Reaction of substituted 1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]-quinolin iodides with arylamines. Synthesis of novel 1,2-dithiolo[3,4-c]-quinolin-1-ylidene(aryl)amines and 10-(arylimino)-7,10-dihydro[1,2]dithiolo[3,4-c]-pyrrolo[3,2,1-ij]quinoline-4,5-diones

Article abstract of DOI:10.24820/ark.5550190.p010.140

A series of novel (8-R-7-R'-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-R - phenyl)amines were synthesized by reaction of 4,4-dimethyl-1-methylthio-4,5-dihydro[1,2]dithiolo[3,4- c]quinolin iodides with arylamines in an efficient manner. The Stolle type reaction of the obtained compounds with oxalyl chloride gave 2-R-3-R'-10-[(4(2)-R -phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4- c]pyrrolo[3,2,1-ij]quinoline-4,5-diones. The structure of the synthesized compounds were characterized by NMR spectroscopy, mass-spectrometry and elemental analyses.

Full text of DOI:10.24820/ark.5550190.p010.140

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Arkivoc 2017, iii, 269-278
Organic Chemistry
Reaction of substituted 1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]-quinolin
iodides with arylamines. Synthesis of novel 1,2-dithiolo[3,4-c]-quinolin-1-
ylidene(aryl)amines and 10-(arylimino)-7,10-dihydro[1,2]dithiolo[3,4-c]-
pyrrolo[3,2,1-ij]quinoline-4,5-diones
Svetlana M. Medvedeva,a Fedor I. Zubkov,b Kristina Yu. Yankina,b Dmitry G. Grudinin,b
and Khidmet S. Shikhaliev*a
aVoronezh State University, Universitetskaya Sq. 1, Voronezh, 394006, Russia
bPeoples' Friendship University of Russia, Miklukho-Maklaya St. 6, Moscow, 117198, Russia
Email: chocd261@chem.vsu.ru
Dedicated to Oleg Alekseevich Rakitin on the occasion of his 65th birthday
Received 04-19-2017
Accepted 06-12-2017
Published on line 08-07-2017
Abstract
A
series of novel (8-R-7-R’-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-R”-
phenyl)amines were synthesized by reaction of 4,4-dimethyl-1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-
c]quinolin iodides with arylamines in an efficient manner. The Stolle type reaction of the obtained compounds
with oxalyl chloride gave 2-R-3-R’-10-[(4(2)-R”-phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-
c]pyrrolo[3,2,1-ij]quinoline-4,5-diones. The structure of the synthesized compounds were characterized by
NMR spectroscopy, mass-spectrometry and elemental analyses.
S
Ar
I-
S
S
N
+
S
R
Ar NH2
S
R
R'
N
H
R'
N
H
Ar NH2
Ar
N
S
Ar
N
S
S
R
(COCl)2
S
R
N
R'
R'
N
H
O
O
(76-86%)
(69-81%)
Keywords: Condensed 1,2-dithiol-3-thiones, 1,2-dithiolo[3,4-c]quinoline-1-thione, arylamines, 1,2-dithiol-3-
imines, Stolle reaction, oxalyl chloride
DOI: https://doi.org/10.24820/ark.5550190.p010.140
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Introduction
Condensed 1,2-dithiol-3-thiones represent an important class of organic compounds due to their wide
spectrum of reactivity in diverse reaction types.1-4 In particular, the 1,2-dithiol-3-thiones (or their salts) react
with the N-nucleophiles with cycle cleavage and / or with substitution of one of the exo- or endocyclic sulfur
atoms.1-10 Basically, the reaction with primary aliphatic and aromatic amines tends not to be selective and
leads to a mixture of 1,2-dithiol-3-imines and 1,2-thiazol-3-thiones, which exist in the "dynamic isomerism"
due to transformation by Dimroth-type rearrangement.11-16 Although we did not find any information about
reactions of 4,5-dihydro-4,4-dimethyl-1H-1,2-dithiolo[3,4-c]quinoline-1-thiones 1 with amines, the reaction of
their methylthio-dithiolium salts 2 with arylamines has been described earlier.17 According to the author, the
salts 2a,b reacted with p-phenetidine in boiling ethanol with loss of a methyl mercaptan molecule to form a
substituted 1,2-dithiol-3-imines 3a,b.17 As a result of this reaction, only two products were obtained with
relatively low yields and their structure only being confirmed by elemental analysis. Later, one more
compound 3с was synthesized by a similar reaction of methylthio-dithiolium salt 2a with aniline. IR
spectroscopy was then used as an additional method in order to prove the structure.18 However, this data is
not sufficient to identify unequivocally the obtained products as 1,2-dithiol-3-imines 3a-c, and not as isomeric
3-isothiazol-thiones 4a-c (Scheme 1). Moreover, the low yields might be related to non-selectivity of the
reaction, proceeding either on the exo-atom of sulfur or on endo-atom. No information about the synthesis of
4,4-dimethyl-2-aryl-4,5-dihydroisothiazolo[5,4-c]quinoline-1(2H)-thione 4 has been found in the literature.
Although the possibility of dithiole cycle’s endo-sulfur substitution by a nitrogen atom has been shown,19 the
interaction of methylthio-dithiolium salt 2c with o-phenylenediamine yielding imidazathiazol 5 has been cited
as the only example (Scheme 1).
S
S
-
S
S
I
+
S
R
S
R
MeI
R'
N
H
1 a-c
R'
N
H
2 a-c
NH2
NH2
R"
NH2
known
R"
known
unknown
R"
NH2
R"
S
N
N
N
N
S
S
R
S
S
R
R'
N
H
N
H
R'
N
H
3a-c
2 R' = H; R = H (a)17, OEt (b)17, Me (c)
3 R' = H; R = H, R" = OEt (a)17; R = OEt, R" = OEt (b)17; R = R" = H (c)18
4a-c
5
Scheme 1. Examples of methylthio-dithiolium salts 2a-c reaction with arylamines.
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Thus, there is still no conclusive evidence that in the reaction of methylthio-dithiolium salts with
arylamines the attack of amino groups targets exclusively the exo-sulfur atom. Therefore, the exact
determination of the reaction products structure and chemical properties are of current interest.
Results and Discussion
In order to extend our studies of 1,2-dithiolo[3,4-c]quinoline-1-thione chemistry 20-24, we have carried out the
reactions of 1,2-dithiolothiones 1 and their methylthiodithiolium salts 2 with arylamines. In addition, we
optimized the conditions of the latter reaction, convincingly proved the structure of the resulting products and
studied their chemical properties in the reaction of acylation by oxalyl chloride.
Reaction of 1,2-dithiolothiones 1 and their methylthiodithiolium salts 2 with arylamines. We have found
that dithiolothiones 1b-c do not react with arylamines in the absence of basic catalysts. When an alcoholic or
aqueous solution of alkali was used, the reaction mixture turned into black tar. This is probably related to side
reactions with the dithiol cycle cleavage.17 Traces of the condensation product barely appeared in the reaction
mixture even after long refluxing (more than 20 hours) of equimolar amounts of reagents in alcohol in the
presence of excess pyridine or catalytic amounts of DMAP. Increasing of refluxing time (up to 100 hours) leads
to decomposition of the reaction mass. Due to the good leaving group, the side processes for the
corresponding iodides 2 were avoided. Thus, the optimal conditions for such interaction were refluxing of the
equimolar amounts of reagents in an absolute isopropyl alcohol and in the presence of a two-fold molar
excess of pyridine for 2-3 hours. It was found that the reaction proceeds selectively with the substitution of
the exo-atom of sulfur to form the earlier unknown (8-R-7-R’-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-
c]quinolin-1-ylidene)(4(2)-R”-phenyl)amines 3d-i with quantitative yields (Scheme 2). Interestingly, the
presence of bulky substituents in aryl amine, the position and the electronic properties of the substituent had
no significant effect on the reaction time or product yield. We could not engage the endo-atom of sulfur in the
reaction under any conditions. Increasing refluxing time up to 20 hours or using an excess of arylamine (up to
2.5 fold) leads to decomposition of the reaction mass, while increasing the temperature (by changing the
solvent to 1-butanol) results in decrease of product yield along with the decomposition of starting
iodomethylates 2b-c to the corresponding 1,2-dithiol-3-thiones 1b-c.
Our attempts to obtain 7-R’-8-R-4,4-dimethyl-2-(4(2)-R”-phenyl)-4,5-dihydroisothiazolo[5,4-c]quinoline-
1(2H)-thiones 4 by Dimroth-type rearrangement through the formation of intermediate ions 3'and 4' were
also unsuccessful (Scheme 2). We found that the 1,2-dithiol-3-imines fragment of compounds 3d-i was
resistant to a basic environment (treatment with aqueous alkali for 40 h) as well as to an acidic medium
(heating at 40-50 °C for 20 h in alcoholic solution with an excess of hydrochloric acid). The stability of the
dithiol cycle is obviously related to arylimino group polarity decline due to conjugation with condensed
dihydroquinolines cycle.
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R"
R"
S
R"
R"
I-
S
S
NH2
NH2
+
S
N
S
N
R
S
R
i-PrOH + pyridine,
reflux, 2-3 h
S
R
R'
N
H
2b-e
R'
N
H
R'
N
H
4
R"
R"
3d-i (69-81%)
S
N
N-
S+
S-
S+
R
R
R'
N
H
R'
N
H
4'
3'
R
R’
H
R”
R
R’
H
3d
OEt
OEt
Me
Me
2-OEt
b
OEt
Me
3e
3f
H
4-(4-Cl-C6H4)CH2O
4-COOEt
4-Ph
2c
2d
2e
H
H
OMe
Me
H
3g
3h
3i
H
Me
OMe
Me
H
4-OPentyl
2-Pr
Me
Scheme 2. Preparation of (8-R-7-R’-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-
R”-phenyl)amines 3d-i.
Reaction of imines 3d-i with oxalyl chloride. Earlier23, 24 we performed the annelation of pyrroledione
fragment to 2,3-dithiol[3,4-c]quinolin-1-thione in order to form a new polycondensed heterocyclic system –
10-thioxo-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-4,5-dione. In this paper, aiming to obtain
new derivatives of this system, we have carried out a Stolle-type reaction25, 26 of arylamines 3d-i with oxalyl
chloride. The reaction proceeded smoothly, similar to dithiolthiones 1, by refluxing the substrates in absolute
toluene for 1.5 -2 h without any catalyst, although the two-stage Stolle reaction requires the presence of Lewis
acids.25, 26 The hydrogen chloride, generated during acylation, catalyzes further cyclization of intermediate
chloroxalylamides 6’a-f. It was found that the presence of the substituent in position 7 of starting compound 3
does not create any steric hindrances for the cyclization. Thus, the new 2-R-3-R’-10-[(4(2)-R”-phenyl)imino]-
7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-4,5-diones 6a-f were obtained in high
yields (Scheme 3).
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Medvedeva, S. M. et al.
R"
R"
R"
N
N
N
S
S
S
S
S
R
(COCl)2
R
S
R
PhMe, reflux
2-3 h
N
R'
R'
N
R'
N
H
Cl
O
O
O
3d-i
O
6a-f (76-86%)
6'a-f
R
R’
H
H
H
H
H
R”
6a
OEt
OEt
Me
Me
OMe
Me
2-OEt
6b
6c
6d
6e
6f
4-(4-Cl-C6H4)CH2O
4-COOEt
4-Ph
4-OPentyl
2-Pr
Me
Scheme 3. Preparation of 2-R-3-R’-10-[(4(2)-R”-phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-
c]pyrrolo[3,2,1-ij]quinoline-4,5-diones 6a-f.
Structure confirmation. The structure of compounds 3 and 6 were unambiguously proved by 1H and 13C NMR
1
spectroscopy and by mass spectrometry. In H NMR spectra of compounds 3d-I, the signals of gem-dimethyl
and secondary amino group protons appear in their respective fields.20-22 The protons of arylimino fragments
along with the protons of quinoline cycle show their signals in the aromatic field of spectrum. It should be
noted that the arylimino-group, like thio-keto group of 2,3-dithiol[3,4-c]quinolin-1-thiones,23, 24 exerts the
anisotropic effect on the C(9)-H proton, shifting the corresponding signal in the weak field – up to 8.2-8.4 ppm.
The presence of the characteristic signal of the imino group carbon atom 12, 27 at 166-168 ppm in the 13C NMR
spectra of the obtained compounds and the absence of peaks in the region of 183-185 ppm, corresponding to
the signals of the thiocarbonyl group carbon atom 12, 27, have allowed us to assign them the structure of 1,2-
dithiol-3-imines 3d-i instead of isomeric isothiazol-3-thiones 4. The peaks of molecular ion-radicals of medium
and high intensity are observed in the mass spectra (EI) of imines 3d-i. The fragment ions of compounds 3d, f-
i, formed by cleavage of methyl radical from molecular ion-radicals, are the peaks possessing maximum
intensity (Irel =100%). This kind of elimination is characteristic for disintegration of molecular ions of
hydroquinoline derivatives with gem-dimethyl group in the second position. 28 As for compound 3e, it is the
fragment ion, formed by elimination of methyl and substituted benzyl radicals, which has the maximal
intensity (Irel =100%), and not the molecular ion-radical (Irel =87%). It is interesting to note that the spectra of
all synthesized compounds contain ion peaks of varying intensity (from Irel=5% to Irel=14%), formed by
sequential elimination of methyl radical and corresponding aryl-isocyanide molecule from molecular ion-
radicals, which confirms additionally the assigned structure. No secondary amino group proton signal is found
1
in the H NMR spectra of pyrroldiones 6a-f (comparing to starting compounds 3d-i), while a characteristic set
of aromatic protons signals (though reduced by one proton) is still observed in the corresponding area. The
13C-NMR spectra contain the signals of two carbon atoms (from carbonyl groups) at 161-164 ppm and 182-183
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Medvedeva, S. M. et al.
ppm. The mass spectra of compounds 6a-f reveal the peaks of molecular ion-radicals with intensity from low
(for 6a-e) to maximal (for 6f) (Irel=14-100%). Their fragmentation occurs mostly by simultaneous elimination of
methyl radical and CO molecule (for compounds 6a, c-f), preceded by substituted benzyl radical elimination in
the case of the compound 6b.
Conclusions
4,4-Dimethyl-4,5-dihydro-1H-[1,2] dithiolo[3,4-c]quinoline-1-thiones react with arylamines only in the form of
methylthiodithiolium salts at reflux in an alcoholic medium in the presence of pyridine, the reaction proceeds
selectively with the substitution of exo-atom of sulfur to give (8-R-7-R'-4,4-dimethyl-4,5-dihydro-1H-
[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-R"-phenyl)amines. 1,2-Dithiol-3-imine fragment of latest retains
stability and in the basic and in an acid medium at the expense of conjugation with a condensed
dihydroquinoline cycle, making it impossible isomerizing these compounds into 7-R'-8-R-4,4-dimethyl-2-(4(2)-
R"-phenyl)-4,5-dihydroisothiazolo[5,4-c]quinoline-1(2H)-thiones by the type Dimroth rearrangement. Reacting
the resulting compounds with oxalyl chloride proceeds by Stolle type reaction without additional catalyst and
leads to the formation of 2-R-3-R'-10-[(4(2)-R"-phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-
c]pyrrolo[3,2,1-ij]quinoline-4,5-diones in high yields even if there is of steric hindrance.
Experimental Section
1
General. Melting points were determined on a PTP-M apparatus. The H and 13C NMR spectra were recorded
on a Bruker AM-400 spectrometer in DMSO-d6 at 400 and 100 MHz, respectively. TMS was used as the
internal standard. Mass spectra were recorded on a Finnigan MAT Incos 50 instrument with direct
introduction of sample into the ion source at 100-150 °C, with EI ionization and accelerating voltage of 70 eV.
The results of elemental analysis for the obtained compounds correspond to calculated data (Perkin Elmer
2400). The reactions were monitored and the purity of the products were checked by TLC with Silufol UV-254
(silica gel STC-1A as the sorbent) using chloroform as the mobile phase. The starting 8-R-7-R’-4,4-dimethyl-1-
methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]quinoline iodides 2b-e were synthesized according to known
procedures.17
General procedure for the synthesis of (8-R-7-R’-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-
ylidene)(4(2)-R”-phenyl)amines (3d-i). A solution of iodides 2b-e (1 mmol) and arylamine (1 mmol) was
refluxed in a mixture of absolute isopropyl alcohol (10 mL) and pyridine (1.6 mL) for 2-3 hours until no more
evolution methyl mercaptan was observed. The solvent was removed using the rotary evaporator, the solid
product was crystallized from isopropyl alcohol.
(8-Ethoxy-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(2-ethoxyphenyl)amine (3d).
Yellow crystals (0.284 g, 69%); mp 145-146 °C (isopropyl alcohol); 1H NMR (400 MHz, DMSO-d6): δ 1.20 (t, 3 H,
J 7.3 Hz, CH3CH2Oquinol), 1.24 (t, 3 H, J 6.9 Hz, CH3), 1.38 (s, 6 H, 2CH3), 3.86 (q, 2 H, J 7.3 Hz, CH2Oquinol), 4.02 (q,
2 H, J 6.9 Hz, CH2O), 5.90 (br s, 1 H, NH), 6.66 (d, 1 H, J 8.4 Hz, H-6quinol), 6.70 (d, 1 H, J 8.4 Hz, H-7quinol), 6.92 -
6.95 (m, 2 H, Ar-H), 7.07 – 7.10 (m, 2 H, Ar-H), 8.33 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 15.2,
15.3, 27.7, 55.9, 64.05, 64.6, 111.3, 115.1, 115.2, 115.8, 119.2, 120.3, 122.0, 123.2, 126.2, 137.4, 141.9, 149.5,
151.0, 161.3, 167.5; MS (EI) m/z (%): 412 (M+, 65), 397 (100), 275 (10), 222 (6), 168 (17), 154 (10). Anal. Calcd.
for C22H24N2O2S2 (412.57): C, 64.05; H, 5.86; N, 6.79; S, 15.54 %. Found: C, 63.92; H, 5.72; N, 6.93; S, 12.68 %.
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(8-Ethoxy-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)[4-[(4-chlorobenzyl)oxy-
1
phenyl]amine (3e). Yellow crystals (0.372 g, 73%); mp 153-154 °C (isopropyl alcohol); H NMR (400 MHz,
DMSO-d6): δ 1.22 (t, 3 H, J 7.0 Hz, CH3), 1.37 (s, 6 H, 2CH3), 3.84 (q, 2 H, J 7.0 Hz, CH2O), 5.08 (s, 2 H, CH2), 5.90
(br s, 1 H, NH), 6.65 (d, 1 H, J 8.4 Hz, H-6quinol), 6.70 (d, 1 H, J 8.4 Hz, H-7quinol), 6.96 (d, 2 H, J 8.0 Hz, Ar-H), 7.05
(d, 2, J 8.3 Hz, Ar-H), 7.42 (d, 2 H, J 8.0 Hz, Ar-H), 7.47 (d, 2, J 8.3 Hz, Ar-H), 8.24 (s, 1 H, H-9quinol); 13C NMR (100
MHz, DMSO-d6): δ 15.35, 27.7, 55.8, 64.0, 69.4, 111.1, 115.1, 115.8, 116.8, 119.1, 121.4, 123.3, 128.95, 129.95,
133.0, 136.8, 137.4, 146.2, 150.95, 156.0, 161.1, 167.2; MS (EI) m/z (%): 509 (M+, 87), 494 (88), 397 (7), 384
(9), 369 (100), 319 (6), 244 (60), 228 (14), 216 (13), 199 (10), 173 (10). Anal. Calcd. for C27H25ClN2O2S2 (509.08):
C, 63.70; H, 4.95; N, 5.50; S, 12.60 %. Found: C, 63.59; H, 5.62; N, 5.38; S, 12.74 %.
(4,4,8-Тrimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4-ethoxycarbonylphenyl)amine (3f).
Yellow crystals (0.312 g, 76%); mp 220-221 °C (isopropyl alcohol); 1H NMR (400 MHz, DMSO-d6): δ 1.29 (t, 3 H,
J 7.2 Hz, CH3CH2), 1.39 (s, 6 H, 2CH3), 2.13 (s, 3 H, CH3), 4.28 (q, 2 H, J 7.2 Hz, CH2), 6.10 (br s, 1 H, NH), 6.65 (d,
1 H, J 8.1 Hz, H-6quinol), 6.87 (d, 1 H, J 8.1 Hz, H-7quinol), 7.12 (d, 2 H, J 7.8 Hz, Ar-H), 7.98 (d, 2, J 7.8 Hz, Ar-H),
8.34 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 14.7, 22.2, 27.8, 55.8, 61.05, 114.6, 118.0, 120.4, 123.6,
124.3, 125.8, 126.6, 129.8, 131.9, 141.2, 156.6, 161.6, 165.9, 168.4; MS (EI) m/z (%): 410 (M+, 37), 395 (100),
367 (28), 321 (4), 183 (6), 175 (15), 156 (15). Anal. Calcd. for C22H22N2O2S2 (410.55): C, 64.36; H, 5.40; N, 6.82;
S, 15.64 %. Found: C, 64.21; H, 5.51; N, 6.74; S, 15.50 %.
(4,4,8-Тrimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4-phenylphenyl)amine (3g). Yellow
crystals (0.335 g, 81%); mp 209-210 °C (isopropyl alcohol); 1H NMR (400 MHz, DMSO-d6): δ 1.39 (s, 6 H, 2CH3),
2.15 (s, 3 H, CH3), 6.10 (br s, 1 H, NH), 6.67 (d, 1 H, J 8.1 Hz, H-6quinol), 6.88 (d, 1 H, J 8.1 Hz, H-7quinol), 7.10 (d, 2
H, J 7.7 Hz, Ar-H), 7.32 (t, 1 H, J 7.4 Hz, Ph-H), 7.43 (t, 2 H, J 7.4 Hz, Ph-H), 7.65 (t, 2 H, J 7.4 Hz, Ph-H), 7.65 (d, 2
H, J 7.4 Hz, Ph-H),7.71 (d, 2, J 7.7 Hz, Ar-H), 8.42 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 21.2, 27.9,
55.75, 114.5, 118.2, 120.8, 123.5, 124.4, 125.8, 126.9, 127.7, 128.7, 129.4, 129.7, 137.1, 140.3, 141.2, 152.0,
160.8, 167.7; MS (EI) m/z (%): 414 (M+, 23), 399 (100), 220 (14), 213 (9), 199 (8), 156 (6). Anal. Calcd. for
C25H22N2S2 (414.59): C, 72.43; H, 5.35; N, 6.76; S, 15.47 %. Found: C, 72.56; H, 5.41; N, 6.63; S, 15.61 %.
(8-Methoxy-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4-pentyloxyphenyl)amine
(3h). Yellow crystals (0.312 g, 71%); mp 154-155 °C (isopropyl alcohol); 1H NMR (400 MHz, DMSO-d6): δ 0.86 (t,
3 H, J 7.3 Hz, CH3), 1.30 – 1.35 (m, 4 H, 2CH2), 1.37 (s, 6 H, 2CH3), 1.65 – 1.70 (m, 2 H, CH2CH2O), 3.32 (s, 3 H,
CH3O), .3.91 (t, 2 H, J 6.6 Hz, CH2O), 5.91 (br s, 1 H, NH), 6.67 (d, 1 H, J 8.4 Hz, H-6quinol), 6.71 (d, 1 H, J 8.4 Hz, H-
7
quinol), 6.93 - 6.97 (m, 4 H, Ar-H), 8.29 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 14.3, 22.3, 27.6, 27.7.
28.3, 29.0, 55.8, 56.0, 68.4, 110.3, 115.0, 115.1, 116.3, 119.1, 121.4, 123.3, 137.5, 145.6, 151.8, 156.6, 161.0,
166.8; MS (EI) m/z (%): 440 (M+, 35), 425 (100), 365 (7), 236 (8), 230 (22). Anal. Calcd. for C24H28N2O2S2
(440.62): C, 65.42; H, 6.41; N, 6.36; S, 14.55 %. Found: C, 65.28; H, 6.52; N, 6.24; S, 14.61 %.
(4,4,7,8-Tetramethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(2-propoxyphenyl)amine
(3i).
Yellow crystals (0.303 g, 74%); mp 165-166 °C (isopropyl alcohol); 1H NMR (400 MHz, DMSO-d6): δ 0.85 (t, 3 H,
J 7.7 Hz, CH3CH2), 1.37 (s, 6 H, 2CH3), 1.59 – 1.62 (m, 2 H, CH2), 2.04 (s, 3 H, CH3-7), 2.10 (s, 3 H, CH3-8), 3.91 (t,
2 H, J 6.3 Hz, CH2O), 5.96 (br s, 1 H, NH), 6.53 (s, 1 H, H-6quinol), 6.92 - 6.94 (m, 2 H, Ar-H), 7.06 – 7.09 (m, 2 H,
Ar-H), 8.41 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 10.8, 19.5, 20.2, 22.6, 27.8, 55.7, 70.2, 114.9,
115.6, 116.1, 120.35, 122.0, 123.2, 124.55, 125.0, 126.2, 137.0, 141.5, 142.1, 149.4, 159.3, 168.1; MS (EI) m/z
(%): 410 (M+, 40), 395 (100), 352 (5), 319 (5), 288 (14), 234 (9), 170 (8), 160 (15). Anal. Calcd. for C23H26N2OS2
(410.60): C, 67.28; H, 6.38; N, 6.82; S, 15.62 %. Found: C, 67.14; H, 6.51; N, 6.93; S, 15.75 %.
General procedure for the synthesis of 2-R-3-R’-10-[(4(2)-R”-phenyl)imino]-7,7-dimethyl-7,10-
dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-4,5-diones (6a-f). Oxalyl chloride (1,1 mmol) was added
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to a solution of 1,2-dithiol-3-imine 3d-i (1 mmol) in absolute toluene (50 mL) and refluxed for 1,5-2 hours
while the reaction progress was monitored by TLC. The solvent was removed using the rotary evaporator; the
solid product was crystallized from toluene.
2-Ethoxy-10-[(2-ethoxyphenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-
1
ij]quinoline-4,5-dione (6a). Dark red crystals (0.354 g, 76%); mp 166-167 °C (toluene); H NMR (400 MHz,
DMSO-d6): δ 1.21 (t, 3 H, J 7.2 Hz, CH3CH2Oquinol), 1.24 (t, 3 H, J 7.0 Hz, CH3), 1.95 (s, 6 H, 2CH3), 3.96 (q, 2 H, J
7.2 Hz, CH2Oquinol), 4.03 (q, 2 H, J 7.0 Hz, CH2O), 6.98 – 7.02 (m, 3 H, 2 Ar-H + 1 H-7quinol), 7.06 – 7.13 (m, 2 H, Ar-
H), 8.64 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 15.0, 15.2, 27.9, 61.05, 64.7, 64.8, 108.4, 115.2,
116.2, 117.0, 119.7, 119.9, 120.0, 121.95, 126.9, 140.9, 141.7, 149.7, 155.6, 158.3, 163.8, 166.0, 182.5 ; MS (EI)
m/z (%): 466 (M+, 67), 433 (28), 423 (100), 405 (8), 368 (7), 309 (5), 273 (8), 212 (21), 181 (15), 167 (20). Anal.
Calcd. for C24H22N2O4S2 (466.57): C, 61.78; H, 4.75; N, 6.00; S, 13.75 %. Found: C, 61.56; H, 4.62; N, 6.11; S,
13.52 %.
10-({4-[(4-Chlorobenzyl)oxy]phenyl}imino)-2-ethoxy-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo-
1
[3,2,1-ij]quinoline-4,5-dione (6b). Dark red crystals (0.456 g, 81%); mp 165-166 °C (toluene); H NMR (400
MHz, DMSO-d6): δ 1.25 (t, 3 H, J 7.0 Hz, CH3), 1.94 (s, 6 H, 2CH3), 3.97 (q, 2 H, J 7.0 Hz, CH2O), 5.09 (s, 2 H, CH2),
6.99 (s, 1 H, H-7quinol), 7.01 (d, 2 H, J 8.0 Hz, Ar-H), 7.06 (d, 2, J 8.4 Hz, Ar-H), 7.42 (d, 2 H, J 8.0 Hz, Ar-H), 7.47
(d, 2, J 8.4 Hz, Ar-H), 8.53 (s, 1 H, H-9quinol); 13C NMR (100 MHz, DMSO-d6): δ 15.0, 27.9, 40.9, 61.0, 64.8, 69.5,
108.5, 116.3, 116.9, 119.4, 120.05, 121.4, 128.95, 129.9, 133.0, 136.7, 141.6, 145.4, 153.6, 155.5, 156.4, 158.3,
163.8, 165.9, 182.5; MS (EI) m/z (%): 563 (M+, 26), 437 (87), 395 (10), 366 (8), 253 (25), 125 (100). Anal. Calcd.
for C29H23ClN2O4S2 (563.09): C, 61.86; H, 4.12; N, 4.97; S, 11.39 %. Found: C, 62.00; H, 4.21; N, 5.10; S, 11.43 %.
10-[(4-Ethoxycarbonylphenyl)imino]-2,7,7-trimethyl-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]-
quinoline-4,5-dione (6c). Dark red crystals (0.399 g, 86%); mp 232-233 °C (toluene); 1H NMR (400 MHz, DMSO-
d6): δ 1.30 (t, 3 H, J 7.4 Hz, CH3CH2), 1.96 (s, 6 H, 2CH3), 2.24 (s, 3 H, CH3), 4.29 (q, 2 H, J 7.4 Hz, CH2), 7.19 (d, 2
H, J 8.8 Hz, Ar-H), 7.28 (s, 1 H, H-7quinol), 8.02 (d, 2 H, J 8.8 Hz, Ar-H), 8.69 (s, 1 H, H-9quinol); 13C NMR (100 MHz,
DMSO-d6): δ 14.7, 21.2, 27.95, 61.0, 61.2, 100.0, 115.6, 116.1, 120.4, 120.5, 124.2, 127.2, 131.55, 131.9,
132.95, 145.3, 155.9, 158.4, 164.3, 165.8, 167.6, 182.5; MS (EI) m/z (%): 464 (M+, 14), 420 (100), 393 (5), 363
(6), 211 (5), 197 (5), 188 (11). Anal. Calcd. for C24H20N2O4S2 (464.56): C, 62.05; H, 4.34; N, 6.03; S, 13.80 %.
Found: C, 62.19; H, 4.37; N, 6.14; S, 13.68 %.
10-(Biphenyl-4-ylimino)-2,7,7-trimethyl-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-4,5-dione
1
(6d). Dark red crystals (0.393 g, 84%); mp 227-228 °C (toluene); H NMR (400 MHz, DMSO-d6): δ 1.96 (s, 6 H,
2CH3), 2.25 (s, 3 H, CH3), 7.15 (d, 2 H, J 8.0 Hz, Ar-H), 7.28 (s, 1 H, H-7quinol), 7.35 (t, 1 H, J 7.7 Hz, Ph-H), 7.45 (t,
2 H, J 7.7 Hz, Ph-H), 7.68 (t, 2 H, J 7.7 Hz, Ph-H), 7.75 (d, 2 H, J 8.0 Hz, Ph-H), 8.76 (s, 1 H, H-9quinol); 13C NMR
(100 MHz, DMSO-d6): δ 21.2, 27.9, 61.1, 115.8, 116.1, 120.4, 120.7, 124.1, 126.95, 127.8, 128.8, 129.5, 131.7,
132.9, 137.7, 140.1, 145.3, 151.15, 158.4, 163.5, 166.6, 182.6; MS (EI) m/z (%): 468 (M+, 73), 425 (100), 396
(8), 363 (6), 348 (6), 213 (14), 152 (33). Anal. Calcd. for C27H20N2O2S2 (468.59): C, 69.20; H, 4.30; N, 5.98; S,
13.69 %. Found: C, 69.33; H, 4.43; N, 6.11; S, 13.58 %.
2-Methoxy-7,7-dimethyl-10-{[4-(pentyloxy)phenyl]imino}-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-
1
ij]quinoline-4,5-dione (6e). Dark red crystals (0.390 g, 79%); mp 189-190 °C (toluene); H NMR (400 MHz,
DMSO-d6): δ 0.87 (t, 3 H, J 7.8 Hz, CH3), 1.30 – 1.35 (m, 4 H, 2CH2), 1.65 – 1.70 (m, 2 H, CH2CH2O), 1.94 (s, 6 H,
2CH3), 3.71 (s, 3 H, CH3O), .3.94 (t, 2 H, J 6.8 Hz, CH2O), 6.93 – 7.07 (m, 5 H, 4 Ar-H + 1 H-7quinol), 8.57 (s, 1 H, H-
9quinol); 13C NMR (100 MHz, DMSO-d6): δ 14.3, 22.3, 27.85, 28.2, 28.9, 56.6, 61.0, 68.5, 107.8, 116.3, 116.45,
117.0, 118.8, 120.05, 121.45, 141.7, 144.8, 156.4, 157.0. 158.3, 163.6, 165.4, 182.5; MS (EI) m/z (%): 494 (M+,
72), 451 (100), 422 (5), 274 (5), 239 (5), 190 (7). Anal. Calcd. for C26H26N2O4S2 (494.63): C, 63.13; H, 5.30; N,
5.66; S, 12.97 %. Found: C, 63.01; H, 5.17; N, 5.79; S, 13.11 %.
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2,3,7,7-Tetramethyl-10-[(2-propoxyphenyl)imino]-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-
4,5-dione (6f). Dark red crystals (0.362 g, 78%); mp 145-146 °C (toluene); 1H NMR (400 MHz, DMSO-d6): δ 0.85
(t, 3 H, J 7.3 Hz, CH3CH2), 1.59 – 1.62 (m, 2 H, CH2), 1.92 (s, 6 H, 2CH3), 2.10 (s, 3 H, CH3-8), 2.35 (s, 3 H, CH3-8),
3.92 (t, 2 H, J 6.3 Hz, CH2O), 6.95 – 7.01 (m, 2 H, Ar-H), 7.08 – 7.14 (m, 2 H, Ar-H), 8.77 (s, 1 H, H-9quinol); 13C
NMR (100 MHz, DMSO-d6): δ 10.7, 14.6, 18.8, 22.7, 27.7, 60.9, 70.65, 113.3, 114.6, 115.4, 120.1, 120.2, 122.0,
126.7, 131.7, 132.0, 138.1, 141.4, 145.3, 149.65, 158.2, 161.7, 166.7, 183.3; MS (EI) m/z (%): 464 (M+, 100),
431 (50), 420 (92), 379 (17), 350 (18), 317 (28), 285 (18), 244 (10), 173 (10). Anal. Calcd. for C25H24N2O3S2
(464.60): C, 64.63; H, 5.21; N, 6.03; S, 13.80 %. Found: C, 64.50; H, 5.31; N, 6.14; S, 13.94 %.
Acknowledgements
This publication was supported by the Ministry of Education and Science of the Russian Federation (the
Agreement number 02.a03.21.0008). The authors are grateful to Amanda Andrews-Wuthrich for revision of
the manuscript and valuable comments.
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