Casuarine stereoisomers from achiral substrates: Chemoenzymatic synthesis and inhibitory properties

A straightforward chemoenzymatic synthesis of four uncovered casuarine stereoisomers is described. The strategy consists of l-fuculose-1-phosphate aldolase F131A-variant-catalyzed aldol addition of dihydroxyacetone phosphate to aldehyde derivatives of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) and its enantiomer (LAB) and subsequent one-pot catalytic deprotection-reductive amination. DAB and LAB were obtained from dihydroxyacetone and aminoethanol using d-fructose-6-phosphate aldolase and l-rhamnulose-1-phosphate aldolase catalysts, respectively. The new ent-3-epi-casuarine is a strong inhibitor of α-d-glucosidase from rice and of rat intestinal sucrase. © 2014 American Chemical Society.