in diethyl ether T=0°C; 0.5 h;

1: 1) NaOMe / 1) methanol, 2) methanol, reflux, overnight 2: 94 percent / 25percent aqueous KOH / 2 h / Heating 3: 70 percent / dimethylformamide / 1 h / Heating 4: 83 percent / oxalylchloride / hexane / 1 h / Heating 5: 100 percent / diethyl ether / 0.5 h / 0 °C View Scheme

1: 94 percent / 25percent aqueous KOH / 2 h / Heating 2: 70 percent / dimethylformamide / 1 h / Heating 3: 83 percent / oxalylchloride / hexane / 1 h / Heating 4: 100 percent / diethyl ether / 0.5 h / 0 °C View Scheme

1: 83 percent / oxalylchloride / hexane / 1 h / Heating 2: 100 percent / diethyl ether / 0.5 h / 0 °C View Scheme

1: 70 percent / dimethylformamide / 1 h / Heating 2: 83 percent / oxalylchloride / hexane / 1 h / Heating 3: 100 percent / diethyl ether / 0.5 h / 0 °C View Scheme

1: 86 percent / 25 percent aqueous KOH / methanol / 2 h / Heating 2: 83 percent / oxalylchloride / hexane / 1 h / Heating 3: 100 percent / diethyl ether / 0.5 h / 0 °C View Scheme