A broadly applicable copper catalyst for photoredox transformations of organic halides is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF and an amine, a range of unactivated aryl and alkyl halides were shown to be smoothly activated through a rare Cu(I)/Cu(I)*/Cu(0) catalytic cycle. This complex efficiently catalyzes a series of radical processes, including reductions, cyclizations, and direct arylation of arenes.
A general anti-Baldwin radical 4-exo-dig cyclization from nitrogen-substituted alkynes is reported. Upon reaction with a heteroleptic copper complex in the presence of an amine and under visible light irradiation, a range of ynamides were shown to smoothly cyclize to the corresponding azetidines, useful building blocks in natural product synthesis and medicinal chemistry, with full control of the regioselectivity of the cyclization resulting from a unique and underrated radical 4-exo-dig pathway.
A set of two broadly applicable procedures for the N-arylation of hydantoins is reported. The first one relies on the use of stoichiometric copper(I) oxide under ligandand base-free conditions and enables a clean regioselective arylation at the N 3 nitrogen atom, while the second one is based on the use of catalytic copper(I) iodide and trans-N,N′-dimethylcyclohexane-1,2-diamine and promotes arylation at the N 1 nitrogen atom. Importantly, the combination of these two procedures affords a straightforward entry to diarylated hydantoins.
An efficient and highly practical procedure is reported for the Ullmann–Goldberg‐type copper‐catalyzed amination of aryl iodides. By using a combination of copper iodide and proline in the presence of an excess of an amine, a wide range of aryl iodides can be readily aminated at room temperature. The reaction proceeds well regardless of the electronic properties of the starting aryl iodide and the amination products can be obtained without the need for purification by column chromatography in most cases. Owing to its efficiency and the mildness of the reaction conditions, this amination could also be extended to the amination of complex aryl iodides at room temperature.
A general and efficient procedure for the copper-catalyzed photoinduced radical domino cyclization of ynamides and cyanamides providing an efficient access to complex tri-, tetra- and pentacyclic nitrogen heterocycles is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF6 and an amine, a range of unactivated aryl and alkyl iodides were shown to be smoothly transformed to the corresponding radical species, initiating the radical domino cyclization. This procedure provides a unified entry to rosettacin, luotonin A, and deoxyvasicinone that could be efficiently prepared in a limited number of steps.
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