Dicarboxamide pyridine

The Pd-catalyzed carbonylation of 2,6-dibromopyridine in the presence of 2-pyridylamine gave N,lV -di(2-pyridyl)pyridine-2,6-dicarboxamide under relatively high pressure and prolonged reaction time [156]. Partial aminocarbonylation of 2,6-dibromopyridine was more cumbersome—only 55% of the monocarboxamide 195 was isolated in a shorter reaction time accompanied by the corresponding 2,6-dicarboxamide in 32% yield. 

Figure 11.31 Conformational equilibria of pyridine-2,6-dicarboxamides, as calculated using density functional theory (B3LYP/6-311-L G //B3LYP/6-31G ), favors a syn-syn conformation.

Benzylpropylperoxy- A, A-bis[2-(2-pyridyl)ethyl]pyridine-2,6-dicarboxamide cobalt(lll) (EEEBOH) 1.488 1.432 161.6 130... 

A partially rigid foldamer system was recently reported by Parquette et al. [79]. The oligomers were derived from alternating sequences of pyridine-2,6-dicarboxamides and raeta-(phenylazo)azobenzenes. The helical conformations were revealed by crystal structures. In solution, the folded conformations and their corresponding dynamics were probed by NMR. 

The first metal-ligand alternative base pair to be incorporated in DNA duplexes was of [3 -f-1] type and was reported by Meggers et al. in 2000 (96). This pair was based on tridentate pyridine-2,6-dicarboxylate (Dipic) and monodentate pyridine (py) ligands, which were introduced in complementary positions in the middle of a DNA duplex (Entry 14, Table V). The same group reported the incorporation in DNA duplexes of three other tridentate ligands that bear structural similarity to Dipic, namely, pyridine-2,6-dicarboxamide (Di-pam) (Entry 15, Table V) (120), pyridine-2,6-(N-methyl-)dicarboxamide (Me-Dipam) (120), and 2,6-bis(ethylthiomethyl)pyridine (SPy) (Entry 16, Table V) (106). In the absence of a metal ion, incorporation in DNA duplexes of any of the four tridentate ligands opposite a pyridine had a destabilization effect similar to that of a mismatch or completely prevented the formation of a duplex. 

Chmielewski and Jurczak have reported a series of extended tetra-amide macrocycles containing two pyridine-2,6-dicarboxamide caps finked via short aliphatic chains. The macrocycles possess a well-defined cavity with all the amide groups directed inwards [19,20]. 

More recently the same authors have studied the anion binding ability of similar macrocyclic systems based on isophthalamides [21]. The isophthala-mide moieties were introduced as previous studies have shown isophthala-mide derivatives bind anions more strongly than the analogous pyridine-2,6-dicarboxamides [22],... 

Stability constants were obtained for receptors 13a, 13b and 13c using analogous conditions to those employed for receptors 12a, 12b and 12c. As with the pyridine-2,6-dicarboxamide macrocydes, the stability constants for the isophthalamide macrocydes appear to be influenced by the size and flexi-bihty of the system with the higher constants observed in the 20-membered receptor 13a with notable decreases in the assodation constants with the 22-and 24-membered receptors 13b and 13c. The greatest decreases where observed in the stability constants obtained with the carboxylate anions. In the case of acetate the constants decreased from 3130 M for 13a to 552 M and 205 M for 13b and 13c, respedively. hi the case of benzoate a constant of 601 M was calculated for 13a decreasing to 302 M and 82 M for 13b and 13c, respectively. Unexpectedly lower binding constants were obtained for the isophthalamide macrocydes (13a-13c) compared to the pyridine-... 

Recently, Sessler and co-workers have appended the 2-aminopyrroles subunit onto a pyridine-2,6-dicarboxamide spacer group to afford two acychc receptors (compoimds 40a and 40b) [53]. 

Recently Katayev, Sessler and co-workers have further developed the hybrid macrocycle systems by replacing the pyridine-2,6-dicarboxamide moieties used in receptors 43 and 44 with bipyrrole and dipyrromethane subunits... 

Recently, Gale and co-workers have synthesized simple clefts with indole subunits appended to isophthalamide and pyridine-2,6-dicarboxamide spacers and described their anion-binding properties [76]. 

Another involves a square featuring OsOq units as two diagonal comers and pyridine-2,6-dicarboxamides as the other corners (6). This assembly selectively binds appropriately sized amides via multiple hydrogen-bonding interactions. 

Figure 3.14 Metallation of Wright s pyridine-2,6-dicarboxamide ligand appended with pyridine groups (a) and formation of a ruthenium nitrosyl via proton transfer and water elimination (b).

Cu(BHPPDAH) H20-catalyzed one-pot synthesis of benzimidazoles was first reported by Sharghi et al. (2008). The catalyst was prepared from Cu(OAc)2 and A/,A-bis(2-hydroxyphenyl)-pyridine-2,6-dicarboxamide (BHPPDAH) (Scheme 4.43). Facilitated by the recyclable Cu(II) complex, various o-phenylenediamines smoothly cyclized with aromatic aldehydes to give benzimidazoles at room temperature under air atmosphere (Scheme 4.44). 

Twelve additional Co(lll)-alkylperoxo complexes have been synthesized, including those of the hgand A/, A -bis[2-(l-pyrazolyl)-ethyl]-pyridine-2,6-dicarboxamide (PyPz2PH2) (Figure 60), with various primary, secondary, and tertiary R groups. ... 

CD derivatives can change their conformations in different media, and these conformation conversions can greatly affect their molecular recognition abiUties. For example, pyridine-2,6-dicarboxamide-bridged bis(jS-CD) 6 displays quite different circular dichroism spectra at different pH values [12], which indicates... 

In addition to organometaUic dendrimers for asymmetric catalysis, a number of dendritic organocatalysts have been developed and successfully applied in different asymmetric reactions in the absence of any metal [63]. In 2009, Parquette and coworkers [64] reported a new kind of folded pyridine-2,6-dicarboxamide dendrons (36) for direct aldol reaction. These dendritic prolinamide catalysts were tested for the aldol reactions of various acycUc and cydic ketones with 4-nitrobenzaldehyde (Figure 4.33). Remarkable dendritic effects on both the enantioselectivity and... 

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