Search results for "combinatorial"

Improved synthesis and application of conjugation-amenable polyols from d-mannose

2019

A series of polyhydroxyl sulfides and triazoles was prepared by reacting allyl and propargyl d-mannose derivatives with selected thiols and azides in thiol-ene and Huisgen click reactions. Conformational analysis by NMR spectroscopy proved that the intrinsic rigidity and linear conformation of the mannose derived polyol backbone is retained in the final click products in solution. Single crystal X-ray structure determination of one of the compounds prepared further verified that the linear conformation of the polyol segment is also retained in the solid state. In addition, an improved method for direct Barbier-type propargylation of unprotected d-mannose is reported. The new reaction protoc…

Outstandingly robust anodic dehydrogenative aniline coupling reaction

2020

Abstract Oxidative treatment of anilines usually leads to the formation of black polymers, often referred to as “aniline black”. This over-oxidation is hardly controllable and also a challenging task in the anodic conversion of anilines. Here, a quick and efficient access to valuable building blocks by anodic cross- and homo-coupling of aniline and benzidine derivatives is reported. This electrosynthesis is easily performed in a simple undivided cell using constant current conditions. The key to the observed outstanding performance and robustness of this system is attributed to the used solvent 1,1,1,3,3,3-hexafluoroisopropanol. The extraordinary performance over a broad range of current de…

Catalytic Diastereo- and Enantioselective Synthesis of 2-Imidazolinones.

2019

Chiral cyclic ureas (2-imidazolinones) were prepared by the reaction of nitrones and isocyanoacetate esters using a multicatalytic system that combines a bifunctional Brønsted base-squaramide organocatalyst and Ag+ as a Lewis acid. The reaction could be achieved with a range of nitrones derived from aryl- and cycloalkylaldehydes with moderate diastereo- and good enantioselectivity. A plausible mechanism involving an initial formal [3 + 3] cycloaddition of the nitrone and isocyanoacetate ester, followed by rearrangement to an aminoisocyanate and cyclization to the imidazolinone, is proposed.

Solution and fluorous phase synthesis of β,β-difluorinated 1-amino-1-cyclopentane carboxylic acid derivatives

2008

An efficient protocol for the preparation of β,β-difluorinated 1-amino-1-cyclopentane carboxylic acid derivatives was developed. 2,2-Difluro-4-phenyl-3-butenoic acid 6 was used as substrate for the preparation of the starting vinyl difluoro imino esters 8. The key steps of this methodology rely on the chemo- and diastereoselective addition of allylzinc bromides over the iminic functionality of 8 and subsequent RCM reaction. This synthetic sequence was successfully applied to fluorous synthesis.

Clickable poly-L-lysine for the formation of biorecognition surfaces

2019

Biomolecules are immobilized onto surfaces employing the fast and stable adsorption of poly-l-lysine (PLL) polymers and the versatile copper-free click chemistry reactions. This method provides the combined advantages of versatile surface adsorption with density control using polyelectrolytes and of the covalent and orthogonal immobilization of biomolecules with higher reaction rates and improved yields of click chemistry. Using DNA attachment as a proof of concept, control over the DNA probe density and applicability in electrochemical detection are presented.

A two-step synthesis of new macrobicyclic aza-ligands starting from “trans”dioxocyclam as diprotected macrocycle

1997

Abstract A rapid and convenient synthesis of two small aza-cryptands containing a 1,4,8,11-tetraazacyclotetradecane backbone is reported. This strategy can be applied to the preparation of many other aza-cages by varying the nature of the cross linker. Moreover, the two remaining secondary amine sites may allow the functionalization of these ligands or their grafting on a polymer.

Fluorenylmethoxycarbonyl-ProtectedO-Glycosyl-N-methyl Amino Acids: Building Blocks for the Synthesis of Conformationally Tuned Glycopeptide Antigens

2015

Peptide antibiotics often contain N-methylated amino acids. These N-methylamino components enhance the metabolic stability and strongly influence the conformational behavior of these peptide drugs. N-Methyl-O-glycosyl amino acids, in particular, threonine and serine derivatives, are unknown so far. Fmoc-protected N-methyl-O-glycosyl-threonine and -serine building blocks, including sialyl TN antigens, have been synthesized for the first time by converting the Fmoc-protected O-glycosyl amino acids or their tert-butyl esters into the corresponding oxazolidinones followed by reductive ring-opening. These new components are considered interesting for the construction of modified mucin glycopepti…

Cover Feature: Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells (ChemBioChem 9/2018)

2018

Noncovalent molecular imprinting: antibody-like molecular recognition in polymeric network materials

1997

Abstract Molecular imprinting techniques allow the preparation of polymeric receptors which bind small molecules with affinities and selectivities of the same order as those observed in the binding of antigens by antibodies. The molecular imprinting technology has now reached a stage where the commercial use of imprinted materials is being assessed, notably for separations requiring strong and selective binding of small molecules. This development is driven by the potential advantages of polymeric receptors over biological in terms of stability, capacity, cost and ease of preparation. In this short review the state of the art of noncovalent imprinting is summarised indicating a few areas in…

Chemical Strategies for the Synthesis of Protein–Polymer Conjugates

2012

Protein-polymer conjugates have achieved tremendous attention in the last few years. The synergistic combination of properties has led to certain advantages in bio-applications. Over the past few years, numerous chemical strategies have been developed to conjugate different synthetic polymers onto proteins, most of which can be summarized within the scope of click-chemistry. Here we highlight conjugation strategies based on available functional groups present on the synthetic polymer and existing groups of proteins from the natural pool. In particular, the chapter organizes the various possible reactions by classes of functional groups present on protein surfaces, deriving from selected ami…