Three-Component Domino Reaction of Thioamide, Isonitriles, and Water: Selective Synthesis of 1,2,4-Thiadiazolidin-3-ones and (E)‑N‑(1,2-Diamino-2-thioxoethylidene)benzamides

The three-component domino reaction of thioamides, benzyl isocyanide, and water in the presence of a catalytic amount of both Pd(dppf)Cl₂ and Cu(OAc)₂ afforded novel 1,2,4-thiadiazolidin-3-one cyclic compounds, whereas the same reaction with tertiary alkylisonitriles in the presence of rare earth metal salt [La(OTf)₃] resulted in (E)-N-(1,2-diamino-2-thioxoethylidene)benzamide open-chain products. This divergent reaction enabled the one-pot construction of five (N–S, C–S, C–O, and two C–N) or four (C–S, C–N, C–O, and C–C) new chemical bonds. Mechanism studies indicate that the oxygen atom of the product was derived from H₂O.