1.1: tetrahydrofuran; diethyl ether / -78 °C 1.2: NaOMe / methanol; tetrahydrofuran; diethyl ether / -78 - 20 °C 1.3: 72 percent / pentane / 20 °C 2.1: 72 percent / H2O2; NaOAc / tetrahydrofuran / 20 °C View Scheme

1: in N,N,N',N',N'',N''-hexamethylphosphoric triamide T=-78 - 20°C; 2: With sodium hydroxide; dihydrogen peroxide in tetrahydrofuran; methanol T=20°C; 4 h; Further stages.;