Rhodium‐Catalyzed Annelation of Benzoic Acids with α,β‐Unsaturated Ketones with Cleavage of C−H, CO−OH, and C−C Bonds

Abstract

In the presence of a[Cp*RhCl 2 ] 2 catalyst, the Lewis acid In(OTf) 3 ,a nd the mild base Na 2 CO 3 ,a romatic carboxylates and a,b-unsaturated ketones undergo au nique hydroarylation/Claisen/retro-Claisen process to give the corresponding indanones.I nt his carboxylate-directed ortho-CÀHa nnelation, the C À COR bond of the ketone and the CO À OH group of the aromatic carboxylate are cleaved, and the hydroxy group is transferred from the aromatic to the aliphatic acyl residue. This reactivity is synthetically useful, particularly when starting from cyclic ketones,w hich are converted into indanones bearing aliphatic carboxylate side chains,thus greatly increasing the molecular complexity of aromatic carboxylates in asingle step.Scheme 3. Preferential formation of diketones at incomplete conversion. Scheme 4. Mechanistic investigations. Angewandte Chemie Communications

Directing-Group-Controlled Ring-Opening Addition and Hydroarylation of Oxa/azabenzonorbornadienes with Arenes via C–H Activation

“…Finally, when a competitive reaction was performed between 4a and 4a- d 5 with 2a under the standard reaction conditions, a KIE value of 4.5 was observed (see Scheme c). These results indicate that the rate-determining step involves cleavage of the C–H bond. ,, Based on the control experiments and the literature reports, ,,,,,, we have speculated possible reaction pathways for the present addition reactions in the Supporting Information.…”

Rh-Catalyzed Annulation of Benzoic Acids, Formaldehyde, and Malonates via ortho-Hydroarylation to Indanones

“…The results implicate that the cleavage of the C–H bond might not be involved in the rate-determing step (Scheme , eq e). On the basis of previous reports , and our study, a plausible pathway for this three component reaction is depicted in Scheme . Initially, the ligand exchange of [Cp*RhCl 2 ] 2 with NaOAc leads to the formation of active catalyst Cp*Rh­(OAc) 2 I , which gives aryl-rhodium intermediate II through a carboxylate directed ortho -C–H activation.…”

“…A recent breakthrough has been developed involving the reaction of benzoic acids with α,β-unsaturated keones by Shi and Gooßen (Scheme ). , In Gooßen’s work, a carboxylate directed hydroarylation carried out by Rh/In catalysis, and a Claisen-type condensation, occurs directly from the free carboxylic acid rather than its corresponding ester (Scheme , eq b) . They further improved the yields of simple alkenyl methyl ketones by a bimetallic Ir/In system, and the substrate scope was successfully extended to 3-aryl alkenones (Scheme , eq c) .…”

Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

“…Gooßen explored the rhodium-catalyzed annulation of ortho- or meta -substituted benzoic acids with α,β-unsaturated ketones 473 to give indanone derivatives 474 ( Scheme 59 ) [ 146 ]. The process involved the insertion of the olefin into the Rh–C bond of 475 , previously fromed via concerted metalation-deprotonation from the free carboxylic acid 472 .…”