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
were used in situ to promote the asymmetric selenocyclization of γ-alkenyl oximes and δ-phenyl-γ-alkenyl oximes. The course of these reactions and hence the structures of the cyclization products were dictated by the (E)- or (Z)-geometry of the starting oximes. The two types of cyclization products were either the cyclicnitrones or the 1,2-oxazines; in both cases the reactions proceeded with excellent
Compositions and methods for inhibiting vinyl aromatic monomer polymerization
申请人:BETZ EUROPE, INC.
公开号:EP0690117A2
公开(公告)日:1996-01-03
Compositions and methods for inhibiting polymerization of vinyl aromatic monomers in oxygen-free processing systems are disclosed. The compositions comprise an oxime compound and a hydroxylamine compound and, alternatively, an oxime compound or a dinitrophenol, a hydroxylamine compound and a phenylenediamine compound. The methods comprise adding one of the compositions to the vinyl aromatic monomer in an amount ranging from 1 to about 10,000 parts per million parts monomer. An improved method for inhibiting the polymerization of vinyl aromatic monomers with a hydroxylamine compound is also disclosed. The improvement provides for adding a catalytic amount of a phenylenediamine compound to the vinyl aromatic monomer system while replacing any phenylenediamine compound lost as a result of physical removal from the system via the waste stream.
A new method for the generation and capture of iminylradicals
作者:Jean Boivin、Anne-Marie Schiano、Samir Z. Zard、Haiwen Zhang
DOI:10.1016/s0040-4039(99)00720-0
日期:1999.6
Iminyl radicals can be generated from ketoxime eaters and captured by an internal olefin; the sequence may be terminated in a variety of ways depending on the nature of the ensuing carbon radical and the added external trap. (C) 1999 Elsevier Science Ltd. All rights reserved.