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
Boron trifluoride 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
三氟化硼或三甲基甲硅烷基三氟甲磺酸酯催化从 O-吡喃葡萄糖基或 O-吡喃半乳糖基三氯乙酰亚胺酯和硫醇生成硫糖苷,主要或仅产生 α-硫糖苷。然而,与作为催化剂的苯基二氟化硼的相同反应是高度β-选择性的。这些和以前的结果引发了酸/碱催化下的 SN2 型反应过程。