Hydrogen Peroxide → (R)-2-(2-(tert-butoxy)-2-oxoethyl)pent-4-enoic acid

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Reaction Steps

In a 250 mL round-bottomed flask, (R)-tert-butyl 3-((S)-4-benzyl-2-oxooxazolidine-3-carbonyl)hex-5-enoate, Intermediate S8B (3.2 g, 8.57 mmol) was added to THF (30 mL) to give a colorless solution. The mixture was cooled on ice/water bath. In a 100 mL flask, LiOH (0.616 g, 25.7 mmol) was added to water (22 mL) to give a colorless solution. The LiOH mixture was cooled in an ice/water bath. Next, 30% H2O2 in water (2.183 mL, 21.38 mmol) was added to the LiOH mixture. The mixture was stirred at ice/water bath for another 10 min. The LiOH/H2O2 solution was added to the THF solution of starting material. The resulting reaction mixture was stirred in ice/water bath. The reaction was monitored by HPLC and was found to be complete after 30 min. The mixture was stirred for another 1.5 h. Next, 15 mL sat NaHCO3 was added, followed by the addition of ice and the slow addition of 20 mL saturated aqueous Na2SO3 to the mixture. The mixture was maintained at a temperature of less than 15° C. by the addition of ice. The mixture was stirred in the ice/water bath and periodically tested with a peroxide test strip until negative for peroxide. Water was added and the mixture was extracted with CH2Cl2 (3×). The aqueous layer was cooled with ice and acidified slowly with concentrated HCl to pH 4. EtOAc was added and solid NaCl was added very slowly with extensive bubbling. The organic layer was separated and the aqueous layer was twice extracted with EtOAc. The combined organic layers were washed twice with brine and then dried over MgSO4. The layer was filtered and concentrated to afford (R)-2-(2-(tert-butoxy)-2-oxoethyl)pent-4-enoic acid, Intermediate S8C (0.44 g, 2.054 mmol, 86% yield) as a clear colorless oil. 1H NMR (400 MHz, chloroform-d) δ 5.84-5.63 (m, 1H), 5.16-5.03 (m, 2H), 2.98-2.84 (m, 1H), 2.66-2.54 (m, 1H), 2.52-2.39 (m, 2H), 2.36-2.24 (m, 1H), 1.44 (s, 9H).

Provenance & Evidence