Synthesis and radioiodination of some 9-aminoacridine derivatives for potential use in radionuclide therapy

Article abstract of DOI:10.1002/jlcr.960

Three derivatives of the DNA intercalating compound 9-aminoacridine, were prepared and radioiodinated for biological experiments. The compounds are the stannyl derivatives 3-{4-[3-(acridin-9-ylamino)-propoxy]-3-trimethylstannyl- phenyl}-propionic acid and acridin-9-yl-{3-[4-(2-amino-ethyl)-2- trimethylstannyl-phenoxy]-propyl}-amine which were synthesized from the corresponding iodo derivatives by palladium catalyzed reactions, and 4-[2-(acridin-9-ylamino)-ethyl]-phenol. The two stannylated compounds and the phenol were used as precursors for radioiodination and were labeled with ¹²⁵I using chloramine-T as an oxidant achieving high-to-excellent yields. Copyright

Full text of DOI:10.1002/jlcr.960

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS
J Label Compd Radiopharm 2005; 48: 855–871.
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jlcr.960
Research Article
Synthesis and radioiodination of some 9-aminoacridine
derivatives for potential use in radionuclide therapy
Senait Ghirmai1, Eskender Mume1, Hans Lundqvist2, Vladimir Tolmachev1,2
and Stefan Sjoberg1,*
¨
1 Department of Chemistry, Organic Chemistry, Uppsala University, Box 599, BMC,
S-751 24 Uppsala, Sweden
2 Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala University, S-751 85,
Uppsala, Sweden
Summary
Three derivatives of the DNA intercalating compound 9-aminoacridine, were
prepared and radioiodinated for biological experiments. The compounds are the
stannyl derivatives 3-{4-[3-(acridin-9-ylamino)-propoxy]-3-trimethylstannyl-phenyl}-
propionic acid and acridin-9-yl-{3-[4-(2-amino-ethyl)-2-trimethylstannyl-phenoxy]-
propyl}-amine which were synthesized from the corresponding iodo derivatives by
palladium catalyzed reactions, and 4-[2-(acridin-9-ylamino)-ethyl]-phenol. The two
stannylated compounds and the phenol were used as precursors for radioiodination
and were labeled with 125I using chloramine-T as an oxidant achieving high-to-
excellent yields. Copyright # 2005 John Wiley & Sons, Ltd.
Key Words: 9-aminoacridine derivatives; radioiodination; chloramine-T; 125I
Introduction
Acridine derivatives are among the most highly explored biologically active
agents. Their biological stability and ability to bind efficiently to DNA are
among the properties that could potentially make them useful anti-cancer
agents.1,2 It is believed that acridines bind to DNA by intercalation into the
helix by extension of the backbone.3,4 Intercalation of acridines was shown to
increase by amino-group substitution at position 9.5 Thus, several 9-
aminoacridine derivatives have been synthesized and demonstrated to have
high anti-tumor activity.6–8
*Correspondence to: S. Sjoberg, Department of Chemistry, Organic Chemistry, Uppsala University, Box
¨
599, S-751 24 Uppsala, Sweden. E-mail: ssj@kemi.uu.se
Contract/grant sponsor: Swedish Cancer Foundation
Contract/grant sponsor: INTAS; contract/grant number: 99-00806
Copyright # 2005 John Wiley & Sons, Ltd.
Received 28 February 2005
Revised 24 April 2005
Accepted 25 April 2005

856
S. GHIRMAI ET AL.
O
R
(CH2)n
(CH2)2CO2H
R =
n = 2 ,
HN
N
X
X = H
2a:
X = I or 125I
2b or *2b:
1
X = Sn(CH3)3
2c:
n = 3 ,
O
(CH2)2NH2
R =
OH
n = 2,
R =
X
X
3a:
X = H
4a:
X = H
X = I or 125
I
3b or *3b:
4b or *4b: X = I or 125I
4c:
X = Sn(CH3)3
Figure 1. The 9-aminoacridine derivatives synthesized
The anti-tumor activity of the 9-aminoacridines is further enhanced by
attachment of Auger electron-emitting radionuclides, such as 125I. The short
range of Auger electrons makes it possible to limit the biological effect of
radiation on cells, where decay happens, sparing surrounding healthy tissues.
On the other hand, since Auger electrons only travel a short distance, the
compound containing the radionuclide has to be delivered to the nucleus of the
tumor cell to effect total eradication of the cell.
The concept of ‘two step targeting’9–11 was introduced in our research group
to ensure specific delivery of drugs to the cell nucleus. The first targeting step
includes the specific delivery of DNA intercalating compounds to cancer cells
and their internalization into the cytoplasm. Sterically stablized liposomes
with polyethylene glycol are employed as drug transport vesicles at this step.
In order to achieve higher specific delivery of the drug to the tumor cells, the
liposomes are conjugated to targeting proteins or peptides such as epidermal
growth factor (EGF), since their receptors are known to be overexpressed in
some tumor cells compared to normal cells. In the second step, an Auger
electron-emitting radionuclide, directed by its DNA intercalating part, enters
into the nucleus and destroys the DNA of the tumor cell.
We have earlier reported the synthesis and radioiodination of the 9-
aminoacridine derivatives N–[o–(acridin-9-ylamino)-alkyl]-3-trimethylstan-
nyl-benzamides where the alkyl group is propyl and octyl; and 2–(acridin-9-
ylamino)-3-(4-hydroxy-phenyl)-propionic acid.12
This work describes the syntheses of a series of 9-aminoacridine derivatives
labeled with 125I, for potential use in targeted nuclide therapy. These
Copyright # 2005 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2005; 48: 855–871

SYNTHESIS OF 9-AMINOACRIDINE
857
compounds are carboxylic acids (2a, 2b, *2b and 2c), phenols (3a, 3b and *3b)
and amines (4a, 4b, *4b and 4c) which are depicted in Figure 1.
Result and discussion
Synthesis
Carboxylic acid derivatives of acridine. The synthesis of the acridine derivatives
2a–c is outlined in Scheme 1. Commercially available 3-(4-hydroxy-phenyl)
propionic acid was converted to its corresponding ethyl ester by acid catalyzed
esterification. The resulting ester was reduced using lithium aluminum hydride
providing a high yield of the phenoxypropanol 6a. Iodination of 6a was
carried out with molecular iodine and silversulfate at room temperature to
yield the iodo derivative 6b in good conversion. The phenoxy propanol 6a and
6b were reacted with N-(3-bromopropyl)phthalimide in the presence of K2CO3
to provide good-to-excellent yield of the protected amino compounds 7a and
7b, respectively. Excess of the N-(3-bromopropyl)phthalimide was required for
complete consumption of the starting phenoxypropanols 6a and 6b. Removal
of the phthalimide group was achieved by refluxing hydrazine monohydrate to
afford the amines 8a and 8b.
The 9-phenoxyacridine was prepared from 9(10 H)-acridone via chloroacri-
dine according to the method reported in the literature.13,14 The reaction of
amines 8a and 8b with 9-phenoxyacridine in molten phenol afforded the
acridines 9a and 9b, respectively, within 30 min. Compounds 9a and 9b were
subsequently oxidized to the corresponding carboxylic acids 2a and 2b, using
Jones reagent. The iodo derivative 2b, was converted to the corresponding
O
X
X
iv
i, ii
N
(CH2)3
O
(CH2)3OH
HO
(CH2)2CO2H
HO
(CH2)3OH
6a: X = H
7a: X = H
7b: X = I
O
5
iii
6b: X = I
v
X
X
viii
vii
vi
2c
ix
*2b
(CH2)3
O
(CH2)3OH
H2N (CH2)3
(CH2)3OH
2b
O
HN
N
2a
9a: X = H
9b: X = I
8a: X = H
8b: X = I
Scheme 1. (i) Ethanol, H2SO4, D; (ii) LiAlH4, THF, D; (iii) I2/Ag2SO4,
CH2Cl2, RT; (iv) K2CO3, N-(3-bromopropyl)phthalimide, acetone, D, (v)
N2H4.H2O, methanol, D; (vi) 9-phenoxyacridine, molten phenol, 808C; (vii)
CrO3, H2SO4, acetone, 0–108C; (viii) Sn2Me6, Pd(PPh3)4, DMF; (ix) Na125I,
chloramine-T (CAT)
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S. GHIRMAI ET AL.
I
i
HO
(CH2)2NH2
HO
(CH2)2NH2
10
11
iii
OPh
ii
3a
3b
*3b
iv
N
Scheme 2. (i) IPy2BF4, 10% TFA/CH2Cl2, RT; (ii) tyramine, phenol, 808C;
(iii) Na125I, CAT; (iv) iodotyramine 11, phenol, 808C
trimethylstannyl compound 2c using a palladium(0) catalyzed cross-coupling
reaction in good yield.
Phenolic derivatives of acridine. The synthesis of acridine derivatives 3a–b is
summarized in Scheme 2. Electrophilic monoiodination of commercially
available tyramine 10 was performed using bis(pyridine)-iodonium tetrafluor-
oborate15 in the presence of acid (10% TFA in CH2Cl2) giving a high yield of
the known16 ortho-iodo derivative 11. The compound 4-[2-(acridin-9-yl-
amino)-ethyl]-2-iodo-phenol (3b), was prepared from 9-phenoxyacridine and
iodotyramine 11 in molten phenol. The reaction resulted in total conversion
after stirring for 1 h at 808C. Compound 3a was synthesized from the reaction
of 9-phenoxyacridine with tyramine by means of a procedure similar to that
used to prepare 3b.
Amine derivatives of acridine. The synthesis of the acridine derivatives 4a–c is
depicted in Scheme 3. The tyramine derivatives 10 and 11 were protected with
a BOC protecting group using di-tert butyl dicarbonate in basic media to give
compound 12a and 12b, respectively, in quantitative yield. The compounds
12a and 12b were treated with K2CO3 and reacted with N-(3-bromopro-
pyl)phthalimide to give the di-protected amines 13a and 13b, respectively.
Selective deprotection17 of the phthalimide part was carried out using
hydrazine monohydrate to provide the BOC protected amines 14a and 14b
in good yields.
The amines 14a and 14b, were reacted with 9-phenoxyacridine to afford the
acridine derivatives 15a and 15b. The BOC protecting group was removed
using dry HCl in ethylacetate to give the hydrochloride of compounds 4a and
4b. The iodide of compound 4b was exchanged with trimethyltin using a
palladium(II) catalyzed reaction to give the stannylated compound 4c in good
yield. This compound was used as a precursor for radioiodination and
compound 4b was used as a reference for the radioiodinated analog *4b.
Compound 4a was prepared in order to see whether direct radioiodination of
the ring is possible. This, however, was unsuccessful.
Copyright # 2005 John Wiley & Sons, Ltd.
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SYNTHESIS OF 9-AMINOACRIDINE
859
X
X
i
(CH2)2NH2
HO
HO
(CH2)2NHBOC
10: X = H
11: X = I
12a: X = H
12b: X = I
ii
X
O
X
iii
H2N (CH2)3
O
(CH2)2NHBOC
N (CH2)3
O
(CH2)2NHBOC
O
13a: X = H
13b: X = I
14a: X = H
14b: X = I
iv
X
v
vi
vii
O
(CH2)2NHBOC
4b
4c
*4b
(CH2)3
HN
N
4a
15a: X = H
15b: X = I
Scheme 3. (i) (BOC)2O, 10% Et3N/MeOH, 548C, aq. HCl; (ii) N-(3-
bromopropyl)phthalimide, K2CO3, acetone, reflux; (iii) N2H4.H2O, MeOH,
reflux; (iv) 9-phenoxyacridine, phenol, 808C; (v) dry HCl in EtOAc, RT; (vi)
Sn2Me6, (PPh3)2PdCl2, 1,4-dioxane, 858C; (vii) chloramine-T, Na125
I
Table 1. Radioiodinated yield of acridine derivatives using CAT as oxidant, 5.0 ll
aqueous 125I-solution (3.7 GBq/ml) and 5 min reaction time
Entry Substrate (mg/ml) CAT (mg/ml) Radioiodinated acridine derivatives Yield (%)
1
2
3
4
2c (1)
3a (1)
4c (0.5)
4c (2)
1
8
1
8
*2b
*3b
*4b
*4b
70 ꢀ 0.5
68 ꢀ 0.5
92 ꢀ 0.3
96 ꢀ 0.4
Radiolabeling
Radioiodination of compounds 2c, 3a and 4c with 125I was performed using
chloramine-T (CAT) as an oxidant. The various parameters, such as amount
of substrate, amount of oxidant and reaction time were optimized for each
reaction. The 125I labeled compounds were obtained in good-to-excellent
labeling yields in 5 min reaction time according to the radio-TLC analysis. The
radiochemical yields of the three labeled compounds *2b, *3b and *4b are
summarized in Table 1.
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860
S. GHIRMAI ET AL.
Figure 2. (a) Typical TLC-result for compound *4b using the general labeling
procedure. Peak 1 corresponds to radiolabeled compound, *4b ðRf ¼0:1Þ and
peak 2 corresponds to 125I stabilized with carrier NaI ðRf ¼0:8Þ against
oxidation. (b) Typical radio-TLC diagram of a blank experiment. Peak 2
corresponds to 125I stabilized with carrier NaI ðRf ¼0:8Þ against oxidation
Figure 2(a) displays an illustrative radio-TLC diagram of [125I]-iodide of
compound 4c using 20 mg of substrate in 40 ml of 1% acetic acid in methanol
solution, 5 ml 125I-solution (3.7 GBq/ml), and 10 ml Chloramine-T (CAT)
solution (1 mg/ml in MeOH). The radio-TLC diagram shows a small peak of
125I stabilized with carrier NaI ðRf ¼ 0:8Þ and a major peak with Rf¼0:1. This
peak appeared only in reaction mixtures containing the substrate and was
found to have the same Rf as the non-radioactive reference compound, 4b; it
thus, most likely represents the iodinated compound, *4b.
Blank experiments were performed using exactly the same conditions except
that neat 1% acetic acid in methanol was used instead of the acridine
derivatives. In all blank experiments, where no substrate or oxidant is added,
only the peak with Rf ¼ 0:8 (peak 2) was observed (see Figure 2(b)). This peak
has the same retention factor as does NaI. The small peak at the start and at
the end of the radio-TLC in the blank experiment are usually observed. The
peak at the start is generally considered to be due to the presence of an
oxidized form of [125I]iodide.
Experimental
General
1
1H and 13C spectra were recorded in CDCl3 (7.26 ppm H, 77.0 ppm 13C),
1
1
CD3OD (3.35 ppm H, 49.0 ppm 13C) or DMSO (2.49 ppm H, 39.5 ppm 13C)
on a Varian Unity 400 spectrometer operating at 400 and 100.6 MHz,
respectively. For column chromatography Merck silica gel 60 (230–400 mesh)
was used. TLC was performed using Merck Silica 60 F254 gel. All solvents were
dried according to standard methods unless otherwise stated. LC/MS was
Copyright # 2005 John Wiley & Sons, Ltd.
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SYNTHESIS OF 9-AMINOACRIDINE
861
conducted using AQA mass spectrometer with an electrospray positive
ionization method in methanol solution. High resolution mass spectroscopy
(HRMS) was conducted in Organisch Chemisches Institut der Universitaet
Muenster, Germany. Melting points are uncorrected and were obtained using
SMP3 Bibby Sterilin melting point apparatus. The notations ‘benz’ and ‘acr’
are used for benzene and acridine rings, respectively.
Materials for radiolabeling
Iodine-125, 370 MBq/99 ml as diluted solution in sodium hydroxide, was
purchased from Amersham Biosciences, Amersham, UK. Methanol (HPLC
grade) was used as supplied. High-quality ELGA water (resistance higher than
18 MO/cm3) was used in preparing aqueous solutions. N-Chloro-p-toluene-
sulfonamide sodium salt (chloramine-T, CAT) and sodium metabisulfite,
Na2S2O5 were both obtained from Sigma. Sodium iodide, NaI, pro analysis
was used for preparation of solutions as delivered. The solutions of CAT
(1.8 mg/ml solution in MeOH), Na2S2O5 (2.16 mg/ml solution in H2O) and
NaI (10 mg/ml solution in H2O) were always prepared fresh, 5 min before each
experiment. The solutions of acridine derivatives were also prepared before
each experiment.
Analytical techniques for radiolabeling
Silica gel 60 F254 thin layer chromatography plates (E. Merck, Darmstadt,
Germany) were used for analysis. The reaction mixture (1–2 ml) was applied on
a TLC plate, using a mixture of 20 ml (methanol): 40 ml (acetic acid) as eluent
for compound *4b, and 100% MeOH for compound *3b, and 5:1,
methanol:dichloromethane for *2b. The Rf values for the non-radiolabeled
iodoacridine derivatives were used for comparison and were the same as those
of their radiolabeled analog. The position of standard chromatography spots
were determined visually either using UV light or the naked eyes. The
distribution of radioactivity along the TLC strips (100 ꢁ 50 mm, elution path
80 mm) was measured using a CycloneTM storage phosphor system (Packard
Instruments Company Inc., Downers Grove, US) and analyzed using the
OptiQuantTM image analysis software.
Synthesis
Preparation of 4-(3-hydroxy-propyl)-phenol18 (6a). 3-(4-Hydroxy-phenyl)-
propionic acid (20.0 g, 0.120 mol) was dissolved in 300 ml of absolute ethanol.
H2SO4 (4.5 ml) was added and the solution was refluxed for 1 h 30 min. The
reaction mixture was then cooled to room temperature. Water (30 ml) was
added, and the ethanol was evaporated and the residue was extracted with
dichloromethane. The combined extract was washed with brine, dried over
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S. GHIRMAI ET AL.
MgSO4, filtered, evaporated and dried under reduced pressure to yield the 3-
(4-hydroxy-phenyl)-propionic acid ethyl ester in 99%. This compound was
used in the next reaction with out further purification.
To a suspension of LiAlH4 (7.78 g, 0.205 mol) in dry THF (250 ml), a
solution of 3-(4-hydroxy-phenyl)-propionic acid ethyl ester (21.50 g, 0.111 mol)
in dry THF (150 ml) was added dropwise at room temperature. The mixture
was stirred at 558C for 12 h. The reaction was quenched by cautiously adding
ethyl acetate, then water. The mixture was then acidified with conc.
hydrochloric acid. The solvent was evaporated. The mixture was extracted
with ethyl acetate. The combined organic layer was washed with water,
saturated NaHCO3 and finally with brine. Ethyl acetate was evaporated to
give colorless oil which crystallized upon standing. The reaction afforded the
pure compound 6a (13.5 g, 80% yield) after column chromatography
purification (3:1, ether pentane).
1H NMR (CDCl3): d 7.1 (d, 2H, J ¼ 8:6 Hz, benz), 6.78 (d, 2H, J ¼ 8:6 Hz,
benz), 3.72 (t, 2H, J ¼ 6:8 Hz, –CH2OH), 2.68 (t, 2H, J ¼ 7:8 Hz, PhCH2–),
1.9 (m, 2H, CH2CH2CH22); 13C NMR (CDCl3): d 153.7, 133.8, 129.46, 115.2,
62.3, 34.3, 31.1.
4-ð3-Hydroxy-propyl)-2-iodo-phenol (6b). Ag2SO4 (2.50 g, 8.01 mmol) and I2
(2.03 g, 8.01 mmol) were dissolved in dichloromethane. 4-(3-hydroxy-propyl)-
phenol 6a (1.23 g, 8.01 mmol) was then added. The reaction mixture was
stirred at room temperature for 24 h. The yellow precipitate was filtered off.
The filtrate was washed with sodiumthiosulfate (Na2S2O3), water and then
brine. The organic layer was dried over Mg2SO4, filtered and evaporated. The
crude product was purified by column chromatography (3:1, ether:pentane,
Rf ¼ 0:34) to afford compound 6b (1.56 g, 70% yield) as a white solid.
1
m:p: ¼ 83:8285:88C. H NMR (CDCl3): d 7.50 (s, 1H, benz), 7.06 (dd, 1H,
J ¼ 8:3, 2.0 Hz, benz), 6.90 (d, 1H, J ¼ 8:3 Hz, benz), 3.66 (t, 2H, J ¼ 6:5 Hz,
–CH2–OH), 2.62 (t, 2H, J ¼ 7:5 Hz, benz–CH2–), 1.83 (m, 2H, J ¼ 6:5 Hz,
–CH2–); 13C NMR (CDCl3): d 153.0, 137.8, 136.0, 130.2, 114.9, 85.6, 62.0,
34.2, 30.6.
2-{3-[4-(3-Hydroxy-propyl)-phenoxy]-propyl}-isoindole-1,3-dione (7a). 4-(3-
Hydroxy-propyl)-phenol 6a (1.00 g, 6.58 mmol) was dissolved in acetone.
K2CO3 (0.91 g, 6.58 mmol) and N-(3-bromopropyl)phthalimide (3.50 g,
13.20 mmol) were added successively to the solution. The mixture was allowed
to reflux for one day. The reaction was cooled to room temperature and after
filtration the solvent was evaporated to give the crude product. Purification by
column chromatography (4:1, CH2Cl2:acetone, Rf ¼ 0:62) provided com-
pound 7a as a white solid, in quantitative yield.
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SYNTHESIS OF 9-AMINOACRIDINE
863
m:p: ¼ 100:52106:58. C1H NMR (CDCl3): d 7.84 (m, 2H, phthalimide),
7.71 (m, 2H, phthalimide), 7.06 (d, 2H, J ¼ 8:3 Hz, benz), 6.73 (d, 2H,
J ¼ 8:3 Hz, benz), 4.00 (t, 2H, J ¼ 6:5 Hz, benzO–CH2), 3.90 (t, 2H,
J ¼ 7:2 Hz, CH2–OH), 3.65 (t, 2H, J ¼ 6:5 Hz, CH2–N), 2.62 (t, 2H,
J ¼ 7:8 Hz, benz–CH2), 2.17 (qn, 2H, J ¼ 6:5 Hz, benzO–CH2–CH2–), 1.85
(m, 2H, benz–CH2–CH2); 13C NMR (CDCl3): d 168.4, 156.9, 139.1, 133.9,
132.1, 129.2, 123.2, 114.4, 65.7, 62.3, 35.5, 34.4, 31.1, 28.4.
2-{3-[4-(3-Hydroxy-propyl)-3-iodo-phenoxy]-propyl}-isoindole-1,3-dione (7b).
The compound 7b was obtained in 86% yield from iodo compound 6b and
two equivalent of N-(3-bromopropyl)phthalimide in a similar method as
described for 7a. HRMS (m/z): calculated for (C20H20INO4+H+), (C20H20I-
NO4+Na), 467.0594, 488.0335; found 467.0506, 488.0329, respectively.
1
m:p: ¼ 138:72139:08C. H NMR (CDCl3): d 7.85-7.83 (m, 2H, phthalimide),
7.72-7.70 (m, 2H, phthalimide), 7.58 (s, 1H, benz), 7.08 (d, 1H, J ¼ 8:3 Hz,
benz), 6.70 (d, 1H, J ¼ 8:3 Hz, benz), 4.05 (t, 2H, J ¼ 6:6 Hz, benzO–CH2–),
3.97 (t, 2H, J ¼ 6:9 Hz, –CH2–OH), 3.65 (t, 2H, J ¼ 6:6 Hz, –CH2–N–), 2.60
(t, 2H, J ¼ 7:7 Hz, benz–CH2–), 2.23 (qn, 2H, J ¼ 6:6 Hz, benzO–
CH22CH22), 1.84 (m, 2H, benz–CH22CH22); 13C NMR (CDCl3): d
168.0, 156.0, 139.2, 136.2, 133.9, 129.3, 123.3, 112.0, 86.5, 67.1, 62.0, 35.6,
34.2, 30.6, 28.6.
3-[4-ðAmino-propoxy)-phenyl]-propan-1-ol (8a). To a solution of 2-{3-[4-(3-
hydroxy-propyl)-phenoxy]-propyl}-isoindole-1,3-dione 7a (1.00 g, 2.95 mmol)
in methanol was added hydrazine monohydrate (0.15 g, 2.95 mmol). The
reaction mixture was allowed to reflux overnight. The solvent was evaporated
and the crude product was purified by flash chromatography (3:2:0.04,
CH2Cl2:MeOH:Et3N, Rf ¼ 0:31) to provide the amine 8a (0.28 g, 46% yield)
as a white solid.
1H NMR (CDCl3): d 7.09 (d, 2H, J ¼ 8:4 Hz, benz), 6.81 (d, 2H,
J ¼ 8:4 Hz, benz), 4.02 (t, 2H, J ¼ 6:8 Hz, benzO–CH2), 3.65 (t, 2H,
J ¼ 7:0 Hz, –CH2–OH), 2.90 (t, 2H, J ¼ 6:8 Hz, CH2–N), 2.64 (t, 2H,
J ¼ 7:6 Hz, benz–CH2–), 1.91 (qn, 2H, J ¼ 6:8 Hz, benzO–CH22CH22), 1.85
(m, 2H, benz–CH22CH2); 13C NMR (CDCl3): d 157.1, 133.9, 129.2, 114.3,
65.8, 62.1, 39.3, 34.4, 33.0, 31.1.
3-½4-ð3-Amino-propoxy)-2-iodo-phenyl]-propan-1-ol (8b). The compound 8b
was synthesized in 85% yield from 7b by a similar procedure to that used for
8a.
HRMS (m/z): calculated for (C12H18INO2+H+), (C12H18INO2+Na),
336.0461, 358.0280; found 336.0451, 358.0269, respectively. 1H NMR
(CDCl3): d 1.81-1.86 (m, 2H, benz–CH22CH22), 1.91-1.98 (m, 2H, benzO–
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864
S. GHIRMAI ET AL.
CH22CH22), 2.60 (t, 2H, J ¼ 7:6 Hz, benz–CH2–), 2.98 (t, 2H, J ¼ 6:8 Hz,
–CH2–N), 3.64 (t, 2H, J ¼ 7:0 Hz, CH2–OH), 4.07 (t, 2H, J ¼ 7:1 Hz, benzO–
CH2–), 6.72 (d, 1H, J ¼ 8:2 Hz, benz), 7.10 (d, 1H, J ¼ 8:2 Hz, benz), 7.60
( s, 1H, benz); 13C NMR (CDCl3): d 30.6, 32.6, 34.2, 39.4, 61.8, 67.4, 86.6,
111.9, 129.3, 136.2, 139.1, 155.7.
3-{4-[3-(Acridin-9-ylamino)-propoxy]-phenyl}-propan-1-ol (9a). 3-[4-(Amino-
propoxy)-phenyl]-propan-1-ol 8a (0.17 g, 0.83 mmol) in molten phenol was
added to a solution of 9-phenoxyacridine (0.23 g, 0.83 mmol) in molten phenol.
The mixture was stirred at ꢂ808C for 30 min. The mixture was then cooled to
room temperature and subjected to flash chromatography (4:1:0.03,
CH2Cl2:MeOH: Et3N, Rf ¼ 0:51) giving yellow powder of compound 9a
(0.22 g, 67% yield).
1H NMR (CDCl3): d 1.86 (m, 2H, benz–CH22CH22), 2.17 (qn, 2H,
J ¼ 5:4, 6.2Hz, benzO–CH22CH22), 2.65 (t, 2H, J ¼ 7:1 Hz, benz–CH2),
3.67 (t, 2H, J ¼ 6:2 Hz, CH2–N), 4.02 (t, 2H, J ¼ 6:2 Hz, CH2–OH), 4.13
(t, 2H, J ¼ 5:4 Hz, benzO–CH2), 6.82 (d, 2H, J ¼ 8:3 Hz, benz), 7.09 (d, 2H,
J ¼ 8:3 Hz, benz), 7.30 (t, 2H, J ¼ 8:6 Hz, acr), 7.63 (t, 2H, J ¼ 8:6 Hz, acr),
8.04 (d, 2H, J ¼ 8:6 Hz, acr), 8.11 (d, 2H, J ¼ 8:6 Hz, acr); 13C NMR
(CDCl3): d 30.52, 31.14, 34.43, 49.26, 61.64, 67.05, 114.23, 116.45, 122.77,
122.88, 128.96, 129.38, 129.83, 134.71, 149.08, 151.38, 156.43.
3-{4-[3-(Acridin-9-ylamino)-propoxy]-2-iodo-phenyl}-propan-1-ol (9b). This
compound was prepared in 59% yield from 8b using a method similar to
that described for 9a.
HRMS (m/z): calculated for (C25H25IN2O2+H+), 513.1039; found
1
513.1058. H NMR (CDCl3): d 1.85 (m, 2H, J ¼ 6:3 Hz, benz–CH2–CH2–),
2.27 (m, 2H, J ¼ 5:5 Hz, 6.3 Hz, benzO–CH22CH22), 2.62 (t, 2H,
J ¼ 7:1 Hz, benz–CH22), 3.67 (t, 2H, J ¼ 6:3 Hz, CH2–N), 4.12 (t, 2H,
J ¼ 6:3 Hz, CH2–OH), 4.17 (t, 2H, J ¼ 5:5 Hz, benzO–CH2–), 6.69 (d, 1H,
J ¼ 8:1 Hz, benz), 7.08 (m, 1H, J ¼ 8:1 Hz, benz), 7.35 (m, 2H, J ¼ 7:9 Hz,
acr), 7.62 (s, 1H, benz), 7.66 (m, 2H, J ¼ 8:4 Hz, acr), 8.06 (d, 2H, J ¼ 8:4 Hz,
acr), 8.18 (d, 2H, J ¼ 8:8 Hz, acr); 13C NMR (CDCl3): d 30.6, 30.8, 34.4, 48.7,
61.8, 67.8, 86.7, 112.5, 117.2, 123.1, 123.2, 129.4, 129.9, 136.9, 139.2, 151.4,
155.4.
3-{4-[3-(Acridin-9-ylamino)-propoxy]-phenyl}-propionic acid (2a). 3-{4-[3-
(Acridin-9-ylamino)-propoxy]-phenyl}-propan-1-ol, 9a (20 mg, 0.050 mmol)
was dissolved in acetone (2 ml) and cooled to 08C. CrO3 (20.7 mg, 0.21 mmol)
was dissolved in 3 M aqueous H2SO4 (0.5 ml) and added to the solution
dropwise over a period of 15 min. The mixture was stirred at 0–108C for 3 h.
The reaction was quenched with water (2 ml). Column chromatography (4:1,
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SYNTHESIS OF 9-AMINOACRIDINE
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MeOH:CH2Cl2, Rf¼0:41) afforded a yellow powder of compound 2a (19 mg,
90% yield).
1H NMR (CD3OD): d 2.41 (m, 2H, benzO–CH22CH22), 2.54 (t, 2H,
J ¼ 7:2 Hz, benz–CH2–), 2.79 (t, 2H, J ¼ 7:4 Hz, –CH2–CO2H), 4.11 (t, 2H,
J ¼ 5:4 Hz, –CH2–N), 4.37 (t, 2H, J ¼ 6:4 Hz, benzO–CH2–), 6.67 (d, 2H,
J ¼ 8:2 Hz, benz), 7.00 (d, 2H, J ¼ 8:2 Hz, benz), 7.51 (t, 2H, J ¼ 8:3 Hz, acr),
7.75 (d, 2H, J ¼ 8:3 Hz, acr), 7.91 (t, 2H, J ¼ 8:3 Hz, acr), 8.47 (d, 2H,
J ¼ 8:3 Hz, acr); 13C NMR (CD3OD): d 30.3, 31.0, 36.8, 52.0, 62.2, 66.6, 73.5,
115.3, 119.6, 124.9, 130.3, 134.4, 136.4, 158.3, 159.6, 175.0.
3-{4-[3-(Acridin-9-ylamino)-propoxy]-2-iodo-phenyl}-propionic acid (2b).
This compound was, a yellow powder, prepared in 92% from compound 9b
by using a similar procedure as was used for compound 2a.
m:p: ¼ 142:02144:08C. 1H NMR (CD3OD): d 2.43 (m, 2H, benzO–
CH22CH22), 2.50 (t, 2H, J ¼ 7:4 Hz, benz–CH2–), 2.71 (t, 2H, J ¼ 7:4 Hz,
–CH2–CO2H–), 4.12 (t, 2H, J ¼ 5:3 Hz, –CH2–N), 4.35 (t, 2H, J ¼ 6:5 Hz,
benzO–CH2–), 6.71 (d, 1H, J ¼ 8:0 Hz, benz), 7.01 (d, 1H, J ¼ 8:0 Hz, benz),
7.43–7.45 (m, 3H, acr and benz), 7.70 (d, 2H, J ¼ 8:2 Hz, acr), 7.82 (t, 2H,
J ¼ 8:2 Hz, acr), 8.42 (d, 2H, J ¼ 8:2 Hz, acr); 13C NMR (CD3OD): d 30.2,
30.4, 36.4, 52.1, 67.5, 86.9, 113.4, 119.6, 125.1, 130.5, 136.3, 136.6, 140.0,
156.8, 174.7.
3-{4-[3-(Acridin-9-ylamino)-propoxy]-3-trimethylstannyl-phenyl}-propionic acid
(2c). Compound 2a (57.0 mg, 0.12 mmol) was dissolved in dry DMF and
argon was bubbled through the solution for 15 min. Hexamethylditin (0.142 g,
0.48 mmol) and tetrakis triphenyl phosphine palladium(0) (27.7 mg,
0.024 mmol) were added successively. The reaction mixture was then stirred
at 908C for 3 h under an argon atmosphere. The black precipitate was filtered
off and the solvent was evaporated. The crude product was then subjected to
flash chromatography, 7:1 CH2Cl2:MeOH with a few drops of triethylamine as
a mobile phase. The reaction provided a yellow powder of compound 2c
(50 mg, 74% yield).
1H NMR (CDCl3): d 0.24 (s, tin satellites, 9H, Sn(CH3)3), 2.59-2.63 (m, 4 H,
benzO–CH2–CH2), 2.90 (t, 2H, J ¼ 7:4 Hz, –CH2–CO2–), 4.27-4.34 (m, 4 H, –
CH2N– and benzO–CH2–), 6.84 (d, 1H, J ¼ 8:3 Hz, benz), 7.06–7.12 (m, 3H,
benz and acr), 7.19 (s, 1H, benz), 7.40 (t, 2H, J ¼ 8:6 Hz, acr), 7.89 (d, 2H,
J ¼ 8:6 Hz, acr), 8.15 (d, 2H, J ¼ 8:6 Hz, acr); 13C NMR (CD3OD): d ꢃ8.87,
30.2, 30.4, 36.4, 52.1, 67.5, 86.9, 113.4, 119.6, 125.1, 130.5, 136.2, 136.6, 140.0,
156.8, 174.7.
4-(2-Amino-ethyl)-2-iodo-phenol (11)16. Tyramine (0.100 g, 0.73 mmol) was
dissolved in 10% triflouroacetic acid in dichloromethane. Solid IPy2BF4
(0.41 g, 1.09 mmol) was added and the reaction was stirred at room
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S. GHIRMAI ET AL.
temperature for 1 h. The solvent was evaporated under reduced pressure. The
residue was dissolved in methanol, sodium bicarbonate was added and the
mixture was stirred for 1 h. The salt was filtered off and the solvent was
evaporated. The crude product was then purified by column chromatography
(1:9, methanol:CH2Cl2) to afford compound 11 (0.183 g, 95% yield) as a white
solid.
1H NMR (CD3OD): d 7.61 (d, 1H, J ¼ 2:4 Hz, benz), 7.09 (dd, 1H, J ¼ 7:7,
2.4 Hz, benz), 6.80 (d, 1H, J ¼ 7:7 Hz, benz), 3.10 (t, 2H, J ¼ 7:4 Hz, NCH2–),
2.82 (t, 2H, J ¼ 7:4 Hz, –CH2–); 13C NMR (CD3OD): d 157.3, 140.4, 130.9,
130.6, 116.1, 85.0, 42.0, 33.1.
4-[2-(Acridin-9-ylamino)-ethyl]-phenol (3a). A mixture of 9-phenoxyacridine
(70.00 mg, 0.26 mmol) and tyramine (35.4 mg, 0.26 mmol) was dissolved in
molten phenol. The solution was stirred at ꢂ808C for 1 h. The mixture was
flashed on a silica gel with 100% ethylacetate in order to remove the phenol.
The compound was then recovered by eluting with 4:1, CH2Cl2:MeOH. The
reaction provided a yellow powder of compound 3a (78 mg, 95% yield).
HRMS (m/z): calculated for (C21H18N2O+H+), 315.1497; found 315.1465.
1H NMR (in CD3OD): d 8.40 (d, 2H, J ¼ 9:3 Hz, acr), 7.89 (t, 2H,
J ¼ 9:3 Hz, acr), 7.79 (d, 2H, J ¼ 9:3 Hz, acr), 7.50 (t, 2H, J ¼ 9:3 Hz, acr),
6.99 (d, 2H, J ¼ 8:1 Hz, benz), 6.58 (d, 2H, J ¼ 8:1 Hz, benz), 4.33 (t, 2H,
J ¼ 6:0 Hz, NCH2–), 3.10 (t, 2H, J ¼ 6:0 Hz, –CH2–); 13C NMR (CD3OD): d
159.5, 157.4, 142.1, 135.9, 130.9, 129.4, 126.3, 124.8, 120.5, 116.4, 114.3, 52.2,
36.1.
4-[2-(Acridin-9-ylamino)-ethyl]-2-iodo-phenol (3b). Synthesis was carried out
using iodotyramine in the procedure similar to that used for 3a to give 95%
yield of 3b. HRMS (m/z): calculated for (C21H17IN2O+H+), 441.0464; found
441.0519.
1H NMR (CD3OD): d 8.37 (d, 2H, J ¼ 7:9 Hz, acr), 7.90 (t, 2H, J ¼ 7:9 Hz,
acr), 7.76 (d, 2H, J ¼ 7:9 Hz, acr), 7.52 (t, 2H, J ¼ 7:9 Hz, acr), 7.32 (s, 1H,
benz), 6.84 (dd, 1H, J ¼ 7:8, 1.7 Hz, benz), 6.50 (d, 1H, J ¼ 7:8 Hz, benz), 4.38
(t, 2H, J ¼ 6:9 Hz, NCH2–), 3.03 (t, 2H, J ¼ 6:9 Hz, CH2–); 13C NMR
(CD3OD): d 160.5, 156.9, 140.8, 136.4, 131.4, 131.0, 124.9, 119.7, 115.7, 84.5,
52.0, 35.7.
[2-(4-Hydroxy-phenyl)-ethyl]-carbamic acid tert-butyl ester (12a). Tyramine
(0.10 g, 0.73 mmol) was added to a 10% solution of triethylamine in methanol
(20 ml). Di-tert butyl dicarbonate (0.39 g, 1.46 mmol) was then added while
stirring continuously. The reaction was stirred at 548C for 30 min. The
reaction mixture was cooled to room temperature and the solvent was
evaporated under reduced pressure. The residue was dissolved in ethylacetate.
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SYNTHESIS OF 9-AMINOACRIDINE
867
Ice-cold aqueous HCl (pHꢂ3, 3 ml) was added. The solution was stirred at
08C for 10 min, and extracted with ethylacetate (3 ꢁ 20 ml). The organic
extracts were combined and dried over Na2SO4, filtered and evaporated under
reduced pressure. The crude product was purified by column chromatography
(8:1, CH2Cl2:MeOH) to give the pure product 12a (0.17 g, 98% yield) as a
white solid.
1H NMR (CDCl3): d 6.97 (d, 2H, J ¼ 8:0 Hz, benz), 6.79 (d, 2H,
J ¼ 8:0 Hz, benz), 6.60 (bs, 1H, OH), 4.71 (bs, 1H, NH), 3.32 (m, 2H,
CH2N), 2.69 (t, 2H, J ¼ 7:0 Hz, benz–CH2), 1.46 (bs, 9H, (CH3)3); 13C NMR
(CDCl3): d 156.3 (C¼¼O), 154.9, 130.0, 129.7, 115.5, 79.6, 42.0, 35.1, 28.3.
[2-(4-Hydroxy-3-iodo-phenyl)-ethyl]-carbamic acid tert-butyl ester (12b). A
yield of 72% of this compound was obtained using the same procedure as was
used for compound 12a.
HRMS (m/z): calculated for (C13H18INO3+Na), 386.0229; found 386.0228.
1
m:p: ¼ 128:42128:98C. H NMR (CDCl3): d 7.48 (s, 1H, benz), 7.03 (d, 1H,
J ¼ 8:2 Hz, benz), 6.89 (d, 1H, J ¼ 8:2 Hz, benz), 6.03 (bs, 1H, OH), 4.59 (bs,
1H, NH), 3.30 (m, 2H, CH2–N), 2.68 (t, 2H, J ¼ 7:1 Hz, CH2); 13C NMR
(CDCl3): d 156.0, 153.8, 138.4, 132.8, 130.4, 115.0, 85.4, 79.5, 41.8, 34.8, 28.4.
(2-{4-[3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-propoxy]-phenyl}-ethyl)-carba-
mic acid tert-butyl ester (13a). A mixture of BOC protected tyramine 12a
(0.10 g, 0.42 mmol), N-(3-bromopropyl)phthalimide (1.35 g, 5.04 mmol) and
potassium carbonate (58.30 mg, 0.42 mmol) was dissolved in acetone. The
reaction mixture was refluxed overnight under an inert atmosphere. The
reaction was cooled to room temperature and the solvent was evaporated after
filtration. The crude product was subject to flash chromatography using 2:1
pentane:ether until all excess bromophthalimide was eluted. The pure
compound was then eluted from 100% ether. The reaction afforded (0.165 g,
93% yield) of compound 13a as a white solid.
1
m:p: ¼ 123:92125:08C. H NMR (CDCl3): d 7.85 (m, 2H, phthalimide),
7.72 (m, 2H, phthalimide), 7.05 (d, 2H, J ¼ 8:3 Hz, benz), 6.75 (d, 2H,
J ¼ 8:3 Hz, benz), 4.02 (t, 2H, J ¼ 6:0 Hz, CH2–O), 3.90 (t, 2H, J ¼ 6:0 Hz,
CH22phthalimide), 3.30 (q, 2H, J ¼ 7:0 Hz, CH2–NH), 2.70 (t, 2H,
J ¼ 7:0 Hz, CH2–benz), 2.18 (qn, 2H, J ¼ 6:0 Hz, CH2–CH22CH2), 1.40 (s,
9H, BOC); 13C NMR (CDCl3): d 168.3, 157.3, 155.8, 134.2, 132.1, 131.0,
129.9, 123.5, 114.9, 79.2, 65.9, 41.9, 35.8, 29.9, 28.7, 28.6.
(2-{4-[3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-propoxy]-3-iodo-phenyl}-ethyl)-
carbamic acid tert-butyl ester (13b). This compound was prepared in 86%
yield using a procedure similar to that described for 13a.
1H NMR (CDCl3): d 7.81 (dd, 2H, J ¼ 5:4, 3.1 Hz, phthalimide), 7.69 (dd,
2H, J ¼ 5:4, 3.1 Hz, phthalimide), 7.55 (s, 1H, benz), 7.07 (dd, 1H, J ¼ 8:5,
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S. GHIRMAI ET AL.
2.0 Hz, benz), 6.70 (d, 1H, J ¼ 8:5 Hz, benz), 4.58 (bs, 1H, NH), 4.04 (t, 2H,
J ¼ 5:9 Hz, CH2–O), 3.95 (t, 2H, J ¼ 7:0 Hz, CH22phthalimide), 3.29 (q, 2H,
J ¼ 7:0 Hz, CH2–NH), 2.67 (t, 2H, J ¼ 7:4 Hz, CH2–benz), 2.21 (m, 2H,
J ¼ 5:9 Hz, CH2–CH22CH2), 1.40 (s, 9H, BOC); 13C NMR (CDCl3): d 168.3,
155.9, 155.7, 139.5, 133.8, 133.3, 132.2, 129.6, 123.2, 112.0, 86.7, 67.0, 41.7,
35.5, 34.7, 28.5, 28.3.
f2-[4-(3-Amino-propoxy)-phenyl]-ethyl}-carbamic acid tert-butyl ester
(14a). To compound 13a (0.16 g, 0.38 mmol) dissolved in methanol (75 ml)
was added hydrazine monohydrate (0.37 ml, 7.6 mmol). The reaction mixture
was refluxed overnight. The reaction was cooled to room temperature and the
solvent was evaporated. The residue was dissolved in 8:1, CH2Cl2:MeOH. The
insoluble part was filtered off, and washed several times with the solvent. The
solvent was evaporated and the residue was subject to flash chromatograpy
with the solvent system 8:1, CH2Cl2: MeOH until all the phthalhydrazide was
eluted. The compound was then recovered by eluting with 4:1:0.01
CH2Cl2:MeOH:Et3N to give pure compound 14a (100 mg, 90% yield) as a
white solid.
m:p: ¼106:92108:08C. 1H NMR (CDCl3): d 7.10 (d, 2H, J ¼ 8:7 Hz, benz),
6.83 (d, 2H, J ¼ 8:7 Hz, benz), 4.50 (bs, 1H, NHCO), 4.03 (t, 2H, J ¼ 5:8 Hz,
CH2–O), 3.33 (m, 2H, CH2NCO), 2.91 (t, 2H, J ¼ 6:8 Hz, CH2NH2), 2.74 (t,
2H, J ¼ 6:9 Hz, benz–CH2), 1.92 (m, 2H, CH2–CH22CH2), 1.43 (bs, 9H,
(CH3)3); 13C NMR (CDCl3): d 157.6, 155.9, 131.0, 129.7, 114.6, 79.0, 65.9,
41.9, 39.3, 35.3, 33.0, 28.4.
f2-[4-(3-Amino-propoxy)-3-iodo-phenyl]-ethyl}-carbamic acid tert-butyl ester
(14b). Obtained in 87% yield from compound 13b using a procedure similar
to that used for compound 14a.
m:p: ¼ 153:12155:78C. 1H NMR (CDCl3): d 7.54 (s, 1H, benz), 7.08 (d, 1H,
J ¼ 9:1 Hz, benz), 6.73 (d, 1H, J ¼ 9:1 Hz, benz), 4.72 (bs, 1H, NHCO), 4.10
(t, 2H, J ¼ 5:8 Hz, CH2–O), 3.26 (m, 4 H, CH2NCO, CH2NH2), 2.65 (t, 2H,
J ¼ 6:8 Hz, benzCH2), 2.26 (m, 2H, CH2–CH22CH2), 1.39 (bs, 9H, (CH3)3);
13C NMR (in CDCl3), d (ppm): 168.3, 156.2, 156.1, 139.7, 133.7, 130.0, 129.9,
114.8, 112.3, 86.9, 67.4, 42.0, 38.9, 35.0, 31.3, 28.6.
(2-{4-[3-(Acridin-9-ylamino)-propoxy]-phenyl}-ethyl)-carbamic acid tert-bu-
tyl ester (15a). A mixture of amine 14a (50.00 mg, 0.17 mmol), 9-phenox-
yacridine (46.1 mg, 0.17 mmol) and phenol was stirred at 808C for 1 h. The
mixture was cooled to room temperature and then subject to column
chromatography. Phenol was first eluted with 100% ethylacetate and the
product was then recovered by eluting with 3:1:0.01, CH2Cl2: MeOH:Et3N.
The reaction provided a quantitative yield of compound 15a as a white solid.
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SYNTHESIS OF 9-AMINOACRIDINE
1
869
m:p: ¼ 112:02114:08C. H NMR (CDCl3): d 8.13 (d, 2H, J ¼ 8:6 Hz, acr),
7.99 (t, 2H, J ¼ 8:6 Hz, acr), 7.60 (t, 2H, J ¼ 7:8 Hz, acr), 7.30 (d, 2H,
J ¼ 7:8 Hz, acr), 7.10 (d, 2H, J ¼ 8:7 Hz, benz), 6.83 (d, 2H, J ¼ 8:7 Hz,
benz), 4.70 (bs, 1H, NHCO), 4.16 (t, 2H, J ¼ 5:6 Hz, acr–N–CH2–), 4.07
(t, 2H, J ¼ 6:5 Hz, CH2–O), 3.34 (m, 2H, CH2NCO), 2.73 (t, 2H, J ¼ 7:9 Hz,
benzCH2–), 2.23 (m, 2H, CH2–CH22CH2–), 1.44 (s, 9H, BOC); 13C NMR
(CDCl3): d 157.0, 155.9, 151.9, 131.7, 130.1, 129.8, 128.2, 123.1, 122.8, 116.2,
114.4, 79.0, 66.7, 48.8, 41.9, 35.3, 30.6, 28.4.
(2-{4-[3-(Acridin-9-ylamino)-propoxy]-3-iodo-phenyl}-ethyl)-carbamic acid
tert-butyl ester (15b). A 91% yield of this compound was obtained using a
procedure similar to that described for 15a.
HRMS (m/z): calculated for (C29H32IN3O3+H+), 598.1567; found
598.1571. m:p: ¼ 105:32106:88C. 1H NMR (CDCl3): d 8.18 (d, 2H,
J ¼ 8:3 Hz, acr), 7.91 (t, 2H, J ¼ 8:3 Hz, acr), 7.55 (s, 1H, benz), 7.52 (t,
2H, J ¼ 8:0 Hz, acr), 7.23 (d, 2H, J ¼ 7:0 Hz, acr), 7.02 (d, 1H, J ¼ 8:2 Hz,
benz), 6.63 (d, 1H, J ¼ 8:2 Hz, benz), 4.85 (bs, 1H, NHCO), 4.13 (m, 4 H, acr–
N–CH2, –CH2–O–), 3.3 (m, 2H, CH2NCO–), 2.66 (t, 2H, J ¼ 6:9 Hz,
benzCH2–), 2.23 (m, 2H, J ¼ 5:7 Hz, –CH2–CH22CH2–), 1.43 (s, 9H,
BOC); 13C NMR (CDCl3): d: 155.8, 152.9, 146.0, 140.2, 133.8, 131.7, 131.6,
130.1, 126.7, 124.6, 122.9, 122.1, 115.5, 113.0, 86.5, 67.2, 47.8, 42.0, 34.8, 30.4,
28.9.
Acridin-9-yl-{3-[4-(2-amino-ethyl)-phenoxy]-propyl}-amine (4a). To a solu-
tion of compound 15a (0.14 g, 0.29 mmol) in methanol, 5 ml of 12.5 M dry HCl
in ethylacetate was added. The resulting solution was stirred for 18 h. The
completion of the reaction was confirmed by TLC (CH2Cl2:MeOH:HCOOH,
9:1:0.01). The reaction resulted in quantitative yield of 4a as a yellow powder.
HRMS (m/z): calculated for (C24H25N3O+H+), 372.2076; found 372.2079.
1H NMR (CD3OD): d 8.54 (d, 2H, J ¼ 8:3 Hz, acr), 7.9 (t, 2H, J ¼ 8:3 Hz,
acr), 7.83 (d, 2H, J ¼ 8:3 Hz, acr), 7.55 (t, 2H, J ¼ 8:3 Hz, acr), 7.10 (d, 2H,
J ¼ 8:0 Hz, benz), 6.74 (d, 2H, J ¼ 8:0 Hz, benz), 4.40 (t, 2H, J ¼ 5:9 Hz,
acrN–CH2–), 4.15 (t, 2H, J ¼ 4:8 Hz, benzO–CH2–), 3.09 (t, 2H, J ¼ 7:7 Hz,
–CH22NH3), 2.87 (t, 2H, J ¼ 7:7 Hz, benz–CH2–), 2.45 (m, 2H, –CH2–
CH22CH2–); 13C NMR (CDCl3): d 159.7, 152.0, 140.6, 136.4, 130.8, 130.2,
125.0, 119.6, 115.8, 113.0, 66.7, 47.9, 42.1, 33.6, 30.3.
Acridin-9-yl-{3-[4-(2-amino-ethyl)-2-iodo-phenoxy]-propyl}-amine (4b). Com-
pound 4b was prepared using the same method as for the amine 4a.
HRMS (m/z): calculated for (C24H24IN3O+H+), 498.1042; found
498.1089. m:p: ¼ 257:02259:08C. 1H NMR (CD3OD): d 8.57 (d, 2H,
J ¼ 8:5 Hz, acr), 7.96 (t, 2H, J ¼ 8:5 Hz, acr), 7.81 (d, 2H, J ¼ 8:5 Hz, acr),
7.63 (d, 1H, J ¼ 2:3 Hz, benz), 7.57 (t, 2H, J ¼ 8:5 Hz, acr), 7.19 (dd, 1H,
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J ¼ 8:7, 2.3 Hz, benz), 6.88 (d, 1H, J ¼ 8:7 Hz, benz), 4.50 (t, 2H, J ¼ 7:1 Hz,
acrN–CH2–), 4.23 (t, 2H, J ¼ 5:9 Hz, benzO–CH2–), 3.1 (t, 2H, J ¼ 7:5 Hz,
–CH22NH3), 2.85 (t, 2H, J ¼ 8:2 Hz, benz–CH2–), 2.51 (m, 2H, –CH2–
CH22CH2–); 13C NMR (CDCl3): d 158, 152.0, 140.6, 136.4, 132.6, 131.2,
125.1, 119.7, 115.0, 113.8, 87.3, 67.7, 48.2, 41.9, 33.1, 30.2.
Acridin-9-yl-{3-[4-(2-amino-ethyl)-2trimethylstannyl-phenoxy]-propyl}-amine
(4c). The hydrogen chloride salt of compound 4b was stirred with aqueous
K2CO3 and extracted with CH2Cl2 to give the free amine. The organic phase
was dried over magnesium sulfate. The solvent was evaporated and this free
amine (20.0 mg, 0.04 mmol) was dissolved in dry 1,4-dioxane. The solution was
bubbled with argon for 10 min in order to remove oxygen and carbon dioxide.
Hexamethyldistannane (53.0 mg, 0.16 mmol) was added to the mixture and
argon was bubbled through the reaction mixture for 4 min. Finally, bis-
(triphenylphosphine)-palladium(II)-dichloride (9.20 mg, 0.01 mmol) was
added and the reaction mixture was stirred at 858C for 90 min. The reaction
mixture was cooled to room temperature and the catalyst was filtered off
through celite. After evaporation to dryness the crude mixture was applied to a
flash chromatography column and eluted with mobile phase CH2Cl2:MeOH,
6:1 to give compound 4c (18.2 mg, 85% yield) as a yellow powder.
1H NMR (CDCl3): d 8.10 (m, 4 H, acr), 7.66 (t, 2H, J ¼ 7:6 Hz, acr), 7.32
(m, 3H, acr+benz), 7.16 (d, 1H, J ¼ 8:6 Hz, benz), 6.76 (d, 1H, J ¼ 8:6 Hz,
benz), 4.12 (t, 2H, J ¼ 7:1 Hz, acrNCH2–), 4.03 (t, 2H, J ¼ 5:9 Hz, –CH2O–),
2.93 (m, 2H, –CH22NH3), 2.70 (t, 2H, J ¼ 8:2 Hz, benzCH2–), 2.25(m, 2H,
–CH2–CH22CH2–), 0.23 (s + tin satellites, 9H, JHSn ¼ 28 Hz, Sn(CH3)3); 13
C
NMR (CDCl3): d 177.1, 168.0, 158, 152.0, 140.8, 136.4, 132.4, 130.0, 129.9,
124.8, 122.4, 121.0, 120.6, 114.9, 113.8, 84.3, 68.2, 48.2, 41.9, 33.1, 30.2, ꢃ8.9.
General 125I-labeling procedure
The following stock solutions were prepared: Acridine derivatives (2 mg/ml) in
methanol. N-chloro-p-toluenesulfonamide sodium salt (8 mg/ml) was dissolved
in methanol prior to use.
In a typical labeling experiment 3.7 GBq/ml of [125I]iodide was used. To
40 ml of 1% acetic acid methanol solution of acridine derivative, 5.0 ml aqueous
125I-solution was added, followed by 10 ml CAT solution. The reaction mixture
was vortexed for 5 min, quenched by the addition of 10 ml sodium metabisulfite
solution, and 20 ml of NaI solution was added as carrier. Exact concentrations
of solutions are given in Table 1. After mixing the reaction mixture, samples
for radio-TLC analysis (1–2 ml) were collected. Blank experiments were run
using exactly the same conditions, but neat 1% acetic acid methanol solution
was used instead of the stock solution of acridine derivatives. All blank
experiments were tested in both TLC systems.
Copyright # 2005 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2005; 48: 855–871

SYNTHESIS OF 9-AMINOACRIDINE
871
Acknowledgements
This work was financially supported by the Swedish Cancer Foundation and
by INTAS (Grant No. 99-00806).
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J Label Compd Radiopharm 2005; 48: 855–871