C-disaccharides of ketoses

Streicher, Hansjorg, Geyer, Armin and Schmidt, Richard R (1996) C-disaccharides of ketoses. Chemistry - A European Journal, 2 (5). pp. 502-510. ISSN 0947-6539

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Abstract

Reaction of gluconolactone 2 with allylmagnesium bromide at low temperatures afforded ketopyranose 3, which could easily be converted into open-chain ketoses (R)-6 and (S)-6. Their reaction with lithioacetylide 9 afforded propargylic alcohol derivatives (R)-10 and (S)-10, which could not be cyclized directly to the desired C-ketosides. They were converted by standard procedures into (R)-14 and (S)-14 and then into dicobalthexacarbonyl complexes (R)-16 and (S)-16. A facile acid-catalyzed ring closure gave the desired C-ketosides (R)-18 alpha/beta and (S)-18 alpha/beta, respectively, in different ratios. In order to demonstrate that removal of the protective groups and hydrogenation of the CC triple bond proceed smoothly, (R)-18% was transformed into the deprotected target molecule (R)-1x. For the assignment of the new chiral centers at C-2/2' and at C-8, (S)-18 alpha was transformed into azido derivative (S)-22 alpha, which underwent intramolecular cycloaddition to afford the spiro derivative (S)-25 alpha. Because of the conformational constraints in this molecule, unequivocal configurational assignment was possible with the help of NMR data.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Hans Streicher
Date Deposited: 06 Feb 2012 18:11
Last Modified: 12 Jun 2012 12:31
URI: http://sro.sussex.ac.uk/id/eprint/15134
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