1,2-Bis-perfluoroalkylations of alkenes and alkynes with perfluorocarboxylic anhydrides via the formation of perfluoroalkylcopper intermediates.

A novel, Cu-mediated protocol toward the 1,2-bis-perfluoroalkyaltion of alkenes/alkynes was developed. The method proceeded with perfluorocarboxylic anhydrides as inexpensive and readily available perfluoroalkyl sources. Diacyl peroxide was generated in situ from the perfluorocarboxylic anhydrides and H2O2. The key step in this reaction is the formation of a stable perfluoroalkylcopper intermediate that is achieved with the aid of a bipyridyl ligand. Subsequent reaction of the intermediate with perfluoroalkyl-containing alkyl or vinyl radicals affords the desired products.

Determination of acid dissociation constants of flavin analogues by capillary zone electrophoresis.

Acid dissociation constants (pKa ) of nine kinds of flavin analogues as molecular catalyst candidates were determined by CZE. Although some of the analogues are instable and degradable under the light exposure or in alkaline aqueous solutions, the effective electrophoretic mobility of the flavin analogue of interest has been measured with the residual substance. The pKa values of the flavin analogues were analyzed through the changes in the effective electrophoretic mobility with varying pH of the separation buffer. One or two steps pKa values were determined by the analysis. One of the degraded species from the flavin analogues, lumichrome, was also detected in the CZE analysis, and its pKa values were also determined. While coexisting impurities generated over the storage conditions were found in some analogues, the pKa values of the target analogues were successfully determined with the help of the CZE separations. A pressure-assisted CZE was utilized for the determination or the estimation of the pKa values of such analogues as possessing carboxylic acid moiety.

Efficient Use of Photons in Photoredox/Enamine Dual Catalysis with a Peptide-Bridged Flavin-Amine Hybrid.

An isoalloxazine (flavin) ring system and a secondary amine have been integrated through a short peptide linker with the aim of using photons as efficiently as possible in photoredox/enamine dual catalysis. We herein report a peptide-bridged flavin-amine hybrid that can catalyze α-oxyamination of aldehydes with TEMPO under weak blue light irradiation to achieve an extremely high quantum yield of reaction (Φ = 0.80).