Synthesis of Some Substituted Dimethyl and Diethyl 4-(Phenylethynyl)-2,6-pyridinedicarboxylates.

Takalo, Harri; Kankare, Jouko; Hänninen, Elina; Vogt, Carmen; Enzell, Curt R.; Berg, Jan-Eric; Bartók, Mihály; Pelczer, István; Dombi, György

doi:10.3891/acta.chem.scand.42b-0448

Cited by 31 publications

(22 citation statements)

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“…Slow removal of one Me 3 Si-alkyne protecting group in (À)-(R)- 40 [11b] with borax in aqueous THF afforded (À)-(R)-41 in 31% yield, together with unreacted starting material (67%), which was resubmitted to the deprotection in an iterative fashion, ultimately allowing good overall conversion. For the subsequent cross-coupling, diethyltriazenyl-benzoate 42 was prepared starting from 2-amino-5-iodobenzoic acid via the corresponding methyl ester [31], according to published procedures [32]. Coupling of (À)-(R)-41 to 42 under Sonogashira conditions [19] provided (À)-(R)-43 in 76% yield, together with the diacetylene by-product (À)-(R,R)-44 (16%) resulting from competing oxidative dimerization of (À)-(R)-41 (under Glaser-Hay conditions, (À)-(R)-41 can be quantitatively converted into (À)-(R,R)-44).…”

Section: Synthetic Receptors For Monosaccharides and Disaccharides mentioning

confidence: 99%

“…Furthermore, sandwiching the bound carbohydrate guest between aromatic rings located atop of and below the H-bonding cavity should greatly increase the number of hostÀguest dispersion and CH´´´p interactions, as well as enhance favorable hydrophobic desolvation processes, thereby enabling stable carbohydrate complexation in aqueous solution [5]. , methyl 2-amino-5-iodobenzoate [31], 61 [44], methyl 2,5-diiodobenzoate [51], [PdCl 2 (dppf)]´CH 2 Cl 2 [52], and CuCl [53] were synthesized according to literature procedures. The octyl glycosides 63 ± 65, 67 [54], and 68 [55] were prepared according to known protocols [56].…”

Section: Synthetic Receptors For Monosaccharides and Disaccharides mentioning

confidence: 99%

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Optically Active Cyclophane Receptors for Mono- and Disaccharides: The Role of Bidentate Ionic Hydrogen Bonding in Carbohydrate Recognition

Droz¹,

Neidlein²,

Anderson³

et al. 2001

HCA

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A new family of optically active cyclophane receptors for the complexation of mono-and disaccharides in competitive protic solvent mixtures is described. Macrocycles (À)-(R,R,R,R)-1 ± 4 feature preorganized binding cavities formed by four 1,1'-binaphthalene-2,2'-diyl phosphate moieties bridged in the 3,3'-positions by acetylenic or phenylacetylenic spacers. The four phosphodiester groups converge towards the binding cavity and provide efficient bidentate ionic H-bond acceptor sites (Fig. 2). Benzyloxy groups in the 7,7'-positions of the 1,1'-binaphthalene moieties ensure solubility of the nanometer-sized receptors and prevent undesirable aggregation. The construction of the macrocyclic framework of the four cyclophanes takes advantage of Pd 0 -catalyzed arylÐacetylene cross-coupling by the Sonogashira protocol, and oxidative acetylenic homo-coupling methodology (Schemes 2 and 8 ± 10). Several cleft-type receptors featuring one 1,1'-binaphthalene-2,2'-diyl phosphate moiety were also prepared (Schemes 1, 6, and 7). An undesired side reaction encountered during the synthesis of the target compounds was the formation of naptho[b]furan rings from 3-ethynylnaphthalene-2-ol derivatives, proceeding via 5-endo-dig cyclization (Schemes 3 ± 5). Computer-assisted molecular modeling indicated that the macrocycles prefer nonplanar puckered, cyclobutane-type conformations (Figs. 7 and 8). According to these calculations, receptor (À)-(R,R,R,R)-1 has, on average, a square binding site, which is complementary in size to one monosaccharide. The three other cyclophanes (À)-(R,R,R,R)-2 ± 4 feature, on average, wider rectangular cavities, providing a good fit to one disaccharide, while being too large for the complexation of one monosaccharide. This substrate selectivity was fully confirmed in 1 H-NMR binding titrations. The chiroptical properties of the cyclophanes and their nonmacrocyclic precursors were investigated by circular dichroism (CD) spectroscopy. The CD spectra of the acyclic precursors showed a large dependence from the number of 1,1'-binaphthalene moieties (Fig. 9), and those of the cyclophanes were remarkably influenced by the nature of the functional groups lining the macrocyclic cavity (Fig. 11). Profound differences were also observed between the CD spectra of linear and macrocyclic tetrakis(1,1'-binaphthalene) scaffolds, which feature very different molecular shapes (Fig. 10). In 1 H-NMR binding titrations with mono-and disaccharides (Fig. 13), concentration ranges were chosen to favor 1 : 1 hostÀguest binding. This stoichiometry was experimentally established by the curve-fitting analysis of the titration data and by Job plots. The titration data demonstrate conclusively that the strength of carbohydrate recognition is enhanced with an increasing number of bidentate ionic hostÀguest H-bonds (Table 1) in the complex formed. As a result of the formation of these highly stable H-bonds, carbohydrate complexation in competitive protic solvent mixtures becomes more favorable. Thus, cleft-type receptors (À)-(R)-7 and (À...

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Section: Synthetic Receptors For Monosaccharides and Disaccharides mentioning

confidence: 99%

Section: Synthetic Receptors For Monosaccharides and Disaccharides mentioning

confidence: 99%

Optically Active Cyclophane Receptors for Mono- and Disaccharides: The Role of Bidentate Ionic Hydrogen Bonding in Carbohydrate Recognition

Droz¹,

Neidlein²,

Anderson³

et al. 2001

HCA

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“…These intermediates can be prepared by Sonogashira coupling reactions of the appropriate iodo dialkylamino benzenes with either (trimethylsilyl)acetylene or 2-methyl-3-butyn-2-ol followed by a subsequent cleavage of the protection group in two steps 29,30 or a Wittig-type one pot synthesis starting from the corresponding aldehydes. 31 Although we have previously proven that both methods are suitable to obtain the terminal aryl acetylenes in high yields, 21 the former method was chosen because various alkyl chains could be easily realized for alternative PIs in further studies, while the counterpart aldehyde compounds are not always commercially available.…”

Section: Synthesismentioning

confidence: 99%

Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

Siklos

Pucher

et al. 2011

J. Polym. Sci. A Polym. Chem.

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Several novel aromatic ketone-based two-photon initiators containing triple bonds and dialkylamino groups were synthesized and the structure-activity relationships were evaluated. Branched alkyl chains were used at the terminal donor groups to improve the solubility in the multifunctional monomers. Because of the long conjugation length and good coplanarity, the evaluated initiators showed large two-photon cross section values, while their fluorescence lifetimes and quantum yields strongly depend on the solvent polarity. All novel initiators exhibited high activity in terms of two-photon-induced microfabrication. This is especially true for fluorenone-based derivatives, which displayed much broader processing windows than well-known highly active initiators from the literature and commercially available initiators. While the new photoinitiators gave high reactivity in two-photoninduced photopolymerization at concentration as low as 0.1% wt, these compounds are surprisingly stable under one photon condition and nearly no photo initiation activity was found in classical photo DSC experiment.

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“…The halogen functions at C(4) of the pyridine were first substituted by (4-aminophenyl)ethyne moieties (Scheme 1) according to a modification of Heck×s coupling reaction [22] reported by Sonogashira et al [23]. (4-Aminophenyl)ethyne itself was synthesized via a literature procedure [24] in a somewhat better yield (54 instead of 43%), similar to the yield reported by Mongin and Gossauer (57%) [25]. Our choice of this method over the more efficient one proposed by Lavastre et al (71%) [26] was dictated by the milder reaction conditions and lower cost of the starting materials.…”

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confidence: 99%

Self-Assembled Triple-Stranded Lanthanide Dimetallic Helicates with a Ditopic Ligand Derived from Bis(benzimidazole)pyridine and Featuring an (4-Isothiocyanatophenyl)ethynyl Substituent

Tripier¹,

Hollenstein²,

Elhabiri³

et al. 2002

HCA

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Bis(2-{6-(diethylcarbamoyl)-4-[(4-isothiocyanatophenyl)ethynyl]pyridin-2'-yl}-1-ethylbenzimidazol-5-yl)-methane (L G ) reacts with trivalent lanthanide ions in acetonitrile to yield triple-stranded dimetallic helicates [Ln 2 (L G ) 3 ] 6 . 1 H-NMR Data point to the helicates being the only species formed under stoichiometric conditions and having a time-averaged D 3 symmetry on the NMR time scale. The photophysical properties of L G and its helicates are discussed with respect to the closely related ligands L B , L E , and their complexes, two ligands devoid of the isothiocyanatophenylethynyl substituent. The quantum yield of the ligand fluorescence is three times smaller compared to L E , while that of the Eu III -centered luminescence (1.1%) is three times larger. On the other hand, the luminescence of Tb III is not sensitized by L G . This is explained in terms of energy differences between the singlet and triplet states on one hand, and between the 0-phonon transition of the triplet state and the excited metal ion states on the other. This work demonstrates that bulky substituents in the 4-position of the pyridine ring do not prevent the formation of triple-stranded helicates, opening the way for luminescent probes that can easily be coupled to biological materials.Introduction. ± Supramolecular functional architectures containing lanthanide ions receive a sustained interest, especially in the field of medicine, because the optical and magnetic properties arising from the shielded 4f electronic configurations are easily traceable, therefore, providing suitable diagnostic [1] [2], therapeutic [3] [4], or analytical tools [5] [6]. One challenge associated with the development of such molecular edifices lies in the accurate control of the Ln III inner coordination sphere in order to reach large thermodynamic stability and kinetic inertness without altering the specific properties of the metal ion. In the particular case of photophysical properties, additional features have to be incorporated in the receptor in order to achieve efficient sensitization of the luminescent lanthanide ions [7]. In recent years, we have focused part of our research efforts on the design of segmental ligands featuring aromatic tridentate and/or bidentate coordination units and coded for the self-assembly of 4f-4f [8] or 4f-3d [9] [10] dimetallic helicates. We have shown that the coordination sphere of the Ln III ions can be controlled by semirigid aromatic tridentate ligands such as bis(benzimidazole)pyridines [11] [12]. The covalent connection of two such units leads, for example, to the formation of ditopic ligand L A (Scheme 1), forming stable dimetallic helicates [Ln 2 (L A ) 3 ] 6 in MeCN in which the ligand strands are wrapped around two 9-coordinate Ln III ions with tricapped trigonal prismatic coordination geometry [13] [14]. The self-assembly process results in the formation of protective

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Synthesis of Some Substituted Dimethyl and Diethyl 4-(Phenylethynyl)-2,6-pyridinedicarboxylates.

Cited by 31 publications

References 0 publications

Optically Active Cyclophane Receptors for Mono- and Disaccharides: The Role of Bidentate Ionic Hydrogen Bonding in Carbohydrate Recognition

Optically Active Cyclophane Receptors for Mono- and Disaccharides: The Role of Bidentate Ionic Hydrogen Bonding in Carbohydrate Recognition

Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

Self-Assembled Triple-Stranded Lanthanide Dimetallic Helicates with a Ditopic Ligand Derived from Bis(benzimidazole)pyridine and Featuring an (4-Isothiocyanatophenyl)ethynyl Substituent

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