9856
A. Guirado et al. / Tetrahedron 58 (2002) 9853–9858
in the cathodic and the anodic compartments. Anhydrous
sodium carbonate (3 g) was placed in the anode compart-
ment to prevent accumulation of electrogenerated acid.
Solutions of compounds 4 (5 mmol) were electrolysed
under the following cathodic potentials: 22.10 V vs SCE
(entries m, o); 22.05 V vs SCE (entries a–f); 22.00 V vs
SCE (entries n, r); 21.90 V (entries g–i, k, l, p, q). The
average current intensity was 200 mA at the beginning, and
15 mA at the end. The cell voltage values remained below
8 V in all cases. All electrolysis products were isolated by
removing the solvent in vacuo. The residue was then shaken
with ether (3£50 mL) over a period of 30 min. The ethereal
solutions were combined and concentrated leaving oily
crude products in high purity state,19 which were purified by
column chromatography on silica gel (ethyl acetate or ethyl
acetate–hexane 1:1). The isolated products were viscous
yellow oils that gave satisfactory elemental and spectro-
scopic analyses.
(CDCl3, 200 MHz): 1.12 (d, 6H, J¼6.3 Hz), 1.86 (br s, 1H),
3.36 (sept, 1H, J¼6.3 Hz), 3.97 (dd, 1H, J¼9.3, 6.9 Hz),
4.52 (t, 1H, J¼9.1 Hz), 5.22 (t, 1H, J¼8.7 Hz), 7.36–7.52
(m, 3H), 7.96 (dd, 2H, J¼8.8, 1.7 Hz); 13C NMR d (CDCl3,
75.4 MHz): 22.43 (CH3), 24.39 (CH3), 45.45 (CH), 73.17
(CH2), 79.33 (CH), 127.90 (CH), 128.30 (CH), 128.35
(CH), 131.46 (C), 164.26 (CvN); FABþ: 205 (Mþþ1,
100); IR (film): 3295, 1648, 1578, 1448, 1350, 1174, 1086,
1026, 987, 948, 698 cm21
.
3.2.5. 4-Dietilamino-2-phenyl-2-oxazoline (7e). (73%),
pale yellow oil. (Found: C 71.71; H 8.34; N 12.80;
1
C13H18N2O requires: C 71.53; H 8.31; N 12.83); H NMR
d (CDCl3, 300 MHz): 1.13 (t, 6H, J¼7.2 Hz), 2.64 (c, 4H,
J¼7.2 Hz), 4.19 (dd, 1H, J¼9.5, 5.7 Hz), 4.36 (t, 1H,
J¼9.5 Hz), 5.35 (dd, 1H, J¼9.5, 5.7 Hz), 7.37–7.47 (m,
3H), 7.97 (dd, 2H, J¼8.2, 1.5 Hz); 13C NMR d (CDCl3,
75.4 MHz): 13.83 (CH3), 42.86 (CH2), 70.17 (CH2), 84.08
(CH), 127.76 (CH), 128.28 (CH), 128.40 (CH), 131.39 (C),
164.21 (CvN); MS, m/z (%): 218 (Mþ, 11), 217 (23), 146
(69), 145 (100), 117 (60), 105 (37), 90 (76), 89 (39), 77 (39),
58 (76), 57 (40); IR (film): 3327, 2975, 1648, 1525, 1456,
3.2.1. 4-Benzylamino-2-phenyl-2-oxazoline (7a). (72%),
pale yellow oil. (Found: C 75.98; H 6.44; N 11.14;
1
C16H16N2O requires C 76.16; H 6.39; N 11.10); H NMR
d (CDCl3, 300 MHz): 2.79 (br s, 1H), 3.91 (d, 1H,
J¼13.2 Hz), 4.03–4.08 (m, 2H), 4.45 (t, 1H, J¼9.0 Hz),
5.22 (dd, 1H, J¼8.7, 6.6 Hz), 7.22–7.47 (m, 8H), 7.98 (dd,
2H, J¼8.4, 1.5 Hz); 13C NMR d (CDCl3, 75.4 MHz): 49.19
(CH2), 71.93 (CH2), 80.85 (CH), 126.89 (CH), 127.60 (CH),
128.14 (CH), 128.24 (CH), 128.28 (CH), 128.31 (CH),
131.47 (C), 139.90 (C), 164.56 (CvN); MS, m/z (%): 251
(Mþ2H, 28), 131 (72), 118 (44), 104 (63), 91 (100), 77
(31); FABþ: 253 (Mþ1, 100); IR (film): 3268, 1643, 1452,
1386, 1349, 1306, 1216, 1070, 967 cm21
.
3.2.6. 4-Cyclohexylamino-2-phenyl-2-oxazoline (7f).
(60%), pale yellow oil. (Found: C 73.63; H 8.19; N 11.43;
C15H20N2O requires: C 73.74; H 8.25; N 11.46); 1H NMR d
(CDCl3, 200 MHz): 0.91–2.35 (m, 12H), 3.96 (dd, 1H,
J¼9.2, 6.9 Hz), 4.51 (t, 1H, J¼9.1 Hz), 5.25 (dd, 1H, J¼8.6,
6.9 Hz), 7.31–7.48 (m, 3H), 7.96 (dd, 2H, J¼8.2, 1.8 Hz);
13C NMR d (CDCl3, 50.4 MHz): 24.79 (CH2), 25.10 (CH2),
26.09 (CH2), 33.29 (CH2), 34.87 (CH2), 53.39 (CH), 73.23
(CH2), 78.91 (CH), 127.92 (CH), 128.31 (CH), 128.37
(CH), 131.47 (C), 164.29 (CvN); MS, m/z (%): 244 (Mþ,
6), 243 (19), 146 (100), 123 (55), 91 (44), 77 (47), 56 (53);
IR (film): 3251, 1645, 1455, 1377, 1354, 1246, 1160, 1092,
1372, 1249, 1139, 1088, 1025, 956, 744, 694 cm21
.
3.2.2. 2-Phenyl-4-methylamino-2-oxazoline (7b). (92%),
pale yellow oil. (Found: C 68.38; H 6.91; N 15.96;
1
C10H12N2O requires: C 68.16; H 6.86; N 15.90); H NMR
d (DMSO-d6, 300 MHz): 2.36 (br s, 4H), 3.96 (dd, 1H,
J¼9.0, 7.2 Hz), 4.43 (t, 1H, J¼9.3 Hz), 5.03 (dd, 1H, J¼9.3,
7.2 Hz), 7.43–7.57 (m, 3H), 7.92 (dd, 2H, J¼8.8, 1.8 Hz);
13C NMR d (DMSO-d6, 75.4 MHz): 31.04 (CH3), 70.96
(CH2), 82.25 (CH), 127.80 (CH), 127.88 (CH), 128.52
(CH), 131.45 (C), 162.45 (CvN); MS, m/z (%): 176 (Mþ,
66), 175 (100), 146 (78), 105 (72), 104 (88), 91 (57), 77
(86); IR (film): 3287, 2949, 1647, 1578, 1451, 1355, 1310,
1026, 956, 696 cm21
.
3.2.7. 4-Benzylamino-2-(3-chlorophenyl)-2-oxazoline
(7h). (58%), pale yellow oil. (Found: C 66.95; H 5.22; N
1
9.69; C16H15ClN2O requires: C 67.02; H 5.27; N 9.77); H
NMR d (CDCl3, 200 MHz): 1.95 (br s, 1H), 3.89–4.13 (m,
3H), 4.49 (t, 1H, J¼9.3 Hz), 5.23 (dd, 1H, J¼8.8, 6.8 Hz),
7.24–7.49 (m, 7H), 7.86 (dt, 1H, J¼7.7, 1.4 Hz), 7.98 (t,
1H, J¼1.8 Hz); 13C NMR d (CDCl3, 50.4 MHz): 49.51
(CH2), 72.33 (CH2), 81.16 (CH), 126.54 (CH), 127.12 (CH),
128.31 (CH), 128.48 (CH), 128.57 (CH), 129.60 (C), 129.72
(CH), 131.63 (CH), 134.50 (C), 139.98 (C), 163.46 (CvN);
MS, m/z (%): 286 (Mþ, 1), 195 (3), 180 (5), 152 (5), 138
(19), 131 (65), 118 (28), 104 (31), 91 (100), 75 (15); IR
(film): 3282, 3066, 3029, 2900, 1737, 1647, 1574, 1470,
1246, 1140, 1085, 1067, 1027, 960, 698 cm21
.
3.2.3. 2-Phenyl-4-propylamino-2-oxazoline (7c). (65%),
pale yellow oil. (Found: C 70.71; H 7.87; N 13.68;
1
C12H16N2O requires: C 70.56; H 7.90; N 13.71); H NMR
d (CDCl3, 200 MHz): 0.93 (t, 3H, J¼7.4 Hz), 1.43–1.58 (m,
3H), 2.58–2.71 (m, 1H), 2.79–2.92 (m, 1H), 4.04 (dd, 1H,
J¼9.2, 6.6 Hz), 4.47 (t, 1H, J¼9.2 Hz), 5.18 (dd, 1H, J¼8.9,
6.6 Hz), 7.29–7.48 (m, 3H), 7.97 (dd, 2H, J¼7.0, 1.5 Hz);
13C NMR d (CDCl3, 50.4 MHz): 11.80 (CH3), 23.57 (CH2),
46.89 (CH2), 71.96 (CH2), 81.34 (CH), 127.72 (CH), 128.32
(CH), 128.46 (CH), 131.49 (C), 164.36 (CvN); MS, m/z
(%): 204 (Mþ, 50), 203 (75), 146 (100), 118 (53), 105 (89),
91 (92), 77 (88); IR (film): 3289, 2961, 1649, 1579, 1450,
1355, 1246, 1145, 1119, 1079, 969 cm21
.
3.2.8. 4-Benzylamino-2-(3,4,5-trimethoxyphenyl)-2-oxa-
zoline (7m). (55%), pale yellow powder; mp 100–1038C.
(Found: C 66.55; H 6.50; N 8.23; C19H22N2O4 requires: C
66.65; H 6.48; N 8.18); 1H NMR d (CDCl3, 200 MHz): 1.91
(s, 1H), 3.89 (s, 3H), 3.92 (s, 6H), 3.95–4.05 (m, 2H), 4.10
(dd, 1H, J¼6.2, 3.5 Hz), 4.49 (t, 1H, J¼8.9 Hz), 5.25 (dd,
1H, J¼8.8, 6.5 Hz), 7.23 (s, 2H), 7.26–7.41 (m, 5H); 13C
NMR d (CDCl3, 50.4 MHz): 49.34 (CH2), 56.27 (CH3O),
60.97 (CH3O), 72.22 (CH2), 81.18 (CH), 105.60 (CH),
122.93 (C), 127.07 (CH), 128.25 (CH), 128.46 (CH), 140.11
1355, 1242, 1136, 1086, 1025, 965, 698 cm21
.
3.2.4. 4-Isopropylamino-2-phenyl-2-oxazoline (7d).
(68%), pale yellow oil. (Found: C 70.48; H 7.95; N 13.67;
C12H16N2O requires: C 70.56; H 7.90; N 13.71); 1H NMR d