A surprising C-4 epimerization of 5-deoxy-5-sulfonylated pentofuranosides under Ramberg-Baecklund reaction conditions
Treatment of methyl 5-deoxy-2,3-O-isopropylidene-5-(benzylsulfonyl)-β-d-ribofuranoside with CBr2F2-KOH/Al2O3 afforded the corresponding olefinic sugar. The methyl- and the isopropyl-analogues in contrast underwent epimerization at C-4 to generate the α-l-lyxo derivatives.
Pal, Tarun Kumar,Pathak, Tanmaya
scheme or table
p. 2826 - 2829
(2009/04/11)
Reaction of sugar thiocyanates with Grignard reagents. New synthesis of thioglycosides
Glycosyl thiocyanates having hydroxyl groups protected with acetyl or benzoyl groups react readily at -40°C with Grignard reagents to afford the corresponding alkyl or aryl thioglycosides in good yields. Monosaccharide derivatives having the SCN grouping at other positions form under similar conditions thioethers. Axial thiocyanates do not react. Elevated temperatures induce side reactions leading to mercaptans.
Pakulski, Zbigniew,Pierozynski, Donat,Zamojski, Aleksander
p. 2975 - 2992
(2007/10/02)
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