The first family of sugar derivative dithioethers 1,2-O-isopropylidene-3,5-bis(methylsulfanyl)-, (+)-RiSSMe2, 1,2-O-isopropylidene-3,5-bis(isopropylsulfanyl)-, (+)-RiSSPri2, and 1,2-O-isopropylidene-3,5-bis(phenylsulfanyl)-α-D-(+)-ribofuranose, (+)-RiSSPh2, was prepared from 1,2-O-isopropylidene-3,5-di-O-trifluoromethanesulfonyl-D-xylofuranose. Reaction of these chiral C1 symmetrical dithioether ligands with [Ir(cod)2]BF4 (cod = 1,5-cyclooctadiene) yielded the iridium complexes [Ir(cod)(+)-RiSSR2}]BF4 1–3. Their reaction with H2 at 0 °C gave the cis-dihydridoiridium(III) complexes [IrH2(cod)(+)-RiSSR2}]BF4 4–6. Complexes 1–3 were tested in the asymmetric hydrogenation of acrylic acid derivatives at 1 bar of H2 and room temperature, providing enantioselectivities of up to 62%.
首个糖衍
生物二
硫醚家族——1,2-O-异丙叉-3,5-双(甲
硫基)-, (+)-RiSSMe2、1,2-O-异丙叉-3,5-双(异
丙硫基)-, (+)-RiS
SPri2 和 1,2-O-异丙叉-3,5-双(苯
硫基)-α-D-(+)-
呋喃核糖, (+)-RiS
SPh2, 由 1,2-O-异丙叉-3,5-双-O-三
氟甲磺酰基-D-木
呋喃糖制备而得。这些手性C1对称二
硫醚
配体与 [Ir(cod)2]BF4 (cod =
1,5-环辛二烯)反应生成
铱配合物 [Ir(cod)(+)-RiSSR2}]BF4 1-3. 它们在0°C下与H2反应,得到顺式二氢
铱(III)配合物 [IrH2(cod)(+)-RiSSR2}]BF4 4-6. 配合物1-3在1巴H2和室温下进行了
丙烯酸衍
生物的不对称氢化测试,最高实现了62%的立体选择性。