Theoretical Investigations on the Rh(III)-Catalyzed Oxidative C-H Activation/Annulation of Salicylaldehydes with Masked Enynes: Mechanism Insights and Regioselectivity Origins

The mechanism underlying the rhodium(III)-catalyzed reaction of the C-H alkenylation/annulation reaction of salicylaldehydes with enynes has been thoroughly investigated using DFT calculations. Based on mechanistic studies, our focus primarily lies on the regioselectivity of asymmetric alkynes inserting into the Rh-C bond and the involvement of the auxiliary group OAc- in these reactions. Our theoretical study uncovers that, with acetate assistance, a stepwise SN2' cyclization, 1,3-Rh migration, β-H elimination, and reductive elimination process occur. Furthermore, we also explore the role of substitution at Cα (CH3 vs H) in the reaction. As demonstrated in this work, these findings are applicable to other related reactions.

Rh(III)-Catalyzed Oxidative C-H Activation/Annulation of Salicylaldehydes with Masked Enynes for the Synthesis of Chromones

A rhodium(III)-catalyzed oxidative C-H activation/annulation of salicylaldehydes with propargylic acetates has been developed for the regioselective synthesis of 3-vinyl chromones in good yields with broad functional group tolerance. 3-Vinyl chromones were converted into biologically active benzo[c]xanthone by I₂-mediated oxidative electrocyclization.

Highly-selective synthesis of functionalized spirobenzofuranones and diketones

A convenient and atom-economical rhodium(iii)-catalyzed highly-selective hydroacylation for the synthesis of spirobenzofuranones and diketones has been successfully developed.

Rhodium-Catalyzed Regioselective Formal Hydroacylation of Vinyl Epoxides toward Esters Involving β-Carbon Cleavage

Herein we disclose the first example of the formal hydroacylation reactions of vinyl epoxides with chelating aldehydes enabled by rhodium catalysis for the efficient construction of functionalized esters. Detailed investigations of the mechanistic pathway reveal that the presence of a 2-vinyl group is essential in contributing to the success of this regioselective reaction, which might proceed through β-carbon cleavage as the key procedure.