Regio‐ and Diastereoselective Bisfunctionalization of C₆₀ and Enantioselective Synthesis of a C₆₀ Derivative with a Chiral Addition Pattern

Abstract

A versatile and simple method provides access to covalent bisadducts of C60 with high regio‐ and diastereo‐selectivity. Starting from optically pure bis(malonate) derivatives and C60, a double Bingel reaction afforded optically active cis‐3 bisadducts (ee > 97%), whose chirality results exclusively from the addition pattern.

Bucky Ligands: Synthesis, Ruthenium(II) Complexes, and Electrochemical Properties

“…C 60 was isolated from the commercially available C 60 /C 70 mixture according to a previously reported method. [25] ( AE )-2-[2-(3,4,5,6-Tetrahydro-2H-pyran-2-yloxy)ethoxy]ethanol ( AE )- (7), [11] 4'-hydroxy-2,2':6',2''-terpyridine (15), [18] 4'-methylsulfonyl-2,2':6',2''-terpyridine (16), [19] 2,2'-bipyridine-4,4'-dicarbonyl chloride (5), [17] [Ru(tpy)Cl 3 ] [26] and [Ru(4'-Me 2 Ntpy)Cl 3 ] [26] were prepared as previously reported. Evaporation and concentration in vacuo were done at water aspirator pressure; products were dried in vacuo at 10 À2 Torr.…”

Synthesis and Chiroptical Properties of Enantiomerically Pure Bis- and Trisadducts of C60 with an Inherent Chiral Addition Pattern

“…It is interesting to note that the Cotton effects of the C 2 -symmetrical bisadducts 10 and 11 are significantly larger than those of the C 3 -symmetrical trisadducts 15 and the D 3 -symmetrical trisadducts 14 (Figure 7, p. 352) but are comparable to those of the C 2 -symmetrical bisadduct 3 measured by Diederich and coworkers. [10] We explain this behavior with the higher symmetry of the trisadducts, which cause a less pronounced distortion of the conjugated p system within the C 60 chromophore. This explanation is also corroborated by the fact that the maximum De values for enantiomerically pure C 76 derivatives are up to twice as large as those for 10 and 11.…”

“…First efforts in this direction by the groups of Diederich [10] and Nakamura [11] provided access to enantiomerically pure adducts with the C 2 symmetrical addition pattern C ( Figure 1) by diastereoselective tether-controlled bisadditions. Enantiomerically pure adducts of C 70 with inherent chiral addition patterns were isolated by Diederich and coworkers [12] by the addition of chiral addends and the subsequent separation of the diastereomeric adducts.…”

Synthetic Strategies towards Fullerene-Rich Dendrimer Assemblies

“…Fusion of the two precursors gave a bismalonate which was reacted under classical Bingel conditions with C 60 , I 2 and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) to afford carboxylic acid 1 after treatment with TFA. Importantly, the well-established strategy via 1,3-phenylenebis(methylene)-tethered bis-malonates produced regioselectively the cis-2 addition pattern at C 60 [14]. Acid 1 has then been engaged in the preparation of well-defined fullerene-rich nanostructures as obtained by the divergent approach.…”

“…The required bismalonate precursor equipped with a phenolic OH group and two long alkyl chains was obtained after four steps from the commercially available 5-hydroxyisophthalic acid. The macrocyclic bis-adduct was thus produced in 34% yield using the highly regioselective reaction developed by Diederich [37]. Reaction of two equivalents of the first generation precursors bearing a phenol moiety with silicon(IV) phthalocyanine (SiPc) dichloride proceeded smoothly in the presence of K 2 CO 3 to produce the first generation triad 52 in 27% yield under formation of silicon-oxygen bonds (Figure 7).…”