The novel branched oligosilyltriflates of formula [TfO(Me3Si)2Si]2E (2aâd)
[E = 0 (2a), SiMe2
(2b), GeMe2
(2c), SiMe2âSiMe2
(2d)] and [TfO(Me3Si)2SiSiMe2]3SiMe (9) have been prepared by the protodesilylation of [Ph(Me3Si)2Si]2E (1aâc), [H(Me3Si)2Si]2E (5d) and [Ph(Me3Si)2SiSiMe2]3SiMe (8) using TfOH (CF3SO3H) as reagent in almost quantitative yields. The crystal structure of 2b is reported.
Twisting the silicon backbone conformation in oxygen containing oligosilanes towards dihedral angles of 120â130° either by intramolecular hydrogen bonding or incorporation into a covalently bonded ring system effectively extends the delocalization of electrons in these Ïân mixed conjugated systems.
Novel silylated diols and polyols were prepared using a recently developed synthesis route with bifunctionalized silyl triflates. These silyl derivatives include two triflate functions, which allow a selective protection of two hydroxygroups. Moreover, the conformation of the silyl chain in the silane backbone led to exceptional UV properties.
are described. Some new silylating reagents (oligosilyl bistriflates), which were generated in situ from readily available phenylsilanes, resulted in 5,6-O-(glucofuranose) and 4,5-0-bridged (fructopyranose) carbohydrates with favoured seven- and eight-membered rings. In these cyclic oligosilyl diethers, three and four ring atoms, respectively, are Si atoms. It is noteworthy, that the seven-membered ring
描述了使用庞大的低聚甲硅烷基团的 1,2-O-异丙叉基-α-D-呋喃葡萄糖和 1,2-0-异丙叉叉基-β-D-吡喃果糖的区域选择性一锅 O-甲硅烷基化反应。一些新的甲硅烷基化试剂(低聚甲硅烷基双三氟甲磺酸酯)由现成的苯基硅烷原位生成,可生成 5,6-O-(呋喃葡萄糖)和 4,5-0-桥接(吡喃果糖)碳水化合物,具有受欢迎的七元和八元戒指。在这些环状低聚甲硅烷基二醚中,三个和四个环原子分别是Si原子。值得注意的是,5,6-O-[2,4-bis(trimethylsilyl)-1,1,1,3,3,5,5,5-octamethylpentasilan-2,4-diyl 的七元环]-1,2-O-异亚丙基-aD-呋喃葡萄糖通过将空气氧区域选择性插入到Si-Si键之一中而扩展为八元环。介绍了一些衍生物的 X 射线分析。