1.1: 81 percent / diisopropylethylamine; bis(2-oxo-3-oxazolidinyl)phosphinic chloride / toluene / 12 h / 85 °C 2.1: 73 percent / tetrabutylammonium fluoride / tetrahydrofuran / 52 h / 20 °C 3.1: CH2Cl2 / 0.17 h / 20 °C 3.2: 97 percent / K2CO3 / methanol / 1.25 h 4.1: 63 percent / aq. ceric ammonium nitrate / acetonitrile / 0.17 h / -10 °C View Scheme