Chemistry Research Collection

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Now showing 1 - 5 of 222
  • Publication
    Preparation of iminosugars from aminopolyols via selective oxidation using galactose oxidase
    (Royal Society of Chemistry (RSC), 2022-11-07) ; ; ;
    Minimally protected aminopolyols are novel substrates for the galactose oxidase variant F2. Site-selective oxidation proceeds at the terminal primary alcohol, followed by spontaneous cyclisation to afford stable hemiaminal/hemiacetal anomers of the piperidine and azepane scaffolds, with isolated yields of up to 94%. Simultaneous deprotection and reduction occured readily to afford valuable and biologically relevant iminosugars.
      1
  • Publication
    Transaminase-Mediated Amine Borrowing via Shuttle Biocatalysis
    (American Chemical Society (ACS), 2022-01-14) ; ; ;
    Shuttle catalysis has emerged as a useful methodology for the reversible transfer of small functional groups, such as CO and HCN, and goes far beyond transfer hydrogenation chemistry. While a biocatalytic hydrogen-borrowing methodology is well established, the biocatalytic borrowing of alternative functional groups has not yet been realized. Herein, we present a new concept of amine borrowing via biocatalytic shuttle catalysis, which has no counterpart in chemo-shuttle catalysis and allows efficient intermolecular amine shuttling to generate reactive intermediates in situ. By coupling this dynamic exchange with an irreversible downstream step to displace the reaction equilibrium in the forward direction, high conversion to target products can be achieved. We showcase the potential of this amine-borrowing methodology using a biocatalytic equivalent of both the Knorr-pyrrole synthesis and Pictet–Spengler reaction.
      3
  • Publication
    Combining bio- and organocatalysis for the synthesis of piperidine alkaloids
    (Royal Society of Chemistry (RSC), 2022-02-07) ; ; ;
    There is continued interest in developing cascade processes for the synthesis of key chiral building blocks and bioactive natural products (or analogues). Here, we report a hybrid bio-organocatalytic cascade for the synthesis of a small panel of 2-substituted piperidines, relying on a transaminase to generate a key reactive intermediate for the complexity building Mannich reaction.
      6Scopus© Citations 4
  • Publication
    The Potential for Hydrolysed Sheep Wool as a Sustainable Source of Fertiliser for Irish Agriculture
    Suppressed wool prices in Ireland over the last number of years has led to situations where the cost of shearing animals is greater than the wools’ value, leading to net losses per animal for farmers. Populations of sheep in Ireland and nutrient values of wool from literature sources were used to determine the quantity of nutrients that could be produced on an annual basis using hydrolysis techniques. Results of this study suggest that up to 15.8% of the nitrogen required to produce Ireland’s cereal crops can be met annually using hydrolysed sheep wool in an economically feasible manner along with considerable amounts of sulphur, zinc, and copper. Most of the cost associated with the process is the purchasing of wool from farmers at an economically favourable level for farmers. Based on the spatial distribution of these animals, the town of Athlone is the most suitable location for a processing facility.
      60Scopus© Citations 1
  • Publication
    Graphene oxide modulates inter-particle interactions in 3D printable soft nanocomposite hydrogels restoring magnetic hyperthermia responses
    Hydrogels loaded with magnetic iron oxide nanoparticles that can be patterned and which controllably induce hyperthermic responses on AC-field stimulation are of interest as functional components of next-generation biomaterials. Formation of nanocomposite hydrogels is known to eliminate any Brownian contribution to hyperthermic response (reducing stimulated heating) while the Néel contribution can also be suppressed by inter-particle dipolar interactions arising from aggregation induced before or during gelation. We describe the ability of graphene oxide (GO) flakes to restore the hyperthermic efficiency of soft printable hydrogels formed using Pluronics F127 and PEGylated magnetic nanoflowers. Here, by varying the amount of GO in mixed nanocomposite suspensions and gels, we demonstrate GO-content dependent recovery of hyperthemic response in gels. This is due to progressively reduced inter-nanoflower interactions mediated by GO, which largely restore the dispersed-state Néel contribution to heating. We suggest that preferential association of GO with the hydrophobic F127 blocks increases the preponderance of cohesive interactions between the hydrophilic blocks and the PEGylated nanoflowers, promoting dispersion of the latter. Finally we demonstrate extrusion-based 3D printing with excellent print fidelity of the magnetically-responsive nanocomposites, for which the inclusion of GO provides significant improvement in the spatially-localized open-coil heating response, rendering the prints viable components for future cell stimulation and delivery applications.
      224Scopus© Citations 5