Construction of Benzothiophene-Fused 1,2,4-Triazocines via a Skeletal Editing Strategy and DFT Study on the Reaction Mechanism

A series of benzothiophene-fused 1,2,4-triazocines were successfully synthesized through a one-pot skeletal editing strategy. The synthesis commenced with a [4 + 3] cycloaddition reaction to afford a benzothiophene-fused 1,2,4-triazepane intermediate. Subsequently, the target benzothiophene-fused 1,2,4-triazocane was obtained via a single-atom skeletal editing strategy, employing trimethylsulfoxonium iodide as a one-carbon reagent. Density functional theory (DFT) calculations revealed that the skeletal editing process proceeded through a tandem ring-opening/ring-closure sequence.