Semisynthesis of long-chain alkyl ether derivatives of sulfated oligosaccharides via dibutylstannylene acetal intermediates.
Long-chain alkyl ether derivatives of sulfated oligosaccharides were semisynthesized as follows: two naturally occurring red seaweed galactans (neutral agarose and kappa-carrageenan) were submitted to partial reductive hydrolysis to give neutral and sulfated oligosaccharide alditols. The neutral disaccharide alditol (1) and its trityl ether (5) were sulfated and/or alkylated through formation of their dibutylstannylene or (bis)dibutylstannylene acetals. In these reactions, the dibutylstannylene acetals of the terminal 1,2-diols in the alditol units were more reactive than those formed on the cis-diols of the galactopyranosidic units. This property allowed the regioselective monoalkylation of a neutral tetrasaccharide alditol (2), which contained eleven free hydroxyl groups, the highest selectivity ever observed with dibutylstannylene acetals. An alkylated/sulfated derivative (11) was also obtained through the regioselective alkylation of a naturally sulfated disaccharide alditol (10, a kappa-carrageenan derivative).
Department of Chemistry, Dalhousie University, Halifax, NS, Canada.
Alan G
AG
Gonçalves
Miguel D
MD
Noseda
M E R
ME
Duarte
T Bruce
TB
Grindley
D000080:Acetals / Q000737:chemistry*; D000478:Alkylation; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004987:Ethers / Q000138:chemical synthesis* / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D009947:Organotin Compounds / Q000737:chemistry*; D012685:Sepharose / Q000031:analogs & derivatives / Q000737:chemistry
D000080:Acetals; D004987:Ethers; D006027:Glycosides; D009844:Oligosaccharides; D009947:Organotin Compounds; C056189:di-n-butyltin; D012685:Sepharose