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Cyclohexadienyl‐Type Cationic Intermediates in the Friedel–Crafts Alkylation of Benzene Derivatives with the 9‐Fluorenyl Cation—Observation by Laser Flash Photolysis
Author(s) -
Cozens Frances,
Li Jianhui,
McClelland Robert A.,
Steenken Steen
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199207431
Subject(s) - flash photolysis , cationic polymerization , chemistry , mesitylene , friedel–crafts reaction , photochemistry , electrophile , benzene , alkylation , electrophilic aromatic substitution , photodissociation , carbocation , medicinal chemistry , organic chemistry , reaction rate constant , catalysis , kinetics , physics , quantum mechanics
Direct detection of both types of cationic intermediates in an electrophilic aromatic substitution is possible by laser flash photolysis of 9‐fluorenol ( 1 ) in the presence of arenes like mesitylene ( 2 ). The reactions are fast, yet products are formed with selectivities suggestive of a transition state resembling the intermediate cyclohexadienyl cation (“σ complex”) and not a “π complex”.