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Browsing by Author "Tsai, Chung-Yu"

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    Nickel-mediated cross-coupling via C-O activation assisted by organoaluminum
    (1970-01-01)
    Liu, Cheng-Yuan
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    Wititsuwannakul, Taveechai
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    Hsieh, Chu-Han
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    Tsai, Chung-Yu
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    Wang, Ting-Hsuan
    We report the alkylation and arylation cross-coupling of aryl ethers based on C-O bond activation using a nickel catalyst and organoaluminum reagents. Ni(cod)(2) in combination with 1,2-bis(dicyclohexylphosphino)ethane ligand in toluene solution at 130 degrees C are the best conditions. The naphthyl ether or methoxy pyridine derivatives are suitable substrates for alkylation and arylation reaction with a wider scope of aluminum reagents in good yields. Computational analysis on the pyridine substrate is provided to help delineate the mechanistic pathway and demonstrate the important aspects of the cooperative interaction bimetallic catalysis. First, the coordination of AlMe3 to the O atom of pyridine is essential for C-O activation. Second, the beta-H transfer from methoxy to pyridine could be discouraged through the use of bidentate phosphine as a ligand. Finally, excess AlMe3 reagent is critical for facilitating a reductive elimination process.
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    One-Pot Tandem Photoredox and Cross-Coupling Catalysis with a Single Palladium Carbodicarbene Complex
    (2018-04-16)
    Hsu, Yu-Cheng
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    Wang, Vincent C. -C.
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    Au-Yeung, Ka-Chun
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    Tsai, Chung-Yu
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    Chang, Chun-Chi
    The combination of conventional transition-metal-catalyzed coupling (2e(-) process) and photoredox catalysis (1e(-) process) has emerged as a powerful approach to catalyze difficult cross-coupling reactions under mild reaction conditions. Reported is a palladium carbodicarbene (CDC) complex that mediates both a Suzuki-Miyaura coupling and photoredox catalysis for C-N bond formation upon visible-light irradiation. These two catalytic pathways can be combined to promote both conventional transition-metal-catalyzed coupling and photoredox catalysis to mediate C-H arylation under ambient conditions with a single catalyst in an efficient one-pot process.