Scope In one study the usual regioselectivity of an alkyne hydrozirconation is reversed with the addition of zinc chloride: One example of a one-pot hydrozirconation - carbonylation - coupling is depicted below: With certain allyl alcohols, the alcohol group is replaced by nucleophilic carbon forming a cyclopropane ring: The selectivity of the hydrozirconation of alkynes has been studied in detail. Generally, the addition of the Zr–H proceeds via the syn-addition. The rate of addition to unsaturated carbon-carbon bonds is terminal alkyne > terminal alkene ≈ internal alkyne > disubstituted alkene Acyl complexes can be generated by insertion of CO into the C–Zr bond resulting from hydrozirconation. Upon alkene insertion into the zirconium hydride bond, the resulting zirconium alkyl undergoes facile rearrangement to the terminal alkyl and therefore only terminal acyl compounds can be synthesized in this way. The rearrangement most likely proceeds via β-hydride elimination followed by reinsertion. Further reading References External links Examples in organic synthesis at the University of Connecticut website Metallocenes Organozirconium compounds Cyclopentadienyl complexes Reagents for organic chemistry Chloro complexes Metal hydrides Zirconium(IV) compounds