Phenyl thioglycopyranosides with various protecting groups (acetal, ether, ester) underwent reductive lithiation at C-1, followed by rapid elimination of the 2-substituent, when treated with lithium naphthalenide in tetrahydrofuran at low temperature. Thus, pyranoid glycal derivatives with acid-labile protecting groups were obtained in excellent yields. Glycopyranosyl phenyl sulphones were prepared quantitatively by oxidation of the corresponding phenyl thioglycosides with catalytic amounts of ruthenium trichloride in the presence of sodium periodate in a biphasic solvent system. These compounds also gave rise to pyranoid glycal derivatives in excellent yields when treated with lithium naphthalenide in tetrahydrofuran at low temperature. A β-linked 2′-deoxydisaccharide glycal derivative was also prepared from the corresponding disaccharide phenyl thioglycoside. Phenyl thioglycopyranosides carrying a 2-xanthate group underwent a radical reductive elimination when treated with tributyltin hydride, to afford glycal derivatives in good yields under neutral conditions. © 1989.
Preparation of pyranoid glycal derivatives from phenyl thioglycosides and glycosyl phenyl sulphones
MARRA, Alberto;
1989
Abstract
Phenyl thioglycopyranosides with various protecting groups (acetal, ether, ester) underwent reductive lithiation at C-1, followed by rapid elimination of the 2-substituent, when treated with lithium naphthalenide in tetrahydrofuran at low temperature. Thus, pyranoid glycal derivatives with acid-labile protecting groups were obtained in excellent yields. Glycopyranosyl phenyl sulphones were prepared quantitatively by oxidation of the corresponding phenyl thioglycosides with catalytic amounts of ruthenium trichloride in the presence of sodium periodate in a biphasic solvent system. These compounds also gave rise to pyranoid glycal derivatives in excellent yields when treated with lithium naphthalenide in tetrahydrofuran at low temperature. A β-linked 2′-deoxydisaccharide glycal derivative was also prepared from the corresponding disaccharide phenyl thioglycoside. Phenyl thioglycopyranosides carrying a 2-xanthate group underwent a radical reductive elimination when treated with tributyltin hydride, to afford glycal derivatives in good yields under neutral conditions. © 1989.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
