- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
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supporting information
p. 1653 - 1665
(2021/06/17)
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- Palladium-Catalyzed Enantioselective Narasaka–Heck Reaction/Direct C?H Alkylation of Arenes: Iminoarylation of Alkenes
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A palladium-catalyzed reaction of γ,δ-unsaturated oxime esters with oxadiazoles afforded dihydropyrroles in good to excellent yields through an intramolecular iminopalladation/intermolecular direct heteroarene C?H alkylation cascade. This unprecedented iminoarylation of alkenes was subsequently realized in an enantioselective manner in the presence of a chiral bidentate phosphine ligand (Synphos).
- Bao, Xu,Wang, Qian,Zhu, Jieping
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p. 9577 - 9581
(2017/08/01)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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scheme or table
p. 11908 - 11916
(2009/04/06)
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- From dioxime oxalates to dihydropyrroles and phenanthridines via iminyl radicals
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Dioxime oxalates are useful precursors for the clean generation of iminyl radicals by sensitised UV photolysis and can be adapted for serviceable preparations of 3,4-dihydro-2H-pyrroles and phenanthridines. The Royal Society of Chemistry.
- Portela-Cubillo, Fernando,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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experimental part
p. 4189 - 4191
(2009/03/11)
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