Trithiocarbonate Anion as a Sulfur Source for the Synthesis of 2,5-Disubstituted Thiophenes and 2-Substituted Benzo[b]thiophenes

Abstract

The trithiocarbonate anion (CS 3 2− ) was generated in situ from CS 2 and KOH in dimethyl sulfoxide by a simple method and used as a novel synthetic equivalent of the S 2− synthon for the synthesis of 2,5-disubstituted thiophenes from 1,3butadiynes. Additionally, this system was employed for the metal-free synthesis of 2-substituted benzo[b]thiophenes from 2haloalkynyl (hetero)arenes. These compounds were obtained from a cheap and readily available sulfur source in moderate to good yields, with good functional group tolerance.

Photocatalytic Activation of Elemental Sulfur Enables a Chemoselective Three-Component Thioesterification

“…Subsequently, we conducted experiments where a 1,3-diyne was added to the thioesterification in order to obtain evidence of the fragmentation of S 8 during photocatalysis. Previous reports have shown that anionic sulfur species such as hydrosulfides, S 3 radical anions, and trithiocarbonate anions can couple with 1,4-diphenyl-1,3-butadiyne 25 to provide a 1,4-diphenylthiophene 26 . , We obtained thiophene 28 in 91% yield following the reaction of 1,3-diyne 25 under the optimal conditions in conjunction with the complete cessation of the thioesterification reaction and full recovery of α-ketoacid 2 (Scheme B, eq 4). Moreover, we found that the use of diphenyltetrasulfide 27 ( E 1/2 = −0.53 V vs SCE) instead of S 8 also afforded thioester 3 and a similar inhibition of the thioesterification as seen in eq 4 was observed (eq 5).…”

Red-Light-Induced N,N′-Dipropyl-1,13-dimethoxyquinacridinium-Catalyzed [3+2] Cycloaddition of Cyclopropylamines with Alkenes or Alkynes

“…The water bath needs to be refilled with room temperature deionized water every 12−18 h. With the above setup, the reaction temperature can be maintained at 21−23 °C within the water bath during the reaction for us. Substrates 1a-1b, [2] 1d-1f, [2] and 4a-4c [3] are known compounds in the literature. Products 3a, 3b [2] , 3e-3i [4] , and 3l are known compounds in the literature.…”

“…Following the reported procedure: . [3] In a N2 glove box, the substrate terminal alkyne S3 (1.0 eq. ), CuI (1.0 eq.…”

“…Cyclopentyl functional group motifs are prevalent in a wide range of bioactive pharmaceuticals and natural products such as peramivir, 1 aristeromycin, 2 Prostaglandin F2α, 3 and Vibralactone 4 (Figure 1). As a consequence, various strategies to their synthesis have been developed.…”

Evidence of a Photoinduced Electron-Transfer Mechanism in the Fluorescence Self-quenching of 2,5-Substituted Selenophenes Prepared through In Situ Reduction of Elemental Selenium in Superbasic Media

“…In this sense and aiming our continuous interest in the synthesis of chalcogen compounds, − the present study describes a novel methodology involving in situ reduction of elemental selenium to generate a nucleophilic Se 2– species in superbasic media [KOH and dimethylsulfoxide (DMSO)] to produce 2,5-disubstituted photoactive selenophenes. The scope of the methodology was investigated using 1,3-diyne derivatives containing different substituents with electron-donating and electron-withdrawing features in different positions to verify electronic and steric effects.…”