1: carbon disulfide With potassium hydroxide in tetrahydrofuran T=0°C; 0.75 h; 2: 1H-indene-1,3(2H)-dione in tetrahydrofuran T=0°C; 3: dimethyl sulfate in ethanol T=0°C; 5 h;

potassium fluoride in N,N-dimethyl-formamide addition; alkylation; 3 h;

in dimethyl sulfoxide