Expedient Synthesis of 1,5-Diketones by Rhodium-Catalyzed Hydroacylation Enabled by C–C Bond Cleavage

Abstract

A rhodium-catalyzed intermolecular hydroacylation reaction of vinyl cyclobutanols with non-chelating aldehydes has been developed. This reaction offers a new and atom-economical approach for the selective preparation of 1,5-diketones in high yields. Experimental data suggest a sequential ring-opening, transfer hydrogenation, and hydroacylation mechanism. We propose that aldehyde decarbonylation is avoided by the formation of a novel rhodium enolate species that also accounts for the compatibility of a broad range of aldehydes and its anti-Markovnikov selectivity.

Cleavage of Carbon–Carbon σ-Bonds of Four-Membered Rings

“…37 1-Vinylcyclobutanol 77 couples with benzaldehyde 78 through ring-opening to produce acyclic 1,5-diketone 79 (Scheme 20). 38 Initially, the four-membered ring opens to generate alkylrhodium intermediate 80, which rearranges to rhodium enolate 82 through β-hydrogen elimination and subsequent 1,4-addition of the resulting rhodium hydride species. Now that the rhodium center is located close enough to the alkene moiety, it promotes a hydroacylation reaction of the carbon−carbon double bond with benzaldehyde 78.…”

Recent Advances in Intermolecular Hydroacylation of Alkenes with Aldehydes through Rhodium Catalysis

“…As a result of the release of ring strain, β-carbon elimination might occur before hydroacylation across the extended carbon chain to give 1,5-diketones. 23…”

Density Functional Computations for Co(I)‐Catalyzed Intermolecular Hydroacylation of Benzaldehydes

“…Hydroacylation, the catalytic addition of a formyl C−H bond across an alkene, alkyne, aldehyde, or ketone, represents an ordinary, atom‐efficient, viable, green method to carbonyl compounds. Many transition metals such as cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium, and gold have been reported to catalyze intramolecular or intermolecular hydroacylation.…”