Yield:82486-43-9 80%

Reaction Conditions:

with pyridine;hydroxylamine hydrochloride in ethanol at 20; for 4 h;

Steps:

2 Example 2: (2S)-2-[4-bromo-2-(5-cyclopropyl-1,2-oxazol-3-yl)phenoxy]propanoic acid

Hydroxylamine hydrochloride (1.59 g, 22.88 mmol) was added to a stirred solution of 5-bromo-2-hydroxybenzaldehyde (2.1) (2.3 g, 11.44 mmol) and pyridine (2.78 ml, 34.3 mmol) in ethanol (20 ml) at room temperature. After 4 hours the mixture was diluted with water (200 ml), the solution was adjusted to pH 4-5 by addition of 1 M hydrochloric acid and stirred for 3 hours. The resulting precipitated solid was collected by filtration, washed with water (3×10 mL) and dried in vacuo at 45° C. for 3 days to afford (E)-5-bromo-2-hydroxybenzaldehyde oxime (2.2) (1.986 g, 9.14 mmol, 80% yield) as an off-white solid. The product was analysed by LCMS (Waters Acquity UPLC, X-Select, Waters X-Select UPLC C18, 1.7 μm, 2.1×30 mm, Acidic (0.1% Formic acid) 3 min method, 5-95% MeCN/water): m/z 216/218 (M+H)⁺ (ES⁺); at 1.268 min, 99.4% purity (diode array). 1H NMR (500 MHz, DMSO-d6) δ 11.48 (s, 1H), 10.31 (s, 1H), 8.27 (s, 1H), 7.65 (d, J=2.6 Hz, 1H), 7.37 (dd, J=8.7, 2.6 Hz, 1H), 6.86 (d, J=8.7 Hz, 1H).

References:

US2019/185437,2019,A1 Location in patent:Paragraph 1546-1547