Diisopropylethylamine → HCID 178451982、化合物

To 3-(3-hydroxyisoxazol-5-yl)propanoic acid (300 mg, 1.909 mmol) in DMF (7 mL) was added DIPEA (0.667 mL, 3.82 mmol) followed by 1-[(1-(cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylaminomorpholino)]uronium hexafluorophosphate (COMU) (981 mg, 2.291 mmol). The resulting brown solution was stirred at RT for 5 mins and then treated with 1-BOC-4-(aminomethyl)piperidine (409 mg, 1.909 mmol). After stirring at RT for 2 hrs, the solution was concentrated under reduced pressure and the residue suspended in 0.2M aqueous HCl (200 ml). The mixture was extracted with EtOAc (2×100 ml) and the combined extracts were dried (MgSO4) and concentrated under reduced pressure. The crude residue was dissolved in DCM (100 ml) and treated with 2M NaOH (50 ml). The mixture was stirred vigorously at ambient temperature for 16 hrs. The mixture was then acidified with citric acid and the organics removed, dried (MgSO4) and concentrated under reduced pressure. The residue was applied to a 24 g silica cartridge and eluted with 0-100% EtOAc/iso-hexane. The product fractions were combined and concentrated to give a tert-butyl 4-((3-(3-hydroxyisoxazol-5-yl)propanamido)methyl)piperidine-1-carboxylate as a gum.