Further Observations on Conformational and Substituent Effects in Acid-Catalyzed “3 + 1” Cyclizations of Tripyrranes with Aromatic Dialdehydes
作者:Timothy D. Lash、Katrina M. Bergman
DOI:10.1021/jo301945f
日期:2012.11.2
Tripyrranes with tert-butyl and phenyl substituents have been prepared and used to synthesize oxybenziporphyrins, oxypyriporphyrins, benzocarbaporphyrins, and azuliporphyrins with phenyl and tert-butyl substituents via a “3 + 1” methodology. The proton NMR spectra for the tripyrrane dibenzyl esters indicate that these tripyrrolic systems take on a helical conformation that favors macrocycle formation
已经制备了具有叔丁基和苯基取代基的三吡喃,并用于合成具有苯基和叔丁基的氧苯并卟啉,氧吡啶并卟啉,苯并碳杂卟啉和天青卟啉。-丁基取代基通过“ 3 + 1”方法。三吡喃二苄酯的质子NMR光谱表明,这些三吡咯体系呈螺旋构象,有利于大环的形成,而NMR数据可作为“ 3 +1”合成效率的有用预测指标。然而,事实证明四苯基三吡喃在通常的反应条件下易于酸解裂解,并且卟啉类产物的收率很低。通过在纯TFA中进行反应可以在一定程度上克服这个问题。这些取代基的存在导致新的卟啉类结构的光谱性质和变径特性发生重大变化。