Arkivoc 2019, ii, 0-0
Palomba, M. et al.
09 (m, 2H), 2.62-2.44 (m, 2H), 2.41-2.31 (m, 1H), 2.26-2.15 (m, 1H), 1.32 (t, 3H, J 7.1 Hz), 1.23 (t, 3H, J 7.1 Hz);
3C NMR (100 MHz, CDCl3): δ = 173.5, 172.0, 161.9, 136.9, 130.0, 127.5, 124.4, 122.0, 120.3, 112.3, 103.3, 61.8,
60.9, 52.3, 30.5, 27.0, 14.1, 14.0; FT-IR (KBr) υmax 3350, 3270, 1734, 1646, 1530 cm-1. HRMS (ESI-TOF) m/z:
[M+H]+ calcd for C18H23N2O5 347.1607; found: 347.1618.
Ethyl (2R)-2-[(1H-indol-2ylcarbonyl)amino]-3-mercaptopropanoate, 3f: white solid; yield 61%; m.p. 118-
121°C; []21D = -35.0 (c 1.0, MeOH). 1H NMR (400 MHz, DMSO d6, 25°C); δ = 11.61 (brs, 1H,), 8.91 (d, 1H, J 7.9
Hz), 7.63 (d, 1H, J 7.9 Hz), 7.43 (d, 1H, J 8.3 Hz), 7.23-7.16 (m, 2H), 7.10-7.0 (m, 1H), 4.87-4.78 (m, 1H), 3.67 (s,
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3H), 3.37-3.30 (m, 2H), 3.19 (dd, 1H, J 9.8, 13.6 Hz); C NMR (100 MHz, CDCl3): δ = 170.7, 161.4, 136.4, 129.7,
127.5, 124.9, 122.2, 120.8, 111.8, 103.7, 52.9, 52.3, 41.2; FT-IR (KBr) υmax 3338, 3256, 1734, 1622, 1540 cm-1.
HRMS (APCI-TOF) m/z: [M+H]+ calcd for C13H16N2O3S 279.0803; found: 279.0799.
Ethyl (2S)-2-{[(5-methoxy-1H-indol-2yl)carbonyl]amino}-3-methylbutanoate, 3g:44 white solid; yield 53%;
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m.p. 105-110°C. H NMR (400 MHz, CDCl3, 25°C, TMS): δ = 9.98 (brs, 1H), 7.38 (d, 1H, J 8.9 Hz), 7.07 (d, 1H, J
2.1 Hz), 6.98 (dd, 1H, J 2.1, 8.9 Hz), 6.94 (d, 1H, J 1.4 Hz), 7.90-6.87 (brs, 1H), 4.83 (dd, 1H, J 5.1, 8.7 Hz), 4.36-
4.21 (m, 2H), 3.87 (s, 3H), 2.40-2.29 (m, 1H), 1.34 (t, 3H, J 7.1 Hz), 1.06 (t, 6H, J 7.1 Hz); 13C NMR (100 MHz,
CDCl3): δ = 172.1, 161.6, 154.5, 132.0, 130.5, 127.8, 115.9, 113.0, 102.4, 102.1, 61.5, 57.3, 55.6, 31.7, 19.0,
18.0, 14.2.
Ethyl (2S)-2-{[(5,6-dimethoxy-1H-indol-2yl)carbonyl]amino}-3-methylbutanoate, 3h: white solid; yield 64%;
m.p. 165-168°C; []20D = -20.0 (c 1.0, CHCl3). 1H NMR (400 MHz, CDCl3, 25°C, TMS): δ = 10.42 (brs, 1H), 7.02 (s,
1H), 6.96 (s, 1H), 6.94 (d, 1H, J 1.6 Hz), 6.87 (brd, 1H, J 8.6 Hz), 4.84 (dd, 1H, J 5.4, 8.7 Hz), 4.30-4.21 (m, 2H),
3.95 (s, 3H), 3.92 (s, 3H), 2.34-2.25 (m, 1H), 1.30 (t, 3H, J 7.1 Hz), 1.07 (d, 3H, J 6.8 Hz), 1.04 (d, 3H, J 6.8 Hz); 13C
NMR (100 MHz, CDCl3): δ = 172.4, 161.9, 149.3, 145.9, 131.9, 128.6, 120.3, 103.2, 102.1, 94.4, 61.6, 57.3, 56.0,
55.8, 31.5, 19.2, 18.1, 14.3; FT-IR (KBr) υmax 3376, 3278, 1733, 1627, 1539 cm-1. HRMS (ESI-TOF) m/z: [M+H]+
calcd for C18H25N2O5 349.1763; found: 349.1770.
Ethyl (2S)-2-{[(5-fluoro-1H-indol-2yl)carbonyl]amino}-3-methylbutanoate, 3i: white solid; yield 47%; m.p.
142-145°C; []21D = +26.7 (c 1.2, CHCl3). 1H NMR (400 MHz, CDCl3, 25°C, TMS): δ = 9.69 (brs, 1H), 7.40 (dd, 1H, J
4.3, 8.9 Hz), 7.31 (dd, 1H, J 2.0, 9.1 Hz), 7.07 (dt, 1H, J 2.3, 9.1 Hz), 6.95 (brs, 1H), 6.77 (brd, 1H, J 8.6 Hz), 4.78
(dd, 1H, J 5.0, 8.7 Hz), 4,35-4,23 (m, 2H), 2.38-2.28 (m, 1H), 1.34 (t, 3H, J 7.1 Hz), 1.11-1.02 (m, 6H); 13C NMR
(100 MHz, CDCl3): δ = 171.8, 161.2, 158.1 (d, JC-F 234.9 Hz), 133.0, 131.7, 127.7, 113.6 (d, JC-F 26.6 Hz), 112.9 (d,
JC-F 9.6 Hz), 106.2 (d, JC-F 23.3 Hz), 102.5 (d, JC-F 5.2 Hz), 61.5, 57.3, 31.7, 18.9, 17.9, 14.2; FT-IR (KBr) υmax 3355,
3257, 1723, 1646, 1542 cm-1. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C16H20FN2O3 307.1458; found: 307.1467.
Ethyl (2S)-3-methyl-2-{[(5-nitro-1H-indol-2yl)carbonyl]amino}butanoate, 3j: Yellow solid; yield 79%; m.p.
119-122°C; []21D = -9.3 (c 1.1, CHCl3). 1H NMR (400 MHz, CDCl3, 25°C, TMS): δ = 10.50 (brs, 1H), 8.29 (d, 1H, J
8.0 Hz), 8.04 (d, 1H, J 7.8 Hz), 7.30 (t, 1H, J 8.0 Hz), 7.12 (d, 1H, J 2.3 Hz), 6.85 (brd, 1H, J 8.6 Hz), 4.82 (dd, 1H, J
4.8, 8.6 Hz), 4.33-4.25 (m, 2H), 2.37-2.31 (m, 1H), 1.36 (t, 3H, J 7.1 Hz), 1.06 (d, 3H, J 6.9 Hz), 1.03 (d, 3H, J 6.9
Hz); 13C NMR (100 MHz, CDCl3): δ = 171.9, 160.1, 133.4, 132.8, 131.2, 130.0, 129.2, 121.8, 120.1, 103.6, 61.7,
57.4, 31.8, 19.0, 17.9, 14.2; FT-IR (ATR) υmax 3467, 3439, 1749, 1673, 1548 cm-1. HRMS (ESI-TOF) m/z: [M+H]+
calcd for C16H20N3O5 334.1403; found: 334.1409.
Ethyl (2S)-2-[(1H-indol-3-ylacetyl)amino]-3-methylbutanoate, 3k: brown oil; yield 44%; []20 = +18.0 (c 1.0,
D
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CHCl3). H NMR (400 MHz, CDCl3, 25°C, TMS): δ = 8.99 (brs, 1H), 7.60 (d, 1H, J 7.8 Hz), 7.39 (d, 1H, J 8.1 Hz),
7.23 (t, 1H, J 7.9 Hz), 7.15 (t, 1H, J 8.0 Hz), 7.08 (brs, 1H), 6.30 (d, 1H, J 8.8 Hz), 4.56 (dd, 1H, J 5.0, 8.8 Hz), 4.17-
4.05 (m, 2H), 3.80 (d, 2H, J 2.4 Hz), 2.12-2.01 (m, 1H), 1.21 (t, 3H, J 7.1 Hz), 0.84 (d, 3H, J 6.8 Hz), 0.69 (d, 3H, J
6.8 Hz); 13C NMR (100 MHz, CDCl3): δ = 171.9 (2C), 136.3, 126.9, 124.2, 122.3, 119.9, 118.5, 111.5, 108.1, 61.4,
57.2, 33.5, 31.0, 18.9, 17.5, 14.0; FT-IR (ATR) υmax 3405, 3303, 1731, 1651, 152
1 cm-1. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C17H23N2O3 303.1709; found: 303.1714.
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