1.1: 46.7 percent / MgBr2 / diethyl ether / 20 °C 2.1: 66.4 percent / anhydrous K2CO3 / dimethylformamide / 36 h / 20 °C 3.1: 97 percent / PPTS / CH2Cl2 / 7 h / 20 °C 4.1: Grubbs' second generation metathesis catalyst / CH2Cl2 / 0.5 h / Heating 4.2: ethyl vinyl ether / CH2Cl2 / 0.25 h 4.3: 21 mg / N-methylquinolinium hexafluorophosphate; sodium acetate; anhydrous sodium thiosulfate / O2 / 1,2-dichloro-ethane; toluene / 5 h / 20 °C / Irradiation View Scheme