1: C5H8O2(2-)*2Li(1+) With N,N'-dimethyl-N,N'-propyleneurea in tetrahydrofuran T=5°C; 0.5 h; 2: ethyl iodide in tetrahydrofuran T=20°C; 2 h;

1: C5H8O2(2-)*2Li(1+) With N,N'-dimethyl-N,N'-propyleneurea in tetrahydrofuran T=5°C; 0.5 h; 2: methyl iodide in tetrahydrofuran T=20°C; 2 h;

1: C5H8O2(2-)*2Li(1+) With N,N'-dimethyl-N,N'-propyleneurea in tetrahydrofuran T=5°C; 0.5 h; 2: 2-iodo-propane in tetrahydrofuran T=20°C; 2 h;

1: C5H8O2(2-)*2Li(1+) With N,N,N',N',N'',N''-hexamethylphosphoric triamide in tetrahydrofuran; hexane T=20°C; 0.5 h; 2: 1-iodo-propane in tetrahydrofuran; hexane T=0 - 20°C; 1 h; 3: With hydrogenchloride; water in tetrahydrofuran; hexane T=0°C; pH=1 - 2;