Zirconium Mediated Regioselective Carbon-Carbon Bond Formation Reactions

Abstract

Reactions of zirconocene-alkene complexes with aldehydes gave alcohols as coupling products after hydrolysis. The carbon-carbon bond formation proceeded at C1 carbon of alkenes, in sharp contrast to the reactions of alkene-alkene coupling on zirconium. A similar alcohol was also obtained by the reaction of zirconacyclopentane with aldehyde after hydrolysis. Treatment of (C5Me5)2ZrEt2 with styrene gave 2-phenylbutane after hydrolysis contrary to the case of Cp2ZrEt2 which afforded 1-phenylbutane.

Stable rac-[1,2-Ethylene-1,1‘-bis(η5-tetrahydroindenyl)]- zirconacyclopentanes. Syntheses, X-ray Crystal Structures, Stability, and Catalysis of Ethylene Polymerization

“…The regioselectivity of the olefin-olefin coupling reactions was found to depend on steric and electronic interactions. Electronically, the α-position is favored, while the repulsion between the tetrahydroindenyl ligand and the phenyl residue should lead to a preferred occupation of the β-position as found in similar Cp*Zr complexes.…”

Synthesis of Hafnacyclopentanes from Hafnocene Alkyne Complexes: Influence of Styrene Substituents on the C–C Coupling Regioselectivity

“…[8] The substituent in the β-position avoids steric hindrance by interaction with the ebthi ligand. [9] Figure 1. Molecular structure of complex 2.…”

Transition‐Metal‐Catalyzed Laboratory‐Scale Carbon–Carbon Bond‐Forming Reactions of Ethylene

“…Sterically hindered, non-enolizable aldehydes work best, including those leading to 29a – d , and a wide variety of alkyl silyl triflates are well tolerated. Despite pre-existing examples utilizing stoichiometric amounts of transition metals, [22] this was the first example of a catalytic intermolecular coupling of ethylene to aldehydes. The mechanism was proposed to involve an initial cyclometallation of ethylene and the aldehyde with nickel(0), with subsequent Lewis acid activation of the alkoxide, and finally b-hydride elimination.…”