Selective zirconocene -Mediated Carbon-Carbon Bond Cleavage of
Alkylidenecyclopropanes: A New Approach to Enantiomerically Pure AllCarbon Quaternary Stereocenters
Ahmad. Masarwa and Ilan Marek*
Schulich Faculty of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum
Chemistry. Technion – Israel Institute of Technology, Haifa 32000 Israel
E-mail: chilanm@tx.technion.ac.il
Metal-catalyzed cleavage of carbon-carbon bonds is a field of current interest since it can lead
to the design of new, selective and efficient processes for the utilization of hydrocarbons.
Although the activation of C-C single bonds of strained three-membered rings is a known
process, the stereoselective carbon-carbon bond activation of alkylidenecyclopropanes (ACP),
through transition metal catalysts, have emerged only lately as an efficient tool for the synthesis
of functionalized linear products.1, 2
In this context, we have developed a new method that zirconocene-mediated ring opening of
alkylidenecyclopropane proceeds under mild condition through a combined CH allylic activation
reaction followed by a selective carbon-carbon bond cleavage to give the bismetallated allylalkyl zirconocene species that selectively react with two different electrophiles with high regioand diasteriosilictivity.3
The state of the art of these methodology would consist in the easy preparation of challenging
enantiomerically enriched saturated hydrocarbons with a quaternary stereogenic center such as
the simplest enantiomerically enriched (2S)-4-ethyl-4-methyl octane 1 and deuterated
neopentane 2. Current studies are ongoing for the preparation of these two species.3
1.
Masarwa, A.; Marek, I. Chem. Eur. J. 2010, 16, 9712.
2.
Marek, I.; Simaan, S.; Masarwa, A. Angew. Chem. Int. Ed., 2007, 46, 7364.
3.
Masarwa, A.; Marek, I. 2012. (Submitted)