Preparation of NCN Pincer Palladium Complexes via a Ligand Introduction Route

Significance

A variety of NCN pincer palladium complexes (1a-g and 2a-d) were readily prepared from trans-(4-tert-butyl-2,6-diformyl-phenyl)chlorobis(triphenylphosphine)palladium (3) via dehydrative introduction of the corresponding alkylimino and pyrroloimidazolone ligand groups (ligand introduction route) in high yields (66-98%). The catalytic properties of the imino and the pyrrolo­imidazolone pincer palladium complexes were examined for the Heck reaction (eq. 1) and the asymmetric Michael reaction (eq. 2) to demonstrate their high catalytic activity and high enan­tioselectivity.