1: 5-bromo-7-fluoroindole With n-butyllithium in tetrahydrofuran; hexane T=-75°C; 2: carbon dioxide in tetrahydrofuran; hexane cooling;

1: With n-butyllithium in tetrahydrofuran; hexane T=-60°C; 4 h; 2: With carbon dioxide in tetrahydrofuran; hexane; water pH=4;

LiOH in methanol; water

1.1: 76 percent / N-bromosuccinimide / CHCl3 / 2 h / 25 °C 2.1: 72 percent / hydrogen peroxide; water / trifluoroacetic acid / 1 h / Heating 3.1: 36 percent / tetrahydrofuran / -40 °C 4.1: BuLi / hexane; tetrahydrofuran / -75 °C 4.2: 58 percent / hexane; tetrahydrofuran / cooling View Scheme

1.1: 72 percent / hydrogen peroxide; water / trifluoroacetic acid / 1 h / Heating 2.1: 36 percent / tetrahydrofuran / -40 °C 3.1: BuLi / hexane; tetrahydrofuran / -75 °C 3.2: 58 percent / hexane; tetrahydrofuran / cooling View Scheme

1.1: 36 percent / tetrahydrofuran / -40 °C 2.1: BuLi / hexane; tetrahydrofuran / -75 °C 2.2: 58 percent / hexane; tetrahydrofuran / cooling View Scheme