1: 4-bromo-1-chloroisoqionoline With tert.-butyl lithium in tetrahydrofuran; hexane T=-80°C; Inert atmosphere; 2: carbon dioxide in tetrahydrofuran

1: sodium tungstate monohydrate; dihydrogen peroxide; acetic acid / 3 h / 80 °C 2: trichlorophosphate / N,N-dimethyl-formamide; toluene / 20 °C / Inert atmosphere; Cooling with ice 3: tert.-butyl lithium / tetrahydrofuran; hexane / -80 °C / Inert atmosphere View Scheme

1: trichlorophosphate / N,N-dimethyl-formamide; toluene / 20 °C / Inert atmosphere; Cooling with ice 2: tert.-butyl lithium / tetrahydrofuran; hexane / -80 °C / Inert atmosphere View Scheme