甲苯通过氯化铑卟啉(Rh(por)Cl)进行碱促进的选择性苄基碳氢键活化(CHA)。在不存在亲核碱的情况下,形成了芳基和苄基铑卟啉。在亲核碱的存在下,苄基活化反应的选择性,速率和官能团相容性均得到增强。发现K 2 CO 3是获得最佳产率的最佳碱。K 2 CO 3存在下的邻,间和对位甲苯在无溶剂条件下和在苯溶剂中均以高收率得到了相应的铑卟啉苄基。从机理上讲,在不存在亲核碱的情况下,阳离子铑(III)卟啉物种与一些铑(II)卟啉物种是最有可能说明芳基和苄基CHA的中间体。在碱的存在下,Rh(por)OH是通过用Rh(por)Cl进行配体取代而生成的,并迅速还原,得到铑(II)卟啉二聚体和H 2 O 2。由1观察到,苄基CHA的关键铑卟啉中间体是铑(II)卟啉二聚体和氢化物。1 H NMR光谱,其进行平行的苄基CHA反应,其中铑(II)卟啉二聚体是反应性更高的中间体。
The porphyrin-stoppered rotaxane was prepared from dibenzo-24-crown-8 (DB24C8) and the secondary ammonium ion derivative end-capped by the axial coordination of rhodium(III) tetra-(3,5-di-tert-butylphenyl) porphyrin [TBPP Rh(III) Cl]. This rotaxane molecule was designed aiming at the immobilization on a substrate and the analysis of the physicochemical properties as a single molecule.
1H NMR analysis of porphyrin-stoppered rotaxanes: effect of the porphyrin substituents on the macrocycleElectronic supplementary information (ESI) available: chemical shift data. See http://www.rsc.org/suppdata/nj/b4/b403707c/
作者:Taichi Ikeda、Masumi Asakawa、Toshimi Shimizu
DOI:10.1039/b403707c
日期:——
shorter) and threeporphyrin rhodium chlorides having different substituents. The chemical shift changes in 1H NMR spectra, due to the anisotropic shielding effects by the aromatic rings, enabled us to estimate the molecular structure. In the cases of the rotaxanes with relatively shorter thread, the conformation of the macrocycle proved to be affected by the substituents in the terminal porphyrin. This result