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An in vitro-in vivo sequential cascade for the synthesis of iminosugars from aldoses

2021-06-15, Kuska, Justyna, Taday, Freya, Yeow, Kathryn, Ryan, James, O'Reilly, Elaine

Here, we report a chemoenzymatic approach for the preparation of a small panel of biologically important iminosugars from readily available aldoses. Our approach involves an in vitro transaminase-mediated amination of aldoses in combination with an in vivo selective oxidation of the chemically protected transaminase products, using Gluconobacter oxydans DSM 2003 whole cells. Chemically catalysed deprotection and reduction steps afford a selection of valuable iminocyclitols.

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Combining bio- and organocatalysis for the synthesis of piperidine alkaloids

2022-02-07, Taday, Freya, Cairns, Ryan, O'Connell, Adam, O'Reilly, Elaine

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.

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Publication

Transaminase-Mediated Amine Borrowing via Shuttle Biocatalysis

2022-01-14, Taday, Freya, Ryan, James, O’Sullivan, Rachel, O'Reilly, Elaine

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.