DOI: 10.1002/chem.200601765 Intramolecular Hydroamination with Homogeneous Zinc Catalysts: Evaluation of Substituent Effects in N,N’-Disubstituted Aminotroponiminate Zinc Complexes Maximilian Dochnahl, [b] Karolin Lçhnwitz, [a] Jens-Wolfgang Pissarek, [b] Mustafa Biyikal, [b] Sabrina R. Schulz, [b] Sebastian Schçn, [b] Nils Meyer, [a] PeterW. Roesky,* [a] and Siegfried Blechert* [b] Introduction Aminotroponimines (ATIHs) are a well-known class of li- gands that were discovered in 1960s. [1] Early studies demon- strated that these interesting molecules display a very rich coordination chemistry. Thus a large number of main-group and transition-metal complexes have been synthesized. [2] ATI ligands behave as anionic bidentate nitrogen donors and form very stable chelate complexes. Although the imine and amine C À N bonds in the neutral ATIH ligand have dif- ferent bond lengths, the anionic ligand usually shows perfect C 2 symmetry, indicating a delocalization of the negative charge through the seven-membered ring (Scheme 1). [3] The synthesis of nitrogen-containing molecules is of great interest for academic and industrial researchers as a large number of natural products and pharmaceuticals contain amine or amide moieties. [4] Currently, these compounds are prepared in multistep reactions leading to substantial num- bers of byproducts and waste. Thus, hydroamination, the direct addition of an N ÀH bond to a C ÀC multiple bond is potentially an economically and environmentally superior process (Scheme 2). [5] A number of catalysts have been used in this reaction based mainly on lithium, [6] Group 4 metals, [7] the lanthanides, [8–10] the platinum metals, [11] and more recent- ly on calcium, [12] copper, [13] silver, [14] and gold. [15] Early tran- sition metals offer the advantage of being highly effective Abstract: A series of symmetrical and unsymmetrical N,N’-disubstituted ami- notroponimines (ATIHs) have been prepared. Substituents ranging from linear to cyclic alkyl groups, chelating ethers, and aryl groups were employed. The corresponding aminotroponimi- nate zinc complexes were then synthe- sized and characterized by a number of techniques, including by X-ray crystal- lography. Herein we report on the in- vestigations into their activity in the in- tramolecular hydroamination of nonac- tivated alkenes. We also demonstrate that complexes bearing ligands with cyclic alkyl groups show superior activ- ity in a number of selected reactions with functionalized aminoalkenes. Keywords: heterocycles · homoge- neous catalysis · hydroamination · substituent effects · zinc [a] Dipl.-Chem. K. Lçhnwitz, Dipl.-Chem. N. Meyer, Prof. Dr. P. W. Roesky Institut für Chemie und Biochemie, Freie Universität Berlin Fabeckstrasse 34-36, 14195 Berlin (Germany) Fax: (+ 49) 83-85-24-40 E-mail: roesky@chemie.fu-berlin.de [b] Dr. M. Dochnahl, Dipl.-Chem. J.-W. Pissarek, Dipl.-Chem. M. Biyikal, Dipl.-Chem. S. R. Schulz, S. Schçn, Prof. Dr. S. Blechert Institut für Chemie, Technische Universität Berlin Strasse des 17 Juni 115, 10623 Berlin (Germany) Fax: (+ 49) 30-31-42-36-19 E-mail: blechert@chem.tu-berlin.de Supporting information for this article is available on the WWW under http://www.chemistry.org or from the author. Scheme 1. Aminotroponiminates as anionic bidentate ligands. Scheme 2. Intramolecular hydroamination of alkenes. # 2007 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim Chem. Eur. J. 2007, 13, 6654 – 6666 6654