- Direct C(sp3)?H Trifluoromethylation of Unactivated Alkanes Enabled by Multifunctional Trifluoromethyl Copper Complexes
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A mild and operationally simple C(sp3)?H trifluoromethylation method was developed for unactivated alkanes by utilizing a bench-stable CuIII complex, bpyCu(CF3)3, as the initiator of the visible-light photoinduced reaction, the source of a trifluoromethyl radical as a hydrogen atom transfer reagent, and the source of a trifluoromethyl anion for functionalization. The reaction was initiated by the generation of reactive electrophilic carbon-centered CF3 radical through photoinduced homolytic cleavage of bpyCu(CF3)3, followed by hydrogen abstraction from an unactivated C(sp3)?H bond. Comprehensive mechanistic investigations based on a combination of experimental and computational methods suggested that C?CF3 bond formation was enabled by radical–polar crossover and ionic coupling between the resulting carbocation intermediate and the anionic CF3 source. The methylene-selective reaction can be applied to the direct, late-stage trifluoromethylation of natural products and bioactive molecules.
- Choi, Geunho,Lee, Geun Seok,Park, Beomsoon,Kim, Dongwook,Hong, Soon Hyeok
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supporting information
p. 5467 - 5474
(2021/01/20)
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- Csp3-H Trifluoromethylation of Unactivated Aliphatic Systems
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A straightforward method for the undirected trifluoromethylation of unactivated methylene units was developed. The reaction proceeds in aqueous acetonitrile with Grushin's reagent, bpyCu(CF3)3, under broad-spectrum white-light irradiation. The trifluoromethylation tolerates a wide range of functional groups including ketones, esters, nitriles, amides, alcohols, and carboxylic acids. The C-H cleavage step is performed via intermolecular H atom abstraction, and the selectivities across a range of methylene units are reported. Mechanistic studies offer a general reaction coordinate for the overall transformation.
- He, Jiachen,Nguyen, Truong N.,Guo, Shuo,Cook, Silas P.
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supporting information
p. 702 - 705
(2021/02/01)
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- Pyrazolo[3,4-b]pyridine carboxylic acid esters and their pharmaceutical use
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Compounds of the formula (I): STR1 wherein R1, R3, R4, R5 and R6 have defined values and the N-oxides at the 7-position of the pyrazolo[3,4-b]pyridine ring system and the pharmaceutically-acceptable acid-addition salts thereof, processes for their preparation and use, pharmaceutical compositions, and intermediates for preparing said compounds of the formula (I). The compounds of formula (I) are central nervous system depressants, for example anxiolytic agents.
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