An efficient one‐potprotocol for the direct preparation of thioglycosides starting from unprotected reducing sugars via S‐glycosyl isothiouronium salts is reported. In this one‐pot methodology, BF3 · OEt2 has been used as a general catalyst for both per‐O‐acetylation of sugars and conversion of sugar per‐O‐acetates into S‐glycosyl isothiouronium salts, which was allowed to react with alkylating agents
A Through-process for the Preparation of Methyl Per-<i>O</i>-acetyl 1-Thio-glycosides from Aldoses
作者:Shinkiti Koto、Toyosaku Yoshida、Kazuhiro Takenaka、Shonosuke Zen
DOI:10.1246/bcsj.55.3667
日期:1982.11
d-Glucose, d-galactose, d-mannose, d-xylose, l-arabinose, l-fucose, l-rhamnose, maltose, cellobiose, lactose, d-glucosamine, d-galactosamine, and d-mannosamine were converted into the corresponding methyl per-O-acetyl 1-thioglycopyranosides by way of a three-step (acetobromination, methylthioation, and acetylation) through-process in a single vessel.
Streamlined Synthesis of Per-<i>O</i>-acetylated Sugars, Glycosyl Iodides, or Thioglycosides from Unprotected Reducing Sugars<sup>1</sup>
作者:Balaram Mukhopadhyay、K. P. Ravindranathan Kartha、David A. Russell、Robert A. Field
DOI:10.1021/jo048890e
日期:2004.10.1
Solvent-free per-O-acetylation of sugars with stoichiometric acetic anhydride and catalytic iodine proceeds in high yield (90-99%) to give exclusively pyranose products as anomeric mixtures. Without workup, subsequent anomeric substitution employing iodine in the presence of hexamethyldisilane (i.e., TMS-I generated in situ) gives the corresponding glycosyl iodides in 75-95% isolated yield. Alternatively, and without workup, further treatment with dimethyl disulfide or thiol (ethanethiol or thiocresol) gives anomerically pure thioglycosides in more than 75% overall yield.