- Un nouvel agent de glycosylation: l'anhydride trifluoromethanesulfonique. Synthese des α et β O-glycosyl-L-serine, -L-threonine et -L-hydroxyproline
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When 2,3,4,6-tetra-O-benzyl-D-glucopyranose, -D-galactopyranose and 2,3,4-tri-O-benzyl-D-xylopyranose were allowed to react in the cold in dichloromethane or acetonitrile as solvent in the presence of trifluoromethanesulfonic (triflic) anhydride, with methyl or benzyl esters of the N-(benzyloxycarbonyl)-L-serine, -L-threonine, and -L-hydroxyproline, an anomeric mixture of the corresponding O-glycosylaminoacids was obtained (55 to 90percent overall yield), with the α-anomer being predominant.The same experimental procedure was successfully applied to the condensation of the benzyl ester of the N-(benzyloxycarbonyl)-L-hydroxyproline with 2,3,4-tri-O-benzyl-L-arabinopyranose and 2,3,5-tri-O-benzyl-L-arabinofuranose affording the corresponding condensation products with similar yield.Pure α and β anomers were obtained after column chromatography or crystallization with 30 to 65percent yield.Hydrogenolysis of benzyl derivatives afforded the unprotected compounds.Optical rotation, (1)H and (13)C nmr were the main methods used to assess structure and stereochemistry.
- Lacombe, J. M.,Pavia A. A.,Rocheville, J. M.
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p. 473 - 481
(2007/10/02)
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