N,N-dimethyl-formamide in methanol; water 1 h;

N,N-dimethyl-formamide dimethyl acetal in DMF (N,N-dimethyl-formamide) 1 h;

1.1: 70 percent / H2 / Raney Ni / ethyl acetate 2.1: 96 percent / 2-methyl-propan-2-ol / 4 h / 40 °C 3.1: n-BuLi; tetramethylethylenediamine / diethyl ether / -78 °C 3.2: diethyl ether 4.1: methanol; CHCl3; hexane / 2 h / 0 - 20 °C 5.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 5.2: AcOH / tetrahydrofuran / -78 - 20 °C 6.1: dimethylformamide / 5 h / 20 °C View Scheme

1.1: 84 percent / KF / dimethylsulfoxide / 18 h / 70 °C 2.1: 70 percent / H2 / Raney Ni / ethyl acetate 3.1: 96 percent / 2-methyl-propan-2-ol / 4 h / 40 °C 4.1: n-BuLi; tetramethylethylenediamine / diethyl ether / -78 °C 4.2: diethyl ether 5.1: methanol; CHCl3; hexane / 2 h / 0 - 20 °C 6.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 6.2: AcOH / tetrahydrofuran / -78 - 20 °C 7.1: dimethylformamide / 5 h / 20 °C View Scheme

1.1: 96 percent / 2-methyl-propan-2-ol / 4 h / 40 °C 2.1: n-BuLi; tetramethylethylenediamine / diethyl ether / -78 °C 2.2: diethyl ether 3.1: methanol; CHCl3; hexane / 2 h / 0 - 20 °C 4.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 4.2: AcOH / tetrahydrofuran / -78 - 20 °C 5.1: dimethylformamide / 5 h / 20 °C View Scheme

1.1: n-BuLi; tetramethylethylenediamine / diethyl ether / -78 °C 1.2: diethyl ether 2.1: methanol; CHCl3; hexane / 2 h / 0 - 20 °C 3.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 3.2: AcOH / tetrahydrofuran / -78 - 20 °C 4.1: dimethylformamide / 5 h / 20 °C View Scheme

1.1: methanol; CHCl3; hexane / 2 h / 0 - 20 °C 2.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 2.2: AcOH / tetrahydrofuran / -78 - 20 °C 3.1: dimethylformamide / 5 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran / 1 h / -78 °C 1.2: AcOH / tetrahydrofuran / -78 - 20 °C 2.1: dimethylformamide / 5 h / 20 °C View Scheme

oxalyl dichloride; N,N-dimethyl-formamide in dichloromethane 3 h; Heating / reflux;

1: 70 percent / (COCl)2; DMF / CH2Cl2 / 2 h / Heating 2: ethanol / 8 h / Heating View Scheme