title: A convenient approach for access to both carbapentofuranoses and carbahexopyranoses. Stereocontrolled synthesis of enantiopure carba-D-ribofuranoses, carba-D-arabinofuranoses and carba-L-gulopyranose.
abstract: A new approach to carbasugars in enantiomerically pure form is reported. The key step involves ring-closing metathesis of dienols 6 derived from a (R)-(+)-glyceraldehyde derivative 4 to form the substituted cyclopentenol 9 and cyclohexenol 34a. Stereocontrolled addition of hydroxyl groups followed by conversion of the ketal unit to hydroxymethyl group in these intermediates led to carbapentoses and -hexoses. Stereoselectivity during introduction of hydroxyl groups arises through the steric hindrance posed by the allylic substituents. A remarkable feature of the present approach is the accessibility of both d- and l-series of carbapentoses as illustrated by the synthesis of beta-D- and beta-L-carbaribofuranoses 17 and 20, respectively. Carba-alpha-D-ribofuranose 25, the biosynthetic intermediate to the antibiotic aristeromycin, has also been synthesized from the same cyclopentenol 9. Functional group manipulation in the cyclopentenol 9a also enabled access to carbaarabinofuranose 32. The present synthetic strategy can be extended for the synthesis of carbahexopyranose, as illustrated by the synthesis of carba-alpha-L-gulopyranose 40b.
authors.affiliation: Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India. ocsg@iacs.res.in
authors.forename: Subrata
authors.initials: S
authors.lastname: Ghosh
authors.forename: Tanurima
authors.initials: T
authors.lastname: Bhaumik
authors.forename: Niladri
authors.initials: N
authors.lastname: Sarkar
authors.forename: Abhijit
authors.initials: A
authors.lastname: Nayek
mesh_terms: D003511:Cyclohexanols / Q000138:chemical synthesis* / Q000737:chemistry; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009005:Monosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D003511:Cyclohexanols; D003517:Cyclopentanes; D005663:Furans; D009005:Monosaccharides; D011714:Pyrans; C517331:carbaarabinofuranose; C517330:carbagulopyranose; C517329:carbaribofuranose