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E. Erba et al. / Tetrahedron 56 (2000) 9991±9997
1
72%. Mp 1568C (white crystal from EtOH). H NMR 5.73
70%. Mp 97 (white crystals from EtOH). IR 1660
(CvO),1H NMR 0.67 (3H, t, J7.2 Hz, CH3), 1.21±1.28
(2H, m, CH2), 2.10±2.29 (2H, m, CH2), 3.64±3.79 (8H, m,
morpholine), 3.89 (3H, s, OCH3), 5.15 (2H, s, CH2Ph), 7.11
and 8,06(212H, 2d, J8.7 Hz, C6H4OCH3), 7.14±7.28 (8H,
m, ArH), 7.41 (1H, d, J15.2 Hz, CHvCHCO), 7.86 (1H,
d, J15.2 Hz, CHvCHCO), 7.92 (1H, d, J8.0 Hz, H-4).
Calcd for C33H35N3O3 (521.67) C 75.98 H 6.76 N 8.05
found: C 75.72 H 6.95 N 7.89
(2H, s, CH2Ph), 7.10±7.74 (11H, m, ArH), 7.61 (1H, d,
J8.0 Hz, H-3), 8.04 (1H, d, J7.6 Hz, H-5), 8.31 (1H, d,
J8.0 Hz, H-4). Calcd for C22H16N2S (340.45) C 77.62 H
4.74 N 8.23 found: C 77.58 H 5.02 N 8.10.
9-(4-Isopropenyl-cyclohex-1-enylmethyl)-2-(4-methoxy-
phenyl)-9H-pyrido[2,3-b]indole 6e. Yield 59%. Mp 1498C
(white crystal from EtOH). 1H NMR 1.23 (7H, m,
3CH21CH), 1.71 (3H, s, CH3), 3.91 (3H, s, OCH3), 3.62±
3.74 (2H, m, CH2N), 5.10±5.14 (2H, m, CH2vC), 5.70±
5.74 (1H, m, CHvC), 7.07 and 8.18 (212H, 2d, J8.8 Hz,
C6H4OMe), 7.20±7.49 (3H, m, ArH), 7.62 (1H, d, J
8.0 Hz, H-3), 8.08 (1H, d, J7.6 Hz, H-5), 8.34 (1H, d,
J8.0 Hz, H-4). Calcd for C28H28N2O (408.54) C 82.32 H
6.91 N 6.86 found: C 82.41 H 7.06 N 8.48.
3-[1-Benzyl-2-(morpholin-4-yl-butylidenamino)-1H-indol-
3-yl]-1-thien-2-yl-propenone 5e. Yield 52%. Yellow oil.
1
IR 1600 (CvO), H NMR 0.68 (3H, t, J7.2 Hz, CH3),
1.60±1.63 (2H, m, CH2), 2.11±2.26 (2H, m, CH2), 3.65±
3.78 (8H, m, morpholine), 5.15 (2H, s, CH2Ph), 7.10±7.94
(14H, m, ArH). Calcd for C30H31N3O2S (497.60) C 72.41
H 6.28 N 8.44 found: C 72.01 H 6.54 N 8.09.
General procedure for the preparation of [2,9-dialkyl-
9H-pyrido[2,3-b]indol-3-yl]aryl-methanones 7a±f
3-[1(4-Isopropenyl-cyclohex-1-enylmethyl)-2-(1-morpho-
lin-4-yl-propylidenamino)-1H-indol-3-yl]-1(4-methoxy-
phenyl)-propenone 5f. Yield 61%.Yellow oil. IR 1605
1
Compounds 5a±f (1 mmol) were mixed with silica gel
(100 mg) and heated at 180±2008C for 10 h until disappear-
ance of the starting material [TLC, ethyl acetate±cyclo-
hexane (3:2)] yielding 7. The crude reaction product was
puri®ed by column chromatography [pentane±ethyl acetate
(1:0 to 19:1)].
(CvO), H NMR 0.78±2.52 (10H, m, 3CH21CH1CH3),
3.58±3.95 (8H, m, morpholine), 3.89 (3H. s, OCH3), 4.45
(2H, s, CH2N), 4.63±4.78 (2H, m, CH2vC), 5.48±5.59 (1H,
m, CHvC), 6.99±8.06 (10H, m, ArH). Calcd for
C35H41N3O3 (551.73) C 76.19 H 7.49 N 7.62 found: C
75.97 H 7.58 N 7.43.
General procedure for the preparation of 9-alkyl-2-aryl-
9H-pyrido[2,3-b]indoles 6a±e
(9-Benzyl-2-ethyl-9H-pyrido[2,3-b]indol-3-yl)phenyl-
methanone 7a. Yield 51%. Mp 1038C (white crystals from
1
EtOH). IR 1665 (CvO), H NMR 1.38 (3H, t, J7.2 Hz,
Compounds 5a±f (1 mmol) and t-BuOK (3 mmol) were
dissolved in t-BuOH (6 ml) and re¯uxed for 12 h. The
mixture was cooled and the precipitate was ®ltered. The
crude product was dissolved in CH2Cl2 and washed with
water. The organic layer was dried with Na2SO4 ad evapo-
rated. After crystallisation of the residue the pure product 7
was obtained.
CH3), 3.8 (2H, q, J7.2 Hz, CH2), 5.76 (2H, s, CH2Ph),
7.15±7.88 (13H, m, ArH), 7.97 (1H, d, J7.7 Hz, H-5),
8.30 (1H, s, H-4). Calcd for C27H22N2O (390.48) C 83.05
H 5.68 N 7.17 found: C 82.87 H 5.92 N 7.95.
(9-Benzyl-2-ethyl-9H-pyrido[2,3-b]indol-3-yl)-(4-meth-
oxyphenyl)-methanone 7b. Yield 70%. Mp 798C (white
crystals from EtOH). IR 1665 (CvO), H NMR 1.36 (3H,
1
9-Benzyl-2-phenyl-9H-pyrido[2,3-b]indole 6a. Yield
79%. Mp 1318C (white crystals from EtOH). H NMR
t, J7.2 Hz, CH3), 3.03 (2H, q, J7.2 Hz, CH2), 3.90 (3H, s,
OCH3), 5.75 (2H, s, CH2Ph), 6.98 and 7.87 (212H, 2d,
J8.5 Hz, C6H4OMe), 7.26±7.48 (8H, m, ArH), 7.98 (1H,
d, J7.7 Hz, H-5), 8.27 (1H, s, H-4). Calcd for C28H24N2O2
(420.51) C 79.98 H 5.75 N 6.67 found: C 79.74 H 5.96 N
6.38.
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5.80 (2H, s, CH2Ph), 7.23±7.57 (11H, m, ArH), 7.72 (1H,
d, J8.2 Hz, H-3), 8.12 (1H, d, J7.8 Hz, H-5), 8.23 (2H, d,
J8.8 Hz, ArH), 8.40 (1H, d, J8.2 Hz, H-4). Calcd for
C24H18N2 (334.42) C 86.20 H 5.42 N 8.38 found: C 86.05
H 5.51 N 8.14.
(9-Benzyl-2-ethyl-9H-pyrido[2,3-b]indol-3-yl)-(4-bromo-
phenyl)-methanone 7c. Yield 45%. Mp 908C (pale yellow
crystals from EtOH). IR 1650 (CvO), 1H NMR 0.38 (3H, t,
J7.5 Hz, CH3), 3.07 (2H, q, J7.5 Hz, CH2), 5.75 (2H, s,
CH2Ph), 7.26±7.80 (12H, m, ArH), 7.98 (1H, d, J7.7 Hz,
H-5), 8.27 (1H, s, H-4). Calcd for C27H21BrN2O C 69.09 H
4.51 N 5.97 found: C 68.82 H 4.77 N 5.63.
9-Benzyl-2-(4-methoxyphenyl)-9H-pyrido[2,3-b]indole
6b. Yield 68%. Mp 1878C (white crystal from EtOH). H
1
NMR 3.89 (3H, s, OCH3), 5.78 (2H, s, CH2Ph), 7.02 and
8.17 (212H, 2d, J8.9 Hz, C6H4OCH3), 7.10±7.48 (8H, m,
ArH), 7.64 (1H, d, J8.2 Hz, H-3), 8.06 (1H, d, J8.4 Hz,
H-5), 8.35 (1H, d, J8.2 Hz, H-4). Calcd for C25H20N2O
(364.45) C 82.39 H 5.53 N 7.69 found: C 82.15 H 5.76 N
7.38.
(9-Benzyl-2-propyl-9H-pyrido[2,3-b]indol-3-yl)-(4-meth-
oxyphenyl)-methanone 7d. Yield 55%. Mp 1058C (white
crystals from EtOH). IR 1660 (CvO), 1H NMR 0.90±0.97
(3H, t, J7.2 Hz, CH3), 1.80±1.91(2H, m, CH2), 2.96±3.04
(2H, m, CH2), 3.91 (3H, s, OCH3), 5.74 (2H, s, CH2Ph),
6.95±7.88 (12H, m, ArH), 7.98 (1H, d, J7.2 Hz, H-5),
8.26 (1H, s, H-4). Calcd for C29H26N2O2 (434.54) C 80.16
H 6.03 N 6.45 found: C 79.97 H 6.35 N 6.23.
9-Benzyl-2-(4-bromophenyl)-9H-pyrido[2,3-b]indole 6c.
Yield 65%. Mp 1378C (white crystals from EtOH). H
NMR 5.80 (2H, s, CH2Ph), 7.28±8.13 (14H, s, ArH), 8.40
(1H, d, J8.1 Hz, H-4). Calcd for C24H17BrN2 (413.32) C
69.74 H 4.14 N 6.78 found C 69.45 H 4.25 N 6.64.
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9-Benzyl-2-thien-2-yl-9H-pyrido-[2,3-b]indole 6d. Yield