oxalyl dichloride; dimethyl sulfoxide; triethylamine in tetrahydrofuran T=-78 - 0°C; Swern reaction;

potassium tert-butylate in dimethyl sulfoxide T=80°C; 1.5 h;

tetrabutyl ammonium fluoride; sodium hydride in tetrahydrofuran Heating;

potassium hydroxide T=110°C; 4 h;

1: 98 percent / BH3*Me2S / tetrahydrofuran / 4 h / 50 °C 2: 61 percent Turnov. / KOH (powdered) / 5 h / 110 °C View Scheme

1: oxalyl chloride; DMSO; triethylamine / tetrahydrofuran / -78 - 0 °C 2: 1.69 g / tetrahydrofuran; diethyl ether / -78 - 20 °C View Scheme

1: oxalyl chloride; DMSO; triethylamine / tetrahydrofuran / -78 - 0 °C 2: 1.69 g / tetrahydrofuran; diethyl ether / -78 - 20 °C 3: oxalyl chloride; DMSO; triethylamine / tetrahydrofuran / -78 - 0 °C 4: 1.86 g / tetrahydrofuran; diethyl ether / -78 - 20 °C View Scheme