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Extended side chain analogues of 8-aminoquinolines: Synthesis and evaluationof antiprotozoal, antimicrobial, b-hematin inhibition, and cytotoxic activities

Kirandeep Kaur,a Meenakshi Jain,a Shabana I. Khan,cd Melissa R. Jacob,c Babu L. Tekwani,ce Savita Singh,b

Prati Pal Singhb and Rahul Jain*a

Received 20th December 2010, Accepted 19th January 2011

DOI: 10.1039/c0md00267d

We report the synthesis of double, triple and quadruple extended side chain analogues of the

antimalarial drug primaquine and some other 8-aminoquinolines. The synthesized analogues have

exhibited potent antimalarial activities in vitro against both the drug-sensitive D6 strain (IC50 ¼0.19–0.92 mg mL�1) and the drug-resistant W2 strain (IC50¼ 0.12–0.82 mg mL�1) of P. falciparum and in

vivo against drug-sensitive P. berghei infected mice (100% curative at 25 mg kg�1 day�1, and resulted in

either 4/6 or 5/6 cures at 10 mg kg�1 day�1) for the most promising structures. These analogues were also

found to be free of cytotoxic effects at the highest test concentration of 23.8 mg mL�1 in a panel

consisting of six cell lines. The promising 8-aminoquinolines inhibited b-hematin (IC50 ¼ 9.6–20.8 mM)

in vitro underlining the disruption of the heme catabolism pathway in the malaria parasite as their

potential biochemical pathway for antimalarial action. The analogues also displayed potent

antileishmanial activities in vitro against L. donovani promastigotes (IC50 ¼ 1.6–32 mg mL�1;

IC90 ¼ 4–40 mg mL�1) and moderate in vitro antimicrobial activities against a panel of bacteria and

fungi.

Introduction

Primaquine (PQ, 1, Fig. 1), is the only drug active against both

the latent liver forms of the relapsing malaria caused by the

Plasmodium vivax and P. ovale and the gametocytes from all

species of the parasite causing human malaria.1 However, pri-

maquine has a short plasma half-life of approximately 4–6 h,2

presumably due to its rapid metabolism, including oxidative

deamination of the parent side chain leading to the formation of

carboxyprimaquine (2, Fig. 1).3–5 The use of PQ is often asso-

ciated with serious adverse effects as a consequence of its toxic

metabolites generated through cytochrome P450 mediated reac-

tions, which have been considered to be directly responsible for

complications, such as hemolytic anemia.6 PQ toxicity is further

aggravated in people with a genetic deficiency of glucose-6-

phosphate dehydrogenase. Other side effects include mild

aDepartment of Medicinal Chemistry, National Institute of PharmaceuticalEducation and Research, Sector 67, S. A. S. Nagar, Punjab, 160 062, India.E-mail: rahuljain@niper.ac.in; Fax: +91-172-221-4692; Tel: +91-172-229-2024bDepartment of Pharmacology and Toxicology, National Institute ofPharmaceutical Education and Research, Sector 67, S. A. S. Nagar,Punjab, 160 062, IndiacNational Center for Natural Products Research, School of Pharmacy,University of Mississippi, MS, 38677, USAdDepartment of Pharmacognosy, School of Pharmacy, University ofMississippi, MS, 38677, USAeDepartment of Pharmacology, School of Pharmacy, University ofMississippi, MS, 38677, USA

300 | Med. Chem. Commun., 2011, 2, 300–307

anemia, cyanosis and methemoglobinemia. The adverse effects

are further amplified by the fact that PQ must be repeatedly

administered at high doses, owing to its limited oral bioavail-

ability.

Peptide and amino acid derivatives of 1 have been prepared to

reduce the toxicity of the parent drug as well as to suppress the

metabolic pathway leading to 2,7–10 but many of these derivatives

are rapidly hydrolyzed to primaquine by aminopeptidases and

endopeptidases.8,10 It is well known that 4-aminoquinolines

accumulate in the food vacuole through pH trapping and the

presence of the basic aminoalkyl side chain plays an essential role

in b-hematin inhibition.11 However, the role of the basic ami-

noalkyl side chain of 8-aminoquinolines (8-AQ) in b-hematin

inhibition is still an unexplored area of interest. Previous work in

our laboratory has shown that attachment of basic amino acids

to the side chain of 8-AQ led to an overall improvement in the

therapeutic index due to the protection of the parent side chain

functionality.12 Therefore, it is safe to assume that the conversion

of the primary amino group in the parent aminoalkyl side chain

of 8-AQ to a secondary amino group in the designed analogues

may not allow its oxidative deamination, resulting in increased

antimalarial efficacy. Based on these considerations, we

proposed to synthesize 8-aminoquinolines bearing an extended

basic aminoalkyl chain.

Recently, we have demonstrated that 2-tert-butylprimaquine

(BPQ, 3, Fig. 1), an 8-AQ analogue devoid of methemoglobin

toxicity, inhibits b-hematin formation in vitro (IC50 ¼ 2.1–2.9

mM). The observation that 3 binds with heme indicated that its

This journal is ª The Royal Society of Chemistry 2011

Fig. 1 8-Aminoquinolines.

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antimalarial mechanism may arise from the inhibition of heme

crystallization through the formation of a complex with heme,

resulting in the increase of the toxicity of free heme against the

malaria parasite.13 Previously, a small number of other 8-AQ

analogues, including tafenoquine, have also been shown to inhibit

b-hematin formation in vitro.14 We proposed that increasing the

length of side chain in 8-AQ would increase their overall basicity

resulting in greater accumulation in the malaria parasite’s food

vacuole (the site for b-hematin formation).15 Encouraged by the

activity results of previously reported Lys and Orn conjugates of

8-AQ (4, Fig. 1),12 we selected N4-alkylpentane-1,4-diamine as the

basic moiety to be attached to the aminoalkyl side chain of 8-

aminoquinolines, thereby providing compounds analogous to

Lys or Orn conjugates of 8-AQ with increased stability to

aminopeptidases and endopeptidases. We also expect these

extended side chain analogues to be more efficacious than parent

8-AQ especially against chloroquine-resistant (CQR) strains of

P. falciparum, because some 4-aminoquinolines like tert-

Scheme 1 Reagents and conditions: (i) 2-(4-bromopentyl)-1,3-isoindo

This journal is ª The Royal Society of Chemistry 2011

butylisoquine and ferroquine having lipophilic moieties in the side

chain have retained activity against CQR malaria parasites.16–18

Similarly, the attachment of one to three N4-alkylpentane-1,4-

diamine chains to the parent side chain of 8-AQ will increase the

lipophilicity, while increasing or retaining their basicity.

Results and discussion

The extended side chain modified analogues 13–17, 22–25 and

30–33 of 8-AQ were prepared according to the synthetic

methodology shown in Scheme 1. The reaction of PQ (1) or its

analogues 3 or 5–7 with 2-(4-bromopentyl)-1,3-isoindolinedione

in the presence of triethylamine (Et3N) easily provided diones 8–

12 (Scheme 1). The compounds 8–12 upon hydrazinolysis using

hydrazine hydrate in 95% EtOH gave the desired 1,4-diamines,

13–17, in excellent yields except for 17, which was obtained in

54% yield due to the degradation of product during column

chromatography. The latter compounds 13–16, upon repeat

linedione, Et3N, rt, 8 h; (ii) NH2NH2$H2O, EtOH, reflux, 1–6 h.

Med. Chem. Commun., 2011, 2, 300–307 | 301

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condensation reaction with 2-(4-bromopentyl)-1,3-iso-

indolinedione in Et3N gave diones 18–21. The hydrazinolysis

reaction of compounds 18–21, as described earlier, easily affor-

ded 1,4-diamines 22–25. The second repeat of the condensation

and side-chain deprotection reactions afforded 1,4-diamines

30–33 (Scheme 1).

In vitro antimalarial activity of the synthesized compounds was

determined on the basis of plasmodial lactate dehydrogenase

(LDH) activity,19 and expressed as IC50 values versus chloroquine-

sensitive (D6) and chloroquine-resistant (W2) strains of

P. falciparum. The analogues were also evaluated for in vivo blood-

schizontocidal antimalarial activity against P. berghei (sensitive

strain) in a rodent malaria model.20 The in vitro cytotoxicity of

analogues was determined against four human cancer cell lines

(SK-MEL, KB, BT-549, and SK-OV-3) and two noncancerous

cell lines (VERO and LLC-PK1) (obtained from ATCC,

American Type Culture Collection) by neutral red assay.21,22 In

line with the earlier observation that BPQ (3) acts via the inhibition

of b-hematin, the synthesized analogues were also evaluated for b-

hematin inhibitory activity in vitro.13 In view of the use of 8-ami-

noquinolines as potential antileishmanial drugs,1 antileishmanial

activity of the compounds was tested in vitro against a culture of

L. donovani promastigotes by Alamar Blue assay.23,24 The anti-

bacterial activities of the synthesized compounds were evaluated

in vitro against Staphylococcus aureus, methicillin-resistant

S. aureus (MRSA), Mycobacterium intracellulare, Escherichia coli,

and Pseudomonas aeruginosa. The susceptibility of S. aureus and

MRSA to test compounds was determined according to the

procedure as described by the NCCLS.25–28 The susceptibility of

M. intracellulare was done using the modified Alamar Blue

procedure of Franzblau et al.29 The antifungal activities of the

target compounds against pathogenic fungi associated with

opportunistic infections (Candida albicans, C. glabrata, C. krusei,

Cryptococcus neoformans, and Aspergillus fumigatus) were deter-

mined according to NCCLS methods.25–28

Table 1 In vitro antimalarial activity (P. falciparum), cytotoxicity, and b-hemaaminoquinolines (13–17), (22–25), and (30–33)a

Compd.No. R R1 R2

P. falciparum (D6) P. falciparum

IC50

(mg mL�1) SIbIC50

(mg mL�1)

13 H H H 0.57 >41.7 0.8014 H H C(CH3)3 0.19 >125 0.1215 OC4H9 C2H5 H 0.60 >39.6 0.3716 OC5H11 C2H5 H 0.52 >45.7 0.1817 OC8H17 C2H5 H 0.92 >25.8 0.8222 H H H 2.6 >9.1 1.523 H H C(CH3)3 NA — NA24 OC4H9 C2H5 H 0.54 >44.0 0.5825 OC5H11 C2H5 H 0.57 >41.7 0.4830 H H H 2.3 >10.3 1.331 H H C(CH3)3 0.70 >34 0.5632 OC4H9 C2H5 H 0.49 >48.5 0.3533 OC5H11 C2H5 H 0.44 >54.0 0.421 (PQ) 2.0 >11.9 2.8

a IC50 and IC90 are the sample concentration that kills 50% and 90% cells compactive. ‘‘—’’, Not tested. Chloroquine: IC50 ¼ 0.014 mg mL�1, SI¼ 1700 (D6 clmg mL�1, SI ¼ 1565 (D6 clone); IC50 ¼ 0.009 mg mL�1, SI ¼ 2644 (W2 clonfalciparum (D6 or W2). BH inhibition activity: Chloroquine: IC50 ¼ 80 mMPentamidine: IC50 ¼ 1 mg mL�1, IC90 ¼ 3.8 mg mL�1. Amphotericin B: IC50

302 | Med. Chem. Commun., 2011, 2, 300–307

The in vitro antimalarial activity (P. falciparum, D6 and W2

clones), cytotoxicity, b-hematin (BH) inhibition and in vitro

antileishmanial activity results of the tested compounds are

summarized in Table 1. The extended side chain analogues in

general produced high antimalarial activity. The most promising

analogue 14 [R ¼ R1 ¼ H, R2 ¼ C(CH3)3] displayed IC50 values

of 0.19 and 0.12 mg mL�1 against D6 and W2 strains, respectively.

Analogue 16 (R ¼ OC5H11, R1 ¼ C2H5, R2 ¼H), possessed IC50

values of 0.52 and 0.18 mg mL�1 against D6 and W2 strains,

respectively. While analogue 32 (R ¼ OC4H9, R1 ¼ C2H5, R2 ¼H) exhibited IC50 values of 0.49 mg mL�1 for D6 clone and

0.35 mg mL�1 for W2 clone. Most interestingly and importantly,

the extended side chain analogues displayed superior activities

against the drug-resistant W2 strain with high selectivity indices

indicating the promise of this class in the treatment of drug-

resistant malaria. None of the analogues showed cytotoxicity up

to highest test concentration of 23.8 mg mL�1 providing high

selective indices in the range between 9.1 and 198.

Most of the analogues displayed high inhibition of b-hematin

formation in vitro with IC50 values in the range of 7.5 to 20.8 mM

(except compound 22, and 30) indicating it as a potential

biochemical pathway of antimalarial action in this class. The

synthesized analogues also showed promising antileishmanial

activity. The most potent analogues 23 [R¼R1¼H, R2¼C(CH3)3]

and 31 [R¼R1¼H, R2¼C(CH3)3] displayed an IC50 value of 1.6

mg mL�1, and an IC90 in the range of 4–7 mg mL�1, which are

comparable to the standard antileishmanial drug pentamidine

(IC50 ¼ 1 mg mL�1, IC90 ¼ 3.8 mg mL�1). The IC50 values for

remaining analogues were in the range between 2.8 and 32 mg mL�1.

The analogues with extended side chain (13, 14, 22, 23, 30, 31)

were 100% curative at doses of 100, 50 and 25 mg kg�1 day�1 for 4

days (6/6 cures) and suppressive at the lowest test dose of 10 mg

kg�1 day�1 for 4 days (resulting in either 4/6 or 5/6 cures) in vivo in

a P. berghei murine malaria model (Table 2). It can be proposed

that the attachment of basic groups at the side chain leads to the

tin (BH) inhibition and in vitro antileishmanial activity (L. donovani) of 8-

(W2)Cytotoxicity (Vero) BH Inhibition

L. donovani

SIb IC50 (mg mL�1) IC50 (mM)IC50

(mg mL�1)IC90

(mg mL�1)

>29.7 NC 18.5 32 NA>198 NC 7.5 2.8 7.2>64.2 NC 10.2 3.5 7>132 NC 9.6 3.7 7>29.0 NC 15.7 17 32>15.8 NC 75 4.2 40— NC >1000 1.6 4>41.0 NC 19.7 14 32>49.5 NC 20.8 3.5 7>18.3 NC 75 5 40>42.5 NC 10.2 1.6 7.3>68 NC 10.7 3.2 7>56.6 NC 11.2 3.1 7>8.5 NC >1000 19.9 NA

ared to vehicle control. NC, not cytotoxic up to (23.8 mg mL�1). NA, Notone); IC50 ¼ 0.1 mg mL�1, SI¼ 238 (W2 clone). Artemisinin: IC50 ¼ 0.015e). b Selectivity index (SI) is the ratio of IC50 in Vero cells to IC50 in P., BPQ: IC50 ¼ 2.9 mM, PQ: IC50 > 1000 mM. Antileishmanial activity:¼ 0.19 mg mL�1, IC90 ¼ 0.35 mg mL�1.

This journal is ª The Royal Society of Chemistry 2011

Table 2 In vivo (P. berghei) antimalarial activity of 8-aminoquinolines (13–17), (22–25), and (30–33)a,b

Compd. No.

P. berghei

(10 mg kg�1 day�1 � 4, oral) (25 mg kg�1 day�1 � 4, oral) (50 mg kg�1 day�1 � 4, oral) (100 mg kg�1 day�1 � 4, oral)

13 (5/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative14 (5/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative15 — — — (0/6) Inactive16 — — — (0/6) Inactive17 — — — (0/6) Inactive22 (4/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative23 (5/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative24 — — — (0/6) Inactive25 — — — (0/6) Inactive30 (5/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative31 (4/6) Suppressive (6/6) Curative (6/6) Curative (6/6) Curative32 — — — (0/6) Inactive33 — — — (0/6) Inactive

a The term ‘curative’ indicates complete elimination of malaria parasites from the body, and animals survive up to day D + 60. The term ‘suppressive’indicates that all of the treated animals show negative parasitemia up to D + 7. However, by D + 60, some mice die, and some survive with completeelimination of parasitemia as indicated by numbers given in parentheses. The term ‘inactive’ indicates that the treated animals show positive parasitemiaeither on D + 4 or D + 7 and usually die by D + 14. b ‘‘—’’, Not tested.

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protection of the primary amino function against metabolism to

inactive or toxic metabolites, resulting in increased antimalarial

activity. However, to our surprise, all extended side chain

analogues of 4,5-disubstituted primaquine (15, 16, 24, 25, 32, and

33) were devoid of antimalarial activity in vivo with all mice dying

by D + 14 at the primary test dose of 100 mg kg�1.

The antibacterial activities of potential 8-AQ are reported in

Table 3. None of the analogues were active against P. aeruginosa

and E. coli (data not shown). The analogues 15–17, 24, 25, 32 and

33 possessed moderate activity against S. aureus exhibiting IC50

values in the range of 8.6–13.6 mg mL�1, and MIC values of 20 mg

mL�1. Except for analogue 17, all were bactericidal at 20 mg mL�1.

The compounds were also active against MRSA with IC50 values

ranging between 6.5–13.4 mg mL�1, MIC and MBC values of 10–

20 mg mL�1. The analogues 14, 25, 32 and 33 showed moderate

activity against M. intracellulare with IC50 values of 9–17.8 mg

mL�1, and MIC and MBC of 20 mg mL�1 for some analogues.

The in vitro antifungal activities of 8-aminoquinolines against

C. neoformans are summarized in Table 3. None of the analogues

were active against C. albicans, C. glabrata, C. krusei, and

A. fumigatus (data not shown). Most of the extended side chain

8-aminoquinolines 13–17, 22–25 and 30–33 were active against

C. neoformans with IC50 values ranging between 5.5 and 12.1 mg

mL�1. The analogues 16, 25, and 33 showed promising activities

with IC50 values in the range of 5.5–5.8 mg mL�1, and MIC of

10 mg mL�1. These analogues were also fungicidal at 10 mg mL�1.

To conclude, the in vitro antimalarial activity data of the 8-

aminoquinolines reported herein clearly indicates a preference

for increased inhibition of the drug-resistant strain. This obser-

vation indicates the therapeutic potential of the reported 8-

aminoquinolines in the treatment of drug-resistant malaria

infections. None of the analogues showed cytotoxicity up to the

highest tested concentration providing evidence of their safety

profile. We have also observed potent in vivo blood-schizo-

ntocidal activities for these compounds in a drug-sensitive P.

berghei murine malaria model underlining their potential as

candidates for further studies. Several analogues also displayed

promising antileishmanial and moderate antimicrobial activities

providing proof of the untapped potential of this class of

This journal is ª The Royal Society of Chemistry 2011

compounds in the chemotherapy of diseases other than malaria.

It can be safely concluded that newly synthesized 8-amino-

quinolines exhibit a broad spectrum of activities against several

pathogenic protozoal and microbial infections, which will be

further explored to provide additional promising compounds

with improved biological activities.

Experimental

Melting points were recorded on a capillary melting point apparatus

and are uncorrected. The synthesized compounds were routinely

checked for their purity on pre-coated silica gel G254 TLC plates

(Merck) and the spots were visualized under UV spectrophotometer

and then by exposing them to iodine vapors. Column chromato-

graphic purification was carried out on Merck silica gel (100–200

mesh). IR spectra (lmax in cm�1) were recorded on a Nicolet FT-IR

Impact 410 instrument either using KBr pellets or in CH2Cl2.1H and

13C NMR spectra were recorded on a 300 MHz Bruker FT-NMR

(Avance DPX 300) spectrometer using tetramethylsilane as internal

standard and the chemical shifts are reported in d units. Mass spectra

were recorded on either HRMS (Finnigan Mat LCQ spectrometer)

(APCI/ESI) or Ultraflex Tof/Tof Bruker instrument (MALDI).

Elemental analyses were recorded on Elementar Vario EL spec-

trometer. The elemental analyses of all final compounds were within

�0.4% of the expected values, unless otherwise stated. All reagents

were purchased from Aldrich Chemicals Ltd.

General method for the synthesis of 2-[4-({4-[(6-methoxy-2/4,5-

substitutedquinolin-8-yl)amino]pentyl}amino)pentyl]-1H-

isoindole-1,3(2H)-diones (8–12), 2-(4-{[4-({4-[(6-methoxy-2/4,5-

substitutedquinolin-8-yl)amino]pentyl}amino)pentyl]amino}

pentyl)-1H-isoindole-1,3(2H)-diones (18–21), and 2-{4-[(4-{[4-

({4-[(6-methoxy-2/4,5-substitutedquinolin-8-yl)amino]pentyl}

amino)pentyl]amino}pentyl)amino]pentyl}-1H-isoindole-1,3(2H)-

diones (26–29)

A mixture of 8-aminoquinoline (1 or 3, or 5–7, or 13–17 or 22–25,

1 mmol), 2-(4-bromopentyl)-1,3-isoindolinedione (4.40 mmol)

and Et3N (4.40 mmol) was stirred at ambient temperature for 8 h.

EtOAc (20 mL) was added to the thick reaction mass, and the

Med. Chem. Commun., 2011, 2, 300–307 | 303

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MF

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IC50¼

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separated salt was filtered. The filtrate was concentrated and

residue was purified by column chromatography on silica gel

(100–200 mesh) using a mixture of CH3OH in CH2Cl2 to produce

8–12 or 18–21 or 26–29 as viscous oil.

2-[4-({4-[(6-methoxyquinolin-8-yl)amino]pentyl}amino)pentyl]-

1H-isoindole-1,3(2H)-dione (8). Yield: 68%; oil; IR (CH2Cl2):

3414, 1770, 1712 cm�1; 1H NMR (CDCl3): d 8.50 (d, 1H, J ¼ 4.4

Hz), 7.93 (d, 1H, J ¼ 8.5 Hz), 7.53 (m, 2H), 7.48 (m, 2H), 7.32

(dd, 1H, J¼ 4.4 and 8.5 Hz), 6.80 (bs, 1H), 6.62 (bs, 1H), 6.33 (d,

1H, J¼ 2.3 Hz), 6.28 (d, 1H, J¼ 2.3 Hz), 4.11 (t, 2H, J¼ 6.8 Hz),

3.87 (s, 3H), 3.66 (m, 1H), 3.46 (m, 3H), 1.78–1.64 (m, 8H), 1.33

(m, 6H); 13C NMR (CDCl3): d 169.4, 159.4, 144.8, 144.3, 135.3,

134.8, 134.6, 130.2, 129.9, 128.5, 121.8, 96.8, 61.7, 55.2, 50.2,

47.8, 40.1, 39.3, 38.1, 33.9, 27.8, 26.4, 20.6; MS (APCI): m/z 475

(M + 1).

2-[4-({4-[(2-tert-butyl-6-methoxyquinolin-8-yl)amino]pentyl}-

amino)pentyl]-1H-isoindole-1,3(2H)-dione (9). Yield: 77%; oil; IR

(CH2Cl2): 3407, 1722, 1709 cm�1; 1H NMR (CDCl3): d 7.86 (d,

1H, J¼ 8.5 Hz), 7.60–7.40 (m, 5H), 6.31 (d, 1H, J¼ 2.1 Hz), 6.26

(d, 1H, J¼ 2.1 Hz), 6.17 (bs, 2H), 4.10 (t, 2H, J¼ 5.6 Hz), 3.85 (s,

3H), 3.45 (m, 4H), 1.77–1.56 (m, 8H), 1.41 (s, 9H), 1.33 (m, 6H);13C NMR (CDCl3): d 169.6, 167.9, 167.8, 156.6, 145.3, 136.3,

135.4, 128.5, 127.6, 97.1, 91.3, 65.4, 55.3, 48.2, 38.8, 37.9, 35.4,

30.6, 29.0, 25.3, 21.3 MS (APCI): m/z 531 (M + 1).

2-[4-({4-[(5-butoxy-4-ethyl-6-methoxyquinolin-8-yl)amino]-

pentyl}amino)pentyl]-1H-isoindole-1,3(2H)-dione (10). Yield:

72%; oil; IR (CH2Cl2): 3373, 1774, 1714 cm�1; 1H NMR (CDCl3):

d 8.35 (d, 1H, J¼ 4.3 Hz), 7.58 (m, 4H), 7.12 (d, 1H, J¼ 4.3 Hz),

6.44 (s, 1H), 6.07 (bs, 1H), 4.12 (t, 2H, J ¼ 5.6 Hz), 3.94 (s, 3H),

3.90 (t, 2H, J ¼ 6.8 Hz), 3.66 (m, 1H), 3.44 (m, 3H), 3.27 (q, 2H,

J¼ 7.2 Hz), 1.83 (m, 10H), 1.70 (t, 3H, J¼ 7.2 Hz), 1.55 (m, 2H),

1.32 (m, 6H), 0.99 (t, 3H, J ¼ 7.3 Hz); 13C NMR (CDCl3):

d 168.3, 168.1, 150.0, 148.5, 143.3, 140.8, 133.5, 132.9, 129.0,

122.7, 122.6, 121.4, 93.4, 55.8, 49.9, 47.0, 39.2, 38.3, 37.1, 33.2,

28.6, 27.5, 26.7, 25.4, 21.5, 19.7, 14.5; MS (APCI): m/z 575

(M + 1).

2-{4-[(4-{[4-ethyl-6-methoxy-5-(pentyloxy)quinolin-8-yl]

amino}pentyl)amino]pentyl}-1H-isoindole-1,3(2H)-dione (11).

Yield: 72%; oil;IR (CH2Cl2): 3429, 1721, 1634 cm�1; 1H NMR

(CDCl3): d 8.35 (d, 1H, J ¼ 4.2 Hz), 7.59 (m, 4H), 7.12 (d, 1H,

J ¼ 4.2 Hz), 6.87 (bs, 2H), 6.44 (s, 1H), 6.07 (bs, 1H), 4.12 (t, 2H,

J ¼ 6.5 Hz), 3.94 (s, 3H), 3.89 (t, 2H, J ¼ 7.1 Hz), 3.67 (m, 1H),

3.45 (m, 3H), 3.27 (q, 2H, J ¼ 6.9 Hz), 1.85 (m, 17H), 1.44 (m,

6H), 0.96 (m, 3H); 13C NMR (CDCl3): d 169.6, 169.5, 144.9,

144.3, 138.6, 134.8, 129.9, 121.9, 96.8, 91.7, 55.2, 47.8, 39.5, 37.8,

34.0, 28.4, 27.9, 26.5, 20.6, 14.1; MS (APCI): m/z 589 (M + 1).

2-{4-[(4-{[4-ethyl-6-methoxy-5-(octyloxy)quinolin-8-yl]amino}-

pentyl)amino]pentyl}-1H-isoindole-1,3(2H)-dione (12). Yield:

62%; oil; IR (CH2Cl2): 3369, 1773, 1715 cm�1; 1H NMR (CDCl3):

d 8.36 (d, 1H, J ¼ 4.4 Hz), 7.61 (m, 5H), 7.14 (bs, 1H), 6.47 (s,

1H), 4.14 (t, 2H, J ¼ 5.7 Hz), 3.95 (s, 3H), 3.90 (t, 2H, J ¼ 6.8

Hz), 3.66 (m, 1H), 3.47 (m, 3H), 3.27 (q, 2H, J¼ 6.9 Hz), 1.85 (m,

20H), 1.33 (m, 9H), 0.96 (m, 3H); 13C NMR (CDCl3): d 169.3,

168.5, 147.5, 143.8, 141.8, 133.5, 133.9, 128.7, 123.7, 122.2, 98.6,

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93.4, 55.6, 48.9, 47.7, 38.7, 38.3, 36.4, 33.0, 27.6, 27.5, 26.8, 24.8,

21.6, 19.4, 14.2; MS (APCI): m/z 631 (M + 1).

2-(4-{[4-({4-[(6-methoxyquinolin-8-yl)amino]pentyl}amino)-

pentyl]amino}pentyl)-1H-isoindole-1,3(2H)-dione (18). Yield:

85%; oil; IR (CH2Cl2): 3414, 1722 cm�1; 1H NMR (CDCl3):

d 8.49 (d, 1H, J¼ 4.3 Hz), 7.93 (d, 1H, J¼ 8.1 Hz), 7.53–7.28 (m,

5H), 7.06 (bs, 1H), 6.91 (bs, 1H), 6.32 (s, 1H), 6.28 (s, 1H), 5.99

(bs, 1H), 4.10 (t, 2H, J ¼ 6.2 Hz), 3.87 (s, 3H), 3.64 (m, 1H), 3.41

(m, 6H), 1.75 (m, 12H), 1.32 (m, 9H); 13C NMR (CDCl3): d 169.9,

169.6, 159.9, 145.4, 144.8, 135.8, 135.3, 135.1, 134.9, 130.6, 130.4,

129.0, 128.7, 122.4, 97.3, 92.3, 55.7, 53.9, 51.5, 48.4, 40.7, 39.8,

38.7, 34.5, 30.2, 28.3, 27.0, 26.7, 21.; MS (MALDI): m/z 560 (M +

1).

2-(4-{[4-({4-[(2-tert-butyl-6-methoxyquinolin-8-yl)amino]pentyl}

amino)pentyl]amino}pentyl)-1H-isoindole-1,3(2H)-dione (19).

Yield: 84%; oil; IR (CH2Cl2): 3271, 1715, 1632 cm�1; 1H NMR

(CDCl3): d 7.89 (d, 1H, J ¼ 8.6 Hz), 7.50 (m, 5H), 6.96 (bs, 1H),

6.82 (bs, 1H), 6.35 (d, 1H, J ¼ 2.3 Hz), 6.30 (d, 1H, J ¼ 2.3 Hz),

5.65 (bs, 1H), 4.15 (t, 2H, J ¼ 6.6 Hz), 3.87 (s, 3H), 3.58 (m, 1H),

3.39 (m, 6H), 1.79 (m, 12H), 1.41 (s, 9H), 1.32 (m, 9H); 13C NMR

(CDCl3): d 167.9, 164.8, 159.9, 145.4, 144.6, 136.7, 135.1, 133.9,

132.5, 131.3, 130.4, 129.6, 128.1, 121.6, 97.8, 92.1, 55.7, 53.4,

51.9, 47.4, 39.8, 38.7, 33.5, 30.6, 29.1, 26.5, 26.1, 21.6; MS

(MALDI): m/z 617 (M + 1).

2-(4-{[4-({4-[(5-butoxy-4-ethyl-6-methoxyquinolin-8-yl)amino]

pentyl}amino)pentyl]amino}pentyl)-1H-isoindole-1,3(2H)-dione

(20). Yield: 78%; oil; IR (CH2Cl2): 3419, 1773, 1714 cm�1; 1H

NMR (CDCl3): d 8.35 (d, 1H, J ¼ 4.3 Hz), 7.60 (m, 4H), 7.12 (d,

1H, J ¼ 4.3 Hz), 6.79 (bs, 2H), 6.44 (s, 1H), 6.08 (bs, 2H), 4.11 (t,

2H, J ¼ 5.8 Hz), 3.94 (s, 3H), 3.90 (t, 2H, J ¼ 7.4 Hz), 3.67 (m,

1H), 3.46 (m, 6H), 3.27 (q, 2H, J ¼ 7.3 Hz), 1.85 (m, 19H), 1.32

(m, 9H), 1.02 (t, 3H, J ¼ 7.3 Hz); 13C NMR (CDCl3): d 168.3,

168.1, 150.0, 148.5, 143.3, 140.8, 133.5, 132.9, 129.0, 122.7, 122.6,

121.4, 93.4, 55.8, 49.9, 47.0, 39.2, 38.3, 37.1, 33.2, 28.6, 27.5, 26.7,

25.4, 21.5, 19.7, 14.5; MS (MALDI): m/z 660 (M + 1).

2-[4-({4-[(4-{[4-ethyl-6-methoxy-5-(pentyloxy)quinolin-8-yl]-

amino}pentyl)amino]pentyl}amino)pentyl]-1H-isoindole-1,3(2H)-dione

(21). Yield: 81%; oil; IR (CH2Cl2): 3424, 1641 cm�1; 1H NMR

(CDCl3): d 8.35 (d, 1H, J ¼ 4.3 Hz), 7.59 (m, 4H), 7.12 (d, 1H, J

¼ 4.3 Hz), 6.83 (bs, 1H), 6.44 (s, 1H), 4.13 (t, 2H, J ¼ 5.9 Hz),

3.94 (s, 3H), 3.89 (t, 2H, J ¼ 6.9 Hz), 3.66 (m, 1H), 3.45 (m, 6H),

3.27 (q, 2H, J¼ 7.3 Hz), 1.85 (m, 21H), 1.41 (m, 9H), 0.97 (t, 3H,

J ¼ 6.9 Hz); 13C NMR (CDCl3): d 169.4, 169.1, 134.6, 132.4,

130.2, 128.5, 128.1, 123.7, 122.4, 56.8, 50.9, 48.1, 40.2, 39.3, 38.1,

34.2, 29.6, 28.5, 28.2, 27.7, 26.4, 26.1, 22.5, 20.7, 15.5; MS

(APCI): m/z 674 (M + 1).

2-{4-[(4-{[4-({4-[(6-methoxyquinolin-8-yl)amino]pentyl}amino)-

pentyl]amino}pentyl)amino]pentyl}-1H-isoindole-1,3(2H)-dione

(26). Yield: 94%; oil; IR (CH2Cl2): 3387, 1732 cm�1; 1H NMR

(CDCl3): d 8.50 (d, 1H, J¼ 4.2 Hz), 7.93 (d, 1H, J¼ 8.2 Hz), 7.60

(d, 2H, J¼ 7.3 Hz), 7.51 (d, 2H, J¼ 7.3 Hz), 7.31 (dd, J¼ 4.2 and

8.2 Hz), 6.88 (bs, 1H), 6.71 (bs, 1H), 7.31 (dd, 1H, J¼ 4.2 and 8.2

Hz), 6.33 (d, 1H, J ¼ 2.2 Hz), 6.28 (d, 1H, J ¼ 2.2 Hz), 6.02 (bs,

2H), 4.11 (t, 2H, J ¼ 6.5 Hz), 3.87 (s, 3H), 3.65 (m, 1H), 3.44 (m,

This journal is ª The Royal Society of Chemistry 2011

9H), 1.77 (m, 16H), 1.32 (m, 12H); 13C NMR (CDCl3): d 169.9,

169.7, 159.9, 145.4, 144.8, 135.8, 135.3, 134.9, 131.4, 130.5, 129.0,

128.7, 122.4, 97.3, 92.3, 55.7, 54.0, 51.5, 48.4, 40.6, 39.8, 38.7,

34.5, 30.9, 28.2, 27.0, 24.2, 21.1; MS (APCI): m/z 645 (M + 1).

2-{4-[(4-{[4-({4-[(2-tert-butyl-6-methoxyquinolin-8-yl)amino]-

pentyl}amino)pentyl]amino}pentyl)amino]pentyl}-1H-isoindole-

1,3(2H)-dione (27). Yield: 88%; oil; IR (CH2Cl2): 3270, 1709,

1632 cm�1; 1H NMR (CDCl3): d 7.85 (d, 1H, J¼ 8.6 Hz), 7.51 (d,

2H, J ¼ 6.6 Hz), 7.42 (m, 3H), 7.19 (bs, 1H), 7.01 (bs, 1H), 6.29

(s, 1H), 6.26 (s, 1H), 6.14 (bs, 2H), 4.09 (t, 2H, J ¼ 6.0 Hz), 3.84

(s, 3H), 3.61 (m, 1H), 3.40 (m, 9H), 1.75 (m, 16H), 1.41 (s, 9H),

1.32 (m, 12H); 13C NMR (CDCl3): d 169.9, 169.6, 163.8, 159.3,

145.4, 135.5, 135.0, 134.9, 134.1, 133.1, 130.5, 129.0, 128.7, 128.0,

126.2, 123.9, 119.3, 97.2, 92.1, 55.7, 50.7, 48.4, 40.7, 39.8, 38.7,

38.2, 34.6, 31.3, 30.8, 30.2, 28.9, 27.0, 26.6, 24.0, 21.2; MS

(MALDI): m/z 702 (M + 1).

2-{4-[(4-{[4-({4-[(5-butoxy-4-ethyl-6-methoxyquinolin-8-yl)

amino]pentyl}amino)pentyl]amino}pentyl)amino]pentyl}-1H-

isoindole-1,3(2H)-dione (28). Yield: 89%; oil; IR (CH2Cl2): 3435,

1635 cm�1; 1H NMR (CDCl3): d 8.35 (d, 1H, J¼ 4.3 Hz), 7.58 (m,

4H), 7.12 (d, 1H, J¼ 4.3 Hz), 6.91 (bs, 3H), 6.44 (s, 1H), 6.07 (bs,

1H), 4.13 (t, 2H, J ¼ 5.8 Hz), 3.94 (s, 3H), 3.90 (t, 2H, J ¼ 6.8

Hz), 3.67 (m, 1H), 3.44 (m, 8H), 3.27 (q, 2H, J¼ 7.3 Hz), 1.85 (m,

23H), 1.32 (m, 12H), 1.02 (t, 3H, J¼ 7.3 Hz); 13C NMR (CDCl3):

d 168.3, 168.1, 150.0, 148.5, 143.3, 140.8, 133.6, 132.9, 131.3,

129.1, 127.4, 127.1, 122.6, 121.4, 93.4, 55.8, 49.9, 47.0, 39.2, 38.3,

37.1, 27.5, 26.7, 25.4, 25.1, 19.7, 18.2, 14.5; MS (MALDI): m/z

746 (M + 2).

2-(4-{[4-({4-[(4-{[4-ethyl-6-methoxy-5-(pentyloxy)quinolin-

8-yl]amino}pentyl)amino]pentyl}amino)pentyl]amino}pentyl)-1H-

isoindole-1,3(2H)-dione (29). Yield: 92%; oil; IR (CH2Cl2): 3272,

1718, 1631 cm�1; 1H NMR (CDCl3): d 8.28 (d, 1H, J ¼ 4.3 Hz),

7.48 (m, 4H), 7.04 (d, 1H, J¼ 4.3 Hz), 6.93 (bs, 1H), 6.36 (s, 1H),

4.05 (t, 2H, J ¼ 5.8 Hz), 3.87 (s, 3H), 3.82 (t, 2H, J ¼ 6.9 Hz),

3.59–3.53 (m, 10H), 3.20 (q, 2H, J ¼ 7.3 Hz), 1.78 (m, 25H), 1.37

(m, 12H), 0.89 (t, 3H, J ¼ 6.9 Hz); 13C NMR (CDCl3): d 168.3,

168.1, 150.0, 148.5, 143.3, 140.8, 133.5, 132.9, 129.0, 122.6, 93.4,

73.1, 55.8, 49.9, 39.2, 38.3, 37.1, 33.2, 28.6, 27.5, 27.2, 26.7, 25.4,

21.5, 19.7, 14.5; MS (MALDI): m/z 759 (M + 1).

General method for the synthesis of 1,4-diamines 13–17, 22–25,

and 30–33

To a solution of 8–12 or 18–21 or 26–29 (0.26 mmol) in 95%

ethanol (15 mL), was added NH2NH2$H2O (6.60 mmol) and the

reaction mixture was stirred with refluxing for 6 h. The solvent

was removed under reduced pressure. The residue was diluted

with water (20 mL) and extracted with CH2Cl2 (3 � 20 mL). The

organic layer washed with brine solution (10 mL), dried over

Na2SO4 and concentrated to yield 13–17, 22–25, and 30–33 as oil,

which upon treatment with 2 N ethereal HCl solution provided

their dihydrochloride salts.

N1-(5-aminopentan-2-yl)-N4-(6-methoxyquinolin-8-yl)pentane-

1,4-diamine$2HCl (13). Yield: 82%; hygroscopic solid; IR (free

base, CH2Cl2): 3361 cm�1; 1H NMR (free base, CDCl3): d 8.53 (d,

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1H, J ¼ 4.0 Hz), 7.93 (d, 1H, J ¼ 8.0 Hz), 7.32 (dd, 1H, J ¼ 4.0

and 8.0 Hz), 6.78 (bs, 1H), 6.56 (bs, 1H), 6.33 (d, 1H, J¼ 2.2 Hz),

6.28 (d, 1H, J¼ 2.2 Hz), 5.45 (bs, 2H), 3.89 (s, 3H), 3.62 (m, 1H),

2.76 (m, 5H), 2.04–1.82 (m, 4H), 1.74–1.64 (m, 4H), 1.31 (m, 6H);13C NMR (free base, CDCl3): d 156.9, 144.8, 135.3, 130.4, 122.4,

97.3, 92.2, 55.7, 53.8, 48.3, 39.9, 34.4, 30.7, 28.9, 27.0, 24.0, 21.1;

MS (APCI): m/z 346 (M + 2).

N1-(5-aminopentan-2-yl)-N4-(2-tert-butyl-6-methoxyquinolin-8-

yl)pentane-1,4-diamine$2HCl (14). Yield: 86%; hygroscopic solid;

IR (free base, CH2Cl2): 3380 cm�1; 1H NMR (free base, CDCl3):

d 7.86 (d, 1H, J¼ 8.5 Hz), 7.42 (d, 1H, J¼ 8.5 Hz), 6.77 (bs, 2H),

6.30 (d, 1H, J ¼ 1.9 Hz), 6.26 (d, 1H, J ¼ 1.9 Hz), 6.17 (bs, 2H),

3.86 (s, 3H), 3.57 (m, 1H), 2.76 (m, 5H), 2.04 (m, 4H), 1.72–1.62

(m, 4H), 1.42 (s, 9H), 1.31 (m, 6H); 13C NMR (free base, CDCl3):

d 163.8, 159.4, 145.5, 135.5, 134.2, 128.0, 119.2, 97.0, 91.9, 55.7,

48.6, 42.7, 38.2, 34.7, 30.8, 30.7, 30.2, 21.2; MS (APCI): m/z 401

(M + 1).

N1-(5-aminopentan-2-yl)-N4-(5-butoxy-4-ethyl-6-methoxy-

quinolin-8-yl)pentane-1,4-diamine$2HCl (15). Yield: 84%;

hygroscopic solid; IR (free base, CH2Cl2): 3436 cm�1; 1H NMR

(free base, CDCl3): d 8.40 (d, 1H, J¼ 4.3 Hz), 7.12 (d, 1H, J¼ 4.3

Hz), 6.44 (s, 1H), 3.96 (s, 3H), 3.91 (t, 2H, J ¼ 6.8 Hz), 3.63 (m,

1H), 3.27 (q, 2H, J ¼ 7.3 Hz), 2.75 (m, 5H), 1.86 (m, 15H), 1.32

(m, 6H), 0.99 (t, 3H, J ¼ 7.3 Hz); 13C NMR (free base, CDCl3):

d 151.6, 150.0, 144.8, 142.6, 134.5, 132.7, 124.2, 122.9, 94.8, 74.4,

57.3, 48.7, 42.8, 34.8, 30.8, 29.1, 24.0, 21.2, 19.8, 16.0; MS

(APCI): m/z 445 (M + 1).

N1-(5-aminopentan-2-yl)-N4-[4-ethyl-6-methoxy-5-(pentyloxy)-

quinolin-8-yl]pentane-1,4-diamine$2HCl (16). Yield: 90%; hygro-

scopic solid; IR (free base, CH2Cl2): 3392 cm�1; 1H NMR (free

base, CDCl3): d 8.40 (d, 1H, J¼ 4.3 Hz), 7.12 (d, 1H, J¼ 4.3 Hz),

6.44 (s, 1H), 5.98 (bs, 2H), 3.96 (s, 3H), 3.91 (t, 2H, J ¼ 6.8 Hz),

3.63 (m, 1H), 3.27 (q, 2H, J ¼ 7.3 Hz), 2.75 (m, 5H), 1.86 (m,

17H), 1.32 (m, 6H), 0.99 (t, 3H, J¼ 7.3 Hz); 13C NMR (free base,

CDCl3): d 159.4, 144.9, 144.3, 135.3, 134.9, 129.9, 121.8, 96.8,

91.7, 53.2, 47.8, 40.3, 31.3, 28.3, 26.8, 20.5, 16.2, 14.1; MS

(APCI): m/z 459 (M + 1).

N1-(5-aminopentan-2-yl)-N4-[4-ethyl-6-methoxy-5-(octyloxy)-

quinolin-8-yl]pentane-1,4-diamine$2HCl (17). Yield: 54%; hygro-

scopic solid; IR (free base, CH2Cl2): 3418 cm�1; 1H NMR (free

base, CDCl3): d 8.32 (d, 1H, J¼ 4.2 Hz), 7.05 (d, 1H, J¼ 4.2 Hz),

6.40 (s, 1H), 3.89 (s, 3H), 3.82 (t, 2H, J ¼ 6.5 Hz), 3.59 (m, 1H),

3.18 (q, 2H, J ¼ 5.0 Hz), 2.73 (m, 5H), 1.96 (m, 20H), 1.25 (m,

9H), 0.93 (t, 3H, J ¼ 5.0 Hz); 13C NMR (free base, CDCl3):

d 159.6, 144.8, 135.3, 130.4, 122.4, 97.3, 92.4, 55.7, 53.8, 48.3,

39.9, 34.5, 30.8, 28.9, 27.0, 20.0, 15.3; MS (APCI): m/z 501 (M +

1).

N-(5-aminopentan-2-yl)-N0-{4-[(6-methoxyquinolin-8-yl)amino]

pentyl}pentane-1,4-diamine$2HCl (22). Yield: 68%; hygroscopic

solid; IR (free base, CH2Cl2): 3393 cm�1; 1H NMR (free base,

CDCl3): d 8.53 (dd, 1H, J¼ 1.4 and 4.0 Hz), 7.93 (dd, 1H, J¼ 1.4

and 8.1 Hz), 7.31 (dd, 1H, J ¼ 4.0 and 8.0 Hz), 6.33 (d, 1H, J ¼2.3 Hz), 6.28 (d, 1H, J¼ 2.3 Hz), 6.02 (bs, 2H), 5.78 (bs, 2H), 3.89

(s, 3H), 3.61 (m, 1H), 2.74 (m, 8H), 1.74 (m, 12H), 1.30 (m, 9H);

306 | Med. Chem. Commun., 2011, 2, 300–307

13C NMR (free base, CDCl3): d 158.4, 144.0, 143.2, 134.3, 133.7,

128.8, 120.7, 95.6, 90.5, 54.1, 46.9, 41.2, 33.0, 30.8, 30.6, 29.3,

28.6, 28.4, 28.3, 21.6, 19.5; MS (APCI): m/z 429.7.

N-(5-aminopentan-2-yl)-N 0-{4-[(2-tert-butyl-6-methoxy-

quinolin-8-yl)amino]pentyl}pentane-1,4-diamine$2HCl (23).

Yield: 63%; hygroscopic solid; IR (free base, CH2Cl2): 3370 cm�1;1H NMR (free base, CDCl3): d 7.86 (d, 1H, J ¼ 8.6 Hz), 7.43 (d,

1H, J ¼ 8.6 Hz), 6.31 (d, 1H, J ¼ 2.3 Hz), 6.26 (d, 1H, J ¼ 2.3

Hz), 6.16 (bs, 1H), 5.89 (bs, 2H), 3.87 (s, 3H), 3.62 (m, 1H), 2.76

(m, 8H), 2.31 (bs, 2H), 1.68 (m, 12H), 1.42 (s, 9H), 1.32 (m, 9H, 2

� CH3); 13C NMR (free base, CDCl3): d 162.2, 157.8, 144.0,

133.9, 132.6, 126.4, 117.7, 95.4, 90.3, 54.1, 47.0, 41.1, 36.6, 33.1,

29.2, 29.0, 28.6, 24.2, 22.7, 19.6; MS (MALDI): m/z 485 (M + 1).

N-(5-aminopentan-2-yl)-N0-{4-[(5-butoxy-4-ethyl-6-methoxy-

quinolin-8-yl)amino]pentyl}pentane-1,4-diamine$2HCl (24).

Yield: 64%; hygroscopic solid; IR (free base, CH2Cl2): 3436 cm�1;1H NMR (free base, CDCl3): d 8.40 (d, 1H, J ¼ 4.3 Hz), 7.12 (d,

1H, J ¼ 4.3 Hz), 6.44 (s, 1H), 3.96 (s, 3H), 3.91 (t, 2H, J ¼ 6.8

Hz), 3.63 (m, 1H), 3.27 (q, 2H, J¼ 7.3 Hz), 2.76 (m, 8H), 1.81 (m,

19H), 1.32 (m, 9H), 1.01 (t, 3H, J¼ 7.2 Hz); 13C NMR (free base,

CDCl3): d 151.1, 149.5, 144.3, 142.0, 134.0, 132.2, 123.6, 122.4,

94.3, 73.6, 56.8, 48.2, 42.2, 34.2, 32.1, 30.2, 29.6, 28.5, 23.4, 20.7,

19.2, 15.5, 13.9; MS (APCI): m/z 531 (M + 2).

N-(5-aminopentan-2-yl)-N0-(4-{[4-ethyl-6-methoxy-5-(pentyl-

oxy)quinolin-8-yl]amino}pentyl)pentane-1,4-diamine$2HCl (25).

Yield: 67%; hygroscopic solid; IR (free base, CH2Cl2): 3430 cm�1;1H NMR (free base, CDCl3): d 8.40 (d, 1H, J ¼ 4.3 Hz), 7.12 (d,

1H, J ¼ 4.3 Hz), 6.44 (s, 1H), 3.96 (s, 3H), 3.90 (t, 2H, J ¼ 6.8

Hz), 3.63 (m, 1H), 3.27 (q, 2H, J¼ 7.3 Hz), 2.76 (m, 8H), 1.85 (m,

21H), 1.32 (m, 9H), 0.99 (t, 3H, J¼ 6.9 Hz); 13C NMR (free base,

CDCl3): d 151.1, 149.5, 144.3, 142.0, 134.0, 132.2, 123.6, 122.4,

94.3, 74.2, 56.8, 48.2, 42.2, 34.2, 30.2, 29.6, 28.5, 24.0, 22.5, 20.7,

15.5, 14.0; MS (MALDI): m/z 544 (M + 1).

N-(5-aminopentan-2-yl)-N0-[4-({4-[(6-methoxyquinolin-8-yl)-

amino]pentyl}amino)pentyl]pentane-1,4-diamine$2HCl (30).

Yield: 61%; hygroscopic solid; IR (free base, CH2Cl2): 3419 cm�1;1H NMR (free base, CDCl3): d 8.53 (dd, 1H, J¼ 1.5 and 4.1 Hz),

7.93 (dd, 1H, J ¼ 1.5 and 8.2 Hz), 7.31 (dd, 1H, J ¼ 4.1 and 8.2

Hz), 6.86 (bs, 1H), 6.57 (bs, 1H), 6.33 (d, 1H, J¼ 2.3 Hz), 6.28 (d,

1H, J¼ 2.3 Hz), 6.02 (bs, 2H), 3.89 (s, 3H), 3.62 (m, 1H), 3.48 (m,

9H), 2.74 (t, 2H, J ¼ 5.3 Hz), 1.76 (m, 16H), 1.32 (m, 12H); 13C

NMR (free base, CDCl3): d 160.0, 145.6, 144.8, 135.9, 135.3,

131.4, 130.4, 122.3, 97.1, 92.1, 55.7, 48.5, 42.8, 34.6, 31.4, 30.9,

30.2, 25.5, 24.3, 21.1; MS (APCI): m/z 516 (M + 2).

N-(5-aminopentan-2-yl)-N0-[4-({4-[(2-tert-butyl-6-methoxy-

quinolin-8-yl)amino]pentyl}amino)pentyl]pentane-1,4-diamine$

2HCl (31). Yield: 61%; hygroscopic solid; IR (free base, CH2Cl2):

3370 cm�1; 1H NMR (free base, CDCl3): d 7.82 (d, 1H, J ¼ 8.4

Hz), 7.34 (d, 1H, J¼ 8.4 Hz), 7.02 (bs, 1H), 6.98 (bs, 1H), 6.35 (d,

1H, J ¼ 2.1 Hz), 6.24 (d, 1H, J ¼ 2.1 Hz), 5.87 (bs, 2H), 3.85 (s,

3H), 3.59 (m, 1H), 3.25–2.71 (m, 11H), 1.73 (m, 16H), 1.42 (s,

9H), 1.35 (m, 12H); 13C NMR (free base, CDCl3): d 164.8, 160.0,

144.6, 135.4, 133.8, 131.4, 128.4, 117.6, 97.5, 93.4, 55.8, 47.5,

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41.5, 35.1, 32.4, 31.2, 26.5, 23.8, 21.6; MS (MALDI): m/z 572

(M + 2).

N-(5-aminopentan-2-yl)-N 0-{4-[(4-{[5-butoxy-4-ethyl-6-

methoxyquinolin-8-yl]amino}pentyl)amino]pentyl}pentane-1,4-

diamine$2HCl (32). Yield: 62%; hygroscopic solid; IR (free base,

CH2Cl2): 3429 cm�1; 1H NMR (free base, CDCl3): d 8.40 (d, 1H,

J ¼ 4.3 Hz), 7.12 (d, 1H, J ¼ 4.3 Hz), 6.41 (s, 1H), 6.09 (bs, 1H),

3.96 (s, 3H), 3.91 (t, 2H, J ¼ 6.8 Hz), 3.63 (m, 1H), 3.27 (q, 2H,

J ¼ 7.3 Hz), 2.75 (m, 11H), 1.81 (m, 23H), 1.32 (m, 12H), 1.01 (t,

3H, J ¼ 7.3 Hz); 13C NMR (free base, CDCl3): d 151.6, 150.0,

144.8, 142.6, 134.5, 132.7, 124.2, 122.9, 94.7, 74.8, 57.3, 48.7,

42.8, 34.8, 32.6, 30.9, 29.1, 21.2, 19.8, 16.0; MS (MALDI): m/z

615 (M + 1).

N-(5-aminopentan-2-yl)-N0-{4-[(4-{[4-ethyl-6-methoxy-5-(pen-

tyloxy)quinolin-8-yl]amino}pentyl)amino]pentyl}pentane-1,4-dia-

mine$2HCl (33). Yield: 61%; hygroscopic solid; IR (free base,

CH2Cl2): 3400 cm�1; 1H NMR (free base, CDCl3): d 8.40 (d, 1H,

J ¼ 4.3 Hz), 7.12 (d, 1H, J ¼ 4.3 Hz), 6.44 (s, 1H), 6.09 (bs, 1H),

3.96 (s, 3H), 3.90 (t, 2H, J ¼ 6.9 Hz), 3.62 (m, 1H), 3.27 (q, 2H,

J ¼ 7.3 Hz), 2.75 (m, 11H), 1.80 (m, 25H), 1.39 (m, 12H), 0.96 (t,

3H, CH3); 13C NMR (free base, CDCl3): d 151.6, 150.0, 144.8,

142.6, 134.5, 132.7, 122.9, 94.7, 74.7, 57.3, 48.7, 42.8, 34.8, 31.0,

29.1, 28.7, 23.1, 21.2, 16.0, 14.6; MS (MALDI): m/z 630 (M + 2).

Acknowledgements

Kirandeep Kaur thanks the Council of Scientific and Industrial

Research (CSIR), New Delhi for the award of Senior Research

Fellowship. Antimicrobial testing was supported by the NIH,

NIAID, Division of AIDS, Grant No. AI 27094. Support from

the USDA Agricultural Research Service Specific Cooperative

Agreement No. 58-6408-2-0009 is also acknowledged in the in

vitro screening of antimicrobial, antiprotozoal, and cytotoxic

activity.

References

1 B. L. Tekwani and L. A. Walker, Curr. Opin. Infect. Dis., 2006, 19,623–631.

2 G. W. Mihaly, S. A. Ward, G. Edwards, M. L. E. Orme andA. M. Breckenridge, Br. J. Clin. Pharmacol, 1984, 17, 441–446.

3 J. K. Baker, J. A. Bedford, A. M. Clark and J. D. McChesney, Pharm.Res., 1984, 1, 98–100.

4 J. K. Baker, R. H. Yarber, N. P. D. Nanayakkara, J. D. Mc Chesney,F. Homo and I. Landau, Pharm. Res., 1990, 7, 91–95.

5 L. Constantino, P. Paixao, R. Moreira, M. J. Portela, V. E. J. Ros�arioand J. Iley, Exp. Toxicol. Pathol, 1999, 51, 299–303.

6 S. Ganesan, B. L. Tekwani, R. Sahu, L. M. Tripathi andL. A. Walker, Toxicol. Appl. Pharmacol., 2009, 241, 14–22.

This journal is ª The Royal Society of Chemistry 2011

7 A. Philip, J. A. Kepler, B. H. Johnson and F. Y. Carroll, J. Med.Chem., 1988, 31, 870–874.

8 R. Borissova, P. Stjarnkvist, M. O. Karlsson and I. Sjoholm, J.Pharm. Sci., 1995, 84, 256–262.

9 M. C. Chung, M. F. Goncalves, W. Colli, E. I. Ferreira andM. T. M. Miranda, J. Pharm. Sci., 1997, 86, 1127–1132.

10 M. J. Portela, R. Moreira, E. Valente, L. Constantino, J. Iley, J. Pinto,R. Rosa, P. Cravo and V. E. Ros�ario, Pharm. Res., 1999, 16, 949–955.

11 T. J. Egan, R. Hunter, C. H. Kaschula, H. M. Marques, A. Misplonand J. Walden, J. Med. Chem., 2000, 43, 283–291.

12 S. Vangapandu, S. Sachdeva, M. Jain, S. Singh, P. P. Singh,C. L. Kaul and R. Jain, Bioorg. Med. Chem., 2004, 12, 239–247.

13 N. T. Huy, K. Mizunuma, K. Kaur, N. T. T. Nhien, M. Jain,D. H. Uyen, S. Harada, R. Jain and K. Kamei, Antimicrob. AgentsChemother., 2007, 51, 2842–2847.

14 J. L. Vennerstrom, E. O. Nuzum, R. E. Miller, A. Dorn, L. Gerena,P. A. Dande, W. Y. Ellis, R. G. Ridley and W. K. Milhous,Antimicrob. Agents Chemother., 1999, 43, 598–602.

15 B. L. Tekwani and L. A. Walker, Comb. Chem. High ThroughputScreening, 2005, 8, 63–79.

16 P. M. O’Neill, A. Mukhtar, P. A. Stocks, L. E. Randle, S. Hindley,S. A. Ward, R. C. Storr, J. F. Bickley, I. A. O’Neil, J. L. Maggs,R. H. Hughes, P. A. Winstanley, P. G. Bray and B. K. Park, J.Med. Chem., 2003, 46, 4933–4945.

17 P. M. O’Neill, A. E. Shone, D. Stanford, G. Nixon, E. Asadollahy,B. K. Park, J. L. Maggs, P. Roberts, P. A. Stocks, G. Biagini,P. G. Bray, J. Davies, N. Berry, C. Hall, K. Rimmer,P. A. Winstanley, S. Hindley, R. B. Bambal, C. B. Davis, M. Bates,S. L. Gresham, R. A. Brigandi, F. M. Gomez-de-las-Heras,D. V. Gargallo, S. Parapini, L. Vivas, H. Lander, D. Taramelli andS. A. Ward, J. Med. Chem., 2009, 52, 1828–1844.

18 M. A. L. Blackie, P. Beagley, S. L. Croft, H. Kendrick, J. R. Mossaand K. Chibale, Bioorg. Med. Chem., 2007, 15, 6510–6516.

19 M. T. Makler and D. J. Hinrichs, Am. J. Trop. Med. Hyg., 1993, 48,205–210.

20 M. Jain, S. Vangapandu, S. Sachdeva, S. Singh, P. P. Singh,G. B. Gena, K. Tikoo, P. Ramarao, C. L. Kaul and R. Jain, J.Med. Chem., 2004, 47, 285–287.

21 E. Borenfreund, H. Babich and N. Martin-Alguacil, In Vitro Cell.Dev. Biol., 1990, 26, 1030–1034.

22 J. Mustafa, S. I. Khan, G. Ma, L. A. Walker and I. A. Khan, Lipids,2004, 39, 167–172.

23 J. Mikus and D. Steverding, Parasitol. Int., 2000, 48, 265–269.24 G. Ma, S. I. Khan, M. R. Jacob, B. L. Tekwani, Z. Li, D. S. Pasco,

L. A. Walker and I. A. Khan, Antimicrob. Agents Chemother., 2004,48, 4450–4452.

25 NCCLS, Methods for dilution antimicrobial susceptibility tests forbacteria that grow aerobically M7-A5. National Committee onClinical Laboratory Standards, 2000, 20.

26 NCCLS, Reference method for broth dilution antifungal susceptibilitytesting of yeasts approved standard M27-A2. National Committee onClinical Laboratory Standards, 2002, 22.

27 NCCLS, Reference method for broth dilution antifungal susceptibilitytesting of filamentous fungi approved standard, M38-A. NationalCommittee on Clinical Laboratory Standards, 2002, 22.

28 NCCLS, Susceptibility testing of Mycobacteria, Nocardia, and otheraerobic Actinomycetes Tentative Standard-Second Edition, M24-T2.National Committee on Clinical Laboratory Standards, 2000, 20.

29 S. G. Franzblau, R. S. Witzig, J. C. McLaughlin, P. Torres,G. Madico, A. Hernandez, M. T. Degnan, M. B. Cook,V. K. Quenzer, R. M. Ferguson and R. H. Gilman, J. Clin.Microbiol., 1998, 36, 362–366.

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