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Synthesis and conformational studies of chiral macrocyclic [1.1.1]metacyclophanes containing benzofuran rings

Islam, Md Monarul; Tomiyasu, Hirotsugu; Matsumoto, Taisuke; Tanaka, Junji; Rahman, Shofiur; Georghiou, Paris E.; Redshaw, Carl; Yamato, Takehiko

Authors

Md Monarul Islam

Hirotsugu Tomiyasu

Taisuke Matsumoto

Junji Tanaka

Shofiur Rahman

Paris E. Georghiou

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Professor Carl Redshaw C.Redshaw@hull.ac.uk
Professor of Inorganic Materials Chemistry and REF Lead for Chemistry

Takehiko Yamato



Abstract

Macrocyclic [1.1.1]metacyclophanes (MCPs) containing benzene and benzofuran rings linked by methylene bridges and which can be viewed as calixarene analogues, have been synthesized by demethylation of [3.3.1]MCP-diones with trimethylsilyl iodide (TMSI) in MeCN. The [3.3.1]MCP-diones are synthesized by using (p-tolylsulfonyl)methyl isocyanide (TosMIC) as the cyclization reagent in N,N-dimethylformamide (DMF) with an excess of sodium hydride. ¹H NMR spectroscopy revealed that the remaining hydroxyl group on the phenyl ring is involved in intramolecular hydrogen bonding with the oxygen of one of the benzofuran rings. O-Methylation at the lower rim of monohydroxy[1.1.1]MCP in the presence of K₂CO₃ in acetone afforded a novel and inherently chiral calixarene analogue, namely the macrocyclic [1.1.1]MCP, 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, which caused a splitting of the corresponding methylene protons to AB patterns. Single crystal X-ray analysis revealed the adoptation of a hemisphere-shaped cone isomer. DFT calculations were carried out to investigate the energy-minimized structures and the hydrogen bonds of the synthesized MCPs.

Citation

Islam, M. M., Tomiyasu, H., Matsumoto, T., Tanaka, J., Rahman, S., Georghiou, P. E., …Yamato, T. (2015). Synthesis and conformational studies of chiral macrocyclic [1.1.1]metacyclophanes containing benzofuran rings. Organic & biomolecular chemistry, 13(34), 9055-9064. doi:10.1039/c5ob01002k

Journal Article Type Article
Acceptance Date Jul 17, 2015
Online Publication Date Jul 20, 2015
Publication Date Jul 20, 2015
Deposit Date Jul 22, 2015
Publicly Available Date Nov 23, 2017
Journal Organic and biomolecular chemistry
Print ISSN 1477-0520
Electronic ISSN 1477-0539
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 13
Issue 34
Pages 9055-9064
DOI https://doi.org/10.1039/c5ob01002k
Keywords Benzofuran rings , Macrocyclic [1.1.1]metacyclophanes , MCPs
Public URL https://hull-repository.worktribe.com/output/376712
Publisher URL http://pubs.rsc.org/en/Content/ArticleLanding/2015/OB/C5OB01002K#!divAbstract
Copyright Statement ©2016 University of Hull
Additional Information Authors' accepted manuscript of article published in: Organic and biomolecular chemistry, 2015 at http://pubs.rsc.org/en/...C5OB01002K#!divAbstract

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