Regio- and Stereoselective Palladium-Pincer Complex Catalyzed Allylation of Sulfonylimines with Trifluoro(allyl)borates and Allylstannanes: A Combined Experimental and Theoretical Study
作者:Olov A. Wallner、Kálmán J. Szabó
DOI:10.1002/chem.200600406
日期:2006.9.6
employed as allylic precursors; however, the reaction with trifluoro(crotyl)borate results in poor stereoselectivity. The major diastereomer formed in these reactions was the syn isomer, while the (previously reported) reactions with aldehyde electrophiles afforded the anti products, indicating that the mechanism of the stereoselection is dependent on the applied electrophile. Therefore, we have studied
已经通过使用取代的三氟(烯丙基)硼酸酯和三甲基烯丙基锡烷来进行区域和立体选择性的钯-钳子络合物催化磺酰亚胺的烯丙基化。反应为相应的支链烯丙基产物提供了极好的区域选择性。当使用三氟(肉桂基)硼酸酯和三甲基肉桂基锡烷作为烯丙基前体时,这些方法的立体选择性很高。然而,与三氟(巴豆基)硼酸酯的反应导致差的立体选择性。在这些反应中形成的主要非对映异构体是顺式异构体,而与醛亲电试剂的反应(先前报道)提供了反产物,表明立体选择的机理取决于所施加的亲电试剂。所以,我们通过实验研究和DFT建模研究了烯丙基化反应的机理。实验机理研究清楚地表明,三氟(烯丙基)硼酸钾与钯-钳子配合物1a发生金属转移,从而得到eta(1)-烯丙基钯-钳子配合物(1 e)。在理论上以B3PW91 / LANL2DZ + P的水平通过DFT计算研究了烯丙基部分从钯向磺酰亚胺碱底物转移的机理。这些计算表明,磺酰亚胺的亲电取代是在一步法中