Iron-Catalyzed Transfer Hydroalumination of Alkynes

Abstract

The limited availability of efficient synthetic methods for organoaluminum compounds constrains their broader applications. The transfer hydroalumination of alkynes emerges as a promising strategy for synthesizing alkenylaluminum species; however, achieving precise control of the selectivity remains a formidable challenge. Herein, we disclose a highly chemo-, regio-, and stereoselective transfer hydroalumination of alkynes, catalyzed by well-defined iron complexes, utilizing commercially available AlEt₃ as the hydroalumination reagent. The regioselectivity of the transfer hydroalumination reaction involving terminal alkynes can be effectively modulated by changing the 2,9-aryl substituents on the ligands with the observation of cis-α-selectivity not previously documented in the literature. Furthermore, we demonstrate unprecedented cis-β-selective transfer hydroalumination of simple unsymmetrical internal alkynes. This work not only broadens the scope of transfer hydroalumination reactions but also enhances the synthetic methodologies and diversity of organoaluminum compounds, highlighting the significant potential of iron catalysts in the development of organometallic reagents.