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L. D. Raev et al.
LETTER
(7) Ethyl 2-Amino-4-(2-hydroxy-5-nitrophenyl)-6-oxo-
(5) Claremon, D. A.; Hirshfield, J.; Lumma, P. K.; McClure, D.
E.; Springer, J. P. Synthesis 1986, 144.
1,4,5,6-tetrahydro-3-pyridinecarboxylate (6f)
(unpublished data): 1H NMR (400 MHz, DMSO-d6):
d = 1.04 (m, 3 H, CH3), 2.50 (d, 2J = 16.2 Hz, 1 H, 5-HA),
2.80 (dd, 3J = 7.3 Hz, 2J = 16.2 Hz, 1 H, 5-HB), 3.95 (m, 2 H,
OCH2), 4.40 (d, 3J = 7.3 Hz, 1 H, 4-H), 7.01 (d, 1 H, 3¢-H),
7.75 (s, 1 H, 6¢-H), 8.03 (d, 1 H, 4¢-H.), 6.20–7.80 (br, 2 H,
NH2), 9.80 (s, 1 H, NH or OH), 11.35 (br s, 1 H, OH or NH).
13C NMR (100.6 MHz, DMSO-d6): d = 14.8 (CH3), 30.5
(C-4), 36.9 (C-5), 58.6 (O-CH2), 75.0 (C-3), 115.9
(Carom.-3¢), 123.1 (Carom.-6¢), 124.7 (Carom.-4¢), 131.7
(Carom.-1¢), 139.8 (Carom.-5¢), 154.6 (C-2), 162.0 (Carom.-2¢),
168.2 (C=O, ester), 170.3 (C=O, lactam).
(6) Ethyl 2-Amino-4-(2-hydroxyphenyl)-6-oxo-1,4,5,6-
tetrahydro-3-pyridinecarboxylate (6a) (unpublished
data): 1H NMR (400 MHz, DMSO-d6): d = 1.02 (t, J = 7.0
Hz, 3 H, CH3), 2.51 (d, 2J = 16.0 Hz, 1 H, 5-HA), 2.80 (dd,
2J = 16.0 Hz, 3J = 7.3 Hz, 1 H, 5-HB), 3.99 (m, 2 H, OCH2),
4.35 (d, 3J = 7.3 Hz, 1 H, 4-H), 6.67 (m, 1 H, 6¢-H), 6.80 (m,
2 H, 3¢-H, 5¢-H), 6.99 (m, 1 H, 4¢-H.), 6.00–8.00 (br, 2 H,
NH2), 9.45 (s, 1 H, NH or OH), 9.59 (s, 1 H, OH or NH). 13
C
NMR (100.6 MHz, DMSO-d6): d = 13.5 (CH3), 28.7 (C-4),
36.1 (C-5), 57.4 (O-CH2), 74.9 (C-3), 114.0 (Carom.), 117.9
(Carom.), 125.5 (Carom.), 126.5 (Carom.), 128.4 (Carom.), 152.4
(C-2¢), 153.4 (C-2.), 167.4 (C=O, ester), 170.0 (C=O,
lactam).
Salient NMR signals: O-Acetyl derivative (15a): mp 170–
172 °C (toluene). 1H NMR (300 MHz, DMSO-d6): d = 2.32
(s, 3 H, OCOCH3), 7.03–7.25 (m, 6 H, 4Harom and NH2), 9.73
(s, 1 H, lactam-NH). N-Acetyl derivative (16a): mp 184–186
°C (EtOH). 1H NMR (300 MHz, DMSO-d6): d = 2.21 (s, 3
H, NCOCH3), 9.61 (br s, 1 H, OH), 10.68 (s, 1 H, amide-
NH), 11.49 (s, 1 H, lactam-NH). O,N-Diacetyl derivative
(17a): mp 180–181 °C (EtOH). 1H NMR (300 MHz, CDCl3):
d = 2.23 (s, 3 H, NCOCH3), 2.34 (s, 3 H, OCOCH3), 10.96
(s, 1 H, amide-NH), 11.98 (s, 1 H, lactam-NH). 13C NMR (75
MHz, CDCl3): d = 21.0 (OCOCH3), 25.3 (NCOCH3).
Salient 1H NMR signals: N-Acetyl derivative (16b): mp
218–220 °C (2-PrOH). 1H NMR (250 MHz, DMSO-d6):
d = 2.23 (s, 3 H, NCOCH3), 10.72 (s, 1 H, amide-NH), 11.40
(s, 1 H, lactam-NH), 11.5 (br s, 1 H, OH). O,N-Diacetyl
derivative (17b): mp 165–166.5 °C (2-PrOH). 1H NMR (250
MHz, CDCl3): d = 2.29 (s, 3 H, NCOCH3), 2.40 (s, 3 H,
OCOCH3), 11.12 (s, 1 H, amide-NH), 12.01 (s, 1 H, lactam-
NH).
(8) Raev, L. D.; Ivanov, I. C. Third National Congress of
Pharmacy (Abstracts), 17-19 October 1996, Sofia –
Panichishte (Bulgaria); poster 11.P5.
Synlett 2004, No. 9, 1584–1588 © Thieme Stuttgart · New York