Treatment of alkyl D-glycopyranosides and alkyl or phenyl 1-thio-ß-D-glycopyranosides 1 with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane gave the corresponding 4,6-O-(1,1,3,3-tetraisopro-pyldisiloxane-1,3-diyl) protected glycosides 2 which were subsequently benzoylated with benzoyl bromide to give the fully blocked glycosides 3. Reaction of the latter with methyl pyruvate and a catalytic amount of trimethylsilyl trifluoromethanesulfonate gave alkyl and phenyl 4,6-O-[1-(methoxycarbonyl)ethylidene]glycopyranosides 4 with high diastereoselectivity.
烷基 D-
吡喃
葡糖苷和烷基或苯基1-
硫-ß-D-
吡喃
葡糖苷 1 与1,3-二
氯-1,1,3,3-四异丙基二
硅氧烷反应,得到相应的4,6-O-(1,1,3,3-四异丙基二
硅氧烷-1,3-二基)保护的糖苷 2,随后用
苯甲酰溴进行苯甲酰化,得到完全保护的糖苷 3。后者与
丙酮酸甲酯和少量三甲基
硅基
三氟甲磺酸酯反应,以高非对映选择性得到烷基和苯基4,6-O-[1-(甲氧羰基)乙叉]
吡喃
葡糖苷 4。