- Water-soluble chiral polyisocyanides showing thermoresponsive behavior
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To afford chiral polyisocyanides with thermoresponsiveness may open new gates to enhance their functionality and to broaden their applications. Herein, we report the synthesis of a series of novel polyisocyanides carrying oligoethylene glycols (OEGs) modified dipeptides as the pendent groups. These polyisocyanides not only show different chiroptical properties but also possess characteristic thermoresponsive behavior. The corresponding monomers carrying different OEG units in the periphery are water-soluble, thus allowing their polymerization feasible in aqueous medium with NiCl2 as the catalyst. For comparison, polyisocyanides were also prepared in organic solvents, such as dichloromethane and tetrahydrofuran. The effects of solvent and polymerization temperature as well as chemical structures of the pendants on the chiroptical properties of the resulting polymers were examined. The characteristic thermoresponsive behavior of these chiral polymers was investigated by 1H NMR spectroscopy and turbidity measurements using UV/vis spectroscopy. The thermally induced aggregation processes were also followed by dynamic light scattering. It was found that the phase transition temperatures of these polymers were significantly influenced not only by the overall hydrophilicity but also by their secondary structures.
- Hu, Guixia,Li, Wen,Hu, Yulong,Xu, Anqiu,Yan, Jiatao,Liu, Lianxiao,Zhang, Xiacong,Liu, Kun,Zhang, Afang
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- An aryne-based three-component access to α-aroylamino amides
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Aryne chemistry has recently received widespread attention and isocyanides have been reported as efficient nucleophilic partners in a set of multicomponent transformations. In this study, we demonstrate that tertiary α-monosubstituted α-isocyanoacetamides are efficaciously coupled with water and benzyne to offer a direct and metal-free access to densely functionalized α-benzoylamino amides, without competing with the intramolecular cyclization to 5-aminooxazoles. Despite the formation of the aryl anion as a key intermediate, the reaction displays a stereoconservative course, allowing for the preparation of enantiomerically pure α-benzoylamino amides. Finally, the synthetic utility of the reported MCR was exemplified by the preparation of proglumide, a cholecystokinin antagonist.
- Serafini, Marta,Griglio, Alessia,Viarengo, Sara,Aprile, Silvio,Pirali, Tracey
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- Enantioselective Rh-catalyzed hydrogenation of N-formyl dehydroamino esters with monodentate phosphoramidite ligands
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Enantioselectivities up to >99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using monodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cyclohexanone. A highly convenient multigram scale one step synthesis of methyl 2-(formamido)acrylate was developed. This compound was used in the synthesis of methyl 2-(formamido)cinnamate via a solvent free Heck reaction. Moreover, full conversion and >99% ee were obtained in 1 h in the hydrogenation of methyl 2-(formamido)acrylate with 0.2 mol% catalyst and 2 bar hydrogen pressure. The versatility of the formyl protection was established by its removal under mild conditions.
- Panella, Lavinia,Aleixandre, Alicia Marco,Kruidhof, Gerlof J.,Robertus, Jort,Feringa, Ben L.,De Vries, Johannes G.,Minnaard, Adriaan J.
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- Formyloxyacetoxyphenylmethane as an N-Formylating Reagent for Amines, Amino Acids, and Peptides
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Formyloxyacetoxyphenylmethane is a stable, water-tolerant, N-formylating reagent for primary and secondary amines that can be used under solvent-free conditions at room temperature to prepare a range of N-formamides, N-formylanilines, N-formyl-α-amino acids, N-formylpeptides, and an isocyanide.
- Chapman, Robert S. L.,Lawrence, Ruth,Williams, Jonathan M. J.,Bull, Steven D.
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supporting information
p. 4908 - 4911
(2017/09/23)
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- Helical Polyisocyanopeptides as Lyotropic Liquid Crystals for Measuring Residual Dipolar Couplings
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Residual dipolar couplings (RDC) emerged to be an important structural parameter for organic and biomolecules. Herein, a new helical polyisocyanopeptide (l,l-PIAF-OBn) that forms lyotropic liquid crystals (LLC) in CDCl3 is proposed as a novel weakly orienting medium for acquiring residual dipolar couplings (RDCs) of organic molecules. We demonstrate its application for the structural elucidation of strychnine and triptolide.
- Li, Gao-Wei,Cao, Jiang-Ming,Zong, Wen,Hu, Li,Hu, Mao-Lin,Lei, Xinxiang,Sun, Han,Tan, Ren Xiang
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supporting information
p. 7653 - 7656
(2017/06/06)
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- Enantioselective Synthesis of Quaternary Δ4- and Δ5-Dehydroprolines Based on a Two-Step Formal [3+2] Cycloaddition of α-Aryl and α-Alkyl Isocyano(thio)acetates with Vinyl Ketones
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A divergent synthesis of optically active quaternary Δ4- and Δ5-dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α-substituted isocyano(thio)acetates to vinyl ketones that is general for both α-aryl and α-alkyl isocyano(thio)acetates. The new tetrasubstituted C?N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H???H interatomic distance in the solid state.
- Odriozola, Amaiur,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 12758 - 12762
(2017/09/25)
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- 2,3-DIHYDROIMIDAZOL[1,2-C]PYRIMIDIN-5(1H)-ONE BASED LIPOPROTEIN-ASSOCIATED PHOSPHOLIPASE A2 (LP-PLA2) INHIBITORS
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The present invention relates to novel compounds that inhibit Lp-PLA2 activity, processes for their preparation, to compositions containing them and to their use in the treatment of diseases associated with the activity of Lp-PLA2, for example atherosclerosis, Alzheimer's disease.
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Page/Page column 31-32
(2014/08/07)
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- COMPOUNDS
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The present invention relates to novel compounds that inhibit Lp-PLA2 activity, processes for their preparation, to compositions containing them and to their use in the treatment of diseases associated with the activity of Lp-PLA2, for example atherosclerosis, Alzheimer's disease.
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Paragraph 0203; 0204; 0205
(2014/08/07)
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- Expression of binding energy on an antibody reaction coordinate
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In this paper, we report the investigation of how the catalytic antibody 17E8 uses remote binding energy along the catalyzed hydrolytic reaction coordinate. With the use of alternative substrate analogues, we find that 17E8 can use free energy from binding interactions between the substrate side chain and antibody recognition pocket to equally stabilize the transition state and the Michaelis complex. In these cases, the interactions are not used to increase k(cat). We have also identified substrates for which the interactions are used to preferentially stabilize the transition state over the Michaelis complex. In these cases, the interactions are used to increase k(cat). Mechanistic studies support the idea that the differences in the substrates' kinetic activities results from differences in the expression of side-chain-pocket binding energy along the reaction coordinates. These results suggest that generating catalytic antibodies to transition-state analogues may be limited because the selective use of remote binding interactions cannot be programmed into transition-state analogues.
- Wade, Herschel,Scanlan, Thomas S.
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p. 11935 - 11941
(2007/10/03)
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- α-Amino Acids as Chiral Educts for Stereoselective Syntheses of Pyrrolidine and Pyrrolizidine Systems
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Homochiral functionalized pyrrolidine and pyrrolizidine systems have been achieved by stereoselective intramolecular 1,3-dipolar cycloaddition of homochiral nitrones, starting from homochiral amino acids, and by subsequent reduction of the obtained cycloadducts.
- Chiacchio, Ugo,Casuscelli, Franco,Corsaro, Antonio,Librando, Vito,Rescifina, Antonio,et al.
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p. 5689 - 5700
(2007/10/02)
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- Neurotrophic peptides
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A novel neurotrophic peptide of sequence, Ala-Ala-Asp-Ile-Ser-Gln-Trp-Ala-Gly-Pro-Leu, which exhibits biological activity enhancing acetylcholine synthesis in cholinergic neurons is isolated and purified from a water soluble fraction of hippocampal tissue in mammals. A derivative of the peptide having the same biological activity may be chemically synthesized using a conventional solid or liquid phase method. The peptide and derivative thereof are useful for the treatment of neurological degenerative disorders and dimentia.
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