反应详情

A solution of KOH (25 g) in water (50 mL) was added to a solution of 2,2,14,14-tetramethyl-8-oxo-pentadecanedioic acid diethyl ester (10.69 g, 155 mmol) in ethanol (400 mL), then heated at reflux for 4 h. After cooling, the solution was evaporated to a volume of ca. 50 mL and diluted with water (800 mL). The organic impurities were removed by extracting with dichloromethane (2×200 mL). The aqueous layer was acidified to pH 2 with concentrated hydrochloric acid (50 mL) and extracted with methyl tert.-butyl ether (MTBE, 3×200 mL). The combined organic layers were dried over magnesium sulfate and concentrated in vacuo to give the crude product (9.51 g) as an oil. Crystallization from hexanes/MTBE (50 mL: 25 mL) afforded 8-oxo-2,2,14,14-tetramethylpentadecanedioic acid (6.92 g, 79%) as waxy, white crystals. M.p.: 83-84° C. 1H NMR (300 MHz, CDCl3/TMS): δ (ppm): 12.03 (s, 2H), 2.37 (t, 4H, J=7.3 Hz), 1.52-1.34 (m, 8H), 1.28-1.10 (m, 8H), 1.06 (s, 12H). 13C NMR (75 MHz, CDCl3/TMS): (ppm): 210.5, 178.8, 41.7, 41.2, 29.1, 25.0, 24.4, 23.1. HRMS (LSIMS, gly): Calcd. for C19H35O5 (MH+): 343.2484. found: 343.2485.

1. temperatureheated
2. temperatureat reflux for 4 h
3. temperatureAfter cooling
4. customthe solution was evaporated to a volume of ca. 50 mL
5. additiondiluted with water (800 mL)
6. customThe organic impurities were removed
7. extractionby extracting with dichloromethane (2×200 mL)
8. extractionextracted with methyl tert.-butyl ether (MTBE, 3×200 mL)
9. dry with materialThe combined organic layers were dried over magnesium sulfate
10. concentrationconcentrated in vacuo
11. customto give the crude product (9.51 g) as an oil
12. customCrystallization from hexanes/MTBE (50 mL: 25 mL)