Synthesis of 2,3-dihydroindoles, indoles, and anilines by transition metal-free amination of aryl chlorides.
Aliphatic and aromatic amines react with 2- and 3-chlorostyrene in the presence of potassium tert-butoxide to give N-substituted 2,3-dihydroindoles in good yields. The combination of this domino-amination protocol with a suitable dehydrogenation reaction gives access to pharmacologically interesting indoles in a one-pot procedure. Overall product yields of N-substituted indoles >50% are obtained by this method starting from commercially available substrates. In addition to the intramolecular base-promoted amination of aromatic C-Cl bonds, metal-free intermolecular aminations of aryl chlorides with primary and secondary amines are described. The use of potassium tert-butoxide as base allows the synthesis of various anilines in good to excellent yields. Due to the formation of aryne intermediates, either N-substituted anilines or meta-substituted anilines are produced with excellent selectivities.
Beller
M
M
Institut für Organische Katalyseforschung an der Universität Rostock e. V., Buchbinderstrasse 5-6, 18055 Rostock, Germany. Matthias.Beller@ifok.uni-rostock.de
Breindl
C
C
Riermeier
T H
TH
Tillack
A
A