2,6-dicarboxypyridinium chlorochromate in acetonitrile T=20°C; 0.25 h;

1.1: butyllithium / hexane; tetrahydrofuran / 2 h / 0 °C 1.2: 34 percent / tetrahydrofuran; hexane / 3 h 2.1: 85 percent / aq. hydrochloric acid / 4 h / Heating View Scheme