Volume electrophilic reagents

This chapter summarizes those transannular reactions in medium ring carbocycles which result in carbon-carbon bond formation via alkylation of carbon, in the presence of electrophilic reagents. It is therefore a logical extension of two other chapters in this volume, covering Friedel-Crafts Alkylations (Chapter 1.8), and Polyene Cyclizations (Chapter 1.9). The discussion of these processes is organized according to the size of the cycloalkene from which transannular cyclization is effected. 

Derivatization Chemical reaction to improve separation or detection Treatment of active hydrogen functional group with electrophilic reagent Small volumes of reactive derivatization reagents... 

The volume concludes with the preparation of four useful starting materials. The highly electrophilic tricarbonyl reagent DIMETHYL MESOXALATE finds application as a two-electron component in various pericyclic processes. 9-BROMO-9-PHENYL-FLUORENE is becoming increasingly used for the protection of primary amines, particularly amino acids and amino esters. Two methods for introducing the 9-phenylfluorenyl group are illustrated in the preparations of (S)-N-(9-PHENYLFLUOREN-9-YL)ALANINE AND (S)-DIMETHYL N-(9-PHENYLFLUOREN-9-YL)ASPARTATE. 

Due to their configurational instability, asymmetric synthesis involving these reagents must usually be done with the aid of chiral auxiliaries that block one side of the nucleophilic carbon atom against electrophilic attack (passive volume) or fix the metal on one side by chelation (active volume)l9. 

Allylcopper/zinc reagents can be prepared directly by reaction of vinyl copper reagents with (iodomethyl)zinc iodide, the Simmons-Smith reagent. These allylcopper/zinc reagents do not couple with an alkyl iodide or benzyl bromide, but react readily with electrophiles such as aldehydes, ketones, or imines.3 This approach to organodimetallic reagents is apparently limited (see Iodomethylzinc iodide, this volume). 

The Lewis definitions of acid-base interactions are now over a half a century old. Nevertheless they are always useful and have broadened their meaning and applications, covering concepts such as bond-formation, central atom-ligand interactions, electrophilic-nucleophilic reagents, cationic-anionic reagents, charge transfer complex formation, donor-acceptor reactions, etc. In 1923 Lewis reviewed and extensively elaborated the theory of the electron-pair bond, which he had first proposed in 1916. In this small volume which had since become a classic, Lewis independently proposed both the proton and generalized solvent-system definitions of acids and bases. He wrote ... 

Baudoux J, Cahard D. Electrophilic fluorination with N-F reagents. In Organic Reactions. Volume 69.Hoboken, NJ Wiley 2007. p 347-672. 

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