848245-36-3Relevant academic research and scientific papers
Mechanisms of allene stereoinversion by imidozirconium complexes
Michael, Forrest E.,Duncan, Andrew P.,Sweeney, Zachary K.,Bergman, Robert G.
, p. 7184 - 7185 (2003)
The zirconium-mediated stereoinversion of allenes has been investigated by studying the stereochemical behavior of metallacycles derived from [2+2] cycloaddition of enantioenriched allenes with chiral and achiral imidozirconocene complexes. Relative rates of metallacycle racemization were measured by circular dichroism, and intermediates in the selective stereoinversion of diphenylallene with a chiral imidozirconium complex were observed by NMR spectroscopy. Metallacycles derived from dialkylallenes are proposed to racemize via reversible β-hydride elimination. Stereoinversion of diarylallene-derived metallacycles proceeds much more slowly and is thought to proceed through an η4-azatrimethylenemethane transition state. Copyright
Rearrangements and stereomutations of metallacycles derived from allenes and imidozirconium complexes
Michael, Forrest E.,Duncan, Andrew P.,Sweeney, Zachary K.,Bergman, Robert G.
, p. 1752 - 1764 (2007/10/03)
The mechanisms of the rearrangements and Stereoinversion of azametallacyclobutenes generated via [2+2] cycloaddition of allenes and imidozirconium complexes have been studied. Metallacycles derived from allenes bearing β-hydrogen atoms racemize at room temperature by reversible β-hydride elimination, a process which is also responsible for their eventual conversion to monoazadiene complexes. Metallacycles derived from diarylallenes racemize by reversible thermal bond homolysis at 95°C; racemization of these metallacycles is also catalyzed by mild oxidants.
