Ni-Catalyzed Carboxylation of C(sp²)–S Bonds with CO₂: Evidence for the Multifaceted Role of Zn

Abstract

Nickel-catalyzed reductive carboxylation reactions of aryl electrophiles typically require the use of metallic reducing agents. At present, the prevailing perception is that these serve as both a source of electrons and as sources of Lewis acids that may aid CO2 insertion into the Ni-C bond. Herein, we provide evidence for the in situ formation of organometallic species from the metallic reductant, a step that has either been ruled out or has been unexplored in catalytic carboxylation reactions with metal powder reductants. Specifically, we demonstrate that Zn(0) acts as a reductant and that Zn(II) generates arylzinc species that might play a role in the C(sp 2)-S carboxylation of arylsulfonium salts. Overall, the reductive Ni-catalyzed C(sp 2)-S carboxylation reaction proceeds under mild conditions in a non-amide solvent, displays a wide substrate scope, and can be applied to a formal para C-H carboxylation of arenes.

Enantioselective CO2 Fixation Via a Heck‐Coupling/Carboxylation Cascade Catalyzed by Nickel

“…On the contrary, limitations of the method emerged from the accommodation of EWGs at the aromatic ring (i. e. 4-Cl, 4-CF 3 ) that led to the direct carboxylation of the benzene ring, prevalently. [14] The possibility to decorate the newly formed all carbon quaternary stereogenic centers with different substituents was then considered (Scheme 2c). In particular, aliphatic, aromatic and OMe groups were successfully installed at different distances from the stereocenter (2 k-o) resulting in similar and remarkable chemical and optical outcomes (ee up to 98 %).…”

Cu-Catalyzed Arylation of Bromo-Difluoro-Acetamides by Aryl Boronic Acids, Aryl Trialkoxysilanes and Dimethyl-Aryl-Sulfonium Salts: New Entries to Aromatic Amides

“…All used boronic acids 2 and some aryl trialkoxysilanes 3 are commercially available and were purchased from appropriate vendors. 2-Bromo-2,2-difluoroacetamides [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ], 1, 2-iodo-2,2-difluoroacetamides [ 54 ], aryl trialkoxysilanes 3 [ 58 , 59 , 60 , 61 , 62 , 63 , 64 ], sulfonium salts 4 [ 65 , 66 , 67 ], and calixarenes L1 , L2 [ 68 , 69 ] are known compounds in the literature and were prepared according to the known literature, and the spectral data are identical with the corresponding literature. Copies 1 H and 13 C-NMR spectra are placed in Supplementary Materials .…”

Catalytic Carbonylation and Carboxylation of Organosulfur Compounds via C−S Cleavage

“…Very recently,o ur group has accomplishedr eductive carboxylationo ft he CÀSb onds of arylsulfonium salts under an atmosphericp ressure of CO 2 . [23] By means of an ickel-neocuproinec omplex and Zn powder as ar educing reagent, arylsulfonium salts were converted to the corresponding benzoic acids with satisfying functional group compatibility (Scheme 20). For instance, furtherc onvertible phosphate and stannyl groups were well tolerated.…”

“…Because of the inertness and catalyst‐poisonous character of C−S bonds, such carbonylative transformations require harsh reaction conditions and/or fairly reactive substrates. Recently, sulfonium salts are emerging as satisfyingly general, sufficiently reactive, and readily accessible electrophilic coupling partners mainly by the contributions of Ritter, Procter, Zhang and us . As shown in Schemes –, several carbonylative transformations of high versatility have been also developed.…”