Browsing by Author "Cheng, Chien-Hong"

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Fullerene Derivatives Incorporating Phosphoramidous Ylide and Phosphoramidate: Synthesis and Property
(2009-07-03)
Chen, Sheng-Yuan
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Cheng, Rai-Long
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Tseng, Cheng-Kuo
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Lin, Ya-Shiuan
;
Lai, Li-Hsiang
The reaction of dimethyl acetylenedicarboxylate (DMAD) with C(60) in the presence of hexamethylphosphorous triamide (HMPT) or hexaethylphosphorus triamide (HEPT) results in fullerene derivatives incorporating HMPT or HEPT ylides. The ylide derivatives exhibit unusual electronic absorptions in the visible region (435-660 nm), likely due to the presence of the ylide moiety. Electrochemical studies revealed that the first reductive potential of these compounds was more negative relative to those of both C(60) (Delta E = 130 mV) and a simple Bingel adduct (Delta E = 90 mV). A phosphoramidate side product, which resulted from the addition of HMPT or HEPT to C(60) followed by hydrolysis, exhibited a featureless absorption spectrum in the visible region and a more negative first reductive potential (Delta E = 70 mV) relative to that of C(60).
Impact of the Valence Charge of Transition Metals on the Cobalt- and Rhodium-Catalyzed Synthesis of Indenamines, Indenols, and Isoquinolinium Salts: A Catalytic Cycle Involving M-III/M-V [M = Co, Rh] for [4+2] Annulation
(2018-08-03)
Chiou, Mong-Feng
;
Jayakumar, Jayachandran
;
Cheng, Chien-Hong
;
Chuang, Shih-Ching
;
應用化學系
Reaction mechanisms for the synthesis of indenamines, indenols, and isoquinolinium salts through cobalt- and rhodium-catalysis were investigated using density functional theory calculations. We found that the valence charge of transition metals dramatically influences the reaction pathways. Catalytic reactions involving lower-oxidation-state transition metals (M-I/M-III, M = Co and Rh) generally favor a [3 + 2] cyclization pathway, whereas those involving higher oxidation states (M-III/M-V) proceed through a [4 + 2] cyclization pathway. A catalytic cycle with novel M-III/M-V as a crucial species was successfully revealed for isoquinolinium salts synthesis, in which highly valent M-V was encountered not only in the [RhCp*]-catalysis but also in the [CoCp*]-catalysis.
One pot synthesis of bioactive benzopyranones through palladium-catalyzed C-H activation and CO insertion into 2-arylphenols
(2013)
Lee, Tai-Hua
;
Jayakumar, Jayachandran
;
Cheng, Chien-Hong
;
Chuang, Shih-Ching
;
應用化學系
Palladium-catalyzed oxidative carbonylation of 2-arylphenols through C-H bond activation and C-C and C-O bond formation under acid-base free and mild conditions has been developed. The reaction tolerates a variety of substrates and provides biologically important benzopyranone derivatives in up to 87% isolated yield.
One-Pot Synthesis of Highly Substituted Polyheteroaromatic Compounds by Rhodium(III)-Catalyzed Multiple C-H Activation and Annulation
(2014-09-08)
Jayakumar, Jayachandran
;
Parthasarathy, Kanniyappan
;
Chen, Yi-Hsiang
;
Lee, Tai-Hua
;
Chuang, Shih-Ching
A new method for the synthesis of highly substituted naphthyridine-based polyheteroaromatic compounds in high yields proceeds through rhodium(III)-catalyzed multiple CH bond cleavage and CC and CN bond formation in a one-pot process. Such highly substituted polyheteroaromatic compounds have attracted much attention because of their unique -conjugation, which make them suitable materials for organic semiconductors and luminescent materials. Furthermore, a possible mechanism, which involves multiple chelation-assisted ortho CH activation, alkyne insertion, and reductive elimination, is proposed for this transformation.
Palladium-Catalyzed Selective Aryl Ring C-H Activation of N-Acyl-2-aminobiaryls: Efficient Access to Multiaryl-Substituted Naphthalenes
(2016-11-17)
Annamalai, Pratheepkumar
;
Chen, Wu-Yin
;
Raju, Selvam
;
Hsu, Kou-Chi
;
Upadhyay, Nitinkumar Satyadev
Palladium-catalyzed cycloaromatization of N-acyl-2-aminobiaryls, through a sequence of ortho C-H bond activation/alkyne insertion/meta C-H bond activation/alkyne insertion, was developed. An efficient synthesis of multiaryl-substituted naphthalenes, N-[2-(5,6,7,8-tetraarylnaphthalen-1-yl) aryl] acetamides, was demonstrated using molecular oxygen as the sole oxidant. Furthermore, through Buchwald\'s synthetic protocol, two compounds were converted into corresponding fluorescent carbazoles in 30-40% yield by intramolecular C-N bond formation.