Synthesis of a cyanoethylidene derivative of 3,6-anhydro-d-galactose and its application as glycosyl donor.
Starting from 1,2,4-tri-O-acetyl-3,6-anhydro-alpha-d-galactopyranose, 4-O-acetyl-3,6-anhydro-1,2-O-(1-cyanoethylidene)-alpha-d-galactopyranose (7) was synthesized by treatment with cyanotrimethylsilane. Additionally, 3,4-di-O-acetyl-1,2-O-(1-cyanoethylidene)-6-O-tosyl-alpha-d-galactopyranose was prepared from the corresponding bromide and both cyanoethylidene derivatives were used as donors in glycosylation reactions. The coupling with benzyl 2,4,6-tri-O-acetyl-3-O-trityl-beta-d-galactopyranoside provided exclusively the beta-linked disaccharides in approximately 30% yield. The more reactive methyl 2,3-O-isopropylidene-4-O-trityl-alpha-l-rhamnopyranoside gave with donors 3 and 7 the corresponding disaccharides in nearly 60% yield. Furthermore, the synthesis of 3,6-anhydro-4-O-trityl-1,2-O-[1-(endo-cyano)ethylidene]-alpha-d-galactopyranose, which can be used as a monomer for polycondensation reaction is described.
Vogel
Christian
C
University of Rostock, Institute of Chemistry, Albert-Einstein-Str. 3a, D-18059 Rostock, Germany. Christian.vogel@uni-rostock.de
Torres
Galina Morales
GM
Reinke
Helmut
H
Michalik
Dirk
D
Voss
Alice
A
D003486:Cyanides / Q000138:chemical synthesis*; D004187:Disaccharides / Q000138:chemical synthesis; D005690:Galactose / Q000031:analogs & derivatives* / Q000737:chemistry; D006031:Glycosylation
D003486:Cyanides; D004187:Disaccharides; C117625:3,6-anhydrogalactose; D005690:Galactose