Modified riemschneider reaction of 3-thiocyanatoquinolinediones

Article abstract of DOI:10.1002/hlca.201200049

The Riemschneider reaction of 3-thiocyanatoquinoline-2,4(1H,3H)-diones with conc. H₂SO₄ was investigated. Using different reaction conditions, 13 types of reaction products were isolated. Compounds bearing a Me, Et, or Bu group at C(3) afforded mainly [1,3]thiazolo[5,4-c]quinoline-2,4- diones and 1,9b-dihydro-9b-hydroxythiazolo[5,4-c]quinoline-2,4-diones. In the case of the 3-Bu derivatives of the starting compounds, C-debutylation was also observed. If a Bn group is present at C(3), rapid C-debenzylation of the starting thiocyanates occurred, yielding [1,3]oxathiolo[4,5-c]quinoline-2,4- diones, and mixtures of mono-, di-, and trisulfides derived from 4-hydroxy-3-sulfanylquinoline-2-ones. The reaction mechanism of all of the transformations is discussed. All new compounds were characterized by IR, ¹H- and ¹³C-NMR, and EI and ESI mass spectra, and in some cases, ¹⁵N-NMR spectra were also used to characterize new compounds. Copyright

Full text of DOI:10.1002/hlca.201200049

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Helvetica Chimica Acta – Vol. 95 (2012)
Modified Riemschneider Reaction of 3-Thiocyanatoquinolinediones
by Ondrˇej Rudolfa), Vladimꢀr Mrkvicˇkaa), Antonꢀn Lycˇkab), Michal Rouchala), and Antonꢀn Kla´sek*a)
a) Department of Chemistry, Faculty of Technology, Tomas Bata University, CZ-76272 Zlin
(e-mail: klasek@ft.utb.cz)
b) Research Institute for Organic Syntheses (VUOS), Rybitvꢀ 296, CZ-53354 Pardubice 20
The Riemschneider reaction of 3-thiocyanatoquinoline-2,4(1H,3H)-diones with conc. H2SO4 was
investigated. Using different reaction conditions, 13 types of reaction products were isolated. Compounds
bearing a Me, Et, or Bu group at C(3) afforded mainly [1,3]thiazolo[5,4-c]quinoline-2,4-diones and 1,9b-
dihydro-9b-hydroxythiazolo[5,4-c]quinoline-2,4-diones. In the case of the 3-Bu derivatives of the starting
compounds, C-debutylation was also observed. If a Bn group is present at C(3), rapid C-debenzylation of
the starting thiocyanates occurred, yielding [1,3]oxathiolo[4,5-c]quinoline-2,4-diones, and mixtures of
mono-, di-, and trisulfides derived from 4-hydroxy-3-sulfanylquinoline-2-ones. The reaction mechanism
of all of the transformations is discussed. All new compounds were characterized by IR, 1H- and
13C-NMR, and EI and ESI mass spectra, and in some cases, 15N-NMR spectra were also used to
characterize new compounds.
1. Introduction. – One of the most important families of naturally occurring sulfur
compounds is the glucosinolate family, which occurs in cruciferous vegetables. By
enzymatic hydrolysis, this class of compounds affords glucose, HSOꢀ4 ions, and aglycone
derivatives, as well as isothiocyanates, thiocyanates, and nitriles [1].
Some aglycones such as thiocyanates act as chemoprotective agents against
chemically induced carcinogenesis by blocking the initiation of tumors in a variety of
rodent tissues [2]. Thiocyanates are also important starting compounds for the
synthesis of various heterocyclic compounds that possess important biological activities
[3][4].
Several methods are known for the introduction of S functionalities into molecules
[5][6]. We found that 3-chloro- and 3-bromoquinoline-2,4-diones react with some S
reagents (NaSH, AcSH, KSCN, thiourea) to give 4-hydroxy-1H-quinoline-2-ones 1 [7].
In this reaction, the 3-halogenoquinoline-2,4-diones, which bear a ꢁpositive chargedꢂ
halogen atom, exhibit a strong oxidative effect on all of the compounds that have a free
SH group. Therefore, the preparation of their 3-sulfanyl or 3-thiocyanato analogs by a
nucleophilic substitution route is impossible. However, we have prepared 3-thiocya-
natoquinoline-2,4-diones 2 via the reaction of 4-hydroxy-1H-quinoline-2-ones 1 with
an in situ prepared (SCN)2 in AcOH [7].
Although the non-enolizable a-thiocyanato derivatives of b-dicarbonyl compounds
should be relatively stable [6], compounds 2 are only stable in the crystalline form. In
protic solvents, they readily undergo nucleophilic attack by H2O on the S-atom to form
the starting 4-hydroxy-1H-quinoline-2-ones 1 [7]. This reaction is analogous to the
reactions of a-thiocyanato b-diketones with aqueous alkali or with NH4OH [8][9]. We
ꢃ 2012 Verlag Helvetica Chimica Acta AG, Zꢄrich

Helvetica Chimica Acta – Vol. 95 (2012)
1353
also found that the thiocyanato (SCN) group can be selectively transferred from 2 to
some nucleophiles (amines, activated aromatic compounds, thioles, Wittig reagents)
[10].
The SCN group can be transformed to the thiocarbamate group via the
Riemschneider reaction by treatment with conc. H2SO4 [11][12]. The reaction of a-
thiocyanato ketones with H2SO4, most frequently carried out in the presence of AcOH,
usually does not stop at the formation of the carbamates but continues through a
dehydration process to form thiazol-2(3H)-ones [13 – 15].
In a previous report [16], we described the reaction of 3-thiocyanatoquinoline-2,4-
diones 2 in conc. H2SO4, or in its mixture with AcOH, to give a mixture of
hydrolytically unstable thiocarbamates
3
and [1,3]thiazolo[5,4-c]quinoline-
2,4(3aH,5H)-diones 4 (Scheme 1). Compounds 3 were cyclodehydrated to 4 by
treatment with P2O5 in AcOH. In two cases, the C(3)-dealkylated products, which were
identified as thiazoloquinolinediones 5, were also isolated. The extent of this reaction
substantially increases, when excess of P2O5 was added to the mixture.
Scheme 1
Therefore, we decided to study the modified Riemschneider reaction in detail under
different reaction conditions and using compounds that bear varying substituents at
C(3). Owing to the high reactivity of quinoline-2,4-dione derivatives and our
experiences in this area, we anticipated the isolation of novel compounds in this
process.
2. Results and Discussion. – To determine the influence of the R2 substituent (cf.
Scheme 1) on the transformation of compounds 2, we chose the Me, Et, Bu, and Bn
groups, and H, Me, and Ph were selected as R1. The starting compounds 2 were
prepared by the reaction of 4-hydroxy-1H-quinolin-2-ones 1 with (SCN)2 according to
[7][16]. By this process, seven novel compounds were prepared. Although two new
methods for the a-thiocyanation of ketones and b-dicarbonyl compounds were recently
described [17][18], we were unable to use them, because 4-hydroxy-1H-quinolin-2-
ones 1 were insoluble in the procedureꢂs requisite solvents. The starting compound 1l
was almost insoluble even in AcOH. Thus, we carried out the thiocyanation of 1l in a
DMF solution. The 1H- and 13C-NMR spectra of the new compounds 2 are presented in
Table 1.
Because the composition of the mixture for the reaction of thiocyanates 2
substantially influences the ratio of the reaction products [16], we carried out the
reaction under three different reaction conditions. In the first method, P2O5 was added

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to the solution of 2 in a 1:9 mixture AcOH conc. H2SO4 (Method A), in the second
one, P2O5 was added to the solution of 2 in conc. H2SO4 (Method B), and in the third
method (Method C), AlCl3 was added to the solution of 2 in conc. H2SO4. The results
of these experiments are compiled in Scheme 2 and Table 2.
Scheme 2
To our surprise, thiocarbamates 3 were isolated in only four cases, i.e. 3a, 3b, 3c, and
3g. Thiazoloquinolinediones 4 were found as products from all of the starting

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Helvetica Chimica Acta – Vol. 95 (2012)
Table 2. Results of Modified Riemschneider Reaction of 3-Thiocyanatoquinoline-2,4-diones 2
Entry
2
a
R1
H
R2
Methoda)
Time [min]
Product(s) (Yield [%])b)c)
1
2
3
Me
A
B
C*
60
30
50
6a (46)
3a (35), 4a (7)
1a (52)b), 6a (8)
4
5
6
b
c
H
H
Et
A
B
C
180
60
60
4b (7), 6b (40)
3b (42), 4b (18)
1b (26), 4b (18)
7
8
9
10
11
12
Bu
A
A
A
B*
B*
C
10
30
21 h
30
40
3c (52), 4c (10)
1c (33), 4c (14)
5c (43)
1c (30)
1c (47)
21 h
5c (34)
13
14
15
16
d
H
Bn
A
B
B*
C*
180
30
12d (48), Md (4)d)
11d (6), 12d (5), Mdd) (55)
Mdd) (22)
30
Mdd) (35)
17
18
19
e
f
Me
Me
Me
Me
Et
A
B*
C*
150
60
60
1e (5), 4e (18), 6e (63)
1e (27), 4e (8), 8e (29)
1e (24), 4e (4), 6e (3), 8e (23)
20
21
22
A
B*
C
17 h
40
60
4f (41), 6f (16), 7f (4)
1f (13), 4f (53)
1f (5), 4f (42)
23
24
25
26
g
Bu
A
B
B*
C*
180
60
90
5g (63)
1g (14), 4g (21), 5g (1)
1g (10), 4g (18), 5g (3), 7g (4), 8g (18)
1g (38), 4g (4), 8g (10)
90
27
28
29
h
i
Me
Ph
Ph
Ph
Bn
Me
Et
A
B
C
60
30
60
Mhd) (33)
Mhd) (46)
Mhd) (33)
30
31
32
A
B*
C*
120
60
60
1i (7), 4i (69)
1i (36), 4i (4), 8i (25)
1i (59), 4i (2), 8i (22)
33
34
35
j
A
B*
C*
60
40
30
1j (7), 4j (61), 6j (8)
1j (30), 4j (12), 7j (7)
1j (30), 4j (35)
36
37
38
39
40
k
Bu
A
A
A*
B
60
21 h
45
25
45
1k (22), 4k (54)
1k (6), 4k (15), 5k (34)
1k (14), 4k (23), 8k (26), 9k (4)
3k (40), 4k (23)
C
3k (23), 4k (51)
41
42
43
44
45
l
Ph
Bn
A
A*
B
B*
C*
45
45
45
30
60
11l (9)b, 12l (7), Mld) (30)
Mld) (44)
11l (4), 12l (26), Mld) (25)
11l (3), Mld) (32)
11l (5), Mld) (42)
a) Methods: A: H2SO4 96%/AcOH, 9 : 1, P2O5; B: H2SO4 96%, P2O5; C: H2SO4 96%, AlCl3. In
experiments designated with asterisk, for alkalization of the crude mixture, NH4OH was used. b) All
isolated compounds 1 and 7 were identical to authentic samples. c) In most cases, elemental sulfur was
also isolated. d) Mixtures of compounds 13, 14, and 15, yields were calculated to pure compound 14.

Helvetica Chimica Acta – Vol. 95 (2012)
1357
compounds 2 with the exception of 2d, 2h, and 2l, which bear a Bn group at C(3). In the
reactions in which 4a, 4b, 4e, 4f, and 4j were formed, their hydrated analogs 6a, 6b, 6e,
6f, and 6j, none of which has been reported previously, arose from their corresponding
starting materials. The structures of studied compounds were based on standard 1D 1H-
and 13C-NMR spectra, and on several 2D experiments (gradient-selected (gs)-COSY,
gs-HMQC, gs-HMBC). The presence of one sp3 C-atom (C(3)) and 13C signals
resonating at 194 ppm (C(4)) was a typical feature of compounds 3, whereas
compounds 4 showed one sp3 C-atom resonance (C(3a)), and compounds 6 displayed
two sp3 C-atom resonances (C(3a) and C(9b); cf. Tables 3 – 5).
Table 3. 1H- and 13C-NMR Data (CDCl3) of Compounds 3 (d in ppm)
Position
3a
3b
3c
3k
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
2
3
4
4a
5
6
7
8
8a
–
–
–
–
7.82
7.15
7.66
7.18
–
171.7
61.9
–
–
–
–
7.80
7.14
7.64
7.16
–
171.0
66.3
–
–
–
–
7.80
7.13
7.64
7.16
–
171.1
65.5
193.7
119.0
126.8 7.98
122.4 7.24
136.0 7.56
116.4 6.38
–
–
–
–
170.8
65.8
193.8
117.8
127.3
122.5
136.1
116.4
141.6
193.7
119.0
126.8
122.4
136.0
116.4
141.6
193.2
119.8
127.2
123.0
136.0
116.6
143.5
141.6
–
Substituent at N(1)
1
11.01
–
–
–
–
11.05
–
–
–
–
11.04
–
–
–
–
–
138.0
2,6
3,5
4
–
–
–
–
–
–
–
–
–
7.42, 7.16 130.4, 128.6
7.67, 7.42 130.3, 129.4
7.56
128.9
Substituent at C(3)
1
1.46
21.7
–
1.92
1.87
0.83
29.8
9.0
1.86
1.82
1.22
1.12
1.19
0.78
36.0 1.99
36.2
26.3
2
–
26.2 1.39
1.24
22.1 1.24
13.6 1.07
3
4
–
–
–
–
–
–
–
–
22.1
13.6
SCONH2
7.90, 7.41 166.4
7.86, 7.39 166.4
7.82, 7.38 166.4 7.97, 7.45 166.5
Unfortunately, we have found that the dealkylated products 5 were formed only in
cases in which the starting compounds contained a Bu group at C(3) (i.e., 5c, 5g, and
5k), and prolonged reaction times were employed (Table 2). In some cases,
nucleophilic substitution was found to proceed in thiocyanates 2, and small quantities
of known 3-hydroxyquinoline-2,4-diones 7f, 7g, and 7j were isolated.
In several cases, conc. NH4OH was used during the isolation of the reaction product
with the aim to basify the crude extract after the reaction (Methods A*, B*, and C*).
Under these conditions, side-products 8i, 8k and 9e, 9g, and 9k were isolated (Table 2).
We propose that compounds 8 and 9 arise from the nucleophilic ring opening of the
thiazolones 4 with NH4OH and subsequent desulfuration (Scheme 3). The presence of
the CONH2 group at the N-atom in compounds 8 implies that the C(O)ꢀS bond in

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Table 5. 1H- and 13C-NMR Data ((D6)DMSO) of Compounds 6 (d in ppm)
Position
6a
6b
6e
6f
6j
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
1
2
3a
4
5a
6
7
8
9
9a
9b
9.06
–
–
–
–
6.99
7.37
7.14
7.71
–
–
8.91a)
–
–
–
–
9.08b)
–
–
–
–
8.95c)
–
–
–
–
9.13
–
–
–
–
6.25
7.30
7.21
7.86
–
–
170.5
63.7
171.1
69.2
170.7
64.5
171.2
69.8
171.2
70.5
169.6
134.9
115.2
130.1
122.8
127.8
122.1
87.3
169.4
134.9
115.1
130.0
122.7
127.0
122.6
86.7
169.3
136.8
114.9
130.4
123.3
127.7
123.4
86.6
169.0
136.7
114.8
130.3
123.2
126.9
124.1
85.6
168.9
137.9
115.8
129.9
123.3
127.5
123.5
86.1
–
–
–
6.97
7.35
7.11
7.69
–
7.26
7.50
7.26
7.82
–
7.23
7.50
7.23
7.81
–
–
–
–
–
–
Substituent at N(1)
1
10.72
–
–
–
–
10.75c)
3.39
30.5
3.43
30.4
–
137.7
129.0
130.2
128.7
2,6
3,5
4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
7.35
7.65
7.56
Substituent at C(3a)
1
1.54
18.9
2.04
1.96
0.78
–
–
–
26.1
1.51
18.9
2.04
1.95
0.68
–
–
–
26.2
2.16
2.12
0.88
–
–
–
26.0
2
3
4
5
–
–
–
–
–
–
–
–
–
10.1
–
–
–
–
–
–
–
–
–
10.1
10.3
–
–
–
–
–
–
–
–
–
–
–
–
OH
7.00
7.08
7.07
7.22
7.25
a
b
c
1
1
) 1J (15N, 1H) ¼ 90.8. ) 1J (15N, H) ¼ 90.9. ) 1J (15N, H) ¼ 90.2.
compounds 4 must be primarily attacked during the formation of intermediate A. We
confirmed our assumption by carrying out the reactions of compounds 4e, 4g, 4i, and 4j
with NH4OH in EtOH (Method D), and these reactions yielded compounds 8e, 8g, 8j
and 9e, 9i, 9j, respectively. In all cases, elemental S arises simultaneously. The analogous
reaction proceeds also with 6e, but does not occur with compounds 5. The most
characteristic 13C resonance in compounds 9 was that of C(3), which reflected the
strong donor effect of the amino group at C(4) (Table 6). The presence of the
Scheme 3

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1361
NHCONH2 fragment in compounds 8g was clearly demonstrated by using 15N-NMR
spectra (Table 6). Surprisingly, the corresponding carbamate 10g was obtained after
recrystallization of 8g from BuOH. Compared with the NMR data of compound 8g, a
second set of Bu group signals appeared in the spectrum of compound 10g, and the
typical 13C resonance of the carbamate COO group (154.8 ppm) was observed
(Table 6).
The reaction of compounds 2 with the Bn group at C(3), i.e., 2d, 2h, and 2l,
proceeds differently. A minute quantity of compound 11l was obtained from the
reaction of 2l. In two cases, novel dealkylated compounds 12d and 12l were obtained.
The presence of an oxathiolone ring in these compounds indicated a rapid
debenzylation of compounds 2 under the formation of intermediate B, followed by
closure of the oxathiolone ring to give compounds 12 (Scheme 4). However,
compounds 12 behave unlike their aza analogs 5. Whereas compounds 5 did not react
with NH4OH, compounds 12d and 12l yielded (Method D) 4-hydroxyquinoline-2-ones
11d and 11l, respectively (Scheme 4). Compounds 12 were possibly transformed to
compounds 11 through intermediates C and their tautomers D.
Scheme 4
The main products of the reaction of 2d, 2h, and 2l are poorly soluble fractions
designated as Md, Mh, and Ml (Table 2). In both their 1H- and 13C-NMR spectra, the
signals corresponding to the Bn group are not present, i.e., the debenzylation of starting
compounds 2 took place during the formation of compounds 12. The molecular peak
corresponding to sulfides 13 appears in EI-MS of fractions M. However, the results of
elemental analyses are not in accord with those expected for structure 13. They show
considerable higher levels of S and more likely correspond to disulfides 14. Therefore,
we used ESI-MS, a process with milder conditions. The results of these recordings
provided evidence that fractions M are mixtures of sulfides 13, disulfides 14, and

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Helvetica Chimica Acta – Vol. 95 (2012)
trisulfides 15. However, the dominant compound in mixtures M was always disulfide 14.
The origin of this compound can be explained by the dehydrogenation of intermediate
C (Scheme 4). The formation of compounds 13 and 15 can be rationalized by the
disproportionation of disulfide 14. Another possibility is the formation of 15 by the
reaction of 14 with elemental S, which was isolated in most cases from the mixture, and
the formation of 13 by the reaction of disulfide 14 with 11, similar to that which was
described for the reaction of 11 with disulfides [19].
All of our attempts to isolate pure individual compounds from the mixtures M by
column chromatography failed. In particular, this failure was due to their poor
solubility and very similar chromatographic characteristics. Therefore, we tried to
separate the mixtures M by repeated fractional crystallization. By this method, albeit in
poor yields, pure compounds 13d, 13l, 14h, and 14l were obtained (see Table 7, Exper.
Part, for NMR data for these compounds).
3. Conclusions. – The the Riemschneider reaction of thiocyanates 2 under classical
conditions in H2SO4 or its mixture with AcOH provide only compounds 3 and 4 [16]. In
conclusion, we would like to emphasize that the addition of P2O5 or AlCl3 to the
mixture leads, according to presumption, to the formation of other new compounds,
mainly 6 (Table 2). In addition, compounds 8 and 9 can be obtained by modifying the
procedure treating the crude reaction product with NH4OH. The best results for these
experiments were obtained by Method A, where the smallest quantities of 1 as
degradation products were produced. Method C was found to be inconvenient in the
majority of cases. The exceptionally easy C-debenzylation of compounds 2 enabled the
desired preparation of novel [1,3]oxathiolo[4,5-c]quinoline-2,4-diones 12 by a simple
procedure. Because many biologically active compounds contain a S-atom [20][21],
compounds 12 could also be interesting structures to be studied in further
investigations.
This study was supported by the Ministry of Education, Youth and Sports of the Czech Republic
(Grant No. MSM 7088352101) and the internal grant of TBU in Zlꢀn (No. IGA/8/FT/11/D), funded from
ˇ
´
the resources of specific university research. The authors thank Mrs. H. Gerzova (Faculty of Technology,
Tomas Bata University in Zlꢀn) for technical help.
Experimental Part
1. General. TLC: Alugramꢅ-SIL-G/UV254 foils (Macherey-Nagel); elution with benzene/AcOEt 4 :1,
CHCl3/EtOH 9 :1 and/or 19 :1, CHCl3/AcOEt 7:3, and CHCl3/AcOH 9 :1. Column chromatography
(CC): silica gel (SiO2; Merck, grade 60, 70 – 230 mesh); elution with CHCl3, then CHCl3/EtOH 99 :1 !
8 :2, or benzene, and then benzene/AcOEt 99 :1 ! 8 :2. M.p.: Kofler block or Gallencamp apparatus. IR
Spectra: Nicolet iS10 spectrophotometer; KBr pellets; n in cmꢀ1. NMR Spectra: Bruker Avance
spectrometer at 500.13 (1H) and 125.76 MHz (13C), and Bruker Avance II 400 spectrometer at 400.13
(1H), 100.56 (13C), and 40.55 MHz (15N); (D6)DMSO soln.; d in ppm rel. to Me4Si as internal or 15N-
enriched MeNO2 as external (in a co-axial capillary) standard; J in Hz; manufacturerꢂs software for all
2D experiments (gradient-selected (gs)-COSY, gs-NOESY, gs-HMQC, and gs-HMBC). EI-MS (pos.):
Shimadzu QP-2010 instrument within m/z 50 – 600 using direct inlet probe (DI); analysis of samples in
CH2Cl2 (30 mg/ml), 10 ml of the soln. was evaporated in DI cuvette at 508; ion-source temp., 2008; the
energy of electrons, 70 eV; only signals exceeding rel. abundance of 5% are listed. ESI-MS (pos. as well
as neg.): amaZon X ion-trap mass spectrometer (Bruker Daltonics, D-Bremen) equipped with an ESI
source; individual samples infused into the ion source as MeOH/H2O 1:1 (v/v) solns. via a syringe pump

Helvetica Chimica Acta – Vol. 95 (2012)
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at a constant flow rate of 4 ml/min; other instrumental conditions: m/z range 50 – 1500; electrospray
voltage, ꢁ 4.2 kV; drying gas temp., 220 , drying gas flow, 6.0 dm3/min; nebulizer pressure, 55.16 kPa;
cap. exit ꢁ 140 V; N2 used as nebulizing as well as drying gas. Elemental analysis (C, H, N, S): Flash EA
1112 elemental analyzer (Thermo Fisher Scientific).
2. Starting 3-Thiocyanatoquinoline-2,4-(1H,3H)-diones (¼1,2,3,4-Tetrahydro-2,4-dioxoquinolin-3-yl
Thiocyanates; 2). Compounds 2 were prepared according to the procedure described in [7][16]. Seven
new derivatives, 2a, 2b, 2e, 2f, 2i, 2j, 2l, were prepared. Compound 2l was also prepared by a modification
of this method, using DMF as solvent instead of AcOH.
1,2,3,4-Tetrahydro-3-methyl-2,4-dioxoquinolin-3-yl Thiocyanate (2a). Prepared from 1a in 46%
yield. Yellowish oil. IR 3084, 2989, 1920, 2156, 1709, 1674, 1612, 1597, 1500, 1485, 1441, 1377, 1350, 1321,
1277, 1232, 1159, 1101, 1057, 1009, 964, 908, 872, 760, 665, 579, 525. 1H- and 13C-NMR: see Table 1. EI-MS:
232 (35, Mþ), 204 (20), 176 (7), 175 (64), 174 (11), 147 (11), 146 (65), 128 (22), 120 (58), 119 (100), 118
(11), 117 (16), 93 (12), 92 (44), 91 (20), 90 (16), 77 (22), 76 (12), 65 (24), 64 (20), 63 (18), 59 (28), 55
(21), 51 (12). ESI-MS (pos.): 486.9 (37, [2 M þ Na]þ), 430.0 (25, [2 M þ Na ꢀ SCN þ H]þ), 368.0 (33,
[3 M þ Ca]2þ), 270.9 (44, [M þ K]þ), 255.0 (100, [M þ Na]þ), 250.0 (14, [M þ NH4]þ), 233.0 (5, [M þ
H]þ), 198.0 (5, [M þ Na ꢀ SCN þ H]þ), 176.0 (25, [M þ H ꢀ SCN þ H]þ). ESI-MS (neg.): 230.9 (100,
[M ꢀ H]ꢀ), 173.9 (17, [M ꢀ SCN]ꢀ).
3-Ethyl-1,2,3,4-tetrahydro-2,4-dioxoquinolin-3-yl Thiocyanate (2b). Prepared from 1b in 68% yield.
Yellow crystals. M.p. 103 – 1078 (benzene/hexane). IR: 3217, 3141, 3085, 2987, 2933, 2874, 2738, 2156,
1709, 1659, 1614, 1597, 1506, 1485, 1458, 1434, 1374, 1318, 1299, 1252, 1232, 1156, 1060, 1000, 959, 909, 870,
842, 807, 773, 745, 684, 663, 617, 528, 516. 1H- and 13C-NMR: see Table 1. EI-MS: 246 (4, Mþ), 190 (10),
189 (76), 188 (33), 187 (5), 186 (9), 175 (13), 174 (100), 161 (15), 156 (5), 146 (14), 128 (8), 127 (5), 120
(27), 119 (11), 115 (9), 113 (7), 99 (7), 93 (6), 92 (26), 91 (7), 90 (8), 87 (12), 85 (12), 77 (15), 71 (24), 69
(13), 65 (18), 64 (11), 63 (9), 59 (29), 58 (6), 57 (39), 56 (5), 55 (26), 43 (21), 41 (19). Anal. calc. for
C12H10N2O2S (246.29): C 58.52, H 4.09, N 11.37, S 13.02; found: C 58.34, H 4.11, N 11.27, S 12.92.
1,2,3,4-Tetrahydro-1,3-dimethyl-2,4-dioxoquinolin-3-yl Thiocyanate (2e). Prepared from 1e in 90%
yield. Yellow oil. IR: 3087, 2988, 2944, 2893, 2360, 2342, 2155, 1704, 1667, 1603, 1493, 1473, 1419, 1373,
1357, 1301, 1258, 1177, 1120, 1092, 1046, 969, 903, 761, 664, 613, 584, 530. 1H- and 13C-NMR: see Table 1.
EI-MS: 246 (11, Mþ), 190 (12), 189 (100), 188 (7), 161 (8), 160 (44), 147 (8), 146 (52), 144 (7), 134 (24),
133 (23), 132 (20), 130 (8), 118 (6), 117 (12), 116 (9), 106 (9), 105 (27), 104 (24), 103 (5), 95 (6), 92 (5),
91 (12), 90 (7), 79 (8), 78 (12), 77 (37), 76 (7), 65 (8), 64 (7), 63 (9), 59 (15), 51 (12). ESI-MS (pos.):
515.1 (14, [2 M þ Na]þ), 458.2 (9, [2 M þ Na ꢀ SCN þ H]þ), 389.2 (15, [3 M þ Ca]2þ), 285.1 (20, [M þ
K]þ), 269.2 (100, [M þ Na]þ), 265.2 (17, [M þ NH4]þ), 247.2 (32, [M þ H]þ), 228.2 (13, [M þ K ꢀ
SCN þ H]þ), 212.2 (5, [M þ Na ꢀ SCN þ H]þ), 190.3 (30, [M þ H ꢀ SCN þ H]þ), 188.3 (21, [M ꢀ
SCN]þ). ESI-MS (neg.): 188.1 (100),[M ꢀ SCN]ꢀ).
3-Ethyl-1,2,3,4-tetrahydro-1-methyl-2,4-dioxoquinolin-3-yl Thiocyanate (2f). Prepared from 1f in
67% yield. Yellowish crystals. M.p. 62 – 658 (benzene/cyclohexane). IR: 2992, 2971, 2936, 2155, 1698,
1668, 1603, 1473, 1355, 1242, 1159, 1186, 1031, 818, 778, 755, 660, 462. 1H- and 13C-NMR: see Table 1. EI-
MS: 219 (13), 204 (11), 203 (81), 202 (13), 189 (13), 188 (100), 175 (9), 163 (29), 162 (54), 160 (13), 149
(14), 147 (6), 146 (9), 135 (6), 134 (47), 132 (13), 130 (11), 117 (9), 116 (11), 115 (7), 106 (16), 105 (13),
104 (18), 103 (6), 102 (7), 97 (9), 95 (6), 94 (7), 92 (9), 91 (14), 90 (8), 89 (7), 85 (10), 83 (10), 81 (8), 79
(12), 78 (15), 77 (43), 76 (9), 71 (18), 69 (23), 67 (6), 65 (10), 64 (8), 63 (10), 57 (41). ESI-MS (pos.):
543.1 (14, [2 M þ Na]þ), 486.2 (5, [2 M þ Na ꢀ SCN þ H]þ), 410.2 (10, [3 M þ Ca]2þ), 299.2 (23, [M þ
K]þ), 283.2 (100, [M þ Na]þ), 278.2 (7, [M þ NH4]þ), 261.2 (16, [M þ H]þ), 242.2 (5, [M þ K ꢀ SCN þ
H]þ), 226.2 (5, [M þ Na ꢀ SCN þ H]þ), 204.3 (9, [M þ H ꢀ SCN þ H]þ), 202.3 (8, [M ꢀ SCN]þ). ESI-
MS (neg.): 202.1 (100, [M ꢀ SCN]ꢀ). Anal. calc. for C13H12N2O2S (260.31): C 59.98, H 4.65, N 10.76, S
12.32; found: C 60.25, H 4.72, N 10.60, S 12.12.
1,2,3,4-Tetrahydro-3-methyl-2,4-dioxo-1-phenylquinolin-3-yl Thiocyanate (2i). Prepared from 1i in
71% yield. Yellow crystals. M.p. 132 – 1358 (benzene/hexane). IR: 3065, 3015, 2363, 2154, 1701, 1667,
1601, 1583, 1491, 1464, 1370, 1340, 1304, 1256, 1132, 1166, 1157, 1103, 1071, 1055, 1026, 961, 895, 843, 795,
1
769, 759, 744, 703, 657, 602, 554, 537. H- and 13C-NMR: see Table 1. EI-MS: 308 (9, Mþ), 251 (19), 250
(20), 222 (11), 195 (11), 167 (10), 126 (10), 114 (24), 112 (9), 104 (17), 98 (7), 97 (6), 95 (7), 86 (9), 83
(11), 81 (6), 77 (8), 74 (100), 72 (47), 69 (16), 67 (8), 62 (7), 60 (15), 59 (82), 57 (10), 56 (7), 55 (34), 44

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(15), 43 (24), 41 (17). Anal. calc. for C17H12N2O2S (308.35): C 66.22, H 3.92, N 9.08, S 10.40; found: C
66.19, H 3.88, N 9.08, S 10.28.
3-Ethyl-1,2,3,4-tetrahydro-2,4-dioxo-1-phenylquinolin-3-yl Thiocyanate (2j). Prepared from 1j in
67% yield. Yellowish crystals. M.p. 110 – 1138 (benzene). IR: 3067, 2977, 2934, 2162, 1708, 1673, 1599,
1
1491, 1464, 1346, 1397, 1249, 1100, 1013, 813, 777, 767, 751, 704, 660, 603, 512. H- and 13C-NMR: see
Table 1. EI-MS: 281 (6), 266 (19), 265 (100), 264 (51), 251 (17), 250 (89), 237 (11), 225 (12), 224 (9), 196
(28), 195 (19), 168 (9), 167 (29), 166 (11), 149 (20), 140 (7), 139 (9), 127 (10), 124 (11), 115 (8), 114 (6),
111 (10), 99 (6), 98 (9), 97 (16), 95 (8), 85 (11), 84 (7), 83 (19), 81 (8), 77 (25), 74 (10), 72 (9), 71 (22), 70
(11), 69 (29), 67 (8), 59 (17), 57 (36). ESI-MS (pos.): 667.1 (6, [2 M þ Na]þ), 610.2 (5, [2 M þ Na ꢀ
SCN þ H]þ), 553.3 (5, [2 M þ Na – 2 · SCN þ 2 · H]þ), 503.2 (6, [3 M þ Ca]2þ), 361.2 (26, [M þ K]þ), 345.2
(100, [M þ Na]þ), 340.3 (6, [M þ NH4]þ), 323.2 (19, [M þ H]þ), 304.2 (7, [M þ K ꢀ SCN þ H]þ), 288.3
(18, [M þ Na ꢀ SCN þ H]þ), 266.3 (22, [M þ H ꢀ SCN þ H]þ). ESI-MS (neg.): 264.1 (100, [M ꢀ SCN]ꢀ).
Anal. calc. for C18H14N2O2S (322.38): C 67.06, H 4.38, N 8.69, S 9.95; found: C 66.91, H 4.39, N 8.60, S 9.74.
3-Benzyl-1,2,3,4-tetrahydro-2,4-dioxo-1-phenylquinolin-3-yl Thiocyanate (2l). a) Prepared from 1l in
7% yield according to the procedure described in [7]. Yellowish crystals. M.p. 141 – 1448 (benzene/
hexane). IR: 3080, 3028, 2958, 2924, 2859, 2157, 1708, 1677, 1598, 1492, 1461, 1331, 1298, 1245, 1213, 1183,
1160, 1086, 1071, 1045, 1030, 1002, 957, 944, 923, 806, 765, 750, 703, 661, 611, 581, 502. 1H- and 13C-NMR:
see Table 1. EI-MS: 384 (7, Mþ), 328 (12), 327 (49), 326 (18), 256 (6), 222 (8), 196 (10), 167 (10), 140 (7),
127 (9), 126 (19), 125 (11), 124 (6), 114 (21), 113 (11), 112 (17), 111 (18), 110 (8), 109 (10), 97 (29), 91
(31), 85 (21), 83 (30), 74 (100), 69 (31), 59 (92), 57 (45), 55 (51), 43 (56). Anal. calc. for C23H16N2O2S
(384.45): C 71.85, H 4.19, N 7.29, S 8.34; found: C 71.70, H 4.24, N 7.11, S 8.18.
b) A soln. of 1l (2.45 g, 7.5 mmol) in DMF (37.5 ml) was added in one portion to the stirred soln. of
(SCN)2, prepared by adding Br2 (0.42 ml, 8.25 mmol) to the soln. of KSCN (1.75 g, 18 mmol) in DMF
(38 ml). The stirring was continued for 5 min, and then the mixture was poured into a well-stirred
mixture of H2O (260 ml) and benzene (110 ml). The benzene layer was separated, and the aq. layer was
extracted with benzene (6 ꢂ 50 ml). The collected extracts were washed with H2O (3 ꢂ 40 ml), dried
(anh. Na2SO4), and evaporated to dryness in vacuo. The residue was separated by CC (SiO2; benzene)
and crystallized from benzene/hexane. Yield of 2l: 50%.
3. Modified Riemschneider Reaction of Compounds 2. General Methods. Method A. Compound 2
(2 mmol) was added under vigorous stirring at 08 to a mixture of 96% H2SO4 and AcOH (40 ml, 9 :1 (v/
v)). After dissolution of the starting compounds, P2O5 (4 g, 28 mmol) was added in two portions, and the
mixture was stirred at r.t. The course of the reaction was monitored with TLC. After disappearance of the
spot corresponding to 2 (for reaction time, see Table 2), the mixture was poured onto crushed ice
(400 ml). Deposited precipitate was filtered with suction and washed with H2O. The filtrate was extracted
several times with AcOEt; the soln. was dried (anh. Na2SO4) and evaporated to dryness. The residue was
dissolved in EtOH and filtered. The filtrate was evaporated to dryness, and the residue was crystallized
from the appropriate solvent or separated by CC (SiO2). In some cases, designated with asterisk in
Table 2, the EtOH soln. was alkalized with NH4OH (25%) before filtration.
Method B. The reaction was carried out as in Method A, but 96% H2SO4 (36 ml) was used instead of
its mixture with AcOH.
Method C. The reaction was carried out as in Method B, anh. AlCl3 (3.7 g, 14 mmol) was added
instead of P2O5.
S-(1,2,3,4-Tetrahydro-3-methyl-2,4-dioxoquinolin-3-yl) Carbamothioate (3a). Prepared from 2a in
35% yield (Method B). Colorless crystals. M.p. 172 – 1748 and then 266 – 2728 (AcOEt). IR: 3400, 3227,
3174, 3067, 2927, 2867, 1698, 1662, 1610, 1597, 1486, 1446, 1380, 1354, 1324, 1230, 1103, 969, 806, 786, 751,
676, 623, 529. 1H- and 13C-NMR: see Table 3. EI-MS: 176 (11), 175 (100, [M ꢀ SCONH]þ), 174 (11), 147
(9), 146 (32), 129 (5), 128 (5), 120 (70), 119 (38), 118 (8), 117 (6), 104 (9), 93 (17), 92 (34), 91 (10), 90
(6), 88 (6), 77 (15), 76 (6), 74 (14), 65 (24), 64 (5), 63 (10), 59 (7), 55 (14), 51 (10). ESI-MS (pos.): 373.2
(100, [2 M þ Na – 2 · SCONH]þ), 198.2 (46, [M þ Na ꢀ SCONH]þ), 176.2 (46, [M þ H ꢀ SCONH]þ).
ESI-MS (neg.): 174.1 (100, [M ꢀ H ꢀ SCONH]ꢀ). Anal. calc. for C11H10N2O3S (250.27): C 52.79, H 4.03,
N 11.19, S 12.81; found: C 52.88, H 4.03, N 11.17, S 12.65.
S-(3-Ethyl-1,2,3,4-tetrahydro-2,4-dioxoquinolin-3-yl) Carbamothioate (3b). Prepared from 2b in
42% yield (Method B). Colorless crystals. M.p. 173 – 1798 (AcOEt). IR: 3407, 3382, 3302, 3254, 3184,

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2974, 1678, 1667, 1653, 1612, 1598, 1488, 1362, 1296, 1160, 848, 776, 753, 678, 667, 622, 594, 528. 1H- and
13C-NMR: see Table 3. EI-MS: 221 (30, [M ꢀ CONH]þ), 206 (15), 193 (24), 190 (9), 189 (76, [M ꢀ
SCONH]þ), 188 (38), 175 (11), 174 (100), 170 (6), 161 (15), 149 (6), 148 (10), 146 (19), 132 (6), 130
(10), 128 (9), 120 (47), 119 (17), 117 (7), 116 (5), 115 (11), 93 (6), 92 (34), 91 (9), 90 (13), 89 (6), 87 (12),
77 (18), 76 (7), 74 (15), 73 (20), 69 (14), 66 (7), 65 (21), 64 (42), 63 (12), 59 (6), 55 (18), 50 (5). ESI-MS
(pos.): 551.1 (5, [2 M þ Na]þ), 476.2 (25, [2 M þ Na ꢀ SCONH]þ), 401.2 (91, [2 M þ Na – 2 · SCONH]þ),
303.2 (20, [M þ K]þ), 287.2 (100, [M þ Na]þ), 212.2 (56, [M þ Na ꢀ SCONH]þ), 190.2 (56, [M þ H ꢀ
SCONH]þ). ESI-MS (neg.): 188.1 (100, [M ꢀ H ꢀ SCONH]ꢀ). Anal. calc. for C12H12N2O3S (264.30):
C 54.53, H 4.58, N 10.60, S 12.13; found: C 54.48, H 4.56, N 10.53, S 11.86.
S-(3-Butyl-1,2,3,4-tetrahydro-2,4-dioxoquinolin-3-yl) Carbamothioate (3c). Prepared from 2c by
Method A in 52% yield. Colorless crystals. M.p. 163 – 1658 (AcOEt/benzene). Identical in all respects to
1
an authentic sample [16]. H- and 13C-NMR: see Table 3.
S-(3-Butyl-1,2,3,4-tetrahydro-2,4-dioxo-1-phenylquinolin-3-yl) Carbamothioate (3k). Prepared from
2k in 40 (Method B) and 23% yield (Method C), resp. Yellowish crystals. M.p. 177 – 1828 (benzene/
hexane). IR: 3395, 3202, 2955, 2872, 1684, 1667, 1655, 1601, 1491, 1464, 1346, 1303, 761, 749, 701, 687, 662.
1H- and 13C-NMR: see Table 3. EI-MS: 368 (1, Mþ), 293 (18, [M ꢀ SCONH]þ), 264 (33), 252 (18), 251
(100), 250 (53), 237 (9), 196 (16), 195 (11), 168 (8), 167 (12), 166 (5), 77 (14), 51 (7). Anal. calc. for
C20H20N2O3S (368.45): C 65.20, H 5.47, N 7.60, S 8.70; found: C 65.38, H 5.48, N 7.51, S 8.57.
3a-Methyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4a). Prepared from 2a in 7% yield
(Method B). Yellow crystals. M.p. 187 – 1898 and then 274 – 2808 (benzene/hexane). IR: 3215, 3164, 3111,
3060, 2993, 2921, 2856, 1724, 1700, 1610, 1589, 1574, 1503, 1475, 1379, 1344, 1275, 1239, 1155, 1132, 1106,
1077, 1028, 972, 960, 780, 755, 674, 643, 288, 526. 1H- and 13C-NMR: see Table 4. EI-MS: 234 (6), 233 (13),
232 (100, Mþ), 204 (7), 203 (31), 175 (30), 174 (7), 171 (11), 160 (6), 146 (15), 145 (23), 144 (7), 120 (25),
119 (13), 118 (15), 117 (14), 116 (8), 102 (15), 93 (6), 92 (12), 91 (7), 90 (13), 89 (7), 77 (7), 76 (7), 75
(7), 65 (9), 64 (9), 63 (10), 60 (13), 59 (52), 58 (6), 51 (9). Anal. calc. for C11H8N2O2S (232.26): C 56.88,
H 3.47, N 12.06, S 13.81; found: C 56.81, H 3.31, N 12.03, S 13.65.
3a-Ethyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4b). Prepared from 2b in 7 (Method A),
18 (Method B), and 18% yield (Method C), resp. Yellow crystals. M.p. 186 – 1988 (AcOEt). IR: 3209,
3152, 3056, 2978, 2965, 2927, 2857, 1721, 1698, 1609, 1567, 1505, 1476, 1435, 1360, 1336, 1266, 1242, 1155,
1
1137, 1081, 1035, 1011, 978, 960, 926, 873, 804, 772, 745, 694, 674, 642, 590, 526. H- and 13C-NMR: see
Table 4. EI-MS: 247 (14), 246 (100, Mþ), 232 (7), 231 (44), 217 (8), 204 (5), 203 (47), 185 (12), 184 (6),
175 (9), 171 (11), 145 (8), 129 (8), 128 (6), 127 (7), 126 (6), 125 (7), 123 (7), 118 (6), 117 (11), 116 (10),
115 (6), 114 (5), 113 (6), 112 (5), 111 (10), 110 (6), 109 (8), 102 (12), 101 (7), 100 (24), 99 (7), 98 (8), 97
(14), 96 (7), 95 (11), 87 (7), 86 (7), 85 (14), 84 (10), 83 (20), 82 (8), 81 (12), 79 (9), 74 (21), 73 (24), 72
(20), 71 (29), 70 (12), 69 (26), 67 (9), 60 (6), 59 (23), 58 (16), 57 (34), 56 (9), 55 (28). Anal. calc. for
C12H10N2O2S (246.29): C 58.52, H 4.09, N 11.37, S 13.02; found: C 58.20, H 4.12, N 11.21, S 12.86.
3a-Butyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4c). Prepared from 2c in 10 and 14%
yield (Method A), resp. Yellow crystals. M.p. 180 – 1858 (AcOEt/benzene). Identical in all respects to the
authentic sample [16].
3a,5-Dimethyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4e). Prepared from 2e in 18
(Method A), 8 (Method B*), and 4% yield (Method C*), resp. Yellow crystals. M.p. 147 – 1498
(benzene/hexane). IR: 3083, 2985, 2929, 1724, 1685, 1592, 1571, 1470, 1420, 1382, 1351, 1292, 1176, 1133,
1095, 1061, 1042, 970, 933, 867, 774, 755, 690, 663, 643, 601, 549, 525. 1H- and 13C-NMR: see Table 4. EI-
MS: 247 (15), 246 (100, Mþ), 214 (15), 189 (8), 188 (24), 187 (6), 186 (6), 185 (10), 160 (14), 143 (7), 132
(9), 131 (6), 116 (7), 109 (6), 102 (11), 89 (5), 77 (10), 76 (6), 75 (6), 63 (5), 59 (53), 51 (6). Anal. calc.
for C12H10N2O2S (246.29): C 58.52, H 4.09, N 11.37, S 13.02; found: C 58.37, H 4.06, N 11.29, S 12.82.
3a-Ethyl-5-methyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4f). Prepared from 2f in 41
(Method A), 53 (Method B*), and 42% yield (Method C), resp. Yellow crystals. M.p. 111 – 1138
(benzene/hexane). IR: 2973, 1717, 1679, 1601, 1583, 1472, 1356, 1291, 1128, 1094, 1068, 1038, 1009, 953,
784, 768,748, 694, 683. 1H and 13C-NMR: see Table 4. EI-MS: 261 (12), 260 (70, Mþ), 245 (16), 232 (42),
231 (9), 228 (24), 227 (19), 217 (12), 213 (17), 200 (20), 199 (20), 189 (6), 188 (27), 187 (26), 185 (12),
173 (7), 167 (33), 163 (8), 162 (6), 160 (10), 159 (7), 155 (6), 150 (12), 149 (100), 145 (6), 142 (8), 141
(9), 131 (6), 127 (12), 125 (11), 116 (11), 113 (18), 111 (16), 109 (10), 105 (13), 104 (11), 102 (12), 100

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(80), 97 (19), 95 (11), 85 (16), 83 (29), 81 (18), 77 (16), 76 (12), 73 (12), 72 (33), 71 (66), 70 (26), 69 (38),
59 (37), 57 (70). Anal. calc. for C13H12N2O2S (260.31): C 59.98, H 4.65, N 10.76, S 12.32; found: C 60.18, H
4.64, N 10.75, S 12.04.
3a-Butyl-5-methyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4g). Prepared from 2g in 21
(Method B), 18 (Method B*), and 4% yield (Method C*), resp. Yellow crystals. M.p. 109 – 1108 (benzene/
1
hexane). H- and 13C-NMR: see Table 4. Identical in all respects to an authentic sample [16].
3a-Methyl-5-phenyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4i). Prepared from 2i in 69
(Method A), 4 (Method B), and 2% yield (Method C*), resp. Yellow crystals. M.p. 206 – 2098 (benzene/
hexane). IR: 3383, 3088, 3049, 3036, 2998, 2938, 1712, 1698, 1603, 1587, 1491, 1465, 1381, 1340, 1296, 1273,
1
1252, 1161, 1122, 1079, 1041, 1009, 966, 931, 868, 852, 768, 755, 745,723, 703, 691, 644, 616, 512. H- and
13C-NMR: see Table 4. EI-MS: 309 (19), 308 (92, Mþ), 307 (14), 278 (6), 277 (35), 276 (86), 275 (100),
251 (7), 250 (31), 249 (23), 248 (8), 247 (12), 221 (6), 219 (11), 205 (11), 204 (12), 194 (10), 193 (5), 192
(6), 167 (10), 151 (5), 150 (6), 149 (49), 140 (10), 139 (6), 138 (5), 128 (11), 127 (5), 125 (8), 111 (12),
109 (11), 103 (11), 102 (19), 97 (17), 95 (11), 85 (15), 83 (22), 81 (11), 77 (42), 71 (35), 70 (14), 69 (26),
60 (15), 59 (42), 57 (46), 56 (13), 55 (22), 51 (20), 45 (29), 43 (61), 41 (32). Anal. calc. for C17H12N2O2S
(308.35): C 66.22, H 3.92, N 9.08, S 10.40; found: C 65.97, H 3.86, N 8.99, S 10.23.
3a-Ethyl-5-phenyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4j). Prepared from 2j in 61
(Method A), 12 (Method B*), and 35% yield (Method C*), resp. Yellow crystals. M.p. 191 – 1938
(benzene/AcOEt). IR: 3079, 3051, 2979, 2966, 2932, 2874, 1719, 1688, 1603, 1584, 1491, 1462, 1380, 1349,
1328, 1299, 1283, 1266, 1246, 1162, 1153, 1098, 1076, 1038, 1027, 993, 955, 919, 805, 782, 764, 754, 732, 704,
682, 644, 619, 534, 516. 1H- and 13C-NMR: see Table 4. EI-MS: 324 (7), 323 (22), 322 (100, Mþ), 307 (22),
294 (21), 293 (10), 289 (11), 279 (11), 262 (8), 261 (8), 250 (25), 249 (10), 203 (6), 194 (8), 188 (9), 109
(5), 102 (6), 77 (35), 73 (39), 71 (7), 57 (8), 51 (17). Anal. calc. for C18H14N2O2S (322.38): C 67.06, H
4.38, N 8.69, S 9.95; found: C 67.11, H 4.34, N 8.63, S 9.75.
3a-Butyl-5-phenyl[1,3]thiazolo[5,4-c]quinoline-2,4(3aH,5H)-dione (4k). Prepared from 2k in 15 and
54 (Method A), 23 (Method A*), 23 (Method B), and 51% yield (Method C), resp. Yellow crystals. M.p.
1
158 – 1608 (benzene/hexane). H- and 13C-NMR: see Table 4. Identical in all respects to an authentic
sample [16].
[1,3]Thiazolo[5,4-c]quinoline-2,4(1H,5H)-dione (5c). Prepared from 2c in 43 (Method A) and 34%
yield (Method C), resp., using prolonged reaction times. Beige crystals. M.p. > 3208 (DMF). IR: 3150,
3111, 3000, 2970, 2883, 2850, 2693, 1665, 1646, 1600, 1543, 1424, 1387, 1277, 1175, 1138, 917, 859, 755, 727,
680, 622, 506. 1H- and 13C-NMR: see Table 7. EI-MS: 219 (13), 218 (100, Mþ), 162 (23), 157 (14), 146 (6),
145 (6), 129 (20), 118 (11), 109 (9), 103 (7), 102 (9), 91 (7), 81 (8), 76 (9). Anal. calc. for C10H6N2O2S
(218.23): C 55.04, H 2.77, N 12.84, S 14.69; found: C 55.07, H 2.75, N 12.69, S 14.51.
5-Methyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,5H)-dione (5g). Prepared from 2g in 63 (Method A),
1 (Method B), and 3% yield (Method B*), resp. Colorless crystals. M.p. > 3308 (DMF). IR: 3113, 3050,
2986, 2893, 2819, 1712, 1627, 1617, 1585, 1564, 1528, 1464, 1451, 1429, 1374, 1347, 1216, 1187, 1156, 1118,
1079, 1047, 978, 946, 846, 751, 726, 691, 664, 653, 622, 556, 542. 1H- and 13C-NMR: see Table 7. EI-MS: 233
(14), 232 (100, Mþ), 189 (6), 176 (12), 175 (6), 171 (8), 161 (7), 132 (9), 131 (9), 117 (6), 115 (11), 104
(6), 102 (12), 77 (7), 76 (7). Anal. calc. for C11H8N2O2S (232.26): C 56.88, H 3.47, N 12.06, S 13.81; found:
C 56.86, H 3.57, N 11.87, S 13.57.
5-Phenyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,5H)-dione (5k). Prepared from 2k in 34% yield
1
(Method A; prolonged reaction time). Colorless crystals. M.p. 329 – 3318 (AcOEt). H- and 13C-NMR:
see Table 7. Identical in all respects to an authentic sample [16].
5,9b-Dihydro-9b-hydroxy-3a-methyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,3aH)-dione (6a). Pre-
pared from 2a in 46 (Method A) and 8% yield (Method C*), resp. Colorless crystals. M.p. 179 – 1838
and then 227 – 2368 (THF/hexane). IR: 3297, 3238, 3064, 2984, 2929, 1677, 1667, 1600, 1497, 1439, 1393,
1378, 1352, 1258, 1197, 1161, 1140, 1122, 1098, 1072, 1053, 1039, 951, 926, 828, 776, 757, 717, 704, 680, 643,
608, 567, 535, 501. 1H- and 13C-NMR: see Table 5. EI-MS: 250 (5, Mþ), 207 (21), 176 (10), 175 (92), 174
(13), 159 (19), 157 (9), 149 (11), 148 (9), 147 (9), 146 (33), 142 (11), 141 (100), 140 (11), 139 (7), 130 (6),
129 (7), 128 (11), 123 (7), 121 (6), 120 (71), 119 (42), 118 (8), 104 (6), 98 (8), 97 (95), 95 (6), 93 (18), 92
(35), 91 (10), 90 (7), 85 (7), 84 (6), 81 (7), 77 (14), 76 (5), 70 (12), 69 (10), 66 (6), 65 (20), 64 (36), 63

Helvetica Chimica Acta – Vol. 95 (2012)
1367
Table 7. 1H- and 13C-NMR Data ((D6)DMSO) of Compounds 5 and 12 (d in ppm)
Position
5c
5g
5k
12d
12l
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
1
2
3a
4
5a
6
7
8
9
9a
9b
13.0
–
–
–
–
7.45
7.60
7.32
8.03
–
–
13.01
–
–
–
–
7.72
7.72
7.45
8.11
–
–
13.12
–
–
–
–
6.66
7.52
7.37
8.14
–
–
–
–
–
–
–
–
–
–
–
–
156.3
108.7
171.8
137.8
116.4
130.5
122.3
122.7
110.2
140.3
155.7
108.6
171.1
138.6
116.1
131.0
122.6
123.3
111.1
139.3
155.7
108.6
171.7
139.8
116.7
130.7
122.8
123.2
110.9
140.0
156.1
110.4
168.5
137.7
116.4
131.6
123.1
121.8
109.2
150.6
155.6
110.4
168.4
139.8
116.7
131.4
123.6
122.5
110.1
150.4
–
–
7.51
7.69
7.38
7.80
–
6.73
7.62
7.46
7.96
–
–
–
–
–
–
Substituent at N(1)
1
2
3
4
12.05
–
–
–
–
3.73
29.5
–
137.2
129.4
130.2
129.1
12.46
–
–
–
–
–
136.7
129.2
130.4
129.5
–
–
–
–
–
–
–
–
–
7.41
7.68
7.63
–
–
–
7.44
7.71
7.66
(8), 59 (10), 55 (12), 51 (9), 44 (8), 43 (43), 42 (22), 41 (11). Anal. calc. for C11H10N2O3S (250.27): C
52.79, H 4.03, N 11.19, S 12.81; found: C 52.81, H 4.21, N 11.03, S 12.65.
3a-Ethyl-5,9b-dihydro-9b-hydroxy[1,3]thiazolo[5,4-c]quinoline-2,4(1H,3aH)-dione (6b). Prepared
from 1b in 40% yield (Method A). Colorless crystals. M.p. 175 – 1798 (AcOEt). IR: 3481, 3193, 3075,
2981, 2933, 1689, 1667, 1599, 1497, 1440, 1376, 1315, 1291, 1251, 1212, 1132, 1108, 1076, 1046, 998, 947, 893,
1
849, 755, 680, 655, 630, 609, 567, 542. H- and 13C-NMR: see Table 5. EI-MS: 264 (1, Mþ), 246 (1), 221
(17), 206 (10), 193 (15), 189 (76), 188 (36), 175 (12), 174 (100), 170 (6), 161 (15), 149 (11), 148 (6), 146
(17), 132 (5), 130 (9), 128 (8), 120 (39), 119 (14), 117 (6), 115 (10), 100 (7), 93 (6), 92 (29), 91 (8), 90
(10), 89 (6), 87 (7), 86 (6), 77 (18), 76 (7), 73 (7), 71 (6), 69 (14), 65 (19), 64 (37), 63 (10), 55 (21), 51
(8). Anal. calc. for C12H12N2O3S (264.30): C 54.53, H 4.58, N 10.60, S 12.13; found: C 54.67, H 4.61, N
10.55, S 12.05.
5,9b-Dihydro-9b-hydroxy-3a,5-dimethyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,3aH)-dione (6e). Pre-
pared from 2e in 63 (Method A) and 3% yield (Method C*), resp. Colorless crystals. M.p. 172 – 1768
(AcOEt). IR: 3318, 3216, 3079, 2996, 2924, 2830, 1680, 1640, 1605, 1597, 1504, 1471, 1445, 1414, 1382,
1367, 1298, 1258, 1206, 1185, 1135, 1103, 1090, 1070, 1054, 948, 919, 870, 841, 770, 759, 727, 690, 650, 589,
553, 511. 1H- and 13C-NMR: see Table 5. EI-MS: 264 (18, Mþ), 246 (5), 222 (6), 221 (46), 190 (12), 189
(89), 188 (10), 177 (6), 165 (6), 164 (27), 163 (53), 162 (58), 161 (21), 160 (50), 147 (10), 146 (45), 145
(6), 144 (8), 134 (37), 133 (28), 132 (27), 131 (8), 130 (12), 127 (5), 125 (5), 123 (7), 117 (19), 105 (35),
104 (34), 97 (15), 91 (17), 85 (20), 83 (18), 78 (19), 77 (56), 71 (33), 64 (22), 57 (38), 55 (28), 43 (100).
Anal. calc. for C12H12N2O3S (264.30): C 54.53, H 4.58, N 10.60, S 12.13; found: C 54.35, H 4.61, N 10.49, S
11.93.
3a-Ethyl-5,9b-dihydro-9b-hydroxy-5-methyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,3aH)-dione (6f).
Prepared from 2f in 16% yield (Method A). Colorless crystals. M.p. 104 – 1068 and then 118 – 1238
(CHCl3). IR: 3293, 3179, 1680, 1647, 1604, 1478, 1372, 1251, 1209, 1181, 1164, 1116, 1078, 1056, 977, 861,
817, 766, 687, 622, 471, 459. 1H- and 13C-NMR: see Table 5. EI-MS: 279 (5), 278 (33, Mþ), 235 (17), 208
(8), 207 (61), 204 (11), 203 (80), 202 (44), 189 (13), 188 (100), 178 (15), 175 (11), 174 (6), 163 (32), 162
(30), 161 (8), 160 (16), 147 (7), 146 (16), 135 (7), 134 (64), 133 (10), 132 (17), 131 (7), 130 (14), 117 (11),
116 (13), 115 (8), 106 (14), 105 (18), 104 (25), 103 (7), 102 (9), 94 (8), 92 (8), 91 (13), 90 (9), 89 (7), 79
(12), 78 (18), 77 (49), 76 (10), 75 (6), 73 (19), 69 (20), 66 (5), 65 (9), 64 (17), 55 (7), 51 (15). Anal. calc.
for C13H14N2O3S (278.33): C 56.10, H 5.07, N 10.06, S 11.52; found: C 55.81, H 5.07, N 9.82, S 11.29.

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Helvetica Chimica Acta – Vol. 95 (2012)
3a-Ethyl-5,9b-dihydro-9b-hydroxy-5-phenyl[1,3]thiazolo[5,4-c]quinoline-2,4(1H,3aH)-dione (6j).
Prepared from 2j in 8% yield by Method A. Colorless crystals. M.p. 250 – 2568 (AcOEt). IR: 3369,
3187, 3073, 2976, 2876, 1682, 1657, 1602, 1497, 1466, 1456, 1354, 1328, 1305, 1262, 1206, 1131, 1073, 1049,
1004, 978, 927, 852, 805, 767, 753, 724, 701, 636, 621, 574, 516. 1H- and 13C-NMR: see Table 5. EI-MS: 340
(1, Mþ), 322 (5), 269 (10), 266 (18), 265 (100), 264 (50), 251 (16), 250 (88), 237 (11), 196 (25), 195 (22),
167 (27), 166 (12), 92 (8), 77 (31), 69 (12), 64 (20), 51 (16). Anal. calc. for C18H16N2O3S (340.40): C 63.51,
H 4.74, N 8.23, S 9.42; found: C 63.42, H 4.74, N 8.19, S 9.21.
3-Ethyl-3-hydroxy-1-methylquinoline-2,4(1H,3H)-dione (7f). Prepared from 2f in 4% yield (Method
A). M.p. 145 – 1468 (AcOEt/benzene). Identical in all respects to the authentic sample, prepared
according to [22].
3-Butyl-3-hydroxy-1-methylquinoline-2,4(1H,3H)-dione (7g). Prepared from 2g in 4% yield
(Method B*). Colorless crystals. M.p. 123 – 1258 (hexane). Identical in all respects to an authentic
sample [23].
3-Ethyl-3-hydroxy-1-phenylquinoline-2,4(1H,3H)-dione (7j). Prepared from 2j in 7% yield (Method
B*). Colorless crystals. M.p. 196 – 2018 (EtOH/AcOEt). Identical in all respects to an authentic sample
[23].
1-(1,2-Dihydro-1,3-dimethyl-2-oxoquinolin-4-yl)urea (8e). Prepared from 2e in 29% yield (Method
B*) and 23% yield (Method C*), resp., from 4e in 20% yield (Method D), and from 6e (Method D) in
79% yield (Method D), resp. Colorless crystals. M.p. 197 – 2008 (AcOEt). IR: 3398, 3190, 2943, 1673,
1642, 1607, 1577, 1506, 1462, 1420, 1401, 1372, 1343, 1290, 1216, 1183, 1165, 1120, 1096, 1045, 982, 945, 902,
832, 817, 753, 678, 655, 621, 605, 562, 460. 1H- and 13C-NMR: see Table 6. EI-MS: 232 (10), 231 (73, Mþ),
230 (9), 216 (32), 215 (29), 214 (100), 189 (7), 188 (43), 187 (23), 186 (12), 185 (33), 173 (16), 172 (8),
161 (9), 160 (20), 159 (48), 158 (12), 156 (10), 145 (20), 144 (16), 143 (20), 132 (10), 131 (13), 130 (17),
129 (12), 128 (12), 117 (17), 116 (13), 115 (14), 103 (14), 102 (17), 89 (12), 77 (27), 76 (11), 63 (10), 51
(14), 44 (14), 43 (12). ESI-MS (pos.): 463.2 (13, [2 M þ H]þ), 401.2 (100, [2 M þ Na – 2 · NCO]þ), 212.2
(41, [M þ Na ꢀ NCO]þ), 190.2 (41, [M þ H ꢀ NCO]þ). ESI-MS (neg.): 188.1 (100, [M ꢀ H ꢀ NCO]ꢀ).
Anal. calc. for C12H13N3O2 (231.25): C 62.33, H 5.67, N 18.17; found: C 62.39, H 5.81, N 18.19.
1-(3-Butyl-1,2-dihydro-1-methyl-2-oxoquinolin-4-yl)urea (8g). Prepared from 2g in 18 (Method B*)
and 10% yield (Method C*), resp., and from 4g in 50% yield (Method D). Colorless crystals. M.p. 250 –
2588 (EtOH). IR: 3418s, 3293, 3246, 2956, 2934, 2869, 1665, 1633, 1593, 1573, 1528, 1499, 1463, 1413, 1386,
1354, 1295, 1227, 1164, 1123, 1098, 753, 672, 634, 597, 572, 541. 1H- and 13C-NMR: see Table 6. EI-MS: 273
(24, Mþ), 256 (18), 244 (19), 241 (8), 232 (10), 231 (71), 230 (28), 227 (27), 216 (31), 215 (29), 214 (100),
213 (53), 201 (52), 199 (16), 188 (71), 187 (79), 185 (16), 184 (11), 159 (20), 144 (12), 143 (10), 132 (9),
131(11), 130 (15), 117 (14), 116 (11), 115 (14), 103 (10), 77 (20), 44 (14), 43 (14). ESI-MS (pos.): 569.3
(37, [2 M þ Na]þ), 429.8 (10, [3 M þ Ca]2þ), 312.2 (29, [M þ K]þ), 296.3 (100, [M þ Na]þ), 293.3 (12,
[2 M þ Ca]2þ), 274.3 (53, [M þ H]þ). ESI-MS (neg.): 581.0 (5, [2 M þ Cl]ꢀ), 545.2 (21, [2 M ꢀ H]ꢀ), 308.2
(26, [M þ Cl]ꢀ), 272.2 (100, [M ꢀ H]ꢀ), 229.2 (35, [M ꢀ NH2CO]ꢀ). Anal. calc. for C15H19N3O2 (273.33):
C 65.91, H 7.01, N 15.37; found: C 65.80, H 7.06, N 15.52.
1-(1,2-Dihydro-3-methyl-2-oxo-1-phenylquinolin-4-yl)urea (8i). Prepared from 2i in 25 (Method B*)
and 22% yield (Method C*), resp. Colorless crystals. M.p. 275 – 2788 (AcOEt). IR: 3489, 3454, 3325, 3199,
3055, 1678, 1628, 1601, 1587, 1562, 1496, 1452, 1377, 1356, 1334, 1304, 1288, 1228, 1182, 1135, 1113, 1043,
1003, 964, 901, 754, 696, 661, 651, 617, 546, 515. 1H- and 13C-NMR: see Table 6. EI-MS: 252 (17), 251 (100,
[M ꢀ NCO]þ), 250 (90), 222 (8), 196 (9), 195 (31), 194 (8), 167 (23), 166 (9), 146 (9), 126 (8), 92 (6), 84
(11), 77 (20), 51 (11). ESI-MS (pos.): 525.2 (56, [2 M þ Na – 2 · NCO]þ), 396.7 (18, [3 M þ Ca – 3 ·
NCO]2þ), 290.2 (10, [M þ K ꢀ NCO]þ), 274.2 (65, [M þ Na ꢀ NCO]þ), 252.3 (100, [M þ H ꢀ NCO]þ).
ESI-MS (neg.): 250.1 (100, [M ꢀ H ꢀ NCO]ꢀ). Anal. calc. for C17H15N3O2 (293.32): C 69.61, H 5.15, N
14.33; found: C 69.55, H 4.86, N 14.12.
1-(3-Butyl-1,2-dihydro-2-oxo-1-phenylquinolin-4-yl)urea (8k). Prepared from 2k in 26% yield
(Method A*). Colorless needles. M.p. 228 – 2308 (EtOH). IR: 3436, 3214, 2954, 2924, 2857, 1670, 1630,
1601, 1570, 1521, 1492, 1454, 1359, 1228, 1174, 1115, 748, 698, 648, 592, 526. 1H- and 13C-NMR: see
Table 6. EI-MS: 335 (1, Mþ), 318 (8), 303 (6), 290 (10), 289 (21), 277 (21), 276 (100), 275 (51), 263 (6),
262 (5), 261 (23), 204 (9), 77 (15), 51 (7). Anal. calc. for C20H21N3O2 (335.40): C 71.62, H 6.31, N 12.53;
found: C 71.37, H 6.34, N 12.49.

Helvetica Chimica Acta – Vol. 95 (2012)
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4-Amino-3-butyl-1-phenylquinolin-2(1H)-one (9k). Prepared from 2k in 4% yield (Method A*).
Colorless crystals. M.p. 263 – 2708 (AcOEt). Identical in all respects to an authentic compound [24].
Butyl (3-Butyl-1,2-dihydro-1-methyl-2-oxoquinolin-4-yl)carbamate (10g). Prepared in 75% yield by
boiling a soln. of 8g in BuOH for 2 h. Colorless crystals. M.p. 108 – 1128 (cyclohexane). IR: 3265, 2958,
2931, 2871, 1716, 1695, 1637, 1591, 1572, 1508, 1498, 1460, 1414, 1381, 1315, 1277, 1244, 1167, 1101, 1086,
1063, 1037, 1007, 943, 906, 874, 775, 754, 746, 683, 658, 638, 567, 544. 1H- and 13C-NMR: see Table 6. EI-
MS: 331 (7), 330 (32, Mþ), 313 (14), 301 (10), 289 (19), 288 (100), 259 (6), 257 (7), 246 (19), 245 (35),
232 (13), 231 (20), 229 (8), 227 (7), 215 (17), 214 (49), 213 (58), 201 (20), 199 (11), 189 (9), 188 (61), 187
(28), 185 (8), 130 (7), 159 (11), 149 (18), 145 (6), 144 (7), 131 (7), 130 (8), 77 (9), 57 (24), 55 (12). Anal.
calc. for C19H26N2O3 (330.42): C 69.06, H 7.93, N 8.48; found: C 68.83, H 7.83, N 8.45.
4-Hydroxyquinolin-2(1H)-one (11d). Prepared from 2d (Method B) in 6 and from 12d (Method D)
in 50% yield. Colorless crystals. M.p. > 3508. Identical in all respects to an authentic compound (Aldrich
86-59-9).
4-Hydroxy-1-phenylquinolin-2(1H)-one (11l). Prepared from 2l in 9 (Method A), 4 (Method B), 3
(Method B*), and 5% yield (Method C*), and from 12l in 61% yield (Method D), resp. Colorless crystals.
M.p. > 3508. Identical in all respects to an authentic compound prepared in 51% yield from Ph2NH and
malonic acid according to [25].
[1,3]Oxathiolo[4,5-c]quinoline-2,4(5H)-dione (12d). Prepared from 2d in 48 (Method A) and 5%
yield (Method B), resp. Beige crystals. M.p. 344 – 3488 (AcOH). IR: 3001, 2956, 2925, 2843, 1762, 1735,
1650, 1622, 1602, 1567, 1501, 1477, 1442, 1386, 1332, 1271, 1165, 1149, 1128, 1095, 992, 912, 896, 869, 757,
729, 676, 657, 635, 603, 536. 1H- and 13C-NMR: see Table 7. EI-MS: 220 (12), 219 (100, Mþ), 192 (5), 191
(47), 163 (22), 146 (33), 141 (8), 136 (6), 135 (60), 130 (6), 120 (7), 119 (18), 109 (9), 108 (15), 104 (9),
97 (15), 92 (21), 91 (8), 90 (12), 85 (9), 83 (7), 76 (17), 75 (5), 74 (10), 71 (31), 70 (11), 69 (15), 64 (20),
63 (16), 57 (17), 55 (9), 50 (10), 43 (18). Anal. calc. for C10H5NO3S (219.22): C 54.79, H 2.30, N 6.39, S
14.63; found: C 54.75, H 2.38, N 6.22, S 14.52.
5-Phenyl[1,3]oxathiolo[4,5-c]quinoline-2,4(5H)-dione (12l). Prepared from 2l in 7 (Method A) and
26% yield (Method B), resp. Colorless needles. M.p. 243 – 2478 (benzene). IR: 3058, 1780, 1757, 1662,
1595, 1558, 1496, 1489, 1446, 1388, 1329, 1296, 1259, 1219, 1153, 1105, 1088, 1036, 997, 949, 883, 810, 769,
754, 744, 731, 702, 656, 627, 611, 548, 511. 1H- and 13C-NMR: see Table 7. EI-MS: 297 (7), 296 (19), 295
(100, Mþ), 267 (12), 240 (11), 239 (64), 238 (25), 211 (12), 210 (14), 195 (10), 167 (21), 166 (12), 146 (17),
140 (8), 139 (9), 121 (17), 92 (9), 84 (27), 77 (32), 76 (16), 75 (5), 71 (6), 63 (8), 51 (25), 50 (10). Anal.
calc. for C16H9NO3S (295.31): C 65.07, H 3.07, N 4.74, S 10.86; found: C 64.88, H 2.95, N 4.75, S 10.65.
4. Purification of the Crude Mixtures Md, Mh, and Ml. Mixtures of compounds 13, 14, and 15 were
obtained from compounds 2d, 2h, and 2l in yields given in Table 2. After separation by fractional
crystallization, the following pure compounds were isolated.
3,3’-Sulfanediylbis(4-hydroxyquinolin-2(1H)-one) (13d). Isolated from Md. Yellowish crystals. M.p.
> 3208 (DMF). For 13d, a m.p. of 3708 (dec.) was reported in [26]. IR: 3138, 3072, 2949, 2860, 2742, 1649,
1604, 1541, 1494, 1477, 1421, 1367, 1350, 1313, 1263, 1163, 1147, 1109, 1080, 1028, 947, 870, 785, 750, 717,
671, 644, 542, 468. 1H- and 13C-NMR: see Table 8. EI-MS: 353 (11), 352 (51, Mþ), 335 (6), 334 (28, [M ꢀ
H2O]þ), 319 (11), 162 (34), 161 (100), 146 (10), 133 (16), 120 (52), 119 (49), 105 (11), 104 (12), 92 (45),
77 (19), 76 (9), 65 (22), 64 (19), 63 (12), 51 (11). ESI-MS (pos.): 391.0 (27, [M þ K]þ), 375.0 (100, [M þ
Na]þ), 353.1 (40, [M þ H]þ). ESI-MS (neg.): 351.0 (100, [M ꢀ H]ꢀ). Anal. calc. for C18H12N2O4S
(352.36): C 61.35, H 3.43, N 7.95, S 9.10; found: C 61.12, H 3.23, N 8.15, S 8.84.
3,3’-Sulfanediylbis(4-hydroxy-1-phenylquinolin-2(1H)-one) (13l). Isolated from Ml. Beige crystals.
M.p. 325 – 3268 (benzene/hexane). IR: 3034, 2925, 2848, 2713, 2578, 1620, 1568, 1552, 1491, 1454, 1442,
1350, 1321, 1284, 1248, 1213, 1171, 1103, 1072, 1036, 1003, 955, 910, 860, 802, 756, 698, 677, 631, 567, 550,
513, 469. 1H- and 13C-NMR: see Table 8. EI-MS: 487 (19), 486 (57, [M ꢀ H2O]þ), 322 (6), 281 (9), 267
(5), 242 (12), 238 (16), 237 (100), 236 (82), 208 (13), 207 (55), 196 (15), 195 (61), 180 (9), 168 (8), 167
(17), 166 (15), 140 (8), 98 (19), 92 (13), 77 (23), 73 (13), 64 (18), 63 (7), 54 (9), 51 (21). ESI-MS (pos.):
543.1 (28, [M þ K]þ), 527.1 (81, [M þ Na]þ), 505.1 (100, [M þ H]þ). ESI-MS (neg.): 1029.2 (17, [2 M – 2 ·
H þ Na]ꢀ), 503.1 (100, [M ꢀ H]ꢀ). Anal. calc. for C30H20N2O4S (504.56): C 71.41, H 4.00, N 5.55, S 6.36;
found: C 71.67, H 4.26, N 5.37, S 6.20.

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Helvetica Chimica Acta – Vol. 95 (2012)
Table 8. 1H- and 13C-NMR Data ((D6)DMSO) of Compounds 13 and 14 (d in ppm)
Position
13d
13l
14h
14l
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
d(H)
d(C)
2
3
4
4a
5
6
7
8
8a
OH
–
–
–
–
7.96
7.14
7.48
7.26
–
165.3
103.0
172.5a)
118.2
124.6
120.9
130.8
115.0
138.5
–
–
–
–
8.07
7.39
7.60
6.67
–
165.0
103.7
166.7
115.3
124.2
123.2
133.0
116.3
140.4
–
–
–
–
–
8.16
7.24
7.60
7.41
–
162.6
100.3
168.3
119.7
124.6
120.8
131.0
114.1
139.7
–
–
–
–
–
8.17
7.18
7.36
6.40
–
162.8
100.1
169.4
119.5
125.3
121.1
130.7
115.1
140.9
–
n.o.
11.87
n.o.
n.o.
Substituent at N(1)
1
11.06
–
137.4
129.1
130.3
129.2
3.58
29.3
–
139.3
129.8
130.0
128.2
2,6
3,5
4
–
–
–
7.44
7.69
7.62
–
–
–
–
–
–
7.29
7.62
7.53
3,3’-Disulfanediylbis(4-hydroxy-1-methylquinolin-2(1H)-one) (14h). Isolated from Mh. Yellowish
crystals. M.p. 261 – 2638 (AcOEt). IR: 3094, 2945, 2904, 1617, 1607, 1574, 1540, 1504, 1446, 1419, 1401,
1337, 1316, 1269, 1248, 1208, 1170, 1118, 1077, 1041, 971, 944, 860, 834, 755, 686, 662, 618, 587, 537. 1H- and
13C-NMR: see Table 8. EI-MS: 381 (15), 380 (65, [M ꢀ S]þ), 207 (23), 176 (18), 175 (100), 174 (8), 162
(12), 147 (14), 146 (30), 134 (37), 133 (12), 132 (23), 116 (10), 105 (17), 104 (18), 91 (11), 78 (10), 77
(29), 64 (16), 51 (8). ESI-MS (pos.): 847.0 (21, [2 M þ Na]þ), 451.1 (18, [M þ K]þ), 435.1 (100, [M þ
Na]þ), 413.1 (24, [M þ H]þ). ESI-MS (neg.): 411.0 (100, [M ꢀ H]ꢀ). Anal. calc. for C20H16N2O4S2
(412.48): C 58.24, H 3.91, N 6.79, S 15.55; found: C 58.04, H 3.93, N 6.95, S 15.27.
3,3’-Disulfanediylbis(4-hydroxy-1-phenylquinolin-2(1H)-one) (14l). Isolated from Ml. Yellow crys-
tals. M.p. 241 – 2468 and then 320 – 3288 (benzene). IR: 3140, 3010, 2814, 1597, 1587, 1560, 1498, 1452,
1414, 1377, 1319, 1257, 1218, 1174, 1109, 1070, 1038, 910, 860, 835, 798, 766, 754, 700, 690, 671, 627, 580, 546.
1H- and 13C-NMR: see Table 8. EI-MS: 505 (22), 504 (62, [M ꢀ S]þ), 385 (6), 269 (22), 238 (25), 237
(100), 236 (68), 209 (7), 208 (10), 197 (10), 196 (84), 195 (37), 180 (11), 168 (7), 167 (32), 166 (9), 139
(6), 102 (6), 77 (30), 73 (15), 64 (66), 61 (11), 60 (18), 51 (16), 45 (15), 44 (38), 43 (26). ESI-MS (pos.):
575.1 (28, [M þ K]þ), 559.1 (100, [M þ Na]þ), 537.1 (81, [M þ H]þ). ESI-MS (neg.): 1093.1 (5, [2 M – 2 ·
H þ Na]ꢀ), 535.1 (100, [M ꢀ H]ꢀ). Anal. calc. for C30H20N2O4S2 (536.62): C 67.15, H 3.76, N 5.22, S 11.95;
found: C 67.26, H 3.68, N 5.31, S 11.63.
5. General Procedure for the Reaction of Compounds 4, 6, and 12 with NH4OH (Method D). To a
soln. of compound 4, 6, or 12 (50 mg) in EtOH (5 ml), 0.3 ml of NH4OH (35%) was added, and the
mixture was heated to 708 for 1 h. The solvent was evaporated, and the residue was crystallized from an
appropriate solvent or separated by CC. The following compounds were obtained: a) from 4e,
compounds 8e and 9e were obtained in yields of 20 and 31%, resp.; b) from 4g, compound 8g was
obtained in 50% yield; c) from 4i, compound 9i was obtained in 27% yield; d) from 4j, compounds 8j and
9j were obtained in yields 28 and 23%, resp.; e) from 6e, compound 8e was obtained in 79% yield; f) from
12d, compound 11d was prepared in 50% yield; g) from 12l, compound 11l was prepared in 61% yield.
Compounds 8j, 9e, 9i, and 9j were prepared merely by Method D. Compounds 8e, 8g, 9e, 11d, and 11l
were prepared also by Methods A, B, C, and are described in Sect. 3 of the Exper. Part.
1-(3-Ethyl-1,2-dihydro-2-oxo-1-phenylquinolin-4-yl)urea (8j). Prepared from 4j by Method D in
28% yield. Colorless crystals. M.p. 222 – 2258 and then 294 – 2978 (EtOH). IR: 3431, 3292, 3246, 2962,
2931, 2871, 1668, 1637, 1601, 1568, 1529, 1493, 1450, 1387, 1358, 1323, 1299, 1279, 1250, 1215, 1171, 1138,
1113, 1047, 881, 752, 700, 673, 642, 517. 1H- and 13C-NMR: see Table 6. EI-MS: 307 (5, Mþ), 291 (20), 290

Helvetica Chimica Acta – Vol. 95 (2012)
1371
(95), 289 (41), 275 (23), 264 (17), 263 (29), 262 (96), 261 (100), 249 (18), 247 (12), 236 (7), 235 (32), 234
(7), 218 (6), 217 /5), 205 (9), 204 (17), 167 (9), 140 (7), 137 (10), 131 (7), 116 (9), 115 (10), 109 (9), 103
(7), 102 (16), 96 (6), 91 (7), 77 (35), 65 (6), 58 (6), 51 (25). Anal. calc. for C18H17N3O2 (307.35): C 70.34,
H 5.58, N 13.67; found: C 70.23, H 5.74, N 13.51.
4-Amino-1,3-dimethylquinolin-2(1H)-one (9e). Prepared from 4e by Method D in 31% yield.
Colorless crystals. M.p. 168 – 1798 (AcOEt). For 9e, an m.p. of 1858 was reported in [27]. IR: 3413, 3363,
3244, 1655, 1624, 1599, 1564, 1421, 1342, 1228, 1132, 1095, 1049, 1034, 980, 939, 752, 746, 677, 625, 536, 459.
1H- and 13C-NMR: see Table 6. EI-MS: 189 (17), 188 (100, Mþ), 173 (19), 161 (10), 160 (17), 159 (51),
146 (9), 145 (22), 144 (8), 132 (8), 131 (9), 130 (10), 118 (8), 117 (9), 115 (6), 104 (7), 103 (6), 80 (15), 77
(16), 51 (8). Anal. calc. for C11H12N2O (188.23): C 70.19, H 6.43, N 14.88; found: C 69.95, H 6.40, N 14.71.
4-Amino-3-methyl-1-phenylquinolin-2(1H)-one (9i). Prepared from 4i by Method D in 27% yield.
Colorless crystals. M.p. 254 – 2558 (AcOEt). IR: 3469, 3332, 3224, 3070, 2912, 2854, 1655, 1603, 1577, 1558,
1504, 1491, 1448, 1421, 1358, 1333, 1319, 1307, 1286, 1234, 1198, 1167, 1124, 1111, 1074, 1003, 951, 918, 841,
796, 758, 702, 673, 652, 623, 592, 546, 515. 1H- and 13C-NMR: see Table 6. EI-MS: 251 (13), 250 (81, Mþ),
249 (100), 221 (11), 125 (8), 103 (5), 77 (12), 51 (7). Anal. calc. for C16H14N2O (250.30): C 76.78, H 5.64,
N 11.19; found: C 76.83, H 5.44, N 11.29.
4-Amino-3-ethyl-1-phenylquinolin-2(1H)-one (9j). Prepared from 4j by Method D in 23% yield.
Colorless crystals. M.p. 297 – 2998 (AcOEt). IR: 3463, 3329, 3222, 3062, 2960, 2949, 2924, 2864, 1655,
1620, 1603, 1577, 1558, 1504, 1444, 1419, 1360, 1340, 1323, 1284, 1261, 1230, 1155, 1117, 1074, 1063, 1022,
1003, 943, 858, 821, 781, 764, 752, 700, 677, 654, 619, 552, 517. 1H- and 13C-NMR: see Table 6. EI-MS: 265
(18), 264 (92, Mþ), 263 (50), 250 (19), 149 (100), 235 (9), 221 (10), 219 (6), 204 (6), 132 (8), 124 (12), 116
(5), 110 (11), 103 (5), 77 (13), 51 (7). Anal. calc. for C17H16N2O (264.32): C 77.25, H 6.10, N 10.60; found:
C 76.98, H 6.10, N 10.51.
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Received February 2, 2012