A facile synthesis of 1′-C-alkyl-α-disaccharides from 1-C-alkyl-hexopyranoses and methyl 1-C-methyl-hexopyranosides
摘要:
Direct O-glycosidations using the 1-C-alkyl-2,3,4,6-tetra-O-benzyl-hexopyranoses as the glycosyl donors were carried out with a catalytic amount (0.2 equiv.) of trimethylsilyl trifluoromethanesulfonate (TMSOTf). The glycosidations proceeded alpha -stereoselectively and furnished the corresponding 1'-C-alkyl-alpha -disaccharides in 71-90% yields. The O-transglycosidations from the benzylated and acetylated methyl I-C-methyl-or-hexopyranosides to the corresponding 1'-C-methyl-alpha -O-disaccharides were also examined, respectively. These transglycosidations took place on alpha -stereoselectivity and provided the 1'-C-methyl-alpha -O-disaccharides as the sole products, implying that no neighboring group participation occured in the reactions. (C) 2001 Elsevier Science Ltd. All rights reserved.
A facile synthesis of 1′-C-alkyl-α-disaccharides from 1-C-alkyl-hexopyranoses and methyl 1-C-methyl-hexopyranosides
摘要:
Direct O-glycosidations using the 1-C-alkyl-2,3,4,6-tetra-O-benzyl-hexopyranoses as the glycosyl donors were carried out with a catalytic amount (0.2 equiv.) of trimethylsilyl trifluoromethanesulfonate (TMSOTf). The glycosidations proceeded alpha -stereoselectively and furnished the corresponding 1'-C-alkyl-alpha -disaccharides in 71-90% yields. The O-transglycosidations from the benzylated and acetylated methyl I-C-methyl-or-hexopyranosides to the corresponding 1'-C-methyl-alpha -O-disaccharides were also examined, respectively. These transglycosidations took place on alpha -stereoselectivity and provided the 1'-C-methyl-alpha -O-disaccharides as the sole products, implying that no neighboring group participation occured in the reactions. (C) 2001 Elsevier Science Ltd. All rights reserved.
Stereoselective Glycosylation of <i>exo</i>-Glycals Accelerated by Ferrier-Type Rearrangement
作者:Hui-Chang Lin、Wen-Bin Yang、Yu-Feng Gu、Chen、Chung-Yi Wu、Chun-Hung Lin
DOI:10.1021/ol034130z
日期:2003.4.1
[GRAPHIC]Owing to the driving force of the Ferrier-type rearrangement, the exo-glycals are highly reactive with various alcohols to afford glycosides and glycoconjugates with exclusive alpha-configuration. The resulting vinyl group in these glycosylation products can be further elaborated for general applications, including the synthesis of spiro derivatives and glycosylation of 2-ketoaldonic acids.
A facile synthesis of 1′-C-alkyl-α-disaccharides from 1-C-alkyl-hexopyranoses and methyl 1-C-methyl-hexopyranosides
Direct O-glycosidations using the 1-C-alkyl-2,3,4,6-tetra-O-benzyl-hexopyranoses as the glycosyl donors were carried out with a catalytic amount (0.2 equiv.) of trimethylsilyl trifluoromethanesulfonate (TMSOTf). The glycosidations proceeded alpha -stereoselectively and furnished the corresponding 1'-C-alkyl-alpha -disaccharides in 71-90% yields. The O-transglycosidations from the benzylated and acetylated methyl I-C-methyl-or-hexopyranosides to the corresponding 1'-C-methyl-alpha -O-disaccharides were also examined, respectively. These transglycosidations took place on alpha -stereoselectivity and provided the 1'-C-methyl-alpha -O-disaccharides as the sole products, implying that no neighboring group participation occured in the reactions. (C) 2001 Elsevier Science Ltd. All rights reserved.