Diisopropylcarbodiimide → HCID 131725968, compound

Participants

Reaction Steps

Diisopropylcarbodiimide (3.16 g, 25.17 mmol) was added to a solution of (2S,4EZ)-1-(tert-butoxycarbonyl)-4-(methoxyimino)-2-pyrrolidine-carboxylic acid (Intermediate 2, 6.50 g, 25.17 mmol) and acetamidoxime (Intermediate 7, 1.86 g, 25.17 mmol) in DCM (55 ml) and stirred overnight at room temperature (DCM-insoluble amidoximes were pre-dissolved in THF, to which was added a solution of DIC and Intermediate 2 in DCM). After filtering at the pump, and evaporation in vacuo, the residue was dissolved in pyridine (60 ml) and refluxed for one hour, then cooled and allowed to stand overnight, then evaporated in vacuo. The crude product was then dissolved in DCM (50 ml) and washed with sat. NaHCO3(aq) (2×50 ml) and then 1M HCl(aq) (2×50 ml), dried over magnesium sulphate and evaporated in vacuo (crude yield 70%). Silica gel chromatography, eluting with 15% ethyl acetate in hexanes gave the desired compound, tert-butyl (2S,4EZ)-4-(methoxyimino)-2-(3-methyl-1,2,4-oxadiazol-5-yl)-1-pyrrolidinecarboxylate (4.4 g, 60% yield).

Provenance & Evidence