1-Benzyl-1,4-dihydronicotinamide

An intriguing use of a quaternary ammonium salt in a two-phase reaction is to be found with the regeneration of 1 -benzyl-1,4-dihydronicotinamide by sodium dithionite in a biomimetic reduction of thiones to thiols [12], The use of sodium dithionite in the presence of sodium carbonate for the 1,4-reduction of the pyri-dinium salts to 1,4-dihydropyridines is well established but, as both the dithionite and the pyridinium salts are soluble in water and the dihydropyridine and the thione are insoluble in the aqueous phase and totally soluble in the organic phase, it is difficult to identify the role of the quaternary ammonium salt in the reduction cycle. It is clear, however, that in the presence of benzyltriethylammonium chloride, the pyridine system is involved in as many as ten reduction cycles during the complete conversion of the thione into the thiol. In the absence of the catalyst, the thione is recovered quantitatively from the reaction mixture. As yet, the procedure does not appear to have any synthetic utility. 

The presence of a base is also essential for the efficient reductive dehalogenation of RX by 1-benzyl-1,4-dihydronicotinamide (BNAH) via photoinduced electron transfer [121,122], Since the one-electron oxidation potential of the singlet excited state of BNAH ( BNAH ) is —3.1 V (vs. SCE) [50], which is more negative than the one-electron reduction potential of benzyl bromide (PhCH2Br), photoinduced electron transfer from BNAH to PhCH2Br occurs efficiently with the diffusion-limited rate [122]. This fast process needs no base catalyst to accelerate the electron transfer rate further. However, the photoinduced electron transfer results in... 

The reaction of 1 -benzyl- 1,4-dihydronicotinamide (BNAH) with a series of 1,1-di-para-substituted-phenyl-2,2-dinitroethylenes in oxygen-saturated acetonitrile produced various amounts of the corresponding ethanes and diaryl ketones depending on the electronic structure of the substituent groups, thereby indicating a spectrum of behaviour intermediate between polar and SET mechanisms (Scheme ll).261... 

The catalytic activity of the immobilized flavin was determined using the oxidation of an NADH-analog, namely 1-benzyl-1,4-dihydronicotinamide (BNAH), as a model reaction (Figure 8). If a potential of +0.9 V is applied to the system, hydrogen peroxide, which is formed in the aerobic oxidation of BNAH by flavin, can be oxidized... 

The remainder of this section is devoted to cases in which an immobilized oxidizing reagent can be regenerated by the action of a simple oxidant, such as a peroxide or O2. For instance, the flavin 10-ethyl-isoalloxazine was immobilized on organic polymers and used in the air oxidation of 1 -benzyl-1, 4-dihydronicotinamide (395). However, peracids, dioxiranes, and nitroxyl radicals are of much more synthetic importance. 

Shiragami, T. Fukami, S. Pac, C. Yanagida, S. Semiconductor photocatalysis Quantised CdS-catalysed photoformation of 1 -benzyl- 1,4-dihydronicotinamide (BNAH) from 1-benzylnicotinamide (BNA+), 7. Chem. Soc., Faraday Trans. 1993, 89, 1857. 

In addition to described heterogeneous systems a homogeneous photocatalytic C02 reduction was tested using heteroleptic rhenium complexes [99, 100] and supramolecular ruthenium and rhenium bi- and tetranuclear complexes their excited states were quenched by 1-benzyl-1,4-dihydronicotinamide (BNAH) and C02 was reduced by the electron donor intermediate species [101]. 

The unusual variant (18) is formed by the photodimerization of 1-benzyl-1,4-dihydronicotinamide <83TL5399>, neither the head-to-head isomer of compound (18) nor the 5,5 -linked dimer was observed. Further investigation appears desirable to examine the mechanism and scope of this reaction. 

DIOP]Rh(solvent)Cl (in 60% optical yield28 compared with only 6% optical yield with 1 -benzyl-1,4-dihydronicotinamide in the presence of magnesium perchlorate in the simple asymmetric reduction29). 

Biomimetic-type reduction of preformed eniminium salts with the Hantzsch ester or 1-benzyl-1,4-dihydronicotinamide results in stereospecific formation of cis ring fused ketones23 (Scheme 14). 

Pac and his coworkers reported the Ru(bpy)3 -sensitized photoreduction of electron deficient alkenes by 1-benzyl-1,4-dihydronicotinamide (BNAH) in methanol [116-118]. In this photoreaction, BNAH is first oxidized by Ru(bpy)3 to give BNAH and Ru(bpy)3. The radical anions of the electron-deficient alkenes, which are generated by photoinduced electron transfer from Ru(bpy)3 to the alkene, are then protonated to give the reduction products (Scheme 35). 

The photoreactions of some amines with Co(acac), have been described these lead to a novel type of coupling process between the amines and the P-diketone which occurs by an electron transfer process. Photoreduction of Co(acac)3 by 1-benzyl-1,4-dihydronicotinamide is promoted in SDS micelles. ... 

The effects of Mg + on hydride transfer reactions from a typical NADH model compound, 1-benzyl-1,4-dihydronicotinamide (BNAH), to substrates are complex... 

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