Nicotinic acid, analogues

The coordination modes found in Ni11 complexes with 2-(diphenylphosphino)nicotinic acid and its methyl ester and 2-(diphenylphosphino)benzoic acid and its methyl ester are surprising.696 The complex with the benzoic acid derivative shows the expected P,0 coordination with a six-membered chelate ring (252), while the nicotinic acid analogue forms a four-membered chelate ring with P,N binding (251). 

At the beginning, we used NA as the inducer to the culture medium. However, the activity was not induced to achieve a high level production of 6-CHP. So we screened various nicotinic acid analogues such as 6-chloronicotinic acid, 6-fluoronicotinic acid, 2-chloronicotinic acid, 2-hydroxynicotinic acid, 2,6-dihydroxypyridine, 2,3-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid,... 

The kinetics of reaction of DABCO (7.66) and nicotinic acid (7.67 R = COOH) with the aminochlorotriazine dye Cl Reactive Red 3 (7.2) were studied under neutral conditions at temperatures in the range 100-130 °C. Quaternisation by DABCO was much more rapid than by nicotinic acid under these conditions. Neutral exhaust dyeing tests at 130 °C using the bis(aminochlorotriazine) analogue Cl Reactive Red 120 (7.48 X = Cl) with the two catalysts confirmed these trends, in that the degree of fixation was greatly increased by DABCO but nicotinic acid showed no appreciable catalytic effect [60]. This difference may be attributable to steric strain of the C-N+ bond in the quaternised triazine structure by the non-planar DABCO substituent. 

Formation of the 2-aminoadenine analogue of NAD by H.Ep.-2 cells in culture has been demonstrated, and it appears quite likely that dinucleotides containing 2-aminoadenine and nicotinic acid or nicotinamide can be formed in living... 

For every biologically active carboxylic acid, there is a bioisosteric compound in which the carboxyl group is replaced by a tetrazol-5-yl moiety. The tetrazole compounds are degraded biologically more slowly than carboxylic acids. For instance, the tetrazole analogue 11 of nicotinic acid reduces the fatty acid and cholesterol levels in blood. 

This relates particularly to the incorporation by living organisms of fluoroacetic acid in the place of acetic acid or of 5-fluoro-nicotinic acid and 5-fluoro-uracil as antimetabolites (see Chapter 17, the section on halogens). This fraudulent incorporation leads to lethal syntheses. This is generally not the case with the corresponding chlorinated, brominated or iodinated analogues. 

Nicotine.—Nicotine (33) is assembled in Nicotiana species from nicotinic acid (31) and N-methyl-A -pyrroline (32). Administration to Nicotiana plants of 5-fluoronicotinic acid and derivatives of (32) methylated at C-2 and C-3 has resulted in the formation in vivo of unnatural nicotine analogues.In contrast, 4-methylnicotinic acid has been found not to be transformed in vivo into 4-methylnicotine, presumably because this particular methyl group interferes sterically with the appropriate enzyme reactions involved in nicotine biosynthesis. ... 

CD-bonded stationary phases are suitable for the separation of positional, geometric and optical isomers, derivatives of dansyl racemic amino acids, analogues of nicotine and nicotine analogs, arbitrates and derivatives of benzodiazepin as well as organic nitrates, imidazol derivatives, etc. Table 8.2 shows that some enantioselective stationary phases are based on modified CDs [32,33]. The first CD derivatives used as a chiral stationary phase in HPLC were hydroxypropyl, acetylated and carbamoylated /3-CD, which demonstrated better selectivity behaviors than native /3-CD. The most common commercial species of CD derivatives include water-soluble methylated CD (2,6-di-0-methyl-j8-CD) and HP-j6-CD, then acetylated CD, carboxymethylated CD, naphthyl ethyl carbamate-j8-CD,... 

For heterocyclic analogues, e.g. nicotinic acid (7-7) and its isomers, see Lumme (1957). 

Figure 12.8 Structures of nicotinic acid and its synthetic analogue acipimox.

A compound prepared and first described as nicotinium dichromate (NDC) by Palomo et al.,379 was later shown by X-ray-crystal analysis380 to be a betainic mixed anhydride of nicotinic and chromic acid (NACAA). Because of its unique structure, it deserves a close scrutiny of its oxidative properties.381 Replacement of the chloride anion in the quaternary ammonium resin, Dowex 1-X8, for the dichromate anion, leads to a polymer supported dichromate, which is able to make selective benzylic oxidations.382 Finally, poly[vinyl(pyridinium dichromate)] (PVPDC), a polymeric analogue of PDC, must be mentioned whose use in the oxidation of alcohols allows for a very easy work-up.383... 

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