hydrogen sulfide; triethylamine in ethanol T=5°C; ice bath, overnight;

1: 6.5 percent / NaOH / aq. ethanol / 20 h / Ambient temperature 2: 90 percent / hydrogen sulfide, triethylamine / ethanol / 5 °C / ice bath, overnight View Scheme

in methanol T=66°C; 2 h; pH=9;