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
Kinetic and Theoretical Study of 4-<i>e</i><i>xo</i> Ring Closures of Carbamoyl Radicals onto CC and CN Bonds
作者:Gino A. DiLabio、Eoin M. Scanlan、John C. Walton
DOI:10.1021/ol047716+
日期:2005.1.1
Carbamoyl radicals were generated from oxime oxalate amides, and the kinetics of their 4-exo cyclizations onto C=C and C=NO bonds, leading to beta-lactam-containing species, were studied by EPR spectroscopy. DFT computations with model carbamoyl radicals predicted 4-exo ring closures onto C=NO bonds to be facile, especially when tert-butyl substituents were present. The reverse ring-opening reactions
Preparation and Beckmann Rearrangement of<i>O</i>-(Chlorooxalyl)oximes
作者:Johannes C. Jochims、Sabine Hehl、Siegfried Herzberger
DOI:10.1055/s-1990-27112
日期:——
Oximes 1 react with phosgene or oxalyl chloride to give O-(chloroformyl)- 2, or O-(chlorooxalyl) oximes 8, which undergo Beckmann rearrangement with antimony pentachloride to afford nitrilium hexachloroantimonates 3 in high yields. With di- or triphosgene (4 or 6) oximes 1 form mixtures of O-(chloroformyl)- 2 and O-(trichloromethoxyformyl)oximes 5. The O-(chlorooxalyl)oximes 8 further characterized as esters 10 and amides 11. With N,N-dimethylformamide the nitrilium salts 3 react to give N-acyl formamidinium salts 12.