A robust transition-metal-free strategy is presented to access novel β-carboline-tethered benzothiophenone derivatives from 1(3)-formyl-β-carbolines using elemental sulfur activated by Et3N/DMSO. This expeditious catalyst-free reaction proceeds through the formation of β-carboline-based 2-nitrochalcones followed by an incorporation of sulfur to generate multifunctional β-carboline-linked benzothiophenones in good to excellent yields. The synthetic strategy could also be extended towards the synthesis of β-carboline-linked benzothiophenes. Moreover, the afforded products emerged as promising fluorophores and displayed excellent light-emitting properties with quantum yields (ΦF) up to 47%.
Facile synthesis of 1,2-benzisothiazoles from amidines and elemental sulfur via N–S/C–S bond formation under transition-metal-free conditions has been developed with good tolerance of a broad range of functional groups.
A transition-metal-free sulfite-promoted three-component C–H sulfuration between imidazoheterocycles, elemental sulfur, and bromofluoroacetate is developed. Sulfites, including Na2S2O4, NaHSO3, and Na2S2O3, are able to promote the formation of two C–S bonds in one step using elemental sulfur as a green sulfurating agent, allowing the rapid introduction of the synthetically useful S-fluoroacetate group into imidazoheterocycles. These new imidazoheterocycle derivatives bearing an S-fluoroacetate group can be easily modified to produce pharmaceutically attractive compounds.
A multi-component reaction of arylamines, elemental sulfur and CO2 (1 atm) is reported to generate valuable thiazolidin-2-ones and 1,3-thiazinan-2-ones in moderate to good yields under transition-metal-free reaction conditions.
Et3N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties
