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Stereoselective Preparation of Dienyl Zirconocene Complexes via a Tandem Allylic C−H Bond Activation-Elimination Sequence

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journal contribution
posted on 02.10.2003, 00:00 by Nicka Chinkov, Swapan Majumdar, Ilan Marek
Several dienyl zirconocene derivatives were easily prepared, as unique geometrical isomers, from simple non-conjugated unsaturated enol ethers with (1-butene)ZrCp2 complexes. This new methodology is based on a tandem allylic C-H bond activation-elimination sequence and the mechanism has been mapped out by deuterium labeling experiments. The stereochemical outcome of this process was determined by addition of several electrophiles. Moreover, when the organometallic derivative is vinylic as well as allylic such as in 4447Zr, an unexpected reversal of the stereochemistry has been found during the zirconium to copper transmetalation step.