Ligand-Enhanced Aliphatic Carbon−Carbon Bond Activation of Nitroxides by Rhodium(II) Porphyrin
摘要:
Rh(tmp) underwent Ph3P-enhanced aliphatic carbon carbon bond activation with various nitroxides. (Ph3P)Rh(tmp), rapidly formed from Rh(tmp) and Ph3P, enhanced the rate, selectivity, and yield in comparison to Rh(tmp). From kinetic studies, the rate of reaction showed a first-order dependence on both Rh(tmp) and TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl) and saturation kinetics on Ph3P. The rate enhancement of (Ph3P)Rh(tmp) over Rh(tmp) was estimated to be about 11 at 70 degrees C.
Re-formation Reaction of Cyclic Nitroxide-Based Alkoxyamines: Steric and Polar/Stabilization Effects
作者:Hanns Fischer、Sylvain R. A. Marque、Peter Nesvadba
DOI:10.1002/hlca.200690217
日期:2006.10
are of considerable interest, but up to now, the polar/stabilization effects have not been addressed thoroughly. The combination of new data with previously reported data now showed that the re-formation rate constant kc increases with the increasing polar character of the substituents attached to the nitroxide moiety. The polar/stabilization effects are weaker for the re-formation than for the homolysis