Synthesis of thieno[3,4-d]-1,3-dithiol-2-one derivatives

Article abstract of DOI:10.1016/j.tetlet.2009.03.225

A series of mono-substituted and bis-substituted derivatives of thieno [3,4-d]-1,3-dithiol-2-one were prepared through halogenation, chloromethylation, and subsequent nucleophilic substitution reactions. Compounds were characterized by NMR, FT-IR, and HRM

Full text of DOI:10.1016/j.tetlet.2009.03.225

Tetrahedron Letters 50 (2009) 3750–3752
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Tetrahedron Letters
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Synthesis of thieno[3,4-d]-1,3-dithiol-2-one derivatives
Xin Chen a, Ronald L. Elsenbaumer a,b,
*
a Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX 76019, USA
b Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX 76019, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of mono-substituted and bis-substituted derivatives of thieno [3,4-d]-1,3-dithiol-2-one were
prepared through halogenation, chloromethylation, and subsequent nucleophilic substitution reactions.
Compounds were characterized by NMR, FT-IR, and HRMS.
Received 24 February 2009
Accepted 31 March 2009
Available online 22 April 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Thieno[3,4-d]-1,3-dithiol-2-one
Halogenation
Chloromethylation
Substitution
Synthesis
1. Introduction
functionalization reactions occurred at 4 and/or 6 position(s) to
maintain the annulated structure of thieno[3,4-d]-1,3-dithiol-2-
Polythiophene and its derivatives are of great interest as con-
ductive polymers owing to their characteristic electrochemical,
electronic, and optical properties.1 The potential commercial appli-
cations include light-emitting diodes, smart windows, photovoltaic
devices, and field effect transistors (FETs).2 It has been recognized
that the electrical and optical properties strongly depend on their
structures. Recently, much attention has been focused on develop-
ment of thiophene-based metallopolymers.3 Thieno[3,4-d]-1,3-
dithiol-2-one (1) emerged as a possible building block for synthesis
of 2-D conductive metallopolymer or complex owing to its unique
structure and ease of converting into dithiolate ligands under basic
conditions to form metal-bis-dithiolene complex;4 Another
important aspect of the compound is the possibility of forming
tetrathiafulvalene (TTF) or 2-thieno[3,4-d]-1,3-dithiol-2-ylidene-
thieno[3,4-d]-1,3-dithiole (dithiophene-tetrathiafulvalene, DTTTF)
like compounds through direct coupling. TTF charge-transfer salts
are well known as good candidates for superconductive materi-
als.5,6 Therefore, the functionalization of 1 to afford key monomers
for either cross-coupling polymerization7 or two-step precursor
polymerization8–12 becomes a crucial step in the process of search-
ing high-performance conductive polymers.
one. These compounds might be good candidates to prepare con-
jugated polythiophene derivatives and/or thiophene-base
metallopolymers.
2. Results and discussion
Compound 1 was prepared by oxidation of thieno[3,4-d]-1,3-
dithiole-2-thione with mercury(II) acetate, in less than 20% overall
yield.13 A modified one-pot method based on the literature was
used in our laboratory and gave a 48% yield from 3,4-dibromothi-
ophene as starting material.13–15
Halogenation reaction of compound 1 with mild halogenated
reagents such as N-chlorosuccinimide (NCS), N-bromosuccini-
mide (NBS), and N-iodosuccinimide (NIS), can selectively func-
tionalize the
4 and/or 6 positions and give a variety of
halogenated products with fairly good yields and stability
(Scheme 1). Results of these reactions are listed in Table 1.
Dibrominated compound 2d was reported by direct bromination
reaction of compound 1 with Br2 in carbon tetrachloride, which
afforded 95% yield.16 Diiodinated compound 2f could be synthe-
sized through a two-step procedure, which involves treating
compound 1 with mercury acetate at room temperature to give
4,6-diacetoxymercuri-thieno[3,4-d]-1,3-dithiol-2-one (compound
2g), followed by iodination in dry acetonitrile to afford 2f with
an overall yield of 60% after column purification.
We report here synthesis of a series of thieno[3,4-d]-1,3-
dithiol-2-one derivatives through halogenation, chloromethyla-
tion, and subsequent nucleophilic substitution reactions. All
Among all bifunctional thiophene derivatives, 2,5-bis(chloro-
methyl)thiophene is regarded as a useful key compound toward
* Corresponding author. Tel.: +1 817 272 1021; fax: +1 817 272 2538.
E-mail address: elsenbaumer@uta.edu (R.L. Elsenbaumer).
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.03.225

X. Chen, R. L. Elsenbaumer / Tetrahedron Letters 50 (2009) 3750–3752
3751
O
EtO
P
O
P
O
Et
O
S
Et
O
OEt
S
S
S
S
CH3COOH/CHCl3
O
+
N-Halogensuccinimide
S
S
S
S
Y
X
S
S
O
P
OE
t
O
2a -2f
1
P
O
OE
Et
t
O
Et
Scheme 1. General procedure to prepare halogenated derivatives of thieno[3,4-d]-
S
1,3-dithiol-2-one.
4
Scheme 3. 4,40,6,60-Tetra(diethoxyphosphorylmethyl)-2-(thieno[3,4-d]-1,3-dithiol-2-
ylidene)thieno[3,4-d]-1,3-dithiole.
Table 1
Halogenated derivatives of thieno[3,4-d]-1,3-dithiol-2-one (1)
Compound
X
Y
Yield (%)
Mp (°C)
tion of 3a into various derivatives having different functional
groups, the results are summarized in Table 2. The coupling reac-
tion of 3a with triethyl phosphite gave an unique compound
4,40,6,60-tetra(diethoxyphosphorylmethyl)-2-(thieno[3,4-d]-1,3-
dithiol-2-ylidene)thieno[3,4-d]-1,3-dithiole (4) in 32% yield. The
compound possesses a core structure of DTTTF, which is shown
in Scheme 3.
2a
2b
2c
2d
2e
2f
Cl
Cl
Br
Br
I
H
Cl
H
Br
H
I
72
84
81
87
68
82
95–96
112–113
100–101
130–131
114–115
185–186
I
In summary, we have demonstrated the synthesis of thieno
[3,4-d]-1,3-dithiol-2-one derivatives through halogenation, chlo-
romethylation, and nucleophilic substitution reactions. The suc-
cessful synthesis of these thiophene-based entities might lead to
preparation of some unique conductive polymers, metallopoly-
mers, and/or TTF-system materials. The study of polymerization
of these derivatives to obtain conjugated conductive materials is
still under investigation in our lab. The results will be reported in
a timely manner.
the formation of various 2,5-bis-substituted thiophenes.17,18
The chloromethylation reaction of thieno[3,4-d]-1,3-dithiol-2-one
(1) proceeded similarly as the chloromethylation of thiophene,
and afforded 4,6-bis(chloromethyl)thieno[3,4-d]-1,3-dithiol-2-one
(3a) with good yields (58%). It can be readily converted into other
functionalized derivatives via nucleophilic reactions (Scheme 2).
Nucleophilic substitution reactions were explored in transforma-
O
O
O
S
S
S
S
S
S
S
CCl4
+
HCHO
+
HCl (gas)
50°C/4 hours
CH2Cl
ClH2C
Y'
X'
S
S
1
3a
3b-3k
Scheme 2. Synthesis of 4,6-bis(chloromethyl)thieno[3,4-d]-1,3-dithiol-2-one (3a) and its derivatives.
Table 2
4,6-Bis(chloromethyl)thieno[3,4-d]-1,3-dithiol-2-one (3a) and its nucleophilic derivatives
Compound
X0
Y0
Yield (%)
Mp (°C)
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
–CH2Cl
–CH2OH
–CHO
–CH2Cl
–CH2OH
–CHO
–CH2N(CH2CH3)2
–CH2Py+(Clꢀ)
–CH2OAc
57
91
82
37
95
68
60
97
85
95
75
78
83
38
68
108–113 (decomposed)
105–106
215–216
N/A (amber oil)
>250
119–120
54–55
98–100
N/A (amber gel)
>250
94–96
183–184
152–154
88–89
–CH2N(CH2CH3)2
–CH2Py+(Clꢀ)
–CH2OAc
–CH2OCH3
–CH2SC(S)OCH2CH3
–CH2SC(S)N(CH2CH3)2
–CH2P+(Ph)3(Clꢀ)
–CH2SPh
–CH2OCH3
–CH2SC(S)OCH2CH3
–CH2SC(S)N(CH2CH3)2
–CH2P+(Ph)3(Clꢀ)
–CH2SPh
–CH2S(O)Ph
–CH2S(O)Ph
–CH2OAc
–CH2S(O)Ph
–CH2SPh
–CH2Cl
–CH2Cl
–CH2OS(O)Ph
136–137

3752
X. Chen, R. L. Elsenbaumer / Tetrahedron Letters 50 (2009) 3750–3752
4. Kean, C. L.; Pickup, P. G. Chem. Commun. 2001, 815.
Acknowledgment
5. Skabara, P. J.; Berridge, R.; McInnes, E. J. L.; West, D. P.; Coles, S. J.; Hursthouse,
M. B.; Muellen, K. J. Mater. Chem. 2004, 14, 1964.
Financial support from the Robert A. Welch Foundation
(Y-1291) is sincerely appreciated.
6. Organic Superconductors; Ishiguro, T., Yamaji, K., Saito, G., Eds., 2nd ed.;
Springer: Berlin, Heidelberg, 1998.
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8. Kean, C. L.; Miller, D. O.; Pickup, P. G. J. Mater. Chem. 2002, 12, 2949.
9. Cheng, H.; Elsenbaumer, R. L. J. Chem. Soc., Chem. Commun. 1995, 1451.
10. Fu, Y.; Cheng, H.; Elsenbaumer, R. L. Chem. Mater. 1997, 9, 1720.
11. Jen, K. Y.; Maxfield, M.; Shacklette, L. W.; Elsenbaumer, R. L. J. Chem. Soc., Chem.
Commun. 1987, 309.
Supplementary data
Supplementary data (detailed experimental procedures and NMR
spectra of all new compounds) associated with this article can be
found, in the online version, at doi:10.1016/j.tetlet.2009.03.225.
12. Jen, K. Y.; Jow, T. R.; Eckhardt, H.; Elsenbaumer, R. L. Polym. Mater. Sci. Eng.
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References and notes
1. Handbook of Conductive Polymers; Skotheim, T. A., Elsenbaumer, R. L., Reynolds,
J. R., Eds., 2nd ed.; Marcel Dekker: New York, NY, 1997.
2. Handbook of Organic Conductive Molecules and Polymer; Nalwa, H. S., Ed.; John
Wiley & Sons: Chichester, UK, 1997; Vol. 4.
3. Pickup, P. G. J. Mater. Chem. 1999, 8, 1641.