4,4-bis(ethoxycarbonyl)heptanedioic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (Kutsuma, T., Sugasawa, S., Tetrahedron, 3, 175 (1958).) To 100 mL of a pre-mixed solution of 10% (v/v) pyridine and acetic anhydride was added 4,4-bis(ethoxycarbonyl)heptanedioic acid (23.6 g, 78 mmol), and the resulting mixture heated at reflux in a pre-heated oil bath. The reaction was stirred for 3 hrs then cooled to room temperature and concentrated under reduced pressure. The resulting oil was azeotroped twice with CH2Cl2, then dissolved in 95% EtOH (300 mL) and water (300 mL) and treated with solid potassium carbonate (12.9 g, 93.6 mmol). The mixture was stirred for 16 hrs. The reaction was concentrated under reduced pressure to remove EtOH, and the remaining water layer was diluted to re-dissolve the solids, then extracted with Et2O (2×150 mL). The combined extracts were dried (MgSO4), filtered, and concentrated under reduced pressure, to afford the title compound (11.82 g, 48.8 mmol, 62.9% yield), as an amber oil. HPLC: 2.00 min (AP 74%); 1H NMR (500 MHz, CDCl3) δ ppm 4.24 (4H, q, J=7.12 Hz), 2.44 (4H, t, J=6.56 Hz), 2.37 (4H, t, J=6.41 Hz), 1.27 (6H, t, J=7.17 Hz). the resulting mixture heated at reflux in a pre-heated oil bath concentrated under reduced pressure The resulting oil was azeotroped twice with CH2Cl2 dissolved in 95% EtOH (300 mL) The mixture was stirred for 16 hrs The reaction was concentrated under reduced pressure to remove EtOH the remaining water layer was diluted to re-dissolve the solids extracted with Et2O (2×150 mL) The combined extracts were dried (MgSO4) filtered concentrated under reduced pressure