Heptoses, branched-chain

Two unusual glycosyl esters of cytidine 5 -pyrophosphate were found in extracts of Azotobacter vinelandii,62 The branched-chain, O-methylated heptose called vinelose was identified as the glycosyl component, and the structures 13 and 14 were assigned to these... 

SCHEME 13.73 Casiraghi s synthesis of branched-chain heptoses. 

The synthetic design based on the molybdic acid catalyzed carbon-skeleton rearrangement of the branched chain aldose as applied above to prepare sedo-heptulose has also been exploited for the synthesis of D-glycero-D-ido-octu ose [63]. The necessary branched-chain aldose 45,2-C-(hydroxymethyl)-D-g/ycero-D-gw/o-heptose,was obtained by the potassium carbonate catalyzed aldolization of the D-glycero-D-gulo-heiptose derivative 43 [64], which has an anchored configuration at C-2,by 2,3-0-isopropylidenation with formaldehyde and by subsequent deprotection of the aldolization product 44. 

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