Primary alanes and alanates: useful synthetic reagents in aluminum chemistry

Abstract

Primary alanes [RAlH 2] 2 can be stabilized kinetically by employment of very bulky alkyl or aryl substituents. They are easily prepared by reacting the appropriate lithium trihydroalanate precursor with organic halides, anhydrous hydrogen halides or halogens. Reactions of these aluminum hydrides with a wide variety of substrates ranging from protic reagents such as water, alcohols, amines, phosphines or thiols over ketones, nitriles or isonitriles to silylated species such as siloxanes or silyl halides are presented. Primary alanes were shown to be unique starting materials for a number of interesting compounds that were otherwise not accessible, or only available in low yields. In addition, postulated intermediates of aluminum hydride reductions of organic substrates such as ketones or nitriles can be isolated when using bulky primary alanes.