1.1: 18-crown-6-ether; KN(TMS)2 / toluene; tetrahydrofuran / 0.08 h / -78 °C 1.2: 208 mg / tetrahydrofuran; toluene / 3 h / -78 °C 2.1: 92 percent / DIBAL-H / tetrahydrofuran; hexane / 1 h / -78 °C 3.1: 97 percent / DMSO; oxalyl chloride / CH2Cl2 / 0.5 h / -78 °C 4.1: toluene / 12 h / Heating 5.1: 83 percent / NaBH4; sulfur / tetrahydrofuran / 5 h / Heating 6.1: LiOH; H2O / methanol; tetrahydrofuran / 48 h / 20 °C 7.1: 81 percent / diisopropylethylamine; bis(2-oxo-3-oxazolidinyl)phosphinic chloride / toluene / 12 h / 85 °C 8.1: 73 percent / tetrabutylammonium fluoride / tetrahydrofuran / 52 h / 20 °C 9.1: CH2Cl2 / 0.17 h / 20 °C 9.2: 97 percent / K2CO3 / methanol / 1.25 h 10.1: 63 percent / aq. ceric ammonium nitrate / acetonitrile / 0.17 h / -10 °C View Scheme