D-Ribono-l,4-lactone

Addition of lithiated heterocycles to aldonolactones yields carbon-linked nucleosides (56). Thus, the reaction of 2,3 5,6-di-O-isopropylidene-L-gu-lono-1,4-lactone (9b) or 2,3-O-isopropylidene-D-ribono-l,4-lactone (16a) with various lithiated heterocycles gave gulofuranosyl derivatives 53a-g or ribofuranosyl derivatives 54b,c. Gulonolactols 53a-g and ribonolactols 54b,c were acetylated with acetic anhydride in pyridine to yield their acetyl derivatives. The stereochemistry of compounds 53a-g and 54b,c was discussed in terms of the Cotton effect of circular-dichroism curves of the ring-opened alcohols formed upon reduction by sodium borohydride. The configuration at C-l of 53g was proved by means of X-ray analysis (57,58). 

C-Methyl-D-erythritol 4-phosphate (4), a key isoprenoid precursor in the mevalonate-independent pathway leading to isopentenyl diphosphate, has been synthesized in eight steps from 1,2-0-isopropylidene-a-D-xylofuranose in such a way as to facilitate the incorporation of C or radiolabels. Syntheses of the non-phosphorylated derivative, 5, and its L-threitol diastereomer, 6, from d-glucose and D-galactose respectively, have also been reported. 3p-(5 -D-Ribityl)cholestane (7), a putative biological precursor for fossil 3-alkylsteranes, has been synthesized from cholestanone by the stepwise and stereoselective construction and subsequent reductive opening of a 3p-(5 -deoxy-5 -yl-D-ribono-l,4-lactone) substituent/... 

Acetone reacts with carbohydrates in the presence of an acid catalyst to form products that are commonly referred to as isopropylidene or acetonide derivatives. The carbohydrate D-ribono-(l,4)-lactone reacts with acetone in the presence of hydrochloric... 

Lactone 2-C-Methyl-D-ribono-l,4-lactone. a-Glucosaccharin. Glucosac-charino-y-lactone. Glucosaccharinic lactone. Saccharin ll [492-30-8]... 

Deoxy-D-ribono-l,4-lactone 3,5-bis(triphosphate), D-674 2-Deoxy-L-ribono-1,4-lactone, D-674 2-Deoxy-D-ribono-1,4-lactone, D-674 Deoxyribonucleic acid, D-361... 

Bromo-5-deoxy-2,3-0-isopropylidene-D-ribono-l,4-lactone, B-91 5-Bromo-5-deoxy-D-l, 4-ribonolactone, B-91... 

The nitrile oxide (79) generated from the D-ribose oxime (80) can be trapped with dimethylacetylene dicarboxylate (DMAD) to form the cycloadduct (81) (Scheme 17). In the absence of DMAD the D-ribono-l,4-lactone oxime (82) is... 

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