Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
作者:Fernando Portela-Cubillo、James Lymer、Eoin M. Scanlan、Jackie S. Scott、John C. Walton
DOI:10.1016/j.tet.2008.08.112
日期:2008.12
an atom-efficient way of generating iminylradicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their CN 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 iminylradicals that ring closed to afford 3,4-dihydro-2H-pyrroles
From dioxime oxalates to dihydropyrroles and phenanthridines via iminyl radicals
作者:Fernando Portela-Cubillo、Eoin M. Scanlan、Jackie S. Scott、John C. Walton
DOI:10.1039/b808625g
日期:——
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.
cascade manner with an aminative cyclization triggered by N−O bond cleavage of an alkene‐tethered oxime ester. Various arenes, including electron‐rich and electron‐poor arenes, and heteroarenes can be employed in the reaction system. Regioselectivity and radical trapping experiments support the involvement of alkyl radical species, which undergo a homolytic aromatic substitution (HAS) to afford the
Pyrroline Synthesis via Visible-Light-Promoted Hydroimination of Unactivated Alkenes with <i>N</i>
,<i>N′</i>
-Dimethylpropylene Urea as <i>H</i>
-Donor
Synthesis of 3,4‐pyrroline derivatives via visible‐light‐induced hydro/oxyimination of unactivated olefins is reported. In the presence of the photoredox catalyst fac‐Ir(ppy)3, the key iminyl radical intermediate can be readily generated from O‐acyl oximes, and undergoes intramolecular cyclization and H‐abstraction from solvent or is trapped by TEMPO to give the corresponding hydro/oxyimination product