Picolinamide

The picolinamide is prepared in 95% yield from picolinic acid/DCC and an amino acid, and is hydrolyzed in 75% yield by aqueous Cu(OAc)2. ... 

Fueled by the success of the Mn (salen) catalysts, new forays have been launched into the realm of hybrid catalyst systems. For example, the Mn-picolinamide-salicylidene complexes (i.e., 13) represent novel oxidation-resistant catalysts which exhibit higher turnover rates than the corresponding Jacobsen-type catalysts. These hybrids are particularly well-suited to the low-cost-but relatively aggressive-oxidant systems, such as bleach. In fact, the epoxidation of trans-P-methylstyrene (14) in the presence of 5 mol% of catalyst 13 and an excess of sodium hypochlorite proceeds with an ee of 53%. Understanding of the mechanistic aspects of these catalysts is complicated by their lack of C2 symmetry. For example, it is not yet clear whether the 5-membered or 6-membered metallocycle plays the decisive role in enantioselectivity however, in any event, the active form is believed to be a manganese 0x0 complex <96TL2725>. 

A variety of gold(III) complexes of carboxamido substituted heterocyclic ligands are obtained by reaction of [AuCh] with the appropriate ligands, these include [Au (N,N )Cl2j (HN,N =picolinamide) (IS) [70], [Au(N,N, N")Cl]Cl [N,N H,N" = N-(8-quinolyl)pyridine-2-carboxamide (16), N-(8-quinolyl)glycine-2-carboxamide (17) or N-(8-quinolyl)-L-alanine-2-carboxamide (18)] [71] (Figure 2.11). 

To test this hypothesis, the picolinamide 22 was prepared using in situ activated picolinic acid (Scheme 8.12). The in situ activation of picohnic acid was used because picolinyl chloride (available commercially as the HC1 salt) is relatively expensive. The coupling reaction was not straightforward, and the best results were obtained by adding 1.4equiv of thionyl chloride to a solution of 1.4equiv of picolinic acid in acetonitrile, followed by addition of triethylamine. As soon as the addition of triethylamine was complete, aniline 5 was introduced immediately because the activated picolinic acid was unstable in the presence of triethylamine. 

Picolinamide 22 could be isolated in 87% yield by crystallization from aqueous i-PrOH, which also resulted in an ee upgrade from 92% to 99.3%. Deprotection of the N-Boc group was performed by dissolving 22 in 5 M aqueous HC1. It was found that the subsequent N-acetylation of the revealed amine could be performed in the same pot under Schotten-Baumann conditions by simply adding 10M aqueous NaOH and Ac20. After extraction with CH2C12, the organic phase was concentrated and used in the nitration step without any further purification. 

Complexes of picolinamide with lanthanide perchlorates, nitrates, and isothiocyanates have been isolated by Condorelli et al. (59). All these complexes show changes in the stoichiometry on going from La(III) to Lu(III). The ligand acts as bi-dentate with the oxygen of the amide group as well as the heterocyclic nitrogen coordinating to the metal (Structure I). While the anions in the perchlorate complexes are not coordinated to lanthanide ions, those in the nitrate and isothiocyanate complexes are coordinated. 

Phthalic anhydride, see Benzo[a]anthracene, Bis(2-ethylhexyl) phthalate Carbaryl, Dichlone. Diethyl phthalate, Naphthalene Phthalide, see Naphthalene Phthalimide, see Phorate Picolinamide, see Dignat o-Picolinic acid, see Dignat Picric acid, see Parathion Pinacol, see Acetone Pinonaldehyde, see g-Pinene Polychlorinated dibenzofurans, see PCB-1242,... 

The first fully aromatic 2-azaquinolizinium salts were prepared by Krohnke et al. (64CB3566), who examined three approaches to the l-hydroxy-3-phenyI-2-azaquinoIizinium ion (262 Scheme 130). The first involved the reaction of picolinamide (261) with phenacyl bromide which produced (262) in unspecified yield. Most effective was refluxing 2-cyanopyridine (263) in moist acetonitrile with phenacyl bromide. Finally, it was shown that 2-ethoxycarbonyl-l-phenacylpyridinium ion (265) could serve as a starting material if ammonium acetate were present in the solvent. 

Copper(JI) has been found to inhibit the hydrolysis of glycylglycine in basic solution (pH> 11).127 Conley and Martin128 have also found that, at pH values in excess of 11, copper(II) inhibits the hydrolysis of glycinamide due to amide hydrogen ionization. Similar results were obtained with picolinamide, and a bis-picolinamide complex of nickel(II) containing deprotonated amide groups was isolated.128... 

Baaden, M., Berny, F., Madic, C., Schurhammer, R., Wipff, G. 2003. Theoretical studies on lanthanide cation extraction by picolinamides Ligand-cation interactions and interfacial behavior. Solvent Extr. IonExch. 21 (2) 199-220. 

Cordier, P.Y., Condamines, N. 1993. De nouvelles Molecules pour la Separation des Actinides Les Picolinamides. GECOM-CONCOORD 93, La-Lomde-Les-Maures, France, May. 

Cordier, P.-Y. 1996. Separation of actinides(III) and lanthanides(BI) by liquid-liquid extraction with the novel molecules The picolinamides. Thesis. Blaise Pascal Clermont-Ferrand University. 

Several spectroscopic techniques, namely, Ultraviolet-Visible Spectroscopy (UV-Vis), Infrared (IR), Nuclear Magnetic Resonance (NMR), etc., have been used for understanding the mechanism of solvent-extraction processes and identification of extracted species. Berthon et al. reviewed the use of NMR techniques in solvent-extraction studies for monoamides, malonamides, picolinamides, and TBP (116, 117). NMR spectroscopy was used as a tool to identify the structural parameters that control selectivity and efficiency of extraction of metal ions. 13C NMR relaxation-time data were used to determine the distances between the carbon atoms of the monoamide ligands and the actinides centers. The II, 2H, and 13C NMR spectra analysis of the solvent organic phases indicated malonamide dimer formation at low concentrations. However, at higher ligand concentrations, micelle formation was observed. NMR studies were also used to understand nitric acid extraction mechanisms. Before obtaining conformational information from 13C relaxation times, the stoichiometries of the... 

Picolinamide derivatives show interesting Am/Eu selectivity, but an efficiency that is highly pH-dependent. 

Distribution Ratios3 and Selectivity for the Extraction of Am and Eu from Aqueous Solutions 10 3 M HN03 into a NPHE/3 10 3 M [Bromocosan] Solution of Picolinamide Calixarenes... 

Under the same conditions, in contrast to what is observed for calix[4]arene-bearing CMPO moieties, with CPil2, distribution ratios of lanthanides increase from the lightest lanthanide, lanthanum, to europium. Americium can be easily separated from the lightest lanthanides (separation factor DAm/La > 20, DAm/Ce =15, /lAlll,Nd = 10, UAi /si = 7.5, DAm/Eu = 6), which are the most abundant lanthanides in fission-product solution. Cavitands bearing picolinamide (Cv5) or thiopicolin-amide (Cv6) residues seems much less selective than their calixarene counterparts, giving SAm/Eu < 2.18... 

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