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Transition–Metal–Diene Complexes in Organic Synthesis, 12. Regio‐ and Stereoselectivity of Electrophilic Substitutions of Arylamines by Tricarbonyliron–Complexed Cyclohexadienylium Cations and Oxidative Cyclizations to Carbazoles
Author(s) -
Knölker Hans–Joachim,
Bauermeister Michael,
Pannek Jörn–Bernd
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921251226
Subject(s) - chemistry , substituent , electrophile , stereoselectivity , regioselectivity , alkylation , medicinal chemistry , ligand (biochemistry) , oxidative addition , stereochemistry , organic chemistry , catalysis , biochemistry , receptor
Electrophilic substitutions of donor–substituted arylamines using tricarbonyliron–complexed cyclohexadienylium cations lead regio‐ and stereoselectively to the corresponding tricarbonylcyclohexadieneiron complexes. The C–C bond formations occur regioselectively in the ortho position with respect to the amino group with arylamines containing a substituent in the para position. The initially formed N ‐alkylated arylamine (kinetic product) is shown to rearrange in an intermolecular process to the C ‐alkylated arylamine (thermodynamic product). The reported oxidative cyclization to 3–methylcarbazole yields large amounts of the demetalated ligand. However, oxidative cyclization to 3–methoxycarbazole is possible under mild reaction conditions (room temperature) by using especially activated manganese dioxides.