title: Chelation-assisted Rh(I)-catalyzed ortho-alkylation of aromatic ketimines or ketones with olefins.
abstract: Described herein is the Rh(I)-catalyzed ortho-alkylation of aromatic ketimines or ketones with olefins. This method showed high reactivity and selectivity to monoalkylation for a variety of olefins including 1-alkenes with an allylic proton, alpha,omega-dienes, and internal olefins. For a mechanistic study, H/D exchange experiments were carried out, which demonstrated that the ortho C-H bond could be easily cleaved even at the low temperature of 45 degrees C. The key step of this reaction is the formation of a stable five-membered metallacycle by a chelation-assisted ortho C-H bond activation. Furthermore, the direct ortho-alkylation of aromatic ketones with the Rh(I) complex was successfully achieved by adding 50 mol % of benzylamine as a chelation-assistant tool.
authors.affiliation: Department of Chemistry, Yonsei University, Seoul, South Korea. junch@yonsei.ac.kr
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Jun
authors.forename: Choong Woon
authors.initials: CW
authors.lastname: Moon
authors.forename: Jun-Bae
authors.initials: JB
authors.lastname: Hong
authors.forename: Sung-Gon
authors.initials: SG
authors.lastname: Lim
authors.forename: Kwan-Yong
authors.initials: KY
authors.lastname: Chung
authors.forename: Yeon-Hee
authors.initials: YH
authors.lastname: Kim