Cyclopalladated Ferrocenylimine as Efficient Catalyst for the Syntheses of Arylboronate Esters

摘要

The cyclopalladated ferrocenylimine I and its phosphine adducts IIa-f were prepared and evaluated in the borylation of aryl halides. The tricyclo-hexylphosphine adduct IIb exhibited highly catalytic activity for the coupling of aryl and heteroaryl bromides containing various functional groups with low catalyst loading (2 mol%). Aryl and heteroaryl chlorides were smoothly converted into the corresponding boronates in the presence of the monophosphino-biaryl ligand (XPhos) adduct IIf. It was proposed that palladacycle was only a reservoir of the catalyti-cally active species from the investigation on the reaction mechanism.