Syntheses of polyaluminium compounds by hydroalumination reactions, chelating Lewis acids possessing two and four coordinatively unsaturated aluminium atoms

Hydroalumination of CC triple bonds was achieved by treatment of the tetraalkynylbenzene derivative 1,2,4,5-(Me3SiCC)4C6H2 with di(tert-butyl)aluminium hydride. Depending on the stoichiometric ratio of the starting compounds multifunctional Lewis acids were obtained with two or four coordinatively unsaturated aluminium atoms. Alkenyl derivatives resulted which have the Al and H atoms in cis positions and the di(tert-butyl)aluminium and trimethylsilyl groups attached to the terminal carbon atoms of the CC double bonds.