1.1: sodium tetrahydroborate / ethanol / 20 °C / Inert atmosphere; Cooling with acetone-dry ice 1.2: Inert atmosphere 2.1: n-butyllithium; diisopropylamine / tetrahydrofuran; hexane / -78 °C / Inert atmosphere; Reflux 3.1: potassium carbonate / acetone / 6 h / Inert atmosphere; Reflux View Scheme