Asymmetric Diels-Alder reactions catalyzed by chiral lanthanide(III) trifluoromethanesulfonates. Unique structure of the triflate and stereoselective synthesis of both enantiomers using a single chiral source and a choice of achiral ligands
作者:Shū Kobayashi、Haruro Ishitani、Iwao Hachiya、Mitsuharu Araki
DOI:10.1016/s0040-4020(01)85657-x
日期:——
were stereoselectively prepared by using a single chiral source, R-(+)-binaphthol, and a choice of achiral ligands. When 3-acetyl-1,3-oxazolidin-2-one was combined with the original catalyst system consisting of lanthanide triflate, R-(+)-binaphthol, and cis-1,2,6-trimethylpiperidine, a new catalyst was generated (catalyst A). In the presence of this catalyst, 3-acyl-1,3-oxazolidin-2-ones reacted with
开发了手性镧系三氟甲烷磺酸盐(三氟甲磺酸盐),并揭示了三氟甲磺酸盐的独特结构。在催化量的三氟甲磺酸酯存在下,酰基1,3-恶唑烷-2-酮与环戊二烯反应,以高收率和高对映体过量得到狄尔斯-阿尔德加合物。根据反应,通过使用单一手性来源,R-(+)-联萘酚和选择的非手性配体,立体选择性地制备了Diels-Alder加合物的两种对映体。当3-乙酰基-1,3-恶唑烷-2-酮与由三氟甲磺酸镧系元素,R-(+)-联萘酚和顺式1,2,6-三甲基哌啶组成的原始催化剂体系结合使用时,产生了一种新的催化剂(催化剂A)。在这种催化剂3-酰基-1的存在下,3-恶唑烷-2-酮与环戊二烯反应,以过量的对映体形式提供内加合物。产品的绝对配置为2S,3R。另一方面,当将3-苯基乙酰丙酮(PAA)与原始催化剂体系(催化剂B)混合时,观察到对映体的选择性,并以过量的对映体获得了具有绝对构型2R,3S的内加合物。