Thermolytic ring closure reactions of 4-azido-3-phenylsulfanyl- and 4-azido-3-phenylsulfonyl-2-quinolones to 12H-quinolino-[3,4-b][1,4]benzothiazin-6(5H)-ones [1]

Article abstract of DOI:10.1002/jhet.5570390621

4-Hydroxy-3-phenylsulfanyl-2-quinolones 2 and 4-hydroxy-3-sulfonyl-2-quinolones 7, which are readily accessible from 4-hydroxy-2-quinolones 1 and diphenyldisulfide or thiophenol, can be converted to 4-azido-3-phenylsulfanyl-2-quinolones 10 or 4-azido-3-ph

Full text of DOI:10.1002/jhet.5570390621

Nov-Dec 2002
Thermolytic Ring Closure Reactions of 4-Azido-3-phenylsulfanyl-
and 4-Azido-3-phenylsulfonyl-2-quinolones to 12H-Quinolino-
[3,4-b][1,4]benzothiazin-6(5H)-ones [1]
1259
Anna E. Täubl, Klaus Langhans, Thomas Kappe and Wolfgang Stadlbauer*
Department of Chemistry, Organic Synthesis Group, Karl-Franzens University of Graz
Heinrichstrasse 28, A-8010 Graz, Austria/Europe
Received June 23, 2002
4-Hydroxy-3-phenylsulfanyl-2-quinolones 2 and 4-hydroxy-3-sulfonyl-2-quinolones 7, which are readily
accessible from 4-hydroxy-2-quinolones1 and diphenyldisulfide or thiophenol, can be converted to 4-azido-
3-phenylsulfanyl-2-quinolones 10 or 4-azido-3-phenylsulfonyl-2-quinolones 12 via 4-chloro-3-phenylsul-
fanyl-2-quinolones 5 or 4-chloro-3-phenylsulfonyl-2-quinolones 9, respectively. Thermolysis of the azides
10 and 12 results in a cyclization reaction to give quinolino[3,4-b][1,4]benzothiazinone 11 and quino-
lino[3,4-b][1,4]benzothiazinone dioxides 13, respectively. The conditions for thermolysis have been studied
by differential scanning calorimetry (DSC).
J. Heterocyclic Chem., 39, 1259(2002).
Organic azides with reactive ortho-groups such as aryl-,
molar amount and the 3-phenylsulfanyl-2-quinolones 2a-c
were obtained in good to excellent yields. There is also the
possibility to obtain the thioethers 2 from thiophenol and
3-chloro-4-hydroxyquinolones 4 in pyridine as basic sol-
vent in excellent yields, however this method needs two
more steps.
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 [2]. Mainly, this cyclization type leads to five-mem-
bered heterocycles. Two typical examples are the attack of
the azide nitrogen either to the 2-position of a phenyl ring
in ortho-position to the azide forming indoles [3], or by
attack of the azide nitrogen to e.g. the oxygen atom of a
carbonyl group inortho-position to the azide forming isox-
azoles [4]. Only in a few cases, the formation of six-mem-
bered heterocycles is reported [2], e.g. with a benzyl sub-
stituent in ortho-position of the azido group; in this way
we obtained from 4-azido-3-benzyl-2-quinolones in good
yields dibenzo[ b,h][1,6]naphthyridin-6-ones [5].
Similarly, the phenylsulfanyl group, Ph-S, or their oxi-
dized variants, the phenylsulfoxide group, Ph-SO, and the
Scheme 1
phenylsulfonyl group, Ph-SO , seemed to be good candi-
2
dates for such a thermal azide cyclization.
Recently a direct sulfenylation of 4-hydroxy-2-
quinolones by the action of diphenyl disulfide has been
developed in our group [6,7]. This reaction sequence was
used, in this contribution, in order to obtain 4-azido-2-
quinolones with phenylsulfanyl groups in 3-position as
suitable starting materials for the planned thermal cycliza-
tion of azides to six-membered heterocycles. The reaction
of 4-hydroxy-2-quinolones 1 with diphenyl disulfide was
carried out as described in references [6,7] under basic
conditions. During the reaction the thiophenolate anion
was formed, which was oxidized by oxygen back to
diphenyl disulfide. In contrast to the earlier described
method [7], we obtained better results when the air for oxi-
dation was not bubbled through the reaction mixture, but
compressed air was blown onto the mixture with a tube
ending above the surface of the reaction mixture. This was
because the inlet pipe often was clogged when air was bub-
bled through the mixture. In this way the amount of
employed diphenyl disulfide could be reduced to a half-
To obtain the desired azides, 4-hydroxy-3-phenylsulfanyl-
2-quinolones 2 were converted in the next step to reactive
intermediates. The reaction of 2a with phosphoryl chloride
gave in excellent yields 4-chloro-1-methyl-3-phenylsulfanyl-
2-quinolone (5). The oxidation of the thioethers 2a-c gave
depending on the conditions either in alkaline hydrogen per-
oxide solution the sulfoxides 6a-c or with peracetic acid the
sulfones 7a-c. The oxidation to the sulfoxides 6a-c needed
some care, because higher temperatures and longer reaction

1260
A. E. Täubl, K. Langhans, T. Kappe and W. Stadlbauer
Vol. 39
times caused partial oxidation to the sulfones 7 that gave a
mixture which was difficult to separate. Keeping the temper-
ature at 20 °C by slow addition of hydrogen peroxide mini-
mized by-products. The reaction of the sulfones 7a-c with
phosphoryl chloride using triethylamine to destroy hydrogen
bondings between the hydroxy and the sulfonyl group gave
in excellent yields 4-chloro-3-phenylsulfonyl-2-quinolones
9a-c. However, the sulfoxides 6 could not be converted to
4-chloroquinolones, because a large number of unseparable
byproducts were formed. So the tosylates 8a-c, another reac-
tive class of compounds, were synthesized by reaction of the
sulfones 6 with tosylchloride in a basic solvent.
phenylsulfanyl-2-quinolone (10) were obtained using dif-
ferential scanning calorimetry. The diagrams revealed that
the azidoquinolone 10 started to decompose without a
melting area at about 140 °C. The reaction enthalpy (-190
mcal/mg) is rather high [1] which needs safety precautions
for larger reaction scales. After the reaction peak no
decomposition signals were visible and at 325 °C a small
melting area could be observed which could be assigned to
the cyclized follow-up product. This observation gave
hints that the reaction product was stable at higher temper-
atures without decomposition.
The cyclization was performed in a preparative manner
using xylene as the solvent following hints from the DSC
diagram. After a reaction time of 10 minutes, a light brown
solid began to be precipitated, and after 30 minutes the
reaction was finished. The reaction product was the
expected 5-methyl-12H-quinolino[3,4-b][1,4]benzo-
thiazino-6(5H)-one (11) which could be confirmed by
spectra and analytical data. The spectral data are also in
agreement with literature data of this compound obtained
from 4-hydroxy-1-methyl-2-quinolone (1a) and 2-amino-
thiophenol under acidic conditions [8].
Scheme 3
The reaction of the 3-phenylsulfinyl-4-tosyloxyquin-
olones 8a-c with sodium azide gave no synthetic useable
results. At low temperatures no reaction could be
observed, and at elevated temperatures decomposition to a
mixture of compounds took place.
The exchange of the chloro group in 4-chloro-3-phenyl-
sulfonylquinolones 9a-c could be easily achieved already
at room temperature using a small excess of sodium azide
in N-methylpyrrolidone as the solvent to give 4-azido-3-
phenylsulfonyl-2-quinolones 12a-c in excellent yields.
The data from differential scanning calorimetry (DSC)
Nucleophilic substitution of the chloro atom in 4-chloro-
1-methyl-3-phenylsulfanyl-2-quinolone (5) with the azide
anion was performed by reaction with sodium azide in
dimethyl formamide at 60 °C in nearly quantitative yield.
Data about the thermal behavior of 4-azido-1-methyl-3-

Nov-Dec 2002
Thermolytic Ring Closure Reactions
1261
otherwise stated. Chemical shifts are reported in ppm from internal
tetramethylsilane standard and are given in d-units. Infrared spec-
tra were taken on a Perkin-Elmer 298 spectrophotometer or 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. All reac-
tions were monitored by thin layer chromatography carried out on
0.2 mm silica gel 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.
4-Hydroxy-2-quinolones (1a-c) were obtained from the corre-
sponding anilines and diethyl malonate in a three step reaction
according to an earlier reported procedure [9]. 3,3-Dichloro-1-
methyl-quinoline-2,4(1H,3H)-dione (3) and 3-chloro-4-hydroxy-
1-methyl-quinolin-2(1H)-one (4) were obtained using the meth-
ods described in reference [10].
showed only a single signal with onsets between 156-187
°C, without further decomposition and melting peaks. The
reaction enthalpies range between -127 and -160 mcal/mg,
which is similarly high as in the azide 10, and again with
larger scales some safety precaution should be considered.
Thermogravimetric analyses of 12b show the cleavage of
nitrogen (mass defect 7% or 28 g/mol) between 177-183 °C,
followed by a horizontal line until 250 °C which indicates a
stable area, and then again continuous decomposition.
The synthetic thermolysis of the azides 12b,c was per-
formed in refluxing 1,2-dichlorobenzene according to the
onset temperatures of 154-160 °C obtained from DSC data;
after 10 minutes the evolution of nitrogen gas had stopped
and the reaction mixture was worked up. The spectral and
microanalytical data were in agreement with the structures
of 5-phenyl-12H-quinolino[3,4-b][1,4]benzothiazin-6(5H)-
one 7,7-dioxide (13b) and 4,5,6,14-tetrahydro-
benzo[9,10]quinolizino[3,2-b][1,4]benzothiazin-8-one 9,9-
dioxide (13c), a hitherto unknown class of compounds.
General Procedure for the Synthesis of 4-Hydroxy-3-phenylsul-
fanylquinolin-2(1H)-ones 2a-c.
A solution of the corresponding 4-hydroxy-2-quinolone 1a-c
(50-60 mmol) in dimethylformamide (100 mL) was combined with
an excess of dry potassium carbonate (10 g) and diphenyldisulfide
(25-30 mmol). The mixture was heated to 100-130 °C and stirred
for 5 hours. During the reaction time a stream of compressed air
was blown onto the mixture, using a tube which ended above the
surface of the reaction mixture to avoid blocking of the inlet pipe,
to oxidize the formed waste thiophenol back to diphenyldisulfide.
The reaction mixture was cooled to room temperature and diluted
with water (500 mL) and excess diphenyldisulfide was filtered off.
The filtrate was acidified with 6 N hydrochloric acid to pH = 1
(attention: strong foaming) and the resulting precipitate was sepa-
rated. To avoid bad smell from thiophenol residues, the filtrate was
oxidized using sodium hypochlorite solution.
4-Hydroxy-1-methyl-3-phenylsulfanylquinolin-2(1H)-one (2a).
Method a.
Compound 2a was obtained according to the general proce-
dure from 4-hydroxy-2-quinolone 1a (10.51 g, 60 mmol) and
diphenyldisulfide (6.55 g, 30 mmol); the yield was 15.60 g
(92%), colorless prisms, mp 230 °C (ethanol).
Method b.
A solution of 3-chloro-4-hydroxy-1-methyl-2-quinolone (4)
(5.25 g, 25 mmol) and thiophenol (2.8 g, 25 mmol) in pyridine
(20 mL) was heated for 12 hours under reflux. Then the mixture
was poured onto ice-water and acidified to pH = 1. The resulting
oily product was stirred in water until solid, and then collected by
suction filtration. The yield was 7.77 g (95%), colorless platelets,
mp 230 °C (ethanol); lit mp 230-232 °C [7].
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 instru-
ment with the differential scanning calorimetry software V5.42.
The differential scanning calorimetry plots were recorded between
25 - 400 °C, with a heating rate of 2-10 °C/min, and 1.5-3 mg com-
pound in sealed aluminium crucibles (11 bar). Thermogravimetric
data were obtained with a Perkin Elmer Thermogravimetric
Analyzer TGA7. The plots were recorded between 30-450 °C, with
a heating rate of 10 °C/min, 5-12 mg compound in platinum cru-
cibles and a slow stream of nitrogen in the thermobalance. The 1H
nmr spectra were recorded on a Bruker AM 360 instrument (360
MHz). The solvent for nmr spectra was deuteriochloroform unless
4-Hydroxy-1-phenyl-3-phenylsulfanylquinolin-2(1H)-one (2b).
Compound 2b was obtained from 4-hydroxy-2-quinolone 1b
(11.85 g, 50 mmol) and diphenyldisulfide (5.45 g, 25 mmol); the
yield was 12.44 g (72%), colorless prisms, mp 181 °C (toluene);
lit mp 180-183 °C [7].
1-Hydroxy-2-phenylsulfanyl-6,7-dihydro-5H-benzo[ij]quino-
lizin-3-one (2c).
Compound 2c was obtained from 1-hydroxybenzoquinolizin-
3-one (1c) (10.0 g, 50 mmol) and diphenyldisulfide (5.45 g, 25

1262
A. E. Täubl, K. Langhans, T. Kappe and W. Stadlbauer
Vol. 39
mmol); the yield was 14.08 g (91%), colorless prisms, mp 174-
Anal. Calcd. for C18H15NO3S: C, 66.44; H, 4.64; N, 4.30; S,
9.85. Found: C, 66.28; H, 4.81; N, 4.27; S, 9.70.
1
175 °C (ethanol); ir: 1620 m, 1580 m cm-1; H nmr (deuteriodi-
methylsulfoxide): d 2.05 (q, J = 6 Hz, CH2), 3.00 (t, J = 6 Hz, Ar-
CH2), 4.05 (t, J = 6 Hz, NCH2), 7.10-7.20 (m, 4 ArH), 7.25-7.35
(m, 2 ArH), 7.45 (d, J = 7 Hz, H-8), 7.9 (dd,J = 2+7.5 Hz, H-10).
Anal. Calcd. for C18H15NO2S: C, 69.88; H, 4.89; N, 4.53; S
10.36. Found: C, 69.97; H, 4.86; N, 4.49; S 10.40.
General Procedure for the Synthesis of 4-Hydroxy-3-phenylsul-
fonylquinolin-2(1H)-ones 7a-c.
A solution of the corresponding 4-hydroxy-3-phenylsulfanyl-
2-quinolone 2a-c (20-30 mmol) in glacial acetic acid (55-80 mL)
was heated to 50 °C. Then, peracetic acid (40%, 20-30 mL) was
added at a rate such that the temperature did not exceed 75-80 °C.
The reaction mixture was then stirred at that temperature for 1
hour. The mixture was cooled to room temperature, poured onto
ice/water (300 mL) and the solid collected by suction filtration.
4-Chloro-1-methyl-3-phenylsulfanylquinolin-2(1H)-one (5).
A mixture of 4-hydroxy-1-methyl-3-phenylsulfanyl-2-
quinolone (2a) (2.83 g, 10 mmol) in phosphoryl chloride (30 mL)
was warmed to 60 °C for 2 hours. After cooling to room temper-
ature the excess phosphoryl chloride was removed in vacuo and
the residue poured onto ice/water (200 mL). The mixture was
brought to pH = 6 with sodium carbonate, the resulting oily prod-
uct stirred with water until solid and collected by filtration. The
yield was 2.05 g (94%), yellow plates, mp 169-171 °C (ethanol);
ir: 1650 s cm-1; 1H nmr: d 3.72 (s, NCH3), 7.31 (m, 7 ArH), 7.63
(t, J = 8 Hz, 1 ArH), 8.12 (dd, J = 2+8 Hz, 5-H).
4-Hydroxy-1-methyl-3-phenylsulfonylquinolin-2(1H)-one (7a).
Compound 7a was obtained from 4-hydroxy-3-phenylsul-
fanyl-2-quinolone 2a (5.67 g, 20 mmol) and peracetic acid (20
mL) in glacial acetic acid (55 mL); the yield was 5.46 g (88%),
colorless prisms, mp 246 °C (toluene); ir: 3000-3200 br, 1640 s,
1
1620 s cm-1; H nmr: d 3.44 (s, NCH3), 7.38 (t, J = 7.3 Hz, 1
ArH), 7.55 (d, J = 8.6 Hz, 1 ArH), 7.62 (t, J = 8.4 Hz, 2 ArH),
7.72 (t, J = 7.5 Hz, 1 ArH), 7.82 (t, J = 7 Hz, 1 ArH), 8.70 (d, J =
7.5 Hz, 2 ArH), 8.14 (d, J = 7 Hz, 1 ArH).
Anal. Calcd. for C16H13NO4S: C, 60.94; H, 4.16; N, 4.44.
Found: C, 60.61; H, 4.00; N, 4.35.
Anal. Calcd. for C16H12ClNOS: C, 63.68; H, 4.00; N, 4.64.
Found: C, 63.57; H, 3.82; N, 4.52.
General Procedure for the Synthesis of 4-Hydroxy-3-phenyl-
sulfinylquinolin-2(1H)-ones 6a-c.
To a solution of the corresponding 4-hydroxy-3-phenylsul-
fanyl-2-quinolone 2a-c (10-20 mmol) in 1 N aqueous sodium
hydroxide solution (40-80 mL) in a 500 mL flask, hydrogen
peroxide (30%, 20-40 mL) was added slowly to keep the tem-
perature at room temperature. After stirring for further 2 hours
at room temperature the mixture was brought to pH = 5-6 with
6 N hydrochloric acid and the formed precipitate separated by
filtration.
4-Hydroxy-1-phenyl-3-phenylsulfonylquinolin-2(1H)-one (7b).
Compound 7b was obtained from 4-hydroxy-3-phenylsul-
fanyl-2-quinolone 2b (6.91 g, 20 mmol) and peracetic acid (20
mL) in glacial acetic acid (55 mL); the yield was 6.94 g (92%),
colorless needles, mp 253 °C (acetic acid); ir: 2900-3100 br, 1660
s, 1620 s cm-1; 1H nmr: d 6.51 (d, J = 8.5 Hz, 1 ArH), 7.23 (d, J =
7 Hz, 2 ArH), 7.36 (t, J = 7 Hz, 1 ArH), 7.51-7.62 (m, 6 ArH),
7.71 (t, J = 7 Hz, 1 ArH), 8.04 (d, J = 7 Hz, 2 ArH), 8.16 (d, J = 7
Hz, 1 ArH).
4-Hydroxy-1-methyl-3-phenylsulfinylquinolin-2(1H)-one (6a).
Anal. Calcd. for C21H15NO4S: C, 66.83; H, 4.01; N, 3.71; S,
8.50. Found: C, 66.97; H, 3.87; N, 3.64; S, 8.42.
Compound 6a was obtained from 4-hydroxy-3-phenylsul-
fanyl-2-quinolone 2a (5.67 g, 20 mmol) and hydrogen perox-
ide (40 mL) in sodium hydroxide (80 mL); the yield was 5.76
g (97%), colorless prisms, mp 175 °C (ethanol); lit mp 175-
176 °C [7].
1-Hydroxy-2-phenylsulfonyl-6,7-dihydro-5H-benzo[ij]quino-
lizin-3-one (7c).
Compound 7c was obtained from 1-hydroxy-2-phenylsulfanyl-
benzo[ij]quinolizinone 2c (9.28 g, 30 mmol) and peracetic acid
(30 mL) in glacial acetic acid (80 mL); the yield was 9.37 g
(96%), colorless needles, mp 215-216 °C (dimethylfor-
4-Hydroxy-1-phenyl-3-phenylsulfinylquinolin-2(1H)-one (6b).
Compound 6b was obtained from 4-hydroxy-3-phenylsul-
fanyl-2-quinolone 2b (3.45 g, 10 mmol) and hydrogen peroxide
(20 mL) in sodium hydroxide (40 mL). The yield was 3.53 g
(98%), colorless prisms, mp 192 °C (toluene); 1640 s, 1560 s
cm-1; 1H nmr (deuteriodimethylsulfoxide): d 6.56 (d, J = 8.5
Hz, 1 ArH), 7.24 (d, J = 6.8 Hz, 1 ArH), 7.31-7.39 (m, 2 ArH),
7.54-7.64 (m, 7 ArH), 7.93-7.96 (m, 2 ArH), 8.01 (dd, J = 1.2+8
Hz, 1 ArH).
1
mamide/water); ir: 1640 s cm-1; H nmr: d 2.00 (q, J = 6.7 Hz,
CH2), 2.90 (t, J = 6.7 Hz, ArCH2), 4.00 (t, J = 6.7 Hz, NCH2),
7.10-7.70 (m, 5 ArH), 8.00-8.20 (m, 3 ArH), 12.20 (s, OH).
Anal. Calcd. for C18H15NO4S: C, 63.33; H, 4.43; N, 4.10; S,
9.39. Found: C, 62.98; H, 4.62; N, 4.11; S, 9.43.
1-Methyl-4-(4-methylphenylsulfonyloxy)-3-phenylsulfinyl-
quinolin-2(1H)-one (8a).
Anal. Calcd. For C21H15NO3S: C, 69.79; H, 4.18; N, 3.88; S,
8.87. Found: C, 69.77; H, 3.94; N, 3.76; S, 8.56.
A mixture of 4-hydroxy-3-phenylsulfinylquinolone 6a (1.50 g,
5 mmol) and p-toluenesulfonyl chloride (1.33 g, 7 mmol) in dry
pyridine (20 mL) was stirred at room temperature for 2 hours. The
reaction mixture was then poured onto ice/water (200 mL) and
formed a precipitate which was collected by suction filtration and
dried in vacuo; the yield was 0.87 g (38%), yellow prisms, mp 180
°C (toluene); 1H nmr: d 2.50 (s, CH3), 3.75 (s, NCH3), 7.15-7.45
(m, 10 ArH), 7.60-7.73 (m, 1 ArH), 7.85-8.05 (m, 2 ArH).
Anal. Calcd. for C23H19NO5S2: C, 60.91; H, 4.22; N, 3.09.
Found: C, 60.70; H, 4.23; N, 3.25.
1-Hydroxy-2-phenylsulfinyl-6,7-dihydro-5H-benzo[ij]quino-
lizin-3-one (6c).
Compound 6c was obtained from 1-hydroxy-2-phenylsulfanyl-
benzoquinolizin-3-one 2c (3.09 g, 10 mmol) and hydrogen per-
oxide (20 mL) in sodium hydroxide (40 mL). The yield was 2.92
g (90%), colorless prisms, mp 175 °C (ethanol); ir: 1620 m, 1580
m cm-1; 1H nmr: d 2.00-2.15 (m, CH2), 2.85-3.00 (t, J = 6.5 Hz,
Ar-CH2), 4.05 (t, J = 6.5 Hz, NCH2), 7.05-7.50 (m, 5 ArH), 7.80-
8.05 (m, 3 ArH).

Nov-Dec 2002
Thermolytic Ring Closure Reactions
1263
4-(4-Methylphenylsulfonyloxy)-1-phenyl-3-phenylsulfinyl-
quinolin-2(1H)-one (8b).
ArH), 7.67-7.71 (m, 1 ArH), 8.00 (d, J = 7 Hz, 2 ArH), 8.15 (d,
J = 7.5 Hz, 1 ArH).
Anal. Calcd. for C18H14ClNO3S: C, 60.08; H, 3.92; N, 3.89.
Found: C, 59.79; H, 3.79; N, 3.81.
A mixture of 4-hydroxy-3-phenylsulfinylquinolone6b (1.52 g,
8 mmol) and p-toluenesulfonyl chloride (1.90 g, 10 mmol) in dry
triethylamine (20 mL) was reacted and worked up as described
for 8a; the yield was 1.34 g (52%), yellow-orange prisms, mp
192 °C (ethanol); 1H nmr: d 2.47 (s, CH3), 6.60 (d, J = 8.5 Hz, 1
ArH), 7.11-7.68 (m, 15 ArH), 7.95 (d, J = 8 Hz, 1 ArH), 8.03 (d,
J = 8 Hz, 1 ArH).
4-Azido-1-methyl-3-phenylsulfanylquinolin-2(1H)-one (10).
A mixture of 4-chloro-1-methyl-3-phenylsulfanylquinolin-
2(1H)-one (5) (1.51 g, 5 mmol) and sodium azide (0.98 g, 15
mmol) in dimethylformamide (20 mL) was warmed to 60 °C for
6 hours. Then the mixture was cooled to room temperature and
poured onto ice/water (150 mL), the formed precipitate was sep-
arated by filtration and washed with water (100 mL). The yield
was 1.42 g (92%), colorless platelets, mp 152-153 °C (dec);
calorimetric data for thermolysis: reaction/decomposition onset
at 130 °C, peak maximum 149 °C, DH = -194 mcal/mg, mp 325.2
°C (11); ir: 2105 s, 1645 s; 1H nmr: d 3.72 (s, CH3), 7.28 (m, 7
ArH), 7.63 (t, J = 8 Hz, 1 ArH), 8.04 (dd, J = 2+8 Hz, H-5).
Anal. Calcd. for C16H12N4OS: C, 62.32; H, 3.92; N, 18.17.
Found: C, 61.98; H, 3.74; N, 18.15.
Anal. Calcd. for C28H21NO5S2: C, 65.23; H, 4.11; N, 2.72.
Found: C, 64.85; H, 3.93; N, 3.11.
1-(4-Methylphenylsulfonyloxy)-2-phenylsulfinyl-6,7-dihydro-
5H-benzo[ij]quinolizin-3-one (8c).
A mixture of 1-hydroxy-2-phenylsulfinylbenzoquinolizin-3-
one 6c (1.63 g, 5 mmol) andp-toluenesulfonyl chloride (1.33 g, 7
mmol) in dry pyridine (20 mL) was reacted and worked up as
described for 8a; the yield was 1.06 g (44%), colorless prisms,
1
mp 217 °C (ethanol); H nmr: d 2.10 (q, CH2), 2.45 (s, CH3),
3.00 (t, J = 6 Hz, Ar-CH2), 4.15 (t, J = 6 Hz, NCH2), 7.10-7.45
(m, 9 ArH), 7.80-7.95 (m, 3 ArH).
Anal. Calcd. for C25H21NO5S2: C, 62.61; H, 4.41; N, 2.92.
Found: C, 62.13; H, 4.76; N, 2.97.
5-Methyl-12H-quinolino[3,4-b][1,4]benzothiazin-6(5H)-one
(11).
A solution of 4-azido-1-methyl-3-phenylsulfanyl-2-quinolone
(10) (1.37 g, 4.4 mmol) in xylene (50 mL) was heated under
reflux for 30 minutes. During this period, nitrogen was evolved
and the color of the solution changed first to yellow and then a
light brown solid precipitated. The solvent was removed in vacuo
and the residue dried at 40 °C. The yield was 1.21 g (97%), light
brown needles, mp 324-325 °C; lit mp. >310 °C [8]; ir: 3340 m,
1625 m, 1605 m, 1575 s; 1H nmr (deuteriodimethylsulfoxide): d
3.58 (s, CH3), 6.89 (m, 4 ArH), 7.48 (m, 3 ArH), 8.11 (dd, J =
2+8 Hz, 1-H), 8.48 (s, 1 NH).
4-Chloro-1-methyl-3-phenylsulfonylquinolin-2(1H)-one (9a).
Dry triethylamine (5 mL) was added to a solution of
4-hydroxy-3-phenylsulfonyl-2-quinolone 7a (4.73 g, 15 mmol)
in phosphoryl chloride (50 mL), the mixture was heated under
reflux for 1 hour and then the excess phosphoryl chloride
removed in vacuo. The residue was poured onto ice/water (300
mL) and brought to pH = 6 with concentrated aqueous sodium
hydroxide. The precipitate was collected by suction filtration and
washed with water; the yield was 4.90 g (98%), pale brown
prisms, mp 217 °C (ethanol); ir: 1640 s, 1600 s 1530 m cm-1; 1H
nmr (deuteriodimethylsulfoxide): d 3.50 (s, NCH3), 7.46 (t, J = 8
Hz, 1 ArH), 7.58-7.71 (m, 4 ArH), 7.86 (t, J = 8.5 Hz, 1 ArH),
8.00 (d, J = 7.3 Hz, 2 ArH), 8.31 (d, J = 8.3 Hz, 1 ArH).
Anal. Calcd. for C16H12N2OS: C, 68.55; H, 4.31; N, 9.99.
Found: C, 68.30; H, 4.02; N, 9.89.
4-Azido-1-methyl-3-phenylsulfonylquinolin-2(1H)-one (12a).
A suspension of the 4-chloro-3-phenylsulfonyl-2-quinolone9a
(1.67 g, 5 mmol) and sodium azide (0.50 g, 7 mmol) in N-
methylpyrrolidone (30 mL) was stirred at room temperature for 4
hours. The reaction mixture was then poured onto ice/water (100
mL), the mixture was allowed to stand for 12 hours and then the
precipitate was collected by suction filtration; the yield was 1.56
g (92%), pale brown prisms, mp 183 °C (dec) (toluene); calori-
metric data for thermolysis: reaction/decomposition onset at 173
°C, peak maximum 183 °C, DH = -127 mcal/mg; ir: 3100 w, 2250
w, 2120 s, 1680 s cm-1; 1H nmr: d 3.55 (s, NCH3), 7.25-7.40 (m,
2 ArH), 7.50-7.80 (m, 4 ArH), 8.15 (d, J = 7.5 Hz, 2 ArH), 8.30
(d, J = 7.5 Hz, 1 ArH).
Anal. Calcd. for C16H12ClNO3S: C, 57.57; H, 3.62; N, 4.20.
Found: C, 57.41; H, 3.59; N, 4.11.
4-Chloro-1-phenyl-3-phenylsulfonylquinolin-2(1H)-one (9b).
Compound 9b was obtained from 4-hydroxy-3-phenylsul-
fonylquinolone 7b (3.77 g, 15 mmol), dry triethylamine (4 mL)
and phosphoryl chloride (40 mL) as described for 9a; the yield
was 3.30 g (89%), pale brown needles, mp 299 °C (toluene); ir:
3050 w, 1670 s, 1600 s 1530 m cm-1; 1H nmr (deuteriodimethyl-
sulfoxide): d 6.60 (d, J = 7.5 Hz, 1 ArH), 7.25-7.35 (m, 2 ArH),
7.45-7.70 (m, 8 ArH), 8.00 (d, J = 7.5 Hz, 2 ArH), 8.40 (d, J = 7.5
Hz, 1 ArH).
Anal. Calcd. for C16H12N4O3S: C, 56.46; H, 3.55; N, 16.46.
Found: C, 56.85; H, 3.57; N, 16.16.
Anal. Calcd. for C21H14ClNO3S: C, 63.72; H, 3.56; N, 3.54.
Found: C, 64.06; H, 3.55; N, 3.46.
4-Azido-1-phenyl-3-phenylsulfonylquinolin-2(1H)-one (12b).
1-Chloro-2-phenylsulfonyl-6,7-dihydro-5H-benzo[ij]quinolizin-
3-one (9c).
It was obtained from 4-chloro-3-phenylsulfonyl-2-quinolone
9b (1.90 g, 5 mmol) according to the procedure described for
12a; the yield was 1.69 g (84%), pale brown prisms, mp 190 °C
(ethanol); calorimetric data for thermolysis: reaction/decomposi-
tion onset at 187 °C, peak maximum 190 °C, DH = -160
mcal/mg; ir: 3050 w, 2120 s, 1660 s cm-1; 1H nmr: d 6.60 (d, J =
7.5 Hz, 1 ArH), 7.10 (d, J = 7.5 Hz, 2 ArH), 7.25-7.35 (m, 1
ArH), 7.40-7.60 (m, 7 ArH), 8.10 (dd, J = 1.5+7.5 Hz, 2 ArH),
8.30 (dd, J = 1.5+7.5 Hz, 5-H).
Compound 9c was obtained from 1-hydroxy-2-phenylsul-
fonylbenzoquinolizin-3-one 7c (3.25 g, 10 mmol), dry triethy-
lamine (4 mL) and phosphoryl chloride (40 mL) as described for
9a; the yield was 3.30 g (93%), pale colorless needles, mp 215 °C
1
(ethanol); ir: 1640 s, 1530 s cm-1; H nmr (deuteriodimethylsul-
foxide): d 1.93-1.98 (m, CH2), 2.92 (t, J = 6 Hz, Ar-CH2), 3.90 (t,
J = 6 Hz, NCH2), 7.36 (t, J = 7.5 Hz, 1 ArH), 7.58-7.63 (m, 3

1264
A. E. Täubl, K. Langhans, T. Kappe and W. Stadlbauer
Vol. 39
Anal. Calcd. for C21H14N4O3S: C, 62.68; H, 3.51; N, 13.92; S,
7.97. Found: C, 62.71; H, 3.60; N, 13.70; S, 7.82.
0.440 g (93%), brown prisms, mp 223 °C (dimethylformamide);
1
ir: 3320 m, 1630 s cm-1; H nmr (deuteriodimethylsulfoxide): d
2.00 (m, CH2), 2.96 (m, Ar-CH2), 4.00 (m, NCH2), 7.30 (t, J =
7.5 Hz, 1 ArH), 7.39 (t, J = 7.5 Hz, 1 ArH), 7.56 (d, J = 7.1 Hz, 1
ArH), 7.68 (t, J = 7.5 Hz, 1 ArH), 7.77 (d, J = 8.3 Hz, 1 ArH),
7.92 (d, J = 7.6 Hz, 1 ArH), 8.39 (d, J = 8.7 Hz, 1 ArH), 10.70 (s,
NH).
1-Azido-2-phenylsulfonyl-6,7-dihydro-5H-benzo[ij]quinolizin-
3-one (12c).
Compound 12c was obtained from 1-chloro-2-phenylsulfonyl-
benzoquinolizin-3-one 6c (1.83 g, 5 mmol) according to the pro-
cedure described for 12a; the yield was 1.46 g (80%), pale brown
prisms, mp 164 °C (ethanol); calorimetric data for thermolysis:
reaction/decomposition onset at 156 °C, peak maximum 164 °C,
DH = -154 mcal/mg; ir: 2950 w, 2200 m, 2140 s, 1640 s cm-1; 1H-
nmr: d 1.95-2.05 (m, CH2), 2.95 (t, J = 6 Hz, Ar-CH2), 4.00 (t,
J = 6 Hz, NCH2), 7.15-7.25 (m, 1 ArH), 7.40-7.60 (m, 4 ArH),
8.00-8.20 (m, 3 ArH).
Anal. Calcd. for C18H14N2O3S: C, 63.89; H, 4.17; N, 8.28; S,
9.48. Found: C, 64.03; H, 4.26; N, 8.66; S, 9.83.
Acknowledgement.
We thank Dr. G. Faleschini, Division of Inorganic Chemistry,
Department of Chemistry, Karl-Franzens University of Graz, for
thermogravimetric measurements.
Anal. Calcd. for C18H14N4O3S: C, 59.01; H, 3.85; N, 15.29.
Found: C, 59.15; H, 3.82; N, 15.22.
REFERENCES AND NOTES
5-Phenyl-12H-quinolino[3,4-b][1,4]benzothiazin-6(5H)-one 7,7-
dioxide (13b).
[1] Organic Azides in Heterocyclic Synthesis, Part 31. Part 30: W.
Stadlbauer and G. Hojas, J. Biochem. Biophys. Methods (2002), in press.
[2] P. A. S. Smith, in "Azides and Nitrenes", E. F. V. Scriven, ed.,
Academic Press, Orlando, Florida, 1984; E. F. V. Scriven and 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 and A. Padwa, in "Organic
Synthesis: Theory and Applications", Vol. 3, 149, T. Hudlicky, ed., JAI
Press Inc., Greenwich/USA - London, 1996.
A suspension of 4-azidoquinolone 12b (0.310 g, 0.8 mmol) in
dichlorobenzene (3 mL) was heated under reflux for 10 minutes.
During this time evolution of nitrogen gas could be observed.
The mixture was cooled to room temperature and quenched with
hexane. The formed solid was collected by suction filtration and
washed with hexane; the yield was 0.250 g (83%), brown prisms,
1
mp 210 °C (dimethylformamide); ir: 3320 m, 1660 s cm-1; H
nmr (deuteriodimethylsulfoxide): d 6.58 (d, J = 8.3 Hz, 1 ArH),
7.36 (d, J = 7.5 Hz, 1 ArH), 7.44 (t, J = 7.3 Hz, 2 ArH), 7.58-7.66
(m, 5 ArH), 7.74 (t, J = 7.3 Hz, 1 ArH), 7.84 (d, J = 8.3 Hz, 1
ArH), 7.95 (d, J = 8.0 Hz, 1 ArH), 8.60 (d, J = 8 Hz, 1 ArH),
10.90 (s, NH).
[3] W. Stadlbauer and M. Fischer, J. Heterocyclic Chem., 39, 131
(2002).
[4] W. Stadlbauer., W. Fiala, M. Fischer, and G. Hojas, J. Prakt.
Chem - Chem. Ztg., 342, 33 (2000).
[5] W. Stadlbauer,Monatsh. Chem., 118,1297 (1987).
[6] Th. Kappe, B. Schnell, K. Georgieva, B. Jocham, A. E.
Mayrhofer, B. P. Nikam, Y. Issac and K. Langhans, Phosphorus, Sulfur,
Silicon and Rel. Elem., 95/96, 349 (1994).
Anal. Calcd. for C21H14N2O3S: C, 67.37; H, 3.77; N, 7.48.
Found: C, 67.04; H, 3.66; N, 7.44.
[7] B. Schnell and Th. Kappe, Monatsh. Chem., 130, 1147 (1999.
[8] A. Jajashree, V. Sudhakar Rao and M. Darbarwar, Synth.
Comm., 20, 919 (1990).
[9] P. Roschger, W. Fiala and W. Stadlbauer, J. Heterocyclic
Chem., 29, 225 (1992).
4,5,6,14-Tetrahydrobenzo[9,10]quinolizino[3,2-b][1,4]benzoth-
iazin-8-one 9,9-Dioxide (13c).
A suspension of 1-azido-2-phenylsulfonylbenzoquinolizin-3-
one (12c) (0.500 g, 1.4 mmol) in 1,2-dichlorobenzene (7 mL)
was reacted and worked up as described for 12b; the yield was
[10] H. Wittmann, Monatsh. Chem., 96, 523 (1965).