Synthesis and cytotoxic activity of 5,6-heteroaromatically annulated pyridine-2,4-diamines

Article abstract of DOI:10.1016/j.bmc.2009.05.016

A series of 5,6-heteroaromatically annulated pyridine-2,4-diamines have been synthesized and their in vitro cytotoxic activities evaluated against six human cancer cell lines. Benzo[g] annulated pyrido[2,3-b]indolediamines 7a-b and 8 showed relatively hig

Full text of DOI:10.1016/j.bmc.2009.05.016

Bioorganic & Medicinal Chemistry 17 (2009) 4406–4419
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis and cytotoxic activity of 5,6-heteroaromatically annulated
pyridine-2,4-diamines
C. Willemann a, R. Grünert b, P. J. Bednarski b, R. Troschütz a,
*
a Department Chemie und Pharmazie, Universität Erlangen-Nürnberg, Lehrstuhl für Pharmazeutische Chemie, Schuhstr. 19, D-91052 Erlangen, Germany
b Institut für Pharmazie, Universität Greifswald, Friedrich-Ludwig-Jahn-Str. 17, D-17487 Greifswald, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 5,6-heteroaromatically annulated pyridine-2,4-diamines have been synthesized and their
in vitro cytotoxic activities evaluated against six human cancer cell lines. Benzo[g] annulated pyr-
ido[2,3-b]indolediamines 7a–b and 8 showed relatively high cytotoxic activity as well as most of the dia-
mines with pyrrolo[2,3-b]pyridine 17, thieno[2,3-b]pyridine and furo[2,3-b]pyridine 26–28, 1,8-
naphthyridine 32 and 34 and benzo[h]quinoline 37 skeletons. Surprisingly, pyrido[2,3-b]indolediamines
13 and 14 without benzo[g] annulation were inactive. None of the new compounds were as potent as
ellipticine, the reference compound.
Received 22 April 2009
Accepted 7 May 2009
Available online 12 May 2009
Dedicated to Professor Dr. H. J. Roth,
Karlsruhe, on the occasion of his 80th
birthday
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Pyridinediamines
Carbolines
Heterocyclic compounds
Cytotoxicity
1. Introduction
furo-annulated pyridines of type C and 1,8-naphthyridines of type
D, as illustrated in Scheme 1.1
Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) (1), first
isolated in 1959 from the leaves of Ochrosia elliptica (Apocyna-
ceae),1,2 and its related alkaloids 9-hydroxyellipticine and olivacine
show potent antitumour activity.3 As a result, a large number of
ellipticine analogues have been prepared by research groups
worldwide to enhance antitumour activity. In particular, changes
to the heterocyclic ring system have been undertaken by a number
of groups.4 For example, Bisagni5 as well as Dotzauer6,7 investi-
gated new carboline analogues of ellipticine lacking the central
ring C. Dotzauer synthesized 2,4-diamino-9H-benzo[g]pyrimi-
do[4,5-b]indol-6-oles of type 2a and 2b that showed good cyto-
toxic activity.6 In continuation of our work we have focused on
the synthesis of 3-deaza analogues of 2a and 2b; for example
benzo[g]pyrido[2,3-b]indole derivatives A and pyrido[2,3-b] indole
derivatives B. In order to modify the structure of A and B, we fur-
ther planned to prepare and test the cytotoxic effects of pyridine-
2,4-diamines with annulated heteroaromatic systems; for example
pyrrole, furane, thiophene and pyridine each substituted with
methyl and/or phenyl groups. This strategy leads to planar
benzo[g]pyrido[2,3-b]indoles of type A, and pyrido[2,3-b]indoles
of type B; as well as to tetrahydroindolo-, pyrrolo-, thieno- and
2. Results and discussion
2.1. Chemistry
2.1.1. Type A compounds: N9,N9-dimethyl-11H-benzo[g]pyrido
[2,3-b]indole-7,9-diamines 7 and 8
The preparation of the type A compounds began with the synthe-
sis of 2-amino-1H-benzo[g]indole-3-carbonitrile (4) according to
literature procedure from 2-bromo-1-nitronaphthalene 3 and mal-
ononitrile.8 We obtained our title compounds by applying the meth-
od of Campbell et al.9,10 on o-aminonitrile 4. After condensation of 4
with 1,1-dimethoxy-N,N-dimethylethanamine (DMA-DMA) to gain
the acetamidine derivative 5, the N-1 of benzo[g]indole 5 was pro-
tected with a methyl or 4-methoxybenzyl group by treatment with
appropriate alkyl halogenides11–16 to enable ring closure under vig-
orous conditions. For example, ring closure was achieved by reflux-
ing in toluene with freshly powdered sodium amide as a strong base
or lithium diisopropyl amide (LDA) in THF at ꢀ70 °C, followed by
quenching with water to yield the N-1 protected benzo[g]pyridoin-
dole derivatives 7. Deprotection to N9,N9-dimethyl-11H-
benzo[g]pyrido[2,3-b]indole-7,9-diamine (8) was achieved by
reacting 4-methoxybenzyl derivative 7b with trifluoracetic acid
and concd sulfuric acid in anisole at room temperature (Scheme 2).
* Corresponding author. Tel.: +49 9131 85 23923; fax: +49 9131 85 22587.
E-mail address: reinhard.troschuetz@medchem.uni-erlangen.de (R. Troschütz).
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.05.016

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4407
HO
NH2
NH2
N
N
N
N
NR2
N
NR22
H
9
R1
Me
Me
type A
1
4
2a
N
N
H
6
HO
NH2
NH2
Ellipticine (1)
N
NR22
N
N
H
N
N
NR2
R1
type B
2b
R3
NH2
NH2
NH2
N
R3
R4
R4
NR22
N
NR22
N
NR22
X
N
N
R1
type D
type C
X = O
R3
X = S
X = N
R3
N
R3
NH2
N
NH2
NH2
N
R4
R4
R4
NR22
O
S
N
NR22
NR22
R1
Scheme 1. R3, R4 = methyl, phenyl.
2.1.2. Type B compounds: N2,N2-dimethyl-9H-pyrido[2,3-
b]indole-2,4-diamines 13 and 14
Type B compounds were prepared following the same proce-
dure as mentioned above for benzo[g] annulated derivatives 7
and 8 by starting with 2-bromo-1-nitrobenzene (9) and malononit-
rile.8 After condensation with DMA-DMA and N-1 protection with
the a methyl as well as a 4-methoxybenzyl group,11–16 ring closure
was performed under strong basic conditions9,10 (Scheme 3).
Br
CN
CN
CN
CH3
CH3
a
c
b
NMe2
NMe2
NO2
NH2
N
N
N
N
H
N
R1
6
H
3
5
4
6/7 R1
a
b
Me
4-OMeBn
d
H2N
H2N
e
NMe2
NMe2
N
N
N
N
H
R1
8
7
Scheme 2. Reagents and conditions: (a) (1) malononitrile, NMP, aq NaOH, rt 50 h; (2) DMF, NaHCO3, Na2S2O4, rt, o.n;. (b) DMA-DMA, methanol, reflux 3 h (5: rt. 5 h); (c) 6a:
(1) MeI, KOH, acetone, 0 °C 30 min; (2) rt 18 h; 6b: 4-methoxybenzylbromide, KOH, acetone, rt 2 h; (d) 7a: NaNH2, toluene, reflux 5 h; 7b: NaNH2, toluene, reflux 5 h; or (1)
LDA, THF/n-hexane, ꢀ70 °C 30 min; (2) rt, o.n.; (e) (1) starting from 7b TFA, concd H2SO4, anisole, rt 90 min; (2) ice water; (3) NaHCO3, rt, o.n.

4408
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
Cleavage of the 4-methoxybenzyl group succeeded with
DMA-DMA or phosphorous oxychloride and N,N-dimethylacet-
amide. Ring closure leading to pyrrolopyridinediamines 17a–d
was performed by using sodium hydride or sodium amide in
refluxing dioxane or toluene.9,10 (Schemes 4 and 5).
trifluoroacetic acid/concd sulfuric acid in anisole. In the case of
pyridoindole 14, we also wanted to explore the reactivity of dieth-
oxymethyl protected derivative 12c.17 During the ring closing
reaction, which afforded 9-(diethoxymethyl)-N2,N2-dimethyl-9H-
pyrido[2,3-b]indole-2,4-diamine (13c), the protecting diethoxym-
ethyl group was partially cleaved to give the desired pyrido
[2,3-b]indole 14 as a side product.
Theo-aminonitriles 18and 19 are knownfrom theliterature.19–21
They could easily be converted into their amidines 20 and 21 by our
standard method B by using DMA-DMA or phosphorous oxychloride
and N,N-dimethylacetamide.9,10 Thereafter, ring closure with
sodium amide in refluxing toluene afforded the annulated pyridin-
ediamines 26a–e and 27b,e. The reaction pathway in Scheme 6
shows the condensation of 18/19 with orthoester 1,1,1-triethoxye-
thane to form the imidates 22/23. Methyl imidate 23b was obtained
as a side product of the condensation with DMA-DMA. Thereafter,
aminolysis was carried out in pyrrolidine to afford derivatives 24/
2.1.3. Type C compounds: 5,6-disubstituted 1H-pyrrolo[2,3-
b]pyridine-4,6-diamines 17, thieno[2,3-b]pyridine-4,6-diamines
26 and furo[2,3-b]pyridine-4,6-diamines 27
The acetamidine derivatives 16a–d were synthesized by heat-
ing N-1 substituted 2-aminopyrrole-3-carbonitriles18 15a–d with
CN
CN
CN
Br
CH3
CH3
c
a
b
NMe2
NMe2
N
NH2
N
NO2
N
N
H
N
H
R1
9
d
10
11
12
H2N
H2N
R1
e
12/13
NMe2
NMe2
a
b
c
Me
N
N
N
N
4-OMeBn
CH(OEt)2
H
R1
14
13
Scheme 3. Reagents and conditions: (a) (1) malononitrile, NMP, aq NaOH, rt 50 h; (2) DMF, NaHCO3, Na2S2O4, rt, o.n; (b) DMA-DMA, methanol, reflux 3 h (5: rt 5 h); (c) 12a:
(1) MeI, KOH, acetone, 0 °C 30 min; (2) rt 18 h; 12b: 4-methoxybenzylbromide, KOH, acetone, rt 2 h; 12c: triethyl orthoformate, 160 °C, 48 h; (d) NaNH2, toluene, reflux 5 h;
(e) starting from 13b: (1) TFA, concd H2SO4, anisole, rt 90 min; (2) ice water; (3) NaHCO3, rt, o.n.; starting from 13c: anisole, trifluoroacetic acid, concd sulfuric acid; 90 min, rt.
R1 R3 R4
15a Bn -(CH2)4-
15b Bn
Me Me
15c allyl Ph Ph
15d Bn Ph Ph
16a Bn -(CH2)4-
H
2N
R3
R3
R3
CN
CN
CH3
b
a
NMe2
16b Bn
16c allyl
16d Bn
17a Bn
Me Me
NMe2
R4
N
N
R4
NH2
R4
N
N
Ph Ph
Ph Ph
-(CH2)4-
N
R1
R1
R1
17b Bn
17c allyl
17d Bn
Me Me
Ph Ph
Ph Ph
17
15
16
Scheme 4. Reagents and conditions: (a) DMA-DMA, methanol, reflux; or DMA-DMA, reflux; or POCl3, N,N-dimethylacetamide, chloroform, reflux; (b) NaNH2, toluene, reflux;
or NaH, dioxane, reflux.
X=S
18/20/26 R3 R4
a
-(CH2)4-
H2N
R3
CN
R3
R3
CN
c
Me Ph
Ph Ph
CH3
b
a
e
NMe2
NMe2
R4
NH2
N
R4
N
X
R4
X
X
X=O
19/21/27 R3 R4
20/21
26/27
18/19
b
e
Me Me
Ph Ph
Scheme 5. Reagents and conditions: (a) DMA-DMA, methanol, reflux; or DMA-DMA, reflux; or POCl3, N,N-dimethylacetamide, chloroform, reflux; (b) NaNH2, toluene, reflux.

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4409
H2N
R3
R3
R3
CN
R3
CN
CN
CH3
CH3
a
b
c
R2
N
N
R4
R4
R4
R4
N
NH2
N
N
X
X
X
X
24/25
28/29
18/19
22/23
X
R2
R3
R4
22e
23b
23e
24e
25b
25e
28e
29b
29e
S
OEt
OMe
OEt
Ph
Ph
O
O
S
Me Me
Ph
Ph
Ph
pyrrolidin-1-yl Ph
O
O
S
O
O
pyrrolidin-1-yl Me Me
pyrrolidin-1-yl Ph
pyrrolidin-1-yl Ph
Ph
Ph
pyrrolidin-1-yl Me Me
pyrrolidin-1-yl Ph
Ph
Scheme 6. Reagents and conditions: (a) 22e, 23e: 1,1,1-triethoxyethane, reflux; 23b: DMA-DMA, reflux; (b) pyrrolidine, reflux; (c) NaNH2, toluene, reflux.
26. After ring closure with our standard method, we obtained annu-
lated pyridine-2,4-diamines with alternative amino substitution
(28e, 29b,e).
crystal violet, was used.27 In these studies, six human cancer cell
lines from solid tumours were used: two human bladder cancer
cell lines 5637 (ACC 35) and RT-4 (ACC 412), two human lung
cancer cell lines A-427 (ACC234) and LCLC-103H (ACC 384),
the human pancreas cancer cell line DAN-G and the human
mamma cancer cell line MCF-7. The assay measures the
inhibition of cell growth caused by a 96 h continuous exposure
to test compound. Substances that inhibited cell growth at
2.1.4. Type D compounds: 1,8-naphthyridine-2,4-diamines 32
and 34
The 1,8-naphthyridine-2,4-diamines 32c,d,e could also be pre-
pared by using our standard method described above9,10,22,23
(Scheme 7 and 8).
20 lM by 50% or more compared to untreated controls in at
Encouraged by our results, we planned to synthesize one
benzo[h]quinoline derivative representing an analogue of N9,N9-di-
methyl-11H-benzo[g]pyrido[2,3-b]indole-7,9-diamine (8) without
the pyrrole ring. Starting from 1-amino-2-naphthonitrile (35),24–26
general synthetic procedures as described above led us to the carbo-
cyclic annulated N2,N2-dimethylbenzo[h]quinoline-2,4-diamine
(37), which also showed good cytotoxic activity (Scheme 9).
least one cell line were considered active. Active compounds
were tested in all six cell lines at five concentrations to deter-
mine the IC50 values. Resulting IC50 values of the cytotoxic study
are reported in Table 1.
Type A compounds in general show activity (7a and 8). It is sug-
gestive that the smaller the N-substitution in position 11, the bet-
ter the cytotoxic potency (compare 7a, 7b, 8). The best substance of
this series was compound 8 with a free NH position. Compared to
annulated carbolines 13a–c and 14 of type B, which showed no
activity at all, we assume benzo[g] annulation is necessary for
the activity of this product class.
2.2. In vitro cytotoxic activity
To evaluate the in vitro cytotoxic activity of the annulated
2,4-diaminopyridine derivatives 7a,b, 8, 13a–c, 14, 17a–d,
26a,c,e, 27b,e, 28e, 29b,e, 32c–e, 34e and 37 on human cancer
cells, an established microtiter assay, based on cell staining with
For type C substances, one or two phenyl or benzyl substituents
were necessary for good activity, whereas dimethyl substitution on
pyrrole, thiophene or furane or even a tetrahydroindole annulation
NH2
30/31/32
R3 R4
Me Ph
Ph Me
Ph Ph
R3
R4
R3
R3
R4
CN
CN
N
b
c
d
e
a
CH3
NMe2
R4
N(Me)2
N
N
N
N
NH2
31
30
32
Scheme 7. Reagents and conditions: (a) DMA-DMA, methanol, reflux; or DMA-DMA, reflux; (b) NaNH2, toluene, reflux.
NH2
CN
CN
N
a
b
CH3
N
N
N
N
NH2
N
N
33e
34e
30e
Scheme 8. Reagents and conditions: (a) 1-acetylpyrrolidine, POCl3, rt; (b) NaNH2, toluene, reflux.

4410
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
H2N
NMe2
N
N
H
8
NH2
CN
CN
CH3
a
b
N
NMe2
NH2
NMe2
N
35
36
37
Scheme 9. Reagents and conditions: (a) DMA-DMA, methanol, reflux; (b) NaNH2, toluene, reflux.
on the pyridinediamine were not advantageous. Focusing on com-
pounds 26e and 27e, the thienopyridinediamine was slightly more
active than its furane analogue.
thyridin-4-amine (34e), yielded the substance with the greatest
activity of all the compounds tested. None of the new compounds
were as active as the reference compound ellipticine, however.
The greatest potency, however, was found in the naphthyridine
derivatives of type D. Strong cell growth inhibition was observed
with the diphenyl compound 32e, and the replacement of the 6-
phenyl group for a methyl, that is, 32c, resulted in little change
in potency. Surprisingly, the regioisomer 32d, wherein only the
positions of the phenyl and the methyl substituents had been
exchanged, was void of cytotoxic activity. Biochemical studies will
be required to identify the reason for the interesting difference in
cytotoxicity of these regioisomers.
3. Conclusion
In summary, we have developed an efficient route to a very heter-
ogeneous series of 5,6-heteroaromatically annulated pyridine-2,4-
diamines and evaluated them for in vitro cytotoxic activities against
six human cancer cell lines. Surprisingly, antiproliferative activity
was observed when the inactive carbolinediamines were benzo[g]
annulated, leading to compounds 7a and 8. Furthermore, the skeletal
structure was modified and various substituted pyrrolo-, thieno- and
furopyridinediamines as well as naphthyridinediamines were
Exchange of the dimethylamino group in 32e for a pyrrolidine
substitution, resulting in 6,7-diphenyl-2-pyrrolidin-1-yl-1,8-naph-
Table 1
Cell growth inhibitory activity (IC50
,
l
M) of compounds 7a,b, 8, 13a–c, 14, 17a–d, 26a,c,e, 27b,e, 28e, 29b,e, 32c–e, 34e and 37 against six human cancer cell lines
IC50 M) SD
Compound
(l
5637
RT-4
A-427
LCLC-103H
DAN-G
MCF-7
7a
7b
>20
>20
12.9 0.66
>20
14.3 2.81
>20
>20
>20
>20
>20
21.3 4.33
>20
8
7.90 1.31
>20
>20
>20
>20
6.56 1.85
>20
n.d.
>20
>20
6.58 1.07
>20
>20
>20
>20
9.67 1.92
>20
>20
>20
>20
9.84 0.34
>20
>20
>20
>20
7.52 0.88
>20
>20
>20
>20
13a
13b
13c
14
17a
17b
17c
17d
26a
26c
26e
27b
27e
28e
29b
29e
32c
32d
32e
34e
37
n.d.
n.d.
n.d.
>20
>20
>20
>20
>20
>20
10.6 3.61
>20
>20
9.79 2.53
>20
>20
>20
>20
13.7 1.09
12.5 0.98
8.93 1.28
0.80 0.04
>20
>20
>20
>20
n.d.
11.8 2.23
16.9 2.78
>20
19.6 2.37
12.1 0.65
>20
>20
6.19 0.84
>20
>20
>20
>20
>20
17.7 4.20
5.00 1.62
>20
14.4 2.24
12.0 1.99
7.82 2.45
1.21 0.16
12.5 3.24
3.93 0.65
n.d.
13.1 0.66
9.04 1.71
>20
>20
>20
>20
>20
17.7 2.08
10.1 2.41
>20
14.9 4.31
8.18 0.49
>20
18.4 3.40
8.82 2.12
>20
8.03 1.05
2.75 0.44
10.0 2.41
0.89 0.20
15.3 2.41
11.2 2.33
>20
14.6 1.60
8.76 1.53
>20
13.8 1.19
11.8 2.85
n.d.
7.93 0.85
4.33 0.67
8.22 0.97
0.89 0.06
16.4 1.56
15.2 2.29
>20
>20
8.17 2.38
>20
>20
18.1 2.71
>20
11.6 1.92
6.34 1.17
10.2 1.22
n.d.
13.6 2.21
16.2 3.84
>20
18.8 2.76
13.7 3.96
>20
14.7 1.57
11.7 2.47
>20
7.79 1.03
4.08 0.70
6.20 1.06
0.43 0.22
Ellipticine
Values with standard deviations (SD) are averages of at least five independent determinations. Values >20
compound caused >50% growth inhibition but IC50 value was not determined.
lM indicate less than 50% growth inhibition at 20 lM. n.d.:

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4411
synthesized and evaluated in our cell systems. Some of the com-
pounds, most notably 34e, showed relatively good cell growth inhibi-
tion. Nevertheless, their activity was less than that of ellipticine.
Whether the mechanism of cytotoxic action of our new compounds
resembles those of ellipticine, which has been reported to be a
DNA-intercalator,28 a topoisomerase II inhibitor29 as well as undergo-
ing metabolic activation to reactive electrophiles by CYP45030 and
peroxidases31 that can covalently bind to DNA, has yet to be
investigated.
removed in vacuo and the product purified in a first step by flash
chromatography on silica gel by using a gradient from 100% cyclo-
hexane to cyclohexane/ethyl acetate/methanol = 5:4:1 as eluent
followed by a gravity column chromatography on silica gel of the
fractions between Rf = 0.3 and Rf = 0.7 with a gradient from 100%
chloroform to chloroform/methanol = 96:4 as eluent to yield
0.44 g (12%) as a brown powder. Mp 243–24 °C; IR NaCl:
m
d
(cmꢀ1) = 3405, 3293, 2190, 1604; 1H NMR: (DMSO-d6);
(ppm) = 6.54 (s, 2H, NH2, exchangeable with D2O), 7.30 (m, 1H,
H-8), 7.41 (d, 1H, J1 = 1.1 Hz, J2 = 8.6 Hz, H-4), 7.47 (m, 1H, H-7),
7.52 (d, 1H, J = 8.6 Hz, H-5), 7.86 (m, 1H, H-6), 8.15 (m, 1H, H-9),
11.70 (s, 1H, NH, exchangeable with D2O); 13C NMR (DMSO-d6);
d (ppm) = 64.2 (C-3), 116.4 (C-4), 117.5 (CN), 120.0 (C-5), 120.5
(C-9a), 121.0 (C-9), 122.6 (C-7), 123.8 (C-3a), 125.0 (C-9b), 125.5
(C-5), 128.5 (C-6), 128.6 (C-5a), 152.5 (C-2); MS m/z (rel int.
%) = 207 (100) [M+]; HRMS (C13H9N3) calcd: 207.0796. Found:
207.0796. Anal. Calcd for (C13H9N3: C, 75.40; H, 4.38; N, 20.29.
Found: C, 75.31; H, 4.24; N, 20.13.
4. Experimental
4.1. General
Starting materials were obtained from commercial sources and
were used without further purification. Reaction progress was fol-
lowed by thin-layer chromatography (TLC) with commercial silica
gel plates (Merck, silica gel F254 on aluminum sheets). Column
chromatography was done on Silica Gel 60 (Merck). Melting points
were determined in open capillary tubes on a Buechi 510 melting
point apparatus and are uncorrected. Elemental analyses were per-
formed by the Institut für Organische Chemie (Universität Erlan-
gen/Nürnberg) with a Carlo Erba Elemental Analyzer 1108. 1H
nuclear magnetic resonance (1H NMR) spectra were determined
with a Bruker AM 360 (360 MHz) spectrometer in appropriate deu-
terated solvents and are expressed in parts per million (d, ppm)
downfield from tetramethylsilane (internal standard). NMR data
are given as multiplicity (s, singlet; d, doublet; dd, double doublet;
m, multiplet), coupling constants (J), and numbers of protons. All
NH, OH and NH2 signals were exchangeable with D2O. Mass spec-
tra (MS, HRMS) were taken with a Finnigan MAT TSQ 70 mass spec-
trometer in the electron impact mode (70 eV). Infrared (IR) spectra
were obtained on a Jasco FT/IR 410 spectrometer.
4.1.2.2. N0-(3-Cyano-1H-benzo[g]indol-2-yl)-N,N-dimethyleth-
animidamide (5). According to the general procedure B, this com-
pound was obtained from 2-amino-1H-benzo[g]indole-3-
carbonitrile (4) (1.0 mmol, 207.2 mg) after 5 h at rt. The solvents
were removedin vacuo and the productpurified by flashchromatog-
raphy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate = 5:5 as eluent to yield 0.17 g (61%) as
beige crystals. Mp 210–211 °C; IR NaCl:
m
(cmꢀ1) = 3259, 2927,
2198, 1585; 1H NMR: (DMSO-d6); d (ppm) = 2.17 (s, 3H, H-2), 3.15
(s, 6H, N(CH3)2), 7.35–7.62 (m, 4H, H-60, H-70, H-80, H-90), 7.93 (m,
1H, H-50), 8.30 (m, 1H, H-40), 12.13 (s, 1H, NH, exchangeable with
D2O); 13C NMR (DMSO-d6); d (ppm) = 16.1 (C-2), 37.3 and 38.3
(N(CH3)2), 73.2 (C-30), 117.0 (C-40), 117.7 (CN), 120.4 (C-90), 120.9
(C-9a0), 121.1 (C-50), 123.3 (C-3a0), 123.4 (C-70), 125.7 (C-60), 126.6
(C-5a0), 128.5 (C-80), 129.2 (C-9b0), 154.2 (C-20), 161.1 (C-1); MS m/
z (rel int. %) = 276 (100) [M+]. Anal. Calcd for C17H16N4: C, 73.89; H,
5.84; N, 20.27. Found: C, 74.04; H, 5.69; N, 20.03.
4.1.1. General procedure A for preparation of annulated
pyridinediamine derivatives 7a,b; 13a,b,c; 14; 17c,c; 26a,c,e;
27b,e; 28e; 29b,e; 32c,d,e; 34e; 37
4.1.2.3. N0-(3-Cyano-1-methyl-1H-benzo[g]indol-2-yl)-N,N-dime-
thylethanimidamide (6a). To a solution of N0-(3-cyano-1H-benzo-
[g]indol-2-yl)-N,N-dimethylethanimidamide (5) (0.24 mmol, 65 mg)
in acetone (5 mL), freshly powdered KOH (1.2 mmol, 67 mg) was
added at 0 °C and the suspension stirred at that temperature for
30 min. Then, methyliodide (0.5 mmol, 71 mg) was added and the
mixture allowed to reach rt and then stirred for additional 18 h.
After evaporation to dryness, the residue was mixed with water
(10 mL), the pH >9 adjusted if necessary and extracted with ethyl
acetate. The organic phase was dried with Na2SO4 and the solvent
removed in vacuo. The product was purified by flash chromatogra-
phy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate/methanol = 5:4:1 as eluent to yield
The reactions were carried out under a nitrogen atmosphere.
Freshly powdered sodium amide (2.5 equiv) was suspended in
dry toluene (10 mL). A solution of the appropriate acetamidine
derivative (1.0 equiv) in dry toluene (10 mL) was added carefully
at 50 °C. Thereafter, the mixture was refluxed the time indicated.
After cooling down to rt, the surplus of sodium amide was
quenched with a saturated aqueous solution of NaCl and subse-
quently water. The aqueous phase was extracted with ethyl ace-
tate. The organic phases were dried with Na2SO4. The solvents
were removed in vacuo and, if necessary, the product purified by
flash chromatography on silica gel.
4.1.2. General procedure B for preparation of acetamidine and
imidate derivatives 5; 20a,c,e; 21b,e; 23b; 31c,d,e; 36
38 mg (56%) as beige crystals. Mp 128–130 °C; IR NaCl:
m
(cmꢀ1) = 2965, 2927, 2202, 1589; 1H NMR: (DMSO-d6); d (ppm) =
2.11 (s, 3H, H-2), 3.19 (s, 6H, N(CH3)2), 4.04 (s, 3H, arN-(CH3),
7.41–7.70 (m, 4H, ar), 8.00 (m, 1H, ar), 8.55 (m, 1H, ar); MS m/z
(rel int. %) = 290 (100) [M+], 275 (14), 234 (36), 219 (20), 164 (32);
HRMS (C18H18N4) calcd: 290.1531. Found: 290.1531. Anal. Calcd
for C18H18N4: C, 74.51; H, 6.25; N, 19.31. Found: C, 74.71; H, 6.29;
N, 19.22.
To a solution of the appropriate o-aminonitrile (3.0 mmol) in
methanol (10 mL), 1,1-dimethoxy-N,N-dimethylethanamine (DMA-
DMA, 1.0 mL) was added and refluxed for 3 h if not indicated other-
wise. The volatile substances were distilled off and the product was
purified by flash chromatography, if necessary.
4.1.2.1. 2-Amino-1H-benzo[g]indole-3-carbonitrile (4). Ten
molar aqueous NaOH (5.1 mL) was added dropwise to a stirred
solution of 2-bromonitronaphthalene (3) (17.0 mmol, 4.29 g) and
malononitrile (17.0 mmol, 1.12 g) in 1-methylpyrrolidin-2-one
(NMP, 17 mL). Thereafter, the mixture is stirred for 50 h at rt. After
diluting with DMF (30 mL), a solution of NaHCO3 (11.9 g in 50 mL
of water) was added. Then, Na2S2O4 (8.5 g) and additionnal NaH-
CO3 (11.9 g) were added and stirred overnight. The solvents were
4.1.2.4. N0-[3-Cyano-1-(4-methoxybenzyl)-1H-benzo[g]indol-2-
yl]-N,N-dimethylethanimidamide (6b). To a solution of N0-(3-
cyano-1H-benzo[g]indol-2-yl)-N,N-dimethylethanimidamide (5)
(0.50 mmol, 138.2 mg) in acetone (5 mL) freshly powdered KOH
(2.5 mmol, 0.14 g) was added at 0 °C and the suspension stirred
at that temperature for 30 min. Then, 4-methoxybenzylbromide
(1.0 mmol, 0.20 g) was added dropwise and the mixture allowed

4412
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
to reach rt and then stirred for additional 2 h. The insoluble KBr was
filtered off and the filtrate evaporated to dryness. The product was
purified by flash chromatography on silica gel by using a gradient
from 100% cyclohexane to cyclohexane/ethyl acetate/metha-
nol = 5:4:1 as eluent to yield 0.20 g (98%) as a beige powder. Mp
396.1950. Found: 396.1950. Anal. Calcd for C25H24N4O: C, 75.79; H,
6.11; N, 14.14. Found: C, 75.92; H, 6.28; N, 13.95.
4.1.2.7. N9,N9-Dimethyl-11H-benzo[g]pyrido[2,3-b]indole-7,9-
diamine (8). To a solution of 11-(4-methoxybenzyl)-N9,N9-di-
methyl-11H-benzo[g]pyrido[2,3-b]indole-7,9-diamine (7b) (0.05
mmol, 19.8 mg) in anisole (0.5 mL) trifluoroacetic acid (3 mL) and
concd sulfuric acid (0.2 mL) were carefully added. The mixture was
stirred at rt for 90 min. Thereafter, the mixture was pipetted into a
saturated aqueous solution of NaHCO3 (20 mL) with cooling and al-
lowed to stand overnight. The next day, the solution was extracted
with ethyl acetate, the organic phase was dried with Na2SO4 and
evaporatedto dryness. Theproductwaspurifiedbyflashchromatog-
raphy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate/methanol = 50:45:5 as eluent to yield
85–87 °C; IR NaCl:
m
(cmꢀ1) = 3008, 2952, 2931, 2834, 2202, 1585;
1H NMR: (DMSO-d6); d (ppm) = 2.15 (s, 3H, H-2), 3.08 and 3.11
(s, 3H, respectively, N(CH3)2), 3.66 (ar-NCH3), 5.71 (s, 2H, benzyl
–CH2–), 6.84 (m, 2H, H-200, H-600), 6.99 (H-300, H-500), 7.29–7.38 (m,
2H, H-70, H-80), 7.60–7.68 (m, 2H, H-60, H-90), 7.93 (m, 1H, H-50),
8.14 (m, 1H, H-40); 13C NMR (DMSO-d6); d (ppm) = 15.9 (C-2), 37.3
(N(CH3)2), 54.9 (–CH2–), 55.7 (OCH3), 72.6 (C-30), 113.4 (CN), 114.1
(C-300, C-500), 117.0 (C-40), 117.4 (C-3a0), 120.5–130.3 (11C, Ar),
154.0 (C-400), 158.2 (C-1), 161.3 (C-20); MS m/z (rel int. %) = 396
(42) [M+], 275 (100), 121 (25). Anal. Calcd for C25H24N4O: C, 75.73;
H, 6.10; N, 14.13. Found: C, 75.65; H, 5.95; N, 14.33.
13 mg (94%) as a beige powder. Mp 121–115 °C; IR NaCl:
m
(cmꢀ1) = 3498, 3386, 3101, 3008, 2927, 1604, 1577; 1H NMR:
(DMSO-d6); d (ppm) = 3.09 (s, 6H, N(CH3)2), 5.80 (s, 1H, H-3), 6.12
(s, 2H, NH2, exchangeable with D2O), 7.39 (m, 1H, H-8), 7.50 (m,
1H, H-9), 7.55 (d, 1H, J = 8.0 Hz, H-5), 7.93 (d, 1H, J = 8.0 Hz, H-6),
8.24 (m, 1H, H-7), 8.47 (m, 1H, H-10), 11.98 (s, 1H, NH, exchangeable
with D2O); 13C NMR (DMSO-d6); d (ppm) = 38.3 (N(CH3)2), 83.4 (C-
3), 95.0 (C-4a), 113.5–130.3 (10C, ar), 151.1 (C-4), 152.3 (C-11a),
158.5 (C-2); MS m/z (rel int. %) = 276 (100) [M+], 261 (33), 247
(35), 233 (23), 205 (21); HRMS (C17H16N4) calcd: 276.1375. Found:
276.1375. Anal. Calcd for C17H16N4: C, 73.94; H, 5.84; N, 20.29.
Found: C, 74.12; H, 5.98; N, 20.04.
4.1.2.5. N9,N9,11-Trimethyl-11H-benzo[g]pyrido[2,3-b]indole-
7,9-diamine (7a). This compound was synthesized according to
the general procedure A by refluxing N0-(3-cyano-1-methyl-1H-
benzo[g]indol-2-yl)-N,N-dimethylethanimidamide (6a) (0.10
mmol, 29 mg) and sodium amide (0.28 mmol, 11 mg) in toluene
for 5 h. The product was purified by flash chromatography on silica
gel by using a gradient from 100% cyclohexane to cyclohexane/
ethyl acetate/methanol = 5:4:1 as eluent to yield 14 mg (48%) as
a beige powder. Mp 189–181 °C; IR NaCl:
m
(cmꢀ1) = 3378, 2963,
2923, 2854, 1604; 1H NMR: (DMSO-d6); d (ppm) = 3.10 (s, 6H,
N(CH3)2), 4.35 (s, 3H, OCH3), 5.81 (s, 1H, H-3), 6.20 (s, 2H, NH2,
exchangeable with D2O), 7.44 (m, 1H, H-8), 7.56 (m, 1H, H-9),
7.62 (d, 1H, J = 8.4 Hz, H-5), 8.01 (d, 1H, J = 8.4 Hz, H-6), 8.30 (m,
1H, H-10), 8.71 (m, 1H, H-7); 13C NMR (DMSO-d6); d (ppm) =
31.4 (arN-CH3), 37.9 (N(CH3)2), 83.6 (C-3), 93.9 (C-4a), 117.2 (C-
5), 119.4–130.4 (9C, ar), 150.9 (C-4), 151.8 (C-11a), 158.5 (C-2);
MS m/z (rel int. %) = 290 (100) [M+], 275 (29), 261 (30), 246 (15).
Anal. Calcd for C18H18N4: C, 74.46; H, 6.25; N, 19.29. Found: C,
74.36; H, 6.34; N, 19.42.
4.1.2.8. 2-Amino-1H-indole-3-carbonitrile (10). To a solution of
2-bromonitrobenzene (9) (2.02 g, 10.0 mmol) and malononitrile
(0.66 g, 10.0 mmol) in N-methylpyrrolidone (10 mL) 10 M aqueous
NaOH (3.0 mL) was added dropwise. The mixture was stirred for
50 h at rt. After diluting with DMF (20 mL), a solution of NaHCO3
(7.0 g in 30 mL of water) was added. Then, Na2S2O4 (5.0 g) and
additionnal NaHCO3 (7.0 g) was added and stirred overnight. The
solvents were removed in vacuo and the residue purified by flash
chromatography on silica gel using cyclohexane/ethyl acetate = 3:1
as eluent to yield 0.90 g (57%) as a beige powder. Mp 187–188 °C
4.1.2.6. 11-(4-Methoxybenzyl)-N9,N9-dimethyl-11H-benzo[g]pyr-
ido[2,3-b]indole-7,9-diamine (7b). Alternative 1: This compound
was synthesized according to the general procedure A from N0-[3-
cyano-1-(4-methoxybenzyl)-1H-benzo[g]indol-2-yl]-N,N-dimethy-
lethanimidamide (6b) (0.25 mmol, 99 mg) refluxing for 5 h. The
product was purified by flash chromatography on silica gel by using
a gradient from 100% cyclohexane to cyclohexane/ethyl acetate = 5:5
as eluent to yield 9 mg (9%) as a beige powder. Alternative2: To a solu-
tion of N0-[3-cyano-1-(4-methoxybenzyl)-1H-benzo[g]indol-2-yl]-
N,N-dimethylethanimidamide (6b) (0.05 mmol, 19.8 mg) in abs THF
(0.5 mL) a solution of lithiumdiisopropylamide (2 M in n-hexan,
0.1 mL) was added at ꢀ70 °C in a nitrogen atmosphere. The mixture
was allowed to reach rt overnight with constant stirring. The surplus
of LDA was quenched with a saturated aqueous solution of NaCl and
the organic solvents were distilled off. The suspension was extracted
with ethyl acetate, the organic phase dried with Na2SO4 and evapo-
rated to dryness. The product was purified by flash chromatography
on silica gel by using a gradient from 100% cyclohexane to cyclohex-
ane/ethyl acetate = 5:5 as eluent to yield 11 mg (56%) as a beige pow-
(188 °C)8; IR NaCl:
m
(cmꢀ1) = 3324, 3193, 2190, 1662; 1H NMR:
(DMSO-d6); d (ppm) = 6.70 (s, 2H, NH2, exchangeable with D2O),
6.86–7.32 (m, 4H, H-4, H-5, H-6, H-7), 10.68 (s, 1H, NH, exchange-
able with D2O); 13C NMR (DMSO-d6); d (ppm) = 61.6 (C-3), 110.1
(C-7), 115.0 (C-4), 117.7 (CN), 119.5 (C-5), 120.4 (C-6), 128.2 (C-
3a), 132.0 (C-7a), 153.7 (C-2); MS m/z (rel int. %) = 157 (100)
[M+]. Anal. Calcd for C9H7N3: C, 68.78; H, 4.49; N, 26.73. Found:
C, 68.58; H, 4.32; N, 27.00.
4.1.2.9. N0-(3-Cyano-1H-indol-2-yl)-N,N-dimethylethanimida-
mide (11). A solution of 2-amino-1H-indole-3-carbonitrile (10)
(1.0 mmol, 0.16 g) and 1,1-dimethoxy-N,N-dimethylethanamine
(DMA-DMA, 1.0 mL) in methanol (10 mL) were refluxed for 3 h.
The solvent was removed in vacuo and the product purified by
recrystallization from ethanol to yield 0.16 g (74%) as beige crys-
tals. Mp 166–168 °C; IR NaCl:
m
(cmꢀ1) = 2938, 2202, 1573; 1H
NMR: (DMSO-d6); d (ppm) = 2.09 (s, 3H, H-2), 3.07 and 3.11 (s,
3H, respectively, N(CH3)2), 7.00–7.35 (m, 4H, ar), 11.27 (s, 1H,
der. Mp 195–198 °C; IR NaCl:
m
(cmꢀ1) = 3467, 2950, 2923, 2854,
NH, exchangeable with D2O); 13C NMR (DMSO-d6);
d
1600; 1H NMR: (DMSO-d6); d (ppm) = 3.06 (s, 6H, N(CH3)2), 3.66 (s,
3H, OCH3), 5.86 (s, 1H, H-3), 6.07 (s, 2H, benzyl –CH2–), 6.26 (s, 2H,
NH2, exchangeable with D2O), 6.82 (m, 2H, H-20, H-60), 7.04 (m, 2H,
H-30, H-50), 7.35 (m, 2H, H-5, H-8), 7.63 (m, 1H, H-9), 7.95 (m, 1H, H-
6), 8.35 (m, 2H, H-7, H-10); 13C NMR (DMSO-d6); d (ppm) = 37.8
(N(CH3)2), 45.6 (benzyl CH2), 54.8 (OCH3), 84.0 (C-3), 93.8 (C-4a),
113.9 (C-30, C-50), 117.9-130.6 (13C, ar), 151.0 and 152.2 (C-4, C-
11a), 158.0 and 158.6 (C-2, C-40); MS m/z (rel int. %) = 396 (100)
[M+], 275 (89), 260 (14), 246 (35), 121 (49); HRMS (C25H24N4O) calcd:
(ppm) = 16.1 (C-2), 37.3 (N(CH3)2), 71.0 (C-30), 110.7 (C-70), 116.4
(C-40), 117.8 (CN), 120.5 (C-50), 120.9 (C-60), 127.6 (C-3a), 132.7
(C-7a0), 155.6 (C-1), 160.9 (C-20); MS m/z (rel int. %) = 226 (100)
[M+], 170 (77), 114 (29). Anal. Calcd for C13H14N4: C, 69.00; H,
6.24; N, 24.76. Found: C, 68.79; H, 6.11; N, 25.01.
4.1.2.10. N0-(3-Cyano-1-methyl-1H-indol-2-yl)-N,N-dimethyleth-
animidamide (12a). To a solution of N0-(3-cyano-1H-indol-2-yl)-
N,N-dimethylethanimidamide (11) (1.0 mmol, 0.23 g) in acetone

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4413
(5 mL) freshly powdered KOH (5.0 mmol, 0.28 g) was added at 0 °C.
The suspension was allowed to stir for 30 min at 0 °C. Thereafter,
methyl iodide (2.0 mmol, 0.28 g) was added dropwise with vigorous
stirring. The mixture was allowed to reach rt and stirred additional
18 h at rt. The solvent was removed in vacuo and the product puri-
fied by flash chromatography on silica gel by using a gradient from
100% cyclohexane to cyclohexane/ethyl acetate = 5:5 as eluent to
yield 0.18 g (77%) as a beige powder.
4.1.2.13. N2,N2,9-Trimethyl-9H-pyrido[2,3-b]indole-2,4-diamine
(13a). Preparation was done according to the general procedure
A from N0-(3-cyano-1-methyl-1H-indol-2-yl)-N,N-dimethylethani-
midamide (12a) (0.40 mmol, 96 mg) refluxing for 5 h. The prod-
uct was purified by flash chromatography on silica gel by using a
gradient from 100% cyclohexane to cyclohexane/ethyl ace-
tate = 5:5 as eluent to yield 70 mg (73%) as a beige powder.
Mp 206–208 °C; IR NaCl:
m
(cmꢀ1) = 3382, 2927, 2877, 1604;
Mp 92–93 °C; IR NaCl:
m
(cmꢀ1) = 2938, 2930, 2198, 1585; 1H
1H NMR: (DMSO-d6); d (ppm) = 3.05 (s, 6H, N(CH3)2), 3.70 (s,
3H, N-CH3), 5.67 (s, 1H, H-3), 6.08 (s, 2H, NH2, exchangeable
with D2O), 7.03–7.36 (m, 3H, ar), 8.01 (m, 1H, ar); 13C NMR
(DMSO-d6); d (ppm) = 27.0 (arN-CH3), 37.8 (N(CH3)2), 82.7 (C-
3), 92.8 (C-4a), 107.8 (C-8), 118.8 (C-6), 119.2 (C-5), 121.2 (C-
4b), 121.4 (C-7), 137.3 (C-9a), 151.0 (C-4), 152.7 (C-8a), 159.0
(C-2); MS m/z (rel int. %) = 240 (100) [M+], 225 (55), 211 (65),
196 (32). Anal. Calcd for C14H16N4: C, 69.97; H, 6.71; N, 23.31.
Found: C, 70.17; H, 6.56; N, 23.06.
NMR: (DMSO-d6); d (ppm) = 2.11 (s, 3H, H-2), 3.12 and 3.14 (s,
3H, respectively, N(CH3)2), 3.49 (s, 3H, arN-CH3), 7.11 (m, 2H, H-
5, H-6), 7.36 (m, 2H, H-4, H-7); 13C NMR (DMSO-d6);
d
(ppm) = 16.2 (C-2), 28.2 (arN-CH3), 37.4 and 38.3 (N(CH3)2), 70.0
(C-30), 109.6 (C-70), 116.4 (C-40), 117.8 (CN), 120.9 (2C; C-50, C-60),
126.5 (C-3a), 133.8 (C-7a), 155.1 (C-1), 161.1 (C-20); MS m/z (rel
int. %) = 240 (100) [M+], 225 (17), 196 (14), 184 (43), 169 (17),
157 (15), 114 (35). Anal. Calcd for C14H16N4: C, 69.97; H, 6.71; N,
23.31. Found: C, 70.21; H, 6.63; N, 23.45.
4.1.2.14. 9-(4-Methoxybenzyl)-N2,N2-dimethyl-9H-pyrido[2,3-
b]indole-2,4-diamine (13b). This compound was synthesized
according to general procedure A from N0-[3-cyano-1-(4-methoxy-
benzyl)-1H-indol-2-yl]-N,N-dimethylethanimidamide (12b) (0.50
mmol, 0.13 g) by refluxing for 5 h. The product was purified by
flash chromatography on silica gel by using a gradient from 100%
cyclohexane to cyclohexane/ethyl acetate = 6:4 as eluent to yield
4.1.2.11. N0-[3-Cyano-1-(4-methoxybenzyl)-1H-indol-2-yl]-N,N-
dimethylethanimidamide (12b). A solution of N0-(3-cyano-1H-
indol-2-yl)-N,N-dimethylethanimidamide (11) (2.0 mmol, 0.45 g)
in acetone (10 mL) was treated with freshly powdered KOH
(10.0 mmol, 0.56 g) with vigorous stirring and cooling if necessary.
After careful addition of 4-methoxybenzylbromide (4.0 mmol,
0.80 g) the mixture was stirred for 2 h at rt. The insoluble salts
were filtered off and the solvent was removed in vacuo. The prod-
uct was purified by flash chromatography on silica gel by using a
gradient from 100% cyclohexane to cyclohexane/ethyl ace-
tate = 9:1 as eluent to yield 0.43 g (62%) as a beige powder. Mp
0.14 g (82%) as beige crystals. Mp 155–156 °C; IR NaCl:
m
(cmꢀ1) = 2286, 2927, 2834, 1612, 1600; 1H NMR: (DMSO-d6); d
(ppm) = 3.06 (s, 6H, N(CH3)2), 3.67 (s, 3H, OCH3), 5.40 (s, 2H, benzyl
–CH2–), 5.71 (s, 1H, H-3), 6.11 (s, 2H, NH2, exchangeable with D2O),
6.75–7.37 and 8.01 (m respectively, 8H, ar); 13C NMR (DMSO-d6); d
(ppm) = 37.8 (N(CH3)2), 43.1 (CH2), 54.9 (OCH3), 82.9 (C-3), 92.7 (C-
4a), 108.4 (C-8), 113.4 (C-5), 113.7 (C-30, C-50), 118.6 (C-6), 119.3
(C-5a), 121.5 (C-7), 128.8 (C-20, C-60), 134.4 (C-10), 136.3 (C-8a),
151.0 (C-4), 152.4 (C-9a), 158.2 (C-40), 159.0 (C-2); MS m/z (rel
int. %) = 346 (100) [M+], 331 (26), 317 (17), 225 (11), 196 (15),
121 (100). Anal. Calcd for C21H22N4O: C, 72.81; H, 6.40; N, 16.17.
Found: C, 72.88; H, 6.23; N, 16.36.
123–126 °C; IR NaCl:
m
(cmꢀ1) = 2931, 2198, 1585; 1H NMR:
(DMSO-d6); d (ppm) = 2.07 (s, 3H, H-2), 3.12 and 3.13 (s, 3H,
respectively, N(CH3)2), 3.68 (s, 3H, OCH3), 5.17 (s, 2H, –CH2–),
6.85 (m, 2H, H-200, H-600), 7.07 (m, 2H, H-50, H-60), 7.16 (m, 2H,
H-300, H-500), 7.36 (m, 2H, H-40, H-70); 13C NMR (DMSO-d6); d
(ppm) = 16.0 (C-2), 37.4 and 38.4 (N(CH3)2), 55.0 (CH2 and
OCH3), 70.3 (C-30), 110.1 (C-70), 113.9 (C-300, C-500), 116.6 (CN),
117.7 (C-40), 121.0 (C-50, C-60), 126.7 (C-3a0), 128.5 (C-200, C-600),
129.4 (C-100), 133.0 (C-8a0), 154.9 (C-400), 158.4 (C-1), 161.3 (C-
20); MS m/z (rel int. %) = 346 (51) [M+], 225 (30), 121 (100). Anal.
Calcd for C21H22N4O: C, 72.81; H, 6.40; N, 16.17. Found: C, 73.15;
H, 6.22; N, 15.94.
4.1.2.15. 9-(Diethoxymethyl)-N2,N2-dimethyl-9H-pyrido[2,3-
b]indole-2,4-diamine (13c). Preparation was according to the
general procedure A from N0-[3-cyano-1-(diethoxymethyl)-1H-in-
dol-2-yl]-N,N-dimethylethanimidamide (12c) (0.25 mmol, 82 mg)
refluxing for 30 min. The product was purified by flash chromatog-
raphy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate/methanol = 65:30:5 as eluent to yield
4.1.2.12. N0-[3-Cyano-1-(diethoxymethyl)-1H-indol-2-yl]-N,N-
dimethylethanimidamide
(12c). N0-(3-Cyano-1H-indol-2-yl)-
N,N-dimethylethanimidamide (11) (0.4 mmol, 90.5 mg) was dis-
solved in triethyl orthoformate (5 mL) and heated at 160 °C for
48 h. Excess orthoester was distilled off and the residue dissolved
in a small volume of ethanol and cooled overnight. The crystallized
product was collected; further product could be achieved by distill-
ing off the filtrate and purifying the residue by flash chromatogra-
phy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate/methanol = 5:4:1 as eluent to yield
35 mg (43%) as a beige powder. Mp 101–102 °C; IR NaCl:
(cmꢀ1) = 3382, 2977, 2935, 2904, 2884, 1607, 1600; 1H NMR:
(DMSO-d6); (ppm) = 1.14 (m, 6H, acetal-CH3), 3.05 (s, 6H,
N(CH3)2), 3.38–3.74 (m, 4H, acetal-CH2–), 5.73 (s, 1H, H-3), 6.15
(s, 2H, NH2, exchangeable with D2O), 6.89 (s, 1H, acetal-CH–),
7.12 (m, 2H, ar), 7.66 (m, 1H, ar), 8.02 (m, 1H, ar); 13C NMR
m
d
(DMSO-d6);
d (ppm) = 14.6 (OCH2–CH3), 37.7 (N(CH3)2), 61.7
(OCH2–CH3), 83.3 (C-3), 92.6 (C-4a), 100.0 (acetal-CH), 112.0 (C-
8), 119.2 (C-5), 119.6 (C-6), 121.5 (C-7), 122.1 (C-4b), 133.9 (C-
9a), 151.1 (C-4), 152.3 (C-8a), 158.7 (C-2); MS m/z (rel int.
%) = 328 (18) [M+], 282 (18), 254 (22), 226 (100), 211 (31), 197
(28), 183 (20), 155 (19). Anal. Calcd for C18H24N4O2: C, 65.83; H,
7.37; N, 17.06. Found: C, 65.89; H, 7.43; N, 17.43.
90 mg (68%) as a grey powder. Mp 140–141 °C; IR NaCl:
m
(cmꢀ1) = 2977, 2931, 2892, 2210, 1579, 1589; 1H NMR: (DMSO-
d6); d (ppm) = 1.13 (t, 6H, J = 7.2 Hz, O–CH2–CH3), 2.16 (s, 3H, H-
2), 3.13 and 3.17 (s, 3H, respectively, N(CH3)2), 3.37–3.71 (m, 4H,
J = 7.2 Hz, O–CH2–CH3), 6.31 (s, 1H, CH acetal), 7.06–7.17 (m, 2H,
H-50, H-60), 7.36 (m, 1H, H-40), 7.62 (m, 1H, H-70); 13C NMR
(DMSO-d6);
d
(ppm) = 14.5 (OCH2–CH3), 16.0 (C-2), 37.4
4.1.2.16. N2,N2-Dimethyl-9H-pyrido[2,3-b]indole-2,4-diamine
(14). Alternative 1: This compound was synthesized according to
the general procedure A by refluxing N0-[3-cyano-1-(diethoxym-
ethyl)-1H-indol-2-yl]-N,N-dimethylethanimidamide (12b) (0.25
mmol, 82 mg) and sodium amide (0.63 mmol, 24 mg) in toluene
for 30 min. This compound, representing a side product of reaction
5.1.8., was purified by flash chromatography on silica gel by using a
(N(CH3)2), 61.9 (OCH2–CH3), 70.9 (C-30), 100.7 (acetal-CH), 112.9
(C-70), 116.4 (C-40), 117.2 (CN), 121.3 and 121.4 (C-5 and C-6),
126.6 (C-3a), 130.7 (C-7a), 154.5 (C-20), 161.3 (C-1); MS m/z (rel
int. %) = 328 (30) [M+], 254 (21), 226 (82), 170 (32), 155 (21), 114
(26), 103 (100), 75 (67). Anal. Calcd for C18H24N4O2: C, 65.83; H,
7.37; N, 17.06. Found: C, 65.66; H, 7.02; N, 16.89.

4414
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
gradient from 100% cyclohexane to cyclohexane/ethyl acetate/
methanol = 65:30:5 as eluent to yield 19 mg (34%) as a beige pow-
der. Alternative 2: 9-(4-Methoxybenzyl)-N2,N2-dimethyl-9H-pyr-
ido[2,3-b]indole-2,4-diamine (13b) (0.25 mmol, 87 mg), anisole
(0.5 mL), trifluoroacetic acid (5 mL) and concd sulfuric acid
(0.25 mL) were stirred for 90 min at rt. The mixture was poured
onto ice and then a saturated aqueous solution of NaHCO3
(80 mL) was carefully added. The mixture was allowed to stand
at rt overnight and the next day it was extracted with ethyl acetate.
The organic phase was dried with Na2SO4 and evaporated to dry-
ness. The product was purified by flash chromatography on silica
gel by using a gradient from 100% cyclohexane to cyclohexane/
ethyl acetate = 5:5 as eluent to yield 42 g (74%) as a beige powder.
(C-40), 21.2 (C-70), 22.5 (C-50), 22.6 (C-60), 37.5 and 38.4 (N(CH3)2),
44.8 (–CH2–), 76.4 (C-30), 115.4 (C-3a0), 118.4 (–CN), 123.1 (C-7a0),
126.7 (C-200), 127.0 (C-600), 127.8 (C-400), 128.5 (C-300, C-500), 138.4 (C-
100), 147.8 (C-20), 160.2 (C-1); MS m/z (rel int. %) = 320 (77) [M+], 229
(85), 91 (100). Anal. Calcd for C20H24N4: C, 74.97; H, 7.55; N, 17.48.
Found: C, 74.85; H, 7.33; N, 17.23.
4.1.2.19. N0-(1-Benzyl-3-cyano-4,5-dimethyl-1H-pyrrol-2-yl)-N,N-
dimethylethanimidamide (16b). Alternative 1: 2-Amino-1-benzyl-
4,5-dimethyl-1H-pyrrole-3-carbonitrile (15b) (5.0 mmol, 1.13 g) was
refluxed in 1,1-dimethoxy-N,N-dimethylethanamine (DMA-DMA,
3.0 mL) for 2 h. After distillation of the solvent, the residue was crystal-
lized from toluene to yield 0.38 g (26%) as beige crystals. Alternative 2:
Preparation as described for 16a with 2-amino-1-benzyl-4,5-di-
methyl-1H-pyrrole-3-carbonitrile (15b) (0.1 mol, 22.5 g) to yield
Mp 74–75 °C; IR NaCl:
m
(cmꢀ1) = 3382, 3201, 2927, 2854, 1612,
1585; 1H NMR: (DMSO-d6); d (ppm) = 3.01 (s, 6H, N(CH3)2), 5.66
(s, 1H, H-3), 6.17 (s, 2H, NH2, exchangeable with D2O), 6.99 and
7.08 (m, 1H, respectively, H-6 and H-7), 7.20 (m, 1H, H-8), 7.96
(m, 1H, H-5), 10.95 (s, 1H, NH, exchangeable with D2O); 13C NMR
(DMSO-d6); d (ppm) = 38.0 (N(CH3)2), 82.7 (C-3), 93.3 (C-4a),
109.4 (C-8), 118.3 (C-5), 119.2 (C-7), 121.3 (C-6), 121.8 (C-4b),
136.1 (C-8a), 150.8 (C-9a), 153.2 (C-4), 159.2 (C-2); MS m/z (rel
int. %) = 226 (100) [M+], 211 (54), 197 (59), 183 (28), 155 (30),
113 (15). Anal. Calcd for C13H14N4: C, 69.00; H, 6.24; N, 24.76.
Found: C, 69.06; H, 6.45; N, 24.44.
10.3 g (35%) as beige crystals. Mp 131–132 °C; IR NaCl:
m
(cmꢀ1) =
2920, 2196, 1592, 1434; 1H NMR: (DMSO-d6); d (ppm) = 1.96 (m, 6H,
40,50-dimethyl), 1.98 (s, 3H, H-2), 3.00 (s, 6H, N-(CH3)2), 4.92 (s, 2H,
–CH2–), 7.01–7.39 (m, 5H, ar); 13C NMR (DMSO-d6); d (ppm) = 10.0
(CH3 at C-40), 10.2 (CH3 at C-50), 15.9 (C-2), 37.5 and 38.6 (N(CH3)2),
45.6 (CH2) 79.2 (C-30), 112.9 (C-40), 119.1 (CN), 120.5 (C-50), 126.9
(C-200, C-600), 127.4 (C-400), 129.0 (C-300, C-500), 138.8 (C-100), 147.9
(C-20), 160.7 (C-1); MS m/z (rel int. %) = 294 (73) [M+], 203 (100). Anal.
Calcd for C18H22N4: C, 73.44; H, 7.53; N, 19.03. Found: C, 73.18; H, 7.52;
N, 18.94.
4.1.2.17. 1-Allyl-2-amino-4,5-diphenyl-1H-pyrrole-3-carbonitrile
(15c). Benzoine (0.10 mmol, 21.2 g), allylamine (0.10 mmol, 5,71 g)
and a catalytical amount of p-toluenesulfonic acid in toluene
(75 mL) were refluxed in a Dean Stark apparatus for 1 h. The warm
reaction mixture was then carefully added to a suspension of
malononitrile (0.10 mmol, 6.61 g) in toluene (20 mL) at 90 °C and
allowed to reflux an additional 45 min. After evaporation to dryness,
the product crystallized from ethanol to yield 13.7 g (46%) as beige
4.1.2.20. N0-(1-Allyl-3-cyano-4,5-diphenyl-1H-pyrrol-2-yl)-N,N-
dimethylethanimidamide (16c). Preparation as described for
16a from 1-allyl-2-amino-4,5-diphenyl-1H-pyrrole-3-carbonitrile
(15c) (9.1 mmol, 2.7 g) to yield 2.14 g (64%) as beige crystals. Mp
130–131 °C; IR NaCl:
m
(cmꢀ1) = 2929, 2202, 1590; 1H NMR:
(DMSO-d6); d (ppm) = 2.13 (s, 3H, CH3), 3.08 (s, 6H, N(CH3)2), 4.27
(m, 2H, H-10), 4.67 (m, 1H, H-30 Z), 4,99 (m, 1H, H-30 E), 5.62–5.78
(m, 1H, H-20), 7.09–7.44 (m, 10H, ar); 13C NMR (DMSO-d6); d
(ppm) = 15.7 (C-2), 37.1 and 38.2 (N(CH3)2), 44.7 (C-100), 78.9 (C-
30), 115.6 (C-300), 118.3 (CN), 120.2 (C-40), 125.9–131.0 (12C, Ar),
133.5 (C-50), 134.3 (C-200), 149.4 (C-20), 160.5 (C-1); MS m/z (rel int.
%) = 368 (100) [M+], 327 (92). Anal. Calcd for C24H24N4: C, 78.23; H,
6.57; N, 15.20. Found: C, 77.95; H, 6.53; N, 15.10.
crystals. Mp 156–158 °C; IR NaCl:
m
(cmꢀ1) = 3332, 3230, 3052,
1
2201, 1628; H NMR: (DMSO-d6); d (ppm) = 4.29 (m, 2H, H-10),
4.76 (m, 1H, H-30 Z), 5.07 (m, 1H, H-30 E), 5.72 (m, 1H, H-20), 6.04
(s, 2H, NH2, exchangeable with D2O), 7.06–7.38 (m, 10H, phenyl);
13C NMR (DMSO-d6); d (ppm) = 44.5 (C-10), 70.4 (C-3), 115.9 (C-30),
118.0 (CN), 119.7 (C-1000), 123.4 (C-4), 126.0 (C-4000), 127.8 (C-400),
128,4 (C-2000, C-6000), 128.5 (C-300, C-500, C-3000, C-5000), 130.9 (C-200, C-
600), 131.0 (C-100), 133.2 (C-20), 133.6 (C-5), 148.3 (C-2); MS m/z
(rel int. %) = 299 (63) [M+], 258 (100). Anal. Calcd for C20H17N3: C,
80.24; H, 5.72; N, 14.04. Found: C, 79.94; H, 5.77; N, 13.84.
4.1.2.21. N0-(1-Benzyl-3-cyano-4,5-diphenyl-1H-pyrrol-2-yl)-N,N-
dimethylethanimidamide (16d). Preparation as described for
16a from 2-amino-1-benzyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile
(15d) (20 mmol, 7.0 g) to yield 4.35 g (52%) as a beige powder. Mp
4.1.2.18. N0-(1-Benzyl-3-cyano-4,5,6,7-tetrahydro-1H-indol-2-yl)-
N,N-dimethylethanimidamide (16a). Alternative 1: 2-Amino-1-
benzyl-4,5,6,7-tetrahydro-1H-indole-3-carbonitrile (15a) (3.0 mmol,
0.75 g) was refluxed in 1,1-dimethoxy-N,N-dimethylethanamine
(DMA-DMA, 3.0 mL) for 5 h. After evaporation to dryness, the product
was purified by flash chromatography on silica gel by using cyclohex-
ane/ethyl acetate = 85:15 as eluent to yield 0.48 g (47%) as beige
crystals. Alternative 2: Phosphorus oxychloride (0.2 mL) and N,N-
dimethylacetamide (6.0 mmol, 0.53 g) were solved in chloroform
(3 mL). After stirring for 6 min, 2-amino-1-benzyl-4,5,6,7-tetrahydro-
1H-indole-3-carbonitrile (15a) (1.0 mmol, 0.25 g) was added carefully
and refluxed for 5 h. The mixture was allowed to cool down at rt and
then pipetted into ice water. After adjusting pH >9 the mixture was ex-
tracted with ethyl acetate. The organic layers were dried with Na2SO4
and evaporated to dryness. The product was purified by flash chroma-
tography on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate = 5:5 as eluent to yield 0.14 g (44%) as beige
144–146 °C; IR NaCl: m
(cmꢀ1) = 2930, 2202, 1589, 145; 1H NMR:
(DMSO-d6); d (ppm) = 1.97 (s, 3H, H-2), 3.02 (s, 6H, N(CH3)2), 4.92
(s, 2H, CH2), 6.83–7.40 (m, 15H, ar); 13C NMR (DMSO-d6); d
(ppm) = 15.6 (C-2), 37.1 and 38.1 (N-CH3)2), 45.8 (CH2), 78.5 (C-30),
118.2 (CN), 120.4 (C-40), 126.1–133.4 (18C, ar), 138.0 (C-50), 149.6
(C-20), 160.7 (C-1); MS m/z (rel int. %) = 418 (100) [M+], 327 (100).
Anal. Calcd for C28H26N4: C, 80.35; H, 6.26; N, 13.39. Found: C,
80.53; H, 6.06; N, 13.43.
4.1.2.22. 9-Benzyl-N2,N2-dimethyl-5,6,7,8-tetrahydro-9H-pyrido
[2,3-b]indole-2,4-diamine (17a). A suspension of N0-(1-benzyl-3-
cyano-4,5,6,7-tetrahydro-1H-indol-2-yl)-N,N-dimethylethanimida-
mide (16a) (4.2 mmol, 1.4 g) and NaH (60% supension in mineral oil,
7.5 mmol) in abs dioxane (15 mL) was refluxed for 2 h. The surplus
of sodium hydride was quenched with methanol followed by water
and the alcohol was distilled off. The aqueous suspension was ex-
tracted with diethyl ether, the organic layer dried with Na2SO4 and
the solvent removed in vacuo. The residue was purified by flash chro-
matography on silica gel by using a gradient from 100% cyclohexane
to cyclohexane/ethyl acetate = 7:3 as eluent to yield 0.49 g (35%) as
crystals. Mp 107–108 °C; IR NaCl:
m
(cmꢀ1) = 2937, 2873, 2196, 1631,
1589; 1H NMR: (DMSO-d6); d (ppm) = 1.61–1.73 (m, 4H, H-5, H-6),
1.93 (s, 3H, H-200), 2.30–2.39 (m, 4H, H-4, H-7), 3,00 (s, 6H, N(CH3)2),
4.81 (s, 2H, –CH2–), 7.06 (m, 2H, H-200, H-600), 7.23 (m, 1H, H-400), 7.30
(m, 2H, H-300, H-500); 13C NMR (DMSO-d6); d (ppm) = 15.9 (C-2), 21.0
a beige powder. Mp 139–140 °C (dec); IR NaCl:
2925, 2848, 1608, 1571; 1H NMR: (DMSO-d6); d (ppm) = 1.64–1.79
m
(cmꢀ1) = 3378,

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4415
(m, 4H, H-6, H-7), 2.44–2.80 (m, 4H, H-5, H-8), 2.93 (s, 6H, N(CH3)2),
5.14 (s, 2H, benzyl –CH2–), 5.33 (s, 2H, NH2, exchangeable with
D2O), 5.56 (s, 1H, H-3), 7.14–7.29 (m, 5H, ar); 13C NMR (DMSO-d6); d
(ppm) = 21.9 and 22.7 (C-5, C-8), 22.8 and 23.5 (C-6, C-7), 38.6
(N(CH3)2), 44.1 (benzyl –CH2), 84.1 (C-3), 100.0 (C-4a), 106.9 (C-4b),
127.4 (C-20, C-60), 127.5 (C-40), 128.8 (C-30, C-50), 130.5 (C-10), 140.0
(C-8a), 148.3 (C-9a), 149.8 (C-4), 157.3 (C-2); MS m/z (rel int.
%) = 320 (100) [M+], 229 (67). Anal. Calcd for C20H24N4: C, 74.97; H,
7.55; N, 17.48. Found: C, 75.26; H, 7.25; N, 17.67.
C28H26N4: C, 80.35; H, 6.26; N, 13.39. Found: C, 80.07; H 6.40; N,
13.67.
4.1.2.26. N0-(3-Cyano-4,5,6,7-tetrahydro-1-benzothien-2-yl)-
N,N-dimethylethanimidamide (20a). According to general pro-
cedure B, this compound was obtained from 2-amino-4,5,6,7-tetra-
hydro-1-benzothiophene-3-carbonitrile (18a) (10.0 mmol, 1.78 g)
after 5 h. The solvents were removed in vacuo and the product
purified by flash chromatography on silica gel by using a gradient
from 100% cyclohexane to cyclohexane/ethyl acetate = 96:4 as
eluent to yield an orange oil that solidified in n-hexane in an ultra-
sonic bath as 1.83 g (74%) of a beige-orange powder. Mp 79–80 °C;
4.1.2.23. 1-Benzyl-N6,N6,2,3-tetramethyl-1H-pyrrolo[2,3-b]pyri-
dine-4,6-diamine (17b). Preparation was analogous to 17a from
N0-(1-benzyl-3-cyano-4,5-dimethyl-1H-pyrrol-2-yl)-N,N-dimethy-
lethanimidamide (16b) (30.6 mmol, 9.0 g). After cooling to rt the
surplus of sodium hydride was quenched with methanol and then
the solvents were removed in vacuo. Thereafter, water was added
and the pH adjusted to >9. The suspension was extracted with
diethyl ether and the organic layer dried with Na2SO4. The residue
was purified by flash chromatography on silica gel by using a gra-
dient from 100% cyclohexane to cyclohexane/ethyl acetate = 9:1 as
eluent. The powder obtained crystallized from ethanol to yield
IR NaCl:
m
(cmꢀ1) = 2931, 2844, 2204, 1583, 1442; 1H NMR:
(DMSO-d6); d (ppm) = 1.75 (m, 4H, H-50, H-60), 2.08 (s, 3H, H-2),
2.41–2.55 (m, 4H, H-40, H-70), 3.04 (s, 6H, N(CH3)2); 13C NMR
(DMSO-d6); d (ppm) = 14.9 (C-2), 22.8 (C-60), 22,9 (C-50), 23.8 (C-
70), 23.9 (C-40), 37.8 (2C, N(CH3)2), 95.5 (C-30), 115.9 (CN), 125,1
(C-7a), 131.8 (C-3a), 159.9 (C-1), 163.9 (C-20); MS m/z (rel int.
%) = 247 (100) [M+], 232 (38), 219 (37), 214 (28), 203 (35), 191
(68). Anal. Calcd for C13H17N3S: C, 63.12; H, 6.93; N, 16.99; S,
12.96. Found: C, 62.93; H, 6.85; N, 16.72; S, 13.06.
4.94 g (55%) as beige crystals. Mp 136–138 °C; IR NaCl:
m
(cmꢀ1) = 1648, 3374, 2922, 1859, 1606, 1570, 1440; 1H NMR:
(DMSO-d6); d (ppm) = 2.07 (s, 3H, C-5–CH3), 2.26 (s, 3H, C-6–
CH3), 2.92 (s, 6H, N-(CH3)2), 5.21 (s, 2H, –CH2–), 5.39 (s, 2H, NH2,
exchangeable with D2O), 5.59 (s, 1H, H-3), 7.10 (m, 2H, H-20, H-
60), 7.20 (m, 1H, H-40), 7.26 (m, 2H, H-30, H-50); 13C NMR (DMSO-
d6); d (ppm) = 9.3 (C-5–CH3), 10.9 (C-6–CH3), 38.0 (N(CH3)2), 43.8
(CH2), 83.8 (C-3), 100.2 (C-4a), 103.6 (C-5), 123.9 (C-6), 126.6 (C-
40), 126.7 (C-20, C-60), 128.2 (C-30, C-50), 139.6 (C-10), 147.9 (C-7a),
149.6 (C-4), 156.7 (C-2); MS m/z (rel int. %) = 294 (100) [M+], 203
(91), 187 (15), 174 (14), 162 (29). Anal. Calcd for C18H22N4: C,
73.44; H, 7.53; N, 19.03. Found: C, 73.69; H, 7.48; N, 18.90.
4.1.2.27. N0-(3-Cyano-4-methyl-5-phenyl-2-thienyl)-N,N-dime-
thylethanimidamide (20c). Preparation was according to general
procedure B from 2-amino-4-methyl-5-phenylthiophene-3-carbo-
nitrile (18c) (3.0 mmol, 0.64 g) after 3 h. The solvents were
removed in vacuo and the residue purified by crystallization from
ethanol to yield 0.38 g (29%) as a beige powder. Mp 141–143 °C; IR
NaCl:
(ppm) = 2.20 (s, 3H, H-2), 2.27 (s, 3H, CH3 at C-40), 3.10 (s, 6H,
N(CH3)2), 7.32–7.52 (m, 5H, ar); 13C NMR (DMSO-d6);
m d
(cmꢀ1) = 2923, 2206, 1577; 1H NMR: (DMSO-d6);
d
(ppm) = 14.0 (CH3 at C-4), 15.1 (C-2), 37.9 (N(CH3)2), 99.4 (C-30),
116.2 (CN), 126.3 (C-50), 127.3 (C-400), 128.3 (C-200, C-600), 128.5
(C-300, C-500), 130.3 (C-40), 133.1 (C-100), 160.3 (C-1), 164.6 (C-20);
MS m/z (rel int. %) = 283 (100) [M+], 268 (27), 239 (24), 227 (93).
Anal. Calcd for C16H17N3S: C, 67.81; H, 6.05; N, 14.38; S, 11.31.
Found: C, 67.72; H, 5.81; N, 14.15; S, 11.56.
4.1.2.24. 1-Allyl-N6,N6-dimethyl-2,3-diphenyl-1H-pyrrolo[2,3-
b]pyridine-4,6-diamine (17c). This compound was synthesized
according to the general procedure A from N0-(1-allyl-3-cyano-4,5-
diphenyl-1H-pyrrol-2-yl)-N,N-dimethylethanimidamide (16c) (3.0
mmol, 1.11 g) refluxing for 3 h. The residue was purified by flash
chromatography on silica gel by using a gradient from 100% cyclo-
hexane to cyclohexane/ethyl acetate = 5:5 as eluent to yield 0.41 g
4.1.2.28. N0-(3-Cyano-4,5-diphenyl-2-thienyl)-N,N-dimethyleth-
animidamide (20e). Preparation was according to the general
procedure B from 2-amino-4,5-diphenylthiophene-3-carbonitrile
(18e) (2.46 mmol, 0.68 g) after 5 h. The solvents were removed in
vacuo and the residue purified by crystallization from ethanol to
(37%) as a beige powder. Mp 104–106 °C; IR NaCl:
m
(cmꢀ1) = 3484,
3380, 2923, 2848, 1596; 1H NMR: (DMSO-d6); d (ppm) = 2.99 (s,
6H, N(CH3)2), 4.63 (m, 2H, H-10), 4.75 (m, 1H, H-20 Z), 4.94 (s, 2H,
NH2, exchangeable with D2O), 4.97 (m, 1H, H-20 E), 5.67 (s, 1H, H-
3), 5.78–5.86 (m, 1H, H-30), 7.12–7.34 (m, 10H, ar); 13C NMR
(DMSO-d6); d (ppm) = 38.5 (N(CH3)2), 44.5 (C-10), 84.6 (C-3), 99.5
(C-4a), 113.5 (C-5), 116.3 (C-30), 126.9–132.0 (12C, ar), 135.2 (C-20),
136.3 (C-6), 148.3 (C-7a), 149.6 (C-4), 158.1 (C-2); MS m/z (rel int.
%) = 368 (100) [M+], 327 (28), 286 (20). Anal. Calcd for C24H24N4: C,
78.23; H, 6.57; N, 15.20. Found: C, 78.25; H, 6.72; N, 15.44.
yield 0.49 g (58%) as a beige powder. Mp 190–194 °C; IR NaCl:
m
(cmꢀ1) = 2931, 2210, 1575; 1H NMR: (DMSO-d6); d (ppm) = 2.24
(s, 3H, H-2), 3.10 (s, 6H, N(CH3)2), 7.08–7.43 (m, 10H, ar); 13C
NMR (DMSO-d6); d (ppm) = 15.2 (C-2), 38.0 (N(CH3)2), 99.4 (C-30),
116.0 (CN), 127.2–135.2 (14C, C-40, C-50, ar), 160.5 (C-1), 165.2
(C-20); MS m/z (rel int. %) = 345 (100) [M+], 332 (22), 289 (25). Anal.
Calcd for C21H19N3S: C, 73.01; H, 5.54; N, 12.16; S, 9.28. Found: C,
73.25; H, 5.35; N, 12.02; S, 9.37.
4.1.2.25. 1-Benzyl-N6,N6-dimethyl-2,3-diphenyl-1H-pyrrolo[2,3-
b]pyridine-4,6-diamine (17d). Preparation was according to the
general procedure A from N0-(1-benzyl-3-cyano-4,5-diphenyl-1H-
pyrrol-2-yl)-N,N-dimethylethanimidamide (16d) (0.22 mmol, 90
mg) refluxing for 3 h. The residue was purified by recrystallization
from ethanol to yield 62 mg (69%) as a beige powder. Mp 128–
4.1.2.29.
animidamide (21b). Preparation was according to the general
procedure from 2-amino-4,5-dimethyl-3-furonitrile (19b)
N0-(3-Cyano-4,5-dimethyl-2-furyl)-N,N-dimethyleth-
B
(5.0 mmol, 0.68 g) after 5 h. The solvents were removed in vacuo
and the residue purified by flash chromatography on silica gel by
using a gradient from 100% cyclohexane to cyclohexane/ethyl ace-
tate = 85:15 as eluent to yield 0.20 g (19%) as an orange powder.
129 °C (dec); IR NaCl:
m
(cmꢀ1) = 3388, 2929, 1596; 1H NMR:
(DMSO-d6); d (ppm) = 2.98 (s, 6H, N-(CH3)2), 4.99 (s, 2H, NH2,
exchangeable with D2O), 5.25 (s, 2H, CH2), 5.69 (s, 1H, H-3), 6.90–
7.30 (m, 15H, ar); 13C NMR (DMSO-d6); d (ppm) = 38.0 (N(CH3)2),
44.9 (CH2), 84.1 (C-3), 99.5 (C-4a), 113.3 (C-5), 126.2–131.5 (18C,
ar), 139.0 (C-6), 148.0 (C-7a), 149.4 (C-4), 157.4 (C-2); MS m/z (rel
int. %) = 418 (100) [M+], 327 (51), 286 (30). Anal. Calcd for
Mp 60–61 °C; IR NaCl: m
(cmꢀ1) = 2923, 2210, 1592; 1H NMR:
(DMSO-d6); d (ppm) = 1.91 (m, 3H, 50-CH3), 2.11 (m, 3H, 40-CH3),
2.12 (s, 3H, H-2), 3.04 and 3.10 (N(CH3)2); 13C NMR (DMSO-d6); d
(ppm) = 9.0 (CH3 at C-40), 11.3 (CH3 at C-50), 17.1 (C-2), 38.0 and
38.8 (N(CH3)2), 80.4 (C-30), 114.2 (CN), 116.9 (C-40), 140.3 (C-50),
162.0 (C-1), 163.7 (C-20); MS m/z (rel int. %) = 205 (94) [M+], 162

4416
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
(100). Anal. Calcd for C11H15N3O: C, 64.37; H, 7.37; N, 20.47. Found:
C, 64.14; H, 7.09; N, 20.61.
4.1.2.34. 4,5-Diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-
thiophene-3-carbonitrile (24e). Ethyl N-(3-cyano-4,5-diphenyl-
2-thienyl)ethanimidoate (22e) (0.75 mmol, 0.26 g) was stirred in
pyrrolidine (5 mL) at rt for 30 min. The yellow precipitate was fil-
tered off and washed with cold ethanol to yield 0.24 g (84%) of yel-
4.1.2.30. N0-(3-Cyano-4,5-diphenyl-2-furyl)-N,N-dimethyleth-
animidamide (21e). Preparation was according to the general
procedure B from 2-amino-4,5-diphenyl-3-furonitrile (19e) (0.5
mmol, 0.13 g) after 5 h. The solvents were removed in vacuo and
the residue purified by flash chromatography on silica gel by using
a gradient from 100% cyclohexane to cyclohexane/ethyl acetate =
9:1 as eluent to yield 0.12 g (73%) as a beige powder. Mp 110–
low crystals. Mp 206–209 °C; IR NaCl: m
(cmꢀ1) = 2973, 2869, 2206,
1562; 1H NMR: (DMSO-d6); d (ppm) = 1.92 (m, 4H, H-30, H-40), 2.27
(s, 3H, H-2), 3.53 (m, 4H, H-20, H-50), 7.07–7.44 (m, 10H, ar); 13C
NMR (DMSO-d6); d (ppm) = 16.3 (C-2), 39.0–40.0 (C-300, C-400),
47.5 (C-200, C-500), 99.0 (C-30), 116.2 (CN), 126.9–129.4 (11C, ar),
132.8 (C-1000), 134.0 (C-40), 135.2 (C-10000), 158.3 (C-1), 164.8 (C-
20); MS m/z (rel int. %) = 371 (100) [M+], 342 (27), 329 (12), 301
(31). Anal. Calcd for C23H21N3S: C, 74.36; H, 5.70; N, 11.31; S,
8.63. Found: C, 74.24; H, 5.54; N, 11.50; S, 8.59.
111 °C; IR NaCl:
m
(cmꢀ1) = 2923, 2210, 1577; 1H NMR: (DMSO-
d6); d (ppm) = 2.31 (s, 3H, H-2), 3.12 (s, 3H, N-CH3), 3.16 (s, 3H,
N-CH3), 7.19–7.54 (m, 10H, ar); 13C NMR (DMSO-d6); d (ppm) =
17.2 (C-2), 37.8 and 38.6 (N(CH3)2), 81.4 (C-30), 115.6 (C-40),
121.9 (CN), 124.7–131.2 (12C, ar), 140.1 (C-50), 162.4 (C-1), 163.6
(C-20); MS m/z (rel int. %) = 329 (100) [M+], 224 (63). Anal. Calcd
for C21H19N3O: C, 76.57; H, 5.81; N, 12.76. Found: C, 76.38; H,
5.67; N, 12.58.
4.1.2.35. 4,5-Dimethyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-
3-furonitrile (25b).
A solution of methyl N-(3-cyano-4,5-di-
methyl-2-furyl)ethanimidoate (23b) (1.7 mmol, 0.33 g) in pyrroli-
dine (4 mL) was refluxed for 3 h. Excess pyrrolidine was removed
in vacuo and the residue purified by flash chromatography on silica
gel by using a gradient from 100% cyclohexane to cyclohexane/
ethyl acetate = 6:4 as eluent to yield 0.24 g (60%) as a beige pow-
4.1.2.31. Ethyl (1E)-N-(3-cyano-4,5-diphenyl-2-thienyl)ethanim-
idoate (22e). 2-Amino-4,5-diphenylthiophene-3-carbonitrile (18e)
(4.0 mmol, 1.11 g) was heated to reflux in 1,1,1-triethoxyethane
(10 mL) for 5 h. After distillation, the residue was purified by flash
chromatography on silica gel by using a gradient from 100% cyclo-
hexane to cyclohexane/ethyl acetate = 8:2 as eluent to yield 0.99 g
der. Mp 55–57 °C; IR NaCl:
m
(cmꢀ1) = 2973, 2950, 2923, 2873,
1
2206; H NMR: (DMSO-d6); d (ppm) = 1.82–1.95 (m, 7H, H-300, H-
400, H-2), 2.09 and 2.12 (s, 3H, respectively, ar-CH3), 3.41 and 3.51
(79%) as a beige powder. Mp 89–90 °C; IR NaCl:
m
(cmꢀ1) = 2985,
(t, 2H, respectively, H-200, H-500); 13C NMR (DMSO-d6);
d
2217, 1639, 1280; 1H NMR: (DMSO-d6); d (ppm) = 1.35 (m, 3H,
CH2–CH3), 2.24 (s, 3H, H-2), 4.32 (m, 2H, CH2–CH3), 7.15-7.48 (m,
10H, ar); 13C NMR (DMSO-d6); d (ppm) = 13.7 (CH2–CH3), 17.3 (C-
2), 63.0 (CH2–CH3), 105.3 (C-30), 115.2 (CN), 128.1–136.1 (14C, ar),
160.8 (C-20), 166.2 (C-1); MS m/z (rel int. %) = 346 (84) [M+], 276
(100). Anal. Calcd for C21H18N2OS: C, 72.80; H, 5.24; N, 8.09; S,
9.25. Found: C, 72.99; H, 5.03; N, 8.22; S, 9.32.
(ppm) = 8.5 (C-40-CH3), 10.7 (C-50–CH3), 17.7 (C-2), 24.1 and 25.2
(C-300, C-400), 47.3 (C-200, C-500), 79.5 (C-30), 113.5 (C-40), 116.3
(CN), 139.3 (C-50), 159.1 (C-1), 162.7 (C-20); MS m/z (rel int.
%) = 231 (100) [M+], 216 (11), 203 (22), 188 (89), 161 (17). Anal.
Calcd for C13H17N3O: C, 67.51; H, 7.41; N, 18.17. Found: C, 67.52;
H, 7.38; N, 18.12.
4.1.2.36. 4,5-Diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-
3-furonitrile (25e). A solution of ethyl N-(3-cyano-4,5-diphenyl-
2-furyl)ethanimidoate (23e) (0.79 mmol, 0.26 g) in pyrrolidine
(5 mL) was refluxed for 5 h. Excess pyrrolidine was removed in va-
cuo and the residue purified by crystallization from ethanol to
yield 0.19 g (69%) as pale yellow crystals. Mp 173–174 °C; IR NaCl:
4.1.2.32. Methyl N-(3-cyano-4,5-dimethyl-2-furyl)ethanimido-
ate (23b). Preparation was according to the general procedure B,
this compound was obtained from 2-amino-4,5-dimethyl-3-furo-
nitrile (19b) (5.0 mmol, 0.68 g) after 5 h. The solvents were
removed in vacuo and the residue purified by flash chromatogra-
phy on silica gel by using a gradient from 100% cyclohexane to
cyclohexane/ethyl acetate = 85:15 as eluent to yield 0.49 g (51%)
m
(cmꢀ1) = 2873, 2210, 1558; 1H NMR: (DMSO-d6); d (ppm) = 1.93
(m, 4H, H-30, H-40), 2.33 (s, 3H, H-2), 3.56 (m, 4H, H-20, H-50),
7.18–7.52 (m, 10H, ar); 13C NMR (DMSO-d6); d (ppm) = 18.4 (C-
2), 24.1 and 24.5 (C-3 and C-4 of pyrrolidine), 47.6 and 47.8 (C-2
and C-5 of pyrrolidine), 99.4 (C-30), 115.7 (CN), 121.9 (C-40),
124.7 (C-2000, C-6000), 127.3 (C-400), 128.3 (C-4000), 128.6 (C-3000, C-
5000), 128.9 (C-200, C-300, C-400, C-500), 129.5 (C-1000), 131.2 (C-100),
139.9 (C-50), 160.0 (C-10), 163.3 (C-20); MS m/z (rel int. %) = 355
(100) [M+], 250 (38). Anal. Calcd for C23H21N3O: C, 77.72; H, 5.96;
N, 11.82. Found: C, 77.34; H, 6.24; N, 11.90.
as a beige powder. Mp 55–56 °C; IR NaCl:
m
(cmꢀ1) = 2950, 2221,
1
1654, 1288; H NMR: (DMSO-d6); d (ppm) = 1.97 (m, 3H, 50-CH3),
2.18 (m, 9H, 40-CH3 and N(CH3)2), 3.81 (s, 3H, O–CH3); 13C NMR
(DMSO-d6); d (ppm) = 9.0 (CH3 at C-40), 11.3 (CH3 at C-50), 19.4
(C-2), 55.0 (OCH3), 85.3 (C-30), 114.8 (CN), 115.0 (C-40), 143.3 (C-
50), 158.8 (C-1), 168.3 (C-20); MS m/z (rel int. %) = 192 (100) [M+],
149 (41). Anal. Calcd for C10H12N2O2: C, 62.49; H, 6.29; N, 14.57.
Found: C, 62.60; H, 6.38; N, 14.35.
4.1.2.33. Ethyl N-(3-cyano-4,5-diphenyl-2-furyl)ethanimidoate
(23e). 2-Amino-4,5-dimethyl-3-furonitrile (19e) (1,45 mmol,
0.38 g) was refluxed in 1,1,1-triethoxyethane (5 mL) for 3 h. Excess
orthoester was distilled off and the residue purified by flash chro-
matography on silica gel by using a gradient from 100% cyclohex-
ane to cyclohexane/ethyl acetate = 85:15 as eluent to yield 0.39 g
4.1.2.37. N2,N2 -Dimethyl-5,6,7,8-tetrahydro[1]benzothieno[2,3-
b]pyridine-2,4-diamine (26a). This compound was synthesized
according to the general procedure A from N0-(3-cyano-4,5,6,7-tet-
rahydro-1-benzothien-2-yl)-N,N-dimethylethanimidamide (20a)
(6.0 mmol, 0.74 g) refluxing for 8 h. The product was purified by
flash chromatography on silica gel by using a gradient from 100%
cyclohexane to cyclohexane/ethyl acetate = 85:15 as eluent to
(81%) as a beige powder. Mp 81–83 °C; IR NaCl:
m
(cmꢀ1) = 2985,
2225, 1643, 1292; 1H NMR: (DMSO-d6); d (ppm) = 1.33 (t, 3H,
J = 7.3 Hz, CH2–CH3), 2.36 (s, 3H, H-2), 4.33 (q, 2H, J = 7.3 Hz,
yield 80 mg (11%) as a beige powder. Mp 177–179 °C; IR NaCl: m
(cmꢀ1) = 3494, 2927, 2854, 1589, 1565; 1H NMR: (DMSO-d6); d
(ppm) = 1.77 (m, 4H, H-6, H-7), 2.62 (m, 2H, H-5), 2.87 (m, 2H,
H-8), 2.94 (N(CH3)2), 5.58 (s, 2H, NH2, exchangeable with D2O),
5.77 (s, 1H, H-3); 13C NMR (DMSO-d6); d (ppm) = 22.3, 22.5 (C-6,
C-7), 24.8 (C-5), 25.7 (C-8), 37.8 (N(CH3)2), 86.9 (C-3), 112.3 (C-
4a), 124.3 (C-4b), 126.9 (C-8a), 151.1 (C-4), 157.9 (C-2), 160.4 (C-
9a); MS m/z (rel int. %) = 247 (100) [M+], 232 (88), 218 (74), 204
CH2–CH3), 7.27–7.54 (m, 10H, ar); 13C NMR (DMSO-d6);
d
(ppm) = 13.7 (CH2–CH3), 19.4 (C-2), 63.6 (CH2–CH3), 86.4 (C-30),
113.8 (C-40), 121.9 (CN), 125.3–135.5 (12C, ar), 142.9 (C-50), 168.5
(C-1), 170.2 (C-20); MS m/z (rel int. %) = 330 (77) [M+], 288 (17),
260 (100). Anal. Calcd for C21H18N2O2: C, 76.34; H, 5.49; N, 8.48.
Found: C, 76.20; H, 5.68; N, 8.23.

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4417
(48). Anal. Calcd for C13H17N3S: C, 63.12; H, 6.93; N, 16.99; S, 12.96.
Found: C, 62.89; H, 6.93; N, 17.02; S, 12.90.
300 (37). Anal. Calcd for C21H19N3O: C, 76.57; H, 5.81; N, 12.76.
Found: C, 76.70; H, 5.79; N, 12.91.
4.1.2.38. N6,N6,3-Trimethyl-2-phenylthieno[2,3-b]pyridine-4,6-
diamine (26c). Preparation according to general procedure A
from N0-(3-cyano-4-methyl-5-phenyl-2-thienyl)-N,N-dimethyleth-
animidamide (20c) (0.75 mmol, 0.21 g) by refluxing for 5 h. The
residue was purified by crystallization from ethanol to yield
4.1.2.42. 2,3-Diphenyl-6-pyrrolidin-1-ylthieno[2,3-b]pyridin-4-
amine (28e). Preparation was according to the general procedure
A from 4,5-diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]thio-
phene-3-carbonitrile (24e) (0.36 mmol, 0.13 g) refluxing for 5 h.
The residue was purified by crystallization from ethanol to yield
0.14 g (65%) of beige crystals. Mp 181–183 °C (dec); IR NaCl:
m
70 mg (52%) as a beige powder. Mp 219–222 °C; IR NaCl:
m
d
(cmꢀ1) = 3505, 3390, 3197, 2915, 1581; 1H NMR: (DMSO-d6);
d (ppm) = 2.49 (s, 3H, CH3 at C-5), 2.98 (s, 6H, N(CH3)2), 5.80 (s,
2H, NH2, exchangeable with D2O), 5.87 (s, 1H, H-3), 7.31–7.49
(m, 5H, ar); 13C NMR (DMSO-d6); d (ppm) = 15.4 (CH3), 37.7
(N(CH3)2), 87.1 (C-3), 99.5 (C-4a), 114.0 (C-5), 125.6 (C-40), 127.0
(C-6), 128.6 (C-30, C-50), 129.4 (C-20, C-60), 134.3 (C-10), 152.1
(C-4), 158.2 (C-2), 161.0 (C-7a); MS m/z (rel int. %) = 283 (100)
[M+], 268 (57), 254 (51), 240. Anal. Calcd for C16H17N3S: C, 67.81;
H, 6.05; N, 14.38; S, 11.31. Found: C, 67.94; H, 5.90; N, 14.18; S,
11.19.
(cmꢀ1) = 3426, 3052, 2923, 2854, 1590;
1
H NMR: (DMSO-d );
6
(ppm) = 1.95 (m, 4H, H-30, H-40), 3.39 (m, 4H, H-20, H-50), 4.88 (s,
2H, NH2, exchangeable with D2O), 5.61 (s, 1H, H-3), 7.09-7.53,
13
(m, 10H, ar); C NMR (DMSO-d6); d (ppm) = 24.9 (C-30, C-40),
46.4 (C-20, C-50), 86.9 (C-3), 112.6 (C-4a), 126.7–130.8 (12C, ar),
134.0 und 136.7 (C-100 and C-1000), 150.6 (C-4), 156.2 (C-2), 160.7
(C-7a); MS m/z (rel int. %) = 371 (100) [M+], 342 (88), 302 (47).
Anal. Calcd for C23H21N3S: C, 74.36; H, 5.70; N, 11.31; S, 8.63.
Found: C, 74.49; H, 5.64; N, 11.42; S, 8.49.
4.1.2.43. 2,3-Dimethyl-6-pyrrolidin-1-ylfuro[2,3-b]pyridin-4-
amine (29b). Preparation was according to general procedure
A from 4,5-dimethyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-3-
furonitrile (25b) (0.75 mmol, 0.17 g) refluxing for 5 h. The resi-
due was purified by flash chromatography on silica gel using a
gradient from 100% cyclohexane to cyclohexane/ethyl acetate/
methanol = 5:4:1 as eluent to yield 98 mg (57%) as a beige pow-
4.1.2.39. N6,N6-Dimethyl-2,3-diphenylthieno[2,3-b]pyridine-
4,6-diamine (26e). Preparation was according to general proce-
dure
A
from N0-(3-cyano-4,5-diphenyl-2-thienyl)-N,N-dimethy-
lethanimidamide (20e) (1.0 mmol, 0.35 g) by refluxing for 5 h.
The residue was purified by recrystallization from ethanol to yield
0.33 g (96%) of a beige-brown powder. Mp 175–177 °C (dec); IR
NaCl:
m
(cmꢀ1) = 3324, 3205, 2923, 2854, 1585; 1H NMR: (DMSO-
der. Mp 250–255 °C (dec); IR NaCl: m
(cmꢀ1) = 3347, 2969, 2919,
d6); d (ppm) = 3.00 (s, 3H, N(CH3)2), 4.88 (s, 2H, NH2, exchangeable
with D2O), 5.77 (s, 1H, H-3), 7.07–7.50 (m, 10H, ar); 13C NMR
(DMSO-d6); d (ppm) = 37.7 (N(CH3)2), 86.52 (C-3), 112.6 (C-4a),
126.8 (C-400), 127.3 (C-6), 128.1 (C-4000), 128.2 (C-3000, C-5000), 128.5
(C-300, C-500), 128.7 (C-2000, C-6000), 130.0 (C-200, C-600), 130.7 (C-5),
134.0 (C-100), 136.6 (C-1000), 150.9 (C-4), 158.3 (C-2), 130.5 (C-7a);
MS m/z (rel int. %) = 345 (100) [M+], 330 (55), 316 (45), 302 (23).
Anal. Calcd for C21H19N3S: C, 73.01; H, 5.54; N, 12.16; S, 9.28.
Found: C, 72.82; H, 5.46; N, 12.28; S, 9.42.
2846, 1627, 1604; 1H NMR: (DMSO-d6); d (ppm) = 1.91 (m, 4H, H-
30, H-40), 2.18 and 2.19 (s, 3H, respectively, CH3), 3.23-3.32 (m,
4H, H-20, H-50), 5.47 (s, 1H, H-3), 5.60 (s, 2H, NH2, exchangeable
with D2O); 13C NMR (DMSO-d6); d (ppm) = 9.8 and 10.8 (CH3),
24.9 (C-30, C-40), 46.4 (C-20, C-50), 85.6 (C-3), 97.9 (C-4a), 108.3
(C-5), 140.8 (C-4), 150.3 (C-6), 154.9 (C-2), 162.0 (C-7a); MS m/
z (rel int. %) = 231 (100) [M+], 203 (65), 202 (69), 162 (62). Anal.
Calcd for C13H17N3O: C, 67.51; H, 7.41; N, 18.17. Found: C, 67.40;
H, 7.30; N, 17.90.
4.1.2.40. N6,N6,2,3-Tetramethylfuro[2,3-b]pyridine-4,6-diamine
(27b). Preparation was according to the general procedure A from
N0-(3-cyano-4,5-dimethyl-2-furyl)-N,N-dimethylethanimidamide
(21b) (0.7 mmol, 0.14 g) refluxing for 5 h. The residue was purified
by flash chromatography on silica gel by using a gradient from
100% cyclohexane to cyclohexane/ethyl acetate = 5:5 as eluent to
4.1.2.44. 2,3-Diphenyl-6-pyrrolidin-1-ylfuro[2,3-b]pyridin-4-
amine (29e). Preparation was according to the general proce-
dure A from 4,5-diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-
3-furonitrile (25e) (0.37 mmol, 0.13 g) refluxing for 5 h. The
residue was purified by crystallization from ethanol to yield
0.11 g (85%) as a beige powder. Mp 132–133 °C; IR NaCl:
m
yield 25 mg (17%) of a beige powder. Mp 210–212 °C; IR NaCl:
m
(cmꢀ1) = 3480, 3056, 2925, 2854, 1604; 1H NMR: (DMSO-d6); d
(ppm) = 1.96 (m, 4H, H-30, H-40), 3.38 (m, 4H, H-20, H-50), 4.99 (s,
2H, NH2, exchangeable with D2O), 5.55 (s, 1H, H-3), 7.15–7.61
(cmꢀ1) = 3502, 3355, 2960, 2919, 2854, 2803, 1608; 1H NMR:
(DMSO-d6); d (ppm) = 2.16 and 2.17 (s, 3H, respectively, ar-CH3),
2.90 (s, 6H, N(CH3)2), 5.62 (s, 1H, H-3), 5.63 (s, 2H, NH2, exchange-
able with D2O); 13C NMR (DMSO-d6); d (ppm) = 9.8 (C-3–CH3), 10.8
(C-2–CH3), 38.0 (N(CH3)2), 85.3 (C-5), 98.1 (C-3a), 108.2 (C-3),
141.2 (C-4), 150.5 (C-2), 157.1 (C-6), 161.8 (C-7a); MS m/z (rel
int. %) = 205 (100) [M+], 190 (74), 176 (56), 162 (34). Anal. Calcd
for C11H15N3O: C, 64.37; H, 7.37; N, 20.47. Found: C, 64.56; H,
7.36; N, 20.34.
13
(m, 10H, ar); C NMR (DMSO-d6); d (ppm) = 24.9 (C-30, C-40),
46.5 (C-20, C-50), 85.7 (C-3), 98.2 (C-4a), 117.0 (C-5), 124.5-129.5
(10C, ar), 130.5 and 133.4 (C-100, C-1000), 141.3 (C-4), 150.1 (C-6),
155.9 (C-2), 161.7 (C-7a); MS m/z (rel int. %) = 355 (100) [M+],
327(45), 312 (10), 286 (28), 257 (9). Anal. Calcd for C23H21N3O:
C, 77.72; H, 5.96; N, 11.82. Found: C, 77.85; H, 5.86; N, 11.72.
4.1.2.45. 2-Amino-6-methyl-5-phenylnicotinonitrile
4.1.2.41. N6,N6-Dimethyl-2,3-diphenylfuro[2,3-b]pyridine-4,6-
diamine (27e). Preparation was according to general procedure A
from N0-(3-cyano-4,5-diphenyl-2-furyl)-N,N-dimethylethanimida-
mide (21e) (0.25 mmol, 82 mg) by refluxing for 5 h. The residue
was purified by crystallization from ethanol to yield 79 mg (96%)
(30d). Dry gaseous ammonia was bubbled through a solution of
ethyl 2-cyanoethanimidoate-hydrochloride (17.5 mmol, 2.60 g) in
ethanol (30 mL) for 15 min at 0 °C. The mixture was allowed to
reach rt. To resulting golden solution, 4-(dimethylamino)-3-phe-
nylbut-3-en-2-one (5.0 mmol, 0.95 g) was added and the mixture
refluxed for 5 h, evaporated to dryness and the residue treated
with water. The pH was adjusted to >9 if necessary. Thereafter,
the aqueous suspension was extracted with ethyl acetate. The or-
ganic layer was dried with Na2SO4, filtered and the solvents re-
moved in vacuo. The crude product purified by flash
chromatography on silica gel by using a gradient from 100% cyclo-
hexane to cyclohexane/ethyl acetate = 5:5 as eluent to yield 0.36 g
of beige crystals. Mp 154–156 °C; IR NaCl:
m
(cmꢀ1) = 3482, 3390,
3208, 2923, 1608; 1H NMR: (DMSO-d6); d (ppm) = 3.08 (s, 6H,
N(CH3)2), 5.02 (s, 2H, NH2, exchangeable with D2O), 5.73 (s,1H,
H-5), 7.12–7.61 (m, 10H, ar); 13C NMR (DMSO-d6); d (ppm) = 37.9
(N(CH3)2), 85.3 (C-5), 98.3 (C-3a), 116.8 (C-3), 124.7-130.4 (10C,
ar), 133.3 (C-100), 137.3 (C-10), 141.7 (C-2), 150.3 (C-4), 158.1 (C-
6), 161.5 (C-7a); MS m/z (rel int. %) = 329 (100) [M+], 314 (32),

4418
C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
(34%) as a beige powder. Mp 177–183 °C; IR NaCl:
m
(cmꢀ1) = 3409,
4.1.2.49. N2,N2,6-Trimethyl-7-phenyl-1,8-naphthyridine-2,4-
diamine (32c). Preparation according to general procedure A
from N0-(3-cyano-5-methyl-6-phenylpyridin-2-yl)-N,N-dimethy-
lethanimidamide (31c) (0.75 mmol, 0.21 g) by refluxing for 10 h.
The residue was purified by crystallization from ethyl acetate to
yield 0.20 g (95%) as a beige powder. Mp 245–249 °C (dec); IR
2213, 1658; 1H NMR: (DMSO-d6); d (ppm) = 2.31 (s, 3H, CH3), 6.87
(s, 2H, NH2, exchangeable with D2O), 7.33–7.51 (m, 5H, ar), 7.69 (s,
1H, H-4); 13C NMR (DMSO-d6); d (ppm) = 23.4 (CH3), 86.7 (C-3),
117.0 (CN), 125.1 (C-5), 127.0 (C-40), 128.3 (C-20, C-60), 129.0 (C-
30, C-50), 138.2 (C-10), 142.3 (C-4), 158.4 (C-6), 159.7 (C-2); MS m/
z (rel int. %) = 209 (100) [M+]. Anal. Calcd for C13H11N3: C, 74.62;
H, 5.30; N, 20.08. Found: C, 74.50; H, 5.43; N, 19.88.
NaCl:
m
(cmꢀ1) = 3332, 2921, 2848, 1606; 1H NMR: (DMSO-d6); d
(ppm) = 2.32 (s, 3H, CH3), 3.08 (s, 6H, N(CH3)2), 6.06 (s, 1H, H-3),
6.45 (s, 2H, NH2, exchangeable with D2O), 7.40–7.58 (m, 5H, ar),
8.22 (s, 1H, H-5); 13C NMR (DMSO-d6); d (ppm) = 19.5 (ar-CH3),
37.7 (N(CH3)2), 87.2 (C-3), 108.1 (C-4a), 121.5 (C-6), 128.1 (C-40),
128.2 (C-30, C-50), 128.9 (C-20, C-60), 132.6 (C-5), 140.9 (C-1),
151.9 (C-4), 155.5 (C-8a), 160.1 (C-7), 160.2 (C-2); MS m/z (rel
int. %) = 278 (44) [M+], 263 (50), 249 (34), 235 (31), 207 (100). Anal.
Calcd for C17H18N4: C, 73.35; H ,6.52; N, 20.13. Found: C, 73.21; H,
6.39; N, 19.91.
4.1.2.46. N0-(3-Cyano-5-methyl-6-phenylpyridin-2-yl)-N,N-dime-
thylethanimidamide (31c). Preparation was according to the gen-
eral procedure B from 2-amino-5-methyl-6-phenylnicotinonitrile
(30c) (1.5 mmol, 0.31 g) after 3 h. The solvents were removed in va-
cuo and the residue purified by flash chromatography on silica gel by
using a gradient from 100% cyclohexane to cyclohexane/ethyl ace-
tate = 8:2 as eluent to yield 0.30 g (72%) as a beige wax-like solid.
Mp 96–97 °C; IR NaCl:
m
(cmꢀ1) = 2927, 2217, 1569; 1H NMR:
(DMSO-d6); d (ppm) = 2.11 (s, 3H, H-1), 2.24 (s, 3H, CH3 at C-50),
3.07 (s, 6H, (CH3)2N), 7.40–7.56 (m, 5H, ar), 7.98 (s, 1H, H-40); 13C
NMR (DMSO-d6); d (ppm) = 16.4 (C-2), 19.0 (CH3 at C-50), 37.9 and
38.4 (N(CH3)2), 100.2 (C-30), 118.3 (CN), 122.8 (C-50), 128.4 (C-200,
C-600), 128.8 (C-400), 129.2 (C-300, C-500), 140.0 (C-100), 144.4 (C-40),
160.4 (C-60), 161.3 (C-1), 161.8 (C-20); MS m/z (rel int. %) = 278 (85)
[M+], 264 (39), 252 (20), 234 (23), 208 (100), 193 (50). Anal. Calcd
for C17H18N4: C, 73.35; H, 6.52; N, 20.13. Found: C, 73.48; H, 6.50;
N, 19.92.
4.1.2.50. N2,N2,7-Trimethyl-6-phenyl-1,8-naphthyridine-2,4-
diamine (32d). Preparation according to general procedure A
from N0-(3-cyano-6-methyl-5-phenylpyridin-2-yl)-N,N-dimethy-
lethanimidamide (31d) (0.5 mmol, 0.14 g) refluxing for 5 h. The
residue was purified by crystallization from ethanol/ethyl acetate
to yield 78 mg (56%) as a beige powder. Mp 270–272 °C (dec); IR
NaCl:
m
(cmꢀ1) = 3351, 2954, 2923, 2854, 1635, 1608; 1H NMR:
(DMSO-d6); d (ppm) = 2.46 (s, 3H, ar-CH3), 3.11 (s, 6H, N(CH3)2),
6.05 (s, 1H, H-3), 6.47 (s, 2H, NH2, exchangeable with D2O), 7.36–
7.54 (m, 5H, ar), 8.17 (s, 1H, H-5); 13C NMR (DMSO-d6); d
(ppm) = 23.8 (ar-CH3), 37.4 (N(CH3)2), 86.8 (C-3), 107.1 (C-4a),
126.8 (C-5), 128.2–131.5 (6C, ar), 140.6 (C-4, C-10), 152.4 (C-8a),
157.2 (C-2), 160.4 (C-7); MS m/z (rel int. %) = 278 (67) [M+], 263
(100), 249 (52), 235 (51). Anal. Calcd for C17H18N4: C, 73.35; H,
6.52; N, 20.13. Found: C, 73.19; H, 6.33; N, 19.96.
4.1.2.47. N0-(3-Cyano-6-methyl-5-phenylpyridin-2-yl)-N,N-dime-
thylethanimidamide (31d). Preparation was according to the
general procedure B from 2-amino-6-methyl-5-phenylnicotinonit-
rile (30d) (3.34 mmol, 0.70 g). The solvents were removed in vacuo
and the product purified by flash chromatography on silica gel
using a gradient from 100% cyclohexane to cyclohexane/ethyl ace-
tate = 3:1 as eluent to yield 0.58 g (62%) as a beige powder. Mp
4.1.2.51. N2,N2-Dimethyl-6,7-diphenyl-1,8-naphthyridine-2,4-
diamine (32e). Preparation was according to general procedure A
from N0-(3-cyano-5,6-diphenylpyridin-2-yl)-N,N-dimethylethani-
midamide (31e) (0.6 mmol, 0.20 g) by refluxing for 5 h. The residue
was purified by flash chromatography on silica gel by using a gra-
dient from 100% cyclohexane to cyclohexane/ethyl acetate = 8:2 as
eluent followed by recrystallization from ethyl acetate to yield
126–128 °C; IR NaCl:
m
(cmꢀ1) = 2951, 2927, 2894, 2217, 1580,
1565; 1H NMR: (DMSO-d6); d (ppm) = 2.17 (s, 3H, H-2), 2.38 (s,
3H, ar-CH3), 3.12 (s, 6H, N(CH3)2), 7.37–7.55 (m, 5H, ar), 7.85 (s,
1H, H-40); 13C NMR (DMSO-d6); d (ppm) = 15.9 (C-2), 23.7 (ar-
CH3), 38.0 and 38.6 (N(CH3)2), 98.6 (C-30), 117.7 (CN), 127.3 (C-
400), 128.2 (C-50), 128.5 (2C; C-200, C-600), 129.0 (2C; C-300, C-500),
138.1 (C-40), 142.0 (C-100), 158.7 (C-20), 161.0 (C-1), 161.9 (C-60);
MS m/z (rel int. %) = 278 (100) [M+], 234 (25), 222 (32), 208 (64),
193 (46), 166 (33), 71 (47). Anal. Calcd for C17H18N4: C, 73.35; H,
6.52; N, 20.13. Found: C, 73.19; H, 6.43; N, 19.96.
0.18 g (88%) as a yellow powder. Mp 257–259 °C; IR NaCl:
m
d
(cmꢀ1) = 3340, 3212, 2923, 1608; 1H NMR: (DMSO-d6);
(ppm) = 3.13 (s, 6H, N(CH3)2), 6.11 (s, 1H, H-3), 6.58 (s, 2H, NH2,
exchangeable with D2O), 7.10–7.37 (m, 10H, ar), 8.38 (s, 1H, H-
5); 13C NMR (DMSO-d6); d (ppm) = 37.5 (N(CH3)2), 87.4 (C-3),
108.0 (C-4a), 126.4 (C-5), 127.5 (C-20, C-60, C-200, C-600), 128.0 (C-
400), 128.8 (C-40), 129.6 and 129.7 (C-30, C-50, C-300, C-500), 133.2
(C-100), 140.2 (C-6), 140.7 (C-10), 152.4 (C-4), 156.1 (C-7), 158.3
(C-8a), 160.8 (C-2); MS m/z (rel int. %) = 340 (97) [M+], 325 (100),
311 (77), 297 (49), 296 (36). Anal. Calcd for C22H20N4: C, 77.62;
H, 5.92; N, 16.46. Found: C, 77.44; H, 5.77; N, 16.24.
4.1.2.48. N0-(3-Cyano-5,6-diphenylpyridin-2-yl)-N,N-dimethyleth-
animidamide (31e). Alternative 1: 2-Amino-5,6-diphenylnicotino-
nitrile (30e) (0,75 mmol, 204 mg) was refluxed in 1,1-dimethoxy-
N,N-dimethylethanamine (DMA-DMA, 2.0 mL) for 2 h. The solvents
were removed in vacuo and the crude product purified by flash chro-
matography on silica gel by using a gradient from 100% cyclohexane
to cyclohexane/ethyl acetate = 8:2 as eluent to yield 93 mg (36%) as a
beige powder. Alternative 2: 2-Amino-5,6-diphenylnicotinonitrile
(30e) (1.5 mmol, 0.41 g) was treated according to general method
B. The solvents were removed in vacuo and the crude product puri-
fied by flash chromatography on silica gel by using a gradient from
100% cyclohexane to cyclohexane/ethyl acetate = 8:2 as eluent to
4.1.2.52. 5,6-Diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]-
nicotinonitrile (33e). 1-Acetylpyrrolidine (6.0 mmol, 0.68 g) was
solved in chloroform (4 mL) and phosphorus oxychloride (0.2 mL)
was added. The mixture was stirred for additional 6 min at rt.
Thereafter,
a solution of 2-amino-5,6-diphenylnicotinonitrile
yield 0.32 g (63%) as a beige powder. Mp 139–142 °C; IR NaCl:
m
(30e) (1.0 mmol, 0.27 g) in chloroform (3 mL) was added and the
whole mixture refluxed for 5 h. After cooling down to rt, the solu-
tion was poured into ice water and the chloroform removed in va-
cuo. The aqueous phase was treated with 2 M NaOH to adjust the
pH >9 before extraction with ethyl acetate. The organic layer was
dried with Na2SO4, and the solvent removed in vacuo. The residue
was purified by flash chromatography on silica gel by using a gra-
dient from 100% cyclohexane to cyclohexane/ethyl acetate = 4:1 as
eluent to yield 60 mg (16%) as a beige powder. Mp 160–163 °C; IR
(cmꢀ1) = 2931, 2221, 1604, 1562; 1H NMR: (DMSO-d6); d (ppm) =
2.22 (s, 3H, H-2), 3.12 (s, 6H, N(CH3)2), 7.12–7.44 (m, 10H, ar), 8.05
(s, 1H, H-40); 13C NMR (DMSO-d6); d (ppm) = 16.2 (C-2), 37.5 und
38.0 (N(CH3)2), 99.9 (C-30), 117.6 (CN), 127.0–139.4 (13C, C-50 and
ar), 143.8 (C-40), 158.4 (C-20), 161.1 (C-1), 161.8 (C-60); MS m/z (rel
int. %) = 340 (100) [M+], 326 (21), 312 (31), 296 (13), 284 (21), 270
(75), 255 (50), 227 (27). Anal. Calcd for C22H20N4: C, 77.62; H, 5.92;
N, 16.46. Found: C, 77.44; H, 5.79; N, 16.24.

C. Willemann et al. / Bioorg. Med. Chem. 17 (2009) 4406–4419
4419
NaCl:
m
(cmꢀ1) = 2969, 2950, 2931, 2873, 2217, 1608; 1H NMR:
been described in detail elsewhere.27 All compounds were dissolved
in DMSO (cell culture grade) to give stock solutions of 20 mM and
stored at ꢀ20 °C until used. On the day of testing, the stock solutions
were thawed and serially diluted in DMSO to the desired working
concentration range (i.e., 20, 10, 5.0, 2.50, 1.25 and 0.67 mM).
Depending on the expected potency, five working solutions were
selected and diluted 1000-fold into cell culture medium to treat
the cells. Control cells received just DMSO. The actively dividing cells
were exposed to test substances for a total of 96 h before fixing with
glutaraldehyde and staining with crystal violet. After washing out
the non-bound dye, the cell-bound dye was redissolved in 70% eth-
anol/water and the optical density (OD) of the wells at k = 570 nm
was measured with a plate reader. IC50 values (concentration caus-
ing 50% growth inhibition) were estimated by means of linear
regression analysis of the log dose–response curves.
(DMSO-d6); d (ppm) = 1.84–1.94 (m, 4H, H-300, H-400), 2.26 (s, 3H,
H-2), 3.50–3.60 (m, 4H, H-200, H-500), 7.12–7.36 (m, 10H, ar), 8.03
(s, 1H, H-40); 13C NMR (DMSO-d6); d (ppm) = 17.2 (C-2), 24.0 and
25.3 (C-300 und C-400), 47.0 and 47.3 (C-200, C-500), 99.9 (C-30),
117.6 (CN), 126.9-131.2 (11C, ar), 138.3 (C-40), 139.4 (C-10000),
143.7 (C-1000), 158.3 (C-20), 159.6 (C-1), 161.6 (C-60); MS m/z (rel
int. %) = 366 (85) [M+], 308 (27), 256 (100), 255 (54), 227 (26), 84
(50), 70 (37), 68 (48). Anal. Calcd for C24H22N4: C, 78.66; H, 6.05;
N, 15.29. Found: C, 78.80; H, 5.89; N, 15.36.
4.1.2.53. 6,7-Diphenyl-2-pyrrolidin-1-yl-1,8-naphthyridin-4-
amine (34e). Preparation was according to the general procedure
A from 5,6-diphenyl-2-[(1-pyrrolidin-1-ylethylidene)amino]nico-
tinonitrile (33e) (0.12 mmol, 44 mg) by refluxing for 5 h. The
residue was purified by flash chromatography on silica gel by using
a gradient from cyclohexane/ethyl acetate = 8:2 to cyclohexane/
ethyl acetate/methanol = 5:4:1 as eluent to yield 35 mg (80%) as
Acknowledgement
beige-brown crystals. Mp 240–245 °C (dec); IR NaCl:
m
(cmꢀ1) = 3332, 2950, 2927, 2854, 1631, 1604; 1H NMR: (DMSO-
d6); d (ppm) = 1.99 (m, 4H, H-30, H-40), 3.35-3.55 (m, 4H, H-20, H-
50), 5.95 (s, 1H, H-3), 6.61 (s, 2H, NH2, exchangeable with D2O),
7.04–7.49 (m, 10H, ar), 8.40 (s, 1H, H-5); MS m/z (rel int. %) = 366
(70) [M+], 338 (100), 311 (24), 297 (41). Anal. Calcd for C24H22N4:
C, 78.66; H, 6.05; N, 15.29. Found: C, 78.54; H, 6.22; N, 15.07.
We thank Dr. Rainer Waibel, Department Chemie und Pharma-
zie, Lehrstuhl Pharmazeutische Chemie, Universität Erlangen, for
NMR data and helpful discussions.
References and notes
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Med. Chem. 1994, 2, 781; (b) Jones, R. A.; Pastor, J.; Siro, J.; Voro, T. N.
Tetrahedron 1996, 53, 479; (c) Zhang, Q.; Shi, C.; Zhang, H.-R.; Wang, K. K. J. Org.
Chem. 2000, 65, 7977; (d) Chabane, H.; Lamazzi, C.; Thiery, V.; Guillaument, G.;
Besson, T. Tetrahedron Lett. 2002, 43, 2483; (e) Tran-Thi, H. A.; Nguyen-Thi, T.;
Michel, S.; Tillequin, F.; Koch, M.; Pfeifer, B.; Pierre, A.; Trinh-Van-Dufat, H.
Chem. Pharm. Bull. 2004, 52, 540; (f) Moody, D. L.; Dyba, M.; Kosakowska-
Cholody, T.; Tarasova, N. I.; Michejda, C. J. Bioorg. Med. Chem. Lett. 2007, 2380.
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1979, 1706.
6. Dotzauer, B.; Grünert, R.; Bednarski, P. J.; Lanig, H.; Landwehr, J.; Troschütz, R.
Bioorg. Med. Chem. 2006, 14, 7282.
7. Dotzauer, B.; Troschütz, R. Synlett 2004, 1039.
8. Arnould, J.-C.; Bird, T. G.; Boyle, F. T.; Blakey, D. C. WO 01/92224, 2001.
9. Campbell, S. F.; Hardstone, J. D.; Palmer, M. Tetrahedron Lett. 1984, 25, 4813.
10. Eiden, F.; Berndl, K. Arch. Pharm. (Weinheim) 1986, 317, 347.
11. Roy, S.; Eastman, A.; Gribble, G. Tetrahedron 2006, 62, 7838.
12. Ottoni, O.; Cruz, R.; Alves, R. Tetrahedron 1998, 54, 13915.
13. Kikugawa, Y. Synthesis 1981, 460.
4.1.2.54. N0-(2-Cyano-1-naphthyl)-N,N-dimethylethanimida-
mide (36). Preparation was according to the general procedure
B from 1-amino-2-naphthonitrile (35) (6.0 mmol, 1.01 g) by
refluxing for 5 h. The solvents were removed in vacuo and the res-
idue purified by flash chromatography on silica gel by using a gra-
dient from 100% cyclohexane to cyclohexane/ethyl acetate/
methanol = 5:4:1 as eluent to yield 0.68 g (48%) as a beige oil. IR
NaCl:
m
(cmꢀ1) = 2931, 2888,2213, 1608; 1H NMR: (DMSO-d6); d
(ppm) = 1.81 (s, 3H, H-2), 3.13 (s, 6H, N(CH3)2), 4.48–4.67 (m,
4H, ar) 7.88–7.95 (m, 2H, ar); MS m/z (rel int. %) = 237 (100)
[M+], 193 (97), 181 (84), 168 (17), 152 (63). Anal. Calcd for
C15H15N3: C, 75.92; H, 6.37; N, 17.71. Found: C, 76.11; H, 6.42;
N, 17.59.
4.1.2.55. N2,N2-Dimethylbenzo[h]quinoline-2,4-diamine (37).
Preparation was according to the general procedure A from
N0-(2-cyano-1-naphthyl)-N,N-dimethylethanimidamide (36) (1.5
mmol, 0.36 g) refluxing for 5 h. The residue was purified by flash
chromatography on silica gel by using a gradient from 100% cyclo-
hexane to cyclohexane/ethyl acetate = 3:1 as eluent to yield 0.29 g
14. Kikugawa, Y.; Miyake, Y. Synthesis 1981, 461.
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(82%) as a beige powder. Mp 146–148 °C; IR NaCl:
m
(cmꢀ1) = 3386,
2927, 2857, 1631, 1596; 1H NMR: (DMSO-d6); d (ppm) = 3.15 (s,
6H, N(CH)2), 6.15 (s, 1H, H-3), 6.33 (s, 2H, NH2, exchangeable with
D2O), 7.40 (m, 1H, H-6), 7.54 (m, 2H, H-8 and H-9), 7.79–7.92 (m,
2H, H-7 und H-10), 9.00 (m, 1H, H-5); 13C NMR (DMSO-d6); d
(ppm) = 37.4 (N(CH3)2), 87.7 (C-3), 109.4 (C-4a), 119.0 (C-10a),
120.1 (C-10), 124.5 (C-9), 124.9 (C-7), 126.8 (C-6), 127.1 (C-8),
130.3 (C-6a), 133.6 (C-5), 145.6 (C-10b), 152.4 (C-4), 158.1 (C-2);
MS m/z (rel int. %) = 237 (100) [M+], 222 (91), 208 (66), 194 (57) ,
166 (55). Anal. Calcd for C15H15N3: C, 75.92; H, 6.37; N, 17.71. Found:
C, 76.07; H, 6.44; N, 17.66.
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4.2. Cell proliferation assay
ˇ
30. Aimová, D.; Svobodová, L.; Kotrbová, V.; Mrazová, B.; Hodek, P.; Hudecek, J.;
All cell lines were obtained from the German Collection of Micro-
organisms and Cell Culture (DSMZ) in Braunschweig, Germany.
Detailsof thecytotoxictestingand calculationof theIC50 valueshave
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