Browsing by Author "Jayakumar, Jayachandran"

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Cascade One-Pot Synthesis of Orange-Red-Fluorescent Polycyclic Cinnolino[2,3-f]phenanthridin-9-ium Salts by Palladium(II)-Catalyzed C-H Bond Activation of 2-Azobiaryl Compounds and Alkenes
(1970-01-01)
Jayakumar, Jayachandran
;
Vedarethinam, Guganchandar
;
Hsiao, Huan-Chang
;
Sun, Shang-You
;
Chuang, Shih-Ching
Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C-H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2-azobiaryls with alkenes to give orange-red-fluorescent cinnolino[2,3-f]phenanthridin-9-ium salts and 15H-cinnolino[2,3-f]phenanthridin-9-ium-10-ide is proposed to involve ortho C-H olefination of the 2-azobiaryl compound with the alkene, intramolecular aza-Michael addition, concerted metalation-deprotonation (CMD), reductive elimination, and oxidation.
Cascade One-Pot Synthesis of Orange-Red-Fluorescent Polycyclic Cinnolino[2,3-f]phenanthridin-9-ium Salts by Palladium(II)-Catalyzed C-H Bond Activation of 2-Azobiaryl Compounds and Alkenes
(2020-01-07)
Jayakumar, Jayachandran
;
Vedarethinam, Guganchandar
;
Hsiao, Huan-Chang
;
Sun, Shang-You
;
Chuang, Shih-Ching
Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C-H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2-azobiaryls with alkenes to give orange-red-fluorescent cinnolino[2,3-f]phenanthridin-9-ium salts and 15H-cinnolino[2,3-f]phenanthridin-9-ium-10-ide is proposed to involve ortho C-H olefination of the 2-azobiaryl compound with the alkene, intramolecular aza-Michael addition, concerted metalation-deprotonation (CMD), reductive elimination, and oxidation.
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.
Low-toxic cycloplatinated polymer dots with rational design of acceptor comonomers for enhanced photocatalytic efficiency and stability
(2020-07-05)
Chang, Chih-Li
;
Lin, Wei-Cheng
;
Jia, Chuan-Yu
;
Ting, Li-Yu
;
Jayakumar, Jayachandran
By mimicking nature photosynthesis, a library of cycloplatinated polymer dots (Pdots) and pristine Pdots are presented and investigated the importance of selecting acceptor comonomers. A clear design strategy for the selection of acceptor comonomers of Pdots to achieve environmental-friendly, high efficiency, and long stability of photocatalytic reaction can be understood. The active PFTBTA-PtPy Pdots provide the excellent hydrogen evolution rates up to 7.34 +/- 0.82 mmol h(-1) g(-1) under a methanol-free solution and visible-light-driven system. MTT assay experiments confirm the use of the cycloplatinated Pdots as photocatalysts can minimize the toxicity, relative to the conventional approach that directly adding Pt into a solution system. Furthermore, the Pdots can be reactivated for hydrogen generation by the recycling process. The result proves that the use of cycloplatinated Pdots can not only enhance the HER efficiency and stability but also reduce the toxicity.
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.