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Molecules 2018, 23(4), 750; https://doi.org/10.3390/molecules23040750

Economy of Catalyst Synthesis—Convenient Access to Libraries of Di- and Tetranaphtho Azepinium Compounds

1
Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
2
Institute of Organic Chemistry, University of Vienna, Währinger Straße 38, Wien 1090, Austria
3
Institute of Inorganic Chemistry, University of Vienna, Währinger Straße 42, Wien 1090, Austria
4
Institute of Chemical Catalysis, University of Vienna, Währinger Straße 38, Wien 1090, Austria
*
Author to whom correspondence should be addressed.
Academic Editors: Laura Palombi and Antonio Massa
Received: 22 February 2018 / Revised: 14 March 2018 / Accepted: 20 March 2018 / Published: 24 March 2018
(This article belongs to the Special Issue Enantioselective Catalysis)
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Abstract

Efficient optimization procedures in chiral catalysis are usually linked to a straightforward strategy to access groups of structurally similar catalysts required for fine-tuning. The ease of building up such ligand libraries can be increased when the structure-modifying step (introduction of a substituent) is done at a later stage of the synthesis. This is demonstrated for the extended family of di- and tetranaphtho azepinium compounds, widely used as chiral phase transfer catalysts (PTC). Using 2,6-diiodo-4,5-dihydro-3H-dinaphtho[2,1-c:1′,2′-e]azepine and 4,8-diiodo-6,7-dihydro-5H-dibenzo[c,e]azepine, respectively, as key intermediates, 18 spiro-azepinium compounds were synthesized in a total yield of 25–42% over 6–7 steps from 1,1′-binaphthyl-2,2′-dicarboxylic acid or diphenic acid, respectively. The replacement of iodo groups with aryl substituents was performed as the last or the penultimate step of the synthesis. View Full-Text
Keywords: 1,1′-binaphthyl; biphenyl; Suzuki-Miyaura coupling; phase transfer catalyst 1,1′-binaphthyl; biphenyl; Suzuki-Miyaura coupling; phase transfer catalyst
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Tharamak, S.; Knittl-Frank, C.; Manaprasertsak, A.; Pengsook, A.; Suchy, L.; Schuller, P.; Happl, B.; Roller, A.; Widhalm, M. Economy of Catalyst Synthesis—Convenient Access to Libraries of Di- and Tetranaphtho Azepinium Compounds. Molecules 2018, 23, 750.

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