(E)-1,1-diethoxybut-2-ene

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

Procedure: A solution of (2E)-1,1-diethoxybut-2-ene (32.20 g, 223.27 mmol), (−)-diisopropyl D-tartrate (64.64 mL, 245.60 mmol) and pyridinium tosylate (2.24 g, 8.93 mmol) in 100 mL benzene was heated to 95° C. to distill off the solvent and EtOH produced. After 7 h at 95° C., the reaction was cooled to rt and concentrated in vacuo. Purification by normal phase chromatography (10->30% EtOAc/hexanes) yielded 35.37 g (55%) of diisopropyl (4S,5S)-2-[(1E)-prop-1-enyl]-1,3-dioxolane-4,5-dicarboxylate as an orange oil. 1H NMR (CDCl3, 400 MHz) 6.03 (m, 1H); 5.86 (m, 2H); 5.12 (m, 2H); 4.71 (d, J=3.84 Hz, 1H); 4.63 (d, J=3.84 Hz, 1H); 1.78 (m, 3H); 1.30 (d, J=6.23 Hz, 12H); LC/MS [M+H]+=287. to distill off the solvent and EtOH produced concentrated in vacuo Purification by normal phase chromatography (10->30% EtOAc/hexanes)