1: 88 percent / pyridinium p-toluene sulphonate / methanol / 48 °C 2: 90 percent / CrO3.2pyr,celite / CH2Cl2 / 0 °C 3: 62 percent / LDA / tetrahydrofuran / -78 - 25 °C 4: 66 percent / hydrogen / Lindlar 5: 95 percent / nBu4NF / tetrahydrofuran / 0 - 25 °C View Scheme

Multi-step reaction with 2 steps 1: 1.) nBuLi, TMEDA, THF, -78 degC, 2.) THF, -78 -> 25 degC2: 95 percent / imidazole / dimethylformamide / 0 - 25 °C  

With  pyridinium p-toluenesulfonate in  methanol T=48°C;   

Multi-step reaction with 2 steps 1: 88 percent / pyridinium p-toluene sulphonate / methanol / 48 °C2: 90 percent / CrO3.2pyr,celite / CH2Cl2 / 0 °C  

Multi-step reaction with 3 steps 1: 88 percent / pyridinium p-toluene sulphonate / methanol / 48 °C2: 90 percent / CrO3.2pyr,celite / CH2Cl2 / 0 °C3: 7 percent / LDA / tetrahydrofuran / -78 - 25 °C  

Multi-step reaction with 4 steps 1: 88 percent / pyridinium p-toluene sulphonate / methanol / 48 °C2: 90 percent / CrO3.2pyr,celite / CH2Cl2 / 0 °C3: 62 percent / LDA / tetrahydrofuran / -78 - 25 °C4: 66 percent / hydrogen / Lindlar