1: 85 percent / diisopropylethylamine, dimethylaminopyridine / CH2Cl2 / 3 h / Ambient temperature 2: 98 percent / tetrabutylammonium fluoride / tetrahydrofuran / 2 h / Ambient temperature 3: 75 percent / pyridine / CH2Cl2 / -5 °C 4: 87 percent / sodium methoxide / CH2Cl2; methanol / 0.67 h / 0 °C 6: 65 percent / 2,6-di-tert-butyl-4-methylphenol / o-xylene / 144 h / Heating 7: 95 percent / 6 M HCl / tetrahydrofuran / 19 h / 40 °C 9: 68 percent / n-Bu3SnH, AIBN / toluene / 0.58 h / Heating 10: 94 percent / LAH / tetrahydrofuran / 0.5 h / 0 °C 11: 91 percent / pyridine / Ambient temperature 12: 85 percent / triethylamine / CH2Cl2 / 0.5 h / Ambient temperature 13: 90 percent / LAH / tetrahydrofuran / 0.67 h / 0 °C 14: 1.) oxalyl chloride, dimethylsulfoxide 2.) triethylamine / 1.) CH2Cl2, -10 deg C, 20 min 2.) -10 deg C, 5 min 15: 53 percent / K2CO3 / methanol / 19 h / 100 °C 16: 73 percent / sodium methoxide / methanol / 2 h / Ambient temperature 17: 85 percent / methanesulfonyl chloride, triethylamine / CH2Cl2 / 1 h / 0 °C 18: 90 percent / NaBH4 / propan-2-ol; CHCl3 / 0.67 h / Ambient temperature 19: 93 percent / aq.HF / acetonitrile / 24 h / Ambient temperature 20: 70 percent / DMAP / 0.33 h / 40 °C 21: 70 percent / Amberlyst A-21 / diethyl ether / 2 h / Ambient temperature 22: 55 percent / n-Bu3SnH, AIBN / toluene / 0.5 h / Heating 23: 0.034 g / sodium borohydride / propan-2-ol; tetrahydrofuran / -78 deg C to rt, overnight 24: 80 percent / n-tetrabutylammonium iodide, NaH / tetrahydrofuran / 18 h / Ambient temperature 25: 85 percent / 48percent aq. HF / acetonitrile / 1.5 h / Ambient temperature 26: 1.) oxalyl chloride, DMSO 2.) triethylamine / 1.) CH2Cl2, -60 deg C, 15 min 2.) -60 deg C, 15 min 27: 78 percent / BF3.Et2O, bis(trimethylsilyl)peroxide / CH2Cl2 / 1.5 h / Ambient temperature; 2 28: 42 percent / boron trichloride / CH2Cl2; hexane / 4 h / -78 °C View Scheme