Nucleophilic Substitution of Hydrogen in Electron-Deficient Arenes

NUCLEOPHILIC SUBSTITUTION OF HYDROGEN IN ELECTRON-DEFICIENT ARENES 

Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland 

Conventional nucleophilic substitution of halogens and other nucleofugal groups X in electron-deficient arenes, particularly nitroarenes, proceeds via addition of nucleophiles at positions occupied by X to form o -adducts. The addition is coimected with dearomatization—thus, the adducts, which are in fact nitronate anions of nitro cyclohexadienes, undergo rapid rearomatization via spontaneous departure of X to form products of nucleophilic aromatic substitution (Sj Ar) reaction. Detailed discussion of these processes is presented in Chapter 6. 

Arene Chemistry Reaction Mechanisms and Methods for Aromatic Compounds, First Edition. Edited by Jacques Mortier. 

SCHEME 11.1 Relation of rates of nucleophilic addition at positions occupied by (a) chlorine and (b) hydrogen. 

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During the revision process of this chapter, we received a note from the editorial board concerning the Nucleophilic Substitution of Hydrogen in Electron-Deficient Arenes, where some mechanistic aspects significantly differ from the one addressed herein mainly in those issues related to the experimental conditions. We recommend the reader to consult Chapter 11 by Prof. Mieczyslaw M kosza for a deeper discussion about this important point. 

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