Ethyl 3-bromoisoxazole-5-carboxylate

b.p. 80° C. at 0.5 mmHg. 1 H-NMR (CDCl3, TMS). delta (ppm)=7.10 (s, H isoxazole); 4.5 (q, CH2 --CH3); 1.8 (t, CH2 -CH3).Dibromoformaldoxime (407 mg, 2.07 mmol) (prepared via the procedure of JC Rohloff, et. al., Tetrahedron Lett 1992, 33 : 3113-6), and ethyl propiolate (311 mg, 3.17 mmol) were dissolved in 10 ml of 50percent aqueous ETOH. While stirring, a solution of 243 mg (2.43 mmol) of potassium bicarbonate in 5 ml of water was added dropwise over 1 h. The resulting solution was stirred for an additional 4 h, diluted with 25 ml of water, and extracted with CHLOROFORM (3 x 25 ml). The combined organic extract was dried over sodium sulfate and concentrated in vacuo to a colourless oil, 345 mg (78percent yield) as a 7: 1 mixture of the 5-and 4- carboxylates. H NMR (CDC11. 34 (t, 3H, J = 7.16Hz), 4.30 4.37 (2q, 2H, J = 7.16 Hz), 6.92 8.81 (2s, IH, ratio 7: 1).EXAMPLE 5 3-bromo-5-carboxyisoxazole A solution of 442 mg (2.0 mmol) of ethyl 3-BROMOISOXAZOLE-5-CARBOXYLATE (Intermediate 119) and 5.0 ml of I N sodium hydroxide in 10 ml OF MEOH was stirred at ambient temperature for 5 h, then acidified with 6.0 ml of 1 N hydrochloric acid, diluted with 25 ml of water and extracted with EtOAc (3 x 25 ML). The combined organic extract was dried over magnesium sulfate and concentrated in vacuo to give the title compound as a white solid (310 mg). MS. 0. 30 (ES-) 189. 99/191.99/193. 17; C4H2BrNO3 191. 97 'H NMR 8 : 7.46 (s, 1 H)

Molecular Weight:220.02
XLogP3:1.9
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:3
Exact Mass:218.95311
Monoisotopic Mass:218.95311
Topological Polar Surface Area:52.3
Heavy Atom Count:11
Complexity:153
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes