Pyridine carboxamides

Pyridine carboxamide [98-92-0] (nicotinamide) (1) and 3-pyridine carboxylic acid [59-67-6] (nicotinic acid) (2) have a rich history and their early significance stems not from their importance as a vitamin but rather as products derived from the oxidation of nicotine. In 1867, Huber prepared nicotinic acid from the potassium dichromate oxidation of nicotine. Many years later, Engler prepared nicotinamide. Workers at the turn of the twentieth century isolated nicotinic acid from several natural sources. In 1894, Su2uki isolated nicotinic acid from rice bran, and in 1912 Funk isolated the same substance from yeast (1). 

Pharmacology Niacinamide is synonymous with nicotinamide, 3-pyridine carboxamide, and nicotinic acid amide. Niacinamide is the amide of nicotinic acid (niacin, vitamin B3). Although nicotinic acid and nicotinamide function identically as vitamins, their pharmacologic effects differ. Nicotinamide does not have the hypolipidemic or vasodilating effects characteristic of niacin (nicotinic acid). 

RuClj(Hcbx)(cbx) (Hcbx=A-2 -chlorophenyl-2-pyridine-carboxamide). This red-brown material is made from the ligand and RuClj, and its X-ray crystal structure determined (Fig. 1.36). The system RuCl2(Hcbx)(cbx)/Oj/M( butyraldehyde/DCE epoxidised a number of cyclic alkenes efficiently at room temperatures (Table 3.1). Addition of the radical trap 2,6-di-ferf-butyl-4-methylphenol stopped epoxidation reactions altogether, suggesting that a mechanism involving radicals is involved [801],... 

Early publications on [VO(/3-diketonato)2] have been reviewed.355 More recently, complexes with benzoyl m-nitroacetanilide, benzoyl acetanilide545 and l,l -(l,3-phenylene)-bis(butane-1,3-dione546 have been synthesized. Other [VO(/S-dik)2] adducts have been isolated, for example [VO(acac)2] adducts with a series of pyridine N-oxides547 and several pyridine carboxamides, 48 and [VO(bzac)2] adducts with pyridine, methylamine, isoquinoline and 4-picoline.549 Equilibrium constants of 1 1 and 2 1 adducts of pyrazine with [VO(tfacac)2] have been determined (equation 38).550 In the 2 1 complex, the pyrazine bridge between two equatorial sites of adjacent vanadium atoms promotes a weak exchange interaction. The nitroxide radical 2,2,6,6-tetramethylpiperidinyl N-oxide also forms an adduct with [VO(hfacac)2] in which there is a strong interaction between the electrons on the metal and nitroxide.551... 

Ar-[( )-4-ethyl-2-[(Z)-hydroxyimino]-5-nitro-hexen-1 -yl]3-pyridine carboxamide (NOR4) 48... 

Carboxamides can be cathodically reduced to amines or alcohols, depending on the reaction conditions the reaction is carried out industrially. One example is the reduction of pyridine carboxamides at Reilly 543) ... 

Chloro-N-(2-chloro-4-methyl-3-pyridyl)-3-pyridine carboxamide... 

Orange Co3(pap)2(S04)2,12H20 is formed on reaction of iV-(2-pyridylmethylene-amino)-2-pyridine-carboxamide (papH) with CoS04 in aqueous ethanol in the presence of NaOH.182 Spectral data suggest that octahedral cobalt(n) is present and that the bonding is as shown in (37). 

The best result using aldehyde/oxygen was reported recently by Qi et al. [53] using novel Ru(HL)(L)C12 (HL is N-2 chlorophenyl-2-pyridine-carboxamide) complexes and isobutyraldehyde/oxygen for the epoxidation of cycbc alkenes. The turnover frequencies (TOFs) in this system were as high as 350 h 1 for cyclohexene, with a selectivity towards the epoxide of 87% (see Eq. 12). 

Substitution of hydrogen by phenyl in the amide group changes the product composition considerably electrolysis of TV-phenyl-4-phenyl-4-pyridine carboxamide in 1 M hydrochloric acid at —0.75 V gives a mixture of 4-pyridinemethanol and 4-anilinomethyl-pyridine ... 

The reduction of acyl hydrazines has been investigated very little. Polarography of 4-pyridine carboxylic acid hydrazide in acid and neutral solution shows that it is reduced in two, two-electrons steps [141]. The result of controlled potential electrolysis is cleavage of the N-N bond to form 4-pyridine-carboxamide, which then undergoes reduction to the aldehyde in the second step. Other hydrazides of heterocyclic carboxylic acids behave analogously. 

Although pyridine carboxamides are reduced to the carbinol at a lead cathode, in aqueous sulfuric acid the addition of titanium salts results in the aminomethylpyridine as the main product [453]. 

Niaprazine Nopron Sanofi- Synthelabo Piperazinyl- pyridine carboxamide 2 mg per kg... 

Casadio, S., Cousse, H., Mouzin, G. Nouvelles formes modulees de medicaments utiUsant les Ai-hydroxy alcoyl pyridine carboxamides comme vecteur. Fr. Pat.N°77.13478 (May 2, 1977, to P. Fabre S.A.) 1977. 

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