Synthesis and complexing properties of novel crown ethers and thiacrown ethers incorporating new heterocyclic moieties

Article abstract of DOI:10.1080/10426500903544280

The synthesis of some novel crown and thiacrown ethers via the reaction of 2,3-bis(4-hydroxyphenyl) or 2,3-bis(4-mercaptophenyl)quinoxalines and pyridopyridazine with diethylene and triethylene glycol ditosylate is described. The complexing ability of compounds 5b and 5h, as the representatives of both groups of compounds, with alkali and alkali earth metal cations were measured by the solvent extraction method. The results showed that crown ether 5b comparatively had more affinity towards the Mg²⁺ cation, while thiacrown ether 5h had greater affinity towards the Ca2+ cation. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426500903544280

This article was downloaded by: [Rensselaer Polytechnic Institute]
On: 17 September 2013, At: 02:49
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the
Related Elements
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gpss20
Synthesis and Complexing Properties
of Novel Crown Ethers and Thiacrown
Ethers Incorporating New Heterocyclic
Moieties
Mehdi Bakavoli a , Mohammad Rahimizadeh a , Esmaeel Rezaei-
Seresht b , Majid Mokaber Esfahani a & Parisa Ziaee a
a Department of Chemistry, School of Sciences, Ferdowsi University
of Mashhad, Mashhad, Iran
b Department of Chemistry, School of Sciences, Sabzevar Tarbiat
Moallem University, Sabzevar, Iran
Published online: 24 Sep 2010.
To cite this article: Mehdi Bakavoli , Mohammad Rahimizadeh , Esmaeel Rezaei-Seresht , Majid
Mokaber Esfahani & Parisa Ziaee (2010) Synthesis and Complexing Properties of Novel Crown Ethers
and Thiacrown Ethers Incorporating New Heterocyclic Moieties, Phosphorus, Sulfur, and Silicon and
the Related Elements, 185:10, 2152-2158, DOI: 10.1080/10426500903544280
To link to this article: http://dx.doi.org/10.1080/10426500903544280
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Phosphorus, Sulfur, and Silicon, 185:2152–2158, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500903544280
SYNTHESIS AND COMPLEXING PROPERTIES OF NOVEL
CROWN ETHERS AND THIACROWN ETHERS
INCORPORATING NEW HETEROCYCLIC MOIETIES
Mehdi Bakavoli,1 Mohammad Rahimizadeh,1
Esmaeel Rezaei-Seresht,2 Majid Mokaber Esfahani,1
and Parisa Ziaee1
1Department of Chemistry, School of Sciences, Ferdowsi University of Mashhad,
Mashhad, Iran
2Department of Chemistry, School of Sciences, Sabzevar Tarbiat Moallem
University, Sabzevar, Iran
The synthesis of some novel crown and thiacrown ethers via the reaction of 2,3-bis(4-
hydroxyphenyl) or 2,3-bis(4-mercaptophenyl)quinoxalines and pyridopyridazine with di-
ethylene and triethylene glycol ditosylate is described. The complexing ability of compounds
5b and 5h, as the representatives of both groups of compounds, with alkali and alkali earth
metal cations were measured by the solvent extraction method. The results showed that
crown ether 5b comparatively had more affinity towards the Mg2+ cation, while thiacrown
ether 5h had greater affinity towards the Ca2+ cation.
Keywords Complexing properties; crown ether; pyridopyridazine; quinoxalines; thiacrown
ether
INTRODUCTION
In the course of a program directed toward the synthesis of glycoluril-based receptors
for molecular recognition studies, we became interested in 4,4ꢁ-disubstituted benzyls, which
are valuable synthetic building blocks in the construction of molecular clips with crown
ether subunits.1 Crown ethers have been the focus of much attention since Pedersen’s studies
in the 1960s.2 These compounds are important molecular receptors for ionic recognition
and are currently used in analytical chemistry and biological model systems, as well as
in nuclear medicine.3,4 Likewise sulfur-substituted crown ethers, or thiacrown ethers, have
also observed tremendous advances over the past 20 years.5,6 These compounds are known
to coordinate with transition metal cations5,7 and soft alkaline and earth metal cations,8
whereas crown ethers prefer to coordinate with hard alkaline and earth metal cations.9 We
report in this article the synthesis of some novel crown and thiacrown ethers derived from
4,4ꢁ-disubstituted benzils and their complexing properties with alkali and alkali earth metal
Received 29 July 2009; accepted 7 December 2009.
Address correspondence to Mehdi Bakavoli, Department of Chemistry, School of Sciences, Ferdowsi Uni-
versity of Mashhad, Mashhad 91775-1436, Iran. E-mail: mbakavoli@yahoo.com
2152

NOVEL CROWN ETHERS AND THIACROWN ETHERS
2153
cations. The complexing abilities of both groups have been exemplified by a representative
of each group.
RESULTS AND DISCUSSION
The starting compound 1a, 4,4ꢁ-dihydroxybenzil, was prepared by demethyla-
tion of the commercially available 4,4ꢁ-dimethoxybenzil using HBr/HOAc mixture as a
demethylating agent.10 Compound 1b, 4,4ꢁ-dimercaptobenzil, was synthesized from 4,4ꢁ-
dichlorobenzil through an aromatic nucleophilic substitution reaction in the presence of
sodium hydrogensulfide in DMF.11 In the next step, the benzil derivatives 1a and 1b
were condensed with the aromatic diamines 2a–c to yield the heterocyclic compounds
3a–f (Scheme 1). Compound 1a is comparatively less reactive than 1b, since p-hydroxy
groups have a greater deactivating effect on the electrophilic nature of the carbonyl groups;
therefore a condensation reaction of 1a with diamines was performed under azeotropic
distillation to afford the cyclized products 3a–f (Scheme 1). The latter compounds were
reacted with ditosylates 4a and 4b under high dilution to obtain the crown and thiacrown
ethers 5a–l (Scheme 1). Spectral evidence and elemental analyses clearly confirmed the for-
mation of these products. For example, the 1H NMR spectrum of thiacrown ether 5g showed
the methylene protons as two triplets at 2.96 and 3.39 ppm (J = 6 Hz). The IR spectrum
was devoid of the S–H absorption band at 2520 cm−1 of the precursor, but showed a CH2
R
O
O
3
R
Y
N
3a; X= O, R= H, Y= CH
3b; X= O, R= H, Y=N
3c; X= O, R= Me, Y=CH
3d; X= S, R= H, Y= CH
3e; X= S, R= H, Y=N
3f; X= S, R= Me, Y=CH
Y
N
+
NH2
H2N
HX
XH
2
1
HX
XH
1a; X= O
1b; X= S
2a; R= H, Y= CH
2b; R= H, Y=N
2c; R= Me, Y=CH
OTs
TsO
n
O
K2CO3 / CH3CN
Reflux , 3 days
4
4a; n = 1
4b; n = 2
R
Y
5a; X= O, R= H, Y= CH, n = 1
5b; X= O, R= H, Y= CH, n = 2
5c; X= O, R= H, Y= N, n = 1
5d; X= O, R= H, Y= N, n = 2
5e; X= O, R= Me, Y= CH, n = 1
5f; X= O, R= Me, Y= CH, n = 2
5g; X= S, R= H, Y= CH, n = 1
5h; X= S, R= H, Y= CH, n = 2
5i; X= S, R= H, Y= N, n = 1
5j; X= S, R= H, Y= N, n = 2
5k; X= S, R= Me, Y= CH, n = 1
5l; X= S, R= Me, Y= CH, n = 2
N
N
X
O
X
n
5
Scheme 1

2154
M. BAKAVOLI ET AL.
absorption band at 1490 cm−1. The mass spectrum and elemental analysis also confirmed
the structure.
Extraction Ability
The complex formation ability of crown ethers with metal cations depends on several
factors, including cavity size of ligands, cation diameter, special distribution of the ring
binding sites, the character of the heteroatoms, and other factors.12 Crown and thiacrown
ethers containing phenyl groups are expected to interact with metal cations through their
heteroatoms, as well as π-electron density of the aromatic rings, and form complexes of
their own. The complexing capability can be affected by several factors such as the type
of heteroatom. Therefore, a quantitative comparison of complexation capability of 5b as
the representative of crown ethers 5a–f with that of the corresponding thiacrown ether 5h
towards few metal cations was carried out by the method described by Pedersen,13 and the
results are summarized in Table I. As can be seen from Table I, the extractabilities of both
crown ether and thiacrown ether for metal cations are varied and can be attributed to the
atomic radii of the cations. Na+ and Mg2+ cations, by having smaller atomic radii and being
harder compared to their counterparts in the periodic table of elements, K+ and Ca2+, have
more affinity toward crown ether 5b, while the softer cations K+ and Ca2+ show higher
affinity toward thiacrown ether 5h. Selective extraction of alkaline earth over alkali metal
ions is 2.7 (Mg+2:Na+ extraction ratio) for crown ether 5b, whereas this ratio for thiacrown
ether 5h is 8.0 (Ca+2:K+ extraction ratio). However, the high selectivity is attributed to
several factors, such as cavity size of the host, conformational behavior, cation radii, and
hardness and softness of donor and receptors atoms.
For high extraction efficiency of thiacrown ether 5h, rather than 5b, some contribution
to the complex’s stability may come from the π-interaction between Ca2+ and the electron-
rich aromatic rings in the crown ether framework. Although, a charge-transfer complex
between heterocyclic moiety and the counterion of the cationic guest may be another reason
for this observation. Further investigation on the heterocyclic ring’s effects in selectivity
and extraability of these compounds is in progress in our laboratory. According to this
preliminary study, the extraability of thiacrown ether 5h is greater than 5b. These two
ligands with the same number of donor atoms have different conformational behavior and
cavity size due to the differences in atomic radii and bond angles in sulfur and oxygen
Table I Extraction of metal picrates by crown ether 5b as compared to its thiacrown ether 5h [solvent system:
CH2Cl2:H2O (1:1)]
∗
∗
Crown
Cation
Ao
Ae
% Extraction
5b
Na+
K+
0.32051
0.32051
0.32051
0.32051
0.40594
0.40594
0.40594
0.40594
0.33365
0.32103
0.35608
0.32509
0.40767
0.42508
0.40800
0.55955
4.1
1.5
11.1
1.4
0.4
4.7
Mg2+
Ca2+
Na+
K+
5h
Mg2+
Ca2+
0.5
37.8
∗Ao and Ae are the absorbances of the aqueous layer before and after the extraction.

NOVEL CROWN ETHERS AND THIACROWN ETHERS
2155
atoms. Probably the binding site of receptors 5b and 5h is fitting well only to the small
cations, which may be clamped between the two aromatic walls.
In summary, we have synthesized several new crown ethers and thiacrown ethers
incorporating new heterocyclic moieties via a convenient route, and the extraction capabil-
ities of these compounds with few alkali and alkali earth metal cations were exemplified
by compounds 5b and 5h.
EXPERIMENTAL
Toluene was distilled from sodium benzophenon ketyl. MeCN was distilled from
CaCl2. CH2Cl2 and MeOH were distilled from CaH2. Silica gel 60 (0.040–0.063 mm,
Merck) was used for column chromatography. 4,4ꢁ-Dimethoxybenzil was purchased from
Merck. Oligoethylene glycol ditosylates (4a and 4b) were prepared according to the lit-
erature.14 Melting points were recorded on an Electrothermal type 9100 melting point
apparatus and are uncorrected. The IR spectra were obtained on a 4300 Shimadzu spec-
trometer. The 1H NMR (100 MHz) spectra were recorded on a Bruker AC 100 spectrometer.
Chemical shifts are reported in ppm downfield from TMS as internal standard; the coupling
constant J is given in Hertz. The mass spectra were scanned on a Varian Mat. CH-7 at
70 eV. Elemental analysis was performed on a Thermo Finnigan Flash EA microanalyzer.
General Procedure for the Synthesis of Dihydroxy Compounds 3a–c
A mixture of 4,4’-dihydroxybenzil (1a) (7.4 mmol, 1.73 g), aromatic diamine 2
(7.14 mmol), acetic acid (36 mL), and toluene (11 mL) was refluxed with a Dean–Stark
apparatus under N2 atmosphere for 12 h. After cooling, the mixture was poured into an ice-
water (144 mL) and HCl (7 mL) mixture. The precipitate was filtered off and recrystallized
from ethanol.
4-[3-(4-Hydroxyphenyl)-2-quinoxalinyl]phenol (3a). Yield 63%; mp > 300
◦C; IR (KBr): 609, 762, 735, 981, 1055, 1105, 1143, 1168, 1220, 1278, 1352, 1400, 1438,
1521, 1608, 1666, 1764, 3200, 3520 cm−1; 1H NMR (Acetone-d6): δ = 6.75 (d, 4H, J =
8 Hz), 7.34 (d, 4H, J = 8 Hz), 7.70 (dd, 2H, J = 2 Hz, J = 7 Hz), 8.05 (dd, 2H, J = 2 Hz,
J = 7 Hz), 8.69 (s, 2H, OH); M+ = 314; Anal. Calcd for C20H14N2O2: C, 76.42; H, 4.49;
N, 8.91. Found: C, 76.35; H, 4.33; N, 8.98.
4-[3-(4-Hydroxyphenyl) pyrido [2,3-b] pyrazinyl]phenol (3b). Yield 58%;
mp > 300 ◦C; IR (KBr): 607, 798, 835, 980, 1124, 1174, 1243, 1336, 1386, 1433, 1521,
1556, 1598, 1666, 3257, 3550 cm−1; 1H NMR (Acetone-d6): δ = 6.24 (d, 4H, J = 8 Hz),
6.89 (d, 4H, J = 8 Hz), 7.34 (dd, 1H, J = 2 Hz, J = 7 Hz), 8.02 (dd, 1H, J = 2 Hz, J =
7 Hz), 8.57 (dd, 1H, J = 4.2 Hz), 9.35 (s, 2H, OH); M+ = 315; Anal. Calcd for C19H13N3O2:
C, 72.37; H, 4.16; N, 13.33. Found: C, 72.35; H, 4.07; N, 13.21.
4-[3-(4-Hydroxyphenyl)-6-methyl-2-quinoxalinyl]phenol (3c). Yield 63%;
◦
mp > 300 C; IR (KBr): 617, 835, 981, 1172, 1240, 1344, 1512, 1558, 1606, 2875,
1
3520 cm−1; H NMR (Acetone-d6): δ = 2.55 (s, 3H, CH3), 6.82 (dd, 4H, J = 2 Hz, J =
7 Hz), 7.25–8.09 (m, 7H); M+ = 328; Anal. Calcd. for C21H16N2O2: C, 76.81; H, 4.91; N,
8.53. Found: C, 76.71; H, 4.78; N, 8.41.
General Procedure for the Synthesis of Dimercapto Compounds 3d–f
4,4ꢁ-Dimercaptobenzil (1b) (10 mmol) was refluxed in ethanol (100 mL) for 30 min.
Then a solution of aromatic diamine 2 (11 mmol) in ethanol (50 mL) was added dropwise,

2156
M. BAKAVOLI ET AL.
and the reflux was continued for 8 h. After cooling, water (300 mL) was added, and the
yellow solid was filtered off, washed with water, and recrystallized from ethanol.
4-[3-(4-Mercaptophenyl)-2-quinoxalinyl]thiophenol (3d). Yield 65%; mp
◦
1
176–179 C; IR (KBr): 609, 1111, 1350, 1393, 1660, 2520 cm−1; H NMR (CDCl3):
δ = 3.53 (s, 2H, SH), 7.23 (d, 4H, J = 7 Hz), 7.41 (d, 4H, J = 7 Hz), 7.79 (dd, 2H, J = 2
Hz, J = 7 Hz), 8.21 (dd, 2H, J = 2 Hz, J = 7 Hz); M+ = 346; Anal. Calcd for C20H14N2S2:
C, 69.36; H, 4.05; N, 8.09; S, 18.50. Found: C, 69.48; H, 3.89; N, 8.31; S, 18.32.
4-[3-(4-Mercaptophenyl)pyrido[2,3-b]pyrazinyl]thiophenol
(3e). Yield
63%; mp > 300 ◦C; IR (KBr): 823, 1095, 1323, 1392, 1456, 1588, 2520, 2864, 2919, 3419
cm−1; 1H NMR (CDCl3): δ = 3.54 (s, 2H, SH) 7.15–7.55 (m, 8H), 7.70 (dd, 1H, J = 2 Hz,
J = 7 Hz), 8.48 (dd, 1H, J = 2 Hz, J = 7 Hz), 9.16 (dd, 1H, J = 2 Hz, J = 7 Hz); M+ =
347; Anal. Calcd for C19H13N3S2: C, 65.70; H, 3.74; N, 12.10; S, 18.46. Found: C, 65.61;
H, 3.58; N, 12.37; S, 18.44.
4-[3-(4-◦Mercaptophenyl)-6-methyl-2-quinoxalinyl]thiophenol (3f). Yield
1
58%; mp158 C; IR (KBr): 815, 1183, 1330, 1589, 1630, 2540, 2930, 3423 cm−1; H
NMR (CDCl3): δ = 2.59 (s, 3H, CH3), 3.50 (m, 2H, SH), 7.20 (d, 4H, J = 8 Hz), 7.38 (d,
4H, J = 8 Hz), 7.53 (t, 1H, J = 8 Hz), 7.89 (s, 1H), 8.00 (d, 1H, J = 8 Hz); M+ = 360;
Anal. Calcd for C21H16N2S2: C, 70.00; H, 4.44; N, 7.78; S, 17.78. Found: C, 69.94; H,
4.26; N, 7.68; S, 18.12.
General Procedure for the Synthesis of Crown Ethers
and Thiacrown Ethers 5a–l
Ditosylate 4 (0.3 mmol) was added in small portions during a period of 12 h to a
refluxing mixture of 3 (0.3 mmol) and K2CO3 (0.14 g, 1 mmol) in dry MeCN (20 mL). The
reflux was continued for 36 h. Then the solvent was evaporated in vacuo, and the residue
was partitioned between aqueous NaOH (5%, 25 mL) and CH2Cl2 (25 mL). The organic
layer was washed with water (2 × 25 mL), dried (Na2SO4), and evaporated to dryness. After
column chromatography (eluent: CH2Cl2:MeOH, 98:2, v/v), compound 5 was obtained as
pure powder.
(2,3-Diphenylquinoxaline)-4ꢀ,4ꢀꢀ-dioxy diethylene glycol (5a). This com-
pound was ob◦tained according to the general procedure starting with 3a and 4a. Yield
53%; mp 230 C; IR (KBr): 883, 978, 1134, 1176, 1247, 1473, 1604, 1666, 1764, 2871,
3381 cm−1; 1H NMR (CDCl3): δ = 3.96 (t, 4H, J = 6 Hz), 4.18 (t, 4H, J = 6 Hz), 6.90 (d,
4H, J = 8 Hz), 7.45 (d, 4H, J = 8 Hz), 7.77 (dd, 2H, J = 4 Hz, J = 6 Hz), 8.13 (dd, 2H,
J = 4 Hz, J = 6 Hz); M+ = 384; Anal. Calcd for C24H20N2O3: C, 74.98; H, 5.24; N, 7.29.
Found: C, 74.95; H, 5.16; N, 7.32.
(2,3-Diphenylquinoxaline)-4ꢀ,4ꢀꢀ-dioxy triethylene glycol (5b). This com-
pound was obtained according to the general procedure starting with 3a and 4b. Yield
◦
60%; mp 187–190 C; IR (KBr): 675, 761, 737, 781, 928, 974, 1051, 1134, 1173, 1249,
1296, 1344, 1390, 1440, 1506, 1604, 1666, 1699, 1715, 1764, 2335, 2869 cm−1; 1H NMR:
(CDCl3) δ: 3.61 (s, 4H), 3.70 (t, 4H, J = 5 Hz), 4.05 (t, 4H, J = 5 Hz), 6.70 (d, 4H, J =
8Hz), 7.32 (d, 4H, J = 8 Hz), 7.55 (dd, 2H, J = 4 Hz, J = 7 Hz), 7.86 (dd, 2H, J = 4 Hz,
J = 7 Hz); M+ = 428; Anal. Calcd for C26H24N2O4: C, 72.88; H, 5.65; N, 6.54. Found: C,
72.85; H, 5.71; N, 6.63.
(2,3-Diphenylpyrido[2,3-b]pyrazine)-4ꢀ,4ꢀꢀ-dioxy diethylene glycol (5c).
This compound was obtained according to the general procedure starting with 3b and 4a.
Yield 32%; mp > 300 ◦C; IR (KBr): 673, 976, 1128, 1176, 1249, 1384, 1442, 1601, 1664,

NOVEL CROWN ETHERS AND THIACROWN ETHERS
2157
1724, 2871 cm−1; 1H NMR (CDCl3): δ = 3.95 (t, 4H, J = 4 Hz), 4.20 (t, 4H, J = 4 Hz),
6.88 (dd, 4H, J = 4 Hz), 7.43–7.63 (m, 5H), 8.48 (dd, 1H, J = 2 Hz, J = 8 Hz), 9.13 (dd,
1H, J = 2 Hz, J = 8 Hz); M+ = 385; Anal. Calcd for C23H19N3O3: C, 71.67; H, 4.97; N,
10.90. Found: C, 71.61; H, 4.81; N, 10.91.
(2,3-Diphenylpyrido[2,3-b]pyrazine)-4ꢀ,4ꢀꢀ-dioxy triethylene glycol (5d).
This compound was obtained according to the general procedure starting with 3b and
4b. Yield 48%; mp 210 ◦C; IR (KBr): 673, 979, 1592, 1664, 1726 cm−1; 1H NMR (CDCl3):
δ = 3.73 (s, 4H), 3.90 (t, 4H, J = 4 Hz), 4.15 (t, 4H, J = 4 Hz), 6.85 (dd, 4H, J = 4 Hz,
J = 7 Hz), 7.41–7.67 (m, 5H), 8.41 (dd, 1H, J = 2 Hz, J = 8 Hz), 9.11 (dd, 1H, J = 2 Hz,
J = 8 Hz); M+ = 429; Anal. Calcd for C25H23N3O4: C, 69.92; H, 5.40; N, 9.78. Found: C,
69.78; H, 5.18; N, 9.79.
(2,3-Diphenylquinoxaline)-6-methyl-4ꢀ,4ꢀꢀ-dioxy diethylene glycol (5e).
This compound was ◦obtained according to the general procedure starting with 3c and 4a.
Yield 54%; mp 130 C; IR (KBr): 835, 978, 1134, 1174, 1249, 1342, 1512, 1554, 1681,
2873, 3421 cm−1; 1H NMR (CDCl3): δ = 2.58 (s, 3H, CH3), 3.90 (t, 4H, J = 6 Hz), 4.15
(t, 4H, J = 6 Hz), 6.85 (dd, 4H, J = 2 Hz, J = 6 Hz), 7.15–8.11 (m, 7H); M+ = 398; Anal.
Calcd for C25H22N2O3: C, 75.36; H, 5.57; N, 7.03. Found: C, 75.31; H, 5.64; N, 6.97.
(2,3-Diphenylquinoxaline)-6- methyl-4ꢀ,4ꢀꢀ-dioxy triethylene glycol (5f).
This compound was obtained according to the general procedure starting with 3c and
◦
4b. Yield 44%; mp 236 C; IR (KBr): 979, 1132, 1176, 1244, 1512, 1606, 2868, 3448
cm−1; 1H NMR (CDCl3): δ = 2.95 (s, 3H, CH3), 3.56 (s, 4H), 3.78 (t, 4H, J = 6 Hz), 4.22
(t, 4H, J = 6 Hz), 6.88 (dd, 4H, J = 4 Hz, J = 8 Hz), 7.15–8.10 (m, 7H); M+ = 442; Anal.
Calcd for C27H26N2O4: C, 73.28; H, 5.92; N, 6.33. Found: C, 73.21; H, 5.79; N, 6.31.
(2,3-Diphenylquinoxaline)-4ꢀ,4ꢀꢀ-dithio diethylene glycol (5g). This com-
pound was obtained according to the general procedure starting with 3d and 4a. Yield 52%;
◦
mp > 300 C; IR (KBr): 665, 761, 784, 816, 923, 946, 1013, 1091, 1170, 1190, 1219,
1352, 1397, 1490, 1555, 1586, 1663, 2923 cm−1; 1H NMR (CDCl3): δ = 2.96 (t, 4H, J =
6 Hz), 3.39 (t, 4H, J = 8 Hz), 7.19 (d, 4H, J = 8 Hz), 7.36 (d, 4H, J = 8 Hz), 7.82 (dd,
2H, J = 4 Hz, J = 7 Hz), 8.20 (dd, 2H, J = 4 Hz, J = 7 Hz); M+ = 416; Anal. Calcd for
C24H20N2OS2: C, 69.20; H, 4.84; N, 6.72; S, 15.40. Found: C, 69.14; H, 4.77; N, 6.58; S,
15.44.
(2,3-Diphenylquinoxaline)-4ꢀ,4ꢀꢀ-dithio triethylene glycol (5h). This com-
pound was obtained according to the general procedure starting with 3d and 4b. Yield
41%; mp > 300 ◦C; IR (KBr): 665, 761, 784, 816, 923, 946, 1013, 1091, 1170, 1190, 1219,
1352, 1397, 1490, 1555, 1586, 1663, 2923 cm−1; 1H NMR (CDCl3): δ = 3.04 (t, 4H, J =
7 Hz), 3.45–3.8 (m, 8H), 7.32 (d, 4H, J = 12 Hz), 7.46 (d, 4H, J = 12Hz), 7.77 (dd, 2H,
J = 4 Hz, J = 7 Hz), 8.13 (dd, 2H, J = 4 Hz, J = 7 Hz); M+ = 460; Anal. Calcd for
C26H24N2O2S2: C, 67.80; H, 5.25; N, 6.08; S, 13.92. Found: C, 67.79; H, 4.92; N, 6.06; S,
14.14.
(2,3-Diphenylpyrido[2,3-b]pyrazine)-4ꢀ,4ꢀꢀ-dithio diethylene glycol (5i).
This compound was obtai◦ned according to the general procedure starting with 3e and 4a.
Yield 57%; mp 226–228 C; IR (KBr): 836, 1013, 1081, 1176, 1319, 1374, 1428, 1547,
1
1594 cm−1; H NMR (CDCl3): δ = 2.98 (t, 4H, J = 6 Hz), 3.41 (t, 4H, J = 8 Hz), 7.22
(d, 4H, J = 9 Hz), 7.37 (d, 4H, J = 9 Hz), 7.77 (dd, 1H, J = 4 Hz, J = 7 Hz), 8.55 (dd,
1H, J = 2 Hz, J = 7 Hz), 9.21 (dd, 1H, J = 2 Hz, J = 7 Hz); M+ = 417; Anal. Calcd for
C23H19N3OS2: C, 66.16; H, 4.59; N, 10.06; S, 15.36. Found: C, 66.09; H, 4.43; N, 9.94;
S, 15.40.

2158
M. BAKAVOLI ET AL.
(2,3-Diphenylpyrido[2,3-b]pyrazine)-4ꢀ,4ꢀꢀ-dithio triethylene glycol (5j).
This compound was obtained according to the general procedure starting with 3e and 4b.
◦
Yield 39%; mp 98–101 C; IR (KBr): 607, 727, 765, 794, 827, 973, 1011, 1032, 1094,
1189, 1242, 1333, 1386, 1442, 1541, 1592, 1653, 1717, 2361, 2855, 3420 cm−1; 1H NMR
(CDCl3): δ = 3.06 (t, 4H, J = 7 Hz), 3.6 (t, 8H, J = 7 Hz), 7.37 (d, 4H, J = 10 Hz), 7.49
(d, 4H, J = 10 Hz), 7.71 (dd, 1H, J = 4 Hz, J = 7 Hz), 8.52 (dd, 1H, J = 4 Hz, J = 7 Hz),
9.19 (dd, 1H, J = 2 Hz, J = 4 Hz); M+ = 461. Anal. Calcd for C25H23N3O2S2: C, 65.05;
H, 5.02; N, 9.10; S, 13.89. Found: C, 65.02; H, 4.94; N, 9.03; S, 13.93.
(2,3-Diphenylquinoxaline)-6-methyl-4ꢀ,4ꢀꢀ-dithio diethylene glycol (5k).
This compound was obtained according to the general procedure starting with 3f and
4a. Yield 63%; mp 255–260 ◦C; IR (KBr): 622, 740, 767, 799, 835, 925, 979, 1013, 1054,
1080, 1094, 1185, 1301, 1330,1348, 1395, 1427, 1495, 1548, 1596, 1621, 2931 cm−1; 1H
NMR (CDCl3): δ = 2.63 (s, 3H), 2.96 (t, 4H, J = 6 Hz), 3.36 (t, 4H, J = 8 Hz), 7.18 (d,
4H, J = 8 Hz), 7.33(d, 4H, J = 8 Hz), 7.64 (d, 1H), 7.96 (s, 1H), 8.07 (d, 1H, J = 8 Hz);
M+ = 430; Anal. Calcd for C25H22N2OS2: C, 69.73; H, 5.15; N, 6.51; S, 14.89. Found: C,
69.69; H, 5.13; N, 6.55; S, 14.87.
(2,3-Diphenylquinoxaline)-6-methyl-4ꢀ,4ꢀꢀ-dithio triethylene glycol (5l).
This compound was obtained according to the general procedure starting with 3f and
4b. Yield 51%; mp 250–255 ◦C; IR (KBr): 620, 664, 780, 816, 832, 911, 980, 1013, 1094,
1131, 1176, 1295, 1330, 1395, 1484, 1594, 2867 cm−1; 1H NMR (CDCl3):δ = 2.62 (s, 3H,
CH3), 3.04 (t, 4H, J = 10 Hz), 3.50–3.70 (m, 8H), 7.38 (t, 8H, J = 12 Hz), 7.60 (d, 1H, J =
9 Hz), 7.93 (s, 1H), 8.05 (d, 1H, J = 9 Hz); M+ = 474; Anal. Calcd for C27H26N2O2S2: C,
68.32; H, 5.25; N, 5.90; S, 13.51. Found: C, 68.36; H, 4.98; N, 6.01; S, 13.47.
REFERENCES
1. M. Rahimizadeh, E. Rezaei Seresht, M. Bakavoli, and M. Pordel, Can. J. Chem., 85, 964 (2007).
2. C. J. Pedersen, J. Am. Chem. Soc., 89, 7017 (1967).
3. G. W. Gokel, W. M. Leevy, and M. E. Weber, Chem. Rev., 104, 2723 (2004).
4. J. C. G. Bu¨nzli and C. Piguet, Chem. Soc. Rev., 34, 1048 (2005).
5. (a) S. R. Cooper, Acc. Chem. Res., 21, 141 (1988); (b) A. J. Blake and M. Schroder, Adv. Inorg.
Chem., 35, 1 (1990); (c) S. R. Cooper and S. C. Rawle, Struct. Bonding, 72, 1 (1990).
6. (a) J. Buter and R. M. Kellogg, Org. Synth., 65, 150 (1987); (b) R. E. Wolf Jr., J. R. Hartman,
L. A. Ochrymowycz, and S. R. Cooper, Inorg. Synth., 25, 122 (1989); (c) P. J. Blower and S. R.
Cooper, Inorg. Chem., 26, 2009 (1987).
7. (a) C. J. Pedersen, J. Org. Chem., 36, 254 (1971); (b) S. G. Murray and F. R. Hartley, Chem.
Rev., 81, 365 (1981).
8. (a) B. Russell, J. Org. Magn. Reson., 4, 433 (1972) (b) J. Meijer, P. Vermeer, H. D. Verkruijsse,
and L. Brandsma, Recl. Trav. Chim. Pays-Bas, 92, 1326 (1973); (c) R. C. Long and J. H. Goldstein,
J. Mol. Spectrosc., 40, 632 (1971); (d) K. K. Deb, J. E. Bloor, and T. C. Cole, Inorg. Chem., 10,
2428 (1972); (e) N. V. Bojkova and R. S. Glass, Tetrahedron Lett., 39, 9125 (1998).
9. (a) C. J. Pedersen, J. Am. Chem. Soc., 89, 2495 (1967); (b) H. K. Frensdorff, J. Am. Chem. Soc.,
93, 600 (1971); (c) N. S. Poonia, J. Am. Chem. Soc. 96, 1012 (1974); (d) R. M. Izatt, K. Pawlak,
and J. S. Bradshaw, Chem. Rev., 91, 1721 (1991).
10. C. R. Moylan, R. Wortmann, R. J. Twieg, and I. H. McComb, Chem. Mater., 5, 1499 (1993).
11. Y. Ding and A. S. Hay, Macromolecules, 29, 6386 (1996).
12. F. Dejong and D. N. Reihoult, Stability and Reaction of Crown Ether Complexes (Academic
Press, New York, 1981).
13. C. J. Pedersen, Federation Proceedings, 27, 1305 (1968).
14. M. Ouchi, Y. Inoue, T. Kanzaki, and T. Hakushi, J. Org. Chem., 49, 1408 (1984).