Synthesis, structural properties, electrophilic substitution reactions and DFT computational studies of calix[3]benzofurans

Islam, Md. Monarul; Akther, Thamina; Ikejiri, Yusuke; Matsumoto, Taisuke; Tanaka, Junji; Rahman, Shofiur; Georghiou, Paris E.; Hughes, David L.; Redshaw, Carl; Yamato, Takehiko

doi:10.1039/c6ra06219a

Cited by 15 publications

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“…We previously reported the synthesis of calix[3]benzofurans which are unusual macrocycles bearing benzofuran units instead of only benzene rings. Recently, our group illustrated an efficient intramolecular cyclization synthetic route to produce macrocyclic [1.1.1]MCPs containing two and three benzofuran rings, using( p ‐tolylsulfonyl)methyl isocyanide (TosMIC) as the cross‐coupling cyclization reagent. In an analogous manner, the synthesis of 6,15,24‐tri‐ tert ‐butyl‐9,18,27‐trimethoxy[3.3.3]‐MCP‐2,11‐dione 5 was previously reported and is shown in Scheme .…”

Section: Resultsmentioning

confidence: 82%

Synthesis, Structures and DFT Computational Studies of [3.1.1]Metacyclophanes Containing Benzofuran Rings

et al. 2018

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[3.1.1]Metacyclophane ([3.1.1]MCP) 6 a containing two benzofuran rings was obtained by treatment of [3.3.3]MCP‐dione 5 with trimethylsilyl iodide. The precursor 5 was synthesized using (p‐tolylsulfonyl)methyl isocyanide (TosMIC) as the cyclization reagent. The 1H‐NMR spectrum of 6 a at room temperature reveals that it undergoes very fast conformational changes relative to the NMR time scale and that the phenolic hydrogen forms weak intramolecular hydrogen bonding with the oxygen of one of the benzofurans. O‐Methylation of 6 a afforded the calixarene analogue, macrocyclic [3.1.1]MCP 7 a whose 1H‐NMR spectrum reveals that it adopts a cone‐likeconformation in solution at room temperature and the alkoxy group is pointing above and away from the macrocyclic cavity.

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Section: Resultsmentioning

confidence: 82%

Synthesis, Structures and DFT Computational Studies of [3.1.1]Metacyclophanes Containing Benzofuran Rings

et al. 2018

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“…The demethylation of [3.3.1]MCP-dione 19 in acetonitrile with in-situ-generated TMSI produced a mixture of benzofuran ring-containing products, the symmetrical 22a and unsymmetrical 23a and a new spirobisdihydro-furan 24 in 24 , 45 and 5% yields, respectively ( Figure 6 ) [ 39 ]. It is presumed that the trihydroxy-diketo intermediate 21 is first formed, and then undergoes intramolecular TMSI-mediated cyclizations to form the observed products [ 39 , 40 , 41 ]. Sawada and co-workers had previously reported that the treatment of tetramethoxy [2.1.2.1]MCPs with TMSI formed hemisphere-shaped calixarene analogues containing a dihydrobenzofuran ring [ 42 , 43 ].…”

Section: Calixbenzofuran-analogous Mcps: Calix[3]benzofuran Analogmentioning

confidence: 99%

Section: Calixbenzofuran-analogous Mcps: Calix[3]benzofuran Analogmentioning

confidence: 99%

“…Solvent and gas-phase DFT determinations with calix[3]benzofuran MCPs 25a – e [ 40 ] reveal that both the saddle and corresponding cone conformers have lower ground-state energies in the solvent system than in the gas phase ( Figure 10 ).…”

Section: Calixbenzofuran-analogous Mcps: Calix[3]benzofuran Analogmentioning

confidence: 99%

“…The triformyl derivative 25c showed fast cone-saddle interconversion in solution, but, when the three formyl groups were reduced to form the corresponding trihydroxymethyl derivative 25d, the molecule adopted a fixed-cone conformation as with 25b. The acylation of 25a to form 25e once again led to the formation of a slowly-interconverting mixture of cone-saddle conformers (Table 1) [40]. A series of derivatives 25b-e of calix [3]benzofuran 25a were synthesized using typical electrophilic aromatic substitution reactions to investigate the influence of the substituents on the conformations of the calix [3]benzofurans.…”

Section: Calixbenzofuran-analogous Mcps: Calix[3]benzofuran Analoguesmentioning

confidence: 99%

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Calix[3]arene-Analogous Metacyclophanes: Synthesis, Structures and Properties with Infinite Potential

et al. 2020

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Calixarene-analogous metacyclophanes (CAMs) are a special class of cyclophanes that are cyclic polyaromatic hydrocarbons containing three or more aromatic rings linked by one or more methylene bridging groups. They can be considered to be analogues of calixarenes, since, in both types of molecules, the component aromatic rings are linked by methylene groups, which are meta to each other. Since the prototype or classical calix[4]arene consists of four benzene rings each linked by methylene bridges, which are also meta to each other, it can be considered to be an example of a functionalized [1.1.1.1]metacyclophane. A metacyclophane (MCP) that consists of three individual hydroxyl-group functionalized aromatic rings linked by methylene groups, e.g., a trihydroxy[1.1.1]MCP may therefore, by analogy, be termed in the broadest sense as a “calix[3]arene” or a “calix[3]arene-analogous metacyclophane”. Most of the CAMs reported have been synthesized by fragment coupling approaches. The design, synthesis and development of functionalized CAMs, MCPs, calixarenes and calixarene analogues has been an area of great activity in the past few decades, due their potential applications as molecular receptors, sensors and ligands for metal binding, and for theoretical studies, etc. In this review article, we focus mainly on the synthesis, structure and conformational properties of [1.1.1]CAMs, i.e., “calix[3]arenes” and their analogues, which contain three functionalized aromatic rings and which provide new scaffolds for further explorations in supramolecular and sensor chemistry.

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Synthesis and Structure of 1,2‐Dimethylene[2.10]metacyclophane and Its Conversion into Chiral [10]Benzenometacyclophanes

et al. 2017

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Bromination of 5,21‐di‐tert‐butyl‐8,24‐dimethoxy‐1,2‐dimethyl[2.10]metacyclophan‐1‐ene (MCP‐1‐ene; 1) with benzyltrimethylammonium tribromide exclusively afforded 1,2‐bis(bromomethyl)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐1‐ene (2). Debromination of 2 with Zn and AcOH in CH2Cl2 solution at room temperature for 24 h produced dimethylene[2.10]MCP 7 in 92 % yield, which is a stable solid compound. Compound 7 was treated with dimethyl acetylenedicarboxylate (DMAD) to provide 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate (8) in good yield. Diels–Alder adduct 8 was converted into a novel and inherently chiral areno‐bridged dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate 9, possessing C1 symmetry, by aromatization with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). A new type of N‐phenyl‐maleimide substituted 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐N‐phenylmaleimide 10 was also synthesized from 7 through treatment with N‐phenylmaleimide in toluene at 110 °C followed by aromatization with DDQ. Single‐crystal X‐ray analysis of 9 revealed the formation of a syn‐isomer.

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Synthesis, structural properties, electrophilic substitution reactions and DFT computational studies of calix[3]benzofurans

Abstract: Synthesis of highly flexible calix[3]benzofurans; effects of substituent groups on calix[3]benzofuran conformations were studied by DFT computational methods.

Cited by 15 publications

References 65 publications

Synthesis, Structures and DFT Computational Studies of [3.1.1]Metacyclophanes Containing Benzofuran Rings

Synthesis, Structures and DFT Computational Studies of [3.1.1]Metacyclophanes Containing Benzofuran Rings

Calix[3]arene-Analogous Metacyclophanes: Synthesis, Structures and Properties with Infinite Potential

Synthesis and Structure of 1,2‐Dimethylene[2.10]metacyclophane and Its Conversion into Chiral [10]Benzenometacyclophanes

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