5096-13-9Relevant articles and documents
Macrocyclic Enzyme Model System. Kinetic Activity of Paracyclophane Bearing 1,4-Dihydronicotinamide and 2-Pyridinecarboxylic Acid Moieties as Effected by Zinc Ion
Murakami, Yukito,Aoyama, Yasuhiro,Kikuchi, Jun-ichi
, p. 2898 - 2901 (1982)
As regards the effect of zinc(II) ion on the reduction of hexachloroacetone, the kinetic activity of a paracyclophane (PCP) bearing 1,4-dihydronicotinamide (HNA) and 2-pyridinecarboxylic acid (Py) moieties, HNA-PCP-Py, has been investigated as an alcohol dehydrogenase model in reference to that of PCP-HNA in the light of their metal-coordination behavior.The reduction ability of PCP-HNA was significantly lowered as it underwent complex formation with zinc.On the other hand, HNA-PCP-Py showed an apparent rate maximum in a relatively lower concentration range of ZnCl2.The kinetic behavior was analyzed on the basis of the formation of two kinds of zinc complexes of HNA-PCP-Py: the 1:1 complex , in which both Py and HNA moieties are simultaneously coordinated to the same zinc ion, showed a decreased reactivity relative to metal-free HNA-PCP-Py; while the 2:1 complex (HNA-PCP-Py-ZnII-Py-PCP-HNA), in which HNA is free from metal-coordination, exercised a much enhanced activity, 7 times as reactive as metal-free HNA-PCP-Py.A plausible reaction mechanism for the enhanced reactivity has been discussed.
MECHANISM AND TRANSITION-STATE STRUCTURE OF HYDRIDE-TRANSFER REACTIONS MEDIATED BY NAD(P)H - MODELS
Verhoeven, J. W.,Gerresheim, W. van,Martens, F. M.,Kerk, S. M. van der
, p. 975 - 992 (1986)
The energy to transfer one electron from NAD(P)H and related 1,4-dihydropyridines to a series of substrates is calculated and compared with the experimental activation energy for transfer of a hydride equivalent between these species.It is concluded that single electron-transfer (SET) cannot occur as a primary step in the overall hydride-transfer process except for substrates with very strong one-electron oxidizing properties.A simple valence-bond configuration mixing (VBCM) model is presented, that rationalizes the general occurrence of concerted hydride transfer as the lowest energy reaction-pathway and furthermore explains why the activtion energy of such a concerted pathway is often linearly related to that of a -hypothetical- SET process.For one intramolecular and two related, intermolecular hydride-transfer reactions the temperature dependence of the primary kinetic isotope effect (TDKIE) was studied.For the intramolecular reaction, where a face to face orientation of the reactants is enforced, the TDKIE parameters suggest the occurence of a bent hydride-transfer pathway.For both intermolecular reactions, however, a linear transition-state geometry is indicated.MNDO calculations of the reaction profile for hydride transfer from a 1,4-dihydropyridine to either a positively charged substrate (i.e. the pyridinium-ion) or to a neutral substrate (i.e. 1,1-dicyanoethylene) confirm, that a linear transition-state geometry is favoured, unless the system is geometrically restrained to prevent such a geometry.The MNDO calculations furthermore indicate that in a linear transition-state almost unimpeded rotation can occur about the C...H...C axis.This rotation interconverts the relative orientation of the reactants between parallel-exo and tilted-endo, which may have important consequences for the interpretation of the stereochemical outcome of reactions involving (pro)chiral reactants.
Tandem synthesis of substituted 2,7-naphthyridin-1(7H)-ones via Reissert reaction/intramolecular nucleophilic addition/oxidation dehydrogenation
Tan, Hailiang,Wang, Jie,Zhang,Xing, Yongning,Sun, Qi,Li, Runtao
, p. 8299 - 8304 (2013/09/02)
A convenient method for the synthesis of substituted 2,7-naphthyridin-1(7H) -ones has been developed. This method was carried out starting from a simple nicotinamide salts via a tandem process including Reissert reaction, intramolecular nucleophilic addition and oxidation dehydrogenation. Using this method, a variety of substituted 2,7-naphthyridin-1(7H)-ones were obtained in good yields.
Synthesis of phenylene 1,3- and 1,4-bis(methylene)-3-carbamoylpyridinium bromides
Zhou, Feng,Wang, Chi-Hua,Warner, John C.
, p. 173 - 177 (2007/10/03)
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