Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Chemistry. 2011 Dec 23;17(52):14922-8. doi: 10.1002/chem.201102375. Epub 2011 Nov 3.
A new class of chiral tridentate N-donor pincer ligands, bis(oxazolinylmethylidene)isoindolines (boxmi), was synthesized in three steps starting from readily available phthalimides. Their reaction with ethyl (triphenylphosphoranylidene)acetate by means of a key-step Wittig reaction gave the ligand backbones, which were condensed with amino alcohols and then cyclized to obtain the corresponding ligands. These ligands were subsequently applied in the nickel(II)-catalyzed enantioselective fluorination of oxindoles and β-ketoesters to obtain the corresponding products with enantioselectivities of up to >99% ee and high yields. Application of the chiral pincer ligands in the chromium-catalyzed enantioselective Nozaki-Hiyama-Kishi reaction of aldehydes gave the corresponding alcohols with an optimal enantioselectivity of 93%.
一类新型的手性三齿 N-供体钳形配体，双（恶唑啉基亚甲基）茚满（boxmi），可从易得的邻苯二甲酰亚胺出发，经三步反应合成。通过关键的 Wittig 反应，它们与乙基（三苯基膦亚甲基）乙酸酯反应，得到配体骨架，然后与氨基醇缩合，再环化得到相应的配体。这些配体随后应用于镍（II）催化的吲哚和β-酮酯的对映选择性氟化反应中，以获得对映选择性高达 >99%ee 和高收率的相应产物。手性钳形配体在铬催化的醛的不对称 Nozaki-Hiyama-Kishi 反应中的应用，得到了相应醇的最优对映选择性为 93%。
