Hydroalumination of silicon centered dialkynes - Synthesis of mixed alkenyl-alkinylsilanes [Hydroaluminierung von Silicium-zentrierten dialkinen - Synthese gemischtsubstituierter alkenyl-alkinylsilane]

摘要

Bis(phenylethynyl)silanes reacted with equimolar quantities of various dialkylaluminium hydrides, R_2Al-H [R = CH_2tBu, tBu, tBu, CH(SiMe_3)_2], by hydroalumination and addition of a Al-H bond to a C≡C triple bond. Alkenyl-alkynylsilanes were formed, which had the aluminium atoms in geminal positions with the silicon atoms and adopt a cis arrangement of aluminium and hydrogen at the resulting C=C double bonds in most cases cis/trans-Rearrangement with the forma-tion the trans-addition products was observed only for the two sterically least shielded compounds. Intramolecular interactions of the coordinatively unsaturated aluminium, atoms with the a-carbon atoms of the intact alkynyl groups were detected by crystal structure determinations for the tert-butyl and neopentyl derivatives, whereas they did not occur with bulky bis(trimethylsilyl)methyl substituents.