[Synthesis]
The general procedure for the synthesis of 7-(tert-butoxy)-7-oxoheptanoic acid from heptanedioic acid and tert-butanol was as follows: heptanedioic acid (1.56 mL, 12.5 mmol), 2-methyl-2-propanol (14.9 mL, 156.3 mmol), EDCI (2.4 g, 12.5 mmol) and DMAP (1.53 g, 12.5 mmol) were dissolved in dichloromethane (15 mL). The reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the reaction mixture was diluted with ether (60 mL) and washed sequentially with 0.01 N aqueous HCl and deionized water. The organic phase was dried with anhydrous magnesium sulfate and subsequently concentrated under reduced pressure to remove the solvent. The crude product was purified by column chromatography (eluent ratio 1:1 ethyl acetate:petroleum ether) to afford 7-(tert-butoxy)-7-oxoheptanoic acid (0.52 g, 2.42 mmol, 19% yield) as a colorless oil.1H NMR (400 MHz, DMSO-d6) δ ppm: 12.42 (br s, 1H), 2.18 (q, J = 7.4 Hz, 4H), 1.54-1.43 (m, 4H), 1.40 (s, 9H), 1.32-1.22 (m, 2H). |