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Synlett 1999; 1999(7): 1179
DOI: 10.1055/s-1999-5734
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Zirconocene Hydrochloride "Schwartz Reagent"

Eduardo Fernández-Megía*
  • *Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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Publication Date:
31 December 1999 (online)

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Zirconocene Hydrochloride (Cp2ZrHCl, 1) also known as "Schwartz reagent", in a solid with low solubility in commonly used organic solvents. Carbon-carbon multiple bonds insert into the Zr-H bond of 1 is a syn fashion to give alkyl and E-alkenylzirconocenes (2) where the Zr is attached to the less hindered carbon atom. The polarization of the Zr-C bond in 2 is comparable to Grignard reagents, however, due to steric crowding around the Zr atom, only reaction with CO, isonitriles and halogen sources can be effected directly. Transmetallations (mostly to Al, Zn, Pd, B, Cu and Ni) are also possible to give new organometallics which are synthetically useful in other carbon-carbon bond forming reactions.

The rate of hydrozirconation decreases from terminal alkyne > terminal alkene ≉ internal alkyne > disubstituted alkene.