Chemoenzymatic asymmetric synthesis of the metallo-β-lactamase inhibitor aspergillomarasmine A and related aminocarboxylic acids

Metal-chelating aminocarboxylic acids are being used in a broad range of domestic products and industrial applications. With the recent identification of the fungal natural product aspergillomarasmine A as a potent and selective inhibitor of metallo-beta-lactamases and a promising co-drug candidate to fight antibiotic-resistant bacteria, the academic and industrial interest in metal-chelating chiral aminocarboxylic acids further increased. Here, we report a biocatalytic route for the asymmetric synthesis of aspergillomarasmine A and various related aminocarboxylic acids from retrosynthetically designed substrates. This synthetic route highlights a highly regio- and stereoselective carbon-nitrogen bond-forming step catalysed by ethylenedi-amine-N,N'-disuccinic acid lyase. The enzyme shows broad substrate promiscuity, accepting a wide variety of amino acids with terminal amino groups for selective addition to fumarate. We also report a two-step chemoenzymatic cascade route for the rapid diversification of enzymatically prepared aminocarboxylic acids by N-alkylation in one pot. This biocatalytic methodology offers a useful alternative route to difficult aminocarboxylic acid products.