The native and epi-Cinchona alkaloids were reacted with (ArS)2/Bu3P in toluene at 65 °C to give the corresponding arylsulfanyl derivatives (15 examples, 31-75%) with complete inversion of configuration at 9-C stereogenic centers. Similar products were also obtained in the enantiospecific nucleophilic substitution of the 9-mesylates of alkaloids with sodium thiolates (4 examples, 73-84%) and no cinchona rearrangement was observed. The chiral thioethers obtained were preliminarily tested as N(sp3), S-donating chiral ligands in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenylprop-2-enyl acetate and gave the product with up to 78% ee.
fully characterized (X-ray, CD, 1H NMR-pattern). The chiral sulfoxides as well as the corresponding sulfides and sulfones were tested in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenyl-2-propenyl acetate. The sulfoxides obtained from Cinchona alkaloids bearing the additional stereogenic center gave the main product of configuration dependent on the chirality of alkaloid framework
苯基硫化物衍生自金鸡纳生物碱,9- PHS-外延-CD,9- PHS-外延QN,9- PHS-外延QD,和9-PHS-QN被氧化成相应的亚砜。无论使用何种氧化系统(NaIO 4,TEMPO / NaOCl,VO(acac)2 /手性席夫碱/ H 2 O 2),均观察到类似的氧化立体化学结果。亚砜的四个纯差向异构体9 PhSO-外延-CD和9- PhSO-外延QN分离和完全表征(X射线,CD,11 H NMR图谱)。在丙二酸二甲酯与外消旋-1,3-二苯基-2-丙烯基乙酸酯的钯催化的烯丙基烷基化反应中测试了手性亚砜以及相应的硫化物和砜。从带有另外的立体生成中心的金鸡纳生物碱获得的亚砜,其构型的主要产物仅取决于生物碱骨架的手性。与与相应的硫醚的反应相比,获得了相似的ee(高达60%),但产率却大大提高(90%)。结果是一致的与针对位于烯丙基碳的亲核攻击反式到在M形中间η硫原子3 π-烯丙基络合物。