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Reductive Cleavage of Glycosides, Stereochemistry of Trapping of Cyclic Oxonium Ions
Titel:
Reductive Cleavage of Glycosides, Stereochemistry of Trapping of Cyclic Oxonium Ions
Auteur:
Rolf, David Bennek, John A. Gray, Gary R.
Verschenen in:
Journal of carbohydrate chemistry
Paginering:
Jaargang 2 (1983) nr. 4 pagina's 373-383
Jaar:
1983
Inhoud:
Reductive cleavage of the glycosidic carbon-oxygen bonds of methyl 2,3,4,6-tetra-O-methyl-β-d-glucopyranoside (1), methyl 2,3,4,6-tetra-O-methyl-α-d-glucopyranoside (2), permethylated cellulose (6) and permethylated cyclohexaamylose (7) was carried out in the presence of deuteriotriethylsilane, and the configuration of deuterium in the l-deuterio-1,5-anhydro-d-glucitol derivatives (4, 5 and 9, 10) that were produced was established by 1H- and 2H-NMR spectroscopy. All reductions were carried out with boron trifluoride etherate as the catalyst as originally reported [D. Rolf and G. R. Gray, J. Am. Chem. Soc., 104, 3539 (1982)], as well as with trimethylsilyl trifluoromethanesulfon-ate which we now report efficiently catalyzes the regiospecific reductive cleavage of glycosides. Spectroscopic studies revealed that the configuration of deuterium in the products was independent of the configuration of the starting glycoside. The predominant (∼95%) axial configuration observed leads us to propose that free oxonium ions (3 and 8) are formed as intermediates in these reductions.
Uitgever:
Taylor & Francis
Bronbestand:
Elektronische Wetenschappelijke Tijdschriften
Details van artikel 108 van 178 gevonden artikelen