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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.

Journal Article Type Article
Publication Date Jul 20, 2015
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
APA6 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
DOI https://doi.org/10.1039/c5ob01002k
Keywords Benzofuran rings , Macrocyclic [1.1.1]metacyclophanes , MCPs
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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