diethyl (2S,3S)-oxirane-2,3-dicarboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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. extracted with EA (2×200 ml) extracted with EA (3×150 ml) Combined organic extracts washed with brine (2×50 ml) dried over Na2SO4 concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Followed general procedure for 3a using the following quantities: 2b (34.6 g, 129 mmol): Et2O (100 ml); DBU (29.4 g, 193 mmol, in Et2O [50 ml]); yielded 3b as a colorless oil (18.1 g, 74.8%). 1H NMR (CDCl3, 400 MHz): δ 4.36-4.22 (m, 4H); 3.67 (s, 2H); 1.35-1.31 (t, 6H). 13C NMR (CDCl3, 100 MHz): 166.75, 62.21, 52.01, 14.01.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2a (38.1 g, 142 mmol) was dissolved in anhydrous Et2O (100 ml) and DBU (32.3 g, 212.4 mmol, in Et2O [50 ml]) was added dropwise at 0° C. for 1 h. The reaction was allowed to warm to r.t. and stirred for an additional 4 h. Reaction was quenched with cold 1N HCl to pH˜5. The resulting aqueous layer was extracted with Et2O (3×150 ml). The combined organic extracts were washed with brine (2×100 ml), dried over Na2SO4, and concentrated to give the pure product as faintly yellow oil (21.5 g, 80.7% yield). Product purity typically reflects that of the bromohydrin starting material. If necessary, fractional vacuum distillation can be used for purification. 1H NMR (CDCl3, 400 MHz): δ 4.36-4.22 (m, 4H); 3.67 (s, 2H); 1.35-1.31 (t, 6H). 13C NMR (CDCl3, 100 MHz): 166.75, 62.21, 52.01, 14.01. Reaction was quenched with cold 1N HCl to pH˜5 The resulting aqueous layer was extracted with Et2O (3×150 ml) The combined organic extracts were washed with brine (2×100 ml) dried over Na2SO4 concentrated