ChemInform Abstract: Selective Functionalization on (60)Fullerene Governed by Tether Length.

Taki, Masumi; Sugita, Sachiko; Nakamura, Yosuke; Kasashima, Eiji; Yashima, Eiji; Nishimura, Jun

doi:10.1002/chin.199719119

Cited by 2 publications

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“…Nishimura and co-workers used bis(o-quinodimethanes) connected by a, mdioxamethylene tethers for the regioselective bis-functionalization by double Diets-Alder addition (Scheme 7-14) [93]. The tethered bis(o-quinodimethanes) were intermediately formed by heating the bis(bromomethy1) derivatives 72a-d together with C,,, in toluene in the presence of KI and [18]crown-6 [90].…”

Section: Formation Of Bis-adducts By Double Diels-alder Addition Of Tmentioning

confidence: 99%

“…After cleavage of the boronate esters, the resulting bis(boronic acid)-substituted fullerene should provide a specific recognition site for the sugar that served as the initial sugar template. Scheme 7-14 Regioselective bis-functionalizations by double Diels-Alder addition of tethered bis(o-quinodimethanes) to C60 [93,94]. Thus, compound 82 containing 3-O-methyl-~-glucofuranose as a template underwent a double Diels-Alder addition with C,, providing as the major product the trans4 bisadduct 83 [95].…”

Section: Formation Of Bis-adducts By Double Diels-alder Addition Of Tmentioning

confidence: 99%

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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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Section: Formation Of Bis-adducts By Double Diels-alder Addition Of Tmentioning

confidence: 99%

Section: Formation Of Bis-adducts By Double Diels-alder Addition Of Tmentioning

confidence: 99%