Diels-Alder reactions of fullerenes

Diels-Alder reaction of fullerenes with complex dienes type 52 (Figure 2.6) which have a 2,3-bis-(methylene) bicyclo[2.2.2]octane unit [49]. 

Cheng and coworkers142 reported the first Diels-Alder reactions of fullerenes with dienes having an electron-withdrawing group at C(l). The reactions with [60]fullerene proceeded at elevated temperatures to afford the corresponding adducts with moderate yields. The adducts appeared to be more stable than the adducts of electron-rich dienes. 

A review of Diels-Alder reactions of fullerenes with acyclic and cyclic dienes has been presented. The addition of substituted pyrimidine o-quinodimethanes (75) to [60]fullerenes yields novel organofullerenes (76) bearing a pyrimidine nucleus covalently attached to the Ceo cage (Scheme 26). The Diels-Alder dimerization of cyclopenta[/]phenanthrene (77) with isobenzindene (78) yields the dimer (79) in 85% yield (Scheme 27). Further evidence has been supplied to support an early reorganization of the r-network in the dimerization of 2-methoxycarbonylbuta-1,3-diene. The Lewis acid-catalysed Diels-Alder reactions of acrylate derivatives of new carbohydrate-based chiral auxiliaries with cyclohexadiene show excellent endo. exo... 

Scheme 8.14 Diels-Alder reactions of fullerene with a 9-substituted anthracene.

Diels-Alder reactions of butadienes 13 and 2,3-di-w-propylbutadiene 14 with [60]-fullerene 15 led to several fullerene derivatives [15-17] (Scheme 2.10). Dienes 13 and 14 bore electron-donating groups, but the reactions also occurred with electron-withdrawing substituents due to the sufficiently low-energy LUMO of Ceo-... 

Exohedral functionalization of [60]-fullerene by [4 -i- 2] cycloadditions. Diels-Alder reactions of [60]-fullerene with electron-rich 2,3-dioxysubstituted-1,3-butadienes [146]... 

Almena I., Carrillo J. R., De la Cruz P., Diaz-Ortiz A., Gomez-Escalonilla M. J., De la Hoz A., Langa F., Prieto P., Sanchez-Migallon A. Application of Microwave Irradiation to Heterocyclic Chemistry Targets Heterocyclic Systems-Chemistry and Properties 1998 2 281-308, Eds. Attanasi O. A. and Spinelli D., Pb. Soc. Chim. Ital. Keywords Diels-Alder reactions, [60]-fullerene... 

Sliwa W. Diels-Alder Reactions of EuUerenes Fullerene Sci. Technol. 1997 5 1133-1175... 

Keywords Diels-Alder reaction of polymer supported cyclopentadiene with fullerene... 

Keywords Diels-Alder reaction of exohedral functionalization of fullerenes and preparation of heterocyclic fullerenes... 

The scope of the microwave technique in the preparation of fullerene derivatives was determined in the well known Diels-Alder reaction of C6o with anthracene (1) [71], which has been reported to occur under thermal conditions (13% [71a], reflux, toluene, three days 25% [71b], reflux, benzene, 12 h) (Scheme 9.22). In addition to 76, multiply-substituted adducts that undergo cycloreversion to the starting materials were formed. 

Novel pyrazine-containing cydoadducts 80a-c were synthesized by Diels-Alder reaction of [60]fullerene with the corresponding 2,3-bis(bromomethyl)pyrazine derivatives 79a-c (Scheme 9.23) [73] the 2,3-pyrazinoquinodimethanes were trapped as the Diels-Alder adducts by reaction with [60]fullerene under reflux in o-dichloroben-zene (ODCB) as solvent with classical heating and under the action of microwave ir-... 

Recently, the reaction of masked ortho-benzoquinone [92] with C60 was tested [93]. The [4+2] cycloaddition reaction of such electron-deficient dienes with fullerenes resulted in the formation of highly functionalized bicyclo [2.2.2] octenone-fused fullerenes. The reactants were generated in situ by the oxidation of the readily available 2-methoxy phenols with hypervalent iodine agents. For the several different masked ortho-benzoquinones that were tested, it was found that the yield of the cycloadducts depends on the nature of the starting materials and the reaction conditions. Other Diels-Alder reactions of such electron-deficient dienes with electron-poor fullerenes involved tropones [94], 1,3-butadienes substituted with electron-withdrawing groups [95], and 2-pyrone [96]. 

Further C6o derivatives of menthol include a menthyl malonate adduct119 and a carbamate derived from l,2-epimino[60]fullerene.429 Resin acid derivatives have been prepared by Diels-Alder reaction of C6o with methyl levopi-marate, whose parent acid can be isolated from rosin.430 Finally, a derivative of a-pinene was synthesized in the context of a study on the photochemically induced addition of allyl stannanes to Cr,o, a reaction presumably proceeding via SET from the stannane to the triplet excited fullerene.431... 

Wang and co-workers also evaluated the reactivity of 9-substituted anthracene in Diels-Alder reactions with fullerene. Corresponding adducts were prepared in high yields under solvent-free conditions using the high-speed vibration milling technique (Scheme 8.14). ... 

The Diels-Alder reactions of masked o-benzoquinones (MOBs) with [60] fullerene afforded novel and highly functionalized bicyclo-[2.2.2]-octenone-fused [60]fullerene derivatives... 

Nitropyridine and 4-nitropyridine A-oxide have been shown to react with iso-prene, 1-methoxy-l,3-butadiene, and Danishefsky s diene to produce isoquinoline cycloadducts. One asymmetric and asynchronous transition state (TS) was detected between the reactants and the cycloadduct with isoprene and two TS were observed when 1-methoxy-l,3-butadiene and Danishefsky s diene were used. The Diels-Alder reaction of highly substituted dihydropyridines with e-deficient alkenes produced highly substituted isoquinuclidines with high stereo- and regio-selectivity. The Diels-Alder cycloaddition of cyclopentadiene to lithium ion encapsulated [60]fullerene proceeds at a higher rate than with that of empty [60]fullerene. ... 

AMI calculations of the addition of o-quinodimethanes with Ceo show that the mechanism is concerted. The Diels-Alder reaction between fullerene (Ceo) and Danishefsky s diene proceeds via a stepwise mechanism involving a single-electron transfer from the diene to the fullerene. ... 

Methano-indene-fullerene, C6o(CH2)(Ind) (26), was synthesized in 47% yield by the Diels-Alder reaction of indene with 24. The product 26 is a mixture of regioisomers two isomers were successfully isolated by high-performance liquid chromatography (HPLC) separation and one (Cg-isomer) of two was crystallographically characterized (Figure 3.4). 

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