenzenes occurs also in the presence of oxygen, when AcrH+ acts as an efficient photocatalyst. The studies on the quantum yields and fluorescence quenching of AcrH+ by alkylbenzenes as well as the laser flash photolysis have revealed that the photochemical reactions of AcrH+ with alkylbenzenes in both the absence and presence of oxygen proceed via photoinduced electron transfer from alkylbenzenes to the singlet excited state of AcrH+ to produce alkylbenzene radical cations and 10-methylacridinyl radical (AcrH·). The competition between the deprotonation of alkylbenzene radical cations and the back electron transfer from AcrH· to the radical cations determines the limiting quantum yields. In the absence of oxygen, the coupling of the deprotonated radicals with AcrH· yields the adducts. The photoinduced hydride reduction of AcrH+ in the presence of perchloric acid proceeds via the protonation of acridinyl radical produced by the photoinduced electron transfer from alkylbenzenes. In the presence of oxygen, however, the deprotonated radicals are trapped efficiently by oxygen to give the corresponding peroxyl radicals which are reduced by the back electron transfer from AcrH· to regenerate AcrH+, followed by the protonation to yield the corresponding hydroperoxide. The ratios of the deprotonation reactivity from different alkyl groups of alkylbenzene radical cations were determined from both the intra- and intermolecular competitions of the deprotonation from two alkyl groups of alkylbenzene radical cations. The reactivity of the deprotonation from alkylbenzene radical cations increases generally in the order methyl ethyl isopropyl. The strong stereoelectronic effects on the deprotonation from isopropyl group of alkylbenzene radical cations appear in the case of the o-methyl isomer.
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.
