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Synthesis and conformational studies of calixarene analogue chiral [3.3.1]metacyclophanes
journal contributionposted on 07.09.2015 by Md. Monarul Islam, Tomiyasu Hirotsugu, Pierre Thuery, Taisuke Matsumoto, Junji Tanaka, Mark Elsegood, Carl Redshaw, Takehiko Yamato
Any type of content formally published in an academic journal, usually following a peer-review process.
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.