Jiao Wenhua, Lash Timothy D
Department of Chemistry, Illinois State University, Normal 61790-4160, USA.
J Org Chem. 2003 May 16;68(10):3896-901. doi: 10.1021/jo0207628.
The MacDonald "3 + 1" route for porphyrinoid synthesis involves the acid-catalyzed condensation of tripyrranes with monocyclic dialdehydes, followed by an oxidation step. In the present study, yields were found to be greatly diminished when tert-butyl substituents were introduced on to the tripyrrane unit. Analysis of the proton NMR spectra for the tripyrranes indicates that the preferred conformation in solution has been radically altered by the presence of these tert-butyl moieties. This appears to be the first time that the NMR properties of an intermediate in porphyrin or porphyrin analogue synthesis have been correlated to its effectiveness in macrocycle formation.
麦克唐纳用于卟啉类化合物合成的“3 + 1”路线涉及三吡咯与单环二醛的酸催化缩合反应，随后是氧化步骤。在本研究中，发现当在三吡咯单元上引入叔丁基取代基时，产率会大幅降低。对三吡咯的质子核磁共振谱的分析表明，溶液中的优势构象已因这些叔丁基部分的存在而发生了根本改变。这似乎是首次将卟啉或卟啉类似物合成中间体的核磁共振性质与其在大环形成中的有效性相关联。
