Potassium Hydroxide → (2S,3S)-3-(ethoxycarbonyl)oxirane-2-carboxylic acid

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Reaction Steps

An ethanolic solution of KOH (4.2 g, 64 mmol, in EtOH [50 ml]) was added dropwise to the 3a (9.7 g, 63 mmol) in EtOH (20 ml) at 0° C. for 30 min, and then the reaction was continued at r.t. for 8 h. The resulting viscous solution was diluted with ice water (150 ml), extracted with EA (2×200 ml). The aqueous layer was acidified with 1N HCl to pH˜4, and extracted with EA (3×150 ml). Combined organic extracts washed with brine (2×50 ml), dried over Na2SO4, and concentrated to afford the pure epoxide monoester 4 as colorless oil (8.9 g, 86.9%). 1H NMR (CDCl3, 400 MHz): δ 7.57 (br, 1H); 4.35-4.24 (m, 2H); 3.73 (s, 1H); 3.72 (s, 1H); 1.36-1.32 (t, 3H). 13C NMR (CDCl3, 100 MHz): 171.61, 166.40, 62.45, 52.20, 51.45, 13.89.

Provenance & Evidence