1.1: sodium hydride / mineral oil; tetrahydrofuran / 0.5 h / 0 - 20 °C / |Inert atmosphere 1.2: 0.5 h / |Inert atmosphere 2.1: thiourea / ethanol / 4 h / 20 °C / |Inert atmosphere; |Reflux 2.2: 2 h / |Inert atmosphere; |Reflux 3.1: zinc; nickel dichloride; pyridine; MeCH=CHCO2Et / methanol / 20 °C / |Inert atmosphere View Scheme