Pyrimidine ortho-quinodimethanes. Part 2: Synthesis of new [60]fullerene adducts based on substituted pyrimidine derivatives and their 1H NMR dynamic study

Herrera, Antonio; Martínez‐Álvarez, Roberto; Martı́n, Nazario; Chioua, Mourad; Chioua, Rachid; Molero, Dolores; Sánchez-Vázquez, Ángel; Almy, John

doi:10.1016/j.tet.2009.05.026

Cited by 9 publications

(10 citation statements)

References 47 publications

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“…The Diels–Alder reaction of a variety of dienes with C 60 , acting as dienophile, affords the preparation of fullerene cycloadducts . The odd‐electron ions M ●− generated under negative ESI conditions from these cycloadducts undergo under CID conditions a retro‐cycloaddition reaction forming the corresponding [60]fullerene odd‐electron ion at m/z 720 as the base peak . On the other hand, the 1,3‐dipolar cycloaddition of appropriate azomethine ylides to C 60 and C 70 permits the preparation of pyrrolidine fused fullerenes .…”

Section: Resultsmentioning

confidence: 99%

Effect of substituents and protonation on the mechanism of 1,3‐dipolar retro‐cycloaddition reaction of pyrrolidino[60]‐ and [70]fullerenes

et al. 2011

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The mass spectra of new substituted pyrrolidino[60]- and [70]fullerenes have been obtained using electrospray ionization conditions in the positive and negative mode of detection with two different mass spectrometers, a quadrupole ion trap and a Fourier transform ion cyclotron resonance. Radical anions M(●-) and deprotonated molecules [M-H](-) are formed under negative electrospray ionization mass spectrometry conditions, and the collision-induced dissociations of both ionic species have been studied. Either negative odd-electron ions or negative even-electron ions undergo a retro-cycloaddition process forming the corresponding fullerene product ions C(60)(●-) and C(70)(●-). The generation of fullerene radical anions from deprotonated molecules is a new exception of the "even-electron rule." In contrast, the protonated molecules [M + H](+) obtained from the positive mode of detection do not undergo this cycloreversion reaction, and the MS(n) experiment reveals a variety of eliminations of neutral molecules involving different hydrogen shifts and multiple bond cleavages that lead eventually to substituted methanofullerene fragment ions. The observed fragmentations can be correlated with the electronic character of the substituents attached to the heterocyclic moiety. The results obtained from the thermal reactions of these compounds, carried out under different pH conditions, correlate well with those obtained in gas phase. The different behaviors between protonated and unprotonated molecules and ions can be explained assuming that the retro-cycloaddition reaction takes place only when the nitrogen atom of the pyrrolidine ring (the basic center of the molecule) is unprotonated both in gas and condensed phase. The protonation of the NH group inhibits the cycloreversion process, and therefore different fragmentations take place. The detailed mechanisms of the formation and evolution of the intermediate fragments are described.

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Section: Resultsmentioning

confidence: 99%

Effect of substituents and protonation on the mechanism of 1,3‐dipolar retro‐cycloaddition reaction of pyrrolidino[60]‐ and [70]fullerenes

et al. 2011

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“…38 A variety of new fullerodihydroquinazoline derivatives have been obtained from Diels-Alder reaction of various pyrimidine ortho-quinodimethanes generated in situ with C 60 fullerene. 39 The hetero-Diels-Alder reaction of C 60 with nitrosoalkene generated in situ from the corresponding a-bromooximes by treatment with Na 2 CO 3 was explored, and led to the formation of a new type of stable C 60 -fused dihydrooxazine derivatives. 40 The Mitsunobu condensation between alcohols and acids has been successfully applied to the derivatisation of methano-C 60 -fullerene mono-adduct bearing 2 hydroxyl groups and a hexakis-adduct with 12 hydroxyl functions.…”

Section: Production Separation and Properties Of Fullerenesmentioning

confidence: 99%

Fullerenes

Darwish¹

2010

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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“…A RDA process is observed when substituted tetrahydroquinazolinofullerenes undergo a fragmentation forming as the only product ion the [60]fullerene [32]. It is interesting to note that in the case of the bis(methylsulfonyl)tetrahydroquinazolinofullerenes, these compounds extrude consecutively two sulfur dioxide molecules before undergoing the usual RDA process leading to the C 60 ion [33].…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometry Studies of the Retro-Cycloaddition Reaction of Pyrrolidino and 2-Pyrazolinofullerene Derivatives Under Negative ESI Conditions

Delgado

Filippone

Martín‐Domenech

et al. 2011

J. Am. Soc. Mass Spectrom.

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Substituted pyrrolidino-and 3-alkyl-2-pyrazolinofullerenes ionize under ESI and MALDI mass spectrometry conditions and negative mode of detection undergoing mass spectral fragmentations, which can be easily correlated with the reported results for the thermal and electrochemical retro-cycloaddition reactions of these compounds. 2-Pyrazolinofullerenes lead directly to a [60] fullerene product ion formed through a retro-cycloaddition process regardless of the substituents attached at the carbon and nitrogen atoms of the heterocyclic ring. These results are different from whose reported for the thermal and electrochemical processes. In contrast, pyrrolidinofullerenes undergo different fragmentative reactions depending upon the substituents (hydrogen, alkyl, or acyl) attached at the nitrogen atom of the heterocyclic ring leading eventually to the pristine C 60 in the last step of the fragmentation pathway.

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Pyrimidine ortho-quinodimethanes. Part 2: Synthesis of new [60]fullerene adducts based on substituted pyrimidine derivatives and their 1H NMR dynamic study

Cited by 9 publications

References 47 publications

Effect of substituents and protonation on the mechanism of 1,3‐dipolar retro‐cycloaddition reaction of pyrrolidino[60]‐ and [70]fullerenes

Effect of substituents and protonation on the mechanism of 1,3‐dipolar retro‐cycloaddition reaction of pyrrolidino[60]‐ and [70]fullerenes

Fullerenes

Mass Spectrometry Studies of the Retro-Cycloaddition Reaction of Pyrrolidino and 2-Pyrazolinofullerene Derivatives Under Negative ESI Conditions

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