Synthesis and ring closure reactions of pyrido[3,2,1-jk]carbazol-6-ones[1]

Article abstract of DOI:10.1002/jhet.5570420112

4-Hydroxy-5-phenylpyrido[32,1-jk]carbazol-6-ones (4, 5), which were obtained from carbazoles 1 and malonates 2 or 3, were converted to reactive intermediates such as 4-chlorides 9 or 4-tosylates 10, which gave in turn 4-azido-5-phenyl derivatives 11.5-Alkyl-4-azides 11 were not obtained in this manner; however a new one-pot azidation reaction was developed starting from 4-hydroxy derivatives 4 which gave azides 11 in good yields. 4-Azido-5-phenyl derivative 11f cyclized on thermolysis to the indole 12. The thermal behaviour of the azides 11 was studied by thermoanalytical methods (DSC).

Full text of DOI:10.1002/jhet.5570420112

Jan-Feb 2005
85
Synthesis and Ring Closure Reactions of
Pyrido[3,2,1-jk]carbazol-6-ones[1]
Hoai V. Dang, Bernd Knobloch, Nargues S. Habib, Thomas Kappe
and Wolfgang Stadlbauer*
Department of Chemistry, Karl-Franzens University of Graz
Heinrichstrasse 28, A-8010 Graz, Austria/Europe
Received August 26, 2004
4-Hydroxy-5-phenylpyrido[3,2,1-jk]carbazol-6-ones (4, 5), which were obtained from carbazoles 1 and
malonates 2 or 3, were converted to reactive intermediates such as 4-chlorides 9 or 4-tosylates 10, which
gave in turn 4-azido-5-phenyl derivatives 11. 5-Alkyl-4-azides 11 were not obtained in this manner; however
a new one-pot azidation reaction was developed starting from 4-hydroxy derivatives 4 which gave azides 11
in good yields. 4-Azido-5-phenyl derivative 11f cyclized on thermolysis to the indole 12. The thermal
behaviour of the azides 11 was studied by thermoanalytical methods (DSC).
J. Heterocyclic Chem., 42, 85 (2005).
Pyrido[3,2,1-jk]carbazol-6-one is part of the hetero-
without interruption when a 1:1 mixture of the malonate
and the carbazole 1a was heated for 12 hours in refluxing
diphenyl ether solution which limits the thermolysis tem-
perature to 253 °C. The yields are within 60-80% compa-
rable to the stepwise reaction; the workup however is eas-
ier and the purity of the products is better.
The more reactive hydroxycarbazoles 1b reacted already
in refluxing malonate 2 (190-280 °C depending on the sub-
stituent R1 of 2) in a 1:2 mixture in similar yields in 1 hour
to the 3,4-dihydroxypyrido[3,2,1-jk]carbazol-6-ones 5.
The electron rich hydroxy substituted carbazole part was
the favored cyclization partner and no formation of iso-
mers was observed. At these short reaction times and com-
parable low reaction temperatures we expected a further
cyclic skeleton of many natural products (e.g., strychnos
alkaloids such as strychninolones and brucinolones [2],
picrasidin Q [3] and olivacine alkaloids [4]). It possesses
the biologically interesting combination of indole and
2-pyridone structures. Moreover, some derivatives have
found interest in pharmacological [5] or in dye chemistry
[6]. Our interest is focused to 4-hydroxy-5-substituted
pyrido[3,2,1-jk]carbazol-6-ones (4, 5) which possess 2
reactive positions: the hydroxy group at C-4, which can be
substituted by various nucleophiles, and the CH-acidic
proton at C-5, which reacts with a large number of elec-
trophiles. In this contribution we want to report an
improved synthesis of 4-hydroxy-5-substituted pyrido-
[3,2,1-jk]carbazol-6-ones, the acetylation, tosylation and
the nucleophilic exchange of the hydroxy groups.
Scheme 1
The synthesis of some 4-hydroxy-5-substituted
pyrido[3,2,1-jk]carbazol-6-ones 4 is described in the litera-
ture in a few cases either by thermal condensation of mal-
onates 2 with carbazole 1a at about 300 °C with moderate
yields [7], or by thermal condensation of dichlorophenyl-
malonates with carbazole 1 at 260 °C with good yields [8].
We adopted the cyclocondensation methods of malonates
with 1,3-dinucleophiles earlier described for quinolones
and related compounds [9] for the synthesis of 4-hydroxy-
5-substituted pyrido[3,2,1-jk]carbazol-6-ones 4 and 5.
The first reaction step leads in a condensation reaction at
about 200 °C to the monoanilides of the carbazole 1a with
the malonates 2; the end of this reaction step can be easily
observed by the end of ethanol evolution; further thermol-
ysis at higher temperatures (300-350 °C) gives, by elimi-
nation of the second equivalent of ethanol, an intermediate
α-oxo ketene which attacks in an electrophilic reaction the
ortho-position of the aromatic ring to cyclize to the
pyrido[3,2,1-jk]carbazol-6-ones 4. The yields of this reac-
tion type are within 60-90% except with the octadecyl
malonate 2j; in this case only 24% of 4j was obtained. It
was also possible to carry out this reaction in one step

86
H. V. Dang, B. Knobloch, N. S. Habib, T. Kappe and W. Stadlbauer
Vol. 42
reaction: as shown in similar systems such as 2-naphthols
[10,11], the kinetically controlled reaction should lead in a
first step via the hydroxycarbazole ester to an indolo-
coumarin, which on thermal rearrangement should give
the thermodynamically stable pyrido[3,2,1-jk]carbazol-6-
ones 5. However, we could not find in any case coumarin
derivatives neither as the major product nor as byproduct.
Also attempts with highly reactive malonates such as bis-
(2,4,6-trichlorophenyl)benzylmalonate 3e [12], which
cyclized in 15 minutes at 210 °C with 2-hydroxycarbazole
(1b) afforded pyrido[3,2,1-jk]carbazol-6-ones 5; no trace
of a coumarin derivative could be detected.
Pyrido[3,2,1-jk]carbazolones 4 and 5 can exist in 2 tau-
tomeric structures A and B. Both spectroscopic data and
chemical reactivity confirm that the hydroxy structure A is
favored: nmr spectra of 4 and 5 do not show an aliphatic
proton of B at C-5, but the 4-hydroxy signal of 4 at 10.8-
11.0 ppm; ir spectra reveal only amide carbonyl signals
between 1640 and 1660 cm-1. The dioxo tautomers of type
B exist only in fixed derivatives such as 5-alkyl-5-
arylpyrido[3,2,1-jk]carbazol-4,6-diones [13]. The hydroxy
form is obviously present when rather stable sodium salts
of 4 are formed: already in the synthesis of 4a and 4e we
found, that during work-up with sodium hydroxide solu-
tion an insoluble sodium salt 6a and 6e as byproduct was
produced, which could be purified and recrystallized.
Acetylation of hydroxy derivatives 4a,f with refluxing
acetic anhydride formed in 2-6 hours 4-acetyoxypyrido-
[3,2,1-jk]carbazolones 7. The acetylation of dihydroxy
derivative 5a afforded in one hour reaction time only the
monoacetoxy product 8. Comparison of nmr signals
showed, that the acetylation of 5a has taken place at the 3-
and not at the 4-hydroxy group, probably by kinetically
controlled reaction which favors the 3-hydroxy group
because of higher reactivity or lack of hydrogen bonds.
Nucleophilic displacement of the 4-hydroxy group of 4
by chlorine was easily achieved by reaction with phospho-
ryl chloride to give 4-chloropyrido[3,2,1-jk]carbazolones
9 in 50-80% yield; 3,4-dihydroxypyrido[3,2,1-jk]car-
bazoles 5 afforded only a mixture of compounds which
was not worked up. The nucleophilic exchange of 4-chloro
substituents in 9 against the azide group to form 4-azi-
dopyrido[3,2,1-jk]carbazolones 11 was only possible with
a 5-phenyl substituent in 9f. With 5-alkyl substituents,
only mixtures of the azido product, the chloro product and
decomposition products were obtained. For the synthesis
of these desired 5-alkyl-4-azidopyrido[3,2,1-jk]car-
bazolones 11, however, we developed a new one-pot syn-
thesis starting from 4-hydroxypyrido[3,2,1-jk]car-
bazolones 4, sodium azide and phosphoryl chloride in
dimethylformamide. The yield was only 20-50%, but the
Scheme 3
Scheme 2

Jan-Feb 2005
Synthesis and Ring Closure Reactions of Pyrido[3,2,1-jk]carbazol-6-ones
87
spectra were taken on a Galaxy Series FTIR 7000 in potassium
bromide pellets. Elemental analyses were performed on a Fisons
elemental analyzer Mod. EA 1108, and are within ±0.4 of the
theoretical percentages. Mass spectra were taken on a HP
LC/MSD mass spectral instrument (ESI or APCI: 50-200 eV,
nitrogen). All reactions were monitored by thin layer chromatog-
raphy, carried out on 0.2 mm silica gel 60 F-254 (Merck) plates
using uv light (254 and 366 nm) for detection.
Common reagent-grade chemicals are either commercially
available and were used without further purification or prepared
by standard literature procedures. Diethyl 2-hexylmalonate (2g)
was prepared from 1-bromohexane and diethyl malonate as
described in ref. [18]. Diethyl 2-cyclohexylmalonate (2h) was
prepared from 1-bromocyclohexane and diethyl malonate as
described in ref. [19]. Diethyl 2-heptylmalonate (2i) was prepared
from 1-bromoheptane and diethyl malonate as described in ref.
[20]. Diethyl 2-octadecylmalonate (2j) was prepared from 1-bro-
mooctadecane and diethyl malonate as described in ref. [21]. Bis-
(2,4,6-trichlorophenyl) benzylmalonate (3e) was prepared from
2,4,6-trichlorophenol and malonic acid as described in ref. [12].
purity of the products obtained with this method was
excellent. Another method for the introduction of azido
groups, which was performed successfully in many similar
cases (e.g., [14]), is the nucleophilic exchange of tosyloxy
substituents. In the pyrido[3,2,1-jk]carbazolone series,
however, again only the reactive 5-phenyl-4-tosyloxy
derivative 10f reacted to the azide 11f. The example reac-
tion of the 5-methyl derivative 10a gave again a mixture of
compounds containing 11a that was not further worked up.
Organic azides with reactive ortho-groups such as aryl-,
heteroaryl- or acyl groups are known to decompose on
thermolysis or photolysis followed by a cyclization to het-
erocycles, either via a nitrene or an electrocyclic mecha-
nism [15]. Mainly, this cyclization type leads to five-mem-
bered heterocycles. A typical example is the attack of the
azide nitrogen to the 2-position of a phenyl ring in ortho-
position to the azide forming indoles. We have studied a
large number of azido heterocycles as candidates for such
ring closure or decomposition reactions and we have found
that differential scanning calorimetry (DSC) is an excel-
lent tool both for the prediction of the reaction conditions
and furthermore for safety hints [11,16]. The DSC diagram
of the 4-azido-5-phenyl derivative 11f showed a single
well-shaped signal for the azide decomposition and
cyclization, with the typical high reaction enthalpy of -700
J/g [16]. The onset for the cyclization reaction was 165 °C,
which allowed us to chose - after consideraton of the typi-
cal downshift solvent effects for thermolysis [17] - reflux-
ing dimethylformamide as the solvent for decomposition.
In the preparative scale, 11f gave on cyclization in 60%
yield the highly fused indolo[2,3:4,5]pyrido[3,2,1-jk]car-
bazol-9-one 12, a hitherto unknown heterocyclic system.
In contrast to the well-shaped DSC diagram of 11f, the
DSC diagrams of 11a-e showed the typical follow-up
series of undefined decomposition maxima together with
rather low reaction enthalpies (between -20 and -50 J/g),
which made further experiments unnecessary.
General Procedure for the Preparation of 4-Hydroxypyrido-
[3,2,1-jk]carbazole-6-ones (4).
Method A.
A mixture of the appropriate alkyl- or arylmalonate 2 (0.12
mol) and carbazole (1a) (16.7 g, 0.10 mol) was heated to about
250 °C for 2 hours using distillation equipment. During this
period the first equivalent of ethanol (about 5 mL) was liberated.
Then the temperature was raised to about 330 °C for 30 min.
During this period the second equivalent of ethanol (about 4.5
mL) was liberated. After cooling to about 80-100 °C the residue
was triturated with methanol; the solid product was collected by
suction filtration, washed with cold methanol, dissolved in aque-
ous sodium hydroxide (0.25 M, 1000 mL) and insoluble products
were removed by filtration. The filtrate was extracted with
toluene (2x 250 mL) and cleared with charcoal (about 7 g). To
obtain the product the filtrate was acidified with conc. hydrochlo-
ric acid (50 mL); the solid was collected by filtration, washed
several times with water, recrystallized from the solvent listed
below and dried at 80-100 °C.
Method B.
A solution of the appropriate alkyl- or arylmalonate 2 (0.12
mol) and carbazole (1a) (16.7 g, 0.1 mol) in diphenylether was
heated under reflux for 12 hours. During this period ethanol
(about 9-10 mL) was liberated. Then the excess of diphenyl ether
was removed in vacuo, the residue was triturated with hexane and
the solid collected by suction filtration. The solid product was
dissolved in aqueous sodium hydroxide (0.25 M, 1000 mL); fur-
ther workup was accomplished as described in method A.
EXPERIMENTAL
Melting points were determined on a Gallenkamp Melting
Point Apparatus, Mod. MFB-595 in open capillary tubes.
Calorimetric data were obtained on a Rheometric Scientific
DSC-Plus instrument with the differential scanning calorimetry
software Orchestrator V6.2.2. The differential scanning
calorimetry plots were recorded between 25 and 400 °C, with a
heating rate of 2-10 °C/min, and 1.5-3 mg compound in sealed
aluminium crucibles (11 bar). The 1H nmr spectra were recorded
on a Bruker AMX 360 instrument (360 MHz) or on a Bruker
Avance DRX instrument (500 MHz). The 13C nmr-spectra were
recorded on a Bruker AM 360 instrument (90 MHz). Chemical
shifts are reported in ppm from internal tetramethylsilane stan-
dard and are given in δ-units. The solvent for NMR spectra was
deuteriodimethyl sulfoxide unless otherwise stated. Evaluation of
the spectra was performed using the software Mestrec 3. Infrared
4-Hydroxy-5-methylpyrido[3,2,1-jk]carbazol-6-one (4a).
This compound was obtained from diethyl methylmalonate
(2a) (20.9 g, 0.12 mol) using method B; the yield was 19.66 g
(79 %) pale yellow powder, mp 276 °C (ethanol); ir: 3500-2900
-1 1
m, 1650 s, 1626 s, 1562 s cm ; H nmr: δ 2.20 (s, CH ), 7.52
3
and 7.63 (2 t, J = 7.4 Hz, 2-H, 9-H, 10-H), 8.14, 8.29 and 8.36
(3 d, J = 7.6 Hz, 1-H, 3-H, 11-H), 8.61 (d, J = 8.4 Hz, 8-H),
10.91 (s, OH).
Anal. Calcd. for C
H NO : C, 77.10; H, 4.45; N, 5.62.
16 11
Found: C, 77.36; H, 4.39; N, 5.51.
2

88
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Vol. 42
5-Ethyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4b).
5-Cyclohexyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4h).
This compound was obtained from diethyl ethylmalonate (2b)
(22.5 g, 0.12 mol) using method A; the yield was 15.2 g (58 %)
colorless prisms, mp 257 °C (toluene), lit. mp. 257-258 °C [7];
ir: 3450-3000 m, b, 1640 m, 1620 s, 1595 s, 1575 m cm-1.
This compound was obtained from diethyl cyclohexyl-
malonate (2h) (29.0 g, 0.12 mol) using method A; the yield was
21.5 g (68%) colorless prisms, mp 218.3 °C (acetic acid); ir:
3500-3100 b, 2920 m, 2850 w, 1640 sh, 1620 s, 1600 m cm-1; 1H
nmr: δ 1.10-1.90 (m, 5 CH2), 2.25 (t, J = 7 Hz, CH), 7.40-7.70 (m,
2-H, 9-H, 10-H), 8.20-8.40 (m, 1-H, 3-H, 11-H), 8.61 (d, J = 7
Hz, 8-H).
4-Hydroxy-5-propylpyrido[3,2,1-jk]carbazol-6-one (4c).
This compound was obtained from diethyl propylmalonate
(2c) (24.2 g, 0.12 mol) using method B; the yield was 20.56 g
(74%) colorless prisms, mp 247.5 °C (acetic acid); ir: 3350-3100
Anal. Calcd. for C21H19NO2: C, 79.47; H, 6.03; N, 4.41.
Found: 79.09; H, 5.68; N, 4.07.
1
b, 2960 w, 2840 w, 1640 sh, 1630s, 1595 m, 1575 m cm-1; H
nmr: δ 0.96 (t, J = 7 Hz, CH3), 1.54 (q, J = 7 Hz, CH2), 2.67 (t, J =
7 Hz, Ar-CH2), 7.48 and 7.58 (2 t, J = 7 Hz, H-2, H-9, H-10),
8.10, 8.24 and 8.31 (3 d, J = 7 Hz, 1-H, 3-H, 11-H), 8.57 (d, J = 7
Hz, 8-H), 10.80 (s, br, OH).
Anal. Calcd. for C18H15NO2: C, 77.96; H, 5.45; N, 5.05.
Found: C, 77.60; H, 5.38; N, 5.02.
5-Heptyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4i).
This compound was obtained from diethyl heptylmalonate (2i)
(31.0 g, 0.12 mol); using method A, the yield was 18.0 g (57 %);
using method B, the yield was 21.9 g (66%) pale yellow prisms,
mp 167-171 °C; ir: 3400-3100 b, 2920 s, 2850 s, 1645 m, 1620 s,
1595 s, 1580 s cm-1; 1H nmr: δ 0.85 (t, J = 7 Hz, CH3), 1.20-1.75
(m, 5 CH2), 2.71 (t, J =7 Hz, Ar-CH2), 7.42-7.75 (m, 2-H, 9-H, 10-
H), 8.10-8.42 (m, 1-H, 3-H, 11-H), 8.62 (dd, J = 2 and 7 Hz, 8-H).
Anal. Calcd. for C22H23NO2: C, 79.25; H, 6.95; N, 4.20.
Found: C, 79.61; H, 6.58; N, 4.02.
5-Butyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4d).
This compound was obtained from diethyl butylmalonate (2d)
(25.9 g, 0.12 mol); using method A, the yield was 22.4 g (77 %);
using method B, the yield was 17.5 g (59%); pale yellow powder,
mp 242-243 °C (acetic acid); ir: 3350-3040 m, 2960-2840 w,
1640 m, 1630 w, 1620 s, 1595 s, 1575 m cm-1; 1H nmr: δ 0.91 (t,
J = 7 Hz, CH3), 1.33-1.41 (m, CH2), 1.48-1.52 (m, CH2), 2.69 (t,
J = 7 Hz, Ar-CH2), 7.46 and 7.57 (2 t, J = 7 Hz, 2-H, 9-H, 10-H),
8.05, 8.27 and 8.33 (3 d, J = 7 Hz, 1-H, 3-H, 11-H), 8.52 (d, J = 7
Hz, 8-H), 10.80 (s, br, OH).
4-Hydroxy-5-octadecylpyrido[3,2,1-jk]carbazol-6-one (4j).
This compound was obtained from diethyl octadecylmalonate
(2j) (49.6 g, 0.12 mol) using method A; the yield was 11.6 g
(24%) pale yellow powder, mp 231 °C (acetic acid); ir: 3400-
3100 b, 2920 s, 2850 s, 1645 m, 1620 s, 1595 s, 1580 s cm-1.
Anal. Calcd. for C33H45NO2: C, 81.27; H, 9.30; N, 2.87.
Found: C, 80.94; H, 9.67; N, 2.88.
Anal. Calcd. for C19H17NO2: C, 78.33; H, 5.88; N, 4.81.
Found: C, 78.19; H, 5.93; N, 4.71.
5-Benzyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4e).
General Procedure for the Preparation of 3,4-Dihydroxypyrido-
[3,2,1-jk]carbazol-6-ones (5).
This compound was obtained from diethyl benzylmalonate
(2e) (30.0 g, 0.12 mol); using method A, the yield was 25.3 g (78
%); using method B, the yield was 26.9 g (83%) colorless prisms,
mp 252 °C; lit. mp 247-248 °C [8]; ir: 3500-2900 m, 1640 s cm-1;
1H nmr: δ 4.05 (s, CH2), 7.14 (t, J = 7.0 Hz, 4-H of benzyl), 7.24
(t, J = 7.6 Hz, 3-H and 5-H of benzyl), 7.35 (d, J= 7.0 Hz, 2-H and
6-H of benzyl), 7.50, 7.60 and 7.63 (3 t, J = 7.5 Hz, 2-H, 9-H, 10-
H), 8.18, 8.28 and 8.38 (3 d, J = 7.7 Hz, 1-H, 3-H,11-H), 8.57 (d,
J = 8.3 Hz, 8-H).
A mixture of 2-hydroxycarbazole (1b) (1.82 g, 10 mmol) and
the appropriate substituted malonate 2 (20 mmol) was heated
for 1 hour under reflux (about 250-300 °C) using distillation
equipment. The 2-hydroxycarbazole first dissolved and then a
white precipitate separated and 2 equivalents of ethanol (about
9-10 mL) were liberated. The reaction mixture was cooled to
room temperature and then quenched with a mixture of
diethylether/hexane (1:4). The obtained precipitate was col-
lected by filtration, washed with hexane and recrystallized from
the solvent listed below.
4-Hydroxy-5-phenylpyrido[3,2,1-jk]carbazol-6-one (4f).
This compound was obtained from diethyl phenylmalonate
(2f) (28.3 g, 0.12 mol); using method A, the yield was 28.0 g (90
%); using method B, the yield was 23.3 g (75%) pale yellow
prisms, mp 215-216 °C (ethanol), lit. mp 207-210 °C [7,8]; ir:
3220-3000 m, 1650 s, 1625 m, 1610 s, 1594 s, 1575 s cm-1; 1H
nmr (CDCl3): δ 7.46-7.61 (m, 2-H, 9-H, 10-H of carbazole, 2
PhH), 8.03, 8.09 and 8.18 (3 d, J = 7.7 Hz, 1-H, 3-H, 11-H), 8.71
(d, J = 8.1 Hz, 8-H), 11.00 (s, OH).
3,4-Dihydroxy-5-methylpyrido[3,2,1-jk]carbazol-6-one (5a).
This compound was obtained from diethyl methylmalonate
(2a) (3.4 g, 20 mmol); the yield was 2.49 g (94%), colorless nee-
dles, mp 274 °C (dimethylformamide); ir: 3380-2700 w, 1655 s,
1620 s, 1600 s, 1580 s cm-1; 1H nmr: δ 2.60 (s, CH3), 6.98 (d, J =
7 Hz, H-2), 7.42 and 7.47 (2 t, J = 7 Hz, 9-H, 10-H), 8.03 and 8.09
(2 d, J = 7 Hz, 1-H, 11-H), 8.54 (d, J = 8 Hz, 8-H).
5-Hexyl-4-hydroxypyrido[3,2,1-jk]carbazol-6-one (4g).
Anal. Calcd. for C16H11NO3: C, 72.45; H, 4.18; N, 5.28.
Found: C, 72.83; H, 4.26; N, 5.33.
This compound was obtained from diethyl hexylmalonate (2g)
(29.3 g, 0.12 mol) using method A; the yield was 21.0 g (66%),
pale yellow prisms, mp 167-171 °C (acetic acid); ir: 3400-3100 b,
2960-2880 w, 1640 m, 1620 s, 1595 s cm-1; 1H nmr: δ 0.85 (t, J =
7 Hz, CH3) 1.25-1.65 (m, 4 CH2), 2.60 (t, J = 7 Hz, Ar-CH2),
7.36-7.70 (m, 2-H, 9-H, 10-H), 8.15-8.35 (m, 1-H, 3-H, 11-H),
8.60 (d, J = 7 Hz, 8-H), 11.00 (s, OH).
5-Ethyl-3,4-dihydroxypyrido[3,2,1-jk]carbazol-6-one (5b).
This compound was obtained from diethyl ethylmalonate (2b)
(3.9 g, 20 mmol); the yield was 2.34 g (84%) colorless prisms,
mp 290 °C (dimethylformamide/water); ir: 3400-2700 m, 1655 s,
1610 s, 1595 s cm-1; 1H nmr: δ 1.15 (t, J = 7 Hz, CH3), 2.60 (q, J
= 7 Hz, CH2), 6.95 (d, J = 7 Hz, 2-H), 7.30-7.69 (m, 9-H, 10-H),
7.95 and 8.05 (2 d, J = 8 Hz, 1-H, 11-H), 8.55 (d, J = 8 Hz, 8-H).
Anal. Calcd. for C
H
NO : C, 78.97; H, 6.63; N, 4.39.
21 21
Found: C, 79.06; H, 6.21; N, 4.33.
2

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Synthesis and Ring Closure Reactions of Pyrido[3,2,1-jk]carbazol-6-ones
89
Anal. Calcd. for C17H13NO3: C, 73.11; H; 4.69; N, 5.01.
Found: C, 73.01; H, 4.72; N, 4.97.
Sodium 5-Benzyl-6-oxo-6H-pyrido[3,2,1-jk]carbazol-4-olate
(6e).
A mixture of carbazole (1a) (1.67 g, 10 mmol) and diethyl ben-
zylmalonate (2a) (1.74 g, 10 mmol) was reacted and worked up
according to the procedure described for 4e (Method A). The
residue, which was insoluble in 0.25 M sodium hydroxide solu-
tion, was isolated by filtration, washed with cold water and dried.
The yield was 0.57 g (16%) colorless prisms, mp 245 °C from
toluene/ethanol; ir: 3500-2900 m, 1711 s, 1684 s, 1599 s cm-1; 1H
nmr: δ 4.05 (s, CH2), 7.14 (t, J = 7.0 Hz, 4-H of benzyl), 7.24 (t, J
= 7.6 Hz, 3-H and 5-H of benzyl), 7.35 (d, J = 7.0 Hz, 3-H and 6-
H of benzyl), 7.48, 7.59 and 7.63 (3 t, J = 7.5 Hz, 2-H, 9-H, 10-
H), 8.18, 8.26 and 8.36 (3 d, J = 7.7 Hz, 1-H, 3-H, 11-H), 8.55 (d,
J = 8.3 Hz, 8-H).
5-Butyl-3,4-dihydroxy-pyrido[3,2,1-jk]carbazol-6-one (5d).
This compound was obtained from diethyl butylmalonate (2d)
(4.4 g, 20 mmol); the yield was 2.52 g (82%), colorless needles,
mp 310 °C (dimethylformamide); ir: 3375 m, 3240-2800 m, 1655
s, 1625 sh, 1610 s, 1595 s cm-1; 1H nmr (CF3COOH): δ 1.05 (t, J
= 7 Hz, CH3), 1.40-1.80 (m, 2 CH2), 2.70-3.10 (m, Ar-CH2), 7.10
(d, J = 8 Hz, 2-H), 7.30-7.60 (m, 9-H, 10-H), 7.80 and 8.00 (2 d,
J = 8 Hz, 1-H and 11-H), 8.25 (d, J = 8 Hz, 8-H).
Anal. Calcd. for C19H17NO3: C, 74.25; H, 5.58; N, 4.56.
Found: C, 74.30; H, 5.67; N, 4.58.
5-Benzyl-3,4-dihydroxypyrido[3,2,1-jk]carbazol-6-one (5e).
Anal. Calcd. for C22H14NNaO2: C, 76.07; H, 4.06; N, 4.03.
Found: C, 75.74; N, 3.85; N, 3.67.
Method A: This compound was obtained from diethyl benzyl-
malonate (2e) (5.0 g, 20 mmol) using the general method for 5 in
1.8 g (53%) yield.
5-Methyl-6-oxo-6H-pyrido[3,2,1-jk]carbazol-4-yl Acetate (7a).
Method B: A mixture of 2-hydroxycarbazole (1b) (0.37 g, 2
mmol) and bis-(2,4,6-trichlorophenyl) benzylmalonate (3e) (1.1
g, 2 mmol) was heated for 15 min in an oil bath adjusted at 210
°C. Then the reaction mixture was cooled to room temperature
and treated several times with a mixture of diethylether/hexane
(1:4) until a solid was formed. The precipitate was collected by
filration and recrystallized from dimethylformamide/methanol.
The yield was 0.58 g (85%) as colorless plates, mp 280 °C
(dimethylformamide/methanol); ir: 3380-2600 m, 1655 m, 1625
sh, 1615 s, 1600 s cm-1; 1H nmr: δ 4.15 (s, CH2), 7.05 (d, J = 8 Hz,
2-H), 7.30-7.60 (m, 9-H, 10-H, 5 PhH of benzyl), 7.80 and 8.00
(2 d, J = 8 Hz, 1-H, 11-H), 8.12 (d, J = 7 Hz, 8-H).
A mixture of the 4-hydroxy-pyridocarbazolone 4a (1.30 g, 5
mmol), acetic anhydride (3.00 g, 29 mmol) and glacial acetic acid
(20 mL) was heated under reflux for 2 hours. Then the reaction
mixture was cooled to room temperature, poured into ice/water
(100 mL). The solid was collected by suction filtration and
washed with water. The yield was 1.20 g (68 %), yellow prisms,
mp 190 °C (from ethyl acetate/ethanol); ir: 1770 s, 1664 s, 1636
sh, 1602 m cm-1; 1H nmr (CDCl3): δ 2.23 (s, acetyl-CH3), 2.52 (s,
CH3), 7.45-7.60 (m, 2-H, 9-H, 10-H, 3-H), 8.04 and 8.08 (2 d, J =
7.6 Hz, 1-H, 11-H), 8.72 (d, J = 8.1 Hz, 8-H).
Anal. Calcd. for C18H13NO3: C, 74.22 H; 4.50; N, 4.81. Found:
C, 74.20 ; H, 4.48; N, 5.01
Anal. Calcd. for C22H15NO3: C, 77.41; H, 4.43; N, 4.10.
Found: C, 76.93; H, 4.67; N, 4.31.
6-Oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl Acetate (7f).
A mixture of the 4-hydroxy-pyridocarbazolone 4f (1.50 g, 4.6
mmol), acetic anhydride (3.00 g, 29 mmol) and glacial acetic acid
(20 mL) was heated under reflux for 6 hours followed by work-
up as described for 6a. The yield was 1.20 g (68 %), yellow
prisms, mp 207 °C (from ethyl acetate/ethanol); ir: 1773 s, 1666
s, 1639 s, 1608 s, 1574 s cm-1; 1H nmr (CDCl3): δ 2.17 (s, CH3),
7.43-7.46 (m, 5 PhH), 7.46 and 7.55 (2 t, J = 7.6 Hz, 2-H, 9-H,
10-H), 7.64, 8.06 and 8.15 (2 d, J = 7.5 Hz, 1-H, 3-H, 11-H), 8.71
(d, J= 8.1 Hz, 8-H).
3,4-Dihydroxy-5-phenylpyrido[3,2,1-jk]carbazol-6-one (5f).
This compound was obtained from diethyl phenylmalonate (2f)
(4.8 g, 20 mmol) using Method A; the yield was 2.4 g (86%), col-
orless prisms, mp 312 °C (DMF); ir: 3380-2700 m, 1655 m, 1620
sh, 1610 sh, 1600 s, 1570 s cm-1; 1H nmr: δ 7.38-7.44 (m, 2-H, 9-
H), 7.45-7.50 (m, 5 PhH), 7.55 (t, J = 8 Hz, 10-H), 7. 62 and 8.41
(2 d, J = 8 Hz, 1-H, 11-H), 8.58 (d, J = 8 Hz, 8-H), 8.99 (s, OH).
Anal. Calcd. for C21H13NO3: C, 77.06; H, 4.00; N, 4.28.
Found: C, 76.91; H, 4.16; N, 4.43.
Anal. Calcd. for C23H15 NO3: C, 78.18; H, 4.28; N, 3.96.
Found: C, 77.79; H, 4.16; N, 3.89.
Sodium 5-Methyl-6-oxo-6H-pyrido[3,2,1-jk]carbazol-4-olate
(6a).
4-Hydroxy-5-methyl-6-oxo-6H-pyrido[3,2,1-jk]carbazol-3-yl
Acetate (8).
A mixture of carbazole (1a) (8.35 g, 50 mmol) and diethyl
methylmalonate (2a) (8.70 g, 50 mmol) was heated to 270 °C for
2 hours; the liberated ethanol was removed via an air condenser.
The reaction mixture was cooled to 100 °C, then methanol was
added and the solid material was crushed, collected by suction
filtration, and dissolved in 1 M sodium hydroxide solution (200
mL). The alkaline solution was filtered by suction and the insolu-
ble residue was isolated, washed with a small amount of cold
water and dried. The yield was 9.83 g (79%), yellowish powder,
mp > 350 °C (sublimation) (dimethylformamide); ir: 3500-2900
m, 1612 s, 1571 s cm-1; 1H nmr: δ 1.90 (s, CH3), 7.35 and 7.48 (2
t, J = 7.4 Hz, 2-H, 9-H, 10-H), 7.85, 8.08 and 8.12 (3 d, J = 7.6
Hz, 1-H, 3-H, 11-H), 8.61 (d, J = 8.4 Hz, 8-H); MS: m/z (%) =
250 (M + 1 of 4a, 100%).
A solution of 3,4-dihydroxy-pyridocarbazolone 5a (0.53 g, 2
mmol) in acetic anhydride (0.5 mL, 5 mmol) and acetic acid (4.5
mL) was heated under reflux for 1 hour, cooled to room tempera-
ture and taken to dryness under reduced pressure. The yield was
0.68 g (90%) colorless prisms, mp 292 °C (glacial acetic acid); ir:
3340-3100 m, 1765 m, 1730 w, 1700 s, 1640 s, 1615 m, 1590 m
cm-1; 1H nmr (CF3COOH): δ 1.80 (s, acetyl-CH3), 2.60 (s, CH3),
6.70-7.60 (m, 2-H, 9-H, 10-H), 8.00-8.20 (m, 1-H, 11-H, 8-H).
Anal. Calcd. for C18H13NO4: C, 70.35; H, 4.26; N, 4.56.
Found: C, 69.96; H, 4.61; N, 4.19.
4-Chloro-5-methylpyrido[3,2,1-jk]carbazol-6-one (9a).
A mixture of 4-hydroxypyridocarbazolone 4a (2.49 g, 10
mmol) and phosphorylchloride (3.1 g, 20 mmol) was heated for 1
hour to 100 °C. The reaction mixture was cooled to room temper-
Anal. Calcd. for C16H10NNaO2: C, 70.85; H, 3.72; N, 5.16.
Found: C, 70.61; H, 3.63; N, 4.76.

90
H. V. Dang, B. Knobloch, N. S. Habib, T. Kappe and W. Stadlbauer
Vol. 42
ature and then poured into ice/water (100 mL). The mixture was
brought to pH 4-6 with 0.25 M sodium hydroxide solution; the
solid, collected by suction filtration, was washed with water and
dried. The yield was 2.00 g (75%), ash-grey powder, mp 162 °C
5-Methyl-6-oxo-6H-pyrido[3,2,1-jk]carbazol-4-yl Toluene-4-
sulfonate (10a).
A mixture of 4-hydroxypyridocarbazolone 4a (2.50 g, 10
mmol), p-toluenesulfonyl chloride (7.60 g, 20 mmol) and triethy-
lamine (2.00 g, 20 mmol) in dry acetonitrile (50 mL) was stirred
and heated under reflux for 18 hours. The reaction mixture was
cooled to room temperature and poured into ice/water (100 mL).
The obtained precipitate was collected by filtration, washed with
water and dried. The yield was 3.19 g (79%) colorless prisms, mp
240 °C from ethanol; ir: 2918 m, 1667 s, 1636 w, 1605m, 1600
sh, 1580 w cm-1; 1H nmr (CDCl3): δ 2.04 (s, CH3 of CH3), 2.52
(s, p-tosyl-CH3), 7.43-7.52 (m, 9-H, 10-H and 2 ArH of p-tosyl),
7.60 (t, J= 7.8 Hz, 2-H), 7.70 (d, J = 7.9 Hz, 1 ArH of p-tosyl),
7.92 (m, 11-H, 1 ArH of p-tosyl), 8.08 and 8.12 (2 d, J = 7.6 Hz,
1-H, 3-H), 8.72 (d, J = 8.2 Hz, 8-H).
1
from ethanol; ir: 3500-2900 m, 1664 s, 1602 s cm-1; H nmr
(CDCl3): δ 2.48 (s, CH3), 7.47, 7.52 and 7.58 (3 t, J = 7.5 Hz, 2-
H, 9-H, 10-H), 7.85, 8.00 and 8.04 (3 d, J = 7.4 Hz, 1-H, 3-H, 11-
H), 8.66 (d, J = 7.8 Hz, 8-H).
Anal. Calcd. for C16H10ClNO: C, 71.78; H, 3.77; N, 5.23.
Found: C, 71.88; H, 3.66; 5.08.
4-Chloro-5-ethylpyrido[3,2,1-jk]carbazol-6-one (9b).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4b (2.73 g, 10 mmol) according to the procedure
described for 9a; the yield was 2.30 g (82%) yellowish prisms, mp
130 °C from ethanol; ir: 3500-2900, 1657 s, 1603 s cm-1; 1H nmr
(CDCl3): δ 1.30 (t, J = 7.5 Hz, CH3), 3.04 (q, J = 7.3 Hz, CH2),
7.51, 7.58 and 7.62 (3 t, J = 7.6 Hz, 2-H, 9-H, 10-H), 7.96, 8.08 and
8.14 (2 d, J = 7.8 Hz, 1-H, 3-H, 11-H), 8.74 (d, J = 7.8 Hz, 8-H).
Anal. Calcd. for C17H12ClNO: C, 72.47; H, 4.29; N, 4.97.
Found: C, 72.30; H, 4.22; N, 4.87.
Anal. Calcd. for C23H17NO4S: C, 68.47; H, 4.25; N, 3.47.
Found: C, 68.36; H, 4.17; N, 3.48.
6-Oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl Toluene-4-
sulfonate (10f).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4f (3.10 g, 10 mmol) according to the method described
for 10a. The yield was 3.20 g (69%) colorless prisms, mp 198 °C
from ethanol; ir: 1669 s, 1603 s, 1569 s cm-1; 1H nmr (CDCl3): δ
2.42 (s, CH3), 7.08 (d, J = 8.1 Hz, 2 ArH of p-tosyl), 7.29-7.33
(m, 2 ArH of p-tosyl, 5 PhH), 7.53, 7.59 and 7.67 (3 t, J = 7.7 Hz,
2-H, 9-H, 10-H), 8.10, 8.18 and 8.21 (3 d, J = 7.8 Hz, 1-H, 3-H
11-H), 8.71 (d, J = 8.1 Hz, 8-H).
5-Butyl-4-chlorpyrido[3,2,1-jk]carbazol-6-one (9d).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4d (2.91 g, 10 mmol) according to the procedure
described for 9a; the yield was 1.57 g (51%) yellowish powder,
mp 194 °C; ir: 3400-2500, 1660 s, 1605 s cm-1.
Anal. Calcd. for C19H16ClNO: C, 73.66; H, 5.21; N, 4.52.
Found: C, 73.29; H, 5.13; N, 4.78.
Anal. Calcd. for C28H19NO4S: C, 72.24; H, 4.11; N, 3.01.
Found: C, 71.87; H, 4.05; N, 3.00.
5-Benzyl-4-chloropyrido[3,2,1-jk]carbazol-6-one (9e).
4-Azido-5-methylpyrido[3,2,1-jk]carbazol-6-one (11a).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4e (3.25 g, 10 mmol) according to the procedure
described for 9a; the yield was 2.00 g (58%) colorless prisms, mp
A mixture of 4-hydroxypyridocarbazolone 4a (3.0 g, 12 mmol)
and sodium azide (1.50 g , 23 mmol) in dimethylformamide (15
mL) was heated to 100 °C. At this temperature, phosphorylchlo-
ride (3.1 ml, 20 mmol) was added dropwise. The reaction mixture
was held at 100 °C for 1 hour, then cooled to room temperature
and poured into ice/water (100 mL). The precipitate was col-
lected by suction filtration and dried. The yield was 1.50 g (55%)
yellowish prisms, mp/dec 126 °C (methanol); calorimetric data
for the thermolysis: decomposition at 119.6 °C onset, 130.5 °C
maximum; mp at 146.8 °C onset, 152.8 °C maximum, ∆H = 2.4
J/g; decomposition at 154.7 °C onset, 162.2°C maximum, ∆H = -
48 J/g; ir: 3500-2900 m, 2116 m, 1663 s, 1646 s, 1622 s, 1592 s
cm-1; 1H nmr (CDCl3): δ 2.50 (s, CH3), 7.46, 7.48 and 7.62 (3 t, J
= 7.6 Hz, 2-H, 9-H, 10-H), 7.95, 8.08 and 8.13 (3 d, J = 7.7 Hz, 1-
H, 3-H, 11-H), 8.73 (d, J = 8.1 Hz, 8-H).
1
242 °C from ethanol; ir: 3500-2900 m, 1661 s, 1604 s cm-1; H
nmr (CDCl3): δ 4.37 (s, CH2), 7.21 (t, J = 7.0 Hz, 4-H of benzyl),
7.23 (t, J = 7.6 Hz, 3-H and 5-H of benzyl), 7.32 (d, J = 7.0 Hz, 2-
H and 6-H of benzyl), 7.50, 7.55 and 7.58 (3 t, J = 7.5 Hz, 2-H, 9-
H, 10-H), 7.97, 8.05 and 8.13 (3 d, J = 7.6 Hz, 1-H, 3-H, 11-H),
8.73 (d, J = 8.3 Hz, 8-H).
Anal. Calcd. for C22H14ClNO: C, 76.86; H, 4.10; N, 4.07.
Found: C, 77.11; H, 4.28; N, 3.81.
4-Chloro-5-phenylpyrido[3,2,1-jk]carbazol-6-one (9f).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4f (3.11 g, 10 mmol) according to the procedure
described for 9a; the yield was 2.20 g (67%) yellowish prisms,
mp 247 °C (ligroin or acetic acid); ir: 2300 – 3400, 1669 s, 1604
Anal. Calcd. for C16H10N4O: C, 70.07; H, 3.67; N, 20.43.
Found: C, 70.68; H, 3.93; N, 19.69.
1
s, 1554 s, 1439 s, 1337 s, 849 s, 756 s cm1; H nmr (CDCl3): δ
7.66-7.47 (m, 2-H, 9-H, 10-H, 5 PhH), 8.06, 8.11 and 8.22 (3 d, J
= 7.8 Hz, 1-H, 3-H, 11-H), 8.72 (d, J = 8.0 Hz, 8-H).
Anal. Calcd. for C21H12ClNO: C, 76.48; H, 3.67; N, 4.25.
Found: C, 76.29; H, 4.06; N, 4.07.
No correct analysis was obtained because of the ease of
decomposition of the azido compound.
4-Azido-5-ethylpyrido[3,2,1-jk]carbazol-6-one (11b).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4b (2.63 g, 10 mmol) according to the method described
for 11a; the yield was 1.80 g (52%), yellowish prisms, mp/dec 125
°C (methanol); calorimetric data for the thermolysis: mp at 125.4
°C onset, 128.3 °C maximum, ∆H = 20.5 J/g; decomposition at
148.5 °C onset, 150.6 °C maximum, ∆H = - 24 mcal/mg; ir: 3500-
2900 m, 2115 m, 1657 s, 1602 s cm-1; 1H nmr (CDCl3): δ 1.31 (t, J
= 7.2 Hz, CH3), 3.03 (q, J = 7.4 Hz, CH2), 7.46, 7.61 and 7.47 (3 t,
4-Chloro-5-hexylpyrido[3,2,1-jk]carbazol-6-one (9g).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4g (3.19 g, 10 mmol) according to the procedure
described for 9a; the yield was 2.66 g (79%) yellowish prisms,
mp 104-107 °C (toluene); ir: 3550-2950, 1660 s, 1600 s cm-1.
Anal. Calcd. for C21H20ClNO: C, 74.66; H, 5.97; N, 4.15.
Found: C, 74.27; H, 5.59; N, 4.25.

Jan-Feb 2005
Synthesis and Ring Closure Reactions of Pyrido[3,2,1-jk]carbazol-6-ones
91
J = 7.6 Hz, 2-H, 9-H, 10-H), 7.92, 8.04 and 8.09 (3 d, J = 7.6 Hz,
1-H, 3-H, 11-H), 8.71 (d, J = 7.9 Hz, 8-H).
Anal. Calcd. for C17H12N4O: C, 70.82; H, 4.20; N, 19.43.
Found: C, 71.35; H, 4.15; N, 18.55.
Hz, 2-H), 7.42 (t, J = 7.8 Hz, 5-H), 7.53 (t, J = 7.6 Hz, 6-H), 7.65
- 7.75 (m, 11-H, 12-H, 13-H), 8.30 - 8.40 (m, 1-H, 3-H, 4-H, 10-
H), 8.77 (d, J = 8.1 Hz, 7-H), 13.06 (s, 1 H, NH); MS: m/z (%) =
309 (M+1, 100).
No correct analysis was obtained because of the ease of
decomposition of the azido compound.
Anal. Calcd. for C21H12N2O: C, 81.80; H, 3.92; N, 9.09.
Found: C, 81.60; H, 3.62; N, 8.71.
4-Azido-5-butylpyrido[3,2,1-jk]carbazol-6-one (11d).
REFERENCES AND NOTES
This compound was obtained from 4-hydroxypyridocar-
bazolone 4d (2.89 g, 10 mmol) according to the method described
for 11a; the yield was 0.66 g (21%), brownish prisms, mp/dec 84
°C (methanol); ir: 3600-2800 m, 2110 m, 1660 s, 1605 s cm-1.
Anal. Calcd. for C19H16N4O: C, 72.14; H, 5.10; N, 17.71.
Found: C, 72.41; H, 5.48; N, 17.33.
[1] Organic Azides in Heterocyclic Synthesis, Part 33. Part 32:
W. Stadlbauer and G. Hojas, J. Heterocyclic Chem., 40, 753 (2003).
[2] "The Merck Index", Vol. 12, 9020 and 1476 (1996), S.
Budavari, ed., Merck & Co Inc., Rahway, N. J., USA; G. F. Smith in
"The Alkaloids", Vol. VIII, 591 (1965), R. H. F. Manske, ed.; V. Prelog,
S. Szpilfogel and J. Battegay, Helv. Chim. Acta, 30, 366 (1947).
[3] T. R. Kasturi, L. Mathew and J. A. Sattigeri, Ind. J. Chem.,
29B, 1004 (1990).
4-Azido-5-benzylpyrido[3,2,1-jk]carbazol-6-one (11e).
This compound was obtained from 4-hydroxypyridocar-
bazolone 4e (3.23 g, 10 mmol) according to the method described
for 11a; the yield was 1.70 g (49%) yellowish prisms, mp/dec 135
°C (methanol); calorimetric data for the thermolysis: decomposi-
tion at 134.4 °C onset, 137.2 °C maximum, ∆H = - 44 J/g; ir:
[4] T. Ohmoto and K. Koike, Chem. Pharm. Bull., 33, 4901
(1985).
[5] E. Ziegler, U. Rossmann, F. Litvan and H. Meier, Monatsh.
Chem., 93, 26 (1962); E. Ziegler, F. Litvan (Geigy Chemical Corp.), US
Patent, 3 052 678 (1959), Chem. Abstr., 58, 3437e (1963); Geigy
Chemical Corp., Brit. Patent, 912 289 (1960); Chem. Abstr. 59, 645
(1963); M. Harfenist and E. Magnien, J. Org. Chem., 28, 538 (1963).
[6] O. S. Wolfbeis, E. Ziegler, A. Knierzinger, H. Wipfler and I.
Trummer, Monatsh. Chem., 111, 93 (1980); U. Zirngibl (Sandoz Ltd.),
Ger. Offen. DE 2 142 334, 1972 03 02 (1972); DE 71-2 142 334 -
19710824 (1971); Chem. Abstr., 77, 36383 (1972).
3500-2900 m, 2143 m, 1657 s, 1606 s, 1573 s cm-1; H nmr
1
(CDCl3): δ 4.17 (s, CH2), 7.14 (t, J = 7.0 Hz, 4-H of benzyl), 7.22
(t, J = 7.6 Hz, 3-H and 5-H of benzyl), 7.38 (d, J = 7.0 Hz, 3-H
and 6-H of benzyl), 7.50, 7.60 and 7.63 (3 t, J = 7.5 Hz, 2-H, 9-H,
10-H), 8.18, 8.28 and 8.38 (d, J = 7.6 Hz, 1-H, 3-H, 11-H), 8.57
(d, J = 8.3 Hz, 8-H).
Anal. Calcd. for C22H14N4O: C, 75.42; H, 4.03; N, 15.99.
Found: C, 75.79; H, 4.41; N, 15.60.
[7] P. Baumgarten and M. Riedel, Ber. Dtsch. Chem. Ges., 75,
984 (1942).
[8] E. Ziegler, H. Junek and U. Rossmann, Monatsh. Chem., 92,
809 (1961).
[9] W. Stadlbauer, E.-S. Badawey, G. Hojas , P. Roschger and
Th. Kappe, Molecules, 6, 345 (2001).
4-Azido-5-phenylpyrido[3,2,1-jk]carbazol-6-one (11f).
Method A: A mixture of pyridocarbazolyl toluene-4-sulfonate
9f (4.65 g, 10 mmol) and sodium azide (1.50 g, 23 mmol) in
dimethylformamide (30 mL) was heated to 80 °C for 30 min with
intensive stirring. Then the mixture was cooled to room tempera-
ture and poured into ice/water (500 mL); the obtained precipitate
was collected by suction filtration and washed with water. The
yield was 2.30 g (68%) yellowish powder, mp/dec 170 °C
(methanol).
[10] Th. Kappe, Tetrahedron Lett., 5327 (1968).
[11] Th. Kappe and W. Stadlbauer, Molecules, 1, 255 (1996).
[12] Th. Kappe in "Encyclopedia of Reagents for Organic
Synthesis", Vol. 1, 577 (1995), L. A. Paquette, ed., John Wiley & Sons,
Chichester - New York - Brisbane - Toronto - Singapore.
[13] W. Stadlbauer and Th. Kappe, Monatsh. Chem., 115, 467
(1984).
Method B: A mixture of 4-chloropyridocarbazolone 10f (3.29 g,
10 mmol) and sodium azide (1.50 g, 23 mmol) in dimethylfor-
mamide (50 mL) was heated to 80 °C for 2 hours with intensive stir-
ring. Workup was performed as described in method A. The yield
was 2.78 g (83%) brownish powder, mp/dec 162-168 °C (methanol);
calorimetric data for the thermolysis: decomposition at 166.7 °C
onset, 173.7 °C maximum, ∆H = - 723 J/g; ir: 2109 s, 1664 s, 1604 s,
1569 s cm-1; 1H nmr (CDCl3): δ 7.29-7.50 (m, 5 PhH), 7.52, 7.55 and
7.59 (3 t, J = 7.7 Hz, 2-H, 9-H, 10-H), 7.98, 8.09 and 8.19 (3 d, J =
7.4 Hz, 1-H, 3-H, 11-H), 8.70 (d, J = 7.9 Hz, 8-H).
[14] A. E. Täubl, K. Langhans, Th. Kappe and W. Stadlbauer, J.
Heterocyclic Chem., 39, 1259 (2002).
[15] P. A. S. Smith, in "Azides and Nitrenes", E. F. V. Scriven,
ed., Academic Press, Orlando, Florida, 1984; E. F. V. Scriven, K.
Turnbull, Chem. Rev., 88, 297 (1988); B. Iddon, O. Meth-Cohn, E. F. V.
Scriven, H. Suschitzky and P. T. Gallagher, Angew. Chem., Int. Ed.
Engl., 12, 900 (1979); V. A. Bakulev, C. O. Kappe, A. Padwa, in
"Organic Synthesis: Theory and Applications", Vol. 3, 149 (1996), T.
Hudlicky, ed., JAI Press Inc., Greenwich/USA - London.
[16] W. Stadlbauer and G. Hojas, J. Biophys. Biochem. Methods,
53, 89 (2002).
[17] W. Stadlbauer and G. Hojas, Proceedings of ECSOC-5, The
Fifth International Electronic Conference on Synthetic Organic
Chemistry, 2001; C.O. Kappe, P. Merino, A. Marzinzik, H. Wennemers,
T. Wirth, J.-J. Vanden Eynde and S.-K. Lin, (Eds). CD-ROM edition,
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[18] C. Marmillon, J. Bompart, M. Calas, R. Escale and P. A.
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Anal. Calcd. for C21H12N4O: C, 74.99; H, 3.60; N, 16.66.
Found: C, 75.36; H, 3.89; N, 16.27.
14H-Indolo[2,3:4,5]pyrido[3,2,1-jk]carbazol-9-one (12).
A solution of 4-azido-5-phenylpyridocarbazolone 11f (1.7 g, 5
mmol) in dimethylformamide (15 mL) was heated under reflux
for 6 hours. The mixture was cooled to room temperature and
then poured onto ice/water (100 mL); the resulting precipitate
was collected by suction filtration and washed with water. The
yield was 0.90 g (58 %), yellowish prisms, mp > 300 °C
(dimethylformamide/methanol); ir: 3287 s, 3055 w, 1654 m,
1640s, 1597 w, 1582 w cm-1; 1H nmr (CDCl3): δ 7.35 (t, J = 7.3
[19] J. C Allen, J. Chem. Soc., 4468 (1962).
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[21] W. Ho, G. F. Tutwiler, S. C. Cottrell, D. J. Morgans, O.
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