Highly Enantioselective Ruthenium/PNNP-Catalyzed Imine Aziridination: Evidence of Carbene Transfer from a Diazoester Complex
作者:Joël Egloff、Marco Ranocchiari、Amata Schira、Christoph Schotes、Antonio Mezzetti
DOI:10.1021/om400735p
日期:2013.8.26
asymmetric aziridination. Aziridine yields were overall moderate to low (up to 33% isolated yield of the cis isomer) because of the competitive formation of diethyl maleate (7). The scope of the catalyst was studied with p- and m-substituted imines. NMR spectroscopic studies with 13C- and 15N-labeled EDA indicate that aziridine 6a is formed by carbene transfer from an EDA complex, [RuCl(EDA)(PNNP)]PF6
钌/ PNNP络合物将[RuCl(ET 2 O)(PNNP)] Y(Y = PF 6,4 PF 6 ; BF 4,4 BF 4 ;或的SbF 6,4的SbF 6)(10摩尔%)催化的对映选择性用重氮乙酸乙酯(EDA)作为卡宾源(PNNP =(1 S,2 S)-N,N'-双[邻-(二苯基膦基)亚苄基]环己烷-1,2-二胺)亚胺叠氮化。与得到最高的对映体选择性4的SbF 6,其aziridinated Ñ-亚苄基-1,1-二苯基甲胺(图5a),以顺式-乙基1-二苯甲基-3- phenylaziridine -2-羧酸乙酯(顺式- 6A)与93%的ee值在0℃下。据我们所知,这是过渡金属催化的不对称叠氮化中有史以来最高的对映选择性。由于马来酸二乙酯的竞争性形成,氮丙啶的总收率总体中等至低(顺式异构体的分离收率高达33%)(7)。催化剂的范围进行了研究与p -和中号取代亚胺。用13 C和15 N标