Transition-metal-catalyzed remote C–H functionalization of thioethers

Abstract

This minireview systematically introduces the major advances and their mechanisms in the field of transition-metal-catalyzed remote C–H functionalization of thioethers.

Pd(II)‐Catalyzed β‐C(sp3)−H Functionalization of Ugi 4‐CR Adducts Using the 2‐(Methylthio)‐aniline (MTA) Directing Group

“…A plausible mechanism that operates through a Pd(II)/Pd(IV) catalytic cycle can be rationalized in scheme 6 [34] . Initially, Pd(OAc) 2 is coordinated to the bidentate MTA directing group in adduct 9 a leading the Pd(II) intermediate A .…”

“…[33] A plausible mechanism that operates through a Pd(II)/Pd(IV) catalytic cycle can be rationalized in scheme 6. [34] Initially, Pd(OAc) 2 is coordinated to the bidentate MTA directing group in adduct 9 a leading the Pd(II) intermediate A. Posteriorly, the β-C(sp 3 )À H bond activation is promoted through a concerted metalation-deprotonation mechanism (CDM) [35] to access organometallic species B accompanied with a release of AcOH. The species B undergoes oxidative addition by aryl iodide 10, leading to high oxidation state palladium(IV) species C, [36] which presents a concomitant reductive elimination process promoted by AgOAc to access arylated compound 11 a, and recovering the active Pd(II) catalyst.…”

Metal‐Free and NBS‐Mediated C(sp3)−S Bond Cleavage of Thioethers to Access Alkyl Bromides

“…Thioethers are not only widely present in natural products, pharmaceuticals and functional materials but also serve as significant precursors in organic synthetic chemistry. [1][2][3][4] Recently, the diverse transformations of thioethers have garnered significant attention in these fields. [2][3][4] Among these fields, thioethers exhibit immense potential for selective CÀ S bond cleavage to construct various kinds of organic compounds.…”

“…[1][2][3][4] Recently, the diverse transformations of thioethers have garnered significant attention in these fields. [2][3][4] Among these fields, thioethers exhibit immense potential for selective CÀ S bond cleavage to construct various kinds of organic compounds. [2,3] Previous studies on CÀ S bond cleavage predominantly relied on the insertion of various transition-metal catalysts into the C(sp 2 )À S bonds, leading to the selective cleavage of C(sp 2 )À S bonds (Scheme 1a).…”

Thioether-Assisted Cu-Catalyzed C5–H Arylation of Imidazo[1,5-a]pyridines

“…The other thioether groups tested led to inferior results (Scheme a). It should be noted that although both thioethers as directing groups and Cu-catalyzed C–H activation reactions , have been extensively studied, thioether-directed Cu-catalyzed C–H functionalization is barely known. The ligand played an important role, as a lower yield of 36% was obtained in the absence of any ligand.…”