Vanadyl species-catalyzed complementary β-oxidative carbonylation of styrene derivatives with aldehydes

Abstract

A series of oxometallic species and metal acetylacetonates (acac) was examined as catalysts for oxidative carbonylation of styrene with benzaldehyde using t-butylhydroperoxide as the co-oxidant in warm acetonitrile. Among them, VO((acac)2 and vanadyl(IV) chloride were found to be the only catalyst class to achieve cross-coupling processes by judiciously tuning the ligand electronic attributes, leading to β-hydroxylation- and β-peroxidation-carbonylation of styrene, respectively, in a complementary manner. Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene.

Three‐Component Acylation/Peroxidation of Alkenes through Visible‐Light Photocatalysis

“…The acyl radical initiated di‐functionalization of alkenes were also reported. Li, Chen, and their co‐workers individually demonstrated the radical carbonylation‐peroxidation of alkenes, FeCl 2 and VOCl 2 were used as the catalysts, respectively [5a,b] . n Bu 4 NBr also could be used as the catalyst for carbonylation‐peroxidation reactions [7] …”

Radical-Mediated Difunctionalization of Styrenes

“…27 In 2015, Weng, Chen, and co-workers reported the same difunctionalization of styrenes catalyzed by a vanadium salt, V(O)(acac) 2 , However, only V(O)(acac) 2 can catalyze this reaction, other metallic acetylacetonato (acac) salts did not work under similar conditions ( Table 1, entry 24). 28 In 2019, the Bao group developed an acylazidation of styrenes with aldehydes using an iron salt as the catalyst and TBHP as the oxidant. In this transformation, aldehydes were applied as the acyl radical source and TMSN 3 was used as the azido source ( Table 1, entry 25).…”

Recent Advances in Radical Difunctionalization of Simple Alkenes

“…Different from the above‐mentioned formation of α‐carbonyl epoxides, Chen and coworkers described tandem and complementary β‐hydroxylation/carbonylation and β‐peroxidation/carbonylation of styrenes by adjusting the ligand environment of a vanadyl center [Scheme , (d)] . VO(acac) 2 and vanadyl(IV) chloride were the only catalysts to achieve this coupling.…”