Stereocontrolled Synthesis of α-C-Galactosamine Derivatives via Chelation-Controlled C-Glycosylation
- 21 March 1998
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Organic Chemistry
- Vol. 63 (8) , 2507-2516
Abstract
The samarium diiodide-promoted reduction of 2-deoxy-2-acetamidogalactosyl pyridyl sulfone alpha-5 with ketones or aldehydes under Barbier conditions led unexpectedly to the stereoselective synthesis of alpha-C-galactosamine derivatives in good yields. With carbonyl substrates, alpha:beta selectivities ranged from 20:1 to 5:1, and with aldehydes a stereoselectivity of approximately 5:1 was observed at C7 in favor of the S-isomer. The stereochemical preference of these C-glycosylation reactions is explained by the intermediacy of an alpha-oriented anomeric glycosyl samarium(III) compound that is stabilized via chelation of the metal ion to the C2-acetamido group.Keywords
This publication has 30 references indexed in Scilit:
- 1,2‐cis‐C‐glycoside synthesis by samarium diiodide‐promoted radical cyclizationsChemistry – A European Journal, 1997
- Samarium(II) Iodide Promoted Ketone-Olefin Couplings Chelation-Controlled by (Alkoxycarbonyl)amino GroupsSynlett, 1996
- The stereospecific synthesis of methyl α-C-mannobioside: a potential inhibitor of M. tuberculosis binding to human macrophagesChemical Communications, 1996
- Samarium Iodide Induced Intramolecular C‐Glycoside Formation: Efficient Radical Formation in the Absence of an AdditiveAngewandte Chemie International Edition, 1994
- Conformational effects in 2‐deoxyglucopyranos‐1‐yl radicalsEuropean Journal of Inorganic Chemistry, 1990
- Dimerization of carbohydrate radicalsEuropean Journal of Organic Chemistry, 1988
- Electron spin resonance spectroscopic investigation of carbohydrate radicals. Part 2. Conformation and configuration in pyranos-1-yl radicalsJournal of the Chemical Society, Perkin Transactions 2, 1986
- Bausteine von Oligosacchariden, XXII1) Synthese der Trisaccharid‐Sequenz α‐D‐GlcNAc‐(1→4)‐β‐D‐Gal(1→4)‐D‐GlcNAc aus blutgruppenaktiven SubstanzenEuropean Journal of Inorganic Chemistry, 1981
- Photochemistry of carbohydrate derivatives. Part I. Photolytic decomposition of glucopyranosyl phenyl sulphone acetatesJournal of the Chemical Society, Perkin Transactions 1, 1974
- Meisenheimer rearrangement of methoxymethyl phenyl sulfoxide. Formation and disproportionation of methoxymethyl benzenesulfenateJournal of the American Chemical Society, 1972