Stereoselective (2-naphthyl)methylation of sugar hydroxyls by the hydrogenolysis of diastereoisomeric dioxolane-type (2-naphthyl)methylene acetals
作者:Anikó Borbás、Zoltán B. Szabó、László Szilágyi、Attila Bényei、András Lipták
DOI:10.1016/s0008-6215(02)00180-5
日期:2002.11
reacted with 2-naphthaldehyde dimethyl acetal to diastereomeric dioxolane-type 2,3-O-(2-naphthyl)methylene or 3,4-O-(2-naphthyl)methylene acetals. The glycosides yielded the exo- and endo-isomers in nearly 1:1 ratio, 1,6-anhydro-beta-D-mannopyranose gave predominantly the endo-, and 1,6-anhydro-beta-D-galactopyranose exclusively endo-isomer. The acetals and some of their fully protected derivatives bearing
甲基α-L-和乙基1-硫代α-L-鼠李吡喃糖苷,1,6-脱水β-D-甘露吡喃糖和1,6-脱水β-D-吡喃吡喃糖的顺式/赤道OH基为与2-萘醛二甲基乙缩醛反应生成非对映体二氧戊环型2,3-O-(2-萘基)亚甲基或3,4-O-(2-萘基)亚甲基乙缩醛。配糖体以接近1:1的比例产生外向异构体和内向异构体,1,6-脱水β-D-甘露吡喃糖主要提供内向异构体,而1,6-脱水β-D-吡喃半乳糖仅内向异构体。用AlH(3)(3LiAlH(4)-AlCl(3))或Me(3)N.BH(3)-AlCl(3)缩醛化缩醛及其某些带有苄基或叔丁基二甲基甲硅烷基的完全保护的衍生物)试剂。两种试剂均裂解内消旋异构体,得到轴向NAP醚,吡喃糖苷的外消旋异构体提供了赤道NAP醚。