1: diazoacetic acid ethyl ester With sodium hydride in tetrahydrofuran T=0 - 20°C; 2: phenylpropargyl aldehyde in tetrahydrofuran T=20°C; 24 h;

1.1: n-butyllithium / tetrahydrofuran; hexane / -78 °C / Inert atmosphere 1.2: -78 - 20 °C / Inert atmosphere 1.3: 0.5 h / 0 °C / Inert atmosphere 2.1: 1,8-diazabicyclo[5.4.0]undec-7-ene / acetonitrile / 20 °C View Scheme

1: 92 percent / manganese(IV) oxide / CH2Cl2 / 10 h / 20 °C 2: 92 percent / hydrogen / Lindlar catalyst / hexane / 1.5 h / 20 °C 3: 20 °C View Scheme