85749-96-8Relevant academic research and scientific papers
Regioselectivity and Kinetics of Hydride Transfer in Substituted 1-Benzyl-3-quinolinecarboxamide Redox Reactions
Romoff, Todd T.,Sampson, Nicole S.,Eikeren, Paul van
, p. 4454 - 4459 (2007/10/02)
A systematic study on the factors that affect the regioselectivity and rate of hydride transfer in systems involving 1-benzyl-4-methyl-3-quinolinecarboxamides as donors or acceptors is reported.The study reports two major findings: (1) Hydride transfers from borohydride or 1-propyl-1,4-dihydronicotinamide to 1-benzyl-4-methyl-3-quinolinecarboxamide cation display distinct regioselective patterns-borohydride results in hydride transfer to the 2-position of the acceptor and dihydronicotinamide results in hydride transfer to the 4-position of the acceptor. (2) Substitution of the 4-hydrogen by a methyl group on either the oxidant or reductant quinoline lowers the rate constants for hydride transfer by a factor of over 2000.When methyl replaces hydrogen in both the oxidant and reductant, the rate constant for hydride transfer is lowered by a factor of over 5 000 000.These observations are interpreted in terms of a two-step mechanism: (1) formation of a ?-complex between the oxidant and reductant stabilized by charge-transfer interactions and (2) rate-determining hydride transfer within the complex.
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.
