10-Acetyl-2,7-bis(3Ј,3Љ-oxo-3Ј,3Љ-N-pyrrolidinylpropyl)indolo-
[3,2-b]quinoline (10a). The crude diacid (9) (0.3 g, 0.8 mmol)
was dissolved in dry dichloromethane (10 ml) and triethylamine
(1 ml) under argon. The solution was cooled to 0 ЊC and iso-
butylchloroformate (0.38 ml, 2.9 mmol) was gently added. The
mixture was left stirring for 30 min and pyrrolidine (0.20 ml,
2.4 mmol) was added. After 1 hour, the mixture was diluted
with dichloromethane and the organic phase was washed
with water (3 × 100 ml) and the organic layer was separated and
dried over magnesium sulfate. The solvent was evaporated
and the crude product was recrystallised from a mixture of
ethyl acetate and methanol (1 : 9) to give a pure white solid
(0.28 g, 70%). mp 194 ЊC. νmax /cmϪ 2970 and 2932 (–CH2 and –
CH ), 1699 ((CH ) -N–C᎐O), 1653 (=CH–N–C᎐O). δ (500
10-Acetyl-2-bromoindolo[3,2-b]quinoline (11). IR (KBr):
νmax /cmϪ1 1699 (OC᎐O), 1619 (NC᎐O). δ (500 MHz, CDCl3)
᎐
᎐
H
2.95 (3H, s, NCOCH3), 7.52 (1H, t, J7–8,6 7.8, 7-H), 7.70 (1H, t,
J8–7,9 7.8, 8-H), 7.80 (1H, br d, J 9, 3-H), 8.06–8.2 (3H, m, 1-H,
9-H and 4-H), 8.60 (1H, br d, J6–7 7.8, 6-H), 9 (1H, br s, 11-H).
δC (125 MHz, CDCl3) 27.9 (NCOCH3), 116 (C-9), 120.3 (C-11),
120.8, 122.5 (C-6), 124.9 (C-7), 125.6, 128.7, 130.7 (2C, C-4 and
C-1), 131.3 (C-8), 131.9, 132.3 (C-3), 141.8, 144.7, 147.8, 170.0
(CO); m/z (EI) Found: 338.0069 (79 Br, C17H11BrN2O requires
338.0055).
10-Acetyl-2-(2Ј-tert-butoxycarbonylvinyl)indolo[3,2-b]quino-
line. White solid, mp 174–175 ЊC; IR (KBr): νmax /cmϪ1 2977,
2932, 1701 (ester C᎐O), 1634 (amide C᎐O), 1150; δ (500 MHz,
᎐
᎐
3
2
2
H
᎐
᎐
H
MHz, CDCl3) 1.79–1.95 (8H, m, b-H and bЈ-H), 2.71 (4H, t,
J1Ј-2Ј and 1Љ-2Љ7.8, 1Ј-H and 1Љ-H), 2.92 (3H, s, NCOCH3), 3.17–3.25
(4H, m, 2Ј-H and 2Љ-H), 3.32–3.41 (4H, m, a-H and aЈ-H), 3.47–
3.51 (4H, m, a-H and aЈ-H), 7.55 (1H, dd, J8–9 8.5, J8–6 1.8, 8-H),
7.64 (1H, dd, J3–4 8.6, J3–1 1.9, 3-H), 7.82 (1H, s, 1-H), 8.01–8.03
(1H, br m, 9-H), 8.16 (1H, d, J4–3 8.6, 4-H), 8.32 (1H, s, 6-H), 8.93
(1H, br s, 11-H); δC (125 MHz, CDCl3) 24.4 (C-b), 27.6
(NCOCH3), 30.6 and 31.1 (C-2Ј and C-2Љ), 36.3 and 36.7 (C-1Ј
and C-1Љ, 45.7 and 46.6 (C-a), 115.8 (C-9), 121.0 (C-11 and C-6),
126.0, 127.1 (C-1), 127.5 (C*), 128.8 (C-4), 130.2 (C-3), 131.4
(C-8), 131.9, 138.1, 139.9, 144.9, 146.9, 169.6 (NCOCH3), 170.5
(C-3Ј and C-3Љ); m/z (EI) found 510.2597 (C31H34N4O3 requires
510.26.31).
CDCl3) 1.57 (9H, s, C(CH3)3), 2.95 (3H, s, COCH3), 6.53 (1H,
d, J2Ј-1Ј, 16, 2Ј-H), 7.52 (1H, m, 7-H), 7.67 (1H, m, 8-H), 7.78
(1H, d, J1Ј-2Ј 16, 1Ј-H), 7.90 (1H, d, J3–4 8.9, 3-H), 8.0 (1H, d, J1–3
1.8, 1-H), 8.1 (1H, br d, J9–9 1.8, 9-H), 8.2 (1H, d, J4–3 8.9, 4-H),
8.49 (1H, br.d, J6–7 7.6, 6-H), 8.99 (1H, s, 11-H); δC (125 MHz,
CDCl3) 27.6 (COCH3), 28.2 (tert-Bu.Me), 80.7 (tert-Bu.C),
115.8 (C-9), 121.3, 121.8 (C-11), 122.2 (C-6), 124.6 (C-7), 125.6,
126.4 (C-3), 127.3, 129.6 (C-4), 129.9 (C-1), 131.0 (C-7), 131.9,
132.5, 141.6, 142.8 (C-2Ј), 146.8, 148.1, 166.2 (ester CO), 169.7
(amide CO); m/z (EI) found 386.1637 (C24H22N2O3 requires
386.163).
10-Acetyl-2-(2Ј-N-pyrrolidinylcarbonylethyl)-10H-indolo-
[3,2-b]quinoline. White solid, mp 163–165 ЊC (from EtOAc/
ether, 4 : 1); IR (KBr): νmax/cmϪ1 2986, 2931, 1697 (amide CO),
1652 (amide CO); δH (500 MHz, CDCl3) 1.78–1.93 (4H, m,
b-H), 2.70 (2H, t, J1Ј-2Ј 7.7, 1Ј-H), 2.92 (3H, s, amideCH3),
3.22 (2H, t, J2Ј-1Ј, 7.7, 2Ј-H), 3.33 (2H, t, Ja-a, 6.7, a-H), 3.48 (2H,
t, Ja-a 6.7, a-H), 7.48 (1H, t, J7–6 7.7, 7-H), 7.60–7.64 (2H, m,
3-H, 8-H), 7.79 (1H, s, 1-H), 8.13 (br d, J9–8 8.0, 9-H), 8.16 (1H,
d, J4–3 8.7, 4-H), 8.46 (1H, d, J6–7 7.7, 6-H), 8.86 (1H, br s,
11-H); δC (125 MHz, CDCl3) 24.4 (C-b), 26.0 (C-b), 27.6 (amide
CH3), 31.1 (C-2Ј), 36.3 (C-1Ј), 45.7 (C-a), 46.6 (C-a), 115.9
(C-9), 120.9 (C-11), 121.8 (C-6), 124.4 (C-7), 125.8, 126.9,
127.3, 129.0, 129.8, 130.1 (C-8 or C-3), 130.4 (C-8 or C-3),
131.5, 141.4, 145.0, 147.0, 169.7 (amide CO), 170.4 (C-3Ј).
2,7-Bis(3Ј,3Љ-N-pyrrolidinylpropyl)-10H-indolo[3,2-b]quino-
line (3a). The diamide (10) (0.1 g, 0.2 mmol) was dissolved in
dry tetrahydrofuran (1 ml) under argon. A solution of 1 M
lithium aluminium hydride in tetrahydrofuran (2 ml, 2 mmol)
was added carefully at 0 ЊC and the mixture was then left to
reflux for 30 min. The reaction mixture was quenched first with
water (0.076 ml), then with a solution of 15% aqueous sodium
hydroxide (0.076 ml) and finally with more water (0.230 ml).
More tetrahydrofuran (1 ml) was added and the reaction was
put back to reflux for 20 min. After a hot filtration of the pre-
cipitate, the filtrate was evaporated leaving a yellow oil, which
was purified by flash chromatography using a mixture of
(DCM/MeOH, 1 : 4). A pure yellow oil was obtained (0.039 g,
44%). νmax /cmϪ 3314 (N–H), 2934 (–CH2), 1615 (aromatic
ring), 1490 (–CH2). δH (500 MHz, CDCl3) 1.76–1.80 (8H, m,
b-H and bЈ-H), 1.88–2.02 (4H, m, 2Ј-H and 2Љ-H), 2.50–2.55
(12H, m, a-H and aЈ-H and 3Ј-H and 3Љ-H), 2.78–2.88 (4H, m,
1Ј-H and 1Љ-H), 7.19–7.27 (2H, m, 8-H and 9-H), 7.46 (1H, dd,
J3–4 8.7, J3–1 1.6, 3-H), 7.57 (1H, s, 1-H), 7.78 (1H, s, 11-H), 8.21
(1H, d, J4–3 8.7, 4-H), 8.31 (1H, s, 6-H), 9.37 (1H, br s, N–H);
δC (125 MHz, CDCl3) 23.4 (C-b and C-bЈ), 30.3 and 31.1 (C-2Ј
and C-2Љ), 33.7 and 33.9 (C-1Ј and C-1Љ), 53.9 and 54.1 (C-a
and C-aЈ), 55.9 and 56.0 (C-3Ј and C-3Љ), 110.8 (C-9), 112.5
(C-11), 121.3 (C-6), 122.1, 125.3 (C-1), 127.0, 127.9 (C-3), 128.9
(C-4), 130.1 (C-8), 133.2, 133.8, 138.9, 142.2, 143.0, 146.0;
m/z (EI) found 440.2944, (C29H36N4 requires 440.2939).
2-(3Ј-N-Pyrrolidinylpropyl)-10H-indolo[3,2-b]quinoline (12).
IR (KBr, film): νmax /cmϪ 3312 (N–H), 2936 (–CH2). δH (500
MHz, CDCl3) 1.76–1.84 (4H, m, b-H), 1.96–2.03 (2H, m, 2Ј-H),
2.53–2.58 (6H, m, a-H and 3Ј-H), 2.84 (2H, t, J1Ј-2Ј 7.6, 1Ј-H),
7.28 (1H, td, J7–6 7.7, J7–9 0.8, 7-H), 7.41 (1H, d, J9–8 8.1, 9-H),
7.47 (1H, d, J3–4 8.7, 3-H), 7.54 (1H, td, J8–9 8.1, J8–6 1.2, 8-H),
7.59 (1H, s, 1-H), 7.83 (1H, s, 11-H), 8.22 (1H, d, J4–3 8.7, 4-H),
8.5 (1H, d, J6–7 7.7, 6-H), 9.12 (1H, N–H). δC (125 MHz, CDCl3)
23.5 (2CH2, C-b), 30.3 (C-2Ј), 33.9 (C-1Ј), 54.2 (2CH2, C-a),
56.0 (C-3Ј), 110.9 (C-9), 112.7 (C-11), 120.1 (C-7), 122.0
(C-6), 122.2, 125.3 (C-1), 127.0, 128.1 (C-3), 128.8 (C-4), 129.5
(C-8), 132.7, 139.1, 143.2, 143.6, 145.9; m/z (EI) found:
329.1908 (C22H23N3 requires 329.1892)
2,7-Bis(3Ј,3Љ-N-piperidinylpropyl)-10H-indolo[3,2-b]quinoline
(3b). IR (KBr): νmax /cmϪ 3314 (N–H), 2934 (–CH2), 1615
(aromatic ring), 1490 (–CH2). δH (500 MHz, CDCl3) 1.44 (4H,
br s, c-H and cЈ-H), 1.60–1.63 (8H, m, b-H and bЈ-H), 1.92–2.00
(4H, m, 2Ј-H and 2Љ-H), 2.41–2.44 (12H, m, a-H and aЈ-H and
3Ј-H and 3Љ-H), 2.77–2.82 (4H, m, 1Ј-H and 1Љ-H), 7.26–7.34
(2H, m, 8-H and 9-H), 7.47 (1H, d, J3–4 8.7, 3-H), 7.61 (1H, s,
1-H), 7.85 (1H, s, 11-H), 8.20 (1H, d, J4–3 8.7, 4-H), 8.31 (1H, s,
6-H), 8.80 (1H, br s, N–H). δC (125 MHz, CDCl3) 24.2 (6C, C-b,
C-bЈ, C-c, C-cЈ), 28.0 and 28.6 (C-2Ј and C-2Љ), 33.7 and 33.8
(C-1Ј and C-1Љ), 53.3 and 54.4 (4C, C-a and C-aЈ), 58.6 and 58.7
(C-3Ј and C-3Љ), 110.7 (C-9), 112.7 (C-11), 121.2 (C-6), 122.1,
125.3 (C-1), 127.0, 128.0 (C-3), 128.8 (C-4), 130.2 (C-8), 133.1,
133.8, 138.9, 142.1, 143.0, 145.9. m/z (EI) found 468.3545,
(C31H40N4 requires 468.3252).
FRET DNA melting assay
All oligonucleotides and their fluorescent conjugates were
purchased from Oswel (Southampton, UK). DNA was initially
dissolved as a stock 50 µM solution in purified water; further
dilutions were carried out in the relevant buffer.
The ability of the compounds to stabilise G-quadruplex
DNA was investigated using a fluorescence resonance energy
transfer (FRET) assay modified to be used as a high-through-
put screen in a 96-well format. The labelled oligonucleotide
F21T
(5Ј-FAM-dGGG(TTAGGG)3-TAMRA-3Ј;
donor
fluorophore FAM: 6-carboxyfluorescein; acceptor fluorophore
TAMRA: 6-carboxy-tetramethylrhodamine) used as the FRET
probe was diluted from stock to the correct concentration
(400 nM) in a 50 mM potassium cacodylate buffer (pH 7.4)
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 9 8 1 – 9 8 8
986