Asymmetric alkene cycloalumination by AlEt3, catalyzed with neomenthylindenyl zirconium η5-complexes

Article abstract of DOI:10.1016/j.jorganchem.2012.10.021

The paper is devoted to a study of the reaction of terminal alkene cycloalumination by AlEt₃ catalyzed with neomenthylindenyl zirconium complexes (p-S)(p-S)-bis[η⁵-[1-[(1S,2S,5R)-2-isopropyl-5- methylcycloh-exyl]indenyl]]zirconium dichloride (1) or (p-S)-(η⁵- cyclopentadienyl)[η⁵-[1-[(1S,2S,5R)-2-isopropyl-5- methylcyclohexyl]indenyl]]zirconium dichloride (2). It was shown that alkene and catalyst structures, as well as solvent, affect the overall yield and enantiomeric excess of the reaction product - 3-alkylsubstituted aluminacyclopentanes. The reaction of terminal alkenes with AlEt₃, catalyzed by complex 1, in hydrocarbon solvents gives predominantly S-enantiomers of cyclic organoaluminum compounds with enantiomeric excess up to 37%. Complex 2 shows smaller stereoinduction effect and provides R-enantiomers of aluminacyclopentanes with 6-26%ee. The effectiveness of selenium-containing derivatizing reagent (R)-2-phenylselenopropanoic acid for the enantiomeric excess estimation in β-alkyl-1,4-butanediols obtained from cyclic organoaluminum compounds was shown.