- Electron-transfer-mediated synthesis of phenanthridines by intramolecular arylation of anions from n-(ortho-Halobenzyl)arylamines: regiochemical and mechanistic analysis
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The synthesis of a series of substituted phenanthridines by photostimulated C-C cyclization of anions from N-(orrAo-halobenzyl)arylamines has been found to proceed in very good to excellent yields (79-95%) in liquid ammonia and in DMSO. The N-(ortho-halobenzyl)arylamines are obtained in good to very good isolated yields (44-85%) by nucleophilic substitution of orthohalobenzylchlorides with different arylamines. The reaction of the anions of a diverse set N-(orthohalobenzyl)arylamines was studied, and the methodology was extended to the synthesis of trispheridine, a natural product, in very good yield, In order to explain the regiochemical outcome of these reactions, a theoretical analysis was performed with DFT methods and the B3LYP functional.
- Buden, Maria E.,Dorn, Viviana B.,Gamba, Martina,Pierini, Adriana B.,Rossi, Roberto A.
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experimental part
p. 2206 - 2218
(2010/06/17)
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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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