1.1: HMPA / tetrahydrofuran / 0.25 h / -30 °C 1.2: Pb(OAc)4; AcOH / CH2Cl2; tetrahydrofuran / -30 - 20 °C 1.3: NaOH / CH2Cl2 / 0.5 h / 20 °C 2.1: tris(dimethylamino)methane / dimethylformamide / 3 h / 105 °C 2.2: 70 percent / KMnO4 / tetrahydrofuran; H2O / 3 h / 20 °C 3.1: Na2S2O4 / tetrahydrofuran; H2O / 1 h / 50 °C 4.1: 2.6 g / N,N-dimethyl-acetamide / 4 h / 150 °C View Scheme

1.1: tris(dimethylamino)methane / dimethylformamide / 3 h / 105 °C 1.2: 70 percent / KMnO4 / tetrahydrofuran; H2O / 3 h / 20 °C 2.1: Na2S2O4 / tetrahydrofuran; H2O / 1 h / 50 °C 3.1: 2.6 g / N,N-dimethyl-acetamide / 4 h / 150 °C View Scheme

1: Na2S2O4 / tetrahydrofuran; H2O / 1 h / 50 °C 2: 2.6 g / N,N-dimethyl-acetamide / 4 h / 150 °C View Scheme

in N,N-dimethyl acetamide T=150°C; 4 h;