boron trifluoride diethyl etherate in dichloromethane T=20°C; 63.5667 h; other reaction time; also with other HX (X =Cl, OH); also in the absence of BF3*Et2O; Product distribution;

F-4SK (H form) T=100°C; 10 h;

N-benzyl-N,N,N-triethylammonium chloride in N,N-dimethyl-formamide T=110 - 115°C; 7 h;

1: 85 percent / triethylbenzylammonium chloride / dimethylformamide / 24 h / 100 - 105 °C / other catalyst 2: 65 percent / KOH / triethylbenzylammonium chloride / benzene / 12 h / 80 °C 3: 50 percent / β-naphtol, sodium methoxide / methanol / 3 h / 64 °C View Scheme

1: 85 percent / triethylbenzylammonium chloride / dimethylformamide / 24 h / 100 - 105 °C / other catalyst 2: 65 percent / KOH / triethylbenzylammonium chloride / benzene / 12 h / 80 °C View Scheme