1: 65 percent / tetrabutylammonium hydroxide, pyridine / acetonitrile / 48 h / Heating 2: 1.) NaH / 1.) DMF, -40 deg C, 0.75 h, 2.) DMF, a) from -40 to -30 deg C, 0.75 h, b) RT, 4 h 3: 71 percent / potassium t-butoxide / CH2Cl2 / 1.5 h / Ambient temperature 4: 40 percent / HCl / CH2Cl2; methanol / 0.75 h / Ambient temperature View Scheme

1: pyridine / CH2Cl2 / 1) ice-bath, 15 min; 2) 20 deg C, 3 h 2: aq. NaOH / ethanol / 1 h / 60 °C 3: 75 percent / LiEt3BH / tetrahydrofuran / 1) dry ice/acetone cooling, 1 h; 2) 20 deg C, 1 h 4: 74 percent / aq. AcOH / 0.5 h / 22 °C View Scheme

1: pyridine / CH2Cl2 / 1) ice-bath, 15 min; 2) 20 deg C, 3 h 2: aq. NaOH / ethanol / 1 h / 60 °C 3: 75 percent / LiEt3BH / tetrahydrofuran / 1) dry ice/acetone cooling, 1 h; 2) 20 deg C, 1 h View Scheme

1: 65 percent / tetrabutylammonium hydroxide, pyridine / acetonitrile / 48 h / Heating 2: 1.) NaH / 1.) DMF, -40 deg C, 0.75 h, 2.) DMF, a) from -40 to -30 deg C, 0.75 h, b) RT, 4 h 3: 71 percent / potassium t-butoxide / CH2Cl2 / 1.5 h / Ambient temperature 4: 75 percent / diisopropylethylamine / tetrahydrofuran / 4.5 h View Scheme