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Synthesis of upper rim-double-bridged calix[4]arenes bearing seven membered rings and related compounds†
M. Tlustý,V. Eigner,M. Babor,M. Kohout,P. Lhoták
RSC Advances Pub Date : 07/16/2019 00:00:00 , DOI:10.1039/C9RA05075B
Abstract

Meta/meta- and meta/para-disubstituted organomercury calix[4]arenes in the cone conformation were transformed into corresponding amino derivatives. Acylation and subsequent intramolecular cyclization using the Bischler–Napieralski reaction provided, in the case of the meta/meta-series, double bridged calixarenes possessing seven membered rings on the upper rim. A similar synthetic strategy applied to meta/para-isomers allowed for the isolation of monobridged compounds bearing an additional trifluoroacetamido group located distally to seven-membered rings. Both series represent inherently chiral systems, which were successfully resolved using preparative chiral HPLC. The pure enantiomers exhibited a recognition ability towards selected chiral guest molecules as documented by the 1H NMR titration experiments. The absolute configuration of the phenyl-substituted enantiomer (meta/meta-) was confirmed by single crystal structure determination (X-ray).

Graphical abstract: Synthesis of upper rim-double-bridged calix[4]arenes bearing seven membered rings and related compounds
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