Hexulosuronic acid

Labeling experiments with l-deoxy-l-(dibenzylamino)-D-[l- C]-aruI>-mo-2-hexulosuronic acid [l- C] 112 indicated that the C label corresponded to the 5-methyl group of 111 (see Ref. 234). This is also consistent with a l-deoxy-2,3-dicarbonyl intermediate (115), and indicates that 111 is a decarboxylation product (see Scheme 22). The precise step entailing decarboxylation has not yet been determined. The carboxyl group could be carried through to ring closure (furanone formation). Such a step would provide a 2-carboxylate which is a /3-keto acid subject to ready decarboxylation. The labeling information and the initial steps of the mechanism in Scheme 22 are also consistent with the formation of 111 from D-[l- C]ribose and a secondary amine. ... 

WZ)o-3-Hexulosuronic acid D-Pyranose-/< rm, H-115 arafeino-2-Hexulosuronic acid, H-114 Hyalbiuronic acid N-Ac, H-127... 

Hexulosonic acid D-form, H-111 -3-Hexulosuronic acid a-D-Furanose-/orm 1,2-0-Isopropylidene,... 

Hexulosuronic acid D-Pyranose-/orm, H-115 Isoascorbic acid i.-form, 1-49... 

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