Hydrochloric Acid → 5-(Propan-2-yl)-1,2-oxazol-3-amine

Temperature

120 °C

N′-Hydroxy-2-(2-isopropyl-1,3-dioxolan-2-yl)acetimidamide (1.8 g, 9.57 mmol) was dissolved in ethanol (12 ml) and acidified to pH=1 with 37% aqueous hydrochloric acid. The mixture was subjected to microwave heating at 120° C. for 30 minutes. After concentration under reduced pressure the residue was diluted with dichloromethane, a solution of saturated sodium bicarbonate was added until the solution became basic (pH=11) and the organic layer separated. After multiple extractions of the water phase with dichloromethane, the organic layers were combined, dried (MgSO4), filtered and concentrated under reduced pressure. The crude material was purified by silica gel chromatography (hexane/ethyl acetate 1:1) to afford 5-isopropylisoxazol-3-amine (819 mg, 68%). 1H NMR (300 MHz, CDCl3) δ 5.52 (s, 1H), 3.89 (bs, 2H), 2.96-2.91 (m, 1H), 1.27 (d, 6H); LC-MS (ESI) m/z 127 (M+H)+.

1. concentrationAfter concentration under reduced pressure the residue
2. additionwas diluted with dichloromethane
3. additiona solution of saturated sodium bicarbonate was added until the solution
4. customthe organic layer separated
5. extractionAfter multiple extractions of the water phase with dichloromethane
6. dry with materialdried (MgSO4)
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure
9. customThe crude material was purified by silica gel chromatography (hexane/ethyl acetate 1:1)

ORD record

ord-ca1400ecc6454becb1a51a5a53ab95a4

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08618289B2