Synthesis of the methyl thioglycosides of 2-,3-, and 4-deoxy-l-fucose

✍ Scribed by Akira Hasegawa; Takashio Ando; Mitsutoshi Kato; Hideharu Ishida; Makoto Kiso

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 883 KB
• Volume: 257
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(94)84107-1

✦ Synopsis

Methyl thioglycoside derivatives of 2-, 3-, and 4-deoxy-L-fucopyranose have been prepared as glycosyl donors for the synthesis of sialyl IA? ganglioside analogues containing modified a-L-fucopyranose residues. Reductive dethioacylation of 2-(trimethylsilyl)ethyl 3,4-di-O-benzoyl-2-O-(phenoxy)thiocarbonyl-P-L-fucopyranoside, prepared from L-fucose in eight steps, gave the 2-deoxy compound, which was transformed via selective removal of the 2-0rimethylsilyl)ethyl group, subsequent acetylation, and displacement of the 1-acetoxy group by a methylthio group, into methyl 3,4-di-O-benzoyl-2,6-dideoxy-l-thio-c@-L-Zyxohexopyranoside (11). 2-(Trimethylsilyl)ethyl 2,4-di-O-benzoyl-3-O-(phenoxy)thiocarbonyI$-L-fucopyranoside, prepared from the unsubstituted glycoside in four steps, and 2-(trimethylsilyl)ethyl 2,3-di-O-benzoyl-4-0-(phenoxy)thiocarbonyl-~-L-fucop~anoside,

similarly prepared in two steps, were transformed via reduction of the (phenoxy)thiocarbonyloxy group, selective removal of the 2-(trimethylsilyl)ethyl group, 0-acetylation, displacement of the l-acetoxy group by a methylthio group as described for 11, and finally replacement of the benzoyl groups by benzyl groups, into the analogous, protected methyl 3-and 4-deoxy-lthio$-L-fucopyranosides.