ethane-1,2-dithiol; trifluoroacetic acid in N,N-dimethyl-formamide T=0°C; 0.25 h;

1: HCl, isoamyl nitrite / dimethylformamide; dioxane / 0.17 h / -30 °C 2: Et3N / dimethylformamide / -20 °C / pH 8 3: 68 percent / TFA, 1,2-ethanedithiol / dimethylformamide / 0.25 h / 0 °C View Scheme

Multistep reaction;