1: 2-methylmercapto-5-mercapto-1,3,4-thiadiazole With sodium hydride in N,N-dimethyl-formamide; benzene T=0°C; 0.25 h; 2: 3-chloro-2-pyrazinecarbonitrile in N,N-dimethyl-formamide; benzene T=80°C; 4 h;