title: Ring closure reactions of 2,6-diazaheptatrienyl metal compounds: synthesis of 3-aminoindole derivatives and 14-membered macrocyclic dimers.
abstract: 2,6-Diazaheptatrienyl metal compounds 6(-)K(+) are easily accessible from the corresponding diimines 6 by deprotonation using KO-t-Bu as base. According to quantum chemical calculations, they are, in comparison to other isomeric species with nitrogen atoms in other positions, highly reactive intermediates, which undergo in dilute solution at 50 °C ring closure reactions to form 3-aminoindole derivatives 8/10. In contrast, in more concentrated solution at room temperature, the formation of 14-membered macrocyclces 13 as a result of formal dimerization is observed. The 3-aminoindole derivatives obtained in this work possess rare substitution patterns, and the macrocyclic compounds are essentially unknown. Two-fold vinylogous derivatives 7 give rise to tricyclic systems with δ-carboline backbone 12. The experimental results are interpreted using high-level DFT calculations with regard to the possible reaction mechanism and the nature of the transition state of the five-membered ring formation. The molecular structures in the solid state of all types of compounds were elucidated by X-ray diffraction.
authors: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany.
authors: Benedikt
authors: B
authors: Neue
authors: Ralph
authors: R
authors: Reiermann
authors: Klaus
authors: K
authors: Gerdes
authors: Roland
authors: R
authors: Fröhlich
authors: Birgit
authors: B
authors: Wibbeling
authors: Ernst-Ulrich
authors: EU
authors: Würthwein