N-Benzyl-l,4-dihydronicotinamide

The reduction of ( )-2-, ( )-3- and ( )-4-cinnamoylpyridines by 1,4-dihydropyridines to give dihydro ketones has also been shown to be catalyzed by zinc(II) and magnesium(II).527 Kinetic measurements show that the rate of reduction is fastest in the case of the 2-isomer where the metal is simultaneously complexed with the nitrogen and oxygen donors. A very fast zinc-catalyzed reduction of pyridine-2-carbaldehyde by the alcohol dehydrogenase coenzyme model JV,JV -diethyl-N-benzyl-l,4-dihydronicotinamide (170) has also been described.528... 

By means of stopped-flow spectrophotometry, the reaction of flavopapain IV withN-benzyl-l,4-dihydronicotinamide (NBzNH) has been studied anaerobically. Using conditions of excess substrate and following the decrease in absorbance of Eox (at 427 nm) with time, we observed biphasic kinetic behavior. The experimental data could be fitted to a scheme using two consecutive first-order processes, and rate constants could be determined for the two phases. A reasonable interpretation of our results is that a labile intermediate is formed in the reaction, as illustrated in Equation 4, where ES represents the intermediate. In this interpretation, the second, substrate-independent, slower phase of the reaction corresponds to the breakdown of the intermediate ES (fc3 step in Equation 4). The initial, faster phase of the reaction corresponds to the formation of the intermediate from Eox and N-benzyl-l,4-dihydronicotinamide. Using Equation 5, the calculated rate constants for this phase, fcf, can be related to Ks and k2- Values of kCat and Km were calculated from the relationships of Equations 6 and 7, using the measured values of the kinetic parameters k2, 3, and Ks, and the numbers obtained were in reasonable agreement with the values obtained aerobically. 

N-benzyl-l,4-dihydronicotinamide cat ClRh(PPh3)3 or Pd(OAc)2 (allylic, benzylic, aryl, vinylic)... 

EFFECT OF THE COUNTER ANION ON THE OXIDATION OF N-BENZYL-l,4-DIHYDRONICOTINAMIDE... 

In contrast with our results with the flavopapains III and V, we have found that flavopapain IV can act as an effective catalyst for the oxidation of dihydronicotinamides (13, 14). Using dihydronicotinamide in excess, the oxidation reactions of N-benzyl-, N-ethyl-, N-propyl- and N-hexyl-l,4-dihydronicotinamide as well as that of NADH by flavopapain IV exhibit saturation kinetics at relatively low substrate concentrations. This behavior contrasts with the oxidation by model flavins or flavopapains III and V, where saturation... 

In Table II, kcat/Km values for four naturally occurring flavoenzymes that utilize either NADH or NADPH as substrates are listed. Comparison of these data with those of Table I shows that the oxidation ofN-hexyl-l,4-dihydronicotinamide by flavopapain IV proceeds faster than the reaction illustrated for one of the enzymes, somewhat slower than those illustrated for two of the enzymes, and much slower than that observed for bovine-heart NADH dehydrogenase. The kcat/Km values measured for the reaction of N-hexyl-l,4-dihydronicotinamide as well as those for the N-benzyl-, N-ethyl-, and N-propyl compounds... 

In 5-bromouracil having no substituents on N-1, bromine is replaced by hydrogen on heating at 180 C with l-benzyl-l,4-dihydronicotinamide. Thus (25) yields (26), (27) and (28) (equation 61). ... 

Hydroxylation Induced during the Autoxidation of N-benzyl-1,4-dihydronicotinamide. Oxygen was bubbled through the aromatic compound suspended in an aqueous solution of N-benzyl-l,4-dihydronico-tinamide and ferric chloride. Four compounds were oxidized by this model system benzene to phenol and no biphenyl toluene to benzyl alcohol, cresols, phenol, and no bibenzyl anisole to phenol and methoxyphenols fluorobenzene to phenol and fluorophenols. Even under optimum... 

N-Alkylacridinium ions and other cationic heteroarenes likewise underwent photoalkylation, but these processes were reductive additions, rather than photosubstitution, yielding acridanes [46]. In these cases, both tetra-aUcylstarmanes and the more environmentally benign 4-aIkyl-l-benzyl-l,4-dihydronicotinamides have recently been used as a source of alkyl radicals [47]. 

Okada and Oda described an efficient method for PET-induced decarboxylation of non-activated carboxylic acids. When irradiated as the corresponding N-acyloxyphthalimide derivatives 68 in the presence of l,6-bis(dimethylamino)pyrene (BDMAP) as sensitizer and r-BuSH as hydrogen donor, the corresponding alkanes 69 were obtained in high to excellent yields of 78 to 98% (Scheme 25). The reaction could also be performed with visible light when a Ru(bpy)3Cl2/l-benzyl-l,4-dihydronicotinamide (BNAH) combination was used. ... 

Kashima et al. have explored the synthesis of N-1 substituted, C-2 unsubstituted dihydropyrimidines 39 and 40 through Raney-Ni induced desulfurization of N-1 derivatives 37 and 38 (Scheme 17) (83JCS(P1)1799). However, the 4,6-dimethyl-l-phenylpyrimidin-2-(lH)-thione required an H2 atmosphere at room temperature. The higher oxidation potential of these products than 1-benzyl 1,4-dihydronicotinamide (Ep = 0.700 V), showed their propensity to transfer hydride. Thus, the desulfurized DHPMs 39 as well as 40, reduced malachite green to its leuco derivative (83TL209). 

The following fluorescent probes were chosen as substrates N-phenyl-1-naphthylamine (PNA), 1-benzyl-1,4-dihydronicotinamide (BNAH), indole, indolyl-Sracetic acid, 8-anilinonaphthalene-l-sulfonate (ANS), 6-p-toluidinylnaphthalene-2-sulfonate (TNS), and l-dimethylaminonaphthalene-5-sulfonamidoethyltrimethylammonium (DASP). 

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