The mechanisms of oxidation of NADH analogues 3. Stimulated nuclear polarization (SNP) and chemically induced dynamic nuclear polarization (CIDNP) in low magnetic fields in photo-oxidation reactions of 1,4-dihydropyridines with quinones

Which Hydrogen Atom Is First Transferred in the NAD(P)H Model Hantzsch Ester Mediated Reactions via One-Step and Multistep Hydride Transfer?

“…sequence is still interesting and debatable in NAD(P)H model mediated reductions. Since the hydrogen atom at the 1 position is connected with the nitrogen atom, and the hydrogen atom at the 4 position is associated with a carbon atom, one could believe that the hydrogen at the 1 position should be transferred more easily than that at the 4 position during the aromatization of Hantzsch esters, especially initiated by one-electron transfer . In this paper, we choose ( Z )-ethyl α -cyano- β -bromomethylcinnamate and its analogue ( 1 ) as a probe to investigate the mechanism of the aromatization of HEH under thermal and photoexcited conditions by using isotope tracer experiments.…”

Photo‐CIDNP Study of the Interaction of Tyrosine with Nifedipine. An Attempt to Model the Binding Between Calcium Receptor and Calcium Antagonist Nifedipine¶

“…It is our suggestion that the interaction between NF and Tyr could involve an elementary step of the single‐electron transfer. In addition to the above theoretical considerations, this assumption has a number of experimental grounds because NF molecule incorporates both the nitrophenyl and dihydropyridine functions, whereas the nitroaromatics ( 8,9 ) and dihydropyridine ring ( 10–12 ) have known to enter the single‐electron transfer reactions with electron donors and acceptors, respectively.…”

“…Therefore, the use of the photo‐CIDNP method to generate the paramagnetic species and to study the detailed mechanisms of their transformations appears to be well founded. The CIDNP technique has been chosen because it is an extremely effective tool to study the mechanisms of complex chemical reactions involving paramagnetic intermediates ( 13, 14 ), in particular, the reactions of analogous 1,4‐dihydropyridines with various electron acceptors ( 10–12 ) and nitroaromatics with alcohols in solution ( 8 ). In addition, the application of TR CIDNP technique will allow to detect the polarizations manifested only by those diamagnetic products stemming from radical stages, thus revealing the targeted processes even in the presence of potent competing reaction pathway‐the direct phototransformation of NF to NONF.…”

One-Electron Reduction of 3,3,6,6-Tetramethyl-3,4,6,7,9,10-hexahydro-(1,8)-(2H,5H)-acridinedione: A Pulse Radiolysis Study

“…In fact the acridinediones have been shown to mimic NADH to a greater extent than the 1,4-dihydropyridines because of the tricyclic structure, which is capable of protecting the enamine moiety . There have been extensive studies on the photochemistry and electrochemistry of the 1,4-dihydropyridines. − We have previously carried out the electrochemical studies on various substituted acridinedione dyes . The studies reveal that these compounds undergo stepwise two-electron oxidation to form the products.…”