RESEARCH ARTICLE
(5 mol%) were taken in a zirconia grinding jar (45 mL). To this
mixture was added six zirconia balls (d=15 mm) and ball-
milled for 1 h at 400 rpm. After completion of the reaction as
indicated by TLC, 10 mL of ethyl acetate was added in portions
to the residue and centrifuged to remove CuONP. The filtered
organic solution was evaporated under reduced pressure and the
resulting crude product was purified by silica gel (100–
200 mesh) column chromatography using hexane/EtOAc to
obtain the purified product 3.
Ethyl 5-(4-(pentyloxy)phenyl)isoxazole-
3-carboxylate (3f)[43]
°
White solid; Yield: 258 mg (85%); mp:70–72 C; FT-IR (neat):
υ=1726, 1625, 1253 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.64 (d, J=8.5 Hz, 2H), 6.89 (d, J=8.5 Hz, 2H), 6.70 (s,
1H), 4.38 (q, J=7.0 Hz, 2H), 3.92 (t, J=6.5 Hz, 2H), 1.75-1.69
(m, 2H), 1.40-1.30 (m, 7H), 0.86 (t, J=7.0 Hz, 3H); 13C NMR
(125 MHz, CDCl3): δ (ppm) 171.8, 161.2, 160.2, 156.9, 127.5,
119.2, 115.0, 98.4, 68.2, 62.1, 28.8, 28.1, 22.4, 14.2, 13.9.
Ethyl 5-phenylisoxazole-3-carboxylate°(3a)[19b]
Ethyl 5-hexylisoxazole-3-carboxylate (3g)[12g]
White solid; Yield: 178 mg (82%); mp: 47–49 C; FT-IR (neat):
υ=1726, 1613, 1256 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.83-7.81 (m, 2H), 7.50-7.49 (m, 3H), 6.94 (s, 1H), 4.49
(q, J=7.0 Hz, 2H), 1.46 (t, J=7.0 Hz, 3H); 13C NMR
(125 MHz, CDCl3): δ (ppm) 171.7, 160.0, 156.9, 130.8, 129.2,
126.6, 125.9, 99.9, 62.2, 14.2.
Clear oil; Yield: 189 mg (84%); FT-IR (neat): υ=1716, 1597,
1
1223 cmÀ 1; H NMR (500 MHz, CDCl3): δ (ppm) 6.33 (s, 1H),
4.36 (q, J=7.5 Hz, 2H), 2.72 (t, J=7.5 Hz, 2H), 1.66 (q, J=
7.0 Hz, 2H), 1.34 (t, J=7.5 Hz, 3H), 1.30–1.28 (m, 2H), 1.25–
1.22 (m, 4H), 0.82-0.80 (m, 3H); 13C NMR(125 MHz, CDCl3):
δ (ppm) 175.7, 160.3, 156.3, 101.4, 62.0, 31.3, 28.6, 27.3, 26.7,
22.4, 14.1, 13.9.
Ethyl 5-(4-bromophenyl)isoxazole-3-carboxylate
(3b)[12g]
Methyl 5-phenylisoxazole-3-carboxylate (3h)[44]
°
White solid; Yield:213 mg(72%); mp:82–84 C; FT-IR (neat):
°
υ=1732, 1618, 1266 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.61 (d, J=8.5 Hz, 2H), 7.57 (d, J=8.5 Hz, 2H), 6.86 (s,
1H), 4.41 (q, J=7.0 Hz, 2H), 1.37 (t, J=7.0 Hz, 3H); 13C NMR
(125 MHz, CDCl3): δ (ppm) 170.6, 159.9, 157.1, 132.5, 127.4,
125.5, 125.3, 100.3, 62.3, 14.2.
White solid; Yield: 173 mg(85%); mp65–67 C; FT-IR (neat):
υ=1722, 1648, 1235 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.74–7.72 (m, 2H), 7.41–7.40 (m, 3H), 6.86 (s, 1H), 3.93
(s, 3H); 13C NMR (125 MHz, CDCl3): δ (ppm) 171.8, 160.5,
156.7, 130.9, 129.2, 126.6, 125.9, 99.9, 52.9.
Methyl 5-(p-tolyl)isoxazole-3-carboxylate (3i)[44]
Ethyl 5-(4-fluorophenyl)isoxazole-3-carboxylate
(3c)[12c]
°
White solid; Yield: 193 mg(89%); mp128–130 C; FT-IR (neat):
υ=1728, 1642, 1226 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.70 (d, J=8.0 Hz, 2H), 7.29 (d, J=8.5 Hz, 2H), 6.88 (s,
1H), 4.01 (s, 3H), 2.42 (s, 3H); 13C NMR (125 MHz, CDCl3): δ
(ppm) 172.0, 160.5, 156.6, 141.3, 129.8, 125.9, 123.9, 99.3,
52.9, 21.5.
°
White solid; Yield: 176 mg(75%); mp:68–70 C; FT-IR (neat):
υ=1728, 1619, 1263 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.83-7.80 (m, 2H), 7.20 (t, J=8.5 Hz, 2H), 6.89 (s, 1H),
4.48 (q, J=7.0 Hz, 2H), 1.45 (t, J=7.0 Hz, 3H); 13C NMR
(125 MHz, CDCl3): δ (ppm) 170.7, 164.1 (d, J=250.8 Hz),
159.9, 157.0, 128.1 (d, J=8.6 Hz), 123.0 (d, J=3.4 Hz), 116.4
(d, J=22.1 Hz), 99.7, 62.3, 14.2.
Methyl 5-(m-tolyl)isoxazole-3-carboxylate (3j)[28b]
°
White solid; Yield: 189 mg(87%);mp:118–121 C; FT-IR (neat):
Ethyl 5-(p–tolyl)isoxazole-3-carboxylate (3d)[12c]
υ=1726, 1642, 1224 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.54–7.51 (m, 2H), 7.29 (t, J=7.5 Hz, 1H), 7.21–7.19
(m, 1H), 6.83 (s, 1H), 3.92 (s, 3H), 2.34 (s, 3H); 13C NMR
(125 MHz, CDCl3): δ (ppm) 172.0, 160.5, 156.6, 139.0, 131.7,
129.1, 126.5, 123.1, 99.8, 52.9, 21.4.
°
White solid; Yield: 213 mg (92%); mp:58–60 C; FT-IR (neat):
υ=1725, 1615, 1263 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.71 (d, J=8.0 Hz, 2H), 7.29 (d, J=8.5 Hz, 2H), 6.88 (s,
1H), 4.48 (q, J=7.0 Hz, 2H), 2.42 (s, 3H), 1.45 (t, J=7.5 Hz,
3H); 13C NMR(125 MHz, CDCl3): δ (ppm) 171.9, 160.1, 156.9,
141.2, 129.8, 125.9, 123.9, 99.3, 62.2, 21.5, 14.2.
Methyl 5-(hydroxymethyl)isoxazole-3-carboxylate
(3k)[45]
Ethyl 5-(m–tolyl)isoxazole-3-carboxylate (3e)[42]
Colourless oil; Yield: 107 mg (68%); FT-IR (neat): υ=3341,
1726, 1642, 1224 cmÀ 1; H NMR (500 MHz, CDCl3): δ (ppm)
1
°
White solid; Yield: 206 mg (89%); mp:55–57 C; FT-IR (neat):
6.67 (s, 1H), 4.82 (s, 2H), 3.97 (s, 3H), 3.57 (brs, 1H); 13C
NMR (125 MHz, CDCl3): δ (ppm) 173.8, 160.3, 155.9, 102.5,
56.1, 53.0.
υ=1746, 1619, 1263 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
(ppm) 7.65-7.62 (m, 2H), 7.40 (t, J=7.5 Hz, 1H), 7.31 (d, J=
7.5 Hz, 1H), 6.93 (s, 1H), 4.50 (q, J=7.5 Hz, 2H), 2.45 (s, 3H),
1.47 (t, J=7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ (ppm)
171.9, 160.1, 156.9, 139.0, 131.6, 129.1, 126.6, 126.5, 123.1,
99.8, 62.2, 21.4, 14.2.
Phenyl (5-phenylisoxazol-3-yl)methanone (3l)[43]
°
White solid; Yield: 219 mg (88%); mp:78–80 C; FT-IR (neat):
υ=1665, 1628, 1223 cmÀ 1; 1H NMR (500 MHz, CDCl3): δ
Adv. Synth. Catal. 2021, 363, 1–13
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