title: Electronic tuning of iron-oxo-mediated C-H activation: effect of electron-donating ligand on selectivity.
abstract: We have reported previously that an iron(III) complex supported by an anionic pentadentate monoamido ligand, dpaq(H) (dpaq(H) =2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamido), promotes selective CH hydroxylation with H2 O2 with high regioselectivity. Herein, we report on the preparation of Fe(III) -dpaq derivatives that have a series of substituent groups at the 5-position of a quinoline moiety in the parent ligand dpaq(H) (dpaq(R) , R: OMe, H, Cl, and NO2 ), and examine them with respect to their catalytic activity in CH hydroxylation with H2 O2 . As the substituent group becomes more electron-withdrawing, both the selectivity and the turnover number increase, but the selectivity of epoxidation shows the opposite trend.
authors.affiliation: Department of Molecular Chemistry and Biochemistry, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0321 (Japan), Fax: (+81) 774-65-6801. yhitomi@mail.doshisha.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hitomi
authors.forename: Kengo
authors.initials: K
authors.lastname: Arakawa
authors.forename: Masahito
authors.initials: M
authors.lastname: Kodera
keywords: CH activation; homogeneous catalysis; hydroxylation; iron; oxidation