Convenient regioselective functionalization at the upper-rim of p-tert-butylcalix[8]arene through a protection–deprotection procedure

Gaeta, Carmine; Gregoli, Luisa; Martino, Marco; Neri, Placido

doi:10.1016/s0040-4039(02)02204-9

Cited by 29 publications

(15 citation statements)

References 17 publications

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“…To overcome this kind of problem, we decided to resort to intramolecular bridging as a very convenient method to shape and preorganize larger calixarene macrocycles. [17,18] Thus, we focused our attention on doubly bridged calix [7]arene derivatives, [10] such as 2 (Scheme 1), in which the presence of two short bridges at the 1,4-and 2,3-positions led to a high level of preorganization and suggested potential applications as molecular hosts in supramolecular chemistry. The 1,4-bridging gives rise to two different tetra-and trimeric subunits in 2 defined by the four alkylated and the three unalkylated phenol rings, respectively.…”

Section: Introductionmentioning

confidence: 99%

Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative

Gaeta

Talotta

Farina

et al. 2011

Chemistry A European J

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The shaping of a calix[7]arene macrocycle into cone-like structure 3, through exhaustive alkylation of doubly bridged calix[7]arene derivative 2 with bulky groups, has been investigated. Conformational details about the structure adopted by calix[7]arene derivative 3 in solution have been obtained by using chemical shift surface maps, as previously reported by our group. Thus, chemical shift contour plots indicated that 3 adopted a cone-shaped structure in solution analogous to that adopted by the known p-tert-butylcalix[7]arene heptacarboxylic acid derivative 4. Interestingly, the X-ray structure of derivative 3 showed a high degree of similarity to the theoretical structure, which confirmed the validity of the contour plots method. The preorganized calix[7]arene host 3 showed interesting recognition abilities toward both organic and alkali cations. In fact, an unprecedented endo-cavity complexation of linear and branched alkyl ammonium cations with a larger calix[7]arene host was evidenced. A comparable affinity for branched tBuNH(3)(+) and linear nBuNH(3)(+) guests was observed.

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Section: Introductionmentioning

confidence: 99%

Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative

Gaeta

Talotta

Farina

et al. 2011

Chemistry A European J

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“…Two regioisomeric [1+1] products 17 and 18 were isolated from the reaction mixture by a tedious chromatographic procedure and characterized: an A,D-bridged macrocycle 17 and an A,E-bridged compound 18 were formed in 12 and 10 % yields, respectively. Remarkably, experiments involving the related 1,3-xylylene bridge have been described in which either A,E (Neri and co-workers, [25] 80 %) or A,D (Shinkai and co-workers, [26] 20 %)-bridged compounds were found. The main difference between these bridging experiments seems to be in the metal ion (Na + [26] and Cs + [25] ) of the base employed.…”

Section: Resultsmentioning

confidence: 99%

Calix[5]‐ and Calix[8]arenes Bridged with Heterocycles

2005

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Calix[5]arene (2) and calix[8]arene (4) reacted with bis(bromomethyl)‐substituted heterocycles such as pyridine and 1,10‐phenanthroline to give [1+1] condensation products 10 and 16–18 (bridged bimacrocycles) and [2+1] dicalixarenes 11, 13 and 14, all of which were fully characterized. Although the bridging capability of both bridging units 5 and 6 is surprisingly similar, calix[5]arene (2) could only be bridged with the pyridine derivatives 5. With calix[8]arene (4), the 1,10‐phenanthroline bridging reagent 6 gave a cleaner product spectrum than the pyridine reagent 5. The 1,10‐phenanthroline‐bridged calix[8]arene 16 was characterized by X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…[18] Further per-O-alkylation of the remaining phenolic moieties and removal of the bridge by hydrogenolysis afforded the 1,2,3,5,6,7-hexa-O-alkylated compounds 3.19 and 3.20 in good overall yields. The two residual 1,5-phenolic moieties were notably used for the selectivemodification of the large rim (see section 4b elow) or the introductionofq uinone moieties.…”

Section: Covalent Strategymentioning

confidence: 99%

“…Typical functional groups that wereu sed in this contexta re detailed in Scheme 11. [18,26] One limit to this strategy is that ap oor discrimination between the various aromatic moieties is generally observedi nt he case of strong reactants such as SO 3 .W ith the milderH SO 3 Cl reactant however, excellent selectivity was obtained, even for the ipso reaction.…”

Section: Remote Control Of Large Rim Functionalization By the Small Rmentioning

confidence: 99%

Rational Strategies for the Selective Functionalization of Calixarenes

et al. 2015

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Calixarenes are widely used as molecular platforms in supramolecular chemistry.T heir efficient modification is key for appendingf unctional moieties such as binding, sensing, chiral, or hydrophilic subunits. Due to the presence of multiple identicalf unctional groups, selectivef unctionalization of such macrocyclic compounds is highly challenging. Indeed, the control of the chemo-, regio-, stereo-as wella s iteroselectivity is required. Thisr eview describes rational methods leadingt oahigh degree of regio-and/or iteroselectivitya nd classifies them into specific strategies. Many of these strategies are conceptually very general and hopefully will be as ource of inspiration for developing selectivem ethods for other macrocyclic platforms.

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Convenient regioselective functionalization at the upper-rim of p-tert-butylcalix[8]arene through a protection–deprotection procedure

Cited by 29 publications

References 17 publications

Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative

Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative

Calix[5]‐ and Calix[8]arenes Bridged with Heterocycles

Rational Strategies for the Selective Functionalization of Calixarenes

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