Synthesis of monodeoxy analogues of the trisaccharide alpha-D-Glcp-(1-->3)-alpha-D-Manp-(1-->2)-alpha-D-ManpOMe recognised by Calreticulin/Calnexin.
Six (3,4,4',6',3'' or 6'')-monodeoxy analogues of the title trisaccharide (1-6) have been prepared utilising monodeoxy monosaccharide precursors. The reducing end deoxy derivatives were synthesised by N-iodosuccinimide/silver trifluoromethanesulfonate (NIS/AgOTf)-promoted couplings of a common disaccharide thioglycoside donor 10 to suitably protected monodeoxy acceptors 9 and 12, affording trisaccharides, which after deprotection yielded target structures 1 and 2. The non-reducing end deoxy derivatives could similarly be produced by halide-assisted glycosylations of a common disaccharide acceptor 17 with monodeoxy glycosyl bromide donors (obtained from thioglycosides 18 and 20) to yield, after removal of protecting groups, target trisaccharides 3 and 4. The analogues with the deoxy function in the middle mannose residue, were obtained through orthogonal halide-assisted coupling of tetrabenzyl-glucopyranosyl bromide to monodeoxy thioglycoside acceptors to give thioglycoside disaccharides, which subsequently were used as donors in NIS/AgOTf-promoted couplings to a common 2-hydroxy-mannose acceptor 15 to afford trisaccharides; deprotection yielded the final target compounds 5 and 6.
Gemma
Emiliano
E
Department of Chemistry, Göteborg University, S-412 96 Gothenburg, Sweden.
Lahmann
Martina
M
Oscarson
Stefan
S
D037281:Calnexin / Q000378:metabolism*; D037282:Calreticulin / Q000378:metabolism*; D002240:Carbohydrate Sequence; D003837:Deoxy Sugars / Q000138:chemical synthesis*; D008969:Molecular Sequence Data; D014312:Trisaccharides / Q000138:chemical synthesis*
D037282:Calreticulin; D003837:Deoxy Sugars; D014312:Trisaccharides; D037281:Calnexin