8
552
I. Fejes et al. / Tetrahedron 56 (2000) 8545±8553
Oxidations with MnO2
Ethyl 3-(4-chlorophenyl)-5-phenyl-pyrroline-2-carboxyl-
ate (15h). White powder; yield 83%; mp 108±110 8C;
[Found; C, 69.4; H, 5.6; N, 4.2. C19 requires C,
69.62; H, 5.53; N, 4.27%]; d (CDCl , 250 MHz): 7.38±
General procedure: The appropriate cycloadduct (1 mmol)
was dissolved in THF (10 mL) and manganese(IV)-oxide
H18ClNO
2
H
3
(
0.87 g, 10 mmol) was added. The reaction mixture was
7.32 (5H, m, Ph-H), 7.27±7.20 (2H, m, Ar-H), 7.08 (2H, d,
J8.2 Hz, Ar-H), 6.01 (1H, d, J7.5 Hz, H-4), 5.34 (1H,
dd, J7.5 and 2.6 Hz, H-5), 5.26 (1H, s, H-2), 4.31 (2H, q,
); d
3 C
stirred under the conditions given in Table 2. After the
completion of the reaction (judged by TLC) all the solid
was removed by ®ltration and the residue was evaporated.
The product ratios (see Table 2) were determined from the
crude reaction mixture, while the pure compounds were
obtained by column chromatography.
J7.1 Hz, CH
(63 MHz, CDCl
CH
), 1.29 (3H, t, J7.1 Hz, CH
): 167.9 (q), 160.7 (q), 134.7 (q), 133.1
2
3
3
(q), 133.0 (q), 129.8 (2£CH), 129.0 (CH), 128.8 (2£CH),
128.6 (2£CH), 127.4 (2£CH), 94.7 (CH), 79.4 (CH), 62.7
(
327 (M , 37), 325 (100), 279 (63), 253 (20), 216 (82), 189
CH ), 59.9 (CH), 14.0 (CH ); EIMS m/z (rel. intensity, %):
2 3
1
Ethyl 3,5-diphenyl-pyrroline-2-carboxylate (15b). White
powder; yield 87%; mp 105±1078C; [Found: C, 77.9; H,
6
4
7
2
1
(23), 117 (21), 105 (28); IR (nujol, cm ): 3315, 3062, 3025,
2985, 2960, 2902, 1743, 1652, 1554, 1490, 1450, 1367,
1301, 1259, 1197, 1126, 1087, 1014, 917, 852, 806, 754,
707, 607, 538.
.7; N, 4.7. C H NO requires C, 77.79; H, 6.53; N,
19 19 2
.77%]; dH (CDCl , 250 MHz): 7.40±7.29 (6H, m, Ph),
3
.29±7.22 (2H, m, Ph), 7.19±7.13 (2H, m, Ph), 6.02 (1H,
d, J7.3 Hz, H-4), 5.37 (1H, dd, J7.3 and 2.2 Hz, H-5),
.27 (1H, s, H-2), 4.29 (2H, dq, J7.1 and 1.4 Hz,
CH CH ), 1.27 (3H, t, J7.1 Hz, CH CH ); d (63 MHz,
5
Ethyl 3,5-diphenyl-1H-pyrrole-2-carboxylate (16b). Pale
yellow powder; yield 60%; mp 138±1398C; [Found: C,
2
3
2
3
C
CDCl ): 168.4 (q), 160.8 (q), 134.6 (q), 133.2 (q), 129.7
78.8; H, 5.7; N, 4.8. C19 requires C, 78.33; H,
5.88; N, 4.81%]; d (CDCl , 250 MHz): 9.80 (1H, br s,
3
H17NO
2
3
(
(
(
2£CH), 128.9 (CH), 128.7 (CH), 128.5 (2£CH), 127.4
2£CH), 127.3 (2£CH), 95.0 (CH), 79.4 (CH), 62.5
CH ), 60.7 (CH), 13.9 (CH ); EIMS m/z (rel. intensity,
H
NH), 7.70±7.60 (4H, m, Ph-H), 7.48±7.28 (6H, m, Ph-H),
6.60 (1H, d, J3.0 Hz, H-4), 4.23 (2H, q, J7.1 Hz,
2
3
1
%): 292 (M -1, 100), 274 (5), 246 (19), 220 (7), 118
3), 106 (4), 85 (10), 71 (7); IR (KBr, cm ): 3417,
CH ), 1.20 (3H, t, J7.1 Hz, CH
CDCl ): 161.5 (q), 135.6 (q), 135.2 (q), 133.4 (q), 131.1 (q),
3
CH
2
3
CH ); d (63 MHz,
2 3 C
2
1
(
2
1
987, 1720, 1635, 1545, 1493, 1545, 1454, 1374, 1261,
107, 995.
129.6 (2£CH), 128.9 (2£CH), 127.8 (CH), 127.6 (2£CH),
127.0 (CH), 124.9 (2£CH), 118.7 (q), 110.0 (CH), 60.5
1
CH ), 14.1 (CH ); EIMS m/z (rel. intensity, %): 291 (M ,
(
100), 275 (5), 245 (71), 217 (69), 189 (25), 175 (6), 140 (6),
2
3
Ethyl 3-(4-methoxyphenyl)-5-phenyl-pyrroline-2-carboxyl-
ate (15c). White powder; yield 76%; mp 117±1198C;
2
1
115 (6), 89 (7), 77 (5); IR (KBr, cm ): 3411, 3313, 2975,
1660, 1601, 1459, 1433, 1290, 1263, 1203, 1132, 1022.
[
Found: C, 74.6; H, 6.7; N, 4.3. C H NO requires C,
20 21 3
74.28; H, 6.55; N, 4.33%]; dH (CDCl , 250 MHz): 7.40±
3
7
.30 (3H, m, Ph), 7.30±7.20 (2H, m, Ph), 7.07 (2H, d,
Ethyl 3-(4-methoxyphenyl)-5-phenyl-1H-pyrrole-2-car-
boxylate (16c). Pale yellow powder; yield 21%; mp 132±
1338C; (lit. 1358C); d (CDCl , 250 MHz): 9.47 (1H, s,
H 3
J8.3 Hz, Ar), 6.90 (2H, d, J8.3 Hz, Ar), 6.00 (1H, d,
J7 Hz, H-4), 5.34 (1H, d, J7.0 Hz, H-5), 5.22 (1H, s,
H-2), 4.30 (2H, q, J7.1 Hz, CH CH ), 3.78 (3H, s,
1
3
NH), 7.61 (2H, d, J7.5 Hz, Ph-H), 7.52 (2H, d, J8.2 Hz,
Ar-H), 7.38 (2H, t, J7.5 Hz, Ph-H), 7.29 (1H, d, 7.5 Hz,
Ph-H), 6.42 (2H, d, J8.2 Hz, Ar-H), 6.57 (1H, d,
2
3
OCH ), 1.28 (t, 3H, CH ); d (63 MHz, CDCl ): 168.7
3
3
C
3
(
(
q), 160.9 (q), 159.8 (q), 133.4 (q), 128.8 (CH), 128.6
2£CH), 128.5 (2£CH), 127.4 (2£CH), 126.3 (CH), 115.0
1
CH ), 14.0 (CH ); EIMS m/z (rel. intensity, %): 322 (M -1,
J1.9 Hz, H-4), 4.20 (2H, q, J7.0 Hz, CH CH
CH ); d (63 MHz, CDCl ): 161.5
2 3 C 3
), 1.21
2
3
(
(
2£CH), 95.1 (CH), 79.3 (CH), 62.5 (CH ), 60.1 (CH), 55.3
(3H, t, J7.0 Hz, CH
2
(q), 158.8 (q), 135.6 (q) 133.3 (q), 131.2 (q), 130.7
(2£CH), 128.9 (2£CH), 127.8 (CH), 127.6 (q), 124.9
(2£CH), 118.4 (q), 113.1 (2£CH), 109.8 (CH), 60.4
(CH ), 55.2 (CH ), 14.2 (CH ); EIMS m/z (rel. intensity,
2 3 3
3
3
2
1
100), 304 (11), 276 (74), 250 (14), 57 (38); IR (nujol, cm ):
1722, 1627, 1602, 1581, 1512, 1302, 1250, 1165, 1112,
1029.
1
%
): 321 (M , 100), 275 (60), 247 (22), 232 (30), 204
2
1
Ethyl 3-(3,4-methylenedioxyphenyl)-5-phenyl-pyrroline-
2-carboxylate (15g). White powder; yield 63%; mp 120±
1228C; [Found: C, 71.3; H, 6.0; N, 4.2. C H NO requires
C, 71.20; H, 5.68; N, 4.15%]; d (CDCl , 250 MHz): 7.32
(19), 176 (8), 137 (6), 102 (5); IR (KBr, cm ): 3440,
3310, 2934, 1675, 1527, 1452, 1191, 1171, 1248, 1178,
1029, 812, 774;
2
0
19
4
H
3
(
6
3H, m, Ph), 7.23 (2H, m, Ph), 6.79 (1H, d, J7.6 Hz, Ar),
Ethyl 5-(4-chlorophenyl)-3-phenyl-1H-pyrrole-2-carboxyl-
ate (16f). Pale yellow powder; yield 55%; mp 1808C; (lit.
1
3
.61 (1H, s, Ar), 6.59 (1H, d, J7.6 Hz, Ar), 5.98 (1H, d,
J7.4 Hz, H-4), 5.96 (2H, s, OCH O), 5.33 (1H, dd, J1.9
1858C); [Found: C, 70.0; H, 5.2; N, 4.4. C19
requires C, 70.05; H, 4.95; N, 4.30%]; d
H
16ClNO
(CDCl
2
2
and 7.4 Hz, H-5), 5.18 (1H, s, H-2), 4.31 (2H, q, J7.1 Hz,
OCH CH ), 1.31 (3H, t, J7.1 Hz, CH ); d (63 MHz,
H
,
3
250 MHz): 9.70 (1H, br s, NH), 7.60±7.50 (4H, m, Ph-H),
7.44±7.30 (5H, m, Ph-H), 6.59 (1H, d, J2.0 Hz, Ar-H),
2
3
3
C
CDCl ): 168.4 (q), 160.8 (q), 148.7 (q), 148.0 (q), 133.2
3
(
1
q), 128.9 (q), 128.5 (2£CH), 128.0 (CH), 127.4 (2£CH),
4.25 (2H, q, J7.1 Hz, CH
2
CH
3
), 1.23 (3H, t, J7.1 Hz,
20.8 (CH), 109.1 (CH), 107.8 (CH), 101.5 (CH ), 95.0
2
CH
2
CH
3
); d
C
(63 MHz, CDCl
3
): 160.1 (q), 135.0 (q), 134.4
(
CH), 79.2 (CH), 62.5 (CH ), 60.3 (CH), 14.0 (CH );
2
(q), 133.6 (q), 133.5 (q), 129.6 (q), 129.5 (2£CH), 129.2
(2£CH), 127.7 (2£CH), 127.2 (CH), 126.1 (2£CH), 119.0
(q), 110.3 (CH), 60.6 (CH ), 14.1 (CH ); EIMS m/z (rel.
2 3
intensity, %): 326 (M , 100), 308 (14), 290 (57), 280
(89), 254 (15), 246 (17), 220 (9), 149 (5), 111 (7), 97
3
1
EIMS m/z (rel. intensity, %): 336 (M -1, 100), 318 (7),
90 (46), 264 99), 192 (4), 135 (5), 106 (7), 85 (14), 71
2
(
1
2
1
1
16); IR (KBr, cm ): 3414, 1734, 1532, 1491, 1445, 1365,
302, 1243, 1118, 1033, 929, 810.