dibenzo-18-crown-6; potassium bromide; copper(ll) bromide; 1,10-phenanthroline; copper(I) bromide in acetonitrile T=20°C; Sandmeyer bromination; 0.333333 h;

1: With diisopropylamine in tetrahydrofuran; hexane T=-75°C; 2 h; 2: With n-butyllithium in tetrahydrofuran; diethyl ether; hexane T=-100°C; 0.25 h; 3: With n-butyllithium in diethyl ether; hexane T=-100°C; 0.25 h;

(i) NaNO2, aq. HCl, (ii) CuCl; Multistep reaction;

1: With diisopropylamine in tetrahydrofuran; hexane T=-75°C; 2 h; 2: With n-butyllithium in tetrahydrofuran; diethyl ether; hexane T=-100°C; 0.25 h; Title compound not separated from byproducts;

1.1: diisopropylamine; butyllithium / hexane; tetrahydrofuran / 2 h / -75 °C 1.2: 89 percent / hexane; tetrahydrofuran 2.1: 96 percent / bromine / CCl4 / 12 h / Heating 3.1: diisopropylamine / hexane; tetrahydrofuran / 2 h / -75 °C 3.2: butyllithium / tetrahydrofuran; diethyl ether; hexane / 0.25 h / -100 °C 3.3: 49 percent / butyllithium / hexane; diethyl ether / 0.25 h / -100 °C View Scheme

1.1: 96 percent / bromine / CCl4 / 12 h / Heating 2.1: diisopropylamine / hexane; tetrahydrofuran / 2 h / -75 °C 2.2: butyllithium / tetrahydrofuran; diethyl ether; hexane / 0.25 h / -100 °C 2.3: 49 percent / butyllithium / hexane; diethyl ether / 0.25 h / -100 °C View Scheme

1.1: diisopropylamine; butyllithium / hexane; tetrahydrofuran / 2 h / -75 °C 1.2: 89 percent / hexane; tetrahydrofuran 2.1: diisopropylamine; butyllithium / hexane; tetrahydrofuran / 2 h / -75 °C 2.2: 89 percent / hexane; tetrahydrofuran 3.1: 96 percent / bromine / CCl4 / 12 h / Heating 4.1: diisopropylamine / hexane; tetrahydrofuran / 2 h / -75 °C 4.2: butyllithium / tetrahydrofuran; diethyl ether; hexane / 0.25 h / -100 °C 4.3: 49 percent / butyllithium / hexane; diethyl ether / 0.25 h / -100 °C View Scheme

1: 5-bromo-1,2,3-trichlorobenzene With n-butyllithium in tetrahydrofuran; hexane T=-75°C; 0.25 h; 2: carbon dioxide in tetrahydrofuran; hexane