Special Issue Reviews and Accounts ARKIVOC 2009 (i) 63-80 Superelectrophiles in heterocyclic ring-forming reactions Douglas A. Klumpp Department of Chemistry and Biochemistry, Northern Illinois University DeKalb, IL 60115 E-mail: dklumpp@niu.edu Abstract Superelectrophiles are multiply charged cationic species which may exhibit remarkable reactivities towards weak nucleophiles. Since their discovery in the 1970s, many novel synthetic methodologies have been developed using superelectrophiles. In the following Account, superelectrophilic ring-forming reaction will be examined, specifically those reaction which produce heterocyclic systems. Keywords: Superelectrophiles, dications, superacids, heterocycles Table of Contents 1. Introduction 2. Ring-forming Reactions 2.1 Gitionic superelectrophiles 2.1.1 Gitionic superelectrophiles: geminal systems 2.1.2 Gitionic superelectrophiles: vicinal systems 2.1.3 Gitionic superelectrophiles: 1,3-dicationic systems 2.2 Distonic superelectrophiles 3. Summary 1. Introduction During the 1960s and 1970s, there were a number of reports describing electrophilic reactions in which the cationic electrophiles were notably more reactive in solutions of increasing acidities.1 These electrophiles were often capable of reacting with even the weakest nucleophiles, such as alkanes or deactivated arenes. This pattern of chemistry was first recognized by Olah with the proposed concept of superelectrophilic activation. As described in the early papers by the Olah group,1 superelectrophilic activation may occur when a cationic electrophile interacts with a ISSN 1551-7012 Page 63 ©ARKAT USA, Inc.
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