Endo-Selective Iron Catalysts for Intramolecular Alkyne Hydrofunctionalization

Authors

Benjamin J. Bridge, The University of Western Ontario
Paul D. Boyle, The University of Western Ontario
Johanna M. Blacquiere, The University of Western OntarioFollow

Document Type

Article

Publication Date

1-1-2020

Journal

Organometallics

URL with Digital Object Identifier

10.1021/acs.organomet.0c00307

Abstract

Metal-ligand cooperative iron complexes of the type [Fe(Cp*)(PR2NPh2)(MeCN)]PF6 (R = Cy, Ph) were synthesized and characterized. Both derivatives were active toward the intramolecular hydroamination of 2-ethynylaniline and hydroalkoxylation of 2-ethynylbenzyl alcohol. In the latter case, only the six-membered endo heterocycle isochromene was observed, which suggests that the alkyne is activated by a vinylidene mechanism. The reaction of [Fe(Cp*)(PCy2NPh2)(MeCN)]PF6 with phenylacetylene indeed afforded a complex that was characterized as a vinylidene, which implicates an analogous intermediate in the hydrofunctionalization mechanism.