Jun-Bae Hong

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

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.

HYDROACYLATION OF 1-ALKENE WITH HETEROAROMATIC ALDEHYDE BY RH(I) AND ADDITIVES

Abstract Hydroacylation of 1-alkene with a heteroaromatic aldehyde such as pyridinecarboxaldehyde, thiophenecarboxaldehyde and furfural derivatives under cocatalyst of Wilkinsons complex and 2-amino-3-picoline gave poor yield of hydroacylated product. The addition of a catalytic amount of bis-(cyclopentadienyl)zirconium dichloride or bis(cyclopentadienyl)titanium dichloride as an additive dramatically increased the yield of the hydroacylated ketone product.