Reversal of Anomeric Selectivity with O-Glycosyl Trichloroacetimidates as Glycosyl Donors and Thiols as Acceptors Under Acid/Base Catalysis
作者:Amit Kumar、Richard R. Schmidt
DOI:10.1002/ejoc.201200138
日期:2012.5
Borontrifluoride or trimethylsilyl trifluoromethanesulfonate catalysed the generation of thioglycosides from O-glucopyranosyl or O-galactopyranosyl trichloroacetimidates and thiols giving mainly or exclusively α-thioglycosides. However, the same reactions with phenylboron difluoride as catalyst are highly β-selective. An SN2-type reaction course under acid/base catalysis is invoked by these and previous