1: 72 percent / NaH-HMPA / Peterson olefination 2: 94 percent / silica gel (Wako Gel C-200) / hexane / 10 h / Heating 3: 65 percent / 30percent H2SO4 / acetone / 20 h / Ambient temperature; thioallylic rearrangement of methoxyallyl sulfides to α-methylene-γ-butyrolactones 4: 76 percent / CrO3-H2SO4 / acetone / 0 °C / Jones oxidation 5: 79 percent / DBU / diethyl ether / Ambient temperature View Scheme

<b>Multi-step reaction with 2 steps<br /> </b>1: LDA<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: LDA<br /> <br /> &nbsp;