4-O-tert-butyl 1-O-ethyl (E)-but-2-enedioate

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

Procedure: 4-1 (340 mg, 1.7 mmol) was stirred for 1 h at rt with a solution comprised of 4 mL THF, and 4 mL of a solution containing 1 M NaOH and 1 M LiCl. The resulting mixture was acidified to pH 3-4 with 1 M KHSO4 and extracted twice with 30 mL of EtOAc. The extract was washed with 30 mL of brine, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting material was subjected to silica gel flash chromatography using a gradient of 5–10% methanol in DCM to yield 240 mg (82% yield) of 4-2. extracted twice with 30 mL of EtOAc The extract was washed with 30 mL of brine dried over magnesium sulfate concentrated under reduced pressure

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

Procedure: To a solution of fumaric acid mono-ethyl ester (721 mg, 5 mmol) and tert-butanol (0.938 mL, 10 mmol) in 10 mL of DCM was added DMAP (122 mg, 1 mmol) followed by DCC (2.06 g, 10 mmol). The resulting mixture was stirred at rt for 16 h, taken to dryness under reduced pressure, stirred overnight with 50 mL acetone and filtered to remove DCU. The resulting filtrate was concentrated under reduced pressure, and the residue taken up in EtOAc. The EtOAc was washed twice with 30 mL 0.1 M KHSO4, and once with 30 mL saturated NaHCO3 and once with 30 mL of brine. The resulting EtOAc solution was treated with charcoal and dried over magnesium sulfate, concentrated under reduced pressure, and subjected to silica gel flash chromatography using a gradient of 0–15% EtOAc in hexanes as eluent to give essentially pure (one peak on HPLC) 4-1 (350 mg, 35% yield). filtered to remove DCU The resulting filtrate was concentrated under reduced pressure The EtOAc was washed twice with 30 mL 0.1 M KHSO4 The resulting EtOAc solution was treated with charcoal dried over magnesium sulfate concentrated under reduced pressure