Because unsaturated alanes are oxygen- and moisture-sensitive, they are most often prepared for immediate use without isolation. However, the method of preparation determines the configuration of the intermediate unsaturated alane, which is directly related to the configuration of the product (transfer of the alkenyl group occurs with retention of configuration). Thus, an understanding of available hydroalumination methods is important for the study of reactions of unsaturated alanes. This second describes the most common methods of hydroalumination, and subsequent chemical reactions that the resulting alkenylalanes may undergo.