Biomedical subjects

Andrew J Clark

Publications and source records attributed to Andrew J Clark.

4 recordsLinked to original sources

PubMed2006

Novel tertiary amine oxide surfaces that resist nonspecific protein adsorption.

Novel surfaces derivatized with tertiary amine oxides have been prepared and tested for their ability to resist nonspecific protein adsorption. The oxidation of tertiary amines supported on triazine units was carried out using mCPBA to give a format allowing conjugation of biologically active ligands alongside them. Adsorption to these surfaces was tested and compared to adsorption to a set of commercial and custom oligo-/poly(ethylene glycol) (OEG/PEG) supports by challenging them with a protein display library presented on bacteriophage lambda. The new class of amine oxide surfaces is found to compare favorably with the performance of the OEG/PEG supports in the prevention of nonspecific binding.

Adsorption↗

PubMed2006

Solid-supported copper catalysts for atom-transfer radical cyclizations: assessment of support type and ligand structure on catalyst performance in the synthesis of nitrogen heterocycles.

A range of solid supported pyridinemethanimine 9-11 and polyamine 12-15 ligands have been prepared on silica, polystyrene, and JandaJel supports. The CuCl and CuBr complexes of these supported ligands have been used to assess both the effect of the ligand type and the nature of the support upon a representative range of copper-mediated atom transfer 5-exo-trig 6, 24-25, 5-exo-dig 26, 4-exo-trig 28, and 5-endo-trig 27, 38 radical cyclizations to give nitrogen heterocycles. In addition, the effect of the nature of the support on the stereochemical outcome of the 5-exo cyclization of 25 has been probed. Generally, it was found that the type of support (e.g., polystyrene, silica, or JandaJel) had very little effect upon the efficiency and selectivity of the processes but that the nature of the ligand type immobilized was the important factor. Thus, the 5-exo cyclization of 6 and 24-26 proceeded more rapidly with the PMI ligands 9-11, whereas 4-exo cyclizations 28 and 5-endo radical polar crossover reactions 27 and 38 proceeded more efficiently with the JJ-TEDETA ligand 15. The efficiency of the supported ligands was also compared to their solution counterparts 4 and 5. The reusability of P-PMDETA ligand system 13 was assessed in the cyclization of 6.

Catalysis↗

PubMed2003

Oxidative 5-endo cyclization of enamides mediated by ceric ammonium nitrate.

[reaction: see text] Ceric ammonium nitrate mediates the oxidative 5-endo radical-polar crossover reactions of beta-enamide esters to give 5,5-C,O-disubstituted-gamma-lactams. Trapping of the intermediate cations leads to 5-hydroxy- or 5-alkoxy-gamma-lactams depending upon the reaction conditions. The methodology was used to synthesize the basic heterocyclic ring fragments of the natural products L-755,807, Quinolacticin C, and PI-091.

Amides↗

PubMed2002

Atom transfer radical cyclisation reactions mediated by copper complexes.

This article describes recent advances in the use of copper complexes in mediating atom transfer radical cyclisation reactions (ATRC). Recent developments have included the design of activated complexes which mediate the cyclisation of tri-, di-, and mono-halo derived substrates at ambient temperatures. Using this methodology, cyclisation to give a variety of ring sizes (4-18 membered rings) has been demonstrated. In addition tandem and radical-polar crossover reactions have also been developed. The design of solid supported and perfluorous complexes that mediate cyclisations may make this approach to the synthesis of rings more attractive towards industrial applications.

Journal Article↗