Browsing by Author "Chiou, Mong-Feng"

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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.
Multicomponent reactions of phosphines, enynedioates and benzylidene malononitriles generated highly substituted cyclopentenes through an unexpected phosphine alpha-addition-delta-evolvement of an anion pathway
(2016)
Chuang, Shih-Ching
;
Sung, Shih-Ping
;
Deng, Jie-Cheng
;
Chiou, Mong-Feng
;
Hsu, Day-Shin
Multicomponent reactions of phosphines, enynedioates and benzylidene malononitriles provide highly substituted syn-selective cyclopentenes appending the phosphorus ylide moiety in good yield with a diastereoselectivity of up to 100% through resonance-derived 1,5-dipolar species as the key intermediates, via the nucleophilic alpha(delta\')-attack of phosphines toward enynedioates followed by addition to benzylidene malononitriles and 5-exo-dig cyclization. Through computational analyses, the overall reactions for the formation of syn- and anti-diastereomers are both exothermic with 65.6 and 66.3 kcal mol(-1) at the B3LYP-D3/6-31G(d) level of theory and were found to be kinetically controlled, which favours the formation of syn-diastereomers.