Browsing by Author "Jurca, Titel"

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Carbodicarbenes: Unexpected pi-Accepting Ability during Reactivity with Small Molecules
(2017-09-13)
Chen, Wen-Ching
;
Shih, Wei-Chih
;
Jurca, Titel
;
Zhao, Lili
;
Andrada, Diego M.
An investigation of carbodicarbenes, the less explored member of the carbenic complex/ligand family has yielded unexpected electronic features and concomitant reactivity. Observed 1,2-addition of E-H bonds (E = B, C, Si) across the carbone central carbon and that of the flanking N-heterocyclic carbene (NHC) fragment, combined with single-crystal X-ray studies of a model Pd complex strongly suggests a significant level of pi-accepting ability at the central carbon of the NHC moiety. This feature is atypical of classic NHCs, which are strong sigma-donors, with only nominal pi-accepting ability. The unanticipated pi-acidity is critical for engendering carbodicarbenes with reactivity more commonly observed with frustrated Lewis pairs (FLPs) rather than the more closely related NHCs and cyclic (alkyl)(amino)carbenes (CAACs).
Expanding the Ligand Framework Diversity of Carbodicarbenes and Direct Detection of Boron Activation in the Methylation of Amines with CO2
(2015-12-07)
Chen, Wen-Ching
;
Shen, Jiun-Shian
;
Jurca, Titel
;
Peng, Chun-Jung
;
Lin, Yen-Hsu
A simple and convergent synthetic strategy used to increase the diversity of the carbodicarbene ligand framework through incorporation of unsymmetrical pendant groups is reported. Structural analysis and spectroscopic studies of ligands and their Rh complexes are reported. Reactivity studies reveal carbodicarbenes as competent organocatalysts for amine methylation using CO2 as a synthon. A unique B-H-activated boron-carbodicarbene complex was isolated as a reaction intermediate, providing mechanistic insight into the CO2 functionalization process.
Expanding the Ligand Framework Diversity of Carbodicarbenes and Direct Detection of Boron Activation in the Methylation of Amines with CO2
(2015-12-07)
Chen, Wen-Ching
;
Shen, Jiun-Shian
;
Jurca, Titel
;
Peng, Chun-Jung
;
Lin, Yen-Hsu
A simple and convergent synthetic strategy used to increase the diversity of the carbodicarbene ligand framework through incorporation of unsymmetrical pendant groups is reported. Structural analysis and spectroscopic studies of ligands and their Rh complexes are reported. Reactivity studies reveal carbodicarbenes as competent organocatalysts for amine methylation using CO2 as a synthon. A unique B-H-activated boron-carbodicarbene complex was isolated as a reaction intermediate, providing mechanistic insight into the CO2 functionalization process.
Nickel Carbodicarbene Catalyzes Kumada Cross-Coupling of Aryl Ethers with Grignard Reagents through C-O Bond Activation
(1970-01-01)
Ambre, Ram
;
Yang, Hsuan
;
Chen, Wen-Ching
;
Yap, Glenn P. A.
;
Jurca, Titel
The development of a cross-coupling reaction protocol between aryl ethers and Grignard reagents catalyzed by carbodicarbene (CDC) nickel complexes to afford biaryl compounds through C-O cleavage is reported. Aromatic substrates featuring a broad range of electron neutral, donating, or withdrawing groups are introduced at the desired position. The method has proven effective over a wide range of naphthyl methyl ethers, anisoles, and Grignard reagents. The robustness of the protocol is validated by performing multiple cleavage reactions, gram scale synthesis, and arylation of a dimethoxy esterdiol derivative.
One-Pot Tandem Photoredox and Cross-Coupling Catalysis with a Single Palladium Carbodicarbene Complex
(2018-04-16)
Hsu, Yu-Cheng
;
Wang, Vincent C. -C.
;
Au-Yeung, Ka-Chun
;
Tsai, Chung-Yu
;
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.