2-Cyclopentene-1,4-dione → 2-(alpha-Methoxypropylidene)cyclopent-4-ene-1,3-dione

Beteiligte Stoffe

Reaktionsschritte

To a suspension of cyclopent-4-ene-1,3-dione (1.22 g, 12.6 mmol) in acetic anhydride (4 ml) were added ethyl orthobutyrate (3.74 g, 25.3 mmol) and anhydrous ZnCl2. The reaction was heated at 80° for 24 h, solid removed by filtration, the filtrate concentrated in vacuo and the residues purified by chromatography (SiO2; 70:30 hexane/EtOAc) to give 2-(α-methoxypropylidene)cyclopent-4-ene-1,3-dione as a brown oil. δ H (CDCl3) 6.88 (2H, s), 4.07 (3H, s), 3.00 (2H, t), 1.63 (2H, m), 1.08 (3H, t). m/z (ESI, 70V) 181 (MH+).

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