SYNTHESIS OF A 3-DEOXY-D-ARABINO-2-HEPTULOSONIC ACID-DERIVATIVE

The synthesis of a selectively protected 3-deoxy-D-arabino-2-heptulosonic acid, 9, from a noncarbohydrate precursor was achieved in six steps (19% yield) from a chiral, gamma,delta-epoxy beta-hydroxy ester, 3a, readily available from the corresponding alpha,beta-epoxy aldehyde. The product was obtained through a Lewis acid-mediated stereocontrolled lactonization of 3a followed by a two-step procedure: synthesis of Weinreb's amide 5a and lithiothiazole nucleophilic attack allowing the introduction of the masked aldehydo frame.