Synthesis and Investigation of Tetrahydro-β-carboline Derivatives as Inhibitors of the Breast Cancer Resistance Protein (ABCG2)

Article abstract of DOI:10.1021/acs.jmedchem.6b00035

The breast cancer resistance protein (ABCG2) transports chemotherapeutic drugs out of cells, which makes it a major player in mediating multidrug resistance (MDR) of cancer cells. To overcome this mechanism, inhibitors of ABCG2 can be used. Only a few potent and selective ABCG2 inhibitors have been discovered, i.e., fumitremorgin C (FTC), Ko143, and the alkaloid harmine, which contain a tetrahydro-β-carboline or β-carboline backbone, respectively. However, toxicity and or instability prevent their use in vivo. Therefore, there is a need for further potent inhibitors. We synthesized and pharmacologically investigated 37 tetrahydro-β-carboline derivatives. The inhibitory activity of two compounds (51, 52) is comparable to that of Ko143, and they are selective for ABCG2 over ABCB1. Furthermore, they are able to reverse the ABCG2-mediated resistance toward SN-38 and inhibit the ATPase activity. The cytotoxicity data show that their inhibitory effect is substantially higher than their toxicity.

Full text of DOI:10.1021/acs.jmedchem.6b00035

Subscriber access provided by UNIV OF NEBRASKA - LINCOLN
Article
Synthesis and investigation of tetrahydro-#-carboline derivatives
as inhibitors of the Breast Cancer Resistance Protein (ABCG2)
Anna Spindler, Katja Stefan, and Michael Wiese
J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.6b00035 • Publication Date (Web): 09 Jun 2016
Downloaded from http://pubs.acs.org on June 10, 2016
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of Medicinal Chemistry is published by the American Chemical Society. 1155
Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
Synthesis and investigation of tetrahydroꢀβꢀcarboline derivatives as
inhibitors of the Breast Cancer Resistance Protein (ABCG2)
*
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Anna Spindler, Katja Stefan, Michael Wiese
Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
Abstract
The breast cancer resistance protein (ABCG2) transports chemotherapeutic drugs out of cells
which makes it a major player in mediating multidrug resistance (MDR) of cancer cells. To
overcome this mechanism, inhibitors of ABCG2 can be used. Only a few potent and selective
ABCG2 inhibitors have been discovered i.e. fumitremorgin C (FTC), Ko143, and the alkaloid
harmine, which contain a tetrahydroꢀβꢀcarboline or βꢀcarboline backbone, respectively.
However, toxicity and or instability prevent their use in vivo. Therefore there is a need for
further potent inhibitors. We synthesized and pharmacologically investigated 37 tetrahydroꢀβꢀ
carboline derivatives. The inhibitory activity of two compounds (51, 52) is comparable to
Ko143, and they are selective for ABCG2 over ABCB1. Furthermore they are able to reverse
the ABCG2ꢀmediated resistance toward SNꢀ38 and inhibit the ATPase activity. The
cytotoxicity data show that their inhibitory effect is substantially higher than their toxicity.
1
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 2 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Introduction
The ATP binding cassette (ABC) transporters represent a superfamily of membraneꢀtransport
proteins and are found ubiquitously in all organisms (eukaryotes and prokaryotes). While in
prokaryotes importers and exporters are present, in eukaryotes only exporters are found.
Using the energy obtained from the hydrolysis of ATP the exporters actively transport their
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
,2
substrates out of cells. There are 48 known human ABC transporters which are divided into
seven subfamilies ABCA – ABCG based on phylogenetic similarity. The typical structure of
an ABC transporter consists of two transmembrane domains (TMD) which are composed of
six αꢀhelices and two nucleotide binding domains (NBD), respectively. Some ABC
transporters are not specific but recognise a vast variety of structurally unrelated substrates,
and have a protective function in tissue homeostasis because they can transport amongst other
3,4,5
things toxins and xenobiotics out of the cell.
On the other hand, they have found to be
frequently expressed in tumor tissue and can thus, increase the transport of chemotherapeutics
out of the tumor cells. An overexpression of these transporters in tumors can cause MDR
5
,6,7
which can lead to the failure of cancer therapy.
The breast cancer resistant protein, now
7
termed ABCG2 according to the gene nomenclature was first described in 1998. It consists of
655 amino acids and has a molecular weight of 72 kDa. It contains one TMD and one NBD
only and thus represents a halfꢀtransporter, which forms the functional transporter most
8
probably by tetramerization.
Compared to ABCB1 the number of known ABCG2 inhibitors is much less. The neurotoxic
9
fungal toxin FTC is a potent and specific inhibitor of ABCG2. Ko143 is a nontoxic analogue
1
0
of FTC and the most potent inhibitor of ABCG2. For a long time Ko143 was claimed to be a
specific inhibitor for ABCG2, however, it was recently reported to inhibit also ABCB1 and
1
1
ABCC1 at low micromolar concentrations. Tetracyclic desmethoxy FTCꢀ and Koꢀ
derivatives with different substitution patterns (aliphatic, cyclic/aromatic) have been
2
ACS Paragon Plus Environment

Page 3 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
2,13
investigated for their inhibitory activity toward ABCG2.
substitution as present in Ko143 gave the best results.
In this case the isobutyl
14
The alkaloid harmine was also reported to be an ABCG2 inhibitor. All three compounds,
Ko143, FTC and harmine contain the same substructure, the tetrahydroꢀβꢀcarboline or βꢀ
carboline moiety, see Figure 1.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
On this basis, it was interesting to synthesize new derivatives with a tricyclic common
scaffold and different substituents and to investigate them for their inhibitory properties
toward ABCG2 in comparison to known inhibitors. Furthermore we examined the selectivity
of the compounds toward ABCG2. For selected derivatives also cell toxicity, their ability to
reverse MDR and their influence on the ATPase activity were determined.
Results and Discussion
Chemistry The investigated tetrahydroꢀβꢀcarbolines with different modifications at position
1, 2 and 6 were synthesized by the procedure depicted in Scheme 1. In general, the
compounds were synthesized by a PictetꢀSpengler reaction using tryptamine or 5ꢀ
methoxytrypamine, an appropriate aldehyde in presence of trifluoroacetic acid (TFA) in
dichloromethane (DCM) to form the 1ꢀsubstitutedꢀtetrahydroꢀβꢀcarboline (1ꢀ19) or the 1,6ꢀ
1
5
disubtitutedꢀtetrahydroꢀβꢀcarboline (20, Scheme 1) The intermediates were further reacted
with benzoylchloride or differently substituted benzoylchlorides in tetrahydrofuran (THF)
with triethylamine (TEA) to obtain the N2ꢀacylꢀ1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines (21ꢀ52)
and the N2ꢀacylꢀ1,6ꢀsubstitutedꢀtetrahydroꢀβꢀcarboline (53, Scheme 1). Two intermediates (2,
1
9) were reacted with benzyl bromide in dimethylformamide (DMF) and TEA to obtain the
1
6,17
N2ꢀarylꢀ1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines (56, 57).
The target compounds (1ꢀ(3,4ꢀdichlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀ
yl)(3ꢀmethoxyphenyl)methanone (52) and phenyl(1ꢀphenylꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀ
3
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 4 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
b]indolꢀ2(9H)ꢀyl)methanone (22) were further reacted with iodoethane in presence of sodium
hydride in DMF to form the N2ꢀacylꢀN9ꢀethylꢀ1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines (54,
18
55).
1
13
All test compounds were characterized by H NMR and C NMR and their purity was
confirmed by elemental analysis. All synthesized compounds contain a chiral centre at C1.
For biological investigation, the racemic mixtures were used.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Investigation of the ABCG2ꢀinhibitory activity in Hoechst 33342 and pheophorbide A
assays. All synthesized compounds were tested for their inhibitory potency using the Hoechst
33342 accumulation assay with Madin Darby Canine Kidney II (MDCK II) cells
overexpressing ABCG2.
Because of the high autofluorescence of harmine in the Hoechst 33342 assay it was
investigated with the pheophorbide A assay. Selected compounds were additionally tested in
the pheophorbide A assay to demonstrate that the results of both assays are comparable. The
comparison of the pIC50 values obtained in both assays shows a very high correlation of the
2
results with a squared correlation coefficient (r ) of 0.95 (Figure 2). This indicates that the
inhibitory effect is not specific for the substrate. The determined resulting IC50 values are
listed in Table 1. The 1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines derivatives (2, 3) which are
obtained by the PictetꢀSpengler reaction had no inhibitory effect on ABCG2, neither in the
Hoechst 33342 assay nor in the pheophorbide A assay. This result is in agreement with a
12
previous study, where a number of tricyclic FTC analogs were found to be all inactive.
However among tetracyclic derivatives potent inhibitors were found. Two N2ꢀacylꢀ1ꢀ
3
substititutedꢀtetrahydroꢀβꢀcarboline derivatives with a phenyl ring at R and an isobutyl (21:
1
IC50 = 2.33 µM) or phenyl (22: IC50 = 2.78 µM) substituent at R showed moderate and
comparable inhibitory activities. As variations on an aromatic ring system could be readily
introduced, we continued with substituted phenyl derivatives. Various compounds with
4
ACS Paragon Plus Environment

Page 5 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
variably substituted phenyl rings at R were prepared. The selection of the substituents was
based on availability and variations in physicochemical properties like sigmaꢀHammett and
lipophilicity. Figure 3 shows the selected substituents in a sigmaꢀpi scatter diagram. Linear
regression yields a highly significant correlation with both variables (eq. 1).
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
pIC50 = 0.458(±0.041) π + 0.425(±0.092) σ + 5.639(±0.027)
(1)
2
2
n = 13
All meta and/or paraꢀsubstituted derivatives were included in the correlation (e.g. compounds
2ꢀ27, 29, 32, 33, 35, 37ꢀ39). Orthoꢀsubstituted derivatives had to be omitted due to lack of
R = 0.954
R
= 0.945
s = 0.083
F = 104.5
adj
2
sigma values. In case of disubstituted compounds, the sigma values were either used as sum
of both positions or separately in the regression. If the sigmaꢀHammett values for the meta
and para position are considered separately, the correlation is not improved and the same
squared correlation coefficient is obtained.
According to the equation lipophilicity has a positive effect on inhibitory potency. This
relationship has been reported several times for homologous series of ABCB1 inhibitors. And
has been explained by the assumption that binding to the protein takes place from within the
membrane. Thus higher lipophilicity leads to higher membrane partitioning and to higher
local concentration. Electron withdrawing substituents favour the inhibition according to eq.
1. It can be speculated that their presence at the phenyl ring would favour πꢀπ interactions
with electron rich aromatic systems of aromatic amino acids of the protein.
Two compounds deviate from the relationship, namely the 3ꢀnitroꢀ and 4ꢀ
(trifluoromethyl)phenyl substituted derivatives (28, 30) that should be highly active. We
wanted to investigate whether these compounds are true outliers or probable solubility
problems could explain their deviation. To do this, we measured their solubility over the time
of the assay. For both compounds solutions of 10 µM, the highest concentration used, were
prepared and the absorption was followed over time. It was found that they steadily
precipitated and after 2 h the absorbance had decreased to 20 percent of its initial value,
5
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 6 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
meaning that at least 80 percent of the compound had been precipitated during the assay time.
Thus the apparent inactivity could be due to fast precipitation, decreasing their concentration
in the assay. Several other derivatives showed no or very low activity in the Hoechst 33342
assay. To exclude that their apparent low potency was due to low solubility, we determined
the absorption versus time profiles for them and for selected active compounds as controls
(nos. 22, 29, 34, 36, 48, 51, 54ꢀ57). Only for (1ꢀ(2ꢀbromophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀ
b]indolꢀ2(9H)ꢀyl)(phenyl)methanone (34) and 1ꢀ(2ꢀchlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀ
b]indolꢀ2(9H)ꢀyl)(phenyl)methanone (36) a strong precipitation with absorbance values down
to 40 percent of the initial absorbance was found, while the other investigated compounds
remained almost quantitatively in solution, disproving the assumption of low potency due to
low solubility. It should be noted that in no case a visible clouding was observed and the
solutions appeared clear.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
With regard to the structureꢀactivity relationship (SAR) of the effects of the various
substituents for a chloro and bromo substituent the position dependence of the substituent
influence on activity can be estimated: 3ꢀchloroꢀ, 4ꢀchloroꢀ and 4ꢀbromophenyl substitution
increases the inhibitory activity to a subꢀmicromolar range (37:0.869 µM; 38:0.741 µM;
35:0.687 µM), while the 2ꢀchloroꢀ (36) and 2ꢀbromophenyl (34) analogous have very low
potency, also when taking into account their solubility problem. The same impact can be
observed for the smaller fluorine substitution in ortho (31) or para (32) position to a lesser
extent. A highly potent compound with an IC50 of 0.328 was obtained by a 3,4ꢀdichlorophenyl
1
substitution at R (39). A substitution with 3,4ꢀdifluorophenyl (33) shows also a slightly
increasing effect on the inhibitory activity in comparison to the 4ꢀfluorophenyl (32). The
3
variation at R leads to different results. The substitution of the phenyl ring with a methoxy
group in position 4 has no or just a slight increasing effect on the inhibitory activity. An
exception to this is compound 48, which get just because of the 4ꢀmethoxyphenyl substitution
3
at R an inhibitory activity with an IC of 1.23 µM (in comparison to 30 = no inhibitory
5
0
6
ACS Paragon Plus Environment

Page 7 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
effect up to 10 µM). This effect may be due to the increased solubility of 48 in comparison to
1
3
0, as described above. For all compounds with the 3,4ꢀdifluorophenyl at R no distinct
3
effects of different substituents on R can be found (compare 33:1.10 µM; 40:1.26 µM;
44:1.10 µM; 49:0.805 µM). For other compounds, especially for the highly potent compounds
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
3
with 3,4ꢀdichlorophenyl at R the substitution pattern at R has a higher influence on the
inhibitory activity. In this case a 4ꢀchlorophenyl (42: 1.03 µM), 1ꢀnaphtyl (45: 1.32 µM) and
3
3
,4ꢀdimethoxyphenyl (43: 0.698 µM) at R decrease, while a 4ꢀmethoxyꢀ (51: 0.233 µM) or
3
ꢀmethoxyphenyl (52: 0.238 µM) increase the inhibitory activity in comparison to a
2
unsubstituted phenyl ring (39: 0.328 µM). The additional methoxy group (R ) in position 6
(53, IC50: 0.382 µM) has no enhancing effect on the inhibitory activity. The substitution at N2
with a benzyl (56, 57) instead of a benzoyl group has a strongly decreasing effect for the
inhibitory efficacy toward ABCG2. The same effect is observed for the compounds with an
additional alkyl substitution at N9 (54, 55).
Based on this results it can be assumed, that a chlorine or bromine substitution in meta or
1
para position at the phenyl ring in R gave highly potent compounds with a inhibitory activity
in subꢀmicromolar range. By substitution with a 3,4ꢀdichlorophenyl ring this effect could be
increased. Other substituents have just minor (except difluorophenyl) or strong decreasing
impacts on the inhibitory activity toward ABCG2 dependent on their lipophilic and electronic
3
properties. The variation at R influences the inhibitory activity toward ABCG2, but this
1
effect is depending on the substitution pattern in R . The hydrogen bond donorꢀacceptor
system of the hydrogen at N9 and the acyl group at N2 seems to be necessary for the
inhibitory activity. In general, all active compounds show a better inhibitory activity than the
alkaloid harmine (IC50: 5.08 µM). The inhibitory activity of compound 51 (IC50: 0.233 µM)
and 52 (IC50: 0.238 µM) is comparable to Ko143 (IC50: 0.225 µM).
7
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 8 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Investigation of the inhibitory activity on ABCB1 with the calceinꢀacetoxymethyl ester
(calcein AM) assay. All compounds were screened for ABCB1 inhibition to investigate their
selectivity toward ABCG2, see Figure 4. For this determination the calcein AM assay was
used with the A2780 adr cell line. The concentration of the test compounds and the reference
compound cyclosporine A (CsA) amounted to 10 µM. The most potent compounds on
ABCG2 (39, 51, 52, 53) are selective toward ABCG2 over ABCB1, because they show just a
slight effect on ABCB1 of less than 25% at 10 µM (Figure 4). All compounds with a response
of more than 25% were further investigated to determine their IC50 values, see Table 2. The
paraꢀacetamido substituted compound 29 shows similar inhibitory effects toward ABCB1
(7.40 µM) and ABCG2 (7.82 µM). All other compounds have a higher inhibitory activity
against ABCG2 than ABCB1. The potent compounds (with the exception of 49) with an IC50
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
<
1 µM on ABCG2 show only minor effects with IC 10 >.µM on ABCB1.
50
Investigation of cell toxicity and the ability to reverse MDR with the 3ꢀ(4,5ꢀ
dimethylthiazolꢀ2ꢀyl)ꢀ2,5ꢀdiphenyltetrazolium bromide (MTT) Assay
The MTT assay was used to determine the intrinsic cytotoxicity of the most active and
selective compounds 35, 38, 39, 51, 52 and 53 in comparison to the unsubstituted analog 22
and the known inhibitors harmine and Ko143. The MDCK II BCRP and wild type cells were
incubated for 72 h with different concentrations of the compounds up to 100 µM. Compounds
39, 51, 52 and 53 show a similar toxic effect on the viability of the cells (Table 3). But, the
effect on the cell viability is up to 20 fold weaker than their inhibitory efficacy against
ABCG2. Compound 22 shows a lower toxicity and is comparable to Ko143. Compound 35
and 38 possess the lowest toxicity of the tested compounds and their inhibitory efficacy is 20ꢀ
30 fold higher than their toxic effect. All tested compounds show similar toxicities to the
MDCK II BCRP and MDCK wildꢀtype cells, which suggests that they are no substrates of
8
ACS Paragon Plus Environment

Page 9 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
ABCG2. The alkaloid harmine exhibits the highest toxicity and its toxic effect on cell
viability is about 2 times stronger than the inhibitory potency.
Furthermore, the ability to reverse the multidrug resistance in ABCG2 overexpressing cells
was investigated with selected compounds and compared to the known inhibitor Ko143. The
cytotoxic agent SNꢀ38 is the active metabolite of irinotecan and a substrate of ABCG2.
Therefore, the cytotoxicity effect of SNꢀ38 in MDCK II BCRP cells was measured in absence
and presence of different concentrations of selected compounds. All tested compounds and
Ko143 are able to reverse the transport of SNꢀ38 out of the cells in a concentration dependent
manner (Table 4). The shift in the dose–response curves of SNꢀ38 in MDCK II BCRP cells in
presence of an ABCG2 inhibitor in different concentrations are shown in Figure 5. The most
potent compounds 39, 51, 52 and 53 show a 10fold weaker ability (1 µM vs. 0.1 µM) to
reverse MDR in comparison to Ko143, despite similar IC ꢀvalues. This effect is more
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
5
0
pronounced for compounds (22, 35, 38 and harmine) with higher IC50ꢀvalues in ABCG2
inhibition assays. This consistent difference between IC50ꢀvalues and MDR reversal for
Ko143 and our compounds points to the possibility of substrate specific interactions.
ATPase assay. The results of the investigation of selected compounds in relation to their
properties toward vanadate sensitive ATPase activity are shown in Figure 6.
For comparison, quercetin a known activator and Ko143 a known inhibitor of the ATPase
activity were included. Compounds 22, 35, 38, 39, 51, 52 and 53 inhibit the ATPase activity
at a concentration of 1 µM, to the level of inhibition by 1 µM of Ko143 (Figure 6). Contrary,
the alkaloid harmine shows no inhibitory effect on the ATPase activity. Furthermore, we
determined doseꢀresponse curves of the inhibitory effect on basal and quercetin stimulated
ATPase activity (Table 5). Figure 7 shows example curves for compound 53 and Ko143. The
most active compounds (39, 51, 52, and 53) possess IC50ꢀvalues one magnitude larger than
Ko143. Interestingly, there is a good linear relationship between pIC ꢀvalues in the Hoechst
50
9
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 10 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
2
2
33342 and ATPase assays for all derivatives, except Ko143 (R =0.85 (basal), R =0.89 (for
quercetin stimulated activity). This points to the involvement of ATPase activity inhibition.in
the mode of action of the compounds. Stimulation with quercetin shifts all IC50ꢀvalues to
higher values, by an approximately constant factor of nine, indicating a competitive
interaction with ATPase stimulation by quercetin.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Conclusion
In this study we show, that tricyclic tetrahydroꢀβꢀcarbolines are good inhibitors of ABCG2.
1
We have found that the substitution pattern at R and the acyl substitution at N2 are essential
for the selectivity and inhibitory activity toward ABCG2. The most potent analogs 51 and 52
are selective for ABCG2 and their inhibitory properties are similar to those of Ko143 and
much better than those of harmine. An advantage to Ko143 is that just a twoꢀstep synthesis is
required to obtain quickly and cost effectively a wide range of good inhibitors. The
cytotoxicity data of test compounds shows that the cell viability decrease after 72 h but the
inhibitory potency is still up to 20ꢀ30 fold higher. We showed that the compounds are able to
reverse the ABCG2ꢀmediated SNꢀ38 resistance, but this effect is less pronounced than for
Ko143. Furthermore, the compounds inhibit the basal ATPase activity in isolated ABCG2
containing recombinant baculovirusꢀinfected Spodoptera frugiperda ovarian cells (Sf9)
membranes. For the quercetin stimulated ATPase activity a competitive interaction is
observed. The alkaloid harmine did not prove to be a potent inhibitor of ABCG2 and shows a
high cytotoxicity.
Experimental section
Chemistry.
10
ACS Paragon Plus Environment

Page 11 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
All chemicals were purchased from Sigma Aldrich, Alfa Aeser, Acros and Merck. The
reactions were monitored by thin layer chromatography (TLC) with silica gel plates (Silica
1
Gel 60 F254, Merck). The structure and the purity of all compounds were confirmed by H and
1
3
C NMR and elemental analysis. The NMR spectra were recorded on a Bruker Avance 500,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
5
00 MHz or 600, 600 MHz for H NMR and Bruker Avance 500, 126 MHz or 600, 151 MHz
13
for C NMR. The spectra were all recorded in dimethyl sulfoxideꢀd (DMSOꢀd ) or
6
6
chloroformꢀd (CDCl3).
The chemical shifts are indicate in δ values (ppm) with the solvent peak as an internal
standard. The resonance peaks multiplicity is displayed as singlet (s), doublet (d), triplet (t),
13
quartet (q) and multiplet (m). The C signals (coupling constant J are in hertz) were
performed with the help of distortionless enhancement by polarization transfer (DEPT) and
attached proton test (APT). The purity of all biologically evaluated compounds was
determined to be > 95% by elemental analysis with Vario EL of Elementar. The results were
all within ± 0.4% of the theoretical values, if not indicated otherwise. Melting points (mp)
were determined with SMP10 (Stuart Scientific)
General procedure for the synthesis of 1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines and 1,6ꢀ
substitutedꢀtetrahydroꢀβꢀcarbolines (1ꢀ20). The tryptamine (1.0 eqiv) derivatives and the
appropriate aldehyde (1.2 eqiv) were dissolved in DCM (2mL/mmol).
TFA was added to the solution and the reaction mixture was stirred for 24 h at room
temperature (rt). After completion of the reaction as indicated by TLC the solution was
evaporated under reduced pressure. The residual was mixed with a 5% K CO aqueous
2
3
solution (3 mL/mmol) and extracted with DCM. The organic layer was dried over magnesium
sulfate and evaporated under reduced pressure to get the crude product that was recrystallized
from ethanol.
11
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 12 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
When the product was already precipitating from DCM, the suspension was filtered off and
washed 5% K CO aqueous solution and DCM. This product was used without further
2
3
purification.
ꢀIsobutylꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (1)
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
The title compound was synthesized from tryptamine (7.5 mmol) and isovaleraldehyde (9
1
mmol), yield 92%, white powder. H NMR (500 MHz, DMSOꢀd6) δ 11.10 (s, 1H), 9.25 (s,
1H), 7.51 – 7.32 (m, 2H), 7.15 – 6.97 (m, 2H), 4.70 (d, J = 8.6 Hz, 1H), 3.59 (dt, J = 12.3, 4.6
Hz, 1H), 3.40 – 3.32 (m, 1H), 3.00 – 2.86 (m, 2H), 2.05 – 1.89 (m, 2H), 1.75 (t, J = 10.2 Hz,
1
3
1
H), 1.00 (dd, J = 25.3, 6.0 Hz, 6H). C NMR (126 MHz, DMSOꢀd6) δ 136.39, 130.72,
126.00, 121.86, 119.16, 118.12, 111.51, 105.76, 50.79, 41.08, 41.02, 23.53(2C), 21.40, 18.34.
15,19
1ꢀPhenylꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (2)
The title compound was synthesized from tryptamine (5 mmol) and benzaldehyde (6 mmol),
1
yield 48%, pale beige powder. H NMR (500 MHz, DMSOꢀd6) δ 10.38 (s, 1H), 7.40 (d, J =
7.7 Hz, 1H), 7.34 – 7.30 (m, 2H), 7.29 – 7.25 (m, 3H), 7.22 (dt, J = 8.0, 0.9 Hz, 1H), 7.03 –
6.96 (m, 1H), 6.98 – 6.90 (m, 1H), 5.08 (s, 1H), 3.06 (dt, J = 12.1, 5.3 Hz, 1H), 2.97 – 2.88
13
(
m, 1H), 2.77 – 2.61 (m, 3H). C NMR (126 MHz, DMSOꢀd ) δ 143.39, 136.08, 135.50,
6
128.54 (2C), 128.20 (2C), 127.25, 127.01, 120.58, 118.27, 117.61, 111.16, 108.41, 56.71,
41.32, 22.40. Anal. Calcd for C17 : C, 82.22; H, 6.49; N, 11.28. Found: C, 82.01; H,
16 2
H N
6.54; N, 11.06.
15
1ꢀ(3ꢀMethoxyphenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (3)
The title compound was synthesized from tryptamine (10 mmol) and 3ꢀmethoxybenzaldehyde
1
(12 mmol), yield 72%, pale yellow powder. H NMR (500 MHz, DMSOꢀd6) δ 10.36 (s, 1H),
7.40 (d, J = 7.6 Hz, 1H), 7.26 – 7.20 (m, 2H), 7.02 – 6.91 (m, 2H), 6.89 – 6.82 (m, 3H), 5.05
(s, 1H), 3.72 (d, J = 4.7 Hz, 3H), 3.11 – 3.04 (m, 1H), 2.97 – 2.89 (m, 1H), 2.77 – 2.61 (m,
12
ACS Paragon Plus Environment

Page 13 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
3
3H). C NMR (126 MHz, DMSOꢀd ) δ 159.33, 144.91, 136.06, 135.47, 129.21, 126.99,
6
1
20.75, 120.59, 118.28, 117.62, 114.34, 112.59, 111.17, 108.27, 56.75, 55.12, 41.47, 22.35.
Anal. Calcd for C18 O: C, 77.67; H, 6.52; N, 10.06. Found: C, 77.96; H, 6.59; N, 10.02.
18 2
H N
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
ꢀ(4ꢀMethoxyphenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (4)
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀmethoxybenzaldehyde
1
(6 mmol), yield: 45%, pale yellow powder. H NMR (500 MHz, DMSOꢀd ) δ 10.86 (s, 1H),
6
9.48 (s, 1H), 7.52 (d, J = 7.9 Hz, 1H), 7.33 – 7.24 (m, 3H), 7.14 – 7.07 (m, 1H), 7.06 – 7.01
(m, 3H), 5.89 (s, 1H), 3.48 – 3.39 (m, 2H), 3.30 (s, 3H), 3.14 – 3.04 (m, 1H), 3.04 – 2.89 (m,
1
3
1H). C NMR (126 MHz, DMSOꢀd
6
) δ 160.48, 136.65, 131.36 (2C), 128.87, 126.72, 125.83,
122.08, 119.17, 118.30, 114.37 (2C), 111.66, 107.39, 55.50, 55.32, 18.37, one peak is
13
missing. C NMR (151 MHz, CDCl3) δ 161.04, 136.43, 131.22(2C), 127.35, 126.03, 125.10,
123.24, 120.28, 118.66, 114.62(2C), 111.35, 108.98, 56.15, 55.38, 40.38, 18.46.
1ꢀ(3,4ꢀDimethoxyphenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (5)
The title compound was synthesized from tryptamine (5 mmol) and 3,4ꢀ
1
dimethoxybenzaldehyde (6 mmol), yield 84%, pale yellow powder. H NMR (500 MHz,
DMSOꢀd
6
) δ 10.82 (s, 1H), 9.36 (s, 1H), 7.51 (d, J = 7.9 Hz, 1H), 7.29 (dt, J = 8.1, 0.9 Hz,
H), 7.14 – 6.99 (m, 4H), 6.82 (dd, J = 8.3, 2.1 Hz, 1H), 5.82 (s, 1H), 3.77 (s, 3H), 3.73 (s,
H), 3.46 (dt, J = 12.5, 5.5 Hz, 1H), 3.44 – 3.34 (m, 1H), 3.13 – 3.03 (m, 1H), 3.03 – 2.93 (m,
1
3
1
1
13
H). C NMR (126 MHz, DMSOꢀd ) δ 150.01, 148.96, 136.63, 129.27, 127.38, 125.92,
6
22.42, 121.99, 119.11, 118.28, 113.38, 111.88, 111.66, 107.38, 55.86, 55.82, 55.73, 40.37,
18.60.
1ꢀ(pꢀTolyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (6)
13
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 14 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀmethylbenzaldehyde (6
1
mmol), yield 43%, beige powder. H NMR (500 MHz, DMSOꢀd ) δ 10.32 (s, 1H), 7.42 – 7.37
6
(m, 1H), 7.21 (dd, J = 7.9, 1.1 Hz, 1H), 7.14 (q, J = 8.0 Hz, 4H), 7.01 – 6.91 (m, 2H), 5.03 (s,
1H), 3.06 (dt, J = 12.2, 5.2 Hz, 1H), 2.96 – 2.86 (m, 1H), 2.75 – 2.58 (m, 3H), 2.28 (s, 3H).
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
3
C NMR (126 MHz, DMSOꢀd
6
) δ 140.38, 136.33, 136.06, 135.75, 128.76 (2C), 128.45 (2C),
127.03, 120.53, 118.25, 117.58, 111.15, 108.28, 56.52, 41.44, 22.42, 20.83.
3ꢀ(2,3,4,9ꢀTetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ1ꢀyl)benzonitrile (7)
The title compound was synthesized from tryptamine (5 mmol) and 3ꢀformylbenzonitrile (6
1
mmol), yield 18%, pale yellow powder. H NMR (500 MHz, DMSOꢀd
6
) δ 10.43 (s, 1H), 7.77
–
7.70 (m, 2H), 7.63 (dt, J = 7.9, 1.5 Hz, 1H), 7.53 (t, J = 7.7 Hz, 1H), 7.42 (dd, J = 7.8, 1.1
Hz, 1H), 7.22 (dt, J = 8.0, 1.0 Hz, 1H), 7.05 – 6.97 (m, 1H), 6.99 – 6.92 (m, 1H), 5.16 (d, J =
1
3
1
.7 Hz, 1H), 3.07 – 2.91 (m, 3H), 2.79 – 2.69 (m, 1H), 2.70 – 2.61 (m, 1H) C NMR (126
MHz, DMSOꢀd ) δ 145.01, 136.13, 134.51, 133.42, 132.08, 131.13, 129.52, 126.91, 120.88,
119.07, 118.45, 117.80, 111.19, 111.16, 108.74, 55.92, 41.36, 22.21.
6
1ꢀ(3ꢀNitrophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (8)
The title compound was synthesized from tryptamine (5 mmol) and 3ꢀnitrobenzaldehyde (6
1
mmol), yield 60%, yellow powder. H NMR (500 MHz, DMSOꢀd
6
) δ 10.94 (s, 1H), 9.85 (s,
1
7
2
1
H), 8.37 – 8.34 (m, 1H), 8.33 – 8.29 (m, 1H), 7.83 – 7.75 (m, 2H), 7.56 (d, J = 7.9 Hz, 1H),
.32 – 7.27 (m, 1H), 7.17 – 7.10 (m, 1H), 7.09 – 7.04 (m, 1H), 6.18 (s, 1H), 3.55 – 3.40 (m,
1
3
H), 3.18 – 3.09 (m, 1H), 3.04 (dt, J = 10.3, 5.5 Hz, 1H) C NMR (126 MHz, DMSOꢀd ) δ
6
47.96, 136.91, 136.73, 136.70, 130.65, 127.74, 125.79, 124.97, 124.77, 122.39, 119.37,
118.51, 111.75, 108.00, 54.86, 40.41, 18.36.
Nꢀ(4ꢀ(2,3,4,9ꢀTetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ1ꢀyl)phenyl)acetamide (9)
14
ACS Paragon Plus Environment

Page 15 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀacetamidobenzaldehyde
1
(
6 mmol), yield 82%, beige powder. H NMR (500 MHz, DMSOꢀd ) δ 10.78 (s, 1H), 10.10
6
(s, 1H), 7.66 – 7.61 (m, 2H), 7.52 – 7.48 (m, 1H), 7.30 – 7.24 (m, 3H), 7.13 – 7.05 (m, 1H),
7.06 – 6.99 (m, 1H), 5.74 (d, J = 2.0 Hz, 1H), 3.41 – 3.29 (m, 3H), 3.08 – 2.99 (m, 1H), 2.98 –
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
3
2
6
.92 (m, 1H), 2.04 (s, 3H). C NMR (126 MHz, DMSOꢀd ) δ 168.65, 140.42, 136.58,
130.40, 130.19 (2C), 129.78, 126.02, 121.86, 119.19 (2C), 119.04, 118.21, 111.60, 107.56,
5
5.56, 40.25, 24.13, 18.99.
1
ꢀ(4ꢀ(Trifluoromethyl)phenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (10)
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀ
1
(
trifluoromethyl)benzaldehyde (6 mmol), yield 97%, white powder. H NMR (500 MHz,
DMSOꢀd ) δ 10.90 (s, 1H), 9.73 (s, 1H), 7.87 (d, J = 8.1 Hz, 2H), 7.62 (d, J = 8.0 Hz, 2H),
6
7
.55 (d, J = 7.9 Hz, 1H), 7.30 (d, J = 8.1 Hz, 1H), 7.13 (t, J = 7.6 Hz, 1H), 7.06 (t, J = 7.4 Hz,
H), 6.08 (s, 1H), 3.53 – 3.40 (m, 2H), 3.12 (dt, J = 13.0, 6.3 Hz, 1H), 3.03 (dt, J = 16.1, 5.6
1
13
Hz, 1H). C NMR (126 MHz, DMSOꢀd
6
) δ 139.1, 136.6, 130.9 (2C), 130.12 (q, J = 32.1 Hz),
27.7, 125.71 (d, J = 3.4 Hz, 2C), 125.6, 123.95 (q, J = 272.4 Hz), 122.1, 119.1, 118.3, 111.5,
07.6, 54.9, 40.2, 18.2.
1
1
1ꢀ(2ꢀFluorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (11)
The title compound was synthesized from tryptamine (5 mmol) and 2ꢀfluorobenzaldehyde (6
1
mmol), yield 32%, light beige powder. H NMR (500 MHz, DMSOꢀd ) δ 10.94 (s, 1H), 9.72
6
(
s, 1H), 7.60 – 7.51 (m, 2H), 7.45 – 7.37 (m, 1H), 7.32 – 7.23 (m, 2H), 7.16 – 7.10 (m, 2H),
7
.10 – 7.02 (m, 1H), 6.16 (s, 1H), 3.58 – 3.49 (m, 1H), 3.48 – 3.40 (m, 1H), 3.17 – 3.07 (m,
13
1H), 3.07 – 2.97 (m, 1H). C NMR (126 MHz, DMSOꢀ d
6
) δ 160.77 (d, J = 249.1 Hz),
1
36.64, 132.38 (d, J = 8.5 Hz), 131.46, 127.48, 125.74, 125.06, 122.25, 121.89 (d, J = 13.2
Hz), 119.25, 118.37, 116.12 (d, J = 21.2 Hz), 111.67, 107.82, 48.88, 40.17, 18.30.
15
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 16 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
ꢀ(4ꢀFluorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (12)
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀfluorobenzaldehyde (6
1
mmol), yield 76%, white powder. H NMR (500 MHz, DMSOꢀ d
6
) δ 10.89 (s, 1H), 9.62 (s,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1H), 7.56 – 7.49 (m, 1H), 7.48 – 7.39 (m, 2H), 7.37 – 7.26 (m, 3H), 7.16 – 7.08 (m, 1H), 7.09
– 7.01 (m, 1H), 5.98 (s, 1H), 3.49 – 3.39 (m, 2H), 3.16 – 3.05 (m, 1H), 3.06 – 2.96 (m, 1H).
1
3
C NMR (126 MHz, DMSOꢀ d ) δ 163.00 (d, J = 246.6 Hz), 136.68, 132.37 (d, J = 8.7 Hz,
6
2
C), 131.06 (d, J = 2.7 Hz), 128.36, 125.77, 122.20, 119.24, 118.37, 115.89 (d, J = 21.8 Hz,
C), 111.68, 107.57, 54.94, 40.11, 18.30.
2
1
ꢀ(3,4ꢀDifluorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (13)
The title compound was synthesized from tryptamine (10 mmol) and 3,4ꢀ
1
difluorobenzaldehyde (12 mmol), yield 91%, pale yellow powder. H NMR (500 MHz,
DMSOꢀd
6
) δ 10.92 (s, 1H), 9.75 (s, 1H), 7.62 – 7.51 (m, 2H), 7.52 – 7.44 (m, 1H), 7.30 (d, J =
8.1 Hz, 1H), 7.26 – 7.21 (m, 1H), 7.17 – 7.09 (m, 1H), 7.08 – 7.02 (m, 1H), 5.99 (s, 1H), 3.52
1
3
–
3.40 (m, 2H), 3.10 (dt, J = 11.9, 5.9 Hz, 1H), 3.01 (dt, J = 16.0, 5.6 Hz, 1H) C NMR (126
MHz, DMSOꢀd ) δ 149.39 (dd, J = 249.2, 12.2 Hz), 148.45 (dd, J = 240.2, 12.8 Hz) , 136.72,
6
132.36, 127.91, 127.39, 125.76, 122.33, 119.31, 119.31 (d, J = 18.0 Hz) 118.47, 111.72,
118.11 (d, J = 17.4 Hz), 107.77, 54.63, 40.19, 18.29.
1ꢀ(2ꢀBromophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (14)
The title compound was synthesized from tryptamine (6.25 mmol) and 2ꢀbromobenzaldehyde
1
(7.5 mmol), yield 56%, white crystals. H NMR (500 MHz, DMSOꢀ d
6
) δ 10.95 (s, 1H), 9.65
(s, 1H), 7.89 – 7.79 (m, 1H), 7.55 (dd, J = 7.7, 1.0 Hz, 1H), 7.47 – 7.38 (m, 2H), 7.29 (dt, J =
8
.1, 1.0 Hz, 1H), 7.19 – 6.99 (m, 3H), 6.15 (s, 1H), 3.60 – 3.51 (m, 1H), 3.43 – 3.34 (m, 1H),
13
3
.18 – 3.09 (m, 1H), 3.05 – 2.96 (m, 1H). C NMR (126 MHz, DMSOꢀ d ) δ 136.71, 133.89,
6
16
ACS Paragon Plus Environment

Page 17 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
133.50, 132.05, 131.77, 128.47, 127.62, 125.65, 125.18, 122.36, 119.29, 118.44, 111.69,
108.06, 54.82, 39.78, 18.33.
1ꢀ(4ꢀBromophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (15)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The title compound was synthesized from tryptamine (7.5 mmol) and 4ꢀbromobenzaldehyde
1
(9 mmol), yield 33%, white powder. H NMR (500 MHz, DMSOꢀd ) δ 10.88 (s, 1H), 9.64 (s,
6
1
8
3
H), 7.73 – 7.67 (m, 2H), 7.53 (dd, J = 7.7, 1.0 Hz, 1H), 7.36 – 7.31 (m, 2H), 7.29 (dt, J =
.1, 1.0 Hz, 1H), 7.16 – 7.09 (m, 1H), 7.08 – 7.01 (m, 1H), 5.96 (s, 1H), 3.48 – 3.39 (m, 2H),
13
6
.14 – 3.06 (m, 1H), 3.05 – 2.97 (m, 1H). C NMR (126 MHz, DMSOꢀd ) δ 136.70, 134.11,
132.21 (2C), 131.96 (2C), 128.10, 125.76, 123.45, 122.25, 119.27, 118.39, 111.69, 107.63,
55.07, 40.21, 18.31.
1ꢀ(2ꢀChlorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (16)
The title compound was synthesized from tryptamine (5 mmol) and 2ꢀchlorobenzaldehyde (6
1
mmol), yield 56%, pale beige powder. H NMR (500 MHz, DMSOꢀd
6
) δ 10.95 (s, 1H), 9.67
(
s, 1H), 7.68 (dd, J = 8.1, 1.2 Hz, 1H), 7.58 – 7.49 (m, 2H), 7.38 (td, J = 7.6, 1.3 Hz, 1H), 7.29
dt, J = 8.1, 1.0 Hz, 1H), 7.16 – 7.07 (m, 2H), 7.09 – 7.02 (m, 1H), 6.21 (d, J = 1.5 Hz, 1H),
.55 (dt, J = 12.1, 5.8 Hz, 1H), 3.44 – 3.35 (m, 1H), 3.17 – 3.09 (m, 1H), 3.07 – 2.97 (m, 1H)
(
3
1
3
6
C NMR (126 MHz, DMSOꢀd ) δ 136.70, 134.34, 132.37, 131.80, 131.67, 130.17, 127.92,
127.64, 125.70, 122.33, 119.28, 118.43, 111.70, 108.11, 52.18, 39.92, 18.37.
1ꢀ(3ꢀChlorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (17)
The title compound was synthesized from tryptamine (5 mmol) and 3ꢀchlorobenzaldehyde (6
1
mmol), yield 80%, pale yellow powder. H NMR (500 MHz, DMSOꢀd
6
) δ 10.92 (s, 1H), 9.66
(s, 1H), 7.59 – 7.47 (m, 4H), 7.34 – 7.28 (m, 2H), 7.16 – 7.09 (m, 1H), 7.09 – 7.02 (m, 1H),
13
5
.98 (s, 1H), 3.52 – 3.37 (m, 2H), 3.16 – 3.06 (m, 1H), 3.01 (dt, J = 10.3, 5.6 Hz, 1H). C
17
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 18 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
NMR (126 MHz, DMSOꢀd ) δ 137.22, 136.70, 133.53, 130.92, 129.90, 129.84, 128.74,
6
127.97, 125.77, 122.29, 119.29, 118.44, 111.72, 107.77, 55.08, 40.30, 18.34.
1ꢀ(4ꢀChlorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (18)
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
The title compound was synthesized from tryptamine (5 mmol) and 4ꢀchlorobenzaldehyde(6
1
mmol), yield 37%, yellow powder. H NMR (500 MHz, DMSOꢀd ) δ 10.89 (s, 1H), 9.64 (s,
6
1
1
3
H), 7.59 – 7.51 (m, 3H), 7.42 – 7.38 (m, 2H), 7.29 (dt, J = 8.1, 1.0 Hz, 1H), 7.16– 7.08 (m,
H), 7.08 – 7,01 (m, 1H), 5.98 (s, 1H), 3.44 (td, J = 7.0, 6.4, 4.3 Hz, 2H), 3.15 – 3.05 (m, 1H),
13
6
.06 – 2.97 (m, 1H). C NMR (126 MHz, DMSOꢀd ) δ 136.70, 134.75, 133.71, 131.95 (2C),
129.02 (2C), 128.15, 125.76, 122.25, 119.28, 118.40, 111.69, 107.63, 54.99, 40.21, 18.31.
1ꢀ(3,4ꢀDichlorophenyl)ꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (19)
The title compound was synthesized from tryptamine (15 mmol) and 3,4ꢀ
1
dichlorobenzaldehyde (18 mmol), yield 51%, beige powder. H NMR (500 MHz, DMSOꢀd
6
)
δ 10.90 (s, 1H), 9.71 (s, 1H), 7.77 (d, J = 8.4 Hz, 1H), 7.69 (d, J = 2.1 Hz, 1H), 7.54 (d, J =
7.8 Hz, 1H), 7.36 – 7.27 (m, 2H), 7.13 (td, J = 8.2, 7.6, 1.3 Hz, 1H), 7.09 – 7.03 (m, 1H), 6.00
13
(
s, 1H), 3.54 – 3.39 (m, 2H), 3.15 – 3.06 (m, 1H), 3.06 – 2.95 (m, 1H). C NMR (126 MHz,
DMSOꢀd
6
) δ 136.70, 135.63, 132.76, 132.11, 131.55, 131.18, 130.33, 127.69, 125.73, 122.38,
119.35, 118.48, 111.72, 107.83, 54.57, 40.42, 18.29.
1ꢀ(3,4ꢀDichlorophenyl)ꢀ6ꢀmethoxyꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indole (20)
The title compound was synthesized from 5ꢀmethoxytryptamine (1.8 mmol) and 3,4ꢀ
1
dichlorobenzaldehyde (2.16 mmol), yield 45%, white powder. H NMR (500 MHz, DMSOꢀ
d
6
) δ 10.72 (s, 1H), 9.68 (s, 1H), 7.76 (d, J = 8.3 Hz, 1H), 7.67 (d, J = 2.1 Hz, 1H), 7.32 (dd, J
8.3, 2.2 Hz, 1H), 7.19 (d, J = 8.7 Hz, 1H), 7.04 (d, J = 2.5 Hz, 1H), 6.77 (dd, J = 8.8, 2.5
=
Hz, 1H), 5.97 (s, 1H), 3.77 (s, 3H), 3.52 – 3.38 (m, 2H), 3.07 (dt, J = 13.3, 6.3 Hz, 1H), 3.02 –
18
ACS Paragon Plus Environment

Page 19 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
3
2.93 (m, 1H). C NMR (126 MHz, DMSOꢀd ) δ 153.73, 135.70, 132.73, 132.07, 131.74,
6
1
31.54, 131.17, 130.30, 128.22, 126.09, 112.43 (2C), 107.60, 100.47, 55.60, 54.64, 40.46,
8.36.
1
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
General procedure for the synthesis of N2ꢀacylꢀ1ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines and N2ꢀ
acylꢀ1,6ꢀsubstitutedꢀtetrahydroꢀβꢀcarbolines (21ꢀ53) Under stirring at 0° the desired benzoyl
chloride (1.1 equiv) was added slowly to a mixture of the appropriate compound (1ꢀ20) (1
equiv) and TEA (1.2 equiv) in dry THF (10 ml/mmol). The mixture was stirred for 1 h at 0°
and then 12 h at rt. After completion of the reaction as indicated by TLC the precipated TEAꢀ
hydrochloride was removed by filtration. The clear solution was evaporated under reduce
pressure to get the crude product, that was recrystallized from ethanol or ethanol/THF (9:1).
(1ꢀIsobutylꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (21)
The title compound was synthesized from 1 (2.19 mmol) and benzoylchloride (2.41 mmol),
1
yield 21%, white crystals, mp 188ꢀ189 °C. H NMR (500 MHz, DMSOꢀ d
6
) δ 10.93 (s, 1H),
7
6
3
.50 – 7.45 (m, 3H), 7.40 – 7.36 (m, 2H), 7.33 (dd, J = 14.3, 7.9 Hz, 2H), 7.08 – 7.01 (m, 1H),
.98 – 6.91 (m, 1H), 5.85 (dd, J = 10.5, 3.7 Hz, 1H), 3.70 (dd, J = 13.6, 4.6 Hz, 1H), 3.53 –
.41 (m, 1H), 2.67 – 2.54 (m, 2H), 1.90 – 1.77 (m, 2H), 1.74 – 1.69 (m, 1H), 1.10 (d, J = 6.3
1
3
Hz, 3H), 0.99 (d, J = 6.4 Hz, 3H). C NMR (126 MHz, DMSO d
6
) δ 170.30, 137.08, 136.05,
35.23, 129.37, 128.70(2C), 126.48, 126.29(2C), 120.97, 118.61, 117.69, 111.20, 105.86,
6.94, 43.43, 41.07, 24.94, 23.69, 22.46, 22.04.
1
4
Anal. Calcd for C H N O: C, 79.48; H, 7.28; N, 8.43. Found: C, 79.17; H, 7.67; N, 8.02.
2
2
24
2
1
9
Phenyl(1ꢀphenylꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)methanone (22)
The title compound was synthesized from 2 (1 mmol) and benzoylchloride (1.1 mmol), yield
1
6
3%, whiteꢀbeige crystals, mp 238ꢀ239 °C. H NMR (600 MHz, DMSOꢀd ) δ 11.05 (s, 1H),
6
19
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 20 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
7.47 (d, J = 5.9 Hz, 4H), 7.42 – 7.28 (m, 8H), 7.09 (t, J = 7.0 Hz, 1H), 7.01 (t, J = 7.2 Hz,
1H), 6.96 (s, 1H), 3.64 (d, J = 8.4 Hz, 1H), 3.26 (d, J = 11.7 Hz, 1H), 2.86 (t, J = 10.8 Hz,
13
1
H), 2.74 (d, J = 15.2 Hz, 1H). C NMR (151 MHz, DMSOꢀd
6
) δ 169.71, 140.42, 136.39
(
2C), 131.58, 129.65, 128.71 (2C), 128.66 (2C), 128.14, 127.96 (2C), 126.43 (2C), 126.32,
21.47, 118.79, 118.05, 111.38, 108.12, 51.65, 41.30, 21.83 Anal. Calcd for C24 O: C,
81.79; H, 5.72; N, 7.95. Found: C, 81.69; H, 5.48; N, 7.58.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
.
20 2
H N
(1ꢀ(3ꢀMethoxyphenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (23)
The title compound was synthesized from 3 (1.08 mmol) and benzoylchloride (1.18 mmol),
1
yield 77%, pale beige powder, mp 222ꢀ223 °C. H NMR (600 MHz, DMSOꢀd
6
) δ 11.04 (s,
1H), 7.54 – 7.36 (m, 7H), 7.34 – 7.24 (m, 2H), 7.09 (t, J = 7.7 Hz, 1H), 7.01 (t, J = 7.4 Hz,
1H), 6.90 (d, J = 14.5 Hz, 3H), 3.72 (s, 3H), 3.65 (d, J = 11.7 Hz, 1H), One signal is missing
1
(
CH
2
) under the water peak, 2.84 (d, J = 13.0 Hz, 1H), 2.74 (d, J = 15.5 Hz, 1H). H NMR
(
600 MHz, CDCl
3
) δ 8.11 (s, 1H), 7.51 (d, J = 7.8 Hz, 1H), 7.44 – 7.35 (m, 5H), 7.28 (d, J =
8.1 Hz, 1H), 7.23 – 7.15 (m, 2H), 7.15 – 7.10 (m, 1H), 7.08 (s, 1H), 7.01 (s, 1H), 6.95 (d, J =
7.6 Hz, 1H), 6.83 (d, J = 8.2 Hz, 1H), 3.78 (d, J = 13.3 Hz, 1H), 3.74 (s, 3H), 3.40 (t, J = 12.5
13
Hz, 1H), 2.97 – 2.86 (m, 1H), 2.77 (d, J = 15.3 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ
6
169.77, 159.55, 141.97, 136.42 (2C), 131.56, 129.77, 129.70, 128.76 (2C), 126.47 (2C),
126.32, 121.52, 120.31, 118.83, 118.11, 114.36, 112.96, 111.41, 108.13, 55.22, 51.63, 41.48,
2
1.85. Anal. Calcd for C25
.34.
22 2 2
H N O : C, 78.51; H, 5.80; N, 7.32. Found: C, 78.48; H, 5.92; N,
7
19
(1ꢀ(4ꢀMethoxyphenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (24)
The title compound was synthesized from 4 (1.0 mmol) and benzoylchloride (1.1 mmol),
1
yield 29%, white crystals, mp 182ꢀ183 °C. H NMR (600 MHz, DMSOꢀd
6
) δ 11.00 (s, 1H),
7.50 – 7.44 (m, 4H), 7.40 – 7.35 (m, 2H), 7.27 (dd, J = 46.7, 7.3 Hz, 3H), 7.09 (t, J = 7.3 Hz,
20
ACS Paragon Plus Environment

Page 21 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1H), 7.03 – 6.99 (m, 1H), 6.96 – 6.87 (m, 3H), 3.73 (s, 3H), 3.62 (d, J = 9.1 Hz, 1H), 3.27 (s,
1
3
1
1
1
H), 2.85 (s, 1H), 2.74 (d, J = 14.8 Hz, 1H). C NMR (151 MHz, DMSOꢀd ) δ 169.60,
6
59.05, 136.53, 136.41, 132.55, 131.97, 129.64, 129.47 (2C), 128.73 (2C), 126.44 (2C),
26.37, 121.44, 118.78, 118.05, 114.03 (2C), 111.37, 108.06, 55.28, 51.18, 41.11, 21.89.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
22 2 2
Anal. Calcd for C25H N O : C, 78.51; H, 5.80; N, 7.32. Found: C, 78.62; H, 5.82; N, 7.29.
(1ꢀ(3,4ꢀDimethoxyphenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone
20
(25)
The title compound was synthesized from 5 (1.3 mmol) and benzoylchloride (1.43 mmol),
1
yield 30%, white crystals, mp 238ꢀ239 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.01 (s, 1H),
7
7
8
1
.47 (dd, J = 7.2, 4.1 Hz, 4H), 7.39 (dd, J = 6.4, 3.2 Hz, 2H), 7.32 (d, J = 7.7 Hz, 1H), 7.11 –
.03 (m, 2H), 7.01 (td, J = 7.5, 1.0 Hz, 1H), 6.91 (d, J = 8.3 Hz, 2H), 6.68 (s, 1H), 3.72 (d, J =
.2 Hz, 6H), 3.66 – 3.57 (m, 1H), one signal is missing (CH
2
) under the water peak, 2.85 (s,
1
H), 2.74 (d, J = 13.4 Hz, 1H). H NMR (600 MHz, CDCl
3
) δ 8.27 (s, 1H), 7.52 (d, J = 7.8
Hz, 1H), 7.45 – 7.36 (m, 5H), 7.29 (d, J = 8.1 Hz, 1H), 7.21 – 7.15 (m, 2H), 7.15 – 7.10 (m,
1
1
1
H), 7.03 (s, 1H), 6.70 (t, J = 7.2 Hz, 2H), 3.82 (s, 3H), 3.78 (s, 4H), 3.38 (t, J = 12.0 Hz,
13
H), 2.92 (d, J = 10.6 Hz, 1H), 2.78 (d, J = 14.7 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ
6
69.67, 148.97, 148.79, 136.55, 136.42, 132.97, 131.86, 129.62, 128.73 (2C), 126.44 (2C)
126.32, 121.44, 120.57, 118.76, 118.06, 112.10, 111.70, 111.36, 108.11, 55.71 (2C), 51.47,
4
1.25, 21.91. Anal. Calcd for C26
.95; N, 6.35.
24 2 3
H N O : C, 75.71; H, 5.86; N, 6.79. Found: C, 75.96; H,
5
1
9
Phenyl(1ꢀ(pꢀtolyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)methanone (26)
The title compound was synthesized from 6 (1.14 mmol) and benzoylchloride (1.25 mmol),
1
yield 34%, white powder, mp 207ꢀ208 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.00 (s, 1H),
7.46 (dt, J = 7.4, 3.0 Hz, 4H), 7.40 – 7.36 (m, 2H), 7.32 (d, J = 7.9 Hz, 1H), 7.19 (t, J = 8.0
21
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 22 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Hz, 4H), 7.11 – 7.06 (m, 1H), 7.03 – 6.98 (m, 1H), 6.92 (s, 1H), 3.62 (d, J = 9.9 Hz, 1H), 3.24
1
3
(
d, J = 19.8 Hz, 1H), 2.85 (s, 1H), 2.73 (d, J = 14.1 Hz, 1H), 2.29 (s, 3H). C NMR (126
MHz, DMSOꢀd ) δ 169.64, 137.53, 137.25, 136.50, 136.42, 131.83, 129.63, 129.19(2),
28.73(2), 128.14(2), 126.43(2), 126.37, 121.44, 118.79, 118.04, 111.38, 108.07, 51.43,
1.23, 21.88, 20.79.
6
1
4
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Anal. Calcd for C H N O: C, 81.94; H, 6.05; N, 7.64. Found: C, 82.09; H, 5.94; N, 7.74.
2
5
22
2
3ꢀ(2ꢀBenzoylꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ1ꢀyl)benzonitrile (27)
The title compound was synthesized from 7 (0.84 mmol) and benzoylchloride (0.92 mmol),
1
yield 73%, white powder, mp 231ꢀ234 °C (decomposition). H NMR (500 MHz, DMSOꢀd
6
) δ
1
1.00 (s, 1H), 7.83 (d, J = 7.5 Hz, 1H), 7.70 (d, J = 14.2 Hz, 2H), 7.62 (t, J = 7.7 Hz, 1H),
.51 – 7.45 (m, 4H), 7.44 (s, 2H), 7.35 (d, J = 8.0 Hz, 1H), 7.15 – 7.08 (m, 1H), 7.06 – 6.99
7
(m, 1H), 6.93 (s, 1H), 3.69 (s, 1H), 3.32 (d, J = 9.9 Hz, 1H), 2.87 (d, J = 10.9 Hz, 1H), 2.78
13
(
6
d, J = 12.5 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ 170.12, 141.87, 136.50, 136.06,
132.92, 131.85, 131.54, 130.53, 130.09, 129.83, 128.71 (2C), 126.57 (2C), 126.24, 121.73,
18.94, 118.74, 118.21, 111.67, 111.51, 108.69, 51.41, 41.73, 21.63. Anal. Calcd for
C H N O: C, 79.55; H, 5.07; N, 11.13. Found: C, 79.37; H, 5.19; N,11.03.
1
25
19
3
(1ꢀ(3ꢀNitrophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (28)
The title compound was synthesized from 8 (1.02 mmol) and benzoylchloride (1.12 mmol),
1
yield 39%, yellow powder, mp 284ꢀ286 °C (decomposition). H NMR (500 MHz, DMSOꢀd )
6
δ 11.05 (s, 1H), 8.22 (d, J = 7.8 Hz, 1H), 8.13 (s, 1H), 7.79 (s, 1H), 7.70 (t, J = 7.9 Hz, 1H),
7
.53 – 7.45 (m, 4H), 7.43 (d, J = 6.2 Hz, 2H), 7.36 (d, J = 8.1 Hz, 1H), 7.15 – 7.09 (m, 1H),
7.08 – 6.99 (m, 2H), 3.70 (s, 1H), One signal is missing (CH ) under the water peak, 2.91 (t, J
10.6 Hz, 1H), 2.80 (d, J = 14.0 Hz, 1H). No additional spectrum could be acquired as the
2
=
13
compound is not soluble in CDCl3. C NMR (126 MHz, DMSOꢀd ) δ 170.2, 148.1, 142.5,
6
22
ACS Paragon Plus Environment

Page 23 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
136.6, 136.0, 134.7, 130.5, 130.5, 129.9, 128.8 (2C), 126.6 (2C), 126.3, 123.1, 122.7, 121.9,
1
19.0, 118.3, 111.6, 108.8, 51.4, 41.8, 21.7. Anal. Calcd for C H N O : C, 72.53; H, 4.82;
24 19 3 3
N, 10.57. Found: C, 72.42; H, 4.97; N, 10.48.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Nꢀ(4ꢀ(2ꢀBenzoylꢀ2,3,4,9ꢀtetrahydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ1ꢀyl)phenyl)acetamide (29)
The title compound was synthesized from 9 (1.31 mmol) and benzoylchloride (1.44 mmol),
1
yield 45%, yellowꢀorange powder, mp from 190 °C (decomposition). H NMR (500 MHz,
6
DMSOꢀd ) δ 11.01 (s, 1H), 9.96 (s, 1H), 7.56 (d, J = 8.0 Hz,2H), 7.49 – 7.43 (m, 4H), 7.39 (d,
J = 3.3 Hz, 2H), 7.32 (d, J = 7.6 Hz, 1H), 7.24 (d, J = 7.0 Hz, 2H), 7.11 – 7.06 (m, 1H), 7.04 –
6.97 (m, 1H), 6.90 (s, 1H), 3.63 (d, J = 9.2 Hz, 1H), 3.28 (s, 1H), 2.85 (s, 1H), 2.74 (d, J =
1
3
1
1
1
3.4 Hz, 1H), 2.02 (s, 3H). C NMR (126 MHz, DMSOꢀd ) δ 169.62, 168.37, 139.05,
6
36.48, 136.40, 134.91, 131.82, 129.60, 128.70 (2C), 128.51 (2C), 126.44 (2C), 126.35,
21.41, 119.18 (2C), 118.76, 118.03, 111.37, 108.04, 51.31, 41.21, 24.03, 21.86. Anal. Calcd
23 3
for C26H N O: C, 76.26; H, 5.66; N, 10.26. Found: C, 74.72; H, 5.66; N, 9.94.
Phenyl(1ꢀ(4ꢀ(trifluoromethyl)phenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)methanone
30)
(
The title compound was synthesized from 10 (0.95 mmol) and benzoylchloride (1.04 mmol),
1
yield 58%, white powder, mp 260ꢀ261 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.03 (s, 1H),
7
.76 (d, J = 8.1 Hz, 2H), 7.56 (d, J = 6.5 Hz, 2H), 7.51 – 7.44 (m, 4H), 7.42 (d, J = 5.7 Hz,
H), 7.34 (d, J = 8.1 Hz, 1H), 7.15 – 7.07 (m, 1H), 7.06 – 6.99 (m, 1H), 7.00 (s, 1H), 3.69 (d,
2
13
J = 10.5 Hz, 1H), 3.27 – 3.19 (m, 1H), 2.89 (s, 1H), 2.77 (d, J = 14.5 Hz, 1H). C NMR (126
MHz, DMSOꢀd ) δ 169.83, 144.74, 136.33, 135.97, 130.63, 129.64 (2C), 128.88, 128.58
(2C), 128.16 (d, J = 31.8 Hz), 126.36 (2C), 126.13, 125.49 (d, J = 3.9 Hz, 2C), 124.27 (q, J =
72.3Hz).121.53, 118.78, 118.03, 111.33, 108.38, 51.27, 41.48, 21.58. Anal. Calcd for
6
2
C H F N O: C, 71.42; H, 4.56; N, 6.66. Found: C, 71.61; H, 4.57; N, 6.77.
25
19
3
2
23
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 24 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
1ꢀ(2ꢀFluorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (31)
The title compound was synthesized from 11 (1.12 mmol) and benzoylchloride (1.24 mmol),
1
yield 50 %, white crystals, mp 211ꢀ213 °C. H NMR (500 MHz, DMSOꢀ d
6
) δ 10.92 (s, 1H),
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
13
7
.51 – 6.96 (m, 14H), 3.72 (s, 1H), 3.37 (s, 1H), 2.74 (s, 2H). C NMR (126 MHz, DMSO
d6) δ 169.73, 160.14 (d, J = 248.2 Hz), 136.20 (d, J = 7.8 Hz), 130.70, 130.36, 130.09 (d, J =
.5 Hz), 129.51, 128.48(2C), 126.91 (d, J = 17.0 Hz), 126.43(3C), 126.15,124.19 (d, J = 3.0
Hz), 121.38, 118.67, 117.89, 115.68 (d, J = 21.4 Hz), 111.31, 108.19, 46.34, 41.68, 21.73.
Anal. Calcd for C24 O: C, 77.82; H, 5.17; N,7.56. Found: C, 77.66; H, 5.37; N, 7.50
7
H19FN
2
(1ꢀ(4ꢀFluorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (32)
The title compound was synthesized from 12 (1.88 mmol) and benzoylchloride (2.07 mmol),
1
yield 54%, white crystals, mp 153ꢀ156 °C. H NMR (600 MHz, CDCl
3
) δ 8.16 (s, 1H), 7.52
(d, J = 7.8 Hz, 1H), 7.45 – 7.34 (m, 7H), 7.28 (d, J = 8.1 Hz, 1H), 7.22 – 7.16 (m, 1H), 7.15 –
7.12 (m, 1H), 7.09 (s, 1H), 6.97 (t, J = 8.5 Hz, 2H), 3.82 – 3.73 (m, 1H), 3.39 – 3.27 (m, 1H),
13
2
.93 (s, 1H), 2.84 – 2.73 (m, 1H). C NMR (151 MHz, CDCl ) δ 170.66, 162.54 (d, J = 247.4
3
Hz), 136.34, 136.18, 135.68, 131.06, 130.61 (d, J = 7.0 Hz, 2C), 129.71(2C), 128.56(2C),
26.54, 126.48, 122.36, 119.76, 118.21, 115.42 (d, J = 21.4 Hz, 2C), 111.18, 109.74, 51.55,
41.34, 22.26. Anal. Calcd for C24 O: C, 77.82; H,5.17; N,7.56. Found: C, 77.45; H,
.44; N, 7.28
1
H19FN
2
5
(1ꢀ(3,4ꢀDifluorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (33)
The title compound was synthesized from 13 (1.05 mmol) and benzoylchloride (1.16 mmol),
1
yield 44%, pale pink needles, mp 236ꢀ237 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.01 (s,
1
H), 7.52 – 7.44 (m, 5H), 7.42 (d, J = 8.2 Hz, 2H), 7.34 (d, J = 8.1 Hz, 2H), 7.15 (s, 1H), 7.13
7.09 (m, 1H), 7.04 – 7.00 (m, 1H), 6.89 (s, 1H), 3.67 (s, 1H), One signal is missing (CH2)
–
24
ACS Paragon Plus Environment

Page 25 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
1
under the water peak, 2.87 (t, J = 10.6 Hz, 1H), 2.77 (d, J = 13.4 Hz, 1H). H NMR (600
MHz, CDCl ) δ 8.29 (s, 1H), 7.52 (d, J = 7.8 Hz, 1H), 7.46 – 7.39 (m, 3H), 7.39 – 7.34 (m,
3
2
3
4
H), 7.28 (d, J = 8.2 Hz, 1H), 7.23 – 7.18 (m, 2H), 7.16 – 7.11 (m, 2H), 7.09 – 7.01 (m, 2H),
.79 (dd, J = 14.1, 5.3 Hz, 1H), 3.37 – 3.26 (m, 1H), 2.99 – 2.88 (m, 1H), 2.79 (dd, J = 15.7,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
6
.1 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ 170.01, 148.49 (dd, J = 246.0, 12.7 Hz),
148.19 (dd, J = 247.8, 12.4 Hz),, 138.08, 136.50, 136.13, 130.86, 129.84, 128.75 (2C), 126.58
(
2C), 126.26, 125.00, 121.73, 118.95, 118.23,117.72 (d, J = 17.1 Hz), 117.15 (d, J = 16.6 Hz).
,
111.52, 108.57, 51.05, 41.54, 21.70. Anal. Calcd for C24
.21. Found: C, 73.95; H, 4.84; N, 7.09.
18 2 2
H F N O: C, 74.21; H, 4.67; N,
7
(
1ꢀ(2ꢀBromophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (34)
The title compound was synthesized from 14 (1.53 mmol) and benzoylchloride (1.68 mmol),
1
yield 34%, white powder, mp 268ꢀ273 °C (decomposition). H NMR (500 MHz, DMSOꢀ d
6
)
δ 10.96 (s, 1H), 7.75 (d, J = 5.2 Hz, 1H), 7.51 – 7.38 (m, 6H), 7.34 – 7.27 (m, 3H), 7.13 –
7.06 (m, 1H), 7.06 – 6.97 (m, 2H), 6.82 – 6.78 (m, 1H), 3.68 (s, 1H), 3.27 – 3.19 (m, 1H),
1
3
2
1
1
.70 (d, J = 15.2 Hz, 2H). C NMR (126 MHz, DMSOꢀ d ) δ 171.12, 139.12, 136.29, 136.12,
6
33.45, 131.36, 131.31, 130.08, 130.01, 128.64(2C), 127.63, 127.02(2C), 126.34, 123.70,
2
21.58, 118.85, 118.05, 111.50, 108.51, 51.96, 41.79, 22.12. Anal. Calcd for C24H19BrN O:
C, 66.83; H, 4.44; N, 6.49. Found: C, 66.85; H, 4.51; N, 6.47.
(
1ꢀ(4ꢀBromophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (35)
The title compound was synthesized from 15 (0.83 mmol) and benzoylchloride (0.92 mmol),
1
yield 32%, white powder, mp 236ꢀ237 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.01 (s, 1H),
7.58 (d, J = 8.2 Hz, 2H), 7.50 – 7.44 (m, 4H), 7.40 (d, J = 5.4 Hz, 2H), 7.30 (dd, J = 25.7, 7.4
Hz, 3H), 7.12 – 7.07 (m, 1H), 7.05 – 6.98 (m, 1H), 6.90 (s, 1H), 3.66 (d, J = 9.6 Hz, 1H), 3.27
13
–
3.19 (m, 1H), 2.86 (s, 1H), 2.75 (d, J = 14.4 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ
6
25
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 26 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
169.87, 139.82, 136.47, 136.26, 131.63 (2C), 131.12, 130.43 (2C), 129.77, 128.76 (2C),
126.51 (2C), 126.32, 121.64, 121.26, 118.91, 118.16, 111.47, 108.41, 51.23, 41.41, 21.80.
Anal. Calcd for C24 O: C, 66.83; H, 4.44; N, 6.49. Found: C, 66.76; H, 4.36; N, 6.09.
H19BrN
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1ꢀ(2ꢀChlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (36)
The title compound was synthesized from 16 (1.06 mmol) and benzoylchloride (1.16 mmol),
1
yield 17%, white crystals, mp 276ꢀ278 °C (decomposition). H NMR (500 MHz, DMSOꢀd ) δ
6
10.96 (s, 1H), 7.57 (d, J = 7.1 Hz, 1H), 7.51 – 7.42 (m, 4H), 7.38 (t, J = 6.9 Hz, 3H), 7.32 (dt,
J = 8.1, 0.8 Hz, 1H), 7.26 (td, J = 7.6, 1.1 Hz, 1H), 7.15 (s, 1H), 7.13 – 7.06 (m, 1H), 7.02
(dd, J = 11.0, 3.9 Hz, 1H), 6.82 (dd, J = 7.7, 1.6 Hz, 1H), 3.68 (s, 1H), 3.25 (s, 1H), 2.66 (d, J
13
=
34.5 Hz, 2H). C NMR (126 MHz, DMSOꢀd ) δ 170.80, 137.51, 136.34, 136.22, 133.42,
6
1
31.19, 131.05, 130.08, 129.94, 129.89, 128.68, 127.14 (2C), 126.93 (2C), 126.38, 121.62,
18.89, 118.09, 111.53, 108.66, 49.66, 41.68, 22.10. Anal. Calcd for C24 O: C, 74.51;
1
H19ClN
2
H, 4.95; N, 7.24. Found: C, 74.74; H, 5.16; N, 6.88.
(1ꢀ(3ꢀChlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (37)
The title compound was synthesized from 17 (1.06 mmol) and benzoylchloride (1.17 mmol),
1
yield 27%, pale yellow powder, mp 219ꢀ220 °C. H NMR (600 MHz, DMSOꢀd
6
) δ 11.04 (s,
1H), 7.51 – 7.45 (m, 4H), 7.44 – 7.37 (m, 4H), 7.33 (t, J = 13.7 Hz, 3H), 7.13 – 7.09 (m, 1H),
2
7.04 – 7.00 (m, 1H), 6.91 (s, 1H), 3.68 (d, J = 10.2 Hz, 1H), One signal is missing (CH )
1
under the water peak, 2.86 (d, J = 10.0 Hz, 1H), 2.77 (d, J = 14.2 Hz, 1H). H NMR (600
MHz, CDCl ) δ 8.21 (s, 1H), 7.52 (d, J = 7.8 Hz, 1H), 7.45 – 7.38 (m, 3H), 7.39 – 7.33 (m,
3
4H), 7.30 – 7.25 (m, 2H), 7.24 – 7.18 (m, 2H), 7.14 (td, J = 7.5, 1.0 Hz, 1H), 7.09 (s, 1H),
13
3.83 – 3.75 (m, 1H), 3.39 – 3.30 (m, 1H), 2.93 (t, J = 11.2 Hz, 1H), 2.82 – 2.74 (m, 1H). C
NMR (151 MHz, DMSOꢀd
6
) δ 170.29, 143.16, 136.80, 136.49, 133.69, 131.20, 131.05 (2C),
130.16, 129.10, 128.41, 128.31, 127.19, 126.87 (2C), 126.61, 122.04, 119.28, 118.55, 111.85,
26
ACS Paragon Plus Environment

Page 27 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
108.84, 51.74, 41.92, 22.06
C, 74.24; H, 4.96; N, 7.12.
.
Anal. Calcd for C H ClN O : C, 74.51; H, 4.95; N, 7.24. Found:
24
19
2
2
19
(1ꢀ(4ꢀChlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone (38)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The title compound was synthesized from 18 (1.06 mmol) and benzoylchloride (1.16 mmol),
1
yield 16%, white powder, mp 223ꢀ224 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.02 (s, 1H),
7.51 – 7.42 (m, 6H), 7.36 (dd, J = 35.1, 6.8 Hz, 5H), 7.12 – 7.07 (m, 1H), 7.05 – 6.98 (m,
1H), 6.92 (s, 1H), 3.66 (d, J = 10.2 Hz, 1H), 3.26 – 3.19 (m, 1H), 2.87 (s, 1H), 2.75 (d, J =
1
3
1
1
1
4.7 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ 169.80, 139.35, 136.41, 136.20, 132.62,
6
31.11, 130.01, 129.71 (2C), 128.70 (2C), 128.63 (2C), 126.45 (2C), 126.26, 121.57, 118.8,
2
18.09, 111.41, 108.33, 51.11, 41.34, 21.72. Anal. Calcd for C24H19ClN O: C, 74.51; H, 4.95;
N, 7.24. Found: C, 74.75; H, 5.00; N, 7.40.
(1ꢀ(3,4ꢀDichlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(phenyl)methanone
(39)
The title compound was synthesized from 19 (0.95 mmol) and benzoylchloride (1.04 mmol),
1
yield 40%, white crystals, mp 209ꢀ210 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.00 (s, 1H),
7.66 (d, J = 8.4 Hz, 1H), 7.53 – 7.45 (m, 5H), 7.42 (d, J = 5.7 Hz, 2H), 7.34 (t, J = 9.3 Hz,
2H), 7.15 – 7.08 (m, 1H), 7.06 – 6.99 (m, 1H), 6.88 (s, 1H), 3.68, One signal is missing (CH2)
1
under the water peak, (s, 1H), 2.92 – 2.83 (m, 1H), 2.78 (d, J = 13.1 Hz, 1H). H NMR (600
3
MHz, CDCl ) δ 8.27 (s, 1H), 7.47 (d, J = 7.8 Hz, 1H), 7.41 – 7.34 (m, 4H), 7.32 – 7.27 (m,
3H), 7.26 – 7.20 (m, 2H), 7.18 – 7.12 (m, 1H), 7.12 – 7.06 (m, 1H), 7.00 (s, 1H), 3.74 (d, J =
1
3
1
1.5 Hz, 1H), 3.25 (t, J = 12.5 Hz, 1H), 2.92 – 2.83 (m, 1H), 2.74 (d, J = 15.6 Hz, 1H). C
NMR (126 MHz, DMSOꢀd ) δ 170.05, 141.38, 136.49, 136.04, 131.30, 130.99, 130.75,
6
130.54, 130.08, 129.85, 128.73 (2C), 128.48, 126.56 (2C), 126.22, 121.77, 118.97, 118.23,
27
ACS Paragon Plus Environment

Journal of Medicinal Chemistry
Page 28 of 64
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
111.52, 108.68, 51.04, 41.68, 21.63. Anal. Calcd for C H Cl N O: C, 68.42; H, 4.31; N,
24
18
2
2
6.65. Found: C, 68.22; H, 4.47; N, 6.45.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(4ꢀChlorophenyl)(1ꢀ(3,4ꢀdifluorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀ
yl)methanone (40)
The title compound was synthesized from 13 (1.4 mmol) and 4ꢀchlorobenzoylchloride (1.54
1
mmol), yield 15%, white crystals, mp 215ꢀ216 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.00 (s,
1H), 7.55 – 7.50 (m, 2H), 7.49 – 7.40 (m, 4H), 7.34 (d, J = 8.1 Hz, 2H), 7.15 (s, 1H), 7.10
(dd, J = 8.1, 1.1 Hz, 1H), 7.02 (td, J = 7.5, 1.0 Hz, 1H), 6.86 (s, 1H), 3.65 (s, 1H), One signal
is missing (CH
2
) under the water peak, 2.88 (t, J = 10.6 Hz, 1H), 2.77 (d, J = 12.5 Hz, 1H).
) δ 8.02 (s, 1H), 7.53 (d, J = 7.8 Hz, 1H), 7.43 – 7.36 (m, 2H),
1
H NMR (600 MHz, CDCl
3
7.36 – 7.28 (m, 3H), one signal is missing under the chloroform peak,7.23 – 7.20 (m, 1H),
7.17 – 7.11 (m, 2H), 7.08 (dt, J = 9.9, 8.1 Hz, 1H), 7.02 (s, 1H), 3.76 (d, J = 11.8 Hz, 1H),
13
3
.39 – 3.29 (m, 1H), 2.93 (t, J = 11.0 Hz, 1H), 2.82 (dd, J = 15.6, 4.2 Hz, 1H). C NMR (126
MHz, DMSOꢀd
6
) δ 169.02, 148.51 (dd, J = 245.3, 12.7 Hz), 148.22 (dd, J = 246.1, 12.7 Hz,
137.98, 136.51, 134.86, 134.57, 130.75, 128.85 (2C), 128.70 (2C), 126.25, 125.09, 121.76,
1
4
3
18.97, 118.23,117.72 (d, J = 17.0 Hz), 117.22 (d, J = 17.0 Hz). , 111.53, 108.56, 51.22,
1.63, 21.67. Anal. Calcd for C H ClF N O: C, 68.17; H, 4.05; N, 6.62. Found: C, 67.99; H,
24
17
2
2
.99; N, 6.43.
(1ꢀ(4ꢀBromophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀyl)(4ꢀchlorophenyl)methanone
41)
(
The title compound was synthesized from 15 (0.83 mmol) and 4ꢀchlorobenzoylchloride (0.92
1
mmol), yield 41%, white needles, mp 236ꢀ237 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 11.01 (s,
1H), 7.57 (t, J = 8.4 Hz, 2H), 7.54 – 7.50 (m, 2H), 7.46 (dd, J = 13.2, 8.1 Hz, 3H), 7.32 (d, J =
28
ACS Paragon Plus Environment

Page 29 of 64
Journal of Medicinal Chemistry
1
2
3
4
5
6
7
8
9
8.0 Hz, 1H), 7.27 (d, J = 6.8 Hz, 2H), 7.12 – 7.08 (m, 1H), 7.05 – 6.98 (m, 1H), 6.88 (s, 1H),
3
2
1
.64 (d, J = 10.5 Hz, 1H), One signal is missing (CH ) under the water peak , 2.87 (s, 1H),
2
1
.75 (d, J = 14.2 Hz, 1H). H NMR (600 MHz, CDCl
3
) δ 8.09 (s, 1H), 7.52 (d, J = 7.8 Hz,
H), 7.43 – 7.37 (m, 4H), 7.32 – 7.24 (m, 5H), one signal is missing under the chloroform
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
peak, 7.23 – 7.16 (m, 1H), 7.17 – 7.11 (m, 1H), 7.02 (s, 1H), 3.79 – 3.71 (m, 1H), 3.38 – 3.28
13
(m, 1H), 2.91 (t, J = 11.3 Hz, 1H), 2.80 (dd, J = 15.5, 4.1 Hz, 1H). C NMR (126 MHz,
DMSOꢀd ) δ 168.86, 139.67, 136.47, 134.96, 134.49, 131.63 (2C), 130.99, 130.45 (2C),
6
1
28.86 (2C), 128.62 (2C), 126.29, 121.65, 121.31, 118.92, 118.15, 111.48, 108.39, 51.38,
1.49, 21.74. Anal. Calcd for C24 O: C, 61.89; H, 3.90; N, 6.01. Found: C, 61.52; H,
4
H18BrClN
2
4.07; N, 5.77.
(4ꢀChlorophenyl)(1ꢀ(3,4ꢀdichlorophenyl)ꢀ3,4ꢀdihydroꢀ1Hꢀpyrido[3,4ꢀb]indolꢀ2(9H)ꢀ
yl)methanone (42)
The title compound was synthesized from 19 (0.73 mmol) and 4ꢀchlorobenzoylchloride (0.81
1
mmol), yield 42%, white crystals, mp 240ꢀ241 °C. H NMR (500 MHz, DMSOꢀd
6
) δ 10.99 (s,
1H), 7.65 (d, J = 8.4 Hz, 1H), 7.57 – 7.42 (m, 6H), 7.32 (dd, J = 20.9, 7.9 Hz, 2H), 7.14 –
7.08 (m, 1H), 7.02 (td, J = 7.5, 0.9 Hz, 1H), 6.86 (s, 1H), 3.66 (s, 1H), One signal is missing
1
(
CH
2
) under the water peak, 2.87 (dd, J = 18.7, 7.9 Hz, 1H), 2.78 (d, J = 12.5 Hz, 1H). H
NMR (600 MHz, CDCl
3
) δ 8.16 (s, 1H), 7.53 (d, J = 7.8 Hz, 1H), 7.44 (s, 1H), 7.41 – 7.38
(m, 2H), 7.35 (d, J = 8.3 Hz, 1H), 7.34 – 7.25 (m, 4H), 7.25 – 7.19 (m, 1H), 7.18 – 7.12 (m,
1
1
1
H), 7.01 (s, 1H), 3.76 (dd, J = 12.5, 4.6 Hz, 1H), 3.36 – 3.29 (m, 1H), 2.91 (d, J = 11.8 Hz,
13
H), 2.82 (dd, J = 15.7, 4.1 Hz, 1H). C NMR (126 MHz, DMSOꢀd ) δ 169.08, 141.25,
6
36.51, 134.78, 134.61, 131.34, 131.25, 131.01, 130.83, 130.46, 130.14, 128.85 (2C), 128.71
(2C), 126.23, 121.81, 119.01, 118.26, 111.56, 108.69, 51.21, 41.78, 21.63. Anal. Calcd for
C
24
H17Cl
3
N
2
O: C, 63.25; H, 3.76; N, 6.15. Found: C, 62.89; H, 4.06; N, 6.09.
29
ACS Paragon Plus Environment