1: 60 percent / CrO3-H2SO4 / acetone / 0 °C / Jones oxidation 2: 88 percent / DBU / diethyl ether / Ambient temperature View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1: 60 percent / NaH-HMPA / Peterson olefination<br />2: 93 percent / silica gel (Wako Gel C-200) / hexane / 10 h / Heating<br />3: 64 percent / 30percent H₂SO₄ / acetone / 20 h / Ambient temperature<br /> <br /> &nbsp;

<b>Multi-step reaction with 5 steps<br /> </b>1: LDA<br />3: 60 percent / NaH-HMPA / Peterson olefination<br />4: 93 percent / silica gel (Wako Gel C-200) / hexane / 10 h / Heating<br />5: 64 percent / 30percent H₂SO₄ / acetone / 20 h / Ambient temperature<br /> <br /> &nbsp;