L. Bianchi et al. / Tetrahedron 58 +2002) 3379±3385
3383
the reaction to completion within an overall 4±5 h time.
Usual workup involved pouring the reaction mixture into
water and extraction with Et2O, followed by washing of the
combined extracts with brine. After drying -Na2SO4) the
organic layer and solvent removal under reduced pressure,
the residue was chromatographed on a silica gel column
-CH2Cl2 as eluant) to furnish the oximes 4 as single con-
®gurational isomers -1H and 13C NMR) in the yields
reported in Table 2. In some instances the hydroximino
protons were not clearly detectable in the 1H NMR spectra.
-light petroleum); nmax 3270, 1626, 1544, 1486, 1429, 1415,
1298, 1244, 1159, 1105, 1089, 1007 cm21; 1H NMR: d 2.27
-3H, s), 2.37 -3H, s), 3.90-2H, s), 5.74 -1H, s), 7.16 and 7.26
-2H each, AA0BB0, J8.6 Hz), ca. 8.1 -1H, br s); 13C NMR:
d 16.47, 17.25, 33.72, 117.67, 128.59, 130.32, 132.19,
135.30, 142.93, 155.38. Anal. Calcd for C12H14ClNOS2: C,
50.1; H, 4.9; N, 4.9%. Found: C, 50.2; H, 4.9; N, 5.0%.
4.3.7. 3-Hydroximino-1,1-bisꢀmethylthio)-4-ꢀ1-naphthyl)-
1-butene ꢀ4g). White solid, mp 113.6±114.98C -light petro-
1
leum); nmax 3266, 1597, 1519, 1422, 1245, 1016 cm21; H
4.3.1.
3-Hydroximino-1,1-bisꢀmethylthio)-4-phenyl-1-
NMR: d 1.94 -3H, s), 2.31 -3H, s), 4.36 -2H, s), 5.53 -1H, s),
7.33 -1H, br d, J5.9 Hz), 7.50-3H, m), 7.76 -1H, br d,
J7.7 Hz), 7.85 -1H, m), 8.01 -1H, m); 13C NMR: d 16.31,
16.87, 31.99, 116.87, 124.02, 125.50, 125.77, 126.22,
127.10, 127.43, 128.61, 132.30, 132.94, 133.72, 142.29,
155.45. Anal. Calcd for C16H17NOS2: C, 63.3; H, 5.6; N,
4.6%. Found: C, 63.4; H, 5.7; N, 4.7%.
butene ꢀ4a). Pale-yellow solid, mp 58.4±58.98C -petroleum
ether/CH2Cl2); nmax 3264, 1619, 1598, 1526, 1491, 1434,
1332, 1299, 1244, 1016 cm21; 1H NMR: d 2.23 -3H, s), 2.35
-3H, s), 3.93 -2H, s), 5.74 -1H, s), 7.24 -5H, m); 13C NMR: d
16.45, 17.23, 34.38, 117.91, 126.39, 128.52, 129.05, 136.82,
142.40, 155.91. Anal. Calcd for C12H15NOS2: C, 56.9; H,
6.0; N, 5.5%. Found: C, 57.0; H, 6.0; N, 5.4%.
4.3.8. 3-Hydroximino-1,1-bisꢀmethylthio)-4-ꢀ2-naphthyl)-
1-butene ꢀ4h). Pale-yellow solid, mp 98.5±99.08C -light
petroleum); nmax 3264, 1611, 1599, 1529, 1425, 1244,
4.3.2. 3-Hydroximino-4-ꢀ4-methylphenyl)-1,1-bisꢀmethyl-
thio)-1-butene ꢀ4b). Pale-yellow solid, mp 51.6±52.88C
-taken up with petroleum ether); nmax 3293, 1669, 1608,
1
1016 cm21; H NMR: d 2.20-3H, s), 2.35 -3H, s), 4.10
1
1546, 1512, 1428, 1322, 1296, 1240, 1227, 1014 cm21; H
-2H, s), 5.81 -1H, s), 7.42 -3H, m), 7.66 -1H, s), 7.79 -3H,
m); 13C NMR: d 16.49, 17.25, 34.51, 118.07, 125.46,
126.01, 127.30, 127.56, 127.61, 128.10, 132.18, 133.58,
134.34, 142.55, 155.75. Anal. Calcd for C16H17NOS2: C,
63.3; H, 5.6; N, 4.6%. Found: C, 63.5; H, 5.7; N, 4.7%.
NMR: d 2.24 -3H, s), 2.31 -3H, s), 2.36 -3H, s), 3.89 -2H, s),
5.76, -1H, s), 7.19, -4H, app s); 13C NMR: d 16.48, 17.23,
21.03, 33.96, 118.31, 128.89, 129.16, 133.65, 135.85,
142.12, 155.88. Anal. Calcd for C13H17NOS2: C, 58.4; H,
6.4; N, 5.2%. Found: C, 58.4; H, 6.5; N, 5.3%.
4.3.9. 3-Hydroximino-1,1-bisꢀmethylthio)-4-ꢀ2-thienyl)-
1-butene ꢀ4i). Pale-yellow solid, mp 60.2±61.28C -petro-
leum ether/CH2Cl2); nmax 3255, 1608, 1530, 1421, 1332,
4.3.3. 3-Hydroximino-4-ꢀ3-methoxyphenyl)-1,1-bis-
ꢀmethylthio)-1-butene ꢀ4c). Yellow oil; nmax 3301, 2994,
2919, 2832, 1595, 1584, 1530, 1487, 1429, 1316, 1258,
1290, 1257, 1228, 1134, 1010 cm21 1H NMR: d 2.28
;
1
1148, 1047, 1011 cm21; H NMR: d 2.24 -3H, s), 2.37
-3H, s), 2.39 -3H, s), 4.12 -2H, s), 5.81 -1H, s), 6.90-2H,
m), 7.15 -1H, dd, J1.4 and 5.3 Hz), ca. 8.5 -1H, br s); 13C
NMR: d 16.52, 17.21, 28.62, 117.18, 124.26, 126.24,
126.81, 138.51, 142.93, 154.81. Anal. Calcd for
C10H13NOS3: C, 46.3; H, 5.1; N, 5.4%. Found: C, 46.5; H,
5.1; N, 5.5%.
-3H, s), 3.79 -3H, s), 3.91 -2H, s), 5.76 -1H, s), 6.78 -3H,
m), 7.20-1H, dt, J1.0and 7.5 Hz), ca. 8.40-1H, br s); 13C
NMR: d 16.42, 17.11, 34.35, 55.09, 111.76, 114.66, 118.28,
121.41, 129.31, 138.28, 142.12, 155.15, 159.62. Anal. Calcd
for C13H17NO2S2: C, 55.1; H, 6.0; N, 4.9%. Found: C, 55.2;
H, 6.2; N, 5.0%.
4.4. Cyclization of compounds 4a±i to the isoxazoles 5a±i
4.3.4. 3-Hydroximino-4-ꢀ4-methoxyphenyl)-1,1-bis-
ꢀmethylthio)-1-butene ꢀ4d). Pale-yellow oil; nmax 3302,
2994, 2919, 2833, 1610, 1584, 1509, 1463, 1432, 1300,
The acidic ion-exchange resin -Amberlyst-15w, special for
non-aqueous systems, 0.1 g) was added to a solution of 4
-0.1 g) in dry acetonitrile -5.5 ml) and the mixture was
heated to re¯ux under stirring. The progress of the reaction
-generally complete in 15 min) was monitored by TLC
-petroleum ether/Et2O mixtures as eluants). The resin was
®ltered off and washed three times by stirring for 30min in
anhydrous Et2O. The combined ethereal washings were
reunited to the acetonitrile solution. After solvent evapo-
ration under reduced pressure, chromatography on silica
gel -petroleum ether/Et2O mixtures as eluant) allowed to
isolate pure isoxazoles 5 in the yields reported in Table 3.
1
1248, 1177, 1105, 1035 cm21; H NMR: d 2.24 -3H, s),
2.36 -3H, s), 3.78 -3H, s), 3.87 -2H, s), 5.76 -1H, s), 6.83
and 7.14 -2H each, AA0BB0, J8.7 Hz); 13C NMR: d 16.47,
17.24, 33.47, 55.23, 113.91, 118.21, 128.79, 130.02, 142.15,
156.05, 158.16. Anal. Calcd for C13H17NO2S2: C, 55.1; H,
6.0; N, 4.9%. Found: C, 55.2; H, 6.1; N, 5.0%.
4.3.5. 4-ꢀ3-Chlorophenyl)-3-hydroximino-1,1-bisꢀmethyl-
thio)-1-butene ꢀ4e). Pale-yellow solid, mp 65.4±66.88C
-petroleum ether/CH2Cl2); nmax 3255, 1595, 1566, 1525,
1
1433, 1243, 1078, 1020 cm21; H NMR: d 2.27 -3H, s),
2.37 -3H, s), 3.92 -2H, s), 5.76 -1H, s), 7.16 -4H, m); 13C
NMR: d 16.58, 17.30, 34.07, 117.87, 126.66, 127.21,
129.15, 129.74, 134.28, 138.89, 143.06, 155.09. Anal.
Calcd for C12H14ClNOS2: C, 50.2; H, 4.9; N, 4.9%.
Found: C, 50.3; H, 5.0; N, 4.9%.
4.4.1. 3-Benzyl-5-ꢀmethylthio)isoxazole ꢀ5a). Low-melt-
ing pale-yellow solid; nmax 3144, 1601, 1547, 1494, 1446,
1413, 1404, 1320, 1210, 1091, 1073, 1031 cm21; 1H NMR:
d 2.52 -3H, s), 3.96 -2H, s), 5.82 -1H, s), 7.30-5H, m); 13C
NMR: d 15.21, 32.37, 101.69, 126.85, 128.69, 128.75,
136.97, 163.62, 167.55. Anal. Calcd for C11H11NOS: C,
64.4; H, 5.4; N, 6.8%. Found: C, 64.6; H, 5.5; N, 6.7%.
4.3.6. 4-ꢀ4-Chlorophenyl)-3-hydroximino-1,1-bisꢀmethyl-
thio)-1-butene ꢀ4f). Pale-yellow solid, mp 106.0±106.38C