1H-imidazole; 1,3-dimethyl-imidazolidin-2-one; iodine; triphenylphosphine in diethyl ether 0.5 h;

sodium iodide in acetone 5 h; Reflux;

(i) nBuLi, (ii) PBr3, (iii) NaI; Multistep reaction;

1: 1.) lithium bistrimethylsilylamide / 1.) HMPTA, THF, from -75 to -70 deg C, 1.5 h, 2.) HMPTA, THF, from -75 to -70 deg C, 1 h 2: 95 percent / diisobutylaluminium hydride / hexane / 1 h / -75 °C 3: 100 percent / Amberlite IRA-400 / methanol / 24 h / Ambient temperature 4: 97 percent / H2 / Lindlar's catalyst / hexane View Scheme

1,3-dimethyl-imidazolidin-2-one; copper(l) chloride T=80°C; 2 h;

Yield given. Multistep reaction;

1: Cu(I) 2: 90 percent / tetrahydrofuran / 12 h / 65 °C 3: 91 percent / LiAlH4 / diethyl ether / 5 h / 25 °C 4: 76 percent / dimethyl(S,S)(-)-tartarate 5: 90 percent / H2 / Lindlar / tetrahydrofuran / 760 Torr 6: 84 percent / O2 / oxidation with Collins reagent 7: 94 percent / tetrahydrofuran / -78 deg C, 10 min,; and then from -78 deg Cto 0 deg C over 1 h. 8: 84 percent / acetic acid; acetonitrile; H2O / 6 h / 25 °C 9: triphenylphosphine, imidazole, I2, diisopropylamine / diethyl ether; acetonitrile / 0.67 h / 25 °C 10: acetonitrile / 16 h / 60 °C 12: 1.) potassium isopropoxide; 2.) base / 1.) 0 deg C, 1 h; 2.) hydrolysis View Scheme

1: methyl malonic acid diethylester With lithium diisopropyl amide in tetrahydrofuran; hexane T=-78°C; 1 h; 2: 1-iodopent-2-yne in tetrahydrofuran; hexane T=-78°C; 1 h;