Potassium Hydroxide → 5-Methoxy-4,4-dimethyl-5-oxopentanoic acid

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Reaction Steps

To a solution of 2,2-dimethyl-pentanedioic acid dimethyl ester (2.40 g, 12.8 mmol) in MeOH (15 ml) is added potassium hydroxide (0.788 g, 14.0 mmol). The mixture is stirred at room temperature for 16 hours and refluxed for 2 hours. The mixture is cooled to room temperature and concentrated under reduced pressure. To the obtained residue, 1M aqueous HCl (14 ml) is added and the solution is extracted with ether. The organic layer is washed with H2O, dried over Na2SO4, and concentrated under reduced pressure to give 2,2-dimethyl-pentanedioic acid 1-methyl ester (1.97 g, 88%); 1H NMR (400 MHz, chloroform-d) ppm 1.20 (s, 6H), 1.87-1.91 (m, 2H), 2.32-2.36 (m, 2H), 3.67 (s, 3H). To a suspension of 2,2-dimethyl-pentanedioic acid 1-methyl ester (1.00 g, 5.75 mmol) in THF (3 mL), 1M LiBHEt3 in THF (38.0 ml, 38.0 mmol) is added dropwise maintaining the temperature below 10° C. under nitrogen. The mixture is stirred at 10° C. for 1 hour. To the mixture, 50% AcOH (4.6 mL) and H2O are added. The solution is extracted with AcOEt, and the organic layer is washed with H2O, dried over MgSO4, and concentrated under reduced pressure to give 5-hydroxy-4,4-dimethyl-pentanoic acid (850 mg, quant.); 1H NMR (400 MHz, chloroform-d) ppm 1.06 (s, 6H), 1.70 (t, 2H), 2.56 (t, 2H), 3.98 (s, 2H).

Provenance & Evidence