Synthesis of Nitriles and Symmetrical Organic Sulphides from Biprotic Carbothioamides and an α-Halogenated Ketone, Ester or Nitrile

Abstract

Thioacetamide has been used as an elegant sulphur transfer reagent for C-S-C coupling of reactive halides.^1–4 Sulphur extrusion of biprotic carbothioamides to form corresponding nitriles has been reported with the help of (i) dichlorocarbene;⁵ (ii) triphenylphosphine, carbon tetrachloride, triethylamine;⁶ (iii) diethyl azocarboxylate, triphenylphosphine;⁷ and (iv) soft metal ions.⁸ Here, we report that under non-hydrolytic conditions viz. DMF/OEt, EtOH/OEt and DMF/Et₃N, biprotic carbothioamides (1, R=CH₃, C₆H₅, CH₂C₆H₅) react with bromoacetophenone (2, Z=COC₆H₅), ethyl bromoacetate (2, Z=COOEt).