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제124회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Transition Metal-Catalyzed Alkyne Functionalization for Use in Organic Synthesis

2019년 8월 23일 00시 02분 32초
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금 09시 : 00분
Organic Chemistry - Current Trends in Organic Chemistry I: Synthetic Methodology and Catalysis
저자 및
Chulbom Lee
Division of Chemistry, Seoul National University, Korea
Transition metals interact with alkynes to form σ-alkynyl, π-alkyne and vinylidene complexes that exist in dynamic equilibrium with one another. Our laboratory has been engaged in the development of new synthetic methods that make use of alkynes via mechanisms involving a metal vinylidene as a catalytic intermediate. A diverse array of new reactions has been developed, including enyne cycloisomerizations, and various processes effecting hydrative, alkylative, and carboxylative cyclizations. Recently, in a departure from these C-C bond-forming cyclizations, our explorations have been focused on the oxygen-transfer to the metal-bound carbene intermediate. This approach has led to discovery of alkyne oxygenation that occurs through the intermediacy of a metalloketene arising from catalytic oxidation of the metal vinylidene. Discussed in this presentation will be the design, implementation and mechanistic studies of the metal vinylidene-mediated catalytic oxidative reactions of alkynes. Also presented will be a tandem addition–cyclization–rearrangement process, where alkyne- tethered hydrazones react with organoboronic acids to give cycloalkene products in a traceless fashion. The cascade reaction is based on merger of pericyclic rearrangement and transition metal mediated catalysis making use of a π-alkyne intermediate. The novel process can also be performed with enantiocontrol. Employing a chiral diene ligand for the rhodium catalyst, the reaction provides cycloalkenes with an exo stereocenter in high enantioselectivity.