Regio- and stereoselective glycosylation: synthesis of 5-haloimidazole alpha-ribonucleosides.
We describe the synthesis of novel 5-haloimidazole ribonucleosides as precursors of modified cobalamins. A regio- and stereoselective glycosylation of protected ribose with silylated 4(5)-haloimidazoles produces 5-haloimidazole ribonucleosides predominantly in the alpha-configuration (60-75%) without any 4-substituted imidazole ribonucleoside. The structure of the 5-fluoroimidazole ribonucleoside was confirmed by X-ray crystallography and 2D NMR spectroscopy.
Chandra
Tilak
T
Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, USA.
Zou
Xiang
X
Valente
Edward J
EJ
Brown
Kenneth L
KL
D006031:Glycosylation; D007093:Imidazoles / Q000737:chemistry*; D008968:Molecular Conformation; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D007093:Imidazoles; D012263:Ribonucleosides