602
3
Chemical Glycosylation Reactions
⊡ Scheme 31
The pentasaccharide core of the protein membrane anchor of Trypanosoma brucei
makes use of the stereocontrolled glycosylation of inositol derivative 222 with 2-deoxy-2imino NPG 221 ( > Scheme 31b). Protecting group manipulations led to acceptor 223 that was
glycosylated with NPG 224, to furnish, after desilylation, the acceptor CDE block, 225. The
donor counterpart 220, had been readily prepared by Koenigs–Knorr [115] coupling of NPG
219 with glycosyl bromide 218 ( > Scheme 31a). Finally, coupling of fragments AB (220) and
CDE (225) promoted by NIS/TfOH led to pentasaccharide 226, in 73% as an α/β (2:3) mixture
( > Scheme 31c).
3
Chemical Glycosylation Reactions
⊡ Scheme 31
The pentasaccharide core of the protein membrane anchor of Trypanosoma brucei
makes use of the stereocontrolled glycosylation of inositol derivative 222 with 2-deoxy-2imino NPG 221 ( > Scheme 31b). Protecting group manipulations led to acceptor 223 that was
glycosylated with NPG 224, to furnish, after desilylation, the acceptor CDE block, 225. The
donor counterpart 220, had been readily prepared by Koenigs–Knorr [115] coupling of NPG
219 with glycosyl bromide 218 ( > Scheme 31a). Finally, coupling of fragments AB (220) and
CDE (225) promoted by NIS/TfOH led to pentasaccharide 226, in 73% as an α/β (2:3) mixture
( > Scheme 31c).