Enantioselective desymmetrization of meso-epoxides with anilines catalyzed by polymeric and monomeric Ti(IV) salen complexes
作者:Rukhsana I. Kureshy、Manish Kumar、Santosh Agrawal、Noor-Ul H. Khan、Balchand Dangi、Sayed H. R. Abdi、Hari C. Bajaj
DOI:10.1002/chir.20868
日期:2011.1
The active catalysts for the enantioselective ring opening (ARO) of meso‐stilbene oxide, cis‐butene oxide, cyclohexene oxide, cyclopentene oxide, and cyclooctene oxide with various substituted anilines were generated in situ by the reaction of Ti(OiPr)4 with poly‐[(R,R)‐N,N′‐bis‐3‐(1,1‐dimethylethyl)‐5‐methylene salicylidene} cyclohexane‐1,2‐diamine]‐1 and (1R,2R)‐N,N′‐bis[3,5‐di(tert‐butyl)salicylidene]
对的对映选择性开环(ARO),活性催化剂的内消旋-茋氧化物,顺式丁烯氧化物,环己烯氧化物,环戊烯氧化物,环辛烯和乙烷与由钛的反应在原位生成的各种取代的苯胺(O我PR)4带有聚[[(R,R)‐ N,N'-双‐ 3-(1,1-二甲基乙基)‐5‐亚甲基水杨基}环己烷‐1,2‐二胺] ‐1和(1 R,2 R)-N,N'-双[3,5-二(叔丁基)水杨基]环己烷-1,2-二胺-2。这些催化剂在非外消旋亚胺的存在作为添加剂提供的β氨基的优良率(99%)和手性纯度(对映体过量(醇EE为的ARO)高达99%)内消旋与苯胺芪氧化物。相同的方案对环氧化物的ARO无效。但是,当使用三苯膦作为添加剂时,环己烯氧化物ARO的催化剂性能有了显着提高(收率85-90%;ee 63-67%)。原位生成的聚合催化剂和单体催化剂都以相似的方式进行操作,不同之处在于,与单体催化剂Ti(IV)-相比,聚合催化剂Ti(IV)-1更