Aryl and Allyl C-Glycosidation Methods Using Unprotected Sugars
摘要:
Practical and highly stereoselective aryl and allyl C-glycosidation methods using unprotected sugars as glycosyl donors have been developed. Aryl C-glycosidations of several unprotected 2-deoxy sugars with phenol and naphthol derivatives by the combined use of trimethylsilyl trifluoromethanesulfonate (TMSOTf)-AgClO4 or TMSOTf exclusively gave the corresponding unprotected o-hydroxyaryl beta-C-glycosides which appear in many biologically attractive aryl C-glycoside antibiotics as the key subunit. On the other hand, allyl C-glycosidations of several unprotected glycals with allyltrimethylsilane by TMSOTf afforded the corresponding unprotected and 2,3-unsaturated allyl alpha-C-glycosides in high yields which are versatile synthetic intermediates for the syntheses of optically active natural products.
Relative Reactivities of Aminoglycosides and their Synthetic Equivalents in the C-Glycosylation of Aromatics. Synthesis of the Pseudoaglycone (d-C-Glycoside) of the Benzanthrins
作者:Kathlyn A. Parker、Qing-jie Ding
DOI:10.1016/s0040-4020(00)00868-1
日期:2000.12
benzanthrin antibiotics was prepared by a short sequence in which C-glycosylation of dehydrorabelomycin dimethyl ether served as the key step. The use of a 3-azido 2,3,6-trideoxy pyranose as an activated equivalent of a 3-dimethylamino 2,3,6-trideoxy sugar was demonstrated in this reaction.
Highly regio- and stereo-selective C-arylglycosylations of the protected free sugars 1–4, the unprotected methyl glycosides 6–9 and the unprotected free sugars 10 and 11 with 2-naphthol 5 are effectively realized by the combined use of TMSOTf–AgClO4(TMSOTf = trimethylsilyloxytrifluoromethanesulfonate) as a catalytic activator.
Efficient C-arylglycosylation of 1-O-methyl sugar by novel use of TMSOTf-AgClO4 catalyst system
作者:Kazunobu Toshima、Goh Matsuo、Kuniaki Tatsuta
DOI:10.1016/0040-4039(92)88170-a
日期:1992.4
Highly beta-stereoselective C-arylglycosylations of the 1-O-methyl sugars 1 approximately 4 with 2-naphthol (9) were effectively achieved by novel combinational use of a catalytic amount of TMSOTf-AgClO4 as an activator. Also, C-arylglycosylations of the 1-O-acetyl sugars 5 approximately 8 with 9 in this way worked as well.