O-Glycosyl Donors
3.4
631
⊡ Scheme 63
Synthesis of hexasaccharide 383 based on DISAL donors
⊡ Figure 6
Glucosamine-derived DISAL donors
lower selectivities with primary hydroxyl acceptors (α/β ratio, from 1:1 to 1:7). A secondary
hydroxyl acceptor was glycosylated with N-Troc DISAL donor 389 under microwave heating
(130 °C, CH 3 NO 2 , LiClO 4 ) to give the corresponding disaccharide in 38% yield (β-anomer
only). N-TFAc DISAL donor 388 gave even lower yields on coupling reactions with primary
hydroxyl acceptors (35–45%) although β-disaccharides were obtained exclusively.
3.4
631
⊡ Scheme 63
Synthesis of hexasaccharide 383 based on DISAL donors
⊡ Figure 6
Glucosamine-derived DISAL donors
lower selectivities with primary hydroxyl acceptors (α/β ratio, from 1:1 to 1:7). A secondary
hydroxyl acceptor was glycosylated with N-Troc DISAL donor 389 under microwave heating
(130 °C, CH 3 NO 2 , LiClO 4 ) to give the corresponding disaccharide in 38% yield (β-anomer
only). N-TFAc DISAL donor 388 gave even lower yields on coupling reactions with primary
hydroxyl acceptors (35–45%) although β-disaccharides were obtained exclusively.