Selective monofunctionalization was investigated for symmetrical zirconacyclopentanes or symmetrical dialkylzirconocenes. Reaction of zirconacyclopentanes, which were prepared by intermolecular coupling of two alkenes, or intramolecular cyclization of dienes, trienes or tetraenes on zirconium, with PPh2Cl or SnR3Cl (R = Me, Ph) gave monofunctionalized products in good to high yields with high selectivities. Even in the presence of 2 equiv. of PPh2Cl or SnR3Cl, only one Zr-carbon bond reacted. Treatment of zirconacyclopentanes with methanol yielded monoprotonated complexes. Subsequent addition of halogen such as Br2 and I2 to these monoprotonated complexes gave highly selective monohalogenated products. Similar monoprotonation reactions proceeded for dialkylzirconocene or-hafnocene complexes. Reaction of Cp2MR2 (M = Zr or Hf, R = alkyl or aryl) with alcohols afforded alkylalkoxyzirconocene or -hafnocene complexes, Cp2MR(OR′) (M = Zr or Hf, R′ = alkyl or aryl) in high yields with high selectivities. High selectivity of monofunctionalization using PPh2Cl, SnR3Cl or alcohols can be attributed to the different reactivities between monoalkylzirconocenes which are monofunctionalized products and zirconacyclopentanes or dialkylzirconocenes.
- Crystal structures
- Dialkylzirconocene complex
- Zirconacyclopentane complexes
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry