1070-00-4Relevant articles and documents
Synthesis of trialkylaluminum derivatives by the reaction of non-solvated aluminum hydride with α-olefins
Gavrilenko
, p. 1161 - 1163 (2003)
Hydroalumination of α-olefins by non-solvated polymeric aluminum hydride (AlH3)n occurs at 120-140°C. Mechanochemical activation accelerates this reaction. The addition of catalytic amounts of the prepared R3Al forms to the reaction system decreases the temperature of the process to 90-100°C. The greatest initiation effect is observed when ate-complexes of the MAlR4 type (M = Li, Na) are used: the reaction occurs with a higher rate already at 60-90°C affording R3Al free of admixtures of carbalumination products and dimers of α-olefins.
Insertion and isomerisation of internal olefins at alkylaluminium hydride: Catalysis with zirconocene dichloride
Weliange, Nandita M.,McGuinness, David S.,Gardiner, Michael G.,Patel, Jim
, p. 20098 - 20107 (2015)
The insertion of internal olefins (hydroalumination) and chain walking isomerisation at di-n-octylaluminium hydride [Al(Oct)2H], promoted by zirconocene dichloride [Cp2ZrCl2] has been studied. The reaction between [Cp2ZrCl2] and [Al(Oct)2H] in non-polar solvents leads to clusters containing bridging hydride ligands between Zr and Al. This system promotes hydroalumination of 1-octene but is largely ineffective for internal octenes (2-, 3-, 4-octene). In tetrahydrofuran the Zr-Al hydride clusters formed are more reactive and catalyse insertion and isomerisation of internal olefins to primary metal-alkyls, although this is accompanied by catalyst deactivation. Elimination and removal of 1-octene from the system post insertion/isomerisation was attempted, but it was found that the presence of the Zr catalyst leads to back-isomerisation to internal octenes, along with further decomposition with n-octane formation. Some possible pathways of catalyst decomposition, involving reduction of Zr and alkane elimination, have been studied theoretically.
General copper-catalyzed coupling of alkyl-, aryl-, and alkynylaluminum reagents with organohalides
Shrestha, Bijay,Thapa, Surendra,Gurung, Santosh K.,Pike, Ryan A. S.,Giri, Ramesh
, p. 787 - 802 (2016/02/18)
We report the first example of a very general Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. The reactions proceed for the couplings of alkyl-, aryl-, and alkynylaluminum reagents with aryl and heteroaryl halides and vinyl bromides, affording the cross-coupled products in good to excellent yields. Both primary and secondary alkylaluminum reagents can be utilized as organometallic coupling partners. These reactions are not complicated by β-hydride elimination, and as a result rearranged products are not observed with secondary alkylaluminum reagents even for couplings with heteroaryl halides under "ligand-free" conditions. Radical clock experiment with a radical probe and relative reactivity study of Ph3Al with two haloarenes, 1-bromonaphthalene and 4-chlorobenzonitrile, having two different redox potentials indicates that the reaction does not involve free aryl radicals and radical anions as intermediates. These results combined with the result of the Hammett plot obtained by reacting Ph3Al with iodoarenes containing p-H, p-Me, p-F, and p-CF3 substituents, which shows a linear curve (R2 = 0.99) with a ρ value of +1.06, suggest that the current transformation follows an oxidative addition-reductive elimination pathway.
