1.1: toluene-4-sulfonic acid / dichloromethane / 96 h / 20 °C / |Inert atmosphere 2.1: sodium hydride / hexane; tetrahydrofuran / 1 h / -15 °C / |Inert atmosphere 2.2: 20 °C / |Inert atmosphere 3.1: sodium hydride / hexane; tetrahydrofuran / 1 h / -15 °C / |Inert atmosphere 3.2: 20 °C / |Inert atmosphere 4.1: potassium hydroxide / ethanol; water / 12 h / |Inert atmosphere; |Reflux 4.2: 2 h / pH 2 / |Inert atmosphere; |Reflux 5.1: diisobutylaluminium hydride / diethyl ether; toluene / 0.5 h / -78 °C / |Inert atmosphere 6.1: toluene-4-sulfonic acid / dichloromethane / 0 - 20 °C / |Inert atmosphere 6.2: 4 h / |Inert atmosphere; |Reflux View Scheme