Directed and Efficient Syntheses of β(1→4)-Linked Galacto-Oligosaccharides

Autor: Siegfried Peters, Frieder W. Lichtenthaler, Markus Oberthür
Rok vydání: 2001
Předmět:
Zdroj: European Journal of Organic Chemistry. 2001:3849-3869
ISSN: 1099-0690
1434-193X
DOI: 10.1002/1099-0690(200110)2001:20<3849::aid-ejoc3849>3.0.co;2-q
Popis: Straightforward, preparatively efficient procedures are described for the construction of β(14)-intergalactosidic linkages up to the hexasaccharide level. Key elements were the use of phenylthio and/or phenyl sulfoxide functionalities for glycosylations and a judiciously designed blocking group pattern for donor and acceptor alike: pivaloyl protection at O-2 for securing β-selectivity, sterically undemanding allyl or benzyl groups at O-3 and O-6 to minimise the steric bulk around the unreactive galactosyl-4-OH, the p-methoxyphenyl moiety, readily replaceable by SPh, as an intermediate anomeric substituent, and an acetyl group for temporary protection of the terminal Gal-4-OH. This strategy lends itself to iterative block synthesis and interchange of donors and acceptors, thereby demonstrating the broad scope and generality of the overall approach. Although predicted by molecular modelling, inclinations towards starch-like coiling could not so far be verified in any of the galacto-tetra-, -penta-, or -hexaoses or their p-methoxyphenyl glycosides.
Databáze: OpenAIRE
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