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Synthesis and conformational studies of calixarene analogue chiral [3.3.1]metacyclophanes
journal contributionposted on 07.09.2015, 10:29 by Md. Monarul Islam, Tomiyasu Hirotsugu, Pierre Thuery, Taisuke Matsumoto, Junji Tanaka, Mark Elsegood, Carl Redshaw, Takehiko Yamato
Trihydroxy[3.3.1]metacyclophane, which can be regarded as an unsymmetrical or incomplete "homocalixarene", has been prepared from rimethoxy[3.3.1]metacyclophane by demethylation with trimethylsilyl iodide in MeCN. Di-O-methylation at the lower rim of trihydroxy[3.3.1]metacyclophane in the presence of K2CO3 in acetone afforded a novel, inherently chiral calixarene-analogue, namely a macrocyclic [3.3.1]metacyclophane, possessing C1 symmetry. The inherent chirality of the two conformers was characterized by 1H NMR spectroscopy by addition of an excess of Pirkle's chiral shift reagent [(S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol], which caused a splitting of the OMe group and AB patterns corresponding to the methylene protons.