Facile and efficient synthesis of substituted 1,4-dithiafulvalenes from β-dicarbonyl compounds

Article abstract of DOI:10.1080/00397910701544646

A facile and efficient synthetic route to substituted 1,4-dithiafulvalenes has been developed. The precursors 2 may be easily prepared from the reactions of β-dicarbonyl compounds 1 with CS2 and 1,2,3-tribromopropane under mild conditions. The elimination

Full text of DOI:10.1080/00397910701544646

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Facile and Efficient Synthesis of Substituted
1,4‐Dithiafulvalenes from β‐Dicarbonyl
Compounds
Jiqing Zhang a , Yulong Zhao a , Dazhi Li a , Fushun Liang a & Qun Liu a
a Department of Chemistry , Northeast Normal University , Changchun,
China
Published online: 10 Sep 2007.
To cite this article: Jiqing Zhang , Yulong Zhao , Dazhi Li , Fushun Liang & Qun Liu (2007) Facile and Efficient
Synthesis of Substituted 1,4‐Dithiafulvalenes from β‐Dicarbonyl Compounds, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 37:18, 3077-3087, DOI:
10.1080/00397910701544646
To link to this article: http://dx.doi.org/10.1080/00397910701544646
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Synthetic Communicationsw, 37: 3077–3087, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701544646
Facile and Efficient Synthesis of Substituted
1,4-Dithiafulvalenes from b-Dicarbonyl
Compounds
Jiqing Zhang, Yulong Zhao, Dazhi Li, Fushun Liang,
and Qun Liu
Department of Chemistry, Northeast Normal University,
Changchun, China
Abstract: A facile and efficient synthetic route to substituted 1,4-dithiafulvalenes has
been developed. The precursors 2 may be easily prepared from the reactions of b-dicar-
bonyl compounds 1 with CS2 and 1,2,3-tribromopropane under mild conditions.
The elimination of HBr of 2 in basic media furnishes corresponding acetyl substituted
1,4-dithiafulvalenes 3 in 85–93% yields. The aldol condensation reaction of 2 with
various arylaldehydes affords alkenoyl substituted 1,4-dithiofulvalenes 4 in high to
excellent yields.
Keywords: aldol condensation, b-dicarbonyl compounds, 1,4-dithiafulvalene derivatives,
rearrangement of a double bond, synthesis
Over the past few decades, the utility of a-oxo ketene-(S,S)-acetals as versatile
intermediates in organic synthesis has been recognized, and a few review
papers have been presented by Dieter,[1] Hunjappa,[2] Kolb,[3] and
Yokoyama,[4] respectively, on their preparation, structure, and synthetic appli-
cations. During the course of our studies on the chemistry of a-oxo ketene-
(S,S)-acetals,[5] the easily available and structurally flexible a-alkenoyl
ketene-(S,S)-acetals[6] have proved to be potent as five-carbon 1,5-bielectro-
philic synthons in [5 þ 1] annulation reactions.[7] As part of the research on
Received July 7, 2006
Address correspondence to Fushun Liang, Department of Chemistry, Northeast
Normal University, Changchun 130024, China. E-mail: liangfs112@nenu.edu.cn
3077

3078
J. Zhang et al.
the functionalized ketene-(S,S)-acetals, we developed dithiafulvalene (DTF)
and tetrathiafulvalene (TTF) derivatives through convenient synthetic
routes, with the consideration that DTF, TTF, and their derivatives, as
strong electron donors,[8] exhibit unusual and fascinating optoelectronic prop-
erties and have found wide applications in the field of molecular conductors,
small band gap molecular semiconductors, and nonlinear optics.[9] In this
context, we have successfully synthesized
a heteroatom-substituted
expanded 1,3-dithiolan[5]radialene with the structural feature of 25-
membered carbocycle peripherally bearing five dihydrodithiafulvalene
rings.[10] More recently, novel acetylene-spaced TTFs were designed and syn-
thesized starting from a-acetyl ketene-(S,S)-acetals.[11] Generally, 1,4-dithia-
fulvalene derivatives were synthesized via Knoevenagel-type reaction of
dithiolium salt with active methylene compounds[12] or the reaction of dithio-
carboxylates with propargyl bromide under basic conditions.[13] However,
these methods suffer from harsh reaction conditions, complex procedures,
and/or low yields. In this article, we describe a facile and efficient method
for the preparation of 1,4-dithiafulvalene derivatives of types 3 and 4.
In the initial experiments, after treatment of pentane-2,4-dione 1a
(R ¼ COCH3) with CS2 (1.1 equiv) in the presence of K2CO3 (2.2 equiv) in
DMF for 1 h under ice bath, 1,2,3-tribromopropane was added to the
reaction mixture dropwise and stirred overnight at room temperature.
A white solid was obtained after pouring the reaction mixture into a large
amount of ice water. The only product was characterized as 3-(4-bromo-
methyl-[1,3]dithiolan-2-ylidene)-pentane-2,4-dione 2a, with an excellent
yield of 91%, on the basis of its spectra and analytical data (Scheme 1 and
Table 1, entry 1). In the following work, other a-dicarbonyl compounds
such as 1b (R ¼ 4-Cl-PhNHCO), 1c (R ¼ COOCH3), 1d (R ¼ CN), and 1e
(R ¼ PhCO) were subjected to the reaction sequence under the identical con-
ditions. As a result, the corresponding a-acetyl ketene-(S,S)-acetals 2b–e
were obtained in 80–85% yields (Table 1, entries 2–4). It was observed
1
from the H and 13C NMR spectra that each compound of 2b–e consists of
two regio-isomers, due to the introduction of the two different electron-with-
drawing groups.
Scheme 1.

Substituted 1,4-Dithiafulvalenes
3079
Table 1. Preparation of the precursors 2a–e to substituted 1,4-dithiafulvalenes
Entry
Substrates
R
Time (h)
Products
Yields (%)a
1
2
3
4
5
1a
1b
1c
1d
1e
COCH3
4.0
4.0
4.0
4.0
4.0
2a
2b
2c
2d
2e
91
83
85
80
81
4-Cl-PhNHCO
COOCH3
CN
COPh
aIsolated yields.
With the readily available precursors 2 at hand, we turned to study the
synthesis of 1,4-dithiafulvalene derivatives. The reaction of 2a and NaOH
was first investigated in EtOH at room temperature (Scheme 2). The corres-
ponding 1,4-dithiafulvalene derivative, 2-acetyl-methylene-1,3-dithiole (3a),
was produced with an excellent yield of 95% (Table 2, entry 1).
The formation of 3a is supposed to be via the elimination of the hydrobromide
under basic conditions to form the double bond, followed by the rearrange-
ment of the double bond.[13,14] In a similar way, acetyl substituted 1,4-dithia-
fulvalenes 3b–d were successfully obtained in good to excellent yields of
85–93% (Table 2, entries 2–4). The Same as that of 2b–e, two regio-
isomers exist in each product of 3b–e.
In a further extension of the research, the aldol condensation reactions of
2a with selected arylaldehydes in the presence of NaOH were performed
according to the known procedure (Scheme 3).[7] As a result, a series of
alkenoyl substituted 1,4-dithiafulvalenes 4aa–ah, were achieved in
excellent yields (85–93%) and short reaction times (2.0–3.0 h). Some of
the results are summarized in Table 3. The rearrangement of the double
bond was also observed during the condensation reactions, same as the
reactions described previously. Obviously, the present protocol provides a
straightforward and general pathway to introduce acetyl or alkenoyl functional
groups into the 2-methylene-1,3-dithioles. Also it provides a convenient way
to further modify the resulting substituted 1,4-dithiafulvalenes, for example,
to construct tetrathiafulvalene derivatives.[10,11,15]
Scheme 2.

3080
J. Zhang et al.
Table 2. Preparation of the 2-acetyl-methylene-1,3-dithiole 3a–e
Time (h) Products Yields (%)a
Entry Substrates
R
1
2
3
4
5
2a
2b
2c
2d
2e
CH3CO
1.0
3.0
1.0
2.0
2.5
3a
3b
3c
3d
3e
95
93
92
85
86
4-Cl-PhNHCO
CH3OCO
CN
PhCO
aIsolated yields.
Scheme 3.
On the basis of these results, a possible mechanism for the formation of
the precursors 2 is proposed as depicted in Scheme 4. In the presence of
potassium carbonate, compound 1 reacted with CS2 to give dithiolate B.
Then, one of the sulfur anions of B attacks at the side primary carbon atom
of 1,2,3-tribromopropane to afford intermediate C. Finally, the intramolecular
attack to the secondary carbon atom from the other sulfur anion leads to the
formation of the corresponding bromomethyl substituted 1,3-dithiolanes 2.
In summary, we have demonstrated here a facile and efficient synthetic
method for a wide range of 1,4-dithiafulvalene derivatives (i.e., acetyl substi-
tuted 1,4-dithiofulvalenes 3 and alkenoyl substituted 1,4-dithiafulvalenes 4)
Table 3. Preparation of the 2-(a,a0-dialkenoyl) methylene-1,3-dithioles 4aa–ah
Products
4a
Entry
Ar
Time (h)
Yields (%)a
1
2
3
4
5
6
7
8
C6H5
4-ClC6H4
4-FC6H4
2.0
3.0
2.5
2.0
2.0
2.5
2.5
3.0
4aa
4ab
4ac
4ad
4ae
4af
91
93
93
90
90
93
85
86
4-CH3C6H4
4-CH3OC6H4
4-NO2C6H4
2-Furanyl
2-Pyridyl
4ag
4ah

Substituted 1,4-Dithiafulvalenes
3081
Scheme 4. Proposed mechanism for the formation of precursors 2.
in high yields under mild conditions, from easily available substrates and
cheap reagents. Indeed, the present protocols provide straightforward and
effective pathways to construct substituted 1,4-dithiafulvalenes of types 3
and 4 in concise steps. Further work on the synthetic applications of the cor-
responding substituted 1,4-dithiofulvalenes is under way.
EXPERIMENTAL
All reagents were purchased from commercial sources and used without
treatment, unless otherwise indicated. The products were purified by
1
column chromatography over silica gel. H NMR and 13C NMR spectra
were recorded at 258C on Varian 500 MHz and 125 MHz instruments, respect-
ively, and TMS was the internal standard. IR spectra (KBr) were recorded on a
Magna-560 FTIR spectrophotometer in the range of 400–4000 cm21. Mass
spectra were recorded on Agilient 1100 LCMsD mass spectrometer. C, H, N,
elemental analyses were conducted with Bio-Rad Co’s elemental analytical
instrument.
General Procedure for the Preparation of 2 (with 2a as an Example)
To a solution of pentane-2,4-dione (10.1 mL, 100 mmol) and anhydrous
K2CO3 (30.1 g, 220 mmol) in DMF (150 mL), CS2 (6.7 mL, 110 mmol) was
added at room temperature. After 30 min, 1,2,3-tribromopropane was added
in one portion to the reaction mixture under an ice bath and stirred

3082
J. Zhang et al.
overnight at room temperature. A white solid was obtained after pouring the
reaction mixture into ice water (800 mL). The only product was characterized
as 2a with an excellent yield of 91%.
Data
3-(4-Bromomethyl-1,3-dithiolan-2-ylidene)-pentane-2,4-dione (2a)
White solid; mp 92–948C. IR (KBr): 2926, 1619, 1439, 1402, 1269, 1261,
885 cm21
.
1H NMR (500 MHz, CDCl3, 293 K, TMS): d ¼ 2.43 (s, 3H,
CH3), 2.46 (s, 3H, CH3), 3.46–3.50 (m, 2H), 3.57–3.62 (m, 1H), 3.66–3.69
(m, 1H), 4.02 ppm (m, 1H). Anal. calcd. for C9H11BrO2S2: C, 36.62; H,
3.76. Found: C, 36.91; H, 3.71.
2-(4-Bromomethyl-1,3-dithiolan-2-ylidene)-N-(4-chlorophenyl)-3-
oxobutanamide (2b)
Yellow solid; mp 137–1398C. IR (KBr): 3302, 2358, 1642, 1618, 1511, 1442,
1245, 818 cm21. 1H NMR (500 MHz, CDCl3, 293 K, TMS): d ¼ 2.48 (s, 3H,
CH3), 3.56–3.62 (m, 2H), 3.64–3.66 (m, 1H), 3.76–3.79 (m, 1H), 4.07 ppm
(m, 1H). Anal. calcd. for C14H13BrClNO2S2: C, 41.34; H, 3.22; N, 3.44.
Found: C, 41.51; H, 3.09; N, 3.50.
Ethyl 2-(4-(Bromomethyl)-1,3-dithiolan-2-ylidene)-3-oxobutanoate (2c)
White solid; mp 77–798C. IR (KBr): 2984, 1684, 1634, 1437, 1416, 1247,
1
1025 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d ¼ 1.39 (t, 3H,
CH3), 2.44 (s, 3H, CH3), 3.49 (m, 2H), 3.60 (m, 2H), 4.02 (m, 1H), 4.34
(m, 2H). Anal. calcd. for C10H13BrO3S2: C, 36.93; H, 4.03. Found: C,
36.91; H, 4.08.
2-(4-(Bromomethyl)-1,3-dithiolan-2-ylidene)-3-oxobutanenitrile (2d)
White solid; mp 121–1238C. IR (KBr): 3413, 2199, 1654, 1441, 1270,
609 cm21
.
1H NMR (500 MHz, CDCl3, 293 K, TMS): d ¼ 2.46 (s, 3H,
CH3), 3.55–3.58 (m, 2H), 3.68–3.71 (m, 1H), 3.90–3.92 (m, 1H),
4.25 ppm (m, 1H). Anal. calcd. for C8H8BrNOS2: C, 34.54; H, 2.90; N,
5.03. Found: C, 34.81; H, 2.88; N, 5.21.
2-(4-(Bromomethyl)-1,3-dithiolan-2-ylidene)-1-phenylbutane-1,3-
dione (2e)
White solid; mp 70–728C. IR (KBr): 3059, 2959, 2862, 1650, 1446, 1277,
1234, 813 cm21
.
1H NMR (500 MHz, CDCl3, 293 K, TMS): d ¼ 2.00

Substituted 1,4-Dithiafulvalenes
3083
(s, 3H, CH3), 3.41 (m, 2H), 3.62 (m, 2H), 4.06 ppm (m, 1H), 7.51 (m, 2H),
7.59 (t, 1H), 7.79 (m, 2H). Anal. calcd. for C14H13BrO2S2: C, 47.06;
H, 3.67. Found: C, 47.23; H, 3.62.
General Procedure for the Preparation of 3 (with 3a as an Example)
To a solution of 2a (295 mg, 1.0 mmol) in EtOH (10.0 mL), NaOH (40 mg,
1.0 mmol) was added in one portion. The reaction mixture was stirred at rt
for 1 h. After the starting material 2a was consumed as monitored by TLC,
the resulting mixture was then poured onto ice water (250 mL). The precipi-
tated solid was collected by filtration, washed with water (3 ꢀ 30 mL), and
dried in vacuo. The crude product was purified by flash chromatography
(silica gel, petroleum ether–diethyl ether ¼ 10:1) to give 3a as a yellow solid.
Data
3-(4-Methyl-1,3-dithiol-2-ylidene)pentane-2,4-dione (3a)
Yellow solid; mp 84–868C. IR (KBr): 3439, 2993, 1567, 1449, 1366, 1314,
1
1224, 1022, 970 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d 2.45
(s, 6H), 2.63 (s, 3H), 6.93 ppm (s, 1H). MS (EI) calcd. m/z 214.0, found
215.1 [(M þ 1)]þ. Anal. calcd. for C9H10O2S2: C, 50.44; H, 4.70. Found: C,
50.52; H, 4.76.
N-(4-chlorophenyl)-2-(4-methyl-1,3-dithiol-2-ylidene)-3-
oxobutanamide (3b)
Yellow solid; mp 188–1908C. IR (KBr): 3284, 1647, 1594, 1492, 1399, 1313,
1
1247, 1092, 829 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d 2.33
(s, 3H), 2.49 (s, 3H), 6.63 (s, 1H), 7.31 (d, J ¼ 8.5 Hz, 2H), 7.64
(d, J ¼ 8.5 Hz, 2H), 9.45 ppm (s, 1H). Anal. calcd. for C14H12ClNO2S2:
C, 51.61; H, 3.71; N, 4.30. Found: C, 51.28; H, 3.77; N, 4.23.
Ethyl 2-(4-Methyl-1,3-dithiol-2-ylidene)-3-oxobutanoate (3c)
White solid; mp 75–778C. IR (KBr): 3052, 2980, 2929, 1662, 1589, 1423,
1
1373, 1345, 1259, 1095, 1031 cm21. H NMR (300 MHz, CDCl3, 293 K,
TMS): d 1.40–1.43 (m, 3H), 2.40 (s, 3H), 2.58 (s, 3H), 4.33-4.41 (m, 2H),
6.80 ppm (q, 1H). MS (EI) calcd. m/z 244.1, found 267.3 [(M þ 23)]þ.
Anal. calcd. for C10H12O3S2: C, 49.16; H, 4.95. Found: C, 49.43; H, 4.82.
2-(4-Methyl-1,3-dithiol-2-ylidene)-3-oxobutanenitrile (3d)
Yellow solid; mp 130–1328C. IR (KBr): 3742, 3046, 2359, 2197, 1622, 1406,
1
1301 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d 2.42 (s, 3H), 2.46

3084
J. Zhang et al.
(s, 3H), 6.76 ppm (s, 1H). MS (EI) calcd. m/z 197.0, found 220.1 [(M þ 23)]þ.
Anal. calcd. for C8H7NOS2: C, 48.71; H, 3.58; N, 7.10. Found: C, 48.69; H,
3.53; N, 6.92.
2-(4-Methyl-1,3-dithiol-2-ylidene)-1-phenylbutane-1,3-dione (3e)
Yellow solid; mp 112–1148C. IR (KBr): 3062, 1598, 1583, 1560, 1446,
1
1360 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d1.92 (s, 3H), 2.45
(s, 3H), 6.86 (s, 1H), 7.62–7.63 (m, 2H), 7.44–7.47 ppm (m, 3H). Anal.
calcd. for C14H12O2S2: C, 60.84; H, 4.38. Found: C, 61.02; H, 4.23.
General Procedure for the Preparation of 4aa–ah (with 4aa as an
Example)
To a solution of 2a (295 mg, 1.0 mmol) and benzaldehyde (222.6 mg,
2.1 mmol) in EtOH (10.0 mL) at 08C, NaOH (200 mg, 5.0 mmol) was
added in one portion. The reaction mixture was stirred at 08C for 10 min,
followed by stirring at 258C for 0.5 h. After the starting material 2a was
consumed as indicated by TLC, the resulting mixture was then poured onto
ice water (250 mL) under stirring. The precipitated solid was collected by fil-
tration, washed with water (3 ꢀ 30 mL), and dried in vacuo to afford the
product 2a as a yellow solid.
Data
4-(4-Methyl-1,3-dithiol-2-ylidene)-1,7-diphenylhepta-1,6-diene-3,5-
dione (4aa)
Yellow solid; mp 197–1998C. IR (KBr): 1628, 1572, 1539, 1543, 1370, 1304,
1
1169 cm21. H NMR (500 MHz, CDCl3, 293 K, TMS): d 2.49 (s, 3H), 6.96
(s, 1H), 7.33 (d, J ¼ 8.0 Hz, 4H), 7.38 (d, J ¼ 16.0 Hz, 1H), 7.52 (m, 5H),
7.77 (d, J ¼ 16.0 Hz, 2H). MS (EI) calcd. m/z 390.1, found 391.4
[(M þ 1)]þ. Anal. calcd. for C23H18OS2: C, 70.74; H, 4.65. Found: C,
70.78; H, 4.62.
1,7-Bis(4-chlorophenyl)-4-(4-methyl-1,3-dithiol-2-ylidene)hepta-
1,6-diene-3,5-dione (4ab)
Yellow solid; mp 191–1938C. IR (KBr): 1740, 1628, 1560, 1491, 1455, 1370,
1224, 1093 cm21
.
1H NMR (600 MHz, CDCl3, 293 K, TMS): d ¼ 2.49
(s, 3H), 6.96 (s, 1H), 7.29 (d, J ¼ 8.0 Hz, 4H), 7.29 (d, J ¼ 16.0 Hz, 2H),
7.43 (d, J ¼ 8.0 Hz, 4H), 7.69 (d, J ¼ 16.0 Hz, 2H). Anal. calcd. for
C23H16Cl2OS2: C, 60.13; H, 3.51. Found: C, 60.28; H, 3.48.

Substituted 1,4-Dithiafulvalenes
3085
1,7-Bis(4-fluorophenyl)-4-(4-methyl-1,3-dithiol-2-ylidene)hepta-1,6-
diene-3,5-dione (4ac)
Yellow solid; mp 185–1878C. IR (KBr): 3068, 1629, 1576, 1544, 1508, 1451,
1418, 1230 cm21
.
1H NMR (600 MHz, CDCl3, 293 K, TMS): d ¼ 2.48
(s, 3H), 6.94 (s, 1H), 6.98 (m, 4H), 7.23 (d, J ¼ 16.0 Hz, 2H), 7.50 (m, 4H),
7.68 (d, J ¼ 16.0 Hz, 2H).
4-(4-Methyl-1,3-dithiol-2-ylidene)-1,7-dip-tolylhepta-1,6-diene-3,5-
dione (4ad)
Yellow solid; mp 189–1918C. IR (KBr): 3070, 1630, 1595, 1517, 1441, 1412,
1341, 1224 cm21. 1H NMR (400 MHz, CDCl3, 293 K, TMS): d ¼ 2.35 (s, 6H,
2 ꢀ Me), 2.46 (s, 3H), 6.90 (s, 1H), 7.12 (d, J ¼ 8.0 Hz, 4H), 7.29
(d, J ¼ 16.0 Hz, 2H), 7.43 (d, J ¼ 8.0 Hz, 4H), 7.75 (d, J ¼ 16.0 Hz, 2H).
MS (EI) calcd. m/z 418.1, found 419.2 [(M þ 1)]þ. Anal. calcd. for
C25H22O2S2: C, 71.74; H, 5.30. Found: C, 71.91; H, 5.24.
1,7-Bis(4-methoxyphenyl)-4-(4-methyl-1,3-dithiol-2-ylidene)hepta-
1,6-diene-3,5-dione (4ae)
Yellow solid; mp 187–1898C. IR (KBr): 3058, 2928, 2837, 1624, 1604, 1567,
1
1511, 1449, 1366, 1255 cm21. H NMR (600 MHz, CDCl3, 293 K, TMS):
d ¼ 2.46 (s, 3H), 3.82 (s, 6H, 2 ꢀ OMe), 6.84 (d, J ¼ 8.0 Hz, 4H), 6.89
(s, 1H), 7.22 (d, J ¼ 16.0 Hz, 2H), 7.48–7.49 (d, J ¼ 6.0 Hz, 4H), 7.73
(d, J ¼ 16.0 Hz, 2H). Anal. calcd. for C25H22O4S2: C, 66.64; H, 4.92.
Found: C, 66.81; H, 4.88.
4-(4-Methyl-1,3-dithiol-2-ylidene)-1,7-bis(4-nitrophenyl)hepta-1,6-
diene-3,5-dione (4af)
Yellow solid; mp 189–1918C. IR (KBr): 3070, 1630, 1595, 1517, 1441, 1412,
1341, 1224 cm21
.
1H NMR (600 MHz, CDCl3, 293 K, TMS): d ¼ 2.53
(s, 3H), 7.05 (s, 1H), 7.37–7.40 (m, 2H), 7.63–7.65 (m, 4H), 7.75–7.78
(m, 2H), 8.17–8.19 (m, 4H).
1,7-Di(furan-2-yl)-4-(4-methyl-1,3-dithiol-2-ylidene)hepta-1,6-diene-
3,5-dione (4ag)
Yellow solid; mp 179–1818C. IR (KBr): 3399, 2170, 1678, 1628, 1549, 1448,
1364, 1289 cm21
.
1H NMR (400 MHz, CDCl3, 293 K, TMS): d ¼ 2.45
(s, 3H), 6.45 (m, 2H), 6.64 (m, 2H), 6.89 (s, 1H), 7.18 (d, J ¼ 16.0 Hz, 2H),
7.42 (m, 2H), 7.50 (d, J ¼ 16.0 Hz, 2H). MS (EI) calcd. m/z 370.1, found
371.3 [(M þ 1)]þ. Anal. calcd. for C19H14O4S2: C, 61.60; H, 3.81. Found:
C, 61.35; H, 3.78.

3086
J. Zhang et al.
4-(4-Methyl-1,3-dithiol-2-ylidene)-1,7-di(pyridin-2-yl)hepta-1,6-diene-
3,5-dione (4ah)
Yellow solid; mp 182–1848C. IR (KBr): 3400, 3024, 1633, 1575, 1538, 1462,
1364, 1293, 1227 cm21. 1H NMR (600 MHz, CDCl3, 293 K, TMS): d ¼ 2.50
(s, 3H), 6.98 (s, 1H), 7.20 (m, 2H), 7.50 (m, 2H), 7.62 (m, 2H), 7.70
(d, J ¼ 16.0 Hz, 2H), 7.70 (d, J ¼ 16.0 Hz, 2H), 8.52 (m, 2H). MS (EI)
calcd. m/z 392.1, found 393.4 [(M þ 1)]þ. Anal. calcd. for C21H16N2O2S2:
C, 64.26; H, 4.11; N, 7.14. Found: C, 64.54; H, 4.05; N, 7.09.
ACKNOWLEDGMENT
This research was supported by the Key Grant Project of Chinese Ministry of
Education (10412), the National Natural Sciences Foundation of China
(20272008), and Science Foundation for Young Teachers of Northeast
Normal University (20060313).
REFERENCES
1. Dieter, R. K. Tetrahedron 1986, 42, 3029.
2. Junjappa, H.; Ila, H.; Asokan, C. V. Tetrahedron 1990, 46, 5423.
3. (a) Kolb, M. Synthesis 1990, 171; (b) Kolb, M. Synthesis 1997, 357.
4. Yokoyama, M.; Imamoto, T. Synthesis 1984, 797.
5. (a) Yin, Y.; Wang, M.; Liu, Q.; Hu, J.; Sun, S.; Kang, J. Tetrahedron Lett. 2005, 46,
4399; (b) Sun, S.; Zhang, Q.; Liu, Q.; Kang, J.; Yin, Y.; Li, D.; Dong, D. Tetrahe-
dron Lett. 2005, 46, 6271; (c) Dong, D.; Liu, Y.; Zhao, Y.; Qi, Y.; Wang, Z.;
Liu, Q. Synthesis 2005, 85; (d) Liu, Q.; Che, G.; Yu, H.; Liu, Y.; Zhang, J.;
Zhang, Q.; Dong, D. J. Org. Chem. 2003, 68, 9148; (e) Liu, Y.; Dong, D.;
Liu, Q.; Qi, Y.; Wang, Z. Org. Biomol. Chem. 2004, 2, 28; (f) Sun, S.; Liu, Y.;
Liu, Q.; Zhao, Y.; Dong, D. Synlett 2004, 1731.
6. (a) Samuel, R.; Nair, S. K.; Asokan, C. V. Synlett. 2000, 1804; (b) Joseph, B. K.;
Verghese, B.; Sudarsanakumar, C.; Deepa, S.; Viswam, D.; Chandran, P.;
Asokan, C. V. Chem. Commun. 2002, 736.
7. (a) Bi, X.; Dong, D.; Liu, Q.; Pan, W.; Zhao, L.; Li, B. J. Am. Chem. Soc. 2005,
127, 4578; (b) Dong, D.; Bi, X.; Liu, Q.; Cong, F. Chem. Commun. 2005, 3580;
(c) Bi, X.; Dong, D.; Li, Y.; Liu, Q. J. Org. Chem. 2005, 70, 10886;
(d) Zhao, L.; Liang, F.; Bi, X.; Sun, S.; Liu, Q. J. Org. Chem. 2006, 71, 1094.
´
8. For reviews, see (a) Segura, J. L.; Martın, N. Angew. Chem., Int. Ed. 2001, 40,
1372; (b) Fourmigue, M.; Batail, P. Chem. Rev. 2004, 104, 5379; (c) Rovira, C.
Chem. Rev. 2004, 104, 5289; (d) Nielsen, M. B.; Lomholt, C.; Becher, J. Chem.
Soc. Rev. 2000, 29, 153.
9. (a) Ferraro, J. R.; Williams, J. M. Introduction to Synthetic Electrical Conductors;
Academic Press: New York, 1987; p. 1; (b) Kagoshima, S.; Nagasawa, H.;
Sambongi, T. One Dimensional Conductors; Springer Verlag: Berlin, 1987;
p. 1; (c) Saito, G.; Kagoshiwa, S. The Physics and Chemistry of Organic Super-
conductors; Springer Verlag: London, 1990; p. 1.

Substituted 1,4-Dithiafulvalenes
3087
10. Zhao, Y.-L.; Liu, Q.; Zhang, J.-P.; Liu, Z.-Q. J. Org. Chem. 2005, 70, 6913.
11. Zhao, Y.-L.; Zhang, W.; Zhang, J.-Q.; Liu, Q. Tetrahedron Lett. 2006, 47, 3157.
12. (a) Lozac’h, N.; Stavaux, M. Adv. Heterocycl. Chem. 1980, 27, 151;
´
´
(b) Andreu, R.; Cerdan, M. A.; Garın, J.; Orduna, J. Arkivoc 2004, 4, 32.
13. Dalgaard, L.; Jensen, L.; Lawesson, S.-O. Tetrahedron 1974, 30, 93.
14. Sakai, K. Chem. Pharm. Bull. 1963, 11, 752.
15. (a) Yamashita, Y.; Tomura, M.; Zaman, M. B.; Imaeda, K. Chem. Commun. 1998,
1657; (b) Sugimoto, T.; Awaji, H.; Sugimoto, I.; Misaki, Y.; Kawase, T.;
Yoneda, S.; Yoshida, Z.; Kobayashi, T.; Anzai, H. Chem. Mater. 1989, 1, 535.