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Stable Spirocyclic Meisenheimer Complexes
Department of Basic Sciences, King Saud Bin Abdulaziz University for Health Sciences-National, Riyadh, Central Province, Saudi Arabia
Departament de Química, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
* Authors to whom correspondence should be addressed.
Received: 15 May 2008; in revised form: 6 June 2008 / Accepted: 6 June 2008 / Published: 9 June 2008
Abstract: Meisenheimer complexes are important intermediates in Nucleophilic Aromatic Substitution Reactions (SNAr). They are formed by the addition of electron rich species to polynitro aromatic compounds or aromatic compounds with strong electron withdrawing groups. It is possible to distinguish two types of Meisenheimer or σ-complexes, the σHcomplex or σX-complex (also named ipso), depending on the aromatic ring position attacked by the nucleophile (a non-substituted or substituted one, respectively). Special examples of σX- or ipso-complexes are formed through intermediate spiro adducts, via intramolecular SNAr. Some of these spirocyclic Meisenheimer complexes, a type of σXcomplex, are exceptionally stable in solution and/or as solids. They can be isolated and characterized using X-ray, and various spectroscopic techniques such as NMR, UV-Vis, IR, and fluorescence. A few of these stable spirocyclic Meisenheimer complexes are zwitterionic and exhibit interesting photophysical and redox properties. We will review recent advances, synthesis and potential applications of these stable spirocyclic Meisenheimer complexes.
Keywords: Spirocyclic-; Zwitterionic-; Meisenheimer- Complexes; Fluorescent Compounts
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MDPI and ACS Style
Al-Kaysi, R.O.; Gallardo, I.; Guirado, G. Stable Spirocyclic Meisenheimer Complexes. Molecules 2008, 13, 1282-1302.
Al-Kaysi RO, Gallardo I, Guirado G. Stable Spirocyclic Meisenheimer Complexes. Molecules. 2008; 13(6):1282-1302.
Al-Kaysi, Rabih O.; Gallardo, Iluminada; Guirado, Gonzalo. 2008. "Stable Spirocyclic Meisenheimer Complexes." Molecules 13, no. 6: 1282-1302.