Chelation-Assisted RhI-Catalyzed ortho-Alkylation of Aromatic Ketimines or Ketones with Olefins

✍ Scribed by Chul-Ho Jun; Choong Woon Moon; Jun-Bae Hong; Sung-Gon Lim; Kwan-Yong Chung; Yeon-Hee Kim

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 161 KB
• Volume: 8
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/1521-3765(20020118)8:2<485::aid-chem485>3.0.co;2-1

✦ Synopsis

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, a,w-dienes, and internal olefins. For a mechanistic study, H/D exchange experiments were carried out, which demonstrated that the ortho C À H bond could be easily cleaved even at the low temperature of 45 8C. The key step of this reaction is the formation of a stable five-membered metallacycle by a chelation-assisted ortho CÀH 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.