Stannylene Activation in Glycoside Synthesis: Regioselective Glycosidations at the Primary Position of Galactopyranosides Unprotected in the 2-, 3-, 4-, and 6-Positions
作者:Per J. Garegg、Jean-Luc Maloisel、Stefan Oscarson
DOI:10.1055/s-1995-3918
日期:1995.4
Stannylene activation with dibutyltin oxide of methyl D-galactopyranosides and of methyl β-D-glucopyranoside, respectively, followed by glycosidation with 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl bromide promoted by tetrabutylammonium iodide, or followed by glycosidation with ethyl 2,3,4,6-tetra-O-benzoyl-1-thio-β-D-glucopyranoside, or ethyl 2,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside, or ethyl 2,3,4,6-tetra-O-benzoyl-1-thio-α-D-mannopyranoside, the latter four glycosyl donors being promoted by dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST), led to regioselective glycosidation at the 6-OH of the stannylene glycosyl acceptors. This selectivity was not observed in the absence of stannylene activation.
分别用二丁基氧化
锡活化甲基 D-
吡喃半
乳糖苷和甲基 δ-
D-吡喃葡萄糖苷,然后用 2,3,4,6- O-四苄基-δ-
D-吡喃葡萄糖基
溴化物在
四丁基碘化铵的促进下进行糖化,或用乙基 2,3,4,6- O-四苯甲酰基-1-
硫代-δ-
D-吡喃葡萄糖苷进行糖化、或乙基 2,3,4,6-O-四乙酰基-2-脱氧-2-
酞酰亚胺基-1-
硫代-δ-
D-吡喃葡萄糖苷,或乙基 2,3,4,6-O-四苯甲酰基-1-
硫代-δ-D-
吡喃
甘露糖苷、在
三氟甲磺酸二甲基(甲
硫基)锍(
DMTST)的促进下,后四种糖基供体在链烯糖基受体的 6-OH 处发生了区域选择性糖苷化反应。在没有
锡烯活化的情况下,则观察不到这种选择性。