Herein described is the chelation-assisted C-C bond activation of unstrained ketones under the co-catalyst system of Rh(PPh3)3Cl and 2-amino-3-picoline (1). This reaction is based on the strategy we recently developed in hydroacylation with aldehydes in which 2-aminopyridine derivatives function as chelation-assistant tools. Unstrained ketones having a β-hydrogen gave rise to alkyl-exchanged ketones via this C-C bond activation under an excess of external olefins. In the absence of external olefins, cycloheptanone underwent a ring contraction to generate five- and six-membered cyclic ketones. Instead of unstrained ketones, sec-alcohols were also employed as a substrate for this C-C bond activation via hydrogen transfer. The reaction of allylamine derivatives under [Rh(C8H14)2Cl]2 and PCy3 afforded symmetric dialkyl ketones via a series of reaction such as olefin isomerization, C-H bond activation, and C-C bond activation. The key intermediate, the imine derived from 1 was generated from a primary amine through dehydrogenation followed by transimination. Consequently, the Rh(I)-catalyzed C-C bond activation of unstrained ketones and their equivalents was demonstrated by utilizing a chelation-assistance strategy.
Bibliographical noteFunding Information:
These works were supported by the National Research Laboratory program (Organotransition Metal Catalysis Lab. 2000-N-NL-01-C-271), administrated by the Ministry of Science and Technology. We also acknowledge the Brain Korea 21 program.
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology
- Physical and Theoretical Chemistry