Iron-Catalyzed Regiodivergent Alkyne Hydrosilylation

Although
tremendous effort has been devoted to the development
of methods for iron catalysis, few of the catalysts reported to date
exhibit clear superiority to other metal catalysts, and the mechanisms
of most iron catalysis remain unclear. Herein, we report that iron
complexes bearing 2,9-diaryl-1,10-phenanthroline ligands exhibit not
only unprecedented catalytic activity but also unusual ligand-controlled
divergent regioselectivity in hydrosilylation reactions of various
alkynes. The hydrosilylation protocol described herein provides a
highly efficient method for preparing useful di- and trisubstituted
olefins on a relatively large scale under mild conditions, and its
use markedly improved the synthetic efficiency of a number of bioactive
compounds. Mechanistic studies based on control experiments and density
functional theory calculations were performed to understand the catalytic
pathway and the observed regioselectivity.