sulfuric acid T=20°C; 21 h;

1.1: sodium tetrahydroborate; boron trifluoride diethyl etherate / tetrahydrofuran / 1 h / 0 °C / |Inert atmosphere 1.2: |Inert atmosphere 2.1: triethylamine / dichloromethane / 0 - 20 °C / |Inert atmosphere 3.1: cesium hydroxide monohydrate / N,N-dimethyl-formamide / 0 °C / |Inert atmosphere 3.2: 0 - 20 °C / |Inert atmosphere 4.1: phenyllithium / tetrahydrofuran; hexane / 1.5 h / -78 - 20 °C / |Inert atmosphere View Scheme