Diversity-Oriented Synthesis of [2.2]Paracyclophane-derived Fused Imidazo[1,2-a]heterocycles by Groebke-Blackburn-Bienaymé Reaction: Accessing Cyclophanyl Imidazole Ligands Library |
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Authors: | Mareen Stahlberger Noah Schwarz Christoph Zippel Jens Hohmann Dr Martin Nieger Dr Zahid Hassan Prof Dr Stefan Bräse |
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Institution: | 1. Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany;2. Department of Chemistry, University of Helsinki, P. O. Box 55, 00014 University of Helsinki, Finland |
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Abstract: | This report describes the synthesis of a 2.2]paracyclophane-derived annulated 3-amino-imidazole ligand library through a Groebke-Blackburn-Bienaymé three-component reaction (GBB-3CR) approach employing formyl-cyclophanes in combination with diverse aliphatic and aromatic isocyanides and heteroaromatic amidines. The GBB-3CR process gives access to skeletally-diverse cyclophanyl imidazole ligands, namely 3-amino-imidazo1,2-a]pyridines and imidazo1,2-a]pyrazines. Additionally, a one-pot protocol for the GBB-3CR by an in situ generation of cyclophanyl isocyanide is demonstrated. The products were analyzed by detailed spectroscopic techniques, and the cyclophanyl imidazo1,2-a]pyridine was confirmed unambiguously by single-crystal X-Ray crystallography. The cyclophanyl imidazole ligands can be readily transformed to showcase their useful utility in preparing N,C-palladacycles through regioselective ortho-palladation. |
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Keywords: | Fused-imidazoles Groebke-Blackburn-Bienaymé (GBB) reaction Isocyanide Chemistry Multicomponent reactions [2 2]Paracyclophane |
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