Higher Adducts of C60 by Tether-Directed Remote Functionalization: X-Ray Crystal Structure and Reactivity of a Chiral Hexakis-Cyclopropanated Fullerene with all Addends Located along an Equatorial Belt

Woods, Craig R.; Bourgeois, Jean‐Pascal; Seiler, Paul; Diederich, François

doi:10.1002/1521-3773(20001103)39:21<3813::aid-anie3813>3.0.co;2-5

Cited by 25 publications

(29 citation statements)

References 30 publications

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“…The molecular structure revealed the distinct helical nature of addition pattern A and allowed an unambiguous assignment of structure (AE)-1 to this compound (for details on the X-ray crystal structure, see the preliminary communication [11]). Distortion of the C 60 sphere in (AE)-1 due to the belt of six fused cyclopropane rings was found to be small, and its overall shape closely resembles that determined previously for bis-adduct (AE)-13 [25b].…”

mentioning

confidence: 72%

“…The optical endabsorption of these bright-yellow compounds appears around 450 nm, in agreement with the limited p-electron delocalization in the residual fullerene chromophore. They represent interesting building blocks for supramolecular (8) and covalent (11) fullerene-based nanoscaffolding. With the construction of molecular square 2 from 8, the first example of a supramolecular fullerene dimer was obtained.…”

Section: Physical Properties and Chemical Reactivity Of (Ae)-1: Prepamentioning

confidence: 99%

“…Here, we describe the application of this methodology to the preparation of hexakis-adducts of C 60 that are not available in stepwise-addition sequences in the absence of a template. In particular, we report the synthesis of the chiral derivative (AE)-1 by a short route that involves two sequential tether-directed remote functionalization steps (for a preliminary communication of parts of this work, see [11]). Compound (AE)-1 features a novel chiral, D 2 -symmetrical addition pattern, with all addition sites aligned in a distinct helical array along an equatorial belt.…”

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confidence: 99%

“…'''''-octacarboxylate(11). To 9 (12.0 mg, 8.87 mmol) and 10 (45.8 mg, 0.160 mmol) in deoxygenated CH 2 Cl 2 (1 ml), deoxygenated Me 2 SO (1 ml) was added to give a cloudy mixture.…”

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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

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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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confidence: 72%

Section: Physical Properties and Chemical Reactivity Of (Ae)-1: Prepamentioning

confidence: 99%

mentioning

confidence: 99%

“…'''''-octacarboxylate(11). To 9 (12.0 mg, 8.87 mmol) and 10 (45.8 mg, 0.160 mmol) in deoxygenated CH 2 Cl 2 (1 ml), deoxygenated Me 2 SO (1 ml) was added to give a cloudy mixture.…”

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confidence: 99%

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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

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“…Acid-catalyzed cleavage of the tertbutyl ester groups and the crown ether template afforded the corresponding tetracarboxylic acid 19 which was transformed over several steps into tetrol 20 and further into tetrakismalonate 21. The final step of the sequence, affording D 2 -symmetric hexakisadduct (±)-22 as sole product [29,40], consisted of two double tether-directed remote Bingel additions, multiple macrocyclizations which had previously been described as 'clipping reactions' and given access to tris-and tetrakisadducts of C 60 [41]. X-ray crystallography of (±)-22 confirmed all six cyclopropane rings to be arranged in a double-helical fashion with the corresponding axis passing through the unfunctionalized poles of the carbon sphere.…”

Section: Crown Ether Tethersmentioning

confidence: 99%