Nucleoside synthesis from 3-alkylated sugars: role of 3beta-oxy substituents in directing nucleoside formation.
Using Vorbrüggen's protocol, reaction of persilylated uracil with xylofuranose derivatives having 3beta-oxy-3alpha-alkyl substitution produced both alpha- and beta-nucleosides. Only the beta-nucleosides were formed from substrates having the reverse stereochemistry at C-3 or lacking the 3-alkyl substituent. Participation of the 3beta-oxy substituent in stabilizing the incipient C-1 carbonium ion (or oxonium ion) intermediate has been suggested from analysis of energy-minimized conformations.
Sahabuddin
Sk
S
Department of Medicinal Chemistry, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata, 700 032, India. sbmandal@iicb.res.in.
Ghosh
Ramprasad
R
Achari
Basudeb
B
Mandal
Sukhendu B
SB
D000478:Alkylation; D002241:Carbohydrates / Q000737:chemistry*; D015394:Molecular Structure; D009705:Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction
D002241:Carbohydrates; D009705:Nucleosides