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Y. Sui et al. / Tetrahedron 63 (2007) 5173–5183
740 cmꢁ1. H NMR (300 MHz, CDCl3): d 7.82 (br s, 1H),
7.67–7.64 (m, 1H), 7.29–7.19 (m, 3H), 7.10–7.05 (m, 4H),
6.29 (d, J¼12.0 Hz, 1H), 5.24 (d, J¼12.0 Hz, 1H), 4.17–
4.09 (m, 2H), 2.45 (s, 3H), 2.25 (s, 3H), 1.11 (t, J¼7.1 Hz,
3H); 13C NMR (75 MHz, CDCl3): d 163.7, 137.0, 135.3,
135.2, 133.0, 129.4, 127.8, 126.5, 121.2, 119.9, 118.6,
110.8, 108.5, 90.3, 63.0, 44.2, 21.0, 13.6, 12.1. HRMS
(FAB) m/z calcd for C21H22N2O4 (M+): 366.1580, found:
366.1571; syn-3ba: a yellow oil. [a]2D5 +58.1 (c 0.59,
CHCl3); ee value (47%) was determined by chiral HPLC
(Chiralpak AD-H, hexane/isopropanol¼70:30, 0.5 mL/min,
T¼25 ꢀC): tR(minor)¼12.0 min and tR(major)¼26.2 min.
FTIR (neat): n 3407, 2923, 1745, 1561, 1460, 1311, 1183,
diastereomers were separated by flash chromatography on
silica gel (eluent: petroleum ether/ethyl acetate¼4:1); anti-
3da: a white solid, mp: 132–134 ꢀC. [a]D25 +51.9 (c 0.30,
CHCl3); ee value (90%) was determined by chiral HPLC
(Chiralpak AD-H, hexane/isopropanol¼70:30, 0.5 mL/min,
T¼25 ꢀC): tR(major)¼15.7 min and tR(minor)¼22.5 min.
FTIR (KBr): n 3421, 2937, 1745, 1561, 1485, 1359, 1309,
1
1212, 1035, 800 cmꢁ1 1H NMR (300 MHz, CDCl3):
.
d 7.96 (br s, 1H), 7.24–7.18 (m, 4H), 7.07 (d, J¼7.8 Hz,
2H), 6.88–6.79 (m, 2H), 5.84 (d, J¼11.4 Hz, 1H), 5.27 (d,
J¼11.4 Hz, 1H), 4.09–3.99 (m, 2H), 3.77 (s, 3H), 2.27 (s,
3H), 1.02 (t, J¼7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3):
d 161.5, 152.4, 135.6, 132.6, 129.6, 127.6, 126.5, 125.0,
119.3, 112.1, 111.0, 110.0, 99.2, 90.0, 61.0, 54.0, 42.3,
19.2, 11.7. HRMS (EI): m/z calcd for C21H22N2O5 (M+):
382.1529, found: 382.1527; syn-3da: a white solid, mp:
128–129 ꢀC. [a]D25 +133.3 (c 0.61, CHCl3); ee value (55%)
was determined by chiral HPLC (Chiralpak AD-H, hexane/
isopropanol¼70:30, 0.5 mL/min, l¼254 nm, T¼25 ꢀC):
tR(major)¼14.2 min and tR(minor)¼20.8 min. FTIR (KBr):
3421, 2938, 1744, 1561, 1485, 1456, 1358, 1213, 1176,
1019, 740 cmꢁ1. H NMR (300 MHz, CDCl3): d 7.87 (br
1
s, 1H), 7.56–7.53 (m, 1H), 7.24 (d, J¼8.1 Hz, 2H), 7.18–
7.15 (m, 1H), 7.08–7.04 (m, 4H), 6.27 (d, J¼11.9 Hz, 1H),
5.31 (d, J¼11.9 Hz, 1H), 3.86–3.79 (m, 2H), 2.37 (s, 3H),
2.23 (s, 3H), 0.69 (t, J¼7.1 Hz, 3H); 13C NMR (75 MHz,
CDCl3): d 163.7, 136.9, 135.9, 135.2, 132.9, 129.6, 127.0,
126.9, 121.3, 119.8, 118.7, 110.6, 107.8, 89.8, 62.6, 43.2,
21.0, 13.1, 12.2. HRMS (EI) m/z calcd for C21H22N2O4
(M+): 366.1580, found: 366.1582.
1
1024, 917, 801, 730 cmꢁ1. H NMR (300 MHz, CDCl3):
d 8.01 (br s, 1H), 7.29–7.17 (m, 3H), 7.11–7.06 (m, 3H),
7.00 (d, J¼2.3 Hz, 1H), 6.85, 6.82 (dd, J¼2.4, 8.8 Hz,
1H), 5.87 (d, J¼11.6 Hz, 1H), 5.27 (d, J¼11.6 Hz, 1H),
4.04–3.92 (m, 2H), 3.83 (s, 3H), 2.28 (s, 3H), 0.93 (t,
J¼7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3): d 163.5,
154.3, 137.3, 135.6, 131.2, 129.6, 127.5, 126.7, 122.5,
113.0, 112.9, 111.9, 100.8, 91.9, 62.9, 55.9, 43.5, 21.0,
13.4. HRMS (EI): m/z calcd for C21H22N2O5 (M+):
382.1529, found: 382.1532.
4.2.6. Ethyl 3-(5-(benzyloxy)-1H-indol-3-yl)-2-nitro-3-
p-tolylpropanoate 3ca. The dr value (anti/syn¼45:55)
1
was determined by H NMR signals at d: 1.01 and 0.91.
The diastereomers were separated by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate¼4:1);
anti-3ca: a white solid, mp: 164–166 ꢀC. [a]D25 +11.1 (c
0.36, CHCl3); ee value (89% after recrystallization) was
determined by chiral HPLC (Chiralpak AD-H, hexane/
isopropanol¼70:30, 0.5 mL/min, T¼25 ꢀC): tR(major)¼
19.7 min and tR(minor)¼27.4 min. FTIR (KBr): n 3426,
4.2.8. Ethyl 3-(5-methoxy-1H-indol-3-yl)-3-(4-methoxy-
phenyl)-2-nitropropanoate 3db. The dr value (anti/
1
2984, 1746, 1562, 1482, 1308, 1188, 1021, 734 cmꢁ1. H
1
NMR (300 MHz, CDCl3): d 7.92 (br s, 1H), 7.44–7.33 (m,
5H), 7.21–7.18 (m, 4H), 7.06 (d, J¼8.0 Hz, 2H), 6.96 (d,
J¼2.3 Hz, 1H), 6.90, 6.87 (dd, J¼2.3, 8.8 Hz, 1H), 5.83
(d, J¼11.4 Hz, 1H), 5.25 (d, J¼11.4 Hz, 1H), 5.01 (d,
J¼2.1 Hz, 2H), 4.08–3.99 (m, 2H), 2.27 (s, 3H), 1.01 (t,
J¼7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3): d 163.4,
153.4, 137.5, 137.4, 134.3, 131.6, 129.5, 128.5, 128.3,
127.8, 127.6, 126.7, 121.1, 113.9, 113.6, 111.9, 102.6,
91.7, 70.9, 62.9, 44.1, 21.0, 13.5. HRMS (FAB): m/z calcd
for C27H26N2O5 (M+): 458.1842, found: 458.1831; syn-
3ca: a colorless solid, mp: 141–146 ꢀC; ee value (46%)
was determined by chiral HPLC (Chiralpak AD-H, hex-
ane/isopropanol¼70:30, 0.5 mL/min, T¼25 ꢀC): tR(ma-
jor)¼14.7 min and tR(minor)¼19.7 min. FTIR (KBr): n
3426, 2984, 1746, 1562, 1482, 1455, 1308, 1187, 1021,
syn¼55:45) was determined by H NMR signals at d: 1.03
and 0.86. The diastereomers were separated by flash chro-
matography on silica gel (eluent: petroleum ether/ethyl
acetate¼4:1); anti-3db: a white solid, mp: 105–108 ꢀC; ee
value (82%) was determined by chiral HPLC (Chiralcel
OD-H, hexane/isopropanol¼70:30, 0.5 mL/min, T¼25 ꢀC):
tR(major)¼15.4 min and tR(minor)¼20.9 min. FTIR (KBr):
n 3421, 2928, 1746, 1611, 1562, 1511, 1460, 1373, 1305,
1
1251, 1211, 1177, 1033, 800 cmꢁ1. H NMR (300 MHz,
CDCl3): d 7.97 (br s, 1H), 7.27–7.24 (m, 2H), 7.20–7.17
(m, 2H), 6.86–6.78 (m, 4H), 5.81 (d, J¼11.3 Hz, 1H), 5.27
(d, J¼11.3 Hz, 1H), 4.10–3.99 (m, 2H), 3.77 (s, 3H), 3.74
(s, 3H), 1.03 (t, J¼7.1 Hz, 3H); 13C NMR (75 MHz,
CDCl3): d 163.4, 159.1, 154.2, 131.4, 129.7, 129.3, 126.8,
121.0, 114.2, 114.0, 112.8, 111.9, 101.0, 91.8, 62.9, 55.8,
55.3, 43.7, 13.6. HRMS (EI): m/z calcd for C21H22N2O6
(M+): 398.1478, found: 398.1480; syn-3db: a white solid,
mp: 95–99 ꢀC; ee value (47%) was determined by chiral
HPLC (Chiralcel OD-H, hexane/isopropanol¼70:30,
0.5 mL/min, T¼25 ꢀC): tR(major)¼15.1 min and tR(mi-
nor)¼17.5 min. FTIR (KBr): n 3418, 2935, 1744, 1611,
1560, 1512, 1461, 1372, 1303, 1252, 1211, 1178, 1114,
1
734 cmꢁ1. H NMR (300 MHz, CDCl3): d 7.96 (br s, 1H),
7.46 (d, J¼6.5 Hz, 2H), 7.45–7.34 (m, 3H), 7.25–7.17 (m,
3H), 7.09–7.07 (m, 4H), 6.93 (dd, J¼2.4, 8.7 Hz, 1H),
5.85 (d, J¼11.6 Hz, 1H), 5.24 (d, J¼11.6 Hz, 1H), 5.07 (s,
2H), 4.00–3.92 (m, 2H), 2.27 (s, 3H), 0.91 (t, J¼7.1 Hz,
3H); 13C NMR (75 MHz, CDCl3): d 163.5, 153.5, 137.5,
137.3, 135.6, 131.4, 129.6, 128.5, 127.8, 127.6, 127.5,
126.7, 122.5, 113.8, 113.0, 111.9, 102.6, 91.8, 70.9, 62.9,
43.6, 21.0, 13.4. HRMS (EI): m/z calcd for C27H26N2O5
(M+): 458.1842, found: 458.1847.
1
1028, 801 cmꢁ1. H NMR (300 MHz, CDCl3): d 7.94 (br
s, 1H), 7.24–7.18 (m, 2H), 7.11 (d, J¼8.8 Hz, 1H), 6.99
(d, J¼2.2 Hz, 1H), 6.90 (d, J¼1.6 Hz, 1H), 6.77–6.73 (m,
3H), 5.76 (d, J¼11.6 Hz, 1H), 5.18 (d, J¼11.6 Hz, 1H),
4.00–3.89 (m, 2H), 3.74 (s, 3H), 3.67 (s, 3H), 0.86 (t,
J¼7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3): d 163.4,
159.0, 154.3, 131.2, 130.5, 128.8, 126.7, 122.3, 114.3,
4.2.7. Ethyl 3-(5-methoxy-1H-indol-3-yl)-2-nitro-3-p-tol-
ylpropanoate 3da. The dr value (anti/syn¼62:38) was de-
termined by 1H NMR signals at d: 1.02 and 0.93. The