Revisit to the reaction of [60]fullerene with nitrile ylides generated from imidoyl chlorides and triethylamine

The reaction of [60]fullerene (C₆₀) with nitrile ylides generated from N-benzyl-4-nitrobenzimidoyl chloride/N-(4-chlorobenzyl)-4-nitrobenzimidoyl chloride and triethylamine gave only isomeric monoadducts of C₆₀ with [6,6]-closed structure. No [5,6]-open adduct of C₆₀ could be identified from these reactions. The previously reported [5,6]-open product of C₆₀ should be reassigned as a [6,6]-closed product.     

Subphthalocyanine fused dimers-C60 dyads: synthesis, characterization, and theoretical study

A donor-acceptor covalently linked dyad consisting of a subphthalocyanine fused dimer unit doubly-connected to a [60]fullerene has been prepared through double cycloaddition of the fused dimer, previously functionalized with aldehyde groups in the axial positions, to the fullerene (1,3-dipolar cycloaddition of azomethine ylides). The compound, isolated in several fractions, has been characterized and studied employing photophysical and electrochemical techniques. Molecular modeling of the distinct possible isomers was carried out using semiempirical methods.     

Expeditious synthesis of cis-1-methyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo-[3,2h]isoquinoline/[2,3-f]quinoline via azomethine ylide-alkene [3+2] cycloaddition

Expeditious syntheses of cis-1-methyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo-[3,2h]isoquinoline/[2,3-f]quinoline have been developed. The syntheses started with commercially available materials and afforded excellent overall yields in straightforward steps. Intramolecular azomethine ylide-alkene [3+2] cycloaddition is the key step in the construction of these pyrroloisoquinoline and pyrroloquinoline scaffolds. This route is much more atom-economic than those reported in the literature and is appropriate for scale-up synthesis.     

Synthesis of two pentaarylated [60]fullerene derivatives Ar_5C_(60)-H (Ar = p-MeC_6H_4, m-MeC_6H_4) and their novel electrochemical properties

Through one pot reaction of C60 with organocopper/magne-sium reagent ( p - MeQ H4 )2 CuMgBr or ( m - MeC6 H )2 -CuMgBr prepared from CuBr-Me2S and p-MeC6H4MgBr or m-MeC6H4MgBr and subsequent quenching with aqueous NH4Cl, two pentaarylated [60] fullerene derivatives (p-MeC6H4)5C60H (1) and (m-MeC6H4)5C60H (2) have been synthesized in 94% and 96% yields, respectively. While known compound 1 prepared via this improved method is unambiguously identified, new compound 2 is fully characterized by elemental analysis, IR, UV-vis, 1H NMR and 13C NMR spectroscopies. Additionally, electrochemical study shows that the two [60] fullerene derivatives 1 and 2 in dichloromethane solution display two sequential one-electron reductions which are shifted by about 0.4V towards more negative potential values with respect to free C60. Such remarkable cathodic shift is attributed to the multiple breakage of the double-bond conjugation within the fullerene core.     

Ruthenocene as a new donor fragment in [60]fullerene-donor dyads

Four novel fullerene derivatives containing ruthenocene as the donor fragment have been synthesized and their electrochemical and fluorescence properties have been studied. Steady state fluorescence studies suggest the existence of photoinduced electron transfer in these dyads.     

Supramolecular complexation studies of [60]fullerene with calix[4]naphthalenes—a reinvestigation

Estimations of equilibrium or association constant (K_ASSOC) values reported by many other groups for the supramolecular complexation between [60]fullerene (‘C₆₀’) with different macrocyclic hosts, in solvents such as toluene or carbon disulfide, for example, is often conducted by UV-vis absorption and/or ¹H NMR spectroscopy. In this paper, the complexation behaviour of two calix[4]naphthalene hosts with C₆₀ in toluene and carbon disulfide has been re-examined, using both of these methods. An analysis is presented of the data newly obtained, in light of recent advances and understanding published by others of the limitations of, in particular, the absorption spectroscopic methods. The discussion presented is also intended to aid those who may be unfamiliar with the nuances and limitations of the analytic models involving C₆₀ supramolecular complexation. Also presented is a general mechanism for C₆₀ supramolecular complexation studies, which lay the groundwork for further experiments.     

Study of the structural and electronic properties of 1-(4, 5 and 6-selenenyl derivatives-3-formyl-phenyl) pyrrolidinofullerenes

A series of 1-(4, 5 and 6-selenenyl derivatives-3-formyl-phenyl) pyrrolidinofullerenes molecules C₆₀-C₂H₄N-[3-(CHO)C₆H₃SeX] were investigated theoretically by performing Density Functional Theory calculations at the B3LYP/3-21G^∗ level of the theory. The substituents include: X = CN, CH₂CH(NH₂)CO₂H and CH₂CH₂CH(NH₂)CO₂H. We have selected these substituents to be in ortho, meta and para positions with relation to formyl group in order to show the effect of such structural change on the electronic properties of the molecules. The theoretical IR spectra, physical, chemical and thermodynamics properties of the molecules studied are obtained and discussed.     

The reactions of 3-ethoxycarbonylmethylene-3,4-dihydroquinoxalin-2(1H)-one and its derivatives in the synthesis of benzodiazepines and benzimidazoles: reinvestigation,structural reassignment,and new insight

The reaction of 3-ethoxycarbonylmethylene-3,4-dihydroquinoxalin-2(1H)-one with the Vilsmeier reagent, the treatment of 3-(3,4-dihydroquinoxalin-2(1H)-on-3-yl)-1,2-dihydro-1,5-benzodiazepin-2(1H)-one hydrochloride with 10% sodium hydroxide and 3-benzimidazoylquinoxalin-2(1H)-one with both 1,2-phenylenediamine dihydrochloride, and the reactions of 1,2-phenylenediamine have been reinvestigated and the structures of these reaction products have been revised. It has been shown that in all the three cases other regioisomers of products have been formed as distinct from the literature data. The mechanisms to explain the formation of the products are suggested.     

Synthesis and Characterization of a Squarylium Cyanine Dye with Two [60]Fullerene Units

Fullerene derivatives containing two or more [60]fullerene units may exhibit interesting properties1. There have been reported a limited number of organofullerenes with two or more cages, and the synthetic procedures are an oxidative coupling reaction of terminal alkynes2, bifunctional cycloaddition reactions such as diazo compounds3, dienes4 or (-amino acids and aldehydes 1, 3-dipolar cycloaddtion5, cyanogen di-N-oxide as a double 1, 3-dipole6. Oxo- and methylene-bridged [60]fullerene dimers …     

[60]Fullerene adducts with 9-substituted anthracenes: mechanochemical preparation and retro Diels-Alder reaction

Three 9-substituted anthracene derivatives, that is, 9-hydroxymethylanthracene (2), 9-methoxymethylanthracene (3) and bis(9-anthrylmethyl) adipate (6), were chosen as the model compounds to evaluate the reactivity in their Diels-Alder reactions with [60]fullerene and in retro Diels-Alder reactions of the formed cycloadducts. Corresponding adducts 4, 5 and 7 were prepared in high yields under solvent-free conditions using high-speed vibration milling technique. In order to determine thermal stabilities of adducts 4, 5 and 7, their dissociations in the temperature range of 40-65 °C were investigated. Fitting the dissociation rates and temperatures to the Arrhenius equation gives the activation energies of 25.8, 21.8 and 24.9 kcal/mol for compounds 4, 5 and 7, respectively.     

Thermal and catalytic reactions of ethyl diazopyruvate with [60]fullerene

New stable [6,6]-methano cycloadducts and fulleropyrazolines containing electron-withdrawing groups have been obtained by the reaction of ethyl diazopyruvate with [60]fullerene. The results obtained by a systematic study conducted both in thermal and catalytic conditions have provided crucial indications concerning the mechanism of this important cluster opening process in fullerene chemistry.     

A new reaction of [60]fullerene with nitriles and EtMgBr in the presence of Ti(Oi-Pr)4

The reaction of C₆₀ with EtMgBr and different nitriles in the presence of Ti(Oi-Pr)₄ as the catalyst was performed for the first time to give novel fullerotetrahydropyridines.     

A novel entry into 1-methyl- and 1-aryl-octahydropyrrolo[3,4-b]pyrroles and their N-1-C-2 fused derivatives: stereoselective synthesis via an intramolecular azomethine ylide cycloaddition reaction

Synthesis of some novel pyrrolo[3,4-b]pyrrole derivatives has been accomplished in good yields by the intramolecular azomethine ylide cycloaddition reaction of a strategically situated unactivated alkenyl aldehyde with various secondary amino acids. A cis fused cycloadduct was formed in all cases.     

Cycloaddition of trifluoromethyl azafulvenium methides: synthesis of new trifluoromethylpyrrole-annulated derivatives

The chemistry of trifluoromethyl azafulvenium methides was explored leading to a new route to trifluoromethylpyrrole-annulated systems. The first evidence of azafulvenium methides acting as 1,3-dipoles is reported. These azafulvenium methides showed site selectivity in the reaction with strong electron-deficient dipolarophiles leading exclusively to 1,3-cycloadducts. In the cycloaddition with less-activated dipolarophiles 1,7-cycloadducts resulting from [8π+2π] cycloaddition are also formed. FMO analysis of the cycloaddition reactions allowed the rationalization of the observed selectivity.     

Synthesis of [60]Fullerene Hybrids Endowed with Steroids and Monosaccharides: Theoretical Underpinning as Promising anti-SARS-CoV-2 Agents

Cyclopropanation reactions between C₆₀ and different malonates decorated with monosaccharides and steroids using the Bingel-Hirsch methodology have allowed the obtention of a new family of hybrid compounds in good yields. A complete set of instrumental techniques has allowed us to fully characterize the hybrid derivatives and to determine the chemical structure of monocycloadducts. Besides, the proposed structures were investigated by cyclic voltammetry, which evidenced the exclusive reductive pattern of fullerene Bingel-type monoadducts. Theoretical calculations at the DFT-D3(BJ)/PBE 6-311G(d,p) level of the synthesized conjugates predict the most stable conformation and determine the factors that control the hybrid molecules′ geometry. Some parameters such as polarity, lipophilicity, polar surface area, hydrophilicity index, and solvent-accessible surface area were also estimated, predicting its potential permeability and capability as cell membrane penetrators. Additionally, a molecular docking simulation has been carried out using the main protease of SARS-CoV-2 (Mpro) as the receptor, thus paving the way to study the potential application of these hybrids in biomedicine.     

Selective addition of H2O to fullerene C60 catalyzed by Ti, Zr, and Hf catalysts

Selective addition of H₂O to fullerene C₆₀ catalyzed by Cp₂MCl₂ (M = Ti, Zr, Hf) catalysts to yield 1-hydroxy-1,2-dihydrofullerene has been realized for the first time.     

Unexpected one-pot synthesis of new polycyclic coumarin[4,3-c]pyridine derivatives via a tandem hetero-Diels-Alder and 1,3-dipolar cycloaddition reaction

O-Methyl-4-coumarincarbaldehyde oxime reacted as an azadiene with electron-deficient and electron-rich dienophiles to give, via one-step hetero-Diels-Alder cycloaddition reactions, the corresponding 5H-coumarin[4,3-c]pyridin-5-ones. When excess of the dienophile was used, fused azatetracyclo derivatives were also formed via a tandem Diels-Alder and 1,3-dipolar cycloaddition reaction of the dienophile to an azomethine ylide formed by the intermediate 2,3-dihydro-5H-coumarin[4,3-c]pyridine-5-one. The regio- and stereoselectivities of the new compounds correspond well with spectroscopic (2D NMR) and theoretical data. A possible mechanistic scheme is provided.     

Studies on 5-aminoisoxazole derivatives: Synthesis of some new fused isoxazoles

Several new fused isoxazole derivatives could be obtained utilising 5-amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl and 5-amino-4-cyano-3-trichloromethyl-isoxazoles as starting components.

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Untersuchungen an 5-Aminoisoxazol-Derivaten: Synthese einiger neuer kondensierter Isoxazole

Zusammenfassung Es konnten einigen neue Isoxazolderivate über 5-Amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl-und 5-Amino-4-cyano-3-trichlormethyl-isoxazol als Ausgangsverbindungen erhalten werden.

     

Highly regio- and stereoselective synthesis of tricyclic frameworks using Baylis-Hillman derivatives

A simple and convenient synthetic route for the synthesis of tricyclic chromeno[4,3-b]pyrrolidine frameworks using Baylis-Hillman bromides involving in situ formation of an imine, decarboxylation and a [3+2] cycloaddition sequence is described.     

Unexpected reactions of [60]fullerene involving tertiary amines and insight into the reaction mechanisms

Thermal reactions of [60]fullerene with amino acid ester hydrochlorides and triethylamine in o-dichlorobenzene at reflux afforded pyrrolidinofullerene derivatives containing the CH(3)CH moiety and originating from triethylamine through an unusual C-N bond cleavage. Detailed investigation of these thermal reactions resulted in the discovery of unprecedented reactions between C(60) and tertiary amines and of reactions of C(60) with tertiary amines and aldehydes, giving cyclopentafullerene derivatives with high stereoselectivity. Plausible reaction mechanisms for the product formation involving the uncommon C-N bond cleavage of tertiary amines were proposed on the basis of extensive experimental results.