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(t, J = 6.4 Hz, 2 H), 6.98 (d, J = 7.7 Hz, 1 H), 6.87 (d, J = 8.0 Hz, 1 H),
5.89–5.87 (m, 1 H), 5.67 (br. s, 1 H), 5.22 (d, J = 10.5 Hz, 1 H), 5.06–
5.02 (m, 1 H), 4.25 (t, J = 13.6 Hz, 1 H), 4.03 (d, J = 15.8 Hz, 1 H),
3.02 (s, 3 H), 2.95 (s, 3 H), 2.48–2.45 (m, 1 H), 2.36 (s, 3 H), 1.38–1.34
(m, 1 H) ppm. 13C NMR (126 MHz, CDCl3): δ = 175.8, 169.0, 143.1,
134.2, 133.7, 132.1, 131.1, 129.5, 128.4, 127.8, 127.0, 124.5, 124.1,
123.3, 123.0, 119.6, 116.7, 116.4, 115.2, 115.1, 112.9, 64.1, 43.1, 31.2,
21.4 ppm. IR (film): ν = 3219, 3153, 3080, 2936, 2855, 1716, 1590,
˜
1493, 1427, 1409, 1377, 1339, 1283, 1157, 1050, 1015, 795, 749, 706,
665 cm–1. HRMS (ESI): calcd. for C27H22N3O3S [M – H]– 468.1387;
142.3, 138.5, 137.7, 134.7, 129.5, 128.7, 127.4, 126.8, 123.5, 119.6, found 468.1374.
109.5, 63.4, 60.0 (2 ×), 57.9, 42.0, 33.5, 31.2, 21.4 ppm. IR (film): ν =
˜
3257, 2942, 2865, 2822, 1729, 1658, 1458, 1330, 1247, 1158, 984,
868, 816, 745, 662, 605, 544, 522, 509, 507 cm–1. HRMS (FAB): calcd.
for C23H26N3O5S [M + H]+ 456.1593; found 456.1608.
Compound 21: To a solution of 5d (30 mg, 0.060 mmol) in CH2Cl2
(2 mL) was added tBuOCl (10 μL, 0.090 mmol), and the mixture was
stirred at room temperature for 1 h and then concentrated under
reduced pressure. The crude residue was used in the next step with-
out further purification. To the solution of the residue in EtOH
(4 mL) was added concentrated HCl (1 μL), and the mixture was
stirred at room temperature for 30 min and then quenched with
water. The mixture was extracted with EtOAc, and the organic layer
washed with water and brine, dried with Na2SO4, and concentrated
under reduced pressure. Purification of the crude residue by flash
column chromatography on silica gel (40 % EtOAc/hexane) gave 21
(31.9 mg, 98 %) as a white amorphous substance; [α]D21 = +42.7 (c =
0.51, CHCl3). 1H NMR (CDCl3): δ = 7.82 (d, J = 8.0 Hz, 1 H), 7.52–7.45
(m, 3 H), 7.36 (t, J = 7.7 Hz, 1 H), 7.22–7.16 (m, 4 H), 7.07 (d, J =
7.4 Hz, 1 H), 6.34 (d, J = 7.7 Hz, 1 H), 5.97–5.91 (m, 1 H), 5.73 (s, 1
H), 5.09 (d, J = 10.6 Hz, 1 H), 4.90 (d, J = 17.2 Hz, 1 H), 4.33–4.29
(m, 2 H), 4.10 (td, J = 13.1, 5.7 Hz, 3 H), 2.72–2.70 (m, 1 H), 2.37 (s,
3 H), 1.24 (dd, J = 14.5, 7.3 Hz, 3 H) ppm. 13C NMR (126 MHz, CDCl3):
δ = 194.1, 178.1, 155.6, 147.8, 143.2, 139.0, 137.8, 134.7, 131.9,
131.54, 131.51, 131.3, 130.0, 129.5, 126.90, 128.87, 125.2, 124.4,
Compound 4d: Compound 4d was obtained according to the pro-
1
cedure for 4a. [α]D22 = –59.9 (c = 1.03, CHCl3). H NMR (CDCl3): δ =
8.01 (d, J = 8.0 Hz, 1 H), 7.91 (s, 1 H), 7.56–7.50 (m, 4 H), 7.29–7.28
(m, 1 H), 7.19 (d, J = 8.0 Hz, 2 H), 7.02 (d, J = 7.7 Hz, 1 H), 6.91 (s, 1
H), 6.79 (d, J = 7.7 Hz, 1 H), 6.17–6.11 (m, 1 H), 5.74 (s, 1 H), 5.18 (d,
J = 10.3 Hz, 1 H), 5.00 (d, J = 17.2 Hz, 1 H), 4.03–3.99 (m, 2 H), 2.68
(d, J = 14.6 Hz, 1 H), 2.38 (s, 3 H), 1.91–1.85 (m, 1 H) ppm. 13C NMR
(126 MHz, CDCl3): δ = 194.5, 174.3, 146.7, 143.3, 141.4, 141.2, 137.6,
134.9, 133.0, 132.8, 131.0, 129.8, 129.6, 127.2, 126.9, 124.5, 124.3,
124.0, 118.8, 109.5, 69.3, 66.6, 31.4, 21.5, 14.1 ppm. IR (film): ν =
˜
2979, 2913, 1743, 1716, 1541, 1233, 1087, 965, 914, 744 cm–1. HRMS
(FAB): calcd. for C27H24N3O6S [M + H]+ 518.1386; found 518.1381.
Compound 13: To a solution of 5b (40 mg, 0.105 mmol) in CH2Cl2
(2 mL) was added tBuOCl (0.018 mL, 0.158 mmol), and the mixture
was stirred at room temperature for 1 h and then concentrated
under reduced pressure. The crude residue was used in the next
step without further purification. To the solution of the residue in
119.9, 118.2, 68.3, 66.4, 63.8, 41.5, 29.7, 21.4, 13.7 ppm. IR (film): ν =
˜
3028, 2938, 2858, 1714, 1695, 1612, 1573, 1532, 1475, 1434,
1342, 1299, 1245, 1224, 1157, 1012, 882, 845, 813, 749, 706, 690,
662 cm–1. HRMS (ESI): calcd. for C29H28N3O6S [M + H]+ 546.1693;
found 546.1697.
EtOH (2 mL) and CH2Cl2 (3 mL) was added HCl (1
M in Et2O,
0.10 mL), and the mixture was stirred at room temperature for 3 h
and then concentrated under reduced pressure. Purification of the
residue by flash column chromatography on silica gel (20 % EtOAc/
hexane) gave 13 (28 mg, 73 %) as a white solid; [α]D23 = –26.0 (c =
Compound 22: To a solution of 21 (31.9 mg, 0.0585 mmol) in EtOH
(6 mL) and water (1.5 mL) were added iron (65 mg, 1.16 mmol) and
NH4Cl (65 mg, 1.21 mmol, purchased from Kanto Chemicals). The
mixture was heated at reflux for 1 h and then quenched with water.
The mixture was extracted with EtOAc, and the organic layer
washed with water and brine, dried with Na2SO4, and concentrated
under reduced pressure. Purification of the crude residue by flash
column chromatography on silica gel (50 % EtOAc/hexane) gave 22
(11.9 mg, 43 %) as a white amorphous substance; [α]D27 = +140.7
(c = 0.12, CHCl3). 1H NMR (CDCl3): δ = 7.71 (d, J = 7.7 Hz, 1 H), 7.50–
7.46 (m, 3 H), 7.30–7.27 (m, 3 H), 7.14 (d, J = 8.0 Hz, 2 H), 7.06–7.03
(m, 2 H), 6.74–6.67 (m, 1 H), 5.75 (s, 1 H), 5.35 (d, J = 10.6 Hz, 1 H),
5.21 (d, J = 17.2 Hz, 1 H), 3.89–3.86 (m, 1 H), 3.46–3.44 (m, 1 H),
2.42–2.33 (m, 5 H), 1.72 (t, J = 12.6 Hz, 1 H) ppm. 13C NMR (126 MHz,
CDCl3): δ = 199.4, 166.6 148.1, 143.2, 141.7, 137.4, 135.5, 129.6,
129.2, 127.0, 126.6, 126.2, 126.0, 122.3, 120.3, 116.0, 114.6, 85.0, 61.1,
1
0.10, CHCl3). H NMR (CDCl3): δ = 8.62 (s, 1 H), 7.54 (d, J = 8.0 Hz, 2
H), 7.17 (t, J = 8.3 Hz, 3 H), 6.90 (d, J = 7.7 Hz, 1 H), 6.81 (d, J =
7.7 Hz, 1 H), 5.82–5.74 (m, 2 H), 5.31 (t, J = 5.2 Hz, 1 H), 4.76 (t, J =
8.7 Hz, 1 H), 4.20–4.17 (m, 1 H), 3.55–3.50 (m, 2 H), 2.36 (s, 3 H),
2.17–2.15 (m, 1 H), 1.49–1.44 (m, 1 H) ppm. 13C NMR (126 MHz,
CDCl3): δ = 178.7, 143.2, 140.9, 137.9, 136.9, 134.9, 129.7, 129.5,
128.3, 127.8, 127.0, 126.9, 122.6, 120.4, 109.3, 63.0, 46.1, 44.6, 28.5,
21.4 ppm. IR (film): ν = 3300, 2946, 2863, 1705, 1617, 1494, 1460,
˜
1404, 1327, 1249, 1196, 1155, 1014, 970, 946, 908, 855, 809, 781,
727, 710, 659 cm–1. HRMS (FAB): calcd. for C20H20N2O3S [M]+
368.1195; found 368.1195.
Compound 23: Table 2, Entry 5. To a solution of 5d (12.2 mg,
0.0244 mmol) in CH2Cl2 (2 mL) was added tBuOCl (4.1 μL,
0.037 mmol), and the mixture was stirred at room temperature for
1 h and then concentrated under reduced pressure. The crude resi-
due was used in the next step without further purification. To the
solution of the residue in EtOH (2 mL) was added concentrated HCl
(1 μL), and the mixture was stirred at room temperature for 30 min.
Iron (6.8 mg, 0.122 mmol) and water (0.50 mL) were added to the
solution, and the mixture was heated at reflux for 3 h. The reaction
mixture was then filtered through a pad of Celite, and the filtrate
was concentrated under reduced pressure. The crude residue was
purified by flash column chromatography on silica gel (30 % EtOAc/
hexane) to give 23 (5.4 mg, 47 %) as a colorless oil; [α]D23 = –32.7
(c = 0.09, CHCl3). 1H NMR (CDCl3): δ = 9.51 (s, 1 H), 8.67 (d, J =
8.3 Hz, 1 H), 8.01 (d, J = 8.0 Hz, 1 H), 7.66 (d, J = 8.0 Hz, 2 H), 7.41–
7.29 (m, 3 H), 7.11–7.10 (m, 4 H), 6.09 (s, 1 H), 5.90–5.84 (m, 1 H),
5.20 (d, J = 10.3 Hz, 1 H), 4.76 (d, J = 16.9 Hz, 1 H), 4.14 (d, J =
14.0 Hz, 1 H), 3.70–3.65 (m, 2 H), 3.39 (d, J = 15.8 Hz, 1 H), 2.31 (s,
3 H) ppm. 13C NMR (126 MHz, CDCl3): δ = 143.2, 137.8, 137.7, 134.9,
34.5, 28.2, 21.4 ppm. IR (film): ν = 3150, 3086, 3040, 2960, 2923,
˜
2857, 1702, 1630, 1607, 1570, 1476, 1431, 1285, 1325, 1266, 1232,
1156, 1087, 1019, 990, 910, 875, 813, 741, 668 cm–1. HRMS (FAB):
calcd. for C27H24N3O3S [M + H]+ 470.1538; found 470.1545.
Acknowledgments
This work was supported in part by a Research Grant from the
Uehara Memorial Foundation (to C. T.).
Keywords: Alkaloids · Heterocycles · Rearrangement ·
Cyclization · Diastereoselectivity
[1] A. Numata, C. Takahashi, Y. Ito, T. Takada, K. Kawai, Y. Usami, E. Matsu-
mura, M. Imachi, T. Ito, T. Hasegawa, Tetrahedron Lett. 1993, 34, 2355.
Eur. J. Org. Chem. 2016, 108–115
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