A synthesis of ammonium 3-deoxy-(d)-manno-2-octulosonate (ammonium kdo) from (d)-mannose via cobaloxime-mediated radical alkyl-alkenyl cross coupling

We report a synthesis of the ammonium salt of the 8-carbon monosaccharide 3-deoxy-(d)-manno-2-octulosonic acid (KDO) starting from (d)-mannose. The key C-C bond construction in our synthetic strategy is a novel alkyl cobaloxime mediated radical alkyl-alkenyl cross coupling of α-ethoxyacrylonitrile with an alkyl cobaloxime derivative of D-mannose. KMnO₄ unmasking of the latent functionality in the α-ethoxyacrylonitrile moiety provides the α-hydroxyester moiety necessary for completion of the KDO synthesis.