70083-49-7Relevant articles and documents
Intramolecular kinetic isotope effect in hydride transfer from dihydroacridine to a quinolinium ion. Rejection of a proposed two-step mechanism with a kinetically significant intermediate
Perrin, Charles L.,Zhao, Chen
supporting information; experimental part, p. 3349 - 3353 (2009/02/05)
The intramolecular kinetic isotope effect (KIE) for hydride transfer from 10-methyl-9,10-dihydroacridine to 1-benzyl-3-cyanoquinolinium ion has been found to be 5-6 by both 1H NMR and mass spectrometry. This KIE is consistent with other hydride transfers. It is inconsistent with the high intermolecular KIEs derived by fitting to a two-step mechanism with a kinetically significant intermediate complex, and it is inconsistent with the strong temperature dependence of those KIEs. We therefore reject the two-step mechanism for this reaction, and we suggest that other cases proposed to follow this mechanism are in error.
Marcus Theory of Hydride Transfer from an Anionic reduced Deazaflavin to NAD+ Analogues
Lee, In-Sook Han,Ostovic, Drazen,Kreevoy, Maurice
, p. 3989 - 3993 (2007/10/02)
Eighteen rate constants, kij for hydride transfer from the conjugate base of 1,5-dihydro-3,10-dimethyl-5-diazaisoalloxazine to a variety of pyridinium, quinolinium, phenanthridinium, and acridinium ions have been determined. (All the oxidizing agents can be regarded as analogues of NAD+.) The kij values span 7 powers of 10 and the corresponding equilibrium constants, Kij, span more than 13 powers of 10.For reactions with ΔG0 near zero, the kij values are close to those given by modified Marcus theory (ref 10).However, with more negative ΔG0 values, the observed kij increase more strogly than the calculated values.Agreement can be produced by making the standard free energy of precursor complex formation, symbolized WT +- here, to indicate that it applies to reactants of opposite charge, a linear function of ΔG0, and treating the slope and interrcept of the linear relation as adjustable parameters.The best fit is obtained with WT+-(in kJ*mol-1)=-9.4+0.11ΔG0.An avarage discrepancy between calculated and observed ln kij values of 0.5 is achieved, which is a good as the overall fit achieved for hydride transfer from neutral NADH analogues to NAD+ analogues (ref 10).The form and the parameterization of Wf are shown to be a physically reasonable approximation for reactions with ΔG00.These results strengthen the conclusion (ref 10) that a wide range of hydride transfer rates can be quantitavely understood without introducing high-energy metastable intermediates (radicals and radical ions).
Regioselectivity of Hydride Transfer to and between NAD+ Analogues
Roberts, R. M. G.,Ostovic, D.,Kreevoy, M. M.
, p. 2053 - 2056 (2007/10/02)
The reaction of 1-methyl- or 1-benzylquinolinium compounds, also bearing an electron-withdrawing substituent in the 3-position, with NaBH4, gives mixtures of the corresponding 1,2-dihydroquinolines and 1,4-dihydroquinolines in which the 1,2-dihydro derivatives usually predominate.The 1,2-derivatives can be isolated.The 1,2-isomers react with the quinolinium salts, giving the 1,4-isomers and regenerating quinolinium salts.This bimolecular isomerization can be used to convert a mixture of isomers to the 1,4-isomer on a preparative scale. 3-Cyano-1,2-dihydro-1-methylquinoline also isomerizes to the 1,2-isomer in the crystalline solid.The major first product of NaBH4 reduction of 3-(aminocarbonyl)-1-benzylpyridinium ion is the 1,6-dihydro derivative.This also isomerizes to the 1,4-dihydro compound in the presence of the pyridinium ion.Reduction of quinolinium derivatives with Na2S2O4 or a dihydropyridine directly produces the 1,4-isomer predominantly.Reduction of 3-(aminocarbonyl)-1-benzylpyridinium ion with Na2S2O4 in D2O gives the 1,4-dihydro derivative, but 8percent of the deuterium is in the 2-position; presumably by reversible isomerization.This deuterium redistribution may have important consequences for the interpretation of isotope effects.
