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Z. Naturforsch. 2013,
68b, 503 – 517
doi:10.5560/ZNB.2013-3070
Hydroalumination versus Deprotonation of Alkynes with Sterically Demanding Substituents
Institut für Anorganische und Analytische Chemie der Universität Münster, Corrensstraße 30, 48149 Münster, Germany
Reprint requests to Prof. Werner Uhl. E-mail:
uhlw@uni-muenster.de
Received February 27, 2013 / published online Juli 2, 2013
Dedicated to Professor Heinrich Nöth on the occasion of his 85th birthday
Treatment of sterically highly shielded terminal alkynes, H–C≡C-aryl, with dialkylaluminium and dialkylgallium hydrides, R2E–H, afforded by hydrogen release dimeric dialkylelement alkynides with a four-membered E2C2 heterocycle independent of the bulk of the aryl groups. A rare example of a monomeric alkynylaluminium compound was only obtained with very bulky CH(SiMe3)2 groups attached to the metal atoms and by salt elimination reaction. The steric shielding by the bulky aryl groups did not prevent condensation reactions. Hydroalumination of 1-(trimethylsilyl)-2-(2,6-dimethylphenyl)ethyne using Me2Al–H resulted in a divinyl compound by elimination of trimethylaluminium.
Key words: Aluminium, Gallium, Hydroalumination, Hydrogallation, Alkynes