In the past decades, the Cu-catalyzed asymmetric organic reactions have been well-developed. By contrast, the potential of Cu to serve as a chiral photocatalyst remains underexplored. We here report the visible-lightinduced, Cu-catalyzed photoredox enantioselective cyanofluoroalkylation of alkenes. In the reaction, the Cu-based single catalyst played a dual role, as both the photoredox catalyst for the outer-sphere electron transfer and the asymmetric cross-coupling catalyst for enantioselective C− CN bond formation.
The first visible-light-promoted dearomative fluoroalkylation of β-naphthols was realized without the assistance of any transition-metal catalysts or external photosensitizers. Inexpensive fluoroalkyl iodides were directly used as efficient fluoroalkylation reagents under very mild reaction conditions. The scope of this process was found to be general and broad, and both trifluoromethyl and perfluoroalkyl groups (-C F , -C F , and -C F ) were installed in excellent yields. Preliminary mechanistic studies suggest that visible-light-promoted intermolecular charge transfer within the naphtholate-fluoroalkyl iodide electron donor-acceptor (EDA) complex induces a single electron transfer in the absence of photocatalysts.
A mild, versatile, and convenient method for efficient intramolecular oxytrifluoromethylthiolation of unactivated alkenes catalyzed by Cu(OAc)2 has been developed. The reactions were carried out under aerobic conditions and formed a variety of isoxazolines bearing a -SCF3 substituent.
The C-N cross coupling reaction has always been a fundamental task in organic synthesis. However, the direct use of N-H group of aryl amines to generate N-centered radicals which would couple with alkyl radicals to construct C-N bonds is still rare. Here we report a visible light-promoted C-N radical cross coupling for regioselective amination of remote C(sp3)-H bonds. Under visible light irradiation, the N-H groups of aryl amines are converted to N-centered radicals, and are then trapped by alkyl radicals, which are generated from Hofmann-Löffler-Freytag (HLF) type 1,5-hydrogen atom transfer (1,5-HAT). With the same strategy, the regioselective C(sp3)-C(sp3) cross coupling is also realized by using alkyl Hantzsch esters (or nitrile) as radical alkylation reagents. Notably, the α-C(sp3)-H of tertiary amines can be directly alkylated to form the C(sp3)-C(sp3) bonds via C(sp3)-H − C(sp3)-H cross coupling through the same photoredox pathway.
C-H bond phosphorylation of ketene dithioacetals was achieved under transition-metal-free or AgNO3 mediated conditions. Synthetic transformations of the coupling product provided promising methods for the construction of highly functionalized phosphorylated N-heterocycles and tetrasubstituted alkenes.
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