A New Method to prepare an e,e,e Trisadduct of C60 Using a ProtectionDeprotection Sequence

Abstract

A racemic mixture of the e,e,e Bingel-trisadduct, tris[di(ethoxycarbonyl)methano][60]fullerene 3 was synthesized by malonate additions (Bingel reaction) following by retro Diels-Alder reactions using a C60 tris-e,e,e adduct of anthracene 1 as precursor. Using this approach, the anthracenes act as protective groups and help orient the new additions so that poly-adducts with particular geometries are obtained. From the e,e,e anthracene-trisadduct 1 we also obtained the mono[di(ethoxycarbonyl)methano][60]fullerene 6 and bis [di(ethoxycarbonyl)methano][60]fullerene 7. This approach exhibits a total yield of 4,2 % for the e,e,e tris malonate adduct, gives rise to less complex reaction mixtures and makes it easier to separate and characterize the compounds than other methods. The compounds obtained where characterized by UV/VIS, FT-IR, 1H NMR, and MALDI-TOF.

The intermolecular anthracene-transfer in a regiospecific antipodal C60difunctionalization

“…8,[51][52][53][54][55][56][57] Sequential addition reactions to create multi-adducts with exceptional architectures were presented, [57][58][59][60][61][62][63] including reactions between C 60 and anthracenes, where mono-, [16][17][18]21,26,64 bis-, 19,[64][65][66][67][68] and specific tris-adducts were reported. 63,69 The kinetic and thermodynamic driving forces for the formation of specific bis-and tris-adducts has become a much discussed issue. 8 Thermolysis of the crystalline mono-adduct of C 60 and anthracene has provided a strikingly efficient means for achieving regiospecific antipodal bis-addition.…”

The intermolecular anthracene-transfer in a regiospecific antipodal C60 difunctionalization

“…8,[51][52][53][54][55][56][57] Sequential addition reactions to create multi-adducts with exceptional architectures were presented, [57][58][59][60][61][62][63] including reactions between C 60 and anthracenes, where mono-, 16-18, 21, 26, 64 bis-, 19,[64][65][66][67][68] and specific tris-adducts were reported. 63,69 The kinetic and thermodynamic driving forces for the formation of specific bis-and tris-adducts has become a much discussed issue. 8 Thermolysis of the crystalline mono-adduct of C 60 and anthracene has provided a strikingly efficient means for achieving regiospecific antipodal bis-addition.…”

Sequential Tether‐Directed Synthesis of Pentakis‐Adducts of C60 with a Mixed [3:2] Octahedral Addition Pattern

“…So far, five general approaches to the synthesis of pentakis‐adducts of C 60 with a local C 2 v ‐symmetric addition pattern have been reported (Figure ) ,. [8a], Our group published the first access to pentakis(diethyl malonates) of C 60 in 1994 by stepwise nucleophilic cyclopropanation and subsequent chromatographic separation of the correct regioisomer (Figure , 1 ). The second approach involves a protection/deprotection sequence through thermal or photochemical cleavage reactions .…”

“…Subsequent cyclopropanations of the three freely accessible e double bonds gave rise to the formation of [3:2] pentakis‐adducts 5 bearing fully addressable octahedral addition sites. In the next approach, a [3:2] pentakis‐adduct with three anthracenes and two malonate addends was generated (Figure , 6 ). As a precursor, an e , e , e tris‐adduct obtained by a Diels–Alder cycloaddition between C 60 and anthracene was used.…”

“…Characteristic examples of pentakis‐adducts of C 60 with an incomplete octahedral addition pattern synthesized by five different reported approaches ,. [8a], …”