1: 2,5-dibromothiophene With n-butyllithium in tetrahydrofuran; hexane T=-78 - 0°C; 0.5 h; Inert atmosphere; 2: N,N-dimethyl-formamide in tetrahydrofuran; hexane T=20°C; 2 h; Inert atmosphere; 3: With tert.-butyl lithium in tetrahydrofuran; hexane; pentane T=-78 - 20°C; Inert atmosphere;

aluminium in N,N-dimethyl-formamide byproducts: Al(3+); Electrolysis; electrolysis carried out in a single-compartment cell at room temp., starting materials dissolved in DMF containing KBr or n-Bu4NBr, solvent andexcess B(OCH3)3 evaporated under vacuum, medium hydrolysed at 0° C with an HCl or H2SO4 soln.; extraction with Et2O (3 x 20 ml if the solvent evaporated or 3 x 60 ml otherwise), dried over sodium or magnesium sulfate and concentrated undervacuum, side product phenol formation avoided by work-up under inert at mosphere, recrystallized in CH2Cl2;

1: 90 percent / 600 °C / 0.01 Torr / flash vacuum pyrolysis 2: CH2Cl2 / Ambient temperature View Scheme

in dichloromethane Ambient temperature; Yield given. Yields of byproduct given;

Yield given. Multistep reaction;

C20H25N2(1+)*Cl(1-); water; oxygen; 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile T=20°C; 4 h; Schlenk technique;

sodium cyanide in N,N-dimethyl-formamide Stetter reaction;

1: methanol / 1 h 2: air View Scheme

1: ethanol / 2 h / Inert atmosphere; Reflux 2: air / chloroform / 5 h / 20 °C View Scheme

2: SOCl2 View Scheme