Novel synthesis of 4H-quinolizine derivatives using sulfonyl ketene dithioacetals

Article abstract of DOI:10.1002/ejoc.200900783

In the synthesis of 4H-quinolizine derivatives involving the use of a sulfonyl ketene dithioacetal, we found a novel reaction in which the remaining methylsulfanyl group was replaced with a proton after the ring-closure reaction in the quinolizine skeleto

Full text of DOI:10.1002/ejoc.200900783

FULL PAPER
DOI: 10.1002/ejoc.200900783
Novel Synthesis of 4H-Quinolizine Derivatives Using Sulfonyl Ketene
Dithioacetals
Masayori Hagimori,[a] Sayaka Matsui,[b] Naoko Mizuyama,[c] Kenichirou Yokota,[b]
Junko Nagaoka,[d] and Yoshinori Tominaga*[b]
Keywords: Nitrogen heterocycles / Sulfur / Fluorescence / Organic light-emitting diodes
In the synthesis of 4H-quinolizine derivatives involving the
use of a sulfonyl ketene dithioacetal, we found a novel reac-
tion in which the remaining methylsulfanyl group was re-
placed with a proton after the ring-closure reaction in the
quinolizine skeleton under mild conditions, without the use
of any metallic reagent. The reaction of 3,3-bis(methylsul-
fanyl)-2-phenylsulfonylacrylonitriles (1a,b) with 2-pyridyl-
acetonitrile (2a) in the presence of potassium carbonate as a
base in DMSO afforded 4-imino-2-methylsulfanyl-3-phenyl-
sulfonyl-4H-quinolizine-1-carbonitriles (3a,b). The methyl-
sulfanyl group at the 2-position of 3a,b was readily removed
under methanol reflux conditions to afford 4-imino-3-phenyl-
sulfonyl-4H-quinolizine-1-carbonitriles (4a,b) in good yields.
Alkyl 3-phenylsulfonyl-4H-quinolizine-1-carboxylates (4c–f)
were directly synthesized from sulfonyl ketene dithioacetal
(1a,b) with alkyl 2-pyridylacetates (2b,c) and involved desul-
fanylation by simple hydrolysis. In addition, the fluorescent
properties of these compounds were investigated.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
corresponding heterocycles contain one methylsulfanyl
group. In the synthesis of 4H-quinolizine derivatives, we
found a novel reaction in which the remaining methylsul-
fanyl group of the quinolizine skeleton was replaced with a
proton after the ring-closure reaction under mild condi-
tions, without the use of any metallic reagent.[4] In this pa-
per, we report the synthesis of 4-imino-4H-quinolizine de-
rivatives by a novel synthesis method involving the use of a
ketene dithioacetal, and the fluorescent properties of these
derivatives is discussed.
Introduction
Appropriately functionalized ketene dithioacetals (cyano,
methoxycarbonyl, sulfonyl, nitro, acyl) are versatile reagents
that have been extensively utilized as building blocks in het-
erocyclic synthesis.[1] The sulfonyl ketene dithioacetals 3,3-
bis(methylsulfanyl)-2-phenylsulfonyl acrylonitriles (1a,b)
are used as two- or three-carbon fragments for the synthesis
of heterocyclic compounds having sulfonyl or cyano groups.
These ketene dithioacetals are readily prepared by the con-
densation of phenylsulfonyl acetonitriles with carbon disul-
fide in the presence of sodium hydroxide, followed by meth-
ylation with dimethyl sulfate.[2] It has been reported that 4-
imino-2-methylsulfanyl-4H-quinolizine derivatives are syn-
thesized from the corresponding 2-pyridylacetonitrile and
ketene dithioacetals under basic conditions. Some of these
4H-quinolizine derivatives exhibit fluorescence, and as
such, these compounds have attracted significant attention
owing to their possible applications as photographic materi-
als and dyes.[3] In general, in ketene dithioacetals having
two methylsulfanyl groups, one of the methylsulfanyl
groups is eliminated in the reaction, and consequently, the
Results and Discussion
The reaction of 3,3-bis(methylsulfanyl)-2-(phenylsulfon-
yl)acrylonitrile (1a)[2] with 2-pyridylacetonitrile (2a) in the
presence of potassium carbonate (base) in dimethyl sulfox-
ide (DMSO) at room temperature for 4 h afforded the ex-
pected product, 4-imino-2-methylsulfanyl-3-phenylsulfonyl-
4H-quinolizine-1-carbonitrile
(3a),
in
82%
yield
(Scheme 1). Compound 3a was presumed to be formed by
the addition of a nucleophile to a ketene dithioacetal, elimi-
nation of a methylsufanyl group, and subsequent cycliza-
tion; further, 3a was readily converted into 4-imino-3-phen-
ylsulfoyl-4H-quinolizine-1-carbonitrile (4a) by the elimi-
nation of a methylsulfanyl group in quantitative yield under
reflux for 5 h in methanol (Scheme 2). When ammonia or
aqueous NaOH solution was substituted for methanol, the
desired product was not obtained. Compounds 3b and 4b
were also prepared from 1b and 2a, respectively, in a man-
ner similar to that described for the preparation of 3a and
4a. In the methylsulfanyl group in compounds 3a,b, there
[a] Faculty of Pharmaceutical Sciences, Nagasaki International
University,
2825-7, Huis Ten Bosch, Sasebo 859-3298, Japan
Fax: +81-956-39-3111
E-mail: mhagimori@niu.ac.jp
[b] Faculty of Environmental Studies, Nagasaki University,
1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
[c] Department of Hospital Pharmacy, Saga University Hospital,
5-1-1, Nabeshima, Saga 849-8521, Japan
[d] Faculty of Engineering, Nagasaki University,
1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
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Y. Tominaga et al.
FULL PAPER
is a strong interaction between the sulfur of the methylsul- group. We synthesized 4d–f in a similar manner from the
fanyl group and an oxygen in the sulfonyl group.[5] The corresponding sulfonyl ketene dithioacetals (1a,b) and 2-
methylsulfanyl groups in compounds 3a,b are readily at- pyridylacetates (2b,c; Table 1).
tacked by nucleophilic molecules such as water or meth-
Table 1. Reaction of 2-pyridylacetates 2b,c with sulfonyl ketene di-
anol, and protonation at the 2-position of compound 3 oc-
thioacetals 1a,b in the presence of a base.
curred to produce 4a,b in good yields.
Starting material
Product
R1
R2
M.p.[°C] Yield [%]
1a + 2b
1b + 2b
1a + 2c
1b + 2c
4c
4d
4e
4f
Me
Me
Et
H
Me
H
203–205
216–218
152–155
177–178
47
41
46
48
Et
Me
The key step of this reaction was the displacement of the
methylsulfanyl group at the 2-position by a proton after the
ring-closure reaction in the quinolizine skeleton. A part of
the pyridine ring in the quinolizine skeleton becomes elec-
Scheme 1. Synthesis of 3a,b and 4a,b.
When compound 1a was allowed to react with methyl 2- tron deficient due to electron-withdrawing groups (e.g., cy-
pyridylacetate (2b) under reaction conditions identical to ano, sulfonyl, and imino groups), and a sulfur atom of the
those in the preparation of 3a, methyl 4-imino-3-phenylsul- methylsulfanyl group becomes electron deficient due to
fonyl-4H-quinolizine-1-carboxlate (4c) was obtained from strong interaction between the sulfur atom of the methylsul-
the basic solution. Compound 4c exhibited absorption fanyl group and an oxygen atom of the sulfonyl group.[6]
bands in the infrared spectrum at 3336 and 1702 cm–1 due Calculation of atomic partial charges by the AM1 method
to the imino and carbonyl groups, respectively, and no ab- of MOPAC supported the hypothesis that the intramolecu-
sorption band due to the cyano group. In this case, 4-imino- lar interaction between the sulfur atom of the methylsul-
2-methylsulfonyl-4H-quinolizine derivatives such as 3a,b fanyl group and an oxygen atom of the neighboring sulfonyl
were not obtained in any reaction mixture. In the 1H NMR group causes the electron deficiency of the sulfur atom.[7]
spectra, a signal for the proton could be assigned to the C- S–O interaction and the electron-deficient effect in the pyr-
2 proton at δ = 8.86 ppm rather than to the methylsulfanyl idine ring enables nucleophilic attack of water or methanol
Scheme 2. Presumed reaction pathway for the synthesis of 4a,b.
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Synthesis of 4H-Quinolizine Derivatives by Sulfonyl Ketene Dithioacetals
anions on the sulfur atom in the methylsulfanyl group. The
“desulfanylation reaction” is easily initiated if the cyano
group at the 1-position on the quinolizine ring is changed
into a methyl or an ethyl ester group. In this case, when the
reaction mixture was poured into water, the desulfanylated
products were directly obtained from the alkali solution.
An interaction effect between the oxygen atom of the car-
bonyl group of an ester and a sulfur atom of the methylsul-
fanyl group was produced in these reactions, but the reac-
tion yield did not exceed 50%.
After removing pure product 4c, the filtrate was acidified
with 10% hydrogen chloride solution to afford red crystals
in 48% yield. The 1H NMR spectrum of this product exhib-
ited signals corresponding to hydrogen bonding between
the NH group and an ester carbonyl group at δ =
14.20 ppm and methyl protons of the methylsulfanyl group
at δ = 2.14 ppm and methyl protons of the tolyl group at δ
1
= 3.39 and 3.51 ppm (ratio 1:1). The H NMR signals re-
vealed that the ring-closure reaction did not take place in
this case. After purification, the isolated product was iden-
Figure 1. ORTEP drawing of 5b.
tified (on the basis of IR, UV, and NMR spectroscopy, used in devices and elsewhere.[10] There remains an interest
mass spectrometry, and elemental analysis) as a mixture of in the fluorescence of compounds with a quinolizine skel-
5a and 6a (ratio 1:1), which are E and Z isomers of the eton. The fluorescence of synthesized 4-imino-3-phenylsul-
methyl (2Z,3E)-4-cyano-3-methylsulfanyl-4-phenylsulfonyl- fonyl-4H-quinolizine derivatives in the solid state is of great
2-(1H-pyrid-2-ylidene)butenoate. Compounds 5b–d and 6b– interest to our research group.
d were also synthesized from 1a,b and 2b,c in a similar man-
The UV/Vis absorption and fluorescence emission data
ner to 5a and 6a (Table 2). The X-ray analysis of 5b conclu- of 3a,b and 4a–f were analyzed in solution (dichlorometh-
sively established that the structure of this compound is that ane) and in the solid state, respectively, at room temperature
shown in Figure 1. These products were not converted into (Table 3). The spectroscopic properties Ϫ absorption max-
quinolizine derivatives under basic or acidic reaction condi- ima (λmax), molar absorptivities (ε), fluorescence maxima
tions in DMSO.
(λEm-max), and relative fluorescent intensities (RI) Ϫ are
listed in Table 3. The λEm-max of 3a,b and 4a–f were in the
range 507–522 nm in dichloromethane and 528–564 nm in
the solid state. With regard to λEm-max, the obvious substitu-
tion effects at the 1- or 2-position of the 4H-quinolizine
ring were not observed. In contrast, the RIs of 4a,b were
slightly stronger than those of 3a,b in dichloromethane and
in the solid state, indicating that desulfanylation at the 2-
position of the 4H-quinolizine influenced the RI. Com-
pounds 4c–f exhibited strong fluorescence in the solid
states; in particular, 4c–e emitted stronger fluorescence than
Alq3. This suggests that the ester groups at the 1-position
have a significant effect on the fluorescent intensity. In
dichloromethane solutions of 4c–f, the obvious substitution
effects on the RI were not observed. Compounds 3a,b and
4a–f exhibited significantly larger Stokes’ shifts (SS) in
dichloromethane, indicating that the S1 states of these com-
pounds were stabilized by a solvent polarization field. The
Table 2. Synthesis of 5a–d and 6a–d.
Starting material
Prod-
uct
R1
R2 M.p.[°C] Yield [%] (5: 6)
1a + 2b
1b + 2b
1a + 2c
1b + 2c
5a, 6a
5b, 6b
5c, 6c
5d, 6d
Me
Me
Et
H
203–205
Me 165–168
143–146
Me 132–135
47 (1:1)
19 (1:1)
44 (1:1)
44 (1:1)
H
Et
Schwarz et al. carried out detailed research on the UV/ F value, which is the difference between the λEm values in
Vis spectra of quinolizine derivatives.[8] Other authors car- the solid and solution states, varied from 17 to 44 nm in all
ried out research on the synthesis of 4H-quinolizines in compounds. The crystal structures of compounds 4a,c were
studies of [3.3.3]cyclazine derivatives,[9] but fluorescence determined by X-ray crystallographic analysis. Single crys-
was not investigated. An organic light-emitting diode tals of 4a,c were obtained by recrystallized from MeOH and
(OLED) that emits light in the solid state was recently in- acetonitrile. The crystal analysis of 4a,c as shown in Fig-
vestigated. The fused 2-pyrone derivative, namely, the pyr- ures 2 and 3 suggests that π–π stacking interactions of the
ano[3,4-d]quinolizine derivative, exhibits red fluorescence in aromatic rings do not exist. In these 4H-quinolizine deriva-
the solid state; however, previously synthesized fluorescent tives, the packing structure does not affect the solid-state
materials were not able to show sufficient fluorescence when fluorescence.
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Table 3. UV and fluorescence data for 4H-quinolizine derivatives in dichloromethane and in the solid state.
λmax (loge)[a] [nm] λEx [nm]
λEm [nm]
CH2Cl2
SS[b]
RI[c]
λEx [nm]
Solid
λEm [nm]
Solid
SS[d]
RI[e]
∆F[f]
CH2Cl2
3a
3b
4a
4b
4c
4d
4e
4f
283 (3.26)
279 (3.97)
282 (3.41)
279 (3.85)
272 (3.55)
271 (4.19)
272 (4.19)
272 (3.34)
262
262
262
271
283
280
284
284
520
522
520
513
507
511
511
519
258
260
258
242
224
231
227
235
0.25
0.36
0.31
0.42
0.40
0.47
0.47
0.25
344
333
339
344
342
340
339
332
564
552
546
556
540
533
528
536
220
219
207
212
198
193
189
204
0.07
0.09
0.09
0.20
1.46
1.17
1.44
0.62
44
30
26
43
33
22
17
17
[a] Measured in ethanol. [b] Stokes’ Shift, λEm – λEx (in solution). [c] Relative intensity of fluorescence in solution, determined by using
DCM as the standard compound. [d] Stokes’ shift, λEm – λEx (in the solid state). [e] Relative intensity of fluorescence in the solid state
determined by using Alq3 as the standard compound. [f] ∆F = λEm (solid) – λEm (solution).
ketene dithioacetal (1a,b) with alkyl 2-pyridylacetates (2b,c),
under mild conditions (methanolysis or hydrolysis), without
the use of any metallic reagents. The synthesized 4-imino-3-
phenylsulfonyl-4H-quinolizine derivatives exhibited strong
fluorescence in the solid state, suggesting that it is possible
to obtain a design for enhancing fluorescence intensity
without changing their fluorescence wavelength.
Experimental Section
General Procedures: Identifications of compounds and measure-
ments of properties were carried out by general procedures using
the following equipment. Melting points were determined in a cap-
Figure 2. X-ray crystal structure of 4a.
illary tube and were uncorrected. IR spectra were recorded in po-
tassium bromide pellets on a JASCO 810 or Shimazu IR-460 spec-
trometer. UV absorption spectra were determined in 95% ethanol
on a Hitachi 323 spectrometer. Fluorescence spectra were deter-
mined on Shimazu RF-5300pc. NMR spectra were obtained on
Gemini 300NMR (300 MHz) and Varian Unityplus 500NMR
(500 MHz) spectrometers using tetramethylsilane as the internal
standard. Mass spectra (MS) were recorded on JEOL-DX-303
mass spectrometers. Microanalyses were performed by K. Yoshida
on a Perkin–Elmer at Nagasaki University. All compounds were
reagent grade and used without further purification unless other-
wise specified.
Method of Measurement of Fluorescence
In the Solid State: A powder sample of the subject compound was
heaped in a tray. After covering the sample with a quartz plate,
this part was fixed in a fluorescence spectrometer. After fixing the
Figure 3. X-ray crystal structure of 4c.
fluorescent wavelength, the excitation spectrum was determined by
scanning with the fluorescent wavelength. Similarly, the fluorescent
spectrum was obtained after scanning with the excitation wave-
length. After obtaining these results, the excitation wavelength was
decided and the fluorescence spectrum was measured. The fluores-
cent relative intensity was determined by using Alq3 as the stan-
dard.[11] The fluorescence of Alq3 and test compounds was mea-
sured at an excitation wavelength of 345 nm.
Conclusions
The reaction of 3,3-bis(methylsulfanyl)-2-phenylsulfon-
ylacrylonitriles (1a,b) with 2-pyridiylacetonitrile (2a) in the
presence of potassium carbonate as a base in DMSO af-
forded 4-imino-2-methylsulfanyl-3-phenylsulfonyl-4H-quin-
olizine-1-carbonitriles (3a,b). A methylsulfanyl group at the
2-position on the 4H-quinolizine-1-carbonitriles was readily
removed under methanol reflux conditions to afford 4-
imino-3-phenylsulfonyl-4H-quinolizine-1-carbonitriles (4a,b)
in good yields. Alkyl 3-phenylsulfonyl-4H-quinolizine-1-
In Solution: The fluorescence spectra in solution were obtained in
a manner similar to that described for the measurement in the solid
state. The relative intensity of fluorescence in solution was deter-
mined by using DCM and [4-(dicyanomethylene)-2-methyl-6-(4-di-
methylaminostyryl)-4H-pyran] as a standard compound.[12] Fluo-
rescence spectra of a standard sample and all subject compounds
were measured in CH2Cl2 solution (1.0ϫ10–5 ) at 480 nm exci-
carboxylates (4c–f) were directly synthesized from sulfonyl tation.
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Synthesis of 4H-Quinolizine Derivatives by Sulfonyl Ketene Dithioacetals
4-Imino-2-methylsulfanyl-3-phenylsulfonyl-4H-quinolizine-1-carbo- (0.37 g, 1.0 mmol) in a manner similar to that described for the
nitrile (3a): A mixture of 1a (2.53 g, 10.0 mmol), 2-pyridylacetoni-
trile (2a; 1.77 g, 10.0 mmol), and potassium carbonate (3.44 g,
20.0 mmol) in DMSO (30 mL) was stirred for 2 h at room tempera-
ture. This mixture was stirred and heated for 30 min at 50–60 °C.
The reaction mixture was poured into ice water (200 mL) and acidi-
fied with 10% hydrochloric acid. The precipitate that appeared was
collected by filtration, washed with water, and recrystallized from
MeOH/toluene (1:5) to give yellow crystals (2.91 g, 8.20 mmol,
synthesis of 4a. An analytical sample was recrystallized from DMF
to give orange needles. M.p. 180–184 °C. IR (KBr): ν = 3347
˜
(C=NH), 2208 (CN), 1614, 1490, 1292, 1095, 570 cm–1. UV
(EtOH): λ (logε) = 451.5 (3.67), 383.0 (3.65), 328.5 (3.41), 278.5
(3.85) nm. Fluorescence (solid): λEx = 344 nm; λEm = 556 nm; RI
= 0.20. Fluorescence (CH2Cl2): λEx = 271 nm; λEm = 513 nm; RI
1
= 0.42. H NMR (300 MHz, CDCl3): δ = 2.41 (s, 3 H, Me), 7.21
(m, 1 H, 7-H), 7.32 (m, 2 H, phenyl-H), 7.81 (m, 1 H, 8-H), 7.83
(m, 2 H, phenyl-H), 7.86 (d, J = 6.6 Hz, 1 H, 6-H), 8.26 (s, 1 H,
2-H), 8.78 (br. s, 1 H, NH), 9.61 (d, J = 7.8 Hz, 1 H, 9-H) ppm.
13C NMR (100 MHz, CDCl3): δ = 21.57, 80.04, 115.18, 116.62,
117.28, 122.43, 127.10, 127.22, 129.22, 131.27, 138.82, 144.07,
147.41, 150.41, 151.45 ppm. MS: m/z (%) = 324 (5) [M + 1]+, 323
(23) [M]+, 259 (21), 258 (100), 168 (25), 167 (33), 114 (13).
82 % yield). M.p. 203–204 °C. IR (KBr): ν = 3329 (NH), 2209
˜
(CN), 1610, 1140, 768 cm–1. UV (EtOH): λ (logε) = 399.0 (2.66),
309.0 (2.29), 282.5 (3.26) nm. Fluorescence (solid): λEx = 344 nm;
λEm = 564 nm; RI = 0.07. Fluorescence (CH2Cl2): λEx = 262 nm;
1
λEm = 520 nm; RI = 0.25. H NMR (300 MHz, CDCl3): δ = 2.26
(s, 3 H, SMe), 7.20–7.26 (m, 1 H, 7-H), 7.44–7.56 (m, 3 H, phenyl-
H), 7.60 (m, 1 H, 8-H), 7.82 (m, 2 H, phenyl-H), 7.99 (d, J = C17H13N3O2S (323.37): calcd. C 63.14, H 4.05, N 12.99; found C
7.8 Hz, 1 H, 6-H), 9.77 (d, J = 7.8 Hz, 1 H, 9-H), 10.11 (s, 1 H,
N-H) ppm. 13C NMR (100 MHz, CDCl3): δ = 19.63, 85.74, 115.74,
116.58, 117.36, 122.50, 127.06, 128.66, 131.99, 133.09, 138.94,
143.13, 147.53, 150.53, 151.67 ppm. MS: m/z (%) = 356 (6) [M +
1]+, 355 (28) [M]+, 309 (29), 229 (27), 290 (100), 244 (81), 214 (38),
167 (95), 78 (26). C17H13N3O2S2 (355.434): calcd. C 57.45, H 3.69,
N 11.82; found C 57.44, H 3.68, N 11.51.
62.98, H 3.83, N 13.00.
Reaction of 1a with 2b: A mixture of 1a (2.53 g, 10.0 mmol), methyl
2-pyridylacetate (2b; 1.77 g, 10.0 mmol), and potassium carbonate
(3.44 g, 20.0 mmol) in DMSO (30 mL) was stirred for 2 h at room
temperature. This mixture was stirred and heated for 30 min at 50–
60 °C. The reaction mixture was poured into ice water (200 mL).
The precipitate that appeared was collected by filtration, washed
with water, and recrystallized from MeOH/toluene (5:1) to give yel-
low crystals of 4c (1.61 g, 4.7 mmol, 47% yield). This filtrate was
acidified with 10% hydrochloric chloride solution to give a red
brown caramel oil, which was crystallized by treatment with
MeOH. The crystallized products were collected by filtration to
give 5a and 6a (1.71 g, 4.4 mmol, 44% yield) as red crystals.
4-Imino-2-methylsulfanyl-3-tolylsulfonyl-4H-quinolizine-1-carboni-
trile (3b): This compound (1.31 g, 4.1 mmol) was prepared in 81%
yield from 1b (1.44 g, 5.0 mmol) and 2a (0.62 g, 5.0 mmol) in a
manner similar to that described for the synthesis of 3a. An analyti-
cal sample was recrystallized from DMF to give orange needles.
M.p. 178–182 °C. IR (KBr): ν = 3326 (NH), 2208 (CN), 1607, 1554,
˜
1505 1452 cm–1. UV (EtOH): λ (logε) = 384.5 (3.84), 279.0 (3.97)
nm. Fluorescence (solid): λEx = 333 nm; λEm = 552 nm; RI = 0.09.
Fluorescence (CH2Cl2): λEx = 262 nm; λEm = 522 nm; RI = 0.36.
1H NMR (300 MHz, CDCl3): δ = 2.29 (s, 3 H, SMe), 2.42 (s, 3 H,
Me), 7.17–7.23 (m, 1 H, 7-H), 7.30 (m, 2 H, phenyl-H), 7.81 (m, 1
H, 8-H), 7.82–7.88 (m, 2 H, phenyl-H), 7.88 (d, J = 8.3 Hz, 1 H,
Methyl 4-Imino-3-phenylsulfonyl-4H-quinolizine-1-carboxylate (4c):
M.p. 203–205 °C. IR (KBr): ν = 3336 (C=NH), 1702 (CO), 1617,
˜
1492, 1295, 1140, 579 cm–1. UV (EtOH): λ (logε) = 437.0 (3.39),
364.0 (3.44), 272.0 (3.55) nm. Fluorescence (solid): λEx = 342 nm;
λEm = 540 nm; RI = 1.46. Fluorescence (CH2Cl2): λEx = 283 nm;
1
λEm = 507 nm; RI = 0.40. H NMR (300 MHz, CDCl3): δ = 3.89
6-H), 9.64 (d, J = 7.4 Hz, 1 H, 9-H), 10.11 (s, 1 H, N-H) ppm. 13
C
(s, 3 H, OMe), 7.19 (m, 1 H, 7-H), 7.48–7.60 (m, 3 H, phenyl-H),
7.80 (m, 1 H, 8-H), 7.98 (m, 2 H, phenyl-H), 8.64 (br. s, 1 H, NH),
8.86 (s, 1 H, 2-H), 9.31 (d, J = 10.0 Hz, 1 H, 6-H), 9.68 (d, J =
7.8 Hz, 1 H, 9-H) ppm. 13C NMR (100 MHz, CDCl3): δ = 51.83,
97.24, 112.69, 117.10, 123.98, 127.09, 129.24, 131.05, 133.30,
137.68, 139.50, 140.78, 147.90, 151.62, 165.12 ppm. MS: m/z (%) =
343 (10) [M + 1]+, 342 (50) [M]+, 277 (100), 201 (22), 169 (25), 142
(11), 141(12). C17H14N2O4S (342.37): calcd. C 59.64, H 4.12, N
8.18; found C 59.77: H 4.04, N 8.22.
NMR (100 MHz, CDCl3): δ = 19.75, 21.60, 85.64, 116.11, 116.63,
117.27, 122.44, 127.11, 129.23, 131.92, 138.84, 140.10, 144.07,
147.43, 150.53, 151.46 ppm. MS: m/z (%) = 370 (4) [M + 1]+, 369
(69) [M]+, 368 (15), 305 (28), 304 (100), 214 (26), 167 (51), 127 (33).
C18H15N3O2S2 (369.0606): calcd. C 58.52, H 4.09, N 11.37; found
C 58.51, H 4.05, N 11.45.
4-Imino-3-phenylsulfonyl-4H-quinolizine-1-carbonitrile (4a): A solu-
tion of 3a (0.36 g, 1.0 mmol) in MeOH (100 mL) was heated at
reflux for 5 h. After removal of the solvent, the residue was washed
with MeOH (10 mL) to give orange crystals (0.31 g, 100% yield).
An analytical sample was recrystallized from MeOH/toluene (5:1)
Methyl (2Z,3E)-4-Cyano-3-methylsulfanyl-4-phenylsulfonyl-2-(1H-
pyrid-2-ylidene)butenoate (5a and 6a): M.p. 125–128 °C. IR (KBr):
1
ν = 2202 (CN), 1637 (CO), 1591, 1509 cm–1. H NMR (300 MHz,
˜
to give orange leaflets. M.p. 208–209 °C. IR (KBr): ν = 3337
˜
(C=NH), 2210 (CN), 1608, 1500, 1298, 1099, 583 cm–1. UV
(EtOH): λ (logε) = 385.5 (3.35), 315.5 (3.09), 282.0 (3.41) nm. Fluo-
rescence (solid): λEx = 339 nm; λEm = 546 nm; RI = 0.09. Fluores-
cence (CH2Cl2): λEx = 262 nm; λEm = 520 nm; RI = 0.31. 1H NMR
(300 MHz, CDCl3): δ = 7.54 (m, 1 H, 7-H), 7.54–7.62 (m, 2 H,
phenyl-H), 7.85 (m, 1 H, 8-H), 7.87–7.95 (m, 2 H, phenyl-H), 7.93
(d, J = 7.0 Hz, 1 H, 6-H), 8.27 (s, 1 H, 2-H), 8.81 (br. s, 1 H, N-
H), 9.62 (d, J = 7.7 Hz, 1 H, 9-H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 80.17, 114.71, 116.73, 117.58, 123.18, 127.02, 127.14,
129.39, 131.35, 133.67, 139.16, 140.17, 148.16, 150.41 ppm. MS:
m/z (%) = 310 (5) [M + 1]+, 309 (23) [M]+, 245 (20), 244 (100), 168
(37), 167 (42), 141 (16), 114 (13). C16H11N3O2S (309.3436): calcd.
C 62.12, H 3.58, N 13.58; found C 62.13, H 3.55, N 13.56.
CDCl3): δ = 2.14 (s, 3 H, SMe), 3.39 (s, 3H/2, OMe2), 3.51 (s. 3H/
2, OMe2), 6.42–6.61 (m, 2 H, pyridyl-H), 7.15–7.78 (m, 6 H,
phenyl-H, pyridyl-H), 8.09 (m, 1 H, pyridyl-H), 14.20 (br. s, 1 H,
NH) ppm. 13C NMR (100 MHz, CDCl3): δ = 15.18, 16.32, 50.75,
51.06, 81.34, 110.78, 110.97, 111.50, 114.07, 114.71, 117.72, 118.60,
127.64, 127.95, 128.76, 128.95, 129.22, 133.15, 133.41, 133.93,
138.16, 139.16, 139.85, 140.78, 150.79, 150.95, 166.48, 166.89,
173.75, 175.65 ppm. HRMS: calcd. for C18H16N2O4S2 388.0551;
found 388.0559. C18H16N2O4S2 (388.4627): calcd. C 55.65, H 4.15,
N 7.21; found C 55.70, H 4.04, N 6.96.
Reaction of 1b with 2b: Compound 4d (0.83 g, 2.1 mmol) was syn-
thesized in 41% yield from 2b (1.51 g, 10.0 mmol) and 1b (1.98 g,
5.0 mmol) in a manner similar to that described for the preparation
4-Imino-3-tolylsulfonyl-4H-quinolizine-1-carbonitrile (4b): This of 4c. An analytical sample was recrystallized from MeOH to give
compound (0.32 g, 1.0 mmol) was prepared in 100% yield from 3b yellow needles. Compounds 5b and 6b (0.39 g, 1.0 mmol) were syn-
Eur. J. Org. Chem. 2009, 5847–5853
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5851

Y. Tominaga et al.
FULL PAPER
thesized in 19% yield in a manner similar to that described for the
preparation of 5a and 6a. An analytical sample was recrystallized
from MeOH to give red crystals.
CDCl3): δ = 0.90–1.17 (m, J = 7.1 Hz, 3 H, O-CH2-CH3), 2.15 (s,
3 H, SMe), 3.60–4.16 (m, 2 H, O-CH2-), 6.40–6.70 (m, 1 H, pyridyl-
H), 7.20–7.80 (m, 7 H, phenyl-H, pyridyl-H), 8.12 (d, J = 10.2 Hz,
1 H, pyridyl-H), 14.02 (br. s, 1 H, NH) ppm. 13C NMR (100 MHz,
CDCl3): δ = 14.24, 15.14, 16.28, 59.66, 81.43, 110.62, 110.78,
111.77, 114.15, 114.62, 117.81, 118.76, 127.69, 127.97, 128.74,
129.01, 133.16, 133.31, 133.92, 137.97, 139.94, 140.85, 150.92,
166.24, 145.00, 166.51, 173.84, 175.86 ppm. MS: m/z (%) = 403 (5)
[M + 1]+, 402 (19) [M]+, 261 (100), 260 (55), 215 (63), 77 (34).
C19H18N2O4S2 (402.4893): calcd. C 56.70, H 4.51, N 6.96; found C
56.69, H 4.54, N 6.86.
Methyl 4-Imino-3-tolylsulfonyl-4H-quinolizine-1-carboxylate (4d):
M.p. 216–218 °C. IR (KBr): ν = 3343 (NH), 1691 (CO), 1618, 1492,
˜
1141, 781 cm–1. UV (EtOH): λ (logε) = 436.0 (3.99), 365.0 (4.03),
270.5 (4.19) nm. Fluorescence (solid): λEx = 340 nm; λEm = 533 nm,
RI = 1.17. Fluorescence (CH2Cl2): λEx = 280 nm; λEm = 511 nm;
RI = 0.47. 1H NMR (300 MHz, CDCl3): δ = 2.39 (s, 3 H, Me),
3.89 (s, 3 H, OMe), 7.18 (m, 1 H, 7-H), 7.30 (d, J = 8.4 Hz, 2 H,
phenyl-H), 7.80 (m, 1 H, 8-H), 7.84 (d, J = 8.4 Hz, 2 H, phenyl-
H), 8.60 (br. s, 1 H, NH), 8.85 (s, 1 H, 2-H), 9.30 (d, J = 9.0 Hz, 1
H, 6-H), 9.67 (d, J = 7.8 Hz, 1 H, 9-H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 21.55, 51.79, 97.15, 113.19, 116.98, 123.94, 127.17,
129.85, 130.94, 137.51, 137.74, 139.21, 144.29, 147.81, 151.62,
165.15 ppm. MS: m/z (%) = 357 (11) [M + 1]+, 356 (51) [M]+, 291
(100), 201 (32), 169 (46). C18H16N2O4S2 (388.46): calcd. C 60.66,
H 4.53, N 7.86; found C 60.75, H 4.35, N 7.88.
Reaction of 1b with 2c: Compound 4f (0.89 g, 2.4 mmol) was syn-
thesized in 48% yield from 2c (1.65 g, 10.0 mmol) and 1b (1.44 g,
5.0 mmol) in a manner similar to that described for the preparation
of 4c. An analytical sample was recrystallized from EtOH to give
yellow needles. Compounds 5d and 6d (0.92 g, 2.2 mmol) was syn-
thesized in 44% yield in manner similar to that described for the
preparation of 5a and 6a. An analytical sample was recrystallized
from MeOH to give red crystals.
Methyl
(2Z,3E)-4-Cyano-3-methylsulfanyl-4-tolylsulfonyl-2-(1H-
pyrid-2-ylidene)butenoate (5b and 6b): M.p. 165–168 °C. IR (KBr):
˜
Ethyl 4-Imino-3-tolylsulfonyl-4H-quinolizine-1-carboxylate (4f):
ν = 2201 (CN), 1618, 1590, 1283 1151, 584 cm–1. UV (EtOH): λ
M.p. 177–178 °C. IR (KBr): ν = 3302 (NH), 1761 (CO), 1704 (CO),
˜
(logε) = 393.0 (3.59), 302.5 (4.09) nm. 1H NMR (300 MHz,
CDCl3): δ = 2.14 (s, 3 H, Me), 2.38 (s, 3H/2, SMe), 2.48 (s, 3H/2,
SMe), 3.41 (s 3H/2, OMe), 3.56 (s, 3H/2, OMe), 6.40–6.60 (m, 1
H, pyridyl-H), 7.19 (m, 1 H, pyridyl-H), 7.38 (m, 2 H, phenyl-H),
7.48 (m, 2 H, phenyl-H), 7.61 (d, J = 7.8 Hz, 1 H, pyridyl-H), 7.97
(d, J = 8.1 Hz, 1 H, pyridyl-H), 14.00 (br. s, 1 H, NH) ppm. 13C
NMR (100 MHz, CDCl3): δ = 15.14, 16.27, 21.54, 21.73, 50.72,
51.10, 81.40, 110.57, 110.85, 111.94, 114.12, 114.73, 117.80, 118.77,
127.77, 128.10, 129.35, 129.58, 133.36, 133.93, 136.95, 137.82,
137.97, 139.06, 144.22, 145.01, 150.86, 151.00, 166.59, 166.97,
173.04, 174.86 ppm. MS: m/z (%) = 403 (5) [M + 1]+, 402 (21)
[M]+, 247 (100), 215 (32), 200 (83), 168 (25), 91 (26). C19H18N2O4S2
(402.4893): calcd. C 56.70, H 4.51, N 6.96; found C 56.71, H 4.48,
N 6.79.
1615, 1513 cm–1. UV (EtOH): λ (logε) = 435.5 (3.12), 364.5 (3.17),
271.5 (3.34) nm. Fluorescence (solid): λEx = 332 nm; λEm = 536 nm,
RI = 0.62. Fluorescence (CH2Cl2): λEx = 284 nm; λEm = 519 nm;
1
RI = 0.25. H NMR (300 MHz, CDCl3): δ = 1.42 (t, J = 7.1 Hz,
3 H, O-CH2-CH3), 2.39 (s, 3 H, Me), 4.36 (q, J = 7.1 Hz, 2 H, O-
CH2-), 7.17 (m, 1 H, 7-H), 7.30 (d, J = 7.9 Hz, 2 H, phenyl-H),
7.77 (m, 1 H, 8-H), 7.84 (d, J = 7.9 Hz, 2 H, phenyl-H), 8.56 (br.
s, 1 H, NH), 8.84 (s, 1 H, 2-H), 9.31 (d, J = 9.0 Hz, 1 H, 6-H),
9.66 (d, J = 6.6 Hz, 1 H, 9-H) ppm. 13C NMR (100 MHz, CDCl3):
δ = 14.48, 21.56, 60.73, 97.52, 113.09, 116.91, 124.00, 127.19,
129.85, 130.94, 137.38, 137.73, 139.16, 144.28, 147.82, 151.66,
164.76 ppm. MS: m/z (%) = 371 (9) [M + 1]+, 370 (40) [M]+, 306
(23), 305 (100), 277 (28), 225 (25). C19H18N2O4S (370.4233): calcd.
C 61.61, H 4.90, N 7.56; found C 61.63, H 4.93, N 7.42.
Reaction of 1a with 2c: Compound 4e (0.33 g, 0.9 mmol) was syn-
thesized in 46% yield from 2c (0.33 g, 2.0 mmol) and 1a (0.86 g,
3.0 mmol) in a manner similar to that described for the preparation
of 4c. An analytical sample was recrystallized from EtOH to give
yellow needles. Compounds 5c and 6c (0.35 g, 0.9 mmol) were syn-
thesized in 44% yield in a manner similar to that described for the
preparation of 5a and 6a. An analytical sample was recrystallized
from MeOH to give red crystals.
Ethyl
(2Z,3E)-4-Cyano-3-methylsulfanyl-4-tolylsulfonyl-2-(1H-
pyrid-2-ylidene)butenoate (5d and 6d): M.p. 132–135 °C. IR (KBr):
ν = 2207 (CN), 1650 (CO), 1615, 1585, 1267, 1150, 588 cm–1. UV
˜
(EtOH): λ (logε) = 392.0 (3.69), 304.0 (4.19) nm. 1H NMR
(300 MHz, CDCl3): δ = 0.98 (t, J = 7.1 Hz, 3H/2, O-CH2-CH3),
1.10 (t, J = 7.1 Hz, 3H/2, O-CH2-CH3), 2.15 (s, 3 H, Me), 2.39 (s,
3 H, Me), 3.70 (m, 2H/2, O-CH2-), 4.0 (m, 2H/2, O-CH2-), 6.43–
6.65 (m, 1 H, pyridyl-H), 7.20 (m, 1 H, pyridyl-H), 7.37 (m, 2 H,
phenyl-H), 7.46 (m, 2 H, phenyl-H), 7.62 (m, 1 H, pyridyl-H), 7.97
(m, 1 H, pyridyl-H), 14.00 (br. s, 1 H, NH) ppm. 13C NMR
(100 MHz, CDCl3): δ = 13.91, 14.12, 15.04, 16.20, 21.45, 21.60,
59.54, 61.83, 81.32, 110.46, 110.75, 111.94, 114.12, 114.67, 117.70,
118.62, 126.82, 127.67, 127.98, 129.29, 129.56, 133.40, 133.95,
136.42, 136.94, 137.84, 138.96, 144.18, 145.00, 150.85, 166.22,
166.45, 173.29, 174.31 ppm. MS: m/z (%) = 416 (3) [M]+, 260 (100),
215 (72), 214 (38), 188 (20), 139 (30), 91 (27). C20H20N2O4S2
(416.5159): calcd. C 57.67, H 4.84, N 6.73; found C 57.34, H 4.82,
N 6.59.
Ethyl 4-Imino-3-phenylsulfonyl-4H-quinolizine-1-carboxylate (4e):
M.p. 152–155 °C. IR (KBr): ν = 3356 (NH), 1694 (CO), 1639, 1618,
˜
1489, 578 cm–1. UV (EtOH): λ (logε) = 437.0 (4.03), 364.5 (4.06),
272.0 (4.19) nm. Fluorescence (solid): λEx = 339 nm; λEm = 528 nm;
RI = 1.44. Fluorescence (CH2Cl2): λEx = 284 nm; λEm = 511 nm;
1
RI = 0.47. H NMR (300 MHz, CDCl3): δ = 1.43 (t, J = 7.1 Hz,
3 H, O-CH2-CH3), 4.36 (q, J = 7.1 Hz, 2 H, O-CH2-), 7.17 (m, 1
H, 7-H), 7.45–7.62 (m, 3 H, phenyl-H), 7.79 (m, 1 H, 8-H), 7.96
(m, 2 H, phenyl-H), 8.61 (br. s, 1 H, NH), 8.86 (s, 1 H, 2-H), 9.32
(d, J = 9.0 Hz, 1 H, 6-H), 9.67 (d, J = 6.9 Hz, 1 H, 9-H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 14.47, 60.76, 97.60, 112.60, 117.04,
124.03, 127.08, 129.21, 130.99, 133.27, 137.54, 139.43, 140.75,
147.88, 151.64, 164.70 ppm. MS: m/z (%) = 357 (14) [M + 1]+, 356
(65) [M]+, 292 (20), 291 (95), 133 (100), 105 (45). C18H16N2O4S
(356.3967): calcd. C 60.66, H 4.53, N 7.86; found C 60.54, H 4.38,
N 7.89.
X-ray Crystallographic Studies: The reflection data were collected
at 23 Ϯ1 °C with a Rigaku Mercury area detector with graphite
monochromated Mo-Kα radiation. All calculations were performed
by using the CrystalStructure crystallographic software package.[13]
CCDC-736921 (for 4a), -736922 (for 4c), and -725724 (for 5b) con-
Ethyl
(2Z,3E)-4-Cyano-3-methylsulfanyl-4-phenylsulfonyl-2-(1H- tain the supplementary crystallographic data for this paper. These
pyrid-2-ylidene)butenoate (5c and 6c): M.p. 143–146 °C. IR (KBr): data can be obtained free of charge from The Cambridge Crystallo-
1
ν = 2204 (CN), 1638 (CO), 1582, 1277 cm–1. H NMR (300 MHz, graphic Data Centre via www.ccdc.cam.au.uk/data_request/cif.
˜
5852
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 5847–5853

Synthesis of 4H-Quinolizine Derivatives by Sulfonyl Ketene Dithioacetals
[3] a) H. Awaya, C. Maseda, Y. Tominaga, R. Natsuki, Y. Mat-
Crystal Data for 4a: This crystal was obtained by recrystallization
from MeOH/acetonitrile (1:1) to give orange prisms of formula
C16H11N3O2S and having approximate dimensions of
0.50ϫ0.40ϫ0.15 mm. This crystal was mounted on a glass fiber.
Crystal data formula weight: 309.34; crystal color, habit: orange,
prisms; crystal system: triclinic; lattice type: primitive; lattice pa-
suda, G. Kobayashi, Chem. Pharm. Bull. 1974, 22, 1424–1426;
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rameters: a = 5.9847(10) Å, b = 8.3812(14) Å, c = 14.2469(15) Å,
3
¯
β = 80.363(15)°, V = 703.50(18) Å ; space group: P1 (#2); Z value:
2; Dcalcd.: 1.460 gcm–3; F(000) = 320.00; µ(Mo-Kα) = 2.406 cm–1.
Crystal Data for 4c: This crystal was obtained by recrystallization
from MeOH/acetonitrile (1:1) to give yellow prisms of formula
C17H14N2O4S and having approximate dimensions of
0.40ϫ0.30ϫ0.20 mm. This crystal was mounted on a glass fiber.
Crystal data formula weight: 342.37; crystal color, habit: yellow,
prisms; crystal system: triclinic; lattice type: primitive; lattice pa-
rameters: a = 7.4827(10) Å, b = 10.6167(10) Å, c = 11.1355(10) Å,
3
¯
β = 74.953(8)°, V = 781.977(13) Å ; space group: P1 (#2); Z value:
2; Dcalcd.: 1.454 gcm–3; F(000) = 356.00; µ(Mo-Kα) = 2.314 cm–1.
Crystal Data 5b: This crystal was obtained by recrystallization from
MeOH to give orange prisms of formula C19H18N2O4S2 and having
approximate dimensions of 0.40ϫ0.20ϫ0.20 mm. This crystal was
mounted on a glass fiber. Crystal data formula weight: 402.48;
crystal color, habit: orange, prisms; crystal system: monoclinic; lat-
tice type: primitive; lattice parameter: a = 10.3450(5) Å, b =
11.8475(5) Å,
c = 16.1782(10) Å, β = 101.7174(10)°, V =
[9] Y. Tominaga, “Product Class Cyclazines” in “Science of Syn-
thesis” (Ed.: S. M. Weinreb), Thieme, Stuttgart, 2004, vol. 17,
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1941.52(17) Å3; space group: P21/n (#14); Z value: 4; Dcalcd.
1.377 gcm–3; F(000) = 840.00; µ(Mo-Kα) = 3.012 cm–1.
:
[10] M. Hagimori, N. Mizuyama, Y. Tominaga, ARKIVOC 2008,
13, 16–27.
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[13] a) CrystalStructure 3.8, Crystal Structure Analysis Package,
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Received: July 15, 2009
Published Online: September 30, 2009
Eur. J. Org. Chem. 2009, 5847–5853
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5853