Visible‐Light‐Mediated C(sp³)–H Thiocarbonylation for Thiolactam Preparation with Potassium Sulfide

Abstract

Summary of main observation and conclusion We report herein a protocol for thiolactam preparation with potassium sulfide via visible‐light‐mediated C(sp3)–H thiocarbonylation, in which polysulfide dianions and radical anions generated from potassium sulfide were the key active species. A variety of thiolactams were straightforward established under mild conditions. Moreover, it was successfully applied to structural modification of tetrahydroberberine.

Applications of trisulfide radical anion S3˙− in organic synthesis

“…Subsequent homolysis of an S–S bond affords the thiolactam 121b (Scheme 40). 44 In a separate experiment it was shown that the iminium salt 122 can be converted to the 121b in the absence of the photocatalyst . Thus the role of the photosensitiser is the transformation of 120b into 122 .…”

“…Inspired by previous work on the in situ generation of S 3 ˙ − from K 2 S in DMF and consideration of the photometallic-catalyst-mediated C(sp 3 )–H thiocarbonylation of the N-heterocyclic skeleton 125 , 24,44 Zhou and co-workers designed a solvent-driven C(sp 3 )–H thiocarbonylation reaction utilizing K 2 S or elemental sulfur in solvents such as DMF and DMPU ( N , N ′-dimethylpropylenenurea). Various amine substrates such as tetrahydroisoquinoline, iso-indoline, and N , N -dimethyl-1-phenyl methanamine exhibited good reactivity to furnish the corresponding thioamides 126 in yields of 52–85% (Scheme 41).…”

Pd(II)-Catalyzed Direct γ-C(sp3)-H Arylation between Free β2-Amino Esters and β3-Amino Esters and Aryl Iodides Using a Catalytic Transient Directing Group

“…Recently, transient directing group (TDG)-catalyzed site-selective C–H functionalization has received significant attention due to the absence of additional directing groups installed and removed in situ. , Also, free primary amines used as substrates have realized Pd­(II)-catalyzed γ-C­(sp 2 )-H, γ-C­(sp 3 )-H, or δ-C­(sp 3 )-H arylation by employing TDGs . Dong et al used 8-formylquinoline as an exo-imine-type directing group to achieve arylation of free primary amines .…”

Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts

“…Anionic polysulfides are used in various research fields including alkali-metal–sulfur batteries, biological chemistry, material science, and organic synthesis. − Despite their well-explored photophysical properties, ,, their use as photocatalysts for chemical reactions has been reported only recently by Chiba and co-workers. , They showed that polysulfide anions possess a high reduction power after visible-light excitation, capable of single-electron reduction of aryl halides to generate synthetically valuable aryl radicals. The resulting aryl radicals were exploited in aryl–aryl cross-coupling, borylation, and hydrogenation reactions.…”