Regioselektive, durch einen Kronenether- Spacer kontrollierte Synthese vontrans-1- Fulleren-Bisaddukten: Alkalimetallionen- abhängige Redoxeigenschaften von Fulleren-Kronenether-Konjugaten

Bourgeois, Jean‐Pascal; Echegoyen, Luís; Fibbioli, Monia; Pretsch, Ernö; Diederich, François

doi:10.1002/(sici)1521-3757(19980803)110:15<2203::aid-ange2203>3.0.co;2-m

Cited by 29 publications

(21 citation statements)

References 43 publications

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“…CH 2 Cl 2 was dried over CaH 2 . Compounds 5 [15], 9 [19a], and (AE)-13 and 19 [25] were prepared according to literature procedures. All reactions were performed in standard glassware under an inert atmosphere of Ar.…”

Section: Experimental Partmentioning

confidence: 99%

“…We have recently showed that the Bingel macrocyclization of bis-malonates 14 or 15, bridged by an antibisfunctionalized dibenzo [18]crown-6 (DB18C6) tether, which is further rigidified by K ion complexation, afforded exclusively the trans-1 derivatives (AE)-13 or (AE)-16 in ! 50% yield (Scheme 3) [25] (for other regioselective trans-1 bisfunctionalizations, see [8] [26] [27]). We also demonstrated that the DB18C6 moiety in this fullerene-crownether conjugate is a true covalent template, which is readily removed by hydrolysis or transesterification.…”

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“…Upon coordination of a Zn 2 , Pt 2 , or Ag ion to the four pyridine ligands of two molecules of (AE)-18, we hoped to form supramolecular Novel hexakis-addition patterns of C 60 with the addend sites located along an equatorial belt fullerene dimers with interesting photophysical and redox properties. The synthesis of these novel construction modules started with dicarbaldehyde 19 [25], which was reduced with NaBH 4 in MeOH to diol 20 (Scheme 4). Since the isolation and purification of this highly polar molecule, which is only poorly soluble in organic solvents, proved to be difficult and tedious, it was not isolated but directly esterified as the crude product.…”

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Hexakis-Adducts of [60]Fullerene with Different Addition Patterns: Templated Synthesis, Physical Properties, and Chemical Reactivity

Bourgeois

Woods

Cardullo

et al. 2001

HCA

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Representatives of two classes of hexakis-adducts of C 60 were prepared by templated synthesis strategies. Compound 8 with a dipyridylmethano addend in a pseudo-octahedral addition pattern was obtained by DMAtemplated addition (DMA 9,10-dimethylanthracene; Scheme 1) and served as the starting material for the first supramolecular fullerene dimer 2. Hexakis-adduct 12 also possesses a pseudo-octahedral addition pattern and was obtained by a sequence of tether-directed remote functionalization, tether removal, and regioselective bis-functionalization (Scheme 2). With its two diethynylmethano addends in trans-1 position, it is a precursor for fascinating new oligomers and polymers that feature C 60 moieties as part of the polymeric backbone ( Fig. 1).With the residual fullerene p-electron chromophore reduced to a cubic cyclophane-type sub-structure (Fig. 4), and for steric reasons, 8 and 12 no longer display electrophilic reactivity. As a representative of the second class of hexakis-adducts, (AE)-1, which features six addends in a distinct helical array along an equatorial belt, was prepared by a route that involved two sequential tether-directed remote functionalization steps (Schemes 3 and 5). In compound (AE)-1, p-electron conjugation between the two unsubstituted poles of the carbon sphere is maintained via two (E)-stilbene-like bridges (Fig. 4). As a result, (AE)-1 features very different chemical reactivity and physical properties when compared to hexakis-adducts with a pseudo-octahedral addition pattern. Its reduction under cyclic voltammetric conditions is greatly facilitated (by 570 mV), and it readily undergoes additional, electronically favored Bingel additions at the two sterically well-accessible central polar 6-6 bonds under formation of heptakis-and octakis-adducts, (AE)-30 and (AE)-31, respectively (Scheme 6). The different extent of the residual p-electron delocalization in the fullerene sphere is also reflected in the optical properties of the two types of hexakis-adducts. Whereas 8 and 12 are bright-yellow (end-absorption around 450 nm), compound (AE)-1 is shiny-red, with an end-absorption around 600 nm. This study once more demonstrates the power of templated functionalization strategies in fullerene chemistry, providing addition patterns that are not accessible by stepwise synthetic approaches.1. Introduction. ± Among the higher adducts of buckminsterfullerene (C 60 ; for a recent example, see [1]), hexakis-adducts are increasingly attracting interest as threedimensional scaffolds for advanced materials applications [2] [3]. Among those, derivatives with a pseudo-octahedral (T h ) addition pattern have been the earliest and most widely investigated ones [4 ± 8]. Also known is a hexakis-adduct with a D 3 -symmetrical addition pattern [2]. Both types of hexakis-adducts are accessible by stepwise additions, and their addends are evenly distributed over the entire carbon sphere. In this paper, we describe the synthesis of new hexakis-adducts with the T hsymmetrical addition pattern, which are useful...

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Section: Experimental Partmentioning

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Hexakis-Adducts of [60]Fullerene with Different Addition Patterns: Templated Synthesis, Physical Properties, and Chemical Reactivity

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Woods

Cardullo

et al. 2001

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“…With the exception of cis-1, all possible bis-addition patterns (Scheme 7-1) have been obtained today and some interesting examples (42-54) [25,59,60,[64][65][66][67][68] for the various functionalization patterns are presented in Scheme 7-8.…”

Section: The Bingel Macrocyclizationmentioning

confidence: 99%

“…The formation of (+)-67. 4PF6 by self-assembly, following the elegant strategy developed by Stoddart and co-workers [80], is depicted in Substantial perturbations of the electronic structure of the fullerene were observed when an alkali metal cation was bound to the crown ether moieties in tt-trn.s-2 bij-adduct (+)-51 or trans-1 bis-adducts (-+)-53 [66]. In these compounds, the crown ether receptor site is positioned closely and tightly on the fullerene surface.…”

Section: Other Bis-functionalization Patternsmentioning

confidence: 99%

Regio‐ and Stereoselective Multiple Functionalization of Fullerenes

Diederich

Kessinger

1999

Templated Organic Synthesis

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The synthesis of multiple adducts of CW has attracted much attention in recent years [ 11.Investigations of covalent derivatives with varying degrees and patterns of addition make it possible to explore how characteristic fullerene properties are affected by functionalization-induced changes in the conjugated n-chromophore [2]. Furthermore, higher adducts of c 6 0 represent an unprecedented family of three-dimensional building blocks for molecular scaffolding targeting advanced fullerene materials and technologies [3]. The direct sequential multiple functionalization of the carbon sphere, however, is problematic in most cases, and isolation of a pure higher adduct usually requires tedious chromatographic isomer separation [4-61. Moreover, a great diversity of interesting addition patterns is not accessible by sequential derivatization. Therefore, we proposed in 1994 a more general approach to the regioselective formation of multiple adducts of c 6 0 by taking advantage of tether-directed remote functionalization techniques [7]. Such strategies had been initially developed by Breslow and co-workers for the selective functionalization of steroids and long-chain alkanes (see Chapter 6 ) [8]. Here, we illustrate how the application of non-covalent and covalent templates provides access to a great diversity of three-dimensionally functionalized fullerene building blocks. Templated synthesis now serves as a powerful tool for chemists interested in exploiting the outstanding technological potential of fullerenes and their covalent derivatives. Anthracenes as Reversible Covalent TemplatesAmong the most versatile reactions in fullerene chemistry is the Bingel cyclopropanation with 2-bromomalonate in the presence of base [9]. The problematics of regioisomeric product formation in nucleophilic additions to C,, is illustrated in the following, using this reaction as an example. By sequential double Bingel addition, Hirsch and co-workers obtained seven (1-7) out of eight possible bis-adducts named as cis-1-3, eface and edge (these two bis-adducts are identical if the two addends are identical), and truns-I -4 (Scheme 7-1) [lo, 111, which could be separated by high-performance liquid chromatography (HPLC). Only the cis-1 bis-adduct was not formed in detectable quantities due to steric interactions between the addends which are forced into close proximity. The e (3) and trans-3 (5) bis-adducts are the major products in the sequential double addition,

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Auf dem Weg zur vollständigen Kontrolle der sechsfachen Funktionalisierung von Buckminsterfulleren (C60) an oktaedrischen Positionen

Qian

Rubin

1999

Angewandte Chemie

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Regioselektive, durch einen Kronenether- Spacer kontrollierte Synthese vontrans-1- Fulleren-Bisaddukten: Alkalimetallionen- abhängige Redoxeigenschaften von Fulleren-Kronenether-Konjugaten

Cited by 29 publications

References 43 publications

Hexakis-Adducts of [60]Fullerene with Different Addition Patterns: Templated Synthesis, Physical Properties, and Chemical Reactivity

Hexakis-Adducts of [60]Fullerene with Different Addition Patterns: Templated Synthesis, Physical Properties, and Chemical Reactivity

Regio‐ and Stereoselective Multiple Functionalization of Fullerenes

Auf dem Weg zur vollständigen Kontrolle der sechsfachen Funktionalisierung von Buckminsterfulleren (C60) an oktaedrischen Positionen

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