1: in tetrahydrofuran; diethyl ether T=0°C; 0.5 h; 2: With tetrakis(triphenylphosphine) palladium(0); copper(I) bromide in tetrahydrofuran; diethyl ether T=20°C; 3: With pyridine; pyridine hydrogenfluoride in tetrahydrofuran; diethyl ether; ethyl acetate T=20°C; 21 h;

acetic acid in tetrahydrofuran T=60°C; 72 h;

1: copper(l) iodide; tetrakis(triphenylphosphine) palladium(0); triethylamine / N,N-dimethyl-formamide / 16 h / 20 °C / Inert atmosphere 2: triethylamine / N,N-dimethyl-formamide / 1 h / -55 °C 3: N,N-dimethyl-formamide / -55 - 20 °C 4: pyridine; tetrabutyl ammonium fluoride; pyridine hydrogenfluoride / tetrahydrofuran / 16 h / 20 °C View Scheme

1: triethylamine; copper(l) iodide / tetrakis(triphenylphosphine) palladium(0) / N,N-dimethyl-formamide 2: tetrabutyl ammonium fluoride / tetrahydrofuran View Scheme

1: 5 percent Pd(CH3CN)2Cl2 / acetonitrile / 80 °C 2: OsO4, NMO, H2O / acetone; 2-methyl-propan-2-ol 3: TBAF 4: NaIO4, H2O View Scheme