A simple synthesis of angular anthrathiophenediones via acetylenic derivatives of anthraquinone

Article abstract of DOI:10.1055/s-2004-829187

Condensation of 2-alkynyl-1-chloro- and 1-alkynyl-2-chloroanthraquinones with Na₂S under mild conditions afforded anthra[1,2-b]thiophene-6,11- diones and anthra[2,1-b]thiophene-6,11-diones, respectively. A variety of angular anthrathiophenedion

Full text of DOI:10.1055/s-2004-829187

PAPER
2131
A Simple Synthesis of Angular Anthrathiophenediones via Acetylenic
Derivatives of Anthraquinone
Angular
r
A
nthrath
e
iophenedio
n
nes via
A
cet
a
ylenic
D
erivative
s
of
Anthraquinone. Ivanchikova, Nadezhda I. Lebedeva, Mark S. Shvartsberg*
Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
Fax +7(383)2342350; E-mail: shvarts@kinetics.nsc.ru
Received 24 February 2004; revised 24 May 2004
We supposed that vic-alkynylchloroanthraquinones could
be appropriate acetylenic precursors of anthrathiophene-
diones. In anthraquinone, a chlorine atom irrespective of
its position possesses a high nucleofugal lability.18 In vic-
Abstract: Condensation of 2-alkynyl-1-chloro- and 1-alkynyl-2-
chloroanthraquinones with Na2S under mild conditions afforded an-
thra[1,2-b]thiophene-6,11-diones and anthra[2,1-b]thiophene-6,11-
diones, respectively. A variety of angular anthrathiophenediones
was synthesized by this method. The acetylenic precursors were alkynylchloroanthraquinones it is additionally activated
prepared by a modified procedure of the Sonogashira reaction.
by an acetylenic substituent and readily substituted by nu-
cleophiles.19 On the other hand, the triple bond in these
Key words: quinones, alkynes, cross-coupling, ring closure, sulfur
compounds has an enhanced electrophilicity and is capa-
ble of interacting with a nucleophile as well.7,19 One
would expect that these particular properties of alkynyl-
Heterocyclic derivatives of quinones are of importance as
chloroanthraquinones would allow us to annulate the an-
biologically active substances and technical materials.
thraquinone nucleus by a thiophene ring using Na2S as the
simplest heterocyclizing agent.
Many condensed quinoid compounds including nitrogen-
and oxygen-containing rings are known. There is less in-
formation about such compounds with a sulfur-containing
heterocycle.
Indeed, we have found that acetylenes 1a–f bearing a
chlorine atom in position 1 react easily with an excess of
Na2S in 95% ethanol at 80 within 10–20 min to give an-
thra[1,2-b]thiophene-6,11-diones 2a–f in 57–90% yields
(Scheme 1).
At the same time, introduction of an S-heterocyclic frag-
ment can determine the character of biological activity of
a quinoid compound,1 reduce side-effects of a drug pre-
serving its basic action,2 impart new properties to techni-
cal materials or improve their quality.3,4 Also, the
presence of a sulfur-containing substructure in com-
pounds which do not belong to quinones often determine
their pharmacological properties.5,6 The above reasons
prompted us to develop a method for the annulation of an-
thraquinone by a thiophene ring. To our knowledge, gen-
eral methods for the synthesis of anthrathiophenediones
have not yet been described.
R
R
Cl
O
O
O
O
S
Na2S
EtOH
1 a-f
2 a-f
a: R = H
b: R = Ph
c: R = CMe2OH
e: R = CH2OH
f: R =
Earlier, we reported the synthesis of condensed quinoid
structures including pyrrole, furan, pyridine, pyridazine,
pyrazole, pyran and diazepin rings, which was based on
acetylenic derivatives of anthraquinone and naphtho-
quinone as key intermediates.7–12 In this work we used the
same approach for the synthesis of an anthrathiophenedi-
one system. Recently, a method for the synthesis of sub-
stituted benzo[b]thiophenes by cyclization of ortho-
(methylthio)alkynyl- and ortho-(benzylthio)alkynylben-
zenes under the action of electrophilic agents was elabo-
rated.6,13 However, its extension to derivatives of
anthraquinone is complicated by the limited availability
of corresponding sulfides. Other methods for formation of
benzothiophenes from acetylenic precursors are not suffi-
ciently general.14–17
d: R = CH(OH)(i-Pr)
Scheme 1
1-Alkynyl-2-chloroanthraquinones 3a–c,g having the
halogen atom in position 2, have also been shown to con-
dense similarly to 1 with Na2S and under the same condi-
R
R
O
O
O
O
S
Cl
Na2S
EtOH
3 a-c,g
4 a-c,g
a: R = H
b: R = Ph
c: R = CMe2OH
g: R = Bu
SYNTHESIS 2004, No. 13, pp 2131–2134
Advanced online publication: 30.07.2004
x
x.
x
x
.
2
0
0
4
DOI: 10.1055/s-2004-829187; Art ID: T02304SS
© Georg Thieme Verlag Stuttgart · New York
Scheme 2

2132
I. D. Ivanchikova et al.
PAPER
O
Cl
O
Cl
O
O
Cl
R
I
KOH
(7b-f)
CR
HC
(from 1c)
5
O
O
1 b-f
O
O
1 a
R
I
O
Cl
Cl
Cl
(7b,c)
KOH
HC CR
CuC CBu
(from 3c)
(for 3g)
O
6
3 b,c,g
O
O
3 a
a:
e:
R = H
R = CH2OH
b: R = Ph
R =
f:
c:
R = CMe2OH
g:
R = Bu
d: R = CH(OH)(i - Pr)
Scheme 3
carefully added. The obtained suspension of the diazonium salt was
added stepwise into a solution of CuCl (2.32 g, 23.3 mmol) in concd
HCl (80 mL) and stirred at 20 °C for 40 min and at 70 °C for 40 min.
The resulting mixture was stored overnight at r.t. The product was
filtered off, washed with H2O, dried and chromatographed on SiO2
tions. The yields of anthra[2,1-b]thiophene-6,11-diones
4a–c,g are 64–97% (Scheme 2).
1
It is noteworthy, that in the H NMR spectra of anthra-
thiophenediones 4 the signal of H in the b-position of the in toluene.
thiophene ring, which is brought together spatially with
the carbonyl group, is shifted to lower field with respect
to that of the similar H in spectra of compounds 2
(Dd = 1.3–1.4).
Yield of chloroiodoanthraquinone 5: 6.80 g (80.5%); mp 188–
189 °C (benzene).22
2-Chloro-1-iodoanthraquinone (6)
1-Amino-2-chloroanthraquinone (7.75 g, 30.0 mmol) was diazo-
tized by NaNO2 (8.20 g, 120.0 mmol) in H2SO4 (96%; 50 mL) at
20 °C. The resulting solution was slowly added with agitation to a
solution of KI (16.60 g, 100.0 mmol) in H2O (400 mL) at 0–5 °C
and then heated to 90–100 °C. After cooling, the formed precipitate
was filtered off, washed with H2O and dried. The product was puri-
fied by flash chromatography on Al2O3 in benzene.
The key acetylenes 1b–f and 3b,c were synthesized by
cross-coupling of 1-chloro-2-iodo- (5) and 2-chloro-1-io-
doanthraquinone (6) with corresponding terminal acety-
lenes 7b–f in aqueous dioxane in the presence of Na2CO3,
Pd(PPh3)2Cl2 and CuI9,20 (Scheme 3).
In our opinion, this modified procedure of the Sonogash-
ira reaction is the best method for the introduction of acet-
ylenic substituents into quinones. Acetylene 3g was
prepared by condensing the iodide 6 with cuprous butyl-
acetylide in pyridine. Chloroethynylanthraquinones 1a
and 3a were obtained from tertiary alcohols 1c and 3c by
the Favorsky retro-reaction.20
Yield of chloroiodoanthraquinone 6: 8.85 g (79.7%); mp 167–
168 °C (benzene).22
vic-Alkynylchloroanthraquinones 1b–f, 3b,c; General Proce-
dure
To a stirring solution of vic-chloroiodoanthraquinone 5 or 6 (5
mmol) in dioxane (60 mL) at 60 °C under Ar were added succes-
sively terminal acetylene 7 (7.5 mmol), Pd(PPh3)2Cl2 (40 mg, 0.06
mmol), CuI (20 mg, 0.10 mmol) and aq Na2CO3 (7.5 mmol; 30 mL)
preheated to 70–80 °C. The mixture was refluxed with stirring for
5–20 min, cooled, diluted with CHCl3 (200 mL), washed with H2O
(3 × 200 mL) and dried (MgSO4). The solvent was evaporated under
reduced pressure. The residue was purified by flash chromatogra-
phy (silica gel; toluene or CHCl3) and recrystallized (toluene–hex-
ane mixture) to give 1 or 3.
Thus, the cyclocondensation of available vic-alkynylchlo-
roanthraquinones with Na2S is a convenient method for
the synthesis of angular anthrathiophenediones.
1H NMR spectra were recorded on a Bruker DPX-200 (200 MHz)
spectrometer in CDCl3 at 25 °C using TMS as an internal standard.
IR spectra were determined with an UR-20 spectrometer in CHCl3.
Mps were measured on a Boetius micro mp hot stage apparatus and
were uncorrected. The course of the reactions was monitored by
TLC on Silufol UV 254 plates.
1-Chloro-2-phenylethynylanthraquinone (1b)
Yield: 85%, mp 193.5–194 °C.19
1-Chloro-2-(3-hydroxy-3-methylbutynyl)anthraquinone (1c)
Yield: 84%, mp 168–168.5 °C.
IR: 1690 (C=O), 2240 (C≡C), 3605 (OH) cm–1.
1H NMR: d = 1.70 (s, 6 H, Me), 7.83 (d, 1 H, J = 8.1 Hz, H-3), 7.75–
7.90 (m, 2 H, H-6,7), 8.26 (d, 1 H, J = 8.1 Hz, H-4), 8.20–8.35 (m,
2 H, H-5,8).
1-Chloro-2-iodoanthraquinone (5)
To a solution of 1-amino-2-iodoanthraquinone21 (8.00 g, 22.9
mmol) in H2SO4 (96%; 56 mL) at 20 °C was slowly added a suspen-
sion of NaNO2 (7.90 g, 114.5 mmol) in H2SO4 (34.5 mL) cooled to
10 °C. The mixture was stirred for 20 min at r.t., poured onto ice
(250 g), and then urea (5.70 g, 95.0 mmol) in H2O (32 mL) was
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Angular Anthrathiophenediones via Acetylenic Derivatives of Anthraquinone
2133
Anal.Calcd for C19H13O3Cl: C, 70.27; H, 4.03; Cl, 10.91. Found: C,
70.40; H, 3.95; Cl, 10.78.
1-Chloro-2-ethynylanthraquinone (1a)
1-Chloro-2-(3-hydroxy-3-methylbutynyl)anthraquinone (1c) (1.45
g, 4.5 mmol) and powdered KOH (1.00 g, 17.9 mmol) in absolute
benzene (100 mL) were refluxed with stirring for 45 min. The mix-
ture was filtered, benzene was removed under reduced pressure. 1-
Chloro-2-ethynylanthraquinone (1a) was purified by flash chroma-
tography (alumina; toluene) and by crystallization (toluene–hexane
mixture).
1-Chloro-2-(3-hydroxy-4-methylpentynyl)anthraquinone (1d)
Yield: 47%, mp 160–161.5 °C.
IR: 1690 (C=O), 2235 (C≡C), 3400 br, 3615 (OH) cm–1.
1H NMR: d = 1.10 (d, 3 H, J = 6.7 Hz, Me), 1.13 (d, 3 H, J = 6.7 Hz,
Me), 1.95–2.10 (m, 2 H, CHMe2, OH), 4.45–4.55 (m, 1 H, CHO),
7.75–7.85 (m, 2 H, H-6,7), 7.83 (d, 1 H, J = 8.0 Hz, H-3), 8.25 (d, 1
H, J = 8.0 Hz, H-4), 8.25–8.35 (m, 2 H, H-5,8).
Yield: 0.90 g (73%); mp 211–212 °C.
IR: 1690 (C=O), 2130 (C≡C), 3310 (C≡CH) cm–1.
Anal. Calcd for C20H15O3Cl: C, 70.90; H, 4.46; Cl, 10.46. Found: C,
70.78; H, 4.46; Cl, 10.40.
1H NMR: d = 3.67 (s, 1 H, HC≡C), 7.75–7.90 (m, 2 H, H-6,7), 7.91
(d, 1 H, J = 8.1 Hz, H-3), 8.20–8.35 (m, 2 H, H-5,8), 8.28 (d, 1 H,
J = 8.1 Hz, H-4).
1-Chloro-2-(3-hydroxypropynyl)anthraquinone (1e)
Yield: 47%; mp 197.5–199 °C.
IR: 1690 (C=O), 2240 (C≡C), 3400 br, 3620 (OH) cm–1.
1H NMR: d = 4.67 (s, 2 H, CH2), 7.75–7.90 (m, 3 H, H-3,6,7), 8.20–
8.30 (m, 3 H, H-4,5,8).
Anal. Calcd for C16H7O2Cl: C, 72.06; H, 2.65; Cl, 13.29. Found: C,
71.98; H, 2.84; Cl, 13.09.
2-Chloro-1-ethynylanthraquinone (3a)
Compound 3a was prepared under the same conditions as 1-chloro-
2-ethynylanthraquinone (1a), but from 2-chloro-1-(3-hydroxy-3-
methylbutynyl)anthraquinone (3c).
Anal. Calcd for C17H9O3Cl: C, 68.82; H, 3.06; Cl, 11.95. Found: C,
68.66; H, 3.02; Cl, 11.79.
Yield: 31%; mp 244–245 °C.
1-Chloro-2-(1-cyclohexenylethynyl)anthraquinone (1f)
Yield: 73%, mp 194–195 °C.
IR: 1690 (C=O), 2210 (C≡C) cm–1.
1H NMR: d = 1.55–1.80 (m, 4 H, 4¢, 5¢-CH2), 2.10–2.40 (m, 4 H, 3¢,
6¢-CH2), 6.35–6.45 (m, 1 H, 2¢-CH), 7.75–7.85 (m, 2 H, H-6,7), 7.99
(d, 1 H, J = 8.3 Hz, H-3), 8.20–8.30 (m, 2 H, H-5,8), 8.35 (d, 1 H,
J = 8.3 Hz, H-4).
IR: 1690 (C=O), 2120 (C≡C), 3320 (C≡CH) cm–1.
1H NMR: d = 3.97 (s, 1 H, HC≡C), 7.70–7.90 (m, 2 H, H-6,7), 7.87
(d, 1 H, J = 8.4 Hz, H-3), 8.25–8.45 (m, 2 H, H-5,8), 8.27 (d, 1 H,
J = 8.4 Hz, H-4).
Anal. Calcd for C16H7O2Cl: C, 72.06; H, 2.65; Cl, 13.29. Found: C,
72.18; H, 2.59; Cl, 13.26.
Angular Anthrathiophene-6,11-diones 2a–f and 4a–c,g; Gener-
al Procedure
Anal. Calcd for C22H15O2Cl: C, 76.19; H, 4.36; Cl, 10.22. Found: C,
75.94; H, 4.30; Cl, 9.86.
To a stirring suspension of anhyd Na2S (3.5 mmol) in 95% EtOH
(35 mL) at 60–70 °C was added vic-alkynylchloroanthraquinone 1
or 3 (1.0 mmol). The reaction mixture was refluxed and stirred for
10–20 min and poured into H2O (300 mL). The product was extract-
ed with CHCl3 (3 × 100 mL), the combined organic extracts were
washed with H2O (2 × 100 mL), dried (MgSO4) and evaporated in
vacuo. The resulting residue was purified by flash chromatography
(silica gel or alumina; toluene or CHCl3) and crystallized (toluene–
hexane mixture).
2-Chloro-1-phenylethynylanthraquinone (3b)
Yield: 78%, mp 196.5–197 °C.19
2-Chloro-1-(3-hydroxy-3-methylbutynyl)anthraquinone (3c)
Yield: 79%, mp 183.5–184.5 °C.
IR: 1690 (C=O), 2240 (C≡C), 3400 br, 3615 (OH) cm–1.
1H NMR: d = 1.76 (s, 6 H, Me), 2.97 (br s, 1 H, OH), 7.70–7.80 (m,
2 H, H-6,7), 7.80 (d, 1 H, J = 8.5 Hz, H-3), 8.20–8.30 (m, 2 H, H-
5,8), 8.20 (d, 1 H, J = 8.5 Hz, H-4).
Anthra[1,2-b]thiophene-6,11-dione (2a)
Yield 67%; mp 216–217 °C.
1H NMR: d = 7.48 (d, 1 H, J = 5.5 Hz, H-3), 7.90 (d, 1 H, J = 5.5
Hz, H-2), 7.75–7.85 (m, 2 H, H-8,9), 8.18 [d, 1 H, J = 8.2 Hz, H-
4(5)], 8.30–8.35 [m, 3 H, H-5(4),7,10].
Anal. Calcd for C19H13O3Cl: C, 70.27; H, 4.03; Cl, 10.92. Found: C,
70.20; H, 4.04; Cl, 11.03.
2-Chloro-1-(hex-1-ynyl)anthraquinone (3g)
A mixture of 2-chloro-1-iodoanthraquinone (6) (0.74 g, 2 mmol)
and cuprous butylacetylide (0.45 g, 3 mmol) in pyridine (50 mL)
was stirred at 60 °C under Ar for 1 h, diluted with CHCl3 (150 mL),
washed with aq HCl (18%; 100 mL) and H2O up to pH 7 and dried
(MgSO4). After evaporation of the solvent in vacuo the residue was
chromatographed (silica gel; toluene). The product was crystallized
(toluene–hexane mixture).
Anal. Calcd for C16H8O2S: C, 72.71; H, 3.05; S, 12.13. Found: C,
72.52; H, 2.94; S, 11.86.
2-Phenylanthra[1,2-b]thiophene-6,11-dione (2b)
Yield: 90%; mp 287–288 °C.
1H NMR: d = 7.40–7.55 (m, 3 H, 3 HPh), 7.65 (s, 1 H, H-3), 7.80–
7.90 (m, 4 H, 2 HPh, H-8,9), 8.12 [d, 1 H, J = 8.2 Hz, H-4(5)], 8.30–
8.40 [m, 3 H, H-5(4),7,10].
Yield of 3g: 0.51 g (78%); mp 123–124 °C.
IR: 1680 (C=O), 2230 (C≡C) cm–1.
1H NMR: d = 0.99 (t, 3 H, J = 7.0 Hz, Me), 1.50–1.85 (m, 4 H, b-,
g-CH2), 2.68 (t, 2 H, J = 7.0 Hz, a-CH2), 7.70–7.85 (m, 2 H, H-6,7),
7.81 (d, 1 H, J = 8.5 Hz, H-3), 8.17 (d, 1 H, J = 8.5 Hz, H-4), 8.20–
8.35 (m, 2 H, H-5,8).
Anal. Calcd for C22H12O2S: C, 77.63; H, 3.55; S, 9.42. Found: C,
77.60; H, 3.69; S, 9.40.
2-(1-Hydroxy-1-methylethyl)anthra[1,2-b]thiophene-6,11-di-
one (2c)
Yield 83%; mp 184–184.5 °C.
1H NMR: d = 1.78 (s, 6 H, Me), 2.30 (br s, 1 H, OH), 7.28 (s, 1 H,
H-3), 7.75–7.85 (m, 2 H, H-8,9), 8.01 [d, 1 H, J = 8.2 Hz, H-4(5)],
8.20–8.35 [m, 3 H, H-5(4),7,10].
Anal. Calcd for C20H15O2Cl: C, 74.42; H, 4.68; Cl, 10.98. Found: C,
74.43; H, 4.79; Cl, 10.91.
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I. D. Ivanchikova et al.
PAPER
Anal. Calcd for C19H14O3S: C, 70.79; H, 4.38; S, 9.95. Found: C,
70.90; H, 4.54; S, 9.91.
2-Butylanthra[2,1-b]thiophene-6,11-dione (4g)
Yield: 64%; mp 83.5–84.5 °C.
1H NMR: d = 0.98 (t, 3 H, J = 7.4 Hz, Me), 1.46 (sext, 2 H, J = 7.4
Hz, g-CH2), 1.81 (quint, 2 H, J = 7.4 Hz, b-CH2), 3.02 (t, 2 H,
J = 7.4 Hz, a-CH2), 7.75–7.80 (m, 2 H, H-8,9), 8.13 [d, 1 H, J = 8.4
Hz, H-4(5)], 8.23 [d, 1 H, J = 8.4 Hz, H-5(4)], 8.25–8.30 (m, 2 H,
H-7,10), 8.50 (s, 1 H, H-1).
2-(1-Hydroxy-2-methylpropyl)anthra[1,2-b]thiophene-6,11-di-
one (2d)
Yield: 72%; mp 162–163 °C.
1H NMR: d = 0.99 (d, 3 H, J = 6.7 Hz, Me), 1.07 (d, 3 H, J = 6.7 Hz,
Me), 2.10–2.25 (m, 1 H, CHMe2), 2.30 (br s, 1 H, OH), 4.82 (d, 1
H, J = 4.7 Hz, CHO), 7.28 (s, 1 H, H-3), 7.75–7.85 (m, 2 H, H-8,9),
8.03 [d, 1 H, J = 8.2 Hz, H-4(5)], 8.25–8.35 [m, 3 H, H-5(4),7,10].
Anal. Calcd for C20H16O2S: C, 74.97; H, 5.03; S, 10.01. Found: C,
74.78; H, 5.27; S, 10.00.
Anal. Calcd for C20H16O3S: C, 71.41; H, 4.79; S, 9.53. Found: C,
71.27; H, 4.71; S, 9.38.
References
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755.
(2) Kita, Y.; Kirihara, M.; Sekihachi, J.; Okunaka, R.; Sasho,
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2-Hydroxymethylanthra[1,2-b]thiophene-6,11-dione (2e)
Yield: 87%; mp 212–213 °C.
1H NMR: d = 2.23 (br s, 1 H, OH), 5.00 (s, 2 H, CH2), 7.33 (s, 1 H,
H-3), 7.75–7.85 (m, 2 H, H-8,9), 8.05 [d, 1 H, J = 8.2 Hz, H-4(5)],
8.25–8.35 [m, 3 H, H-5(4),7,10].
Anal. Calcd for C17H10O3S: C, 69.37; H, 3.42; S, 10.89. Found: C,
69.26; H, 3.65; S, 10.81.
(5) McDonald, F. E.; Burova, S. A.; Huffman, L. G. Synthesis
2000, 970.
(6) Yue, D.; Larock, R. C. J. Org. Chem. 2002, 67, 1905.
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1995, 155.
2-(1-Cyclohexenyl)anthra[1,2-b]thiophene-6,11-dione (2f)
Yield: 76%; mp 207–208 °C.
1H NMR: d = 1.60–1.90 (m, 4 H, 4¢, 5¢-CH2), 2.10–2.60 (m, 4 H, 3¢,
6¢-CH2), 6.55–6.65 (m, 1 H, 2¢-CH), 7.19 (s, 1 H, H-3), 7.75–7.85
(m, 2 H, H-8,9), 7.98 [d, 1 H, J = 8.2 Hz, H-4(5)], 8.24 [d, 1 H,
J = 8.2 Hz, H-5(4)], 8.20–8.35 (m, 3 H, H-7,10).
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Tetrahedron Lett. 2000, 41, 5757.
(9) Shvartsberg, M. S.; Barabanov, I. I.; Fedenok, L. G.
Mendeleev Commun. 1997, 98.
Anal. Calcd for C22H16O2S: C, 76.72; H, 4.68; S, 9.31. Found: C,
76.47; H, 4.63; S, 9.35.
(10) Shvartsberg, M. S.; Ivanchikova, I. D. Tetrahedron Lett.
2000, 41, 771.
Anthra[2,1-b]thiophene-6,11-dione (4a)
(11) Barabanov, I. I.; Ivanchikova, I. D.; Shvartsberg, M. S.
Mendeleev Commun. 2000, 188.
(12) Fedenok, L. G.; Barabanov, I. I.; Ivanchikova, I. D.
Tetrahedron 2001, 57, 1331.
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3, 651.
(14) Malte, A. M.; Castro, C. E. J. Am. Chem. Soc. 1967, 89,
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Yield: 66%; mp 182.5–183.5 °C.
1H NMR: d = 7.75–7.85 (m, 2 H, H-8,9), 7.81 [d, 1 H, J = 5.5 Hz,
H-2(1)], 8.20–8.35 (m, 4 H, H-4,5,7,10), 8.81 [d, 1 H, J = 5.5 Hz,
H-1(2)].
Anal. Calcd for C16H8O2S: C, 72.71; H, 3.05; S, 12.13. Found: C,
72.54; H, 3.01; S, 11.93.
2-Phenylanthra[2,1-b]thiophene-6,11-dione (4b)
Yield: 84%; mp 246.5–247.5 °C.
1H NMR: d = 7.40–7.55 (m, 3 H, 3 HPh), 7.75–7.90 (m, 4 H, 2 HPh,
H-8,9), 8.19 [d, 1 H, J = 8.4 Hz, H-4(5)], 8.25–8.35 [m, 3 H, H-
5(4),7,10], 9.08 (s, 1 H, H-1).
Anal. Calcd for C22H12O2S: C, 77.63; H, 3.55; S, 9.42. Found: C,
77.67; H, 3.61; S, 9.50.
2-(1-Hydroxy-1-methylethyl)anthra[2,1-b]thiophene-6,11-di-
one (4c)
Yield: 97%; mp 171–172 °C.
1H NMR: d = 1.77 (s, 6 H, Me), 2.32 (br s, 1 H, OH), 7.75–7.85 (m,
2 H, H-8,9), 8.14 [d, 1 H, J = 8.4 Hz, H-4(5)], 8.24 [d, 1 H, J = 8.4
Hz, H-5(4)], 8.25–8.30 (m, 2 H, H-7,10), 8.59 (s, 1 H, H-1).
Anal. Calcd for C19H14O3S: C, 70.79; H, 4.38; S, 9.95. Found: C,
70.80; H, 4.20; S, 9.81.
Synthesis 2004, No. 13, 2131–2134 © Thieme Stuttgart · New York