1.1: NEt3; PivCl / tetrahydrofuran / 1 h / 0 °C 1.2: 94.5 percent / LiCl / tetrahydrofuran / 0 - 20 °C 2.1: TMEDA / CH2Cl2 / 2 h / 0 °C 2.2: 78.7 percent / CH2Cl2 / 0 °C 3.1: 96.7 percent / 2,6-lutidine / dimethylformamide / 24 h / 20 °C 4.1: 95.9 percent / LiBH4 / diethyl ether; methanol; tetrahydrofuran / 0 °C 5.1: 95.8 percent / i-Pr2NEt; Py*SO2 / CH2Cl2; dimethylsulfoxide / 0.25 h / 0 °C 6.1: 97.8 percent / TsOH / methanol / 1 h / 20 °C 7.1: 97.1 percent / PPTS / benzene / Heating 8.1: 89.4 percent / NaHCO3; I2 / acetone; H2O / 0.25 h / 0 °C 9.1: LDA / tetrahydrofuran; hexane / 1 h / -78 °C 9.2: tetrahydrofuran; hexane / -78 - 20 °C 10.1: 2.25 g / TiCl4 / CH2Cl2 / 1 h / -78 °C 11.1: 97 percent / DBU / methanol / 1 h / 0 °C 12.1: BuLi / tetrahydrofuran; hexane / 1 h / -78 °C 12.2: MeCuCNLi / tetrahydrofuran; hexane; diethyl ether / 1 h / -78 °C 12.3: 92.6 percent / tetrahydrofuran; hexane; diethyl ether / 1 h / -78 °C 13.1: 131 mg / (S)-2-methyl-CBS-oxazaborolidine; BH3*Me2S / tetrahydrofuran; toluene / 0.25 h / 0 °C 14.1: 96.4 percent / diethyl ether / 1 h / 0 °C 15.1: 72 percent / Li-naphthalene / tetrahydrofuran / -25 °C 16.1: MnO2 / CH2Cl2 / 3 h / Heating 17.1: 33.6 mg / NaH2PO4; 2-methyl-2-butene; NaClO2 / 2-methyl-propan-2-ol; H2O / 20 °C 18.1: NEt3; 2,4,6-trichlorobenzoyl chloride / tetrahydrofuran / 6 h 18.2: 81 percent / DMAP / tetrahydrofuran; toluene / Heating 19.1: 91 percent / aq. HCl / tetrahydrofuran; H2O / 48 h / 20 °C View Scheme

1: 1.) 3-(5-nitro-2-oxo-1,2-dihydro-1-pyridyl)-1,2-benzisothiazole 1,1-dioxide (BID-NPy), triethylamine (TEA) / 1.) CH2Cl2, 0 deg C, 1.5 h, 2.) CH2Cl2, RT, 30 min 2: 1.) BuLi / 1.) THF, -78 to -20 deg C, 2 h, 2.) THF, RT, overnight 3: 1.) LDA / 1.) THF, -78 deg C to RT, 3 h, 2.) THF, RT, overnight 4: p-toluenesulfonic acid (PTSA), boric acid / toluene / 0.5 h / Heating 5: 89 percent / CuCl2*2H2O, CuO / acetone / 1 h / Heating View Scheme