二茂铁配体在不对称烯丙基取代反应中的应用(英文)

Application of Chiral Ferrocene Ligands in Asymmetric Palladium Catalyzed Allylic Substitution Reactions

以恶唑啉为导向基团 ,通过邻位锂化方便地高非对映选择性地合成了一系列平面手性二茂铁硫恶唑啉、硒恶唑啉和膦恶唑啉配体 .应用于 1 ,3 二苯基烯丙基醋酸酯的烯丙基烷基化反应 ,ee值最高可达 99%,膦氮配体在烯丙基胺化反应中 ,ee值最高也可达 97%.此外 ,发现中心手性起到了决定产物ee值和绝对构型的作用 ,平面手性和中心手性的匹配在取得高对映选择性上是重要的 .设计合成的一类平面手性二茂铁修饰的手性口袋型双膦配体 ,由于有平面手性的辅助而具有更有效的诱导效应 .这类配体在前手性亲核试剂的不对称烯丙基化生成季碳氨基酸衍生物构及alpha 位双取代季碳酮反应中 ,ee值最高分别可达到 75 %和 95 %.设计合成的 1 ,1’ 二茂铁膦氮配体 ,在单取代的烯丙基醋酸酯的钯催化区域选择性及对映选择性的烯丙基烷基化及胺化反应中 ,显示了非常高的反应活性、区域选择性和对映选择性 .配体中BINOL羟基由于和苄胺存在分子间氢键而对反应的选择性起到了关键作用 。

Thioether, selenide and phosphino derivatives of ferrocenyl oxazolines, synthesized from ferrocenyl oxazolines, were found to be effective in palladium catalyzed allylic alkylation with up to 99% ee. With P, N ligand, palladium catalyzed allylic amination was achieved with 97% ee. The enantio control was dominated by the central chirality. However, the match between planar chirality and central chirality is critical for high enantioselectivity. A series of planar chiral ferrocene modified bisphosphine pocket ligands were synthesized and found to be very effective in construction of quaternary carbon centers using asymmetric allylic alkylation. Some non coded alpha, alpha disubstituted amino acids were obtained with up to 75% ee using ketone imino esters. Using enolate of simple ketone as nucleophile, alpha, alpha disubstituted ketones were obtained with up to 95% ee. A new type of ferrocene based P , N ligands has been synthesized and was found to be very effective in regio and enantio selective palladium catalyzed allylic alkylation and amination of mono substituted allylic acetates. The free OH in the ligand was very important for selective control by the hydrogen bonding with benzylamine in later reaction, which was proved by experimental results.