Cycloaddition: Difference between revisions

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Revision as of 08:41, 19 January 2016

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===Iron-catalyzed 2+2 olefin cycloaddition===

Iron[pyridine(diimine)] catalysts contain a redox active ligand in which the central iron atom can coordinate with two simple, unfunctionalized olefin double binds. The catalyst can be written as a resonance between a structure containing unpaired electrons with the central iron atom in the II oxidation state, and one in which the iron is in the 0 oxidation state. This gives it the flexibility to engage in binding the double bonds as they undergo a cyclization reaction, generating a cyclobutane structure via C-C reductive elimination; alternatively a cyclobutene structure may be produced by beta-hydrogen elimination. Efficiency of the reaction varies substantially depending on the alkenes used, but rational ligand design may permit expansion of the range of reactions that can be catalyzed.<ref>{{cite journal|title=Iron-catalyzed intermolecular [2+2] cycloadditions of unactivated alkenes|author=Jordan M. Hoyt, Valeria A. Schmidt, Aaron M. Tondreau, Paul J. Chirik|journal=Science|date=2015-08-28|volume=240349|issue=6251|pages=960-963}}</ref><ref>{{cite journal|title=As simple as [2+2]|author=Myles W. Smith and Phil S. Baran|journal=Science|date=2015-08-28|volume=240349|issue=6251|pages=925-926}}</ref>

===Cheletropic reactions===