【作者】 王莉；

【导师】 黄跟平；

【作者基本信息】 天津大学 ， 化学， 2018， 硕士

【摘要】 过渡金属催化的环加成反应是构建碳环和杂环化合物最为重要的方法之一。本论文使用密度泛函理论计算对铑催化乙烯基氮杂环丙烷与联烯分子间[3+2]环加成反应进行机理研究,该反应能够用于合成生物上和医药上相关的手性亚甲基吡咯烷类化合物。理论计算结果表明该反应首先进行C-N键氧化加成步骤得到Rh-烯丙基中间体。随后,联烯近端C=C键迁移插入到Rh-N键/C(sp~2)-C(sp~3)还原消除或者联烯远端C=C键迁移插入到Rh-C键,分别形成3-亚甲基-吡咯烷产物和2-亚甲基-吡咯烷产物。本论文通过理论计算很好地再现了实验上观测到的高区域选择性、高E/Z选择性和高非对映立体选择性。理论计算发现取代基控制近端/远端选择性主要是由于取代基对联烯近端C=C键迁移插入Rh-N键步骤的重要影响。计算表明,对于与N-联烯胺的反应,由于胺取代基上N原子的孤电子对能够很好地稳定正电荷,可以显著地促进联烯近端C=C键迁移插入Rh-N键,最终形成产物3-亚甲基-吡咯烷。然而,对于普通联烯参与的反应,由于没有这种稳定的作用,联烯近端C=C键迁移插入Rh-N键这条路径所需活化能较高,反应更倾向于联烯远端C=C键迁移插入Rh-C键这一路径,从而反应选择性地得到产物2-亚甲基-吡咯烷。最后,高E/Z选择性和高非对映立体选择性可以通过联烯与Rh-烯丙基部分之间的空间排斥来解释。本论文的研究结果将为一系列类似反应的理解提供理论指导。更多还原

【Abstract】 The transition metal-catalyzed cycloadditions provide one of the most important protocles for the systhesis of carbo-and heterocycles.In this thesis,the rhodium-catalyzed intermolecular[3+2]cycloadditions of vinylaziridines with allenes were investigated by means of density functional theory(DFT)calculations,which represent an efficient method for the synthesis of biologically and pharmaceutically relevant chiral methylene pyrrolidines.The computations show that the Rh-allyl complex was formed through an initial C-N oxidative addition.The subsequent proximal C=C bond insertion of allene into the Rh-N bond/C(sp~2)-C(sp~3)reductive elimination or the distal-insertion of allene into the Rh-C bond led to the formation of 3-methylene-pyrrolidine products or 2-methylene-pyrrolidine products,respectively.The calculations reproduced well the experimentally observed high regio-,E/Z,and diastereo-selectivity.In particular,the substituent-controlled proximal/distal selectivity is mainly due to the significant impact of the substituent on the proximal-insertion of allene into the Rh-N bond.The calculations show that for the reactions with N-alleneamines,the proximal-insertion of allene into the Rh-N bond can be significantly promoted by the amine substituent because of the stabilization effect of the lone electron pair of the N atom on the developing positive charge,leading to the 3-methylene-pyrrolidine products.On the other hand for the reactions with general allenes,without such an effect the proximal-insertion of allene into the Rh-N bond is less favorable than the distal-insertion of allene into the Rh-C bond,which thus enables the selectivity switch to form the 2-methylene-pyrrolidine products.Finally,the high E/Z and diastereo-selectivity is rationalized in terms of the steric repulsion between the allene and the Rh-allyl moiety in the corresponding transition states.The results will provide important implications for a better understanding of related reactions.更多还原