Palladium-Catalyzed Regiodivergent Decarboxylative Hydrothiocarbonylation of Vinylarenes Using Oxalic Acid Monothioesters

Abstract

Oxalic acid monothioester (OAM), an easily accessible and bench-stable reagent, is reported herein as a synthetic equivalent of thioester for palladium-catalyzed decarboxylative hydrothiocarbonylation of vinylarenes to achieve both branched and linear regioselectivity. The reactions provided user-friendly synthetic methods for preparation of alfa- or beta-arylated propionic acid thioesters from vinylarenes without directly handling toxic carbon monoxide and odorous thiols.

Visible Light-Accelerated Palladium-Catalyzed Thiocarbonylation Using Oxalic Acid Monothioester with Aryl/Alkenyl Sulfonium Salts

“…In 2019, Shang’s group used OAMs as feedstock and reported palladium-catalyzed thiocarbonylation of organohalogenates and hydrogen thiocarbonylation of unsaturated hydrocarbons (Figure a,b) . In 2022, Shang’s group reported palladium-catalyzed regiodivergent decarboxylative hydrothiocarbonylation of vinylarenes using OAMs (Figure c) . We report here the palladium-catalyzed decarboxylative thiocarbonylation reaction of aryl and alkenyl sulfonium salts under mild light conditions using OAMs as the thiocarbonylation reagent, which was achieved by visible light-accelerated palladium catalysis (Figure d) .…”

Pd-Catalyzed Regioselective Hydrocarboxylation of Alkyl Terminal Olefins with Oxalic Acid

“… For example, Alper and co-workers earlier showed that the corresponding acids were obtained from 1-heptene in 65% yield and 70:30 l/b ratio with Pd/C-dppb, oxalic acid, and CO (40 atm) in DME at 150 °C . However, the hydrocarboxylation of olefins with oxalic acid in the absence of CO gas has been rarely explored. , Very recently, we found that oxalic acid can serve as an effective CO surrogate for the hydrocarboxylation of olefins in the presence of Ac 2 O, and a variety of vinyl arenes can be efficiently hydrocarboxylated, providing either 2-arylpropanoic or 3-arylpropanoic acids in good to high regioselectivities under mild conditions (Scheme ). However, when an alkyl terminal olefin such as 1-octene was subjected to the reaction conditions, low yields or low regioselectivities were obtained [55% yield and 2:1 l/b ratio with Pd­(OAc) 2 / L1 or 28% yield and 5:1 b/l ratio with (NH 4 ) 2 PdCl 4 / L2 ] .…”

Pd-Catalyzed Regiodivergent Hydrocarboxylation of Olefins with Oxalic Acid: A Remarkable Effect of the Counteranion on Regioselectivity

“…The counteranion of the Pd salt has displayed a profound impact on the regioselectivity. While there are a number of reports on hydrocarboxylation of olefins with oxalic acid along with CO, there are few examples of such process with oxalic acid in the absence of additional CO. − Herein, we report our preliminary results on this subject.…”