Browsing by Author "Rajeshkumar, Venkatachalam"

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[3+2] Cycloaddition of Dialkyl (E)-Hex-2-en-4-ynedioates to [60]Fullerene by Phosphane-Promoted Tandem alpha(delta ')-Michael Additions
(2012-05-01)
Chuang, Shih-Ching
;
Deng, Jie-Cheng
;
Chan, Fu-Wei
;
Chen, Sheng-Yuan
;
Huang, Wei-Je
Organophosphanes promote the [3+2] cycloaddition reactions of dialkyl (E)-hex-2-en-4-ynedioates and [60]fullerene, giving a series of cyclopenteno-fullerenes 3ak bearing phosphorus ylides. This cycloaddition reaction is initiated by the attack of nucleophilic phosphanes at the a(d')-C atom of the dialkyl (E)-hex-2-en-4-ynedioate, which generates a 1,3-dipolar species. These 1,3-dipoles then react with C60 followed by intramolecular cyclization to give cyclopenteno-fullerenes in moderate-to-good yields. In a cyclic voltmmetry study, these novel fullerenes show a larger cathodic shift in their first reduction potential relative to [6,6]phenyl-C61 methyl butyrate, which indicates that these new derivatives possess higher LUMO energy levels.
Annulation of Benzamides with [60]Fullerene through Palladium(II)-Catalyzed C-H Bond Activation
(2011-03-18)
Chuang, Shih-Ching
;
Rajeshkumar, Venkatachalam
;
Cheng, Chun-An
;
Deng, Jie-Cheng
;
Wang, Guan-Wu
Palladium-catalyzed heteroannulation of N-substituted benzamides with [60]fullerene, which proceeds through direct sp(2) C-H bond activation to form 7-membered ring pallada-intermediate with C(60), led to formation of [60]fulleroisoquinolinones in moderate to good yields (8-64% based on recovered C(60)). A plausible reaction pathway is proposed.
Evolution of Late Transition-Metal-Catalyzed Intermolecular Reductive Coupling Reaction of [60]Fullerene and N-Sulfonylaldimines: Competing Formation of Hydrobenzylated [60]Fullerenes and 1,2-Dihydrofullerene
(2012-07-01)
Rajeshkumar, Venkatachalam
;
Chuang, Shih-Ching
;
應用化學系
;
Department of Applied Chemistry
A system based on late transition-metal halides, phosphanes, water, and reducing agents in 1,2-dichlorobenzene can efficiently catalyze the intermolecular reductive coupling of [60]fullerene with N-sulfonylaldimines to afford novel 1,2-hydrobenzylated [60]fullerene derivatives. We found that both group VII?B metals (cobalt, rhodium, iridium) and group VIII?B metals (nickel, palladium, platinum) perform this coupling reaction. A control experiment in the absence of aldimines produced C60H2, which showed that the reaction might proceed via a [60]fullerene metal complex [M(?2-C60)(ligand)]. An isotope labeling experiment with D2O as deuterium source resulted in deuterioaryzilation with deuterium bonded to the sp3-carbon of C60, providing evidence of a five-membered azametallacycle intermediate. Evaluation of the scope of reductive coupling reaction with versatile aldimines gave access to the hydroaryzilation products. All the reductive coupling products were completely characterized by IR and NMR spectroscopy and ESI mass spectrometry. A possible reaction mechanism based on these results is proposed. This discovery of the formation of reductive coupling compounds and metal-catalyzed formation of C60H2 are both new to metal catalysis and fullerene chemistry.
Palladium-Catalyzed and Hybrid Acids-Assisted Synthesis of [60]Fulleroazepines in One Pot under Mild Conditions: Annulation of N-Sulfonyl-2-aminobiaryls with [60]Fullerene through Sequential C-H Bond Activation, C-C and C-N Bond Formation
(2012-09-01)
Rajeshkumar, Venkatachalam
;
Chan, Fu-Wei
;
Chuang, Shih-Ching
;
應用化學系
;
Department of Applied Chemistry
An extraordinarily efficient hybrid acids-assisted, palladium-catalyzed and chelating-group-assisted C?H bond activation of N-sulfonyl-2-aminobiaryls and their annulations with [60]fullerene via sequential C?C and C?N bond formation at room temperature to afford [60]fulleroazepines is demonstrated. The formation of [60]fulleroazepines is highly regioselective and tolerant to both electron-withdrawing and electron-donating groups on the aryl moiety and the reaction gives monofunctionalized fullerenes in good yields (up to 54% isolated yield and 92% based on converted C60).
Palladium-Catalyzed Oxidative Insertion of Carbon Monoxide to N-Sulfonyl-2-aminobiaryls through C-H Bond Activation: Access to Bioactive Phenanthridinone Derivatives in One Pot
(2013-04-05)
Rajeshkumar, Venkatachalam
;
Lee, Tai-Hua
;
Chuang, Shih-Ching
;
應用化學系
;
Department of Applied Chemistry
Palladium-catalyzed oxidative carbonylation of N-sulfonyl-2-aminobiaryls through C-H bond activation and C-C, C-N bond formation under TFA-free and milder conditions has been developed. The reaction tolerates a variety of substrates and provides biologically important phenanthrldlnone derivatives in yields up to 94%.