259871-00-6Relevant articles and documents
Dependency of the regio- and stereoselectivity of intramolecular, ring-closing glycosylations upon the ring size
Claude, Patrick,Lehmann, Christian,Ziegler, Thomas
supporting information; experimental part, p. 1609 - 1619 (2012/01/06)
Phenyl 3,4,6-tri-O-benzyl-2-O-(3-carboxypropionyl)-1-thio-β-D- galactopyranoside (1) was condensed via its pentafluorophenyl ester 2 with 5-aminopentyl (4a), 4-aminobutyl (4b), 3-aminopropyl (4c) and 2-aminoethyl 4,6-O-benzylidene-β-D-glucopyranoside (4d), prepared from the corresponding N-Cbz protected glucosides 3a-d, to give the corresponding 2-[3- (alkylcarbamoyl)propionyl] tethered saccharides 5a-d. Intramolecular, ring closing glycosylation of the saccharides with NIS and TMSOTf afforded the tethered β(1→3) linked disaccharides 6a-c, the a(1→3) linked disaccharides 7a-d and the a(1→2) linked disaccharide 8d in ratios depending upon the ring size formed during glycosylation. No β(1→2) linked disaccharides were formed. Molecular modeling of saccharides 6-8 revealed that a strong aromatic stacking interaction between the aromatic parts of the benzyl and benzylidene protecting groups in the galactosyl and glucosyl moieties was mainly responsible for the observed regioselectivity and anomeric selectivity of the ring-closing glycosylation step.
Prearranged glycosides. Part 8. Intramolecular α-galactosylation via succinoyl tethered glycosides
Ziegler, Thomas,Dettmann, Ralf,Ariffadhillah,Zettl, Uwe
, p. 1079 - 1095 (2007/10/03)
Benzyl protected phenyl 1-thio-galactopyranoside donors which were tethered by a succinoyl linker at their positions 2 and 6, respectively, to position 3 of a blocked benzyl glucopyranoside acceptor with a 4-OH group solely afforded the corresponding α-(1→4)-linked disaccharides upon intramolecular glycosylation. 4,6-Siloxane protected mannosides react with rearrangement of the siloxane group under similar conditions.