Nickel-Catalyzed Reductive Aryl Thiocarbonylation of Alkene via Thioester Group Transfer Strategy

Abstract

Herein reported is a nickel-catalyzed reductive aryl thiocarbonylation of alkene via thioester group transfer strategy by using simple and readily available thioesters. In contrast to traditional activation of weaker C­(acyl)–S bond, the C­(acyl)–C bond of thioester was selectively cleaved to enable this reaction under mild conditions. Furthermore, this approach features operational simplicity and broad substrate scope, providing a complementary and practical route for thioester synthesis without requiring toxic thiol or CO gas.

Nickel-catalyzed carbonylation of thioacetates with aryl iodides via CO insertion and C–S bond cleavage

“…These results indicated that insertion of Ni(I) into the S-S bond is easier and that the insertion of CO occurred after C-S or S-S bond cleavage. Based on the above the experimental data and previous work, 17 a plausible reaction mechanism is proposed in…”

“…Based on the above the experimental data and previous work, 17 a plausible reaction mechanism is proposed in Scheme 2. First, an Ni(0) species is formed by reduction with Zn powder, then, the species inserts into the Ph-I bond of the iodobenzene to form the intermediate A.…”

“…More recently, new progress was reported in this field, in which some novel protocols were developed for the synthesis of thioesters. [16][17][18][19] Herein, we report a novel process for the synthesis of aryl thioesters via nickelcatalyzed carbonylation of thioacetates or dialkyl disulfides with aryl iodides under mild conditions.…”

Palladium-Catalyzed Thiocarbonylations with Triisopropylsilyl Thioethers

“…Purification by flash silica gel column chromatography (hexane/ethyl acetate = 10/1) afforded 2g (21.5 mg, 83%) as a colorless oil: Rf = 0.15 (hexane/ethyl acetate = 4/1). [3]…”

“…For example, the oxidative addition of compound I (Scheme 1a) to palladium affords a σ-aryl palladium intermediate, which is followed by alkene insertion to afford σ-alkyl palladium intermediate II because β-elimination does not occur owing to the formation of the adjacent all-carbon quaternary center; subsequent reaction with a nucleophile affords compound III. 1 Indeed, reactions of σ-alkyl palladium intermediate II with bis(pinacolate) diboron, 2 hexamethyldisilane, hexamethyldistannane, 3 and diethyl H-phosphonate 4 have been reported to afford the corresponding alkyl pinacol borane, silane, stannane, and phosphonate, respectively. Recently, we reported a palladium-catalyzed carbothiolation reaction affording IV using an alkyl and aryl TIPS thioethers, which proceeds via σ-alkyl palladium intermediate II generated from compound I (Scheme 1b).…”