Site-selective arylation of alizarin and purpurin based on Suzuki-Miyaura cross-coupling reactions

Article abstract of DOI:10.1002/ejoc.201001497

A variety of arylated anthraquinones were prepared by site-selective Suzuki-Miyaura cross-coupling reactions of the bis- and tris(triflates) of alizarin and purpurin, respectively. The site-selectivity is controlled by the electronic influence of the carb

Full text of DOI:10.1002/ejoc.201001497

FULL PAPER
DOI: 10.1002/ejoc.201001497
Site-Selective Arylation of Alizarin and Purpurin Based on Suzuki–Miyaura
Cross-Coupling Reactions
Ahmed Mahal,[a] Alexander Villinger,[a] and Peter Langer*[a,b]
Keywords: Synthetic methods / Homogeneous catalysis / Palladium / Aromatic substitution / Cross-coupling /
Regioselectivity
A variety of arylated anthraquinones were prepared by site-
selective Suzuki–Miyaura cross-coupling reactions of the bis-
and tris(triflates) of alizarin and purpurin, respectively. The
site-selectivity is controlled by the electronic influence of the
carbonyl group and by steric parameters.
Introduction
Anthraquinones are of considerable pharmacological rel-
evance and represent an important core structure of many
natural products.[1] They have been isolated both as O-gly-
cosides and aglycons. For example, daunorubicin, adriamy-
cin, saintopin, and aclarubicin, which belong to the class of
the anthracyclines, exhibit strong anticancer and antibiotic
activities. Structurally more simple anthraquinones are
found, for example, in the natural products pulmatin,
chrysophanic acid, vismiaquinone, anthragallol, questin,
mumbaistatin, and several others (Figure 1).[2,3] A broad
range of pharmacological activities, including cytotoxic, an-
timicrobial, anti-inflammatory or antimalaria activity, have
been reported for substituted anthraquinones. Besides natu-
ral products and pharmaceutical chemistry, anthraquinones
are important core structures in the field of analytical
chemistry and material sciences. In fact, they show interest-
ing redox, UV, and luminescence properties.[4]
Figure 1. Structure of anthraquinone natural products.
Interestingly, these reactions proceed with excellent site-
selectivity in favor of the sterically more hindered position
1, for electronic reasons. Herein, we report full details of
these studies and reveal, for the first time, site-selective reac-
tions of purpurin (1,2,4-trihydroxyanthraquinone).
Polyhalogenated molecules represent interesting sub-
strates in palladium(0)-catalyzed cross-coupling reactions.[5]
The site-selectivity is generally controlled by steric and elec-
tronic parameters. Recently, we have reported Suzuki and
Heck reactions of tetrabromothiophene, tetrabromo-N-
methylpyrrole, tetrabromoselenophene, and other polyhalo-
genated heterocycles.[6] We also reported site-selective
Suzuki–Miyaura reactions of the bis(triflate) of methyl 2,5-
dihydroxybenzoate and other arenes.[7] The first attack
often occurs at the sterically less hindered carbon atom. Re-
cently, we have reported Suzuki–Miyaura reactions of the
bis(triflate) of 1,2-dihydroxy-anthraquinone (alizarin).[8]
Results and Discussion
Alizarin
Alizarin (1) was transformed into the bis(triflate) 2 in
81% yield (Scheme 1). 1,2-Diarylanthraquinones 4a–f were
prepared by Suzuki reactions of 2 with 2.4 equiv. of aryl-
boronic acids (Scheme 2, Table 1). The best yields were ob-
tained when [Pd(PPh3)4] was used as the catalyst, K3PO4 as
the base, and dioxane as the solvent (Table 2). The yields
dropped when toluene or tetrahydrofuran (THF) was used.
The use of [Pd(PPh3)2Cl2] proved to be less successful in
terms of yield, and an inseparable complex mixture was
formed when [Pd(OAc)2] was used in the presence of
XPhos. The yield of 4b was relatively low as a result of
partial hydrolysis of 2 to give a monoaryl hydroxyanthra-
quinone, however, this side-reaction was observed only for
the synthesis of 4b, and was not seen for the other reactions.
[a] Institut für Chemie der Universität Rostock,
Albert-Einstein-Straße 3a, 18059 Rostock, Germany
Fax: +49-381-498-6411
E-mail: peter.langer@uni-rostock.de
[b] Leibniz Institut für Katalyse e.V. an der Universität Rostock,
Albert-Einstein-Straße 29a, 18059 Rostock
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001497.
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The moderate yield of 4f can be explained by incomplete plained by formation of bis-adducts 4 as the major side-
conversion and practical problems that occurred during the reaction together with incomplete conversion (inspection of
chromatographic purification. The use of 2-methylphen- the crude product mixture by thin-layer chromatography).
ylboronic acid resulted in the formation of a complex mix-
ture, presumably for steric reasons.
Scheme 3. Synthesis of 5a–h. Reagents and conditions: (i) 2
(1.0 equiv.), 3a–d or 3g–j (1.0 equiv.), [Pd(PPh3)4] (3 mol-%),
K3PO4 (1.5 equiv.), 1,4-dioxane (3 mL per 0.5 mmol of 2), 90 °C,
10 h.
Scheme 1. Synthesis of 2. Reagents and conditions: (i) CH2Cl2, 1
(1.0 equiv.), –78 °C, pyridine (4.0 equiv.), Tf2O (2.4 equiv.), –78 Ǟ
20 °C, 14 h.
Table 3. Synthesis of 5a–h.
3
5
Ar
% Yield of 5[a]
a
b
c
d
g
h
i
a
b
c
d
e
f
4-(F3C)C6H4
4-(MeO)C6H4
4-tBuC6H4
74
67
61
85
84
79
50
52
4-ClC6H4
3-(F3C)C6H4
3-(MeO)C6H4
4-FC6H4
Scheme 2. Synthesis of 4a–f. Reagents and conditions: (i) 2
(1.0 equiv.), 3a–f (2.4 equiv.), [Pd(PPh3)4] (6 mol-%), K3PO4
(3.0 equiv.), 1,4-dioxane (4 mL per 0.5 mmol of 2), 110 °C, 10 h.
g
h
j
4-(CF3O)C6H4
[a] Yield of isolated product.
Table 1. Synthesis of 4a–f.
The possibilities of one-pot Suzuki coupling reactions of
2 with two different arylboronic acids were next studied.
The boronic acids were added in a sequential manner. Dur-
ing the optimization, it proved to be important to carry out
the first step of the one-pot reaction at 90 °C and the sec-
ond step at 110 °C (Scheme 4). The one-pot reactions of 2
with various arylboronic acids afforded 1,2-diarylanthra-
quinones 6a–f in 50–68% yields (Table 4). The moderate
yields can be explained by formation of a small amount of
bis-adducts 4.
3, 4
Ar
% Yield of 4[a]
a
b
c
d
e
f
4-(F3C)C6H4
4-(MeO)C6H4
4-tBuC6H4
4-ClC6H4
4-MeC6H4
4-EtC6H4
77
40
76
81
77
59
[a] Yield of isolated product.
Table 2. Optimization of the synthesis of 4d.
Entry Base[a,b] Solvent[c]
Catalyst[d]
% Yield of 4d[e]
1
2
3
4
5
6
K2CO3 dioxane
K2CO3 toluene
K2CO3 THF
K3PO4 dioxane
K3PO4 toluene
K3PO4 THF
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)4]
[Pd(PPh3)4]
[Pd(PPh3)4]
74
55
61
81
48
73
Scheme 4. Synthesis of 6a–f. Reagents and conditions: (i) (1) 2
(1.0 equiv.), 3a–d or 3g (1.0 equiv.), [Pd(PPh3)4] (3 mol-%), K3PO4
(1.5 equiv.), 1,4-dioxane, 90 °C, 10 h; (2) 3a or 3c (1.1 equiv.),
K3PO4 (1.5 equiv.), 1,4-dioxane, 110 °C, 10 h.
[a] 1 mL (2 m aqueous solution per 0.5 mmol of 2). [b] K3PO4
(3.0 equiv. per 0.5 mmol of 2). [c] 4 mL per 0.5 mmol of 2. [d]
6 mol-% per 0.5 mmol of 2. [e] Yield of isolated product.
Table 4. Synthesis of 1,2-diarylanthraquinones 6a–f.
The reaction of 2 with 1.0 equiv. of arylboronic acids
gave rise to the issue of site-selectivity. The reaction of 2
with 1.0 equiv. of arylboronic acids 3a–d or 3g–j afforded
1-arylanthraquinones 5a–h. The best yields were again ob-
tained when [Pd(PPh3)4] and K3PO4 were used and when
the reaction was carried out at 90 °C instead of 110 °C (re-
action time 10 h) (Scheme 3, Table 3). The electron-poor ar-
ylboronic acids 3d and 3g gave the best yields. The use of
2-methylphenylboronic acid resulted in the formation of a
complex mixture, presumably for steric reasons. Only mod-
3
6
Ar1
Ar2
% Yield of 6[a]
a,c
b,c
c,a
d,c
g,a
g,c
a
b
c
d
e
f
4-(F3C)C6H4
4-(MeO)C6H4
4-tBuC6H4
4-ClC6H4
3-(F3C)C6H4
3-(F3C)C6H4
4-tBuC6H4
4-tBuC6H4
4-(F3C)C6H4
4-tBuC6H4
4-(F3C)C6H4
4-tBuC6H4
65
50
60
61
68
61
[a] Yield of isolated product.
The structure of product 5c was confirmed by 2D NMR
erate yields were obtained in some cases, which can be ex- experiments (HMBC, NOESY) (see the Supporting Infor-
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Site-Selective Arylation of Alizarin and Purpurin
mation). The structures of 4c, 5b, and 6a were indepen- follows. The first attack of palladium(0)-catalyzed cross-
dently confirmed by X-ray crystal structure analyses (see coupling reactions generally occurs at the electronically
Figures 2, 3, and 4).[9]
more deficient and sterically less hindered position.[5,10] Po-
sition 1 of bis(triflate) 2 is sterically more hindered than
position 2 (Figure 5), however, position 1 (located in β-posi-
tion to the carbonyl group) is more electron-deficient than
position 2. Hand and Zhang reported a simple guide for
the prediction of the site selectivity of palladium(0)-cata-
lyzed cross-coupling reactions based on the 1H NMR chem-
ical shift values of the compound in which the triflate or
halogen groups are replaced by hydrogen atoms.[10] In fact,
the 1H NMR signals of the aromatic proton located at posi-
tion 1 of anthraquinone is shifted to lower field compared
to the proton located at position 2. In addition, a neigh-
boring group effect by the quinone carbonyl group (chela-
tion of the approaching palladium complex) might play a
role. In conclusion, the first attack occurs at the sterically
more hindered position for electronic reasons.
Figure 2. X-ray crystal structure of 4c.
Figure 5. Possible explanation for the site-selective reaction of 2.
The reaction of commercially available purpurin (7) with
triflic anhydride, in the presence of pyridine, afforded tris-
(triflate) 8 in 43% yield (Scheme 5).
Figure 3. X-ray crystal structure of 5b.
Scheme 5. Synthesis of 8. Reagents and conditions: (i) CH2Cl2, 7
(1.0 equiv.), –78 °C, pyridine (7.0 equiv.), Tf2O (5.0 equiv.), –78 Ǟ
20 °C, 14 h.
The Suzuki–Miyaura reaction of 8 with 4.0 equiv. of bor-
onic acid derivatives afforded 1,2,4-triarylanthraquinones
9a–f (Scheme 6, Table 5). In these reactions [Pd(PPh3)4] was
used as the catalyst and K3PO4 as the base (Table 6). The
best yields were obtained when the reaction was carried out
at 120 °C. The electron-rich arylboronic acids 3b, 3c, and
3k gave very good yields. In contrast, electron-poor aryl-
boronic acids 3a, 3d, and 3i provided only moderate to
good yields. This result, which is in contrast to the corre-
sponding reactions of alizarin-derived bis(triflate) 2, might
be explained by the fact that tris(triflate) 8 is more electron-
poor than bis(triflate) 2. The moderate yields of products
9a and 9e can be explained by incomplete conversion and
Figure 4. X-ray crystal structure of 6a.
The first attack of the arylboronic acid occurred at car- practical problems that occurred during the chromato-
bon atom C-1 of bis(triflate) 2, which can be explained as graphic purification.
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P. Langer et al.
FULL PAPER
be important to carry out the reaction at 95 °C instead of
105 °C. The moderate yields can be explained by formation
of bis- and tris-adducts 10 and 9 as the major side reactions
and by incomplete conversion (reaction monitored by
TLC).
Scheme 6. Synthesis of 9a–f. Reagents and conditions: (i) 8
(1.0 equiv.), 3a–d, 3i, or 3k (4.0 equiv.), [Pd(PPh3)4] (10 mol-%),
K3PO4 (5.0 equiv.), 1,4-dioxane (5 mL per 0.15 mmol of 8), 120 °C,
12 h.
Table 5. Synthesis of 9a–f.
3
9
Ar
% Yield of 9[a]
Scheme 8. Synthesis of 11a–f. Reagents and conditions: (i) 8
(1.0 equiv.),
3
(1.0 equiv.), [Pd(PPh3)4] (3.0 mol-%), K3PO4
a
b
c
d
i
a
b
c
d
e
f
4-(F3C)C6H4
4-(MeO)C6H4
4-tBuC6H4
4-ClC6H4
4-FC6H4
43
73
83
60
57
86
(1.5 equiv.), 1,4-dioxane (3 mL per 0.15 mmol of 8), 95 °C, 10 h.
k
C6H4
Table 8. Synthesis of 11a–f.
% Yield of 11[a]
[a] Yield of isolated product.
3
11
Ar
b
c
a
b
c
d
e
f
4-(MeO)C6H4
4-tBuC6H4
4-MeC6H4
4-EtC6H4
3-(CF3)C6H4
3-ClC6H4
38
41
61
65
40
56
Table 6. Optimization of the synthesis of 9c.
e
Entry Base[a,b] Solvent[c]
Catalyst[d]
% Yield of 9c[e]
f
g
m
1
2
3
4
5
6
K2CO3
K2CO3
K2CO3
K3PO4
K3PO4
K3PO4
dioxane
toluene
THF
dioxane
toluene
THF
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)4]
[Pd(PPh3)4]
[Pd(PPh3)4]
70
39
62
83
66
74
[a] Yield of isolated product.
The one-pot reaction of 8 with different arylboronic ac-
ids afforded product 12 in 45% yield (Scheme 9). The first
step of the reaction was carried out using 2.0 equiv. of aryl-
boronic acid 3c at 95 °C (10 h). The second step was carried
out using 3d at 110 °C (10 h).
[a] 1 mL (2 m aqueous solution) per 0.15 mmol of 8. [b] K3PO4
(5.0 equiv. per 0.15 mmol of 8). [c] 5 mL per 0.15 mmol of 8. [d]
10 mol-% per 0.15 mmol of 8. [e] Yield of isolated product.
The reaction of the 8 and 2.0 equiv. of arylboronic acid
afforded 1,4-diaryl-2-[(trifluoromethyl)sulfonyloxy]anthra-
quinones 10a–e (Scheme 7, Table 7). During the optimiza-
tion, it proved to be important to carry out the reaction at
105 °C instead of 120 °C.
Scheme 9. Synthesis of 12. Reagents and conditions: (i) (1) 8
(1.0 equiv.), 3c (2.0 equiv.), [Pd(PPh3)4] (6 mol-%), K3PO4
(3.0 equiv.), 1,4-dioxane, 95 °C, 10 h; (2) 3d (1.0 equiv.), [Pd-
(PPh3)4] (3 mol-%), K3PO4 (1.5 equiv.), 1,4-dioxane, 110 °C, 10 h.
Scheme 7. Synthesis of 10a–e. Reagents and conditions: (i) 2
(1.0 equiv.),
3
(2.0 equiv.), [Pd(PPh3)4] (6 mol-%), K3PO4
The structures of products 10e and 11f were confirmed
by 2D NMR experiments (NOESY and HMBC) (see the
Supporting Information). The structures of 10a and 11e
were independently confirmed by X-ray crystal structure
analyses (see Figures 6 and 7).[9]
(3.0 equiv.), 1,4-dioxane (4 mL per 0.15 mmol of 8), 105 °C, 10 h.
Table 7. Synthesis of 10a–e.
3
10
Ar
% Yield of 10[a]
a
c
e
f
a
b
c
d
e
4-(CF3)C6H4
4-tBuC6H4
4-MeC6H4
4-EtC6H4
61
81
51
74
60
The site-selectivity can be explained as follows. Positions
2 and 4 of 8 are sterically less hindered than position 1
(Figure 8), however, because positions 1 and 4 of 8 are more
electron-deficient than position 2, the first attack occurs at
the sterically less hindered and more electronically deficient
position 4. The second attack occurs at position 1, which is
l
3,5-MeC6H4
[a] Yield of isolated product.
The site-selective Suzuki–Miyaura reactions of 8 with sterically hindered, but electron deficient. The third attack
1.0 equiv. of arylboronic acid afforded products 11a–f occurs at position 2, which is not electron-deficient and not
(Scheme 8, Table 8). During the optimization, it proved to sterically hindered.
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Site-Selective Arylation of Alizarin and Purpurin
Experimental Section
General Comments: All solvents were dried by standard methods
and all reactions were carried out under an inert atmosphere. The
deuterated solvents indicated were used for 1H and 13C NMR mea-
surements. Mass spectrometric data (MS) were obtained by elec-
tron ionization (EI, 70 eV), chemical ionization (CI, isobutane), or
electrospray ionization (ESI). Silica gel 60 (0.063–0.200 mm, 70–
230 mesh) was used for preparative-scale chromatography.
1,2-Bis[(trifluoromethyl)sulfonyloxy]anthraquinone (2). General Pro-
cedure: To a solution of 1 (1.0 equiv.) in CH2Cl2 (10 mL/mmol) was
added pyridine (4.0 equiv.) at room temperature under an argon
atmosphere. After 10 min, Tf2O (2.4 equiv.) was added at –78 °C
and the mixture was warmed to room temperature and stirred over-
night. The reaction mixture was filtered and the filtrate was concen-
trated in vacuo. The products of the reaction mixture were isolated
by rapid column chromatography (flash silica gel, heptanes/
EtOAc).
Figure 6. X-ray crystal structure of 10a.
Starting with 1 (1.9 g, 8.0 mmol), pyridine (2.6 mL, 32.0 mmol),
CH2Cl2 (80 mL), and Tf2O (3.2 mL, 19.2 mmol), 2 was isolated as
a yellow solid (3.25 g, 81%); m.p. 152–154 °C. 1H NMR (300 MHz,
CDCl3): δ = 7.80–7.85 (m, 3 H, ArH), 8.23–8.26 (m, 1 H, ArH),
8.29–8.32 (m, 1 H, ArH), 8.46 (d, J = 8.76 Hz, 1 H, ArH) ppm.
13C NMR (75.4 MHz, CDCl3): δ = 118.5 (q, JF,C = 320.9 Hz, CF3),
118.6 (d, JF,C = 320.7 Hz, CF3), 127.4 (CH), 127.8 (C), 128.0,
128.1, 128.9 (CH), 132.0, 133.7, 134.1 (C), 135.1, 135.2 (CH),
139.2, 145.0 (C), 180.2, 180.5 (CO) ppm. 19F NMR (282 MHz,
CDCl3): δ = –73.4 (q, JF = 3.02, 6.02 Hz, 3 F, CF3), –72.58 (q, JF
= 2.84, 5.83 Hz, 3 F, CF ) ppm. IR (KBr): ν = 1674 (s), 1601, 1587,
˜
3
1472 (w), 1427 (s), 1330, 1316, 1282, 1249 (w), 1208 (s), 1164, 1150
(m), 1124 (s), 1007, 998, 901, 856 (m), 807 (s), 795, 738 (m), 721,
708 (s), 684, 676, 655, 643 (w), 618, 606 (m), 589, 575, 569 (s), 543,
529 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 504 (36) [M + H]+,
435 (05), 375 (08), 348 (23), 279 (100), 251 (76), 223 (26), 154 (26),
126 (60). HRMS (EI, 70 eV): calcd. for C16H6O8F6S2 [M]+
503.94028; found 503.940108.
General Procedure for Suzuki–Miyaura Reactions: A 1,4-dioxane
solution (4 mL per 3 mmol of 2) of 2, K3PO4, [Pd(PPh3)4], and
arylboronic acid 3 was stirred at 110 °C or 90 °C for 10 h. After
cooling to 20 °C, distilled water was added, the organic and the
aqueous layers were separated, and the latter was extracted with
CH2Cl2. The combined organic layers were dried (Na2SO4), fil-
tered, and the filtrate was concentrated in vacuo. The residue was
purified by column chromatography.
Figure 7. X-ray crystal structure of 11e.
1,2-Bis[4-(trifluoromethyl)phenyl]anthraquinone (4a): Starting with
2 (250 mg, 0.5 mmol), 3a (225 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg,
6 mol-%, 0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane
(4 mL), 4a was isolated as a yellow solid (190 mg, 77%); m.p. 208–
210 °C. 1H NMR (300 MHz, CDCl3): δ = 7.01–7.07 (m, 4 H, ArH),
7.35 (d, J = 8.12 Hz, 2 H, ArH), 7.42 (d, J = 8.12 Hz, 2 H, ArH),
7.62–7.71 (m, 3 H, ArH), 7.95–8.0 (m, 1 H, ArH), 8.18–8.21 (m, 1
H, ArH), 8.45 (d, J = 8.12 Hz, 1 H, ArH) ppm. 13C NMR
(62.9 MHz, CDCl3): δ = 123.8 (q, JF,C = 272.2 Hz, CF3), 124.1 (q,
JF,C = 272.1 Hz, CF3), 124.7 (C), 124.7, 124.8, 126.7, 127.4, 127.7
(CH), 128.8 (C), 129.5, 129.7 (CH), 131.5, 132.6 (C), 134.0 (CH),
134.3 (C), 134.4 (CH), 134.5 (C), 135.1 (CH), 140.6, 143.0, 143.2,
147.3 (C), 182.7, 183.3 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ
Figure 8. Possible explanation for the site selectivity of 8.
Conclusions
= –62.69 (s, 3 F, CF ), –62.37 (s, 3 F, CF ) ppm. IR (KBr): ν =
˜
3
3
A variety of arylated anthraquinones have been synthe-
sized by site-selective Suzuki–Miyaura cross coupling reac-
tions. For the triflates of alizarin and purpurin, the site-
selectivity is controlled by electronic parameters.
1670 (m), 1633, 1615, 1580, 1416, 1397 (w), 1324, 1299 (s), 1281,
1261, 1212, 1199 (m), 1158, 1108, 1078, 1061, 1016 (s), 977 (w),
958, 947 (m), 900, 866 (w), 835, 825 (s), 797 (m), 787, 768, 757,
747, 740 (w), 720, 711 (s), 679 (w), 672 (m), 648 (w), 636 (m), 606
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2079

P. Langer et al.
(s), 545 (w) cm–1. GC-MS (EI, 70 eV): m/z (%) = 496 (78) [M+], 430 (37Cl, 67) [M+], 429 (35Cl, 91) [M + H+], 428 (35Cl, 93) [M+],
FULL PAPER
495 (100), 477 (09), 428 (25), 427 (86). HRMS (EI, 70 eV): calcd.
427 (100), 395 (30), 394 (24), 393 (91), 357 (17), 300 (26). HRMS
(EI, 70 eV): calcd. for C26H13Cl2O2 ([M – H]+, 35Cl) 427.02871;
found 427.028111.
for C28H13O2F6 [M – H]+ 495.08143; found 495.081086.
1,2-Bis(4-methoxyphenyl)anthraquinone (4b): Starting with
2
(250 mg, 0.5 mmol), 3b (180 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg, 1,2-Bis(4-methylphenyl)anthraquinone (4e): Starting with 2 (250 mg,
6 mol-%, 0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane
0.5 mmol), 3e (162 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg, 6 mol-%,
(4 mL), 4b was isolated as red crystals (84 mg, 40%); m.p. 220–
0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane (4 mL),
221 °C. 1H NMR (300 MHz, CDCl3): δ = 3.66 (s, 3 H, OCH3), 4e was isolated as a yellow solid (149 mg, 77%); m.p. 218–220 °C.
3.71 (s, 3 H, OCH3), 6.61 (d, J = 8.76 Hz, 2 H, ArH), 6.71 (d, J =
8.73 Hz, 2 H, ArH), 6.83 (d, J = 7.92 Hz, 4 H, ArH), 7.60–7.65
1H NMR (300 MHz, CDCl3): δ = 2.20 (s, 3 H, CH3), 2.27 (s, 3 H,
CH3), 6.82–7.00 (m, 4 H, ArH), 6.90 (d, J = 7.86 Hz, 2 H, ArH),
(m, 3 H, ArH), 7.97–8.0 (m, 1 H, ArH), 8.15–8.18 (m, 1 H, ArH), 6.98 (d, J = 7.88 Hz, 2 H, ArH), 7.60–7.70 (m, 3 H, ArH), 8.00–
8.30 (d, J = 8.07 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, 8.03 (m, 1 H, ArH), 8.18–8.21 (m, 1 H, ArH), 8.34 (d, J = 8.01 Hz,
CDCl3): δ = 54.0 (OCH3), 54.1 (OCH3), 112.1, 112.2, 125.4, 126.0, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 21.1 (CH3),
126.3, 129.4, 129.6 (CH), 130.8, 131.0, 131.4, 131.7 (C), 132.4
(CH), 132.5 (C), 133.0 (CH), 134.0 (C), 134.2 (CH), 140.0, 148.0, 131.8, 132.8 (C), 133.5 (CH), 133.6 (C), 134.1 (CH), 135.1 (C),
157.1, 157.5 (C), 182.3, 183.0 (CO) ppm. IR (KBr): ν = 2838 (w), 135.3 (CH), 136.0, 136.7, 136.8, 137.2, 142.4, 149.2 (C), 183.4,
21.4 (CH3), 126.5, 127.0, 127.4, 128.4, 128.5, 129.1, 129.3 (CH),
˜
1671 (s), 1606 (m), 1588, 1550, 1516, 1464, 1451, 1440, 1412, 1394 183.9 (CO) ppm. IR (KBr): ν = 2920, 2851 (w), 1672, 1662 (s),
˜
(w), 1328, 1311 (m), 1297, 1240 (s), 1208, 1107, 1088, 1074 (m), 1590, 1574, 1548, 1512, 1478, 1445, 1414, 1385 (w), 1327, 1313 (m),
1027 (s), 977 (w), 954 (s), 858 (w), 840 (m), 828 (s), 811 (w), 800 1293, 1278, 1260 (s), 1241, 1208 (m), 1182, 1159, 1112, 1070, 1039
(s), 767, 749 (w), 727 (m), 718 (s), 697 (m), 669, 649 (w), 640, 601,
588 (m), 537 (s) cm–1. GC-MS (EI, 70 eV): m/z (%) = 420 (100)
[M+], 419 (49), 405 (11), 390 (12), 389 (45), 345 (14), 312 (09).
HRMS (EI, 70 eV): calcd. for C28H20O4 [M]+ 420.13561; found
420.134505.
(w), 1018 (m), 965 (w), 952, 939 (m), 896, 854, 832 (w), 811 (s), 794
(m), 762, 749 (w), 723, 713, 701 (s), 669, 650 (w), 642 (m), 595 (w),
580, 549, 540 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 388 (49)
[M+], 374 (26). 373 (100), 371 (6). HRMS (EI, 70 eV): calcd. for
C28H20O2 [M]+ 388.14578; found 388.144687.
1,2-Bis(4-tert-butylphenyl)anthraquinone (4c): Starting with
2
1,2-Bis(4-ethylphenyl)anthraquinone (4f): Starting with 2 (250 mg,
(250 mg, 0.5 mmol), 3c (213 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg, 0.5 mmol), 3f (180 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg, 6 mol-%,
6 mol-%, 0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane 0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane (4 mL),
(4 mL), 4c was isolated as orange crystals (180 mg, 76%); m.p. 234– 4f was isolated as a brown solid (124 mg, 60%); m.p. 146–148 °C.
1
236 °C. H NMR (300 MHz, CDCl3): δ = 1.15 (s, 9 H, 3ϫCH3), 1H NMR (300 MHz, CDCl3): δ = 1.03–1.14 (m, 6 H, 2ϫCH3),
1.20 (s, 9 H, 3ϫCH3), 6.75–6.83 (m, 4 H, ArH), 7.01–7.14 (m, 4 2.43–2.55 (m, 4 H, 2ϫCH2), 6.76–6.87 (m, 6 H, ArH), 6.95 (d, J
H, ArH), 7.60–7.65 (m, 2 H, ArH), 7.71 (d, J = 8.01 Hz, 1 H,
ArH), 8.01–8.03 (m, 1 H, ArH), 8.17–8.23 (m, 1 H, ArH), 8.34 (d,
J = 8.05 Hz, 1 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ =
31.2 (3ϫCH3), 31.4 (3ϫCH3), 34.4, 34.4 (C), 124.2, 124.3, 126.6,
127.0, 127.5, 129.0, 129.0 (CH), 131.3, 132.9 (C), 133.5 (CH), 133.6
(C), 134.1, 134.9 (CH), 135.0, 136.9, 137.2, 142.7, 149.1, 149.8,
= 8.07 Hz, 2 H, ArH), 7.54–7.64 (m, 3 H, ArH), 7.94–8.01 (m, 1
H, ArH), 8.11–8.14 (m, 1 H, ArH), 8.27 (d, J = 8.04 Hz, 1 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3):
δ = 14.2, 14.4
(2ϫCH3), 27.3, 27.5 (2ϫCH2), 125.4, 125.8, 126.0 (d, J =
11.9 Hz), 126.3, 126.8, 128.1, 128.3 (CH), 130.5, 131.6 (C), 132.3
(CH), 132.5 (C), 133.0 (CH), 134.1 (C), 134.1 (CH), 136.0, 136.3,
149.8 (C), 183.4, 183.7 (CO) ppm. IR (KBr): ν = 2959 (m), 2901,
141.2, 141.3, 142.0, 148.2 (C), 182.2, 182.6 (CO) ppm. IR (KBr): ν
˜
˜
2866 (w), 1675 (s), 1663, 1588 (m), 1575, 1566, 1548, 1513, 1475, = 2962, 2849 (w), 1665 (s), 1630 (w), 1589 (m), 1572, 1512, 1478,
1456, 1410, 1394, 1360 (w), 1330, 1315 (m), 1298 (s), 1280, 1262, 1470, 1454, 1434, 1409, 1392, 1358 (w), 1325, 1313 (m), 1294, 1288,
1253, 1211, 1199 (m), 1185, 1160 (w), 1113 (m), 1072 (w), 1016 (m), 1262 (s), 1210, 1189, 1163, 1156 (m), 1114, 1089 (w), 1073 (m),
979 (w), 956 (m), 942, 904 (w), 860, 836 (m), 822 (s), 795 (m), 774,
768, 755, 745 (w), 719 (s), 690 (m), 682 (w), 662, 645 (m), 587 (s),
568, 559, 543 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 472 (45)
[M+], 457 (93), 439 (04), 415 (100), 401 (23), 383 (11). HRMS (EI,
70 eV): calcd. for C34H32O2 [M]+ 472.23968; found 472.238675.
1051, 1041, 1017, 974 (w), 951, 943 (m), 889 (w), 871 (m), 832 (s),
791 (m), 761, 738 (w), 712 (s), 694, 669, 648, 583, 553, 533 (m) cm–1.
GC-MS (EI, 70 eV): m/z (%) = 416 (30) [M+], 388 (30), 387 (100),
372 (5), 357 (4). HRMS (EI, 70 eV): calcd. for C30H24O2 [M]+
416.17708; found 416.176631.
1,2-Bis(4-chlorophenyl)anthraquinone (4d): Starting with 2 (250 mg,
0.5 mmol), 3d (185 mg, 1.2 mmol), [Pd(PPh3)4] (34 mg, 6 mol-%,
0.03 mmol), K3PO4 (320 mg, 1.5 mmol), and 1,4-dioxane (4 mL),
4d was isolated as a yellow solid (174 mg, 81%); m.p. 208–210 °C.
1-[4-(Trifluoromethyl)phenyl]-2-[(trifluoromethyl)sulfonyloxy]-
anthraquinone (5a): Starting with 2 (250 mg, 0.5 mmol), 3a (95 mg,
0.5 mmol), [Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4
(160 mg, 0.75 mmol), and 1,4-dioxane (3 mL), 5a was isolated as a
1H NMR (300 MHz, CDCl3): δ = 6.82–6.87 (m, 4 H, ArH), 7.06– yellow solid (186 mg, 74%); m.p. 135–136 °C. 1H NMR (300 MHz,
7.16 (m, 4 H, ArH), 7.61–7.70 (m, 3 H, ArH), 7.95–8.02 (m, 1 H,
ArH), 8.15–8.18 (m, 1 H, ArH), 8.34 (d, J = 8.01 Hz, 1 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 126.7, 127.4, 127.5,
CDCl3): δ = 7.29 (d, J = 8.24 Hz, 2 H, ArH), 7.64–7.71 (m, 5 H,
ArH), 7.94–7.96 (m, 1 H, ArH), 8.14–8.17 (m, 1 H, ArH), 8.43 (d,
J = 8.57 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ =
128.1, 128.2, 130.5, 130.7 (CH), 131.6, 132.6, 132.8, 133.6 (C), 117.0 (q, JF,C = 321.0 Hz, CF3), 123.1 (q, JF,C = 271.3 Hz, CF3),
133.8 (CH), 134.0 (C), 134.3 (CH), 134.6 (C), 135.1 (CH), 137.9, 124.3 (q, J = 272.0 Hz), 125.4, 126.0, 126.5, 128.1, 129.1 (CH),
138.1, 140.8, 147.7 (C), 183.0, 183.5 (CO) ppm. IR (KBr): ν = 1673
129.2, 129.6, 131.1, 132.2, 133.0 (d, J = 1.7 Hz, 1 C), 133.4, 133.7
(CH), 134.7, 136.7 (d, J = 1.1 Hz), 151.1 (C), 180.4, 180.8
˜
(s), 1589 (m), 1576, 1551 (w), 1489 (m), 1478, 1451, 1410, 1388 (w),
1326 (m), 1308, 1297, 1267 (s), 1245, 1210 (m), 1181 (w), 1159 (m), (CO) ppm. 19F NMR (282 MHz, CDCl3): δ = –74.03 (s, 3 F, CF3),
1091 (s), 1070 (m), 1014 (s), 972 (w), 954 (s), 938, 856, 846 (m),
834, 820 (s), 791, 774, 763, 729 (m), 714 (s), 698, 688 (m), 656 (w),
–62.57 (s, 3 F, CF ) ppm. IR (KBr): ν = 1674 (s), 1617, 1589, 1572,
˜
3
1479, 1452, 1433, 1418 (w), 1402 (m), 1326 (s), 1301, 1273 (m),
644 (m), 636, 573 (w), 559, 548 (m), 537 (w) cm–1. GC-MS (EI, 1249 (w), 1219, 1165, 1125, 1107, 1085, 1061 (s), 1018 (m), 1000
70 eV): m/z (%) = 432 (2ϫ37Cl, 12) [M+], 431 (37Cl, 26) [M + H+], (w), 946 (m), 793, 770, 743 (w), 723, 711 (s), 676, 651 (w), 601 (s),
2080
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2075–2087

Site-Selective Arylation of Alizarin and Purpurin
572, 528 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 500 (48) [M+],
499 (13), 431 (25), 368 (24), 367 (100), 366 (24), 298 (23). HRMS
(EI, 70 eV): calcd. for C22H10O5F6S [M]+ 500.01476; found
500.013920.
465 (35Cl, 09) [M+], 431 (09), 335 (32), 334 (25), 333 (100), 332
(14), 298 (35), 297 (15), 270 (19). HRMS (EI, 70 eV): calcd. for
C21H10ClF3O5S ([M]+, 35Cl) 465.98841; found 465.987508.
1-(3-Trifluoromethylphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthra-
1-(4-Methoxyphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthraquinone
quinone (5e): Starting with 2 (250 mg, 0.5 mmol), 3g (95 mg,
(5b): Starting with 2 (250 mg, 0.5 mmol), 3b (76 mg, 0.5 mmol), 0.5 mmol), [Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (160 mg, (160 mg, 0.75 mmol), and 1,4-dioxane (3 mL), 5e was isolated as a
0.75 mmol), and 1,4-dioxane (3 mL), 5b was isolated as orange yellow solid (209 mg, 84%); m.p. 115–117 °C. 1H NMR (300 MHz,
crystals (154 mg, 67 %); m.p. 140–142 °C. 1H NMR (300 MHz, CDCl3): δ = 7.35 (d, J = 7.62 Hz, 1 H, ArH), 7.42 (s, 1 H, ArH),
CDCl3): δ = 3.82 (s, 3 H, OCH3), 6.94 (d, J = 8.76 Hz, 2 H, ArH),
7.07 (d, J = 8.76 Hz, 2 H, ArH), 7.60–7.67 (m, 3 H, ArH), 7.96–
7.52 (t, J = 7.76 Hz, 1 H, ArH), 7.60–7.73 (m, 4 H, ArH), 7.89–
7.92 (m, 1 H, ArH), 8.08–8.10 (m, 1 H, ArH), 8.38 (d, J = 8.64 Hz,
8.00 (m, 1 H, ArH), 8.11–8.14 (m, 1 H, ArH), 8.36 (d, J = 8.67 Hz, 1 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 117.0 (q, JF,C
1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 55.2 (OCH3), = 320.6 Hz, CF3), 123.0 (q, JF,C = 272.2 Hz, CF3), 124.1 (q, J =
113.8 (CH), 118.2 (q, JF,C = 320.4 Hz, CF3), 125.4 (C), 126.2,
3.8 Hz), 124.6 (q, J = 3.8 Hz), 125.4, 126.0, 126.5, 127.8 (d, J =
126.8, 127.5, 129.2, 130.0 (CH), 132.3, 133.5 (C), 134.0 (CH), 4.0 Hz), 129.1 (CH), 129.5, 130.0 (C), 131.2 (CH), 132.2, 133.0 (d,
134.1, 134.5 (C), 134.6 (CH), 137.3, 152.0, 159.6 (C), 182.0, 182.1 J = 5.5 Hz, 1 C), 133.3 (CH), 133.6 (C), 133.7 (d, J = 4.4 Hz,
(CO) ppm. 19F NMR (282 MHz, CDCl3): δ = –74.04 (s, 3 F, CH), 134.4, 144.0, 150.2 (C), 180.4, 180.7 (CO) ppm. 19F NMR
CF ) ppm. IR (KBr): ν = 2838 (w), 1671 (s), 1606 (m), 1588, 1550,
(282 MHz, CDCl3): δ = –74.10 (s, 3 F, CF3), –62.70 (s, 3 F,
˜
3
1516, 1464, 1451, 1440, 1412, 1394 (w), 1328, 1311 (m), 1297, 1240
(s), 1208, 1107, 1088, 1074 (m), 1027 (s), 977 (w), 954 (s), 858 (w),
840 (m), 828 (s), 811 (w), 800 (s), 767, 749 (w), 727, 718 (s), 697
CF ) ppm. IR (KBr): ν = 1673 (s), 1589, 1568, 1492, 1479 (w),
˜
3
1418, 1308 (m), 1277, 1274 (w), 1250 (m), 1213, 1167, 1121, 1099,
1069 (s), 1001 (w), 955 (m), 883, 839, 804 (s), 770 (w), 727, 712,
(m), 669, 649 (w), 640, 601, 588 (m), 537 (s) cm–1. GC-MS (EI, 702 (s), 689, 652 (w), 628, 598 (s), 572 (m) cm–1. GC-MS (EI,
70 eV): m/z (%) = 462 (55) [M+], 330 (23), 329 (100), 314 (17), 286
(11), 202 (14). HRMS (EI, 70 eV): calcd. for C22H13O6F3S [M]+
462.03794; found 462.037734.
70 eV): m/z (%) = 500 (34) [M+], 431 (12), 368 (21), 367 (100), 266
(16), 347 (24). HRMS (EI, 70 eV): calcd. for C22H10O5F6S [M]+
500.01476; found 500.015351.
1-(4-tert-Butylphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthraquinone
1-(3-Methoxyphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthraquinone
(5c): Starting with 2 (250 mg, 0.5 mmol), 3c (90 mg, 0.5 mmol), (5f): Starting with 2 (250 mg, 0.5 mmol), 3h (76 mg, 0.5 mmol),
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (160 mg, [Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (160 mg,
0.75 mmol), and 1,4-dioxane (3 mL), 5c was isolated as yellow crys-
0.75 mmol), and 1,4-dioxane (3 mL), 4f was isolated as a yellow
tals (149 mg, 61%); m.p. 160–162 °C. 1H NMR (250 MHz, CDCl3): solid (183 mg, 79 %); m.p. 115–116 °C. 1H NMR (300 MHz,
δ = 1.31 (s, 9 H, 3ϫCH3), 7.07 (d, J = 8.4 Hz, 2 H, ArH), 7.42 (d,
J = 8.51 Hz, 2 H, ArH), 7.58–7.67 (m, 3 H, ArH), 7.96–8.0 (m, 1
H, ArH), 8.11–8.14 (m, 1 H, ArH), 8.36 (d, J = 8.81 Hz, 1 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 31.3 (3ϫCH3), 34.7
CDCl3): δ = 3.72 (s, 3 H, OCH3), 6.69–6.73 (m, 2 H, ArH), 6.91–
6.95 (m, 1 H, ArH), 7.31 (t, J = 8.76 Hz, 1 H, ArH), 7.58–7.66 (m,
3 H, ArH), 7.94–8.01 (m, 1 H, ArH), 8.10–8.13 (m, 1 H, ArH), 8.36
(d, J = 8.70 Hz, 1 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ
(C), 118.2 (q, JF,C = 318.5 Hz, CF3), 125.2, 126.3, 126.9, 127.7, = 55.2 (OCH3), 113.8, 114.3 (CH), 118.2 (q, JF,C = 320.5 Hz, CF3),
128.3, 129.3 (CH), 130.5, 132.4, 133.4 (C), 134.1 (CH), 134.1 (C), 120.8, 126.1, 126.8, 127.5, 129.4, 129.5 (CH), 132.2, 133.3, 134.0
134.5 (CH), 134.6, 137.6, 151.2, 151.8 (C), 181.9, 182.0 (CO) ppm.
19F NMR (282 MHz, CDCl3): δ = –74.2 (s, 3 F, CF3) ppm. IR (C), 181.7, 181.8 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ =
(KBr): ν = 2960, 2930, 2869, 1675, 1665, 1590, 1580, 1573, 1429 –74.02 (s, 3 F, CF ) ppm. IR (KBr): ν = 1679 (m), 1606, 1571, 1488,
(C), 134.1 (CH), 134.3 (C), 134.6 (CH), 135.0, 137.1, 151.5, 159.5
˜
˜
3
(w), 1410 (m), 1362, 1329, 1316, 1297 (w), 1267 (m), 1205 (s), 1165 1455 (w), 1422 (s), 1327, 1300 (w), 1270 (m), 1250 (w), 1210, 1166,
(m), 1129 (s), 1079, 1040, 1017, 997 (w), 946, 879, 843 (m), 820 (s),
792, 775, 767, 757, 745 (w), 725 (m), 713 (s), 683, 671 (w), 642 (m),
603 (s), 573 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 488 (18) [M+],
473 (100), 431 (31), 325 (58), 299 (26), 239 (08). HRMS (EI, 70 eV):
calcd. for C25H19O5F3S [M]+ 488.08998; found 488.090070.
1152, 1132 (s), 1096, 1076 (w), 1038 (m), 1000 (w), 959 (m), 892,
848 (s), 825, 810, 780, 769 (m), 742 (w), 725 (m), 707, 701 (s), 671
(m), 627, 597 (s), 571 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 462
(40) [M+], 330 (21), 329 (100), 314 (28), 298 (10), 286 (14), 202 (13).
HRMS (EI, 70 eV): calcd. for C22H13O6F3S [M]+ 462.03794; found
462.038112.
1-(4-Chlorophenyl)-2-[(trifluoromethyl)sulfonyloxy]anthraquinone
(5d): Starting with 2 (250 mg, 0.5 mmol), 3d (78 mg, 0.5 mmol), 1-(4-Fluorophenyl)-2-[(trifluoromethyl)sulfonyloxy]anthraquinone
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (160 mg, (5g): Starting with 2 (250 mg, 0.5 mmol), 3i (70 mg, 0.5 mmol),
0.75 mmol), and 1,4-dioxane (3 mL), 5d was isolated by as a yellow
solid (199 mg, 85 %); m.p. 160–162 °C. 1H NMR (300 MHz,
CDCl3): δ = 7.08–7.11 (m, 2 H, ArH), 7.38–7.40 (m, 2 H, ArH),
7.62–7.71 (m, 3 H, ArH), 7.96–8.00 (m, 1 H, ArH), 8.14–8.17 (m,
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (160 mg,
0.75 mmol), and 1,4-dioxane (3 mL), 5g was isolated as a yellow
solid (113 mg, 50 %); m.p. 136–138 °C. 1H NMR (300 MHz,
CDCl3): δ = 7.11–7.14 (m, 4 H, ArH), 7.63–7.72 (m, 3 H, ArH),
1 H, ArH), 8.41 (d, J = 8.68 Hz, 1 H, ArH) ppm. 13C NMR 7.97–8.00 (m, 1 H, ArH), 8.16–8.20 (m, 1 H, ArH), 8.42 (d, J =
(75.4 MHz, CDCl3): δ = 118.1 (q, JF,C = 320.5 Hz, CF3), 126.3, 8.70 Hz, 1 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 115.4,
127.0, 127.6, 128.7, 129.9, 130.0 (CH), 132.1, 132.3, 133.3, 134.1,
134.2 (C), 134.3 (CH), 134.5 (C), 134.7 (CH), 136.1, 151.4 (C),
115.7 (CH), 118.1 (q, JF,C = 318.3 Hz, CF3), 126.3, 127.0, 127.5
(CH), 129.4 (d, JF,C = 3.7 Hz, 1 C), 129.7, 130.4, 130.5 (CH), 132.2,
181.6, 182.0 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ = –73.92 133.4, 134.1 (C), 134.2 (CH), 134.3 (C), 134.6 (CH), 136.3, 151.5
(s, 3 F, CF ) ppm. IR (KBr): ν = 1676 (s), 1589, 1579, 1570, 1492, (C), 162.7 (d, JF,C = 247.7 Hz, CF), 181.7, 182.0 (CO) ppm. 19F
˜
3
1477, 1453 (w), 1408 (m), 1327, 1314, 1300 (w), 1270 (m), 1253 (w),
NMR (282 MHz, CDCl3): δ = –113.01 (s, 1 F, CF), –74.00 (s, 3 F,
1212, 1170, 1132 (s), 1089, 943 (m), 883 (s), 854 (w), 827 (s), 793, CF ) ppm. IR (KBr): ν = 1674 (m), 1589, 1568, 1510. 1479, 1450
˜
3
775 (w), 713 (s), 640 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 468 (w), 1420 (m), 1329, 1315, 1298, 1271, 1249 (w), 1206 (s), 1162 (m),
(37Cl, 21) [M + H+], 467 (37Cl, 14) [M+], 466 (35Cl, 53) [M + H+],
1130 (s), 1096 (m), 1080, 1038, 1015, 999, 974, 945 (w), 879 (s), 856
2081
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P. Langer et al.
FULL PAPER
(m), 832, 809 (s), 770, 752 (w), 729 (m), 717, 708 (s), 681, 669 (w),
646 (m), 637, 621 (w), 603, 578 (s), 541 (m) cm–1. GC-MS (EI,
70 eV): m/z (%) = 450 (46) [M+], 449 (09), 318 (23), 317 (100), 316
1-(4-Methoxyphenyl)-2-(4-tert-butylphenyl)anthraquinone (6b):
Starting with 2 (252 mg, 0.5 mmol), 3b (76 mg, 0.5 mmol),
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (320 mg,
(14), 260 (10), 233 (20), 231 (14). HRMS (EI, 70 eV): calcd. for 1.5 mmol), 1,4-dioxane (3 mL), and 3c (98 mg, 0.55 mmol), 6b was
1
C21H10O5F4S [M]+ 450.01796; found 450.017099.
isolated as a red solid (111 mg, 50%); m.p. 221–222 °C. H NMR
(300 MHz, CDCl3): δ = 1.18 (s, 9 H, 3ϫCH3), 3.71 (s, 3 H, OCH3),
6.70 (d, J = 8.58 Hz, 2 H, ArH), 6.84 (d, J = 7.26 Hz, 4 H, ArH),
7.10 (d, J = 8.58 Hz, 2 H, ArH), 7.58–7.68 (m, 3 H, ArH), 7.98–
8.01 (m, 1 H, ArH), 8.16–8.20 (m, 1 H, ArH), 8.32 (d, J = 8.58 Hz,
1 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 30.2 (3ϫCH3),
33.4 (C), 54.0 (OCH3), 112.1, 123.5, 125.4, 125.9, 126.3, 128.1,
129.4 (CH), 130.8, 130.9, 131.7 (C), 132.4 (CH), 132.6 (C), 133.0
(CH), 134.1 (C), 134.2 (CH), 136.1, 141.0, 148.3, 149.0, 157.2 (C),
1-(4-Trifluoromethoxyphenyl)-2-[(trifluoromethyl)sulfonyloxy]-
anthraquinone (5h): Starting with 2 (250 mg, 0.5 mmol), 3j (102 mg,
0.5 mmol), [Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4
(160 mg, 0.75 mmol), and 1,4-dioxane (3 mL), 5h was isolated as a
yellow solid (135 mg, 52%); m.p. 108–110 °C. 1H NMR (300 MHz,
CDCl3): δ = 7.17–7.28 (m, 4 H, ArH), 7.66–7.70 (m, 3 H, ArH),
7.96–8.00 (m, 1 H, ArH), 8.16–8.18 (m, 1 H, ArH), 8.43 (d, J =
8.65 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 118.1
(q, JF,C = 320.6 Hz, CF3), 120.5 (q, JF,C = 257.6 Hz, OCF3), 120.8,
126.4, 127.0, 127.6, 129.9, 130.1 (CH), 132.3, 133.3, 134.1, 134.2
(C), 134.3, 134.7 (CH), 135.8, 149.2, 149.3, 151.3 (C), 181.6, 182.0
(CO) ppm. 19F NMR (282 MHz, CDCl3): δ = –74.10 (s, 3 F, CF3),
182.3, 183.0 (CO) ppm. IR (KBr): ν = 2956, 2865, 2839, 2042 (w),
˜
1671 (s), 1658, 1609, 1586 (w), 1573 (m), 1547 (w), 1513 (m), 1477,
1465, 1451, 1439, 1415, 1405, 1390, 1361 (w), 1329, 1315 (m), 1297,
1277, 1241 (s), 1206 (m), 1176 (s), 1159, 1115 (m), 1088, 1071 (w),
1024 (s), 1014 (m), 977 (w), 953 (m), 941, 931, 901, 859 (w), 836
(m), 823 (s), 795 (m), 767, 752, 747 (w), 718 (s), 686, 661 (w), 648
(m), 634 (w), 597, 578, 569 (m), 540 (s) cm–1. GC-MS (EI, 70 eV):
m/z (%) = 446 (100) [M+], 445 (12), 432 (16), 431 (40), 416 (10),
415 (23), 390 (13). 389 (18). HRMS (EI, 70 eV): calcd. for
C31H26O3 [M]+ 446.18765; found 446.187401.
–57.78 (s, 3 F, OCF ) ppm. IR (KBr): ν = 1681 (m), 1609, 1588,
˜
3
1570, 1510, 1450 (w), 1425 (m), 1409, 1329, 1315, 1298 (w), 1250,
1204, 1167, 1152, 1131, 1105 (s), 1081 (m), 1038 (w), 1019 (m), 999
(w), 946 (m), 920 (w), 877 (s), 852 (m), 820 (s), 805 (m), 771 (w),
722, 711 (s), 681, 668, 655 (w), 628 (m), 599 (s), 571, 553, 527
(m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 516 (43) [M+], 431 (10),
384 (22), 383 (100), 382 (13). HRMS (EI, 70 eV): calcd. for
C22H10O6F6S [M]+ 416.00968; found 416.010762.
1-(4-tert-Butylphenyl)-2-[4-(trifluoromethyl)phenyl]anthraquinone
(6c): Starting with 2 (252 mg, 0.5 mmol), 3c (90 mg, 0.5 mmol),
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (320 mg,
1.5 mmol), 1,4-dioxane (3 mL), and 3a (104 mg, 0.55 mmol), 6c
General Procedure for the Synthesis of 6a–f: The reaction was car-
ried out in a pressure tube. To a suspension of 2 (0.5 mmol), Ar1-
B(OH)2 (0.5 mmol), and [Pd(PPh3)4] (3 mol-%) in dioxane (3 mL),
was added K3PO4 (0.75 mmol), and the resultant solution was de-
gassed by bubbling argon through the solution for 10 min. The
mixture was heated at 90 °C under an argon atmosphere for 10 h,
then the mixture was cooled to 20 °C. Ar2B(OH)2 (0.55 mmol),
[Pd(PPh3)4] (3 mol-%), K3PO4 (0.75 mmol), and dioxane (2 mL)
were added and the reaction mixture was heated under an argon
atmosphere for 10 h at 110 °C. The reaction mixture was diluted
with H2O, extracted with CH2Cl2 (3ϫ25 mL) and the combined
organic layers were dried (Na2SO4), filtered, and the filtrate was
concentrated in vacuo. The residue was purified by flash
chromatography (flash silica gel, heptanes/EtOAc).
1
was isolated as a yellow solid (143 mg, 60%); m.p. 220–222 °C. H
NMR (300 MHz, CDCl3): δ = 1.20 (s, 9 H, 3ϫCH3), 6.81 (d, J =
8.59 Hz, 2 H, ArH), 6.98 (d, J = 8.12 Hz, 2 H, ArH), 7.14 (d, J =
8.59 Hz, 2 H, ArH), 7.28 (d, J = 8.12 Hz, 2 H, ArH), 7.60–7.68
(m, 3 H, ArH), 8.00–8.02 (m, 1 H, ArH), 8.17–8.20 (m, 1 H, ArH),
8.36 (d, J = 8.12 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz,
CDCl3): δ = 30.2 (3ϫCH3), 33.4 (C), 122.9 (q, J = 272.2 Hz, CF3),
123.3 (q, JF,C = 7.4, 3.7 Hz), 123.5, 125.6, 126.1, 126.5 (CH), 127.7
(C), 127.8 (CH), 128.2 (C), 128.7 (CH), 130.4, 131.7 (C), 132.6,
133.2, 133.6 (CH), 133.8, 135.1, 141.5, 142.8 (d, J = 1.3 Hz), 146.9,
148.7 (C), 182.1, 182.4 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ
= –62.68 (s, 3 F, CF ) ppm. IR (KBr): ν = 1674 (s), 1615, 1587,
˜
3
1576, 1551, 1511, 1461, 1456, 1415, 1393, 1364, 1359 (w), 1323,
1300 (s), 1283, 1258 (m), 1210, 1198, 1184 (w), 1155, 1109 (s), 1085
(m), 1073, 1061, 1014 (s), 978, 967 (w), 956, 941 (m), 903, 861 (m),
837, 823 (s), 796 (m), 780, 766, 753, 739 (w), 720, 714, 700 (s), 678
(w), 646 (m), 632 (w), 605, 585, 563, 545 (m) cm–1. GC-MS (EI,
70 eV): m/z (%) = 485 (10) [M + H+], 484 (29) [M+], 470 (34), 469
(100), 428 (22), 427 (65). HRMS (EI, 70 eV): calcd. for C31H24F3O2
[M + H]+ 485.1723; found 485.1713.
1-[4-(Trifluoromethyl)phenyl]-2-(4-tert-butylphenyl)anthraquinone
(6a): Starting with 2 (252 mg, 0.5 mmol), 3a (95 mg, 0.5 mmol),
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (320 mg,
1.5 mmol), 1,4-dioxane (3 mL), and 3c (98 mg, 0.55 mmol), 6a was
isolated as yellow crystals (157 mg, 65 %); m.p. 225–227 °C. 1H
NMR (300 MHz, CDCl3): δ = 1.15 (s, 9 H, 3ϫCH3), 6.76–6.80
(m, 2 H, ArH), 7.03–7.10 (m, 4 H, ArH), 7.38 (d, J = 8.1 Hz, 2 H,
ArH), 7.61–7.66 (m, 2 H, ArH), 7.70 (d, J = 8.01 Hz, 1 H, ArH),
7.94–7.98 (m, 1 H, ArH), 8.16–8.20 (m, 1 H, ArH), 8.36 (d, J =
1-(4-Chlorophenyl)-2-(4-tert-butylphenyl)anthraquinone (6d): Start-
8.04 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 31.2 ing with 2 (252 mg, 0.5 mmol), 3d (78 mg, 0.5 mmol), [Pd-
(3ϫCH3), 34.4 (C), 124.3 (q, JF,C = 272.3 Hz, CF3), 124.4 (dq, JF,C
= 7.6, 2.2 Hz), 124.7, 126.7, 127.4, 127.6 (CH), 128.5 (q, J = 1.5 mmol), 1,4-dioxane (3 mL), and 3c (98 mg, 0.55 mmol), 6d was
32.8 Hz, 1 C), 129.0, 129.7 (CH), 131.3, 132.8, 133.6 (C), 133.8,
isolated as a yellow solid (137 mg, 61 %); m.p. 245–246 °C. 1H
134.3 (CH), 134.6 (C), 135.4 (CH), 136.3, 140.8, 144.0 (d, J = NMR (300 MHz, CDCl3): δ = 1.30 (s, 9 H, 3ϫCH3), 6.92–7.00
(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (320 mg,
1.7 Hz), 149.1, 150.5 (C), 183.0, 183.6 (CO) ppm. 19F NMR
(282 MHz, CDCl ): δ = –62.3 (s, 3 F, CF ) ppm. IR (KBr): ν =
2962, 2905, 2869 (w), 1672 (m), 1613, 1588, 1552, 1513, 1462, 1409,
(m, 4 H, ArH), 7.21–7.26 (m, 4 H, ArH), 7.75–7.82 (m, 3 H, ArH),
8.09–8.12 (m, 1 H, ArH), 8.30–8.33 (m, 1 H, ArH), 8.48 (d, J =
7.46 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 31.2
˜
3
3
1399, 1363 (w), 1321 (s), 1300, 1278, 1263 (m), 1213, 1186 (w), 1158 (3ϫCH3), 34.5 (C), 124.7, 126.6, 127.3, 127.4, 128.0, 129.1, 130.7
(s), 1118 (m), 1105 (s), 1087, 1075, 1059, 1016 (m), 976 (w), 954 (CH), 131.6, 132.5, 132.7, 133.6 (C), 133.7, 134.2 (CH), 134.8 (C),
(m), 899, 864 (w), 837, 824 (m), 796, 784, 767, 758, 744 (w), 718 135.5 (CH), 136.6, 138.4, 141.0, 149.1, 150.3 (C), 183.1, 183.8
(s), 688, 671, 662, 640, 605 (w), 584 (m), 566, 564, 532 (w) cm–1. (CO) ppm. IR (KBr): ν = 1667 (s), 1588, 1575, 1549, 1513, 1492,
˜
GC-MS (EI, 70 eV): m/z (%) = 484 (43) [M+], 469 (100), 449 (10), 1477, 1461, 1409, 1391, 1360 (w), 1332 (m), 1316 (w), 1298 (m),
427 (08), 383 (02), 357 (03). HRMS (EI, 70 eV): calcd. for 1277 (w), 1261 (m), 1247, 1212, 1184, 1159, 1112, 1087, 1071 (w),
C31H23O2F3 [M]+ 484.16447; found 484.164850.
1013 (m), 981 (w), 954 (m), 941, 905, 858, 842 (w), 832, 825 (m),
2082
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2075–2087

Site-Selective Arylation of Alizarin and Purpurin
794, 774, 763, 746 (w), 720 (s), 697, 691, 679, 643, 630 (w), 583, 1,2,4-Tris[(trifluoromethyl)sulfonyloxy]anthraquinone (8): Starting
576 (m), 549, 533 (w) cm–1. GC-MS (EI, 70 eV): m/z (%) = 452 with 1,2,4-trihydroxyanthraquinone 7 (1.00 g, 3.90 mmol), pyridine
(37Cl, 16) [M+], 451 (35Cl, 19) [M + H+], 450 (35Cl, 46) [M+], 437 (2.2 mL, 27.3 mmol), CH2Cl2 (40 mL), Tf2O (3.3 mL, 19.5 mmol),
(38), 436 (31), 435 (100), 393 (14), 207 (10). HRMS (EI, 70 eV):
8 was isolated as a yellow solid (1.10 g, 43%); m.p. 162–164 °C. 1H
calcd. for C30H24ClO2 ([M + H]+, 35Cl) 451.1459; found 451.1459. NMR (300 MHz, CDCl3): δ = 7.66 (s, 1 H, ArH), 7.80–7.86 (m, 2
H, ArH), 8.22–8.36 (m, 2 H, ArH) ppm. 13C NMR (62.9 MHz,
1-(3-Trifluoromethylphenyl)-2-[4-(trifluoromethyl)phenyl]anthra-
CDCl3): δ = 118.3 (d, JF,C1 = 313.5 Hz, CF3), 118.4 (d, JF,C
=
quinone (6e): Starting with 2 (252 mg, 0.5 mmol), 3g (95 mg,
0.5 mmol), [Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4
(320 mg, 1.5 mmol), 1,4-dioxane (3 mL), and 3a (104 mg,
0.55 mmol), 6e was isolated as a yellow solid (169 mg, 68%); m.p.
255–256 °C. 1H NMR (300 MHz, CDCl3): δ = 7.02 (d, J = 8.23 Hz,
2 H, ArH), 7.14 (d, J = 7.65 Hz, 1 H, ArH), 7.27–7.45 (m, 5 H,
ArH), 7.65–7.77 (m, 3 H, ArH), 8.00–8.03 (m, 1 H, ArH), 8.23–
8.26 (m, 1 H, ArH), 8.46 (d, J = 8.10 Hz, 1 H, ArH) ppm. 13C
NMR (62.9 MHz, CDCl3): δ = 122.8 (q, JF,C = 321.2 Hz, CF3),
123.1 (q, JF,C = 272.0 Hz, CF3), 123.6 (d, J = 4.1 Hz), 124.8 (d, J
= 3.7 Hz), 126.2 (d, J = 3.8 Hz), 126.8, 127.4, 127.8, 128.2, 129.7
(CH), 130.0, 130.5, 131.5 (C), 132.5 (CH), 132.6 (C), 134.0 (CH),
134.3 (C), 134.4 (CH), 134.6 (C), 134.9 (CH), 140.1, 140.5, 143.0,
316.0 Hz, CF3), 118.6 (d, JF,C = 319.0 Hz, CF3), 123.3 (CH), 126.8
(C), 127.7, 127.8 (CH), 129.6, 132.5, 132.6 (C), 135.5, 135.6 (CH),
138.9, 144.5, 146.6 (C), 178.4, 179.9 (CO) ppm. 19F NMR
(282 MHz, CDCl3): δ = –73.02 (q, JF = 2.82, 5.28 Hz, 3 F, CF3),
–72.83 (s, 3 F, CF3), –72.24 (q, JF = 2.73, 5.07 Hz, 3 F, CF3) ppm.
IR (KBr): ν = 3100 (w), 1682 (s), 1589 (m), 1440, 1428 (s), 1310
˜
(m), 1278 (w), 1208, 1182, 1170, 1127 (s), 1071, 1039, 1018 (m),
974 (w), 929, 904, 851, 812, 780, 763 (s), 756, 740 (m), 719 (s), 712,
695, 674 (m), 653, 635 (s), 623 (m), 597, 534 (s) cm–1. GC-MS (EI,
70 eV): m/z (%) = 652 (100) [M+], 583 (13), 519 (11), 455 (46), 427
(16), 391 (14), 363 (85), 336 (11), 335 (74). HRMS (EI, 70 eV):
calcd. for C17H5F9O11S3 [M]+ 651.88448; found 651.883916.
147.6 (C), 182.8, 183.3 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ General Procedure for Suzuki–Miyaura Reactions: A 1,4-dioxane
= –62.79 (s, 3 F, CF ), –62.78 (s, 3 F, CF ) ppm. IR (KBr): ν =
solution (4 mL per 3 mmol of 8) of 8, K3PO4, [Pd(PPh3)4], and
arylboronic acid 3, was stirred at 110 °C or 90 °C for 10 h. After
cooling to 20 °C, distilled water was added, the organic and the
aqueous layers were separated and the latter was extracted with
˜
3
3
1669 (s), 1617, 1589, 1574, 1533, 1490, 1432, 1414, 1399 (w), 1328,
1302 (s), 1285, 1263, 1244, 1291, 1212 (w), 1161, 1109, 1081, 1066
(s), 1018 (m), 1002, 981 (w), 961 (m), 923, 893, 863 (w), 849 (m),
836 (w), 825, 805 (m), 792, 767, 752, 746, 725 (w), 712, 706 (s), 686 CH2Cl2. The combined organic layers were dried (Na2SO4), fil-
(w), 675 (m), 655, 629, 605, 567, 542 (w) cm–1. GC-MS (EI, 70 eV):
tered, and the filtrate was concentrated in vacuo. The residue was
m/z (%) = 496 (80) [M+], 495 (100), 477 (09), 428 (21), 427 (72), purified by column chromatography (flash silica gel, heptanes/
407 (08). HRMS (EI, 70 eV): calcd. for C28H13O2F6 [M – H]+
495.08143; found 495.080798.
EtOAc).
1,2,4-Tris[4-(trifluoromethyl)phenyl]anthraquinone (9a): Starting
1-(3-Trifluoromethylphenyl)-2-(4-tert-butylphenyl)anthraquinone with 8 (100 mg, 0.15 mmol), 3a (114 mg, 0.6 mmol), [Pd(PPh3)4]
(6f): Starting with 2 (252 mg, 0.5 mmol), 3g (95 mg, 0.5 mmol), (17 mg, 10 mol-%, 0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and
[Pd(PPh3)4] (17 mg, 3 mol-%, 0.015 mmol), K3PO4 (320 mg, 1,4-dioxane (5 mL), 9a was isolated as a yellow solid (43 mg, 43%);
1
1.5 mmol), 1,4-dioxane (3 mL), and 3c (98 mg, 0.55 mmol), 6f was m.p. 237–238 °C. H NMR (300 MHz, CDCl3): δ = 7.03–7.12 (m,
isolated as a yellow solid (148 mg, 61 %); m.p. 227–229 °C. 1H
4 H, ArH), 7.35–7.47 (m, 6 H, ArH), 7.48 (s, 1 H, ArH), 7.64–7.67
NMR (300 MHz, CDCl3): δ = 1.16 (s, 9 H, 3ϫCH3), 6.75 –6.77 (m, 4 H, ArH), 7.94–8.02 (m, 2 H, ArH) ppm. 13C NMR
(m, 2 H, ArH), 7.07–7.10 (m, 3 H, ArH), 7.17 (d, J = 8.34 Hz, 1 (62.9 MHz, CDCl3): δ = 123.7 (q, JF,C = 272.3 Hz, CF3), 124.0 (q,
H, ArH), 7.27 (t, J = 7.68 Hz, 1 H, ArH), 7.40 (d, J = 7.86 Hz, 1 JF,C = 272.1 Hz, CF3), 124.2 (q, JF,C = 272.1 Hz, CF3), 124.9 (t, J
H, ArH), 7.60–7.70 (m, 2 H, ArH), 7.73 (d, J = 7.86 Hz, 1 H,
ArH), 7.96–8.00 (m, 1 H, ArH), 8.18–8.21 (m, 1 H, ArH), 8.37 (d,
J = 8.04 Hz, 1 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ =
= 3.5 Hz), 125.0, 125.2 (d, J = 3.8 Hz), 126.8, 127.0, 128.3 (CH),
128.9 (C), 129.4, 129.6 (CH), 129.8, 130.1, 132.1, 133.4, 133.7,
133.9 (C), 134.1, 134.2, 138.0 (CH), 140.8, 142.4, 143.0, 143.1,
30.1 (3ϫCH3), 33.4 (C), 122.2 (q, JF,C = 3.84 Hz, CH), 122.9 (q, 145.4, 146.2 (C), 183.2, 183.7 (CO) ppm. 19F NMR (282 MHz,
J = 272.4 Hz, CF3), 123.6, 125.3 (q, J = 3.8 Hz), 125.6, 126.3,
126.5, 126.7, 128.0 (CH), 128.7, 129.1, 130.4, 131.7 (C), 131.9
CDCl3): δ = –62.77 (s, 3 F, CF3), –62.41 (s, 3 F, CF3), –62.38 (s, 3
F, CF ) ppm. IR (KBr): ν = 3067, 2929, 2581 (w), 1673 (m), 1616,
˜
3
(CH), 132.6 (C), 132.7, 133.2 (CH), 133.7 (C), 134.2 (CH), 135.2, 1592, 1531, 1407, 1372 (w), 1323 (s), 1285, 1251 (m), 1211 (w),
139.6 (d, J = 9.8 Hz), 148.3, 149.4 (C), 182.0, 182.6 (CO) ppm. 19
NMR (282 MHz, CDCl3): δ = –62.68 (s, 3 F, CF3) ppm. IR (KBr):
˜
1479, 1460, 1433, 1407, 1393, 1365 (w), 1329, 1316, 1302 (s), 1279
(m), 1258, 1245 (s), 1211, 1183 (w), 1159, 1116, 1100, 1068 (s), 1017
(m), 1001, 986, 973 (w), 961 (m), 917, 892 (w), 861, 838 (m), 824,
801 (s), 792 (m), 768, 751, 744 (w), 715, 702 (s), 688 (w), 679, 666,
652 (m), 628 (w), 580, 566, 545 (m) cm–1. GC-MS (EI, 70 eV): m/z
(%) = 484 (43) [M+], 470 (33), 469 (100). HRMS (EI, 70 eV): calcd.
for C31H23O2F3 [M]+ 484.16447; found 484.164011.
F
1167, 1108 (s), 1089 (m), 1081, 1060, 1017 (s), 966 (m), 937, 919,
866 (w), 839 (m), 801, 766, 746 (w), 726 (m), 711, 684, 660, 644,
ν = 2957, 2907, 2872, 2134 (w), 1671 (s), 1589, 1574, 1549, 1513, 622, 604, 551, 539 (w) cm–1. GC-MS (EI, 70 eV): m/z (%) = 640
(98) [M+], 639 (100), 638 (13), 621 (15), 572 (28), 571 (81), 570 (36).
HRMS (EI, 70 eV): calcd. for C35H16F9O2 [M – H]+ 639.10011;
found 639.099492.
1,2,4-Tris(4-methoxyphenyl)anthraquinone (9b): Starting with 8
(100 mg, 0.15 mmol), 3b (91 mg, 0.6 mmol), [Pd(PPh3)4] (17 mg,
10 mol-%, 0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and 1,4-diox-
ane (5 mL), 9b was isolated as an orange solid (59 mg, 73%); m.p.
240–242 °C. 1H NMR (300 MHz, CDCl3): δ = 3.67 (s, 3 H, OCH3),
3.74 (s, 3 H, OCH3), 3.80 (s, 3 H, OCH3), 6.61–6.64 (m, 2 H, ArH),
6.72–6.75 (m, 2 H, ArH), 6.85–6.90 (m, 6 H, ArH), 7.21–7.24 (m,
2 H, ArH), 7.49 (s, 1 H, ArH), 7.58–7.61 (m, 2 H, ArH), 7.93–8.01
(m, 2 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 55.0, 55.1,
55.2 (OCH3), 113.2, 113.3, 113.6, 126.5, 126.6, 129.3, 130.5, 130.7
(CH), 131.3, 132.1, 132.2 (C), 133.5, 133.6 (CH), 134.0, 134.3,
134.4, 134.5 (C), 138.8 (CH), 141.2, 143.3, 147.5, 158.2, 158.6,
1,2,4-Tris[(trifluoromethyl)sulfonyloxy]anthraquinone (8): To a solu-
tion of 7 (1.0 equiv.) in CH2Cl2 (10 mL/mmol), was added pyridine
(7.0 equiv.) at room temperature under an argon atmosphere. After
10 min, Tf2O (5.0 equiv.) was added at –78 °C and the mixture was
warmed to room temperature and stirred overnight. The reaction
mixture was filtered and the filtrate was concentrated in vacuo. The
products of the reaction mixture were isolated by rapid column
chromatography (flash silica gel, heptanes/EtOAc).
Eur. J. Org. Chem. 2011, 2075–2087
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2083

P. Langer et al.
158.9 (C), 184.1, 185.0 (CO) ppm. IR (KBr): ν = 3318, 3068, 3033, 114.7, 114.8, 115.0, 115.1, 115.2, 115.3, 126.6, 126.8, 129.6, 129.7,
FULL PAPER
˜
3012, 2952, 2918, 2849, 2833, 2539 (w), 1665, 1606 (s), 1592, 1575
(m), 1508 (s), 1461, 1454, 1435 (m), 1410, 1368 (w), 1330, 1310 (m),
1289, 1239, 1173 (s), 1107, 1085, 1076 (m), 1027, 1010, 963 (s), 938
(m), 917, 907, 862 (w), 829, 802, 796 (s), 773, 763 (m), 749 (w), 736
(m), 722 (s), 686 (w), 653, 645, 628, 621 (m), 594 (w), 572 (m), 548
(s) cm–1. GC-MS (EI, 70 eV): m/z (%) = 526 (100) [M+], 525 (40),
495 (15), 285 (12). HRMS (EI, 70 eV): calcd. for C35H26O5 [M]+
526.17748; found 526.176367.
130.7, 130.8, 131.0, 131.1 (CH), 131.8, 133.8 (C), 133.8, 133.9
(CH), 133.9, 134.2, 135.2 (d, J = 3.3 Hz), 135.5 (d, J = 3.6 Hz),
137.7 (d, J = 3.6 Hz, 1 C), 138.5 (CH), 140.9, 143.0, 146.9, 161.7
(d, JF,C = 246.4 Hz), 161.9 (d, JF,C = 248.0 Hz), 162.2 (d, JF,C
=
246.6 Hz, CF), 183.7, 184.3 (CO) ppm. 19F NMR (282 MHz,
CDCl3): δ = –115.07 (s, 1 F, CF), –114.85 (s, 1 F, CF), –114.14 (s,
1 F, CF) ppm. IR (KBr): ν = 3069, 3041, 2920, 2852 (w), 1673 (s),
˜
1604 (w), 1592 (m), 1530 (w), 1510 (s), 1442, 1402, 1370 (w), 1328,
1308 (m), 1278 (w), 1245 (m), 1222, 1157 (s), 1092, 1083, 1073,
1014 (w), 963 (m), 945, 927, 866 (w), 829, 817 (s), 804 (m), 786,
766, 745 (w), 734, 721 (m), 709, 701, 686, 658, 650, 642, 624, 617,
587, 560 (w), 551 (m), 534 (w) cm–1. GC-MS (EI, 70 eV): m/z (%)
= 490 (83) [M+], 489 (100), 488 (18), 394 (18). HRMS (EI, 70 eV):
calcd. for C32H17O2F3 [M+] 490.11752; found 490.116052.
1,2,4-Tris(4-tert-butylphenyl)anthraquinone (9c): Starting with 8
(100 mg, 0.15 mmol), 3c (107 mg, 0.6 mmol), [Pd(PPh3)4] (17 mg,
10 mol-%, 0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and 1,4-diox-
ane (5 mL), 9c was isolated as an orange solid (77 mg, 83%); m.p.
244–246 °C. 1H NMR (300 MHz, CDCl3): δ = 1.13 (s, 9 H,
3ϫCH3), 1.20 (s, 9 H, 3ϫCH3), 1.31 (s, 9 H, 3ϫCH3), 6.75–6.76
(m, 2 H, ArH), 6.84–6.87 (m, 2 H, ArH), 6.99–7.02 (m, 2 H, ArH), 1,2,4-Triphenylanthraquinone (9f): Starting with 8 (100 mg,
7.12–7.15 (m, 2 H, ArH), 7.21–7.24 (m, 2 H, ArH), 7.36–7.39 (m,
2 H, ArH), 7.53 (s, 1 H, ArH), 7.55–7.58 (m, 2 H, ArH), 7.93–8.03
0.15 mmol), 3k (73 mg, 0.6 mmol), [Pd(PPh3)4] (17 mg, 10 mol-%,
0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and 1,4-dioxane (5 mL),
(m, 2 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 31.2, 31.4, 9f was isolated as a yellow solid (58 mg, 86%); m.p. 228–230 °C.
31.5 (9ϫCH3), 34.3, 34.4, 34.6, 124.2, 124.4, 125.0, 126.6, 126.8, 1H NMR (300 MHz, CDCl3): δ = 6.92–7.00 (m, 4 H, ArH), 7.06
127.7, 127.9, 128.6 (C), 129.0 (CH), 131.4 (C), 133.5, 133.5 (CH), (t, J = 2.61 Hz, 3 H, ArH), 7.16–7.18 (m, 3 H, ArH), 7.28–7.38 (m,
133.6, 134.0, 134.4, 136.8, 137.1 (C), 138.8 (CH), 139.3, 142.0,
5 H, ArH), 7.52 (s, 1 H, ArH), 7.57–7.60 (m, 2 H, ArH), 7.93–8.01
143.7, 148.2, 149.1, 149.8 (C), 184.1, 184.6 (CO) ppm. IR (KBr): ν
(m, 2 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 126.5,
˜
= 2952 (s), 2902, 2864 (m), 1677, 1669 (s), 1607 (w), 1592 (m), 126.6, 126.8, 127.1, 127.2, 127.6, 127.7, 128.0, 128, 129.3, 129.4
1574, 1512, 1504, 1475 (w), 1462 (m), 1440, 1392 (w), 1360 (m), (CH), 131.6 (C), 133.6, 133.7 (CH), 133.8, 133.9, 134.4 (C), 138.6
1327 (s), 1309, 1301, 1279, 1266 (m), 1241 (s), 1212, 1201, 1165, (CH), 139.6, 139.9, 141.8, 142.2, 143.8, 147.7 (C), 183.8, 184.5
1155 (w), 1114, 1081, 1016, 966 (m), 944, 934, 918, 898, 863 (w), (CO) ppm. IR (KBr): ν = 3329, 3065, 3054, 3022, 2953, 2919, 2850
˜
831 (s), 796 (m), 772, 764, 740 (w), 725 (s), 705, 681 (w), 651, 625
(w), 1677 (s), 1633 (w), 1590 (m), 1557, 1537, 1524, 1494, 1455,
(m), 615 (w), 580 (m), 567 (s), 551 (m) cm–1. GC-MS (EI, 70 eV): 1443, 1431, 1370 (w), 1322, 1302 (s), 1277 (m), 1243 (s), 1206, 1160
m/z (%) = 604 (31) [M+], 590 (11), 589 (24), 548 (14), 547 (33), 532 (w), 1085, 1077, 1071 (m), 1034 (w), 1024 (m), 1001, 975 (w), 959
(03), 490 (04), 287 (11), 69 (06), 57 (100). HRMS (EI, 70 eV): calcd.
(m), 938, 915, 899, 857, 842, 825 (w), 801, 774, 760, 750, 742 (m),
728 (s), 711 (m), 691 (s), 671 (m), 652 (s), 637, 614, 570 (m), 554
(w), 541 (s) cm–1. GC-MS (EI, 70 eV): m/z (%) = 436 (78) [M+],
435 (100), 434 (18), 358 (19), 218 (19), 217 (44). HRMS (EI, 70 eV):
calcd. for C32H19O2 [M – H]+ 435.13796; found 435.137591.
for C44H44O2 [M]+ 604.33358; found 604. 33345.
1,2,4-Tris(4-chlorophenyl)anthraquinone (9d): Starting with 8
(100 mg, 0.15 mmol), 3d (94 mg, 0.6 mmol), [Pd(PPh3)4] (17 mg,
10 mol-%, 0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and 1,4-diox-
ane (5 mL), 9d was isolated as a yellow solid (50 mg, 60%); m.p.
1,4-Bis[4-(trifluoromethyl)phenyl]-2-[(trifluoromethyl)sulfonyloxy]-
anthraquinone (10a): Starting with 8 (100 mg, 0.15 mmol), 3a
(57 mg, 0.3 mmol), [Pd(PPh3)4] (10 mg, 6 mol-%, 0.009 mmol),
1
293–295 °C. H NMR (300 MHz, CDCl3): δ = 6.84–6.92 (m, 4 H,
ArH), 7.07–7.11 (m, 2 H, ArH), 7.18–7.23 (m, 4 H, ArH), 7.34–
7.38 (m, 2 H, ArH), 7.44 (s, 1 H, ArH), 7.62–7.65 (m, 2 H, ArH), K3PO4 (96 mg, 0.45 mmol), and 1,4-dioxane (4 mL), 10a was iso-
7.93–8.01 (m, 2 H, ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ =
126.7, 126.8, 128.2, 128.2, 128.4, 129.3, 130.5, 130.6 (CH), 131.9,
132.9, 133.5, 133.7, 133.8 (C), 133.9, 134.0 (CH), 134.1, 137.5,
138.0 (C), 138.3 (CH), 141.2, 140.2, 140.7, 142.9, 145.5 (C), 183.8,
lated as an orange solid (61 mg, 61%); m.p. 168–170 °C. 1H NMR
(300 MHz, CDCl3): δ = 7.32–7.40 (m, 4 H, ArH), 7.48 (s, 1 H,
ArH), 7.66–7.72 (m, 6 H, ArH), 7.94–8.00 (m, 2 H, ArH) ppm. 13
C
NMR (62.9 MHz, CDCl3): δ = 118.0 (q, JF,C = 320.4 Hz, CF3),
119.7 (q, JF,C = 272.2 Hz, CF3), 125.4 (t, J = 3.8 Hz), 127.0, 127.1,
128.1 (CH), 128.5 (q, JF,C = 286.2 Hz, CF3), 128.9, 129.2 (CH),
129.9, 130.2, 130.4, 132.2, 133.2, 133.3 (C), 134.5, 134.6 (CH),
135.3, 135.7, 137.7, 143.9, 145.6, 149.6 (C), 182.2, 182.2 (CO) ppm.
19F NMR (282 MHz, CDCl3): δ = –73.86 (s, 3 F, CF3), –62.59 (s,
184.1 (CO) ppm. IR (KBr): ν = 3320, 3065, 2923, 2853 (w), 1670
˜
(s), 1650, 1644, 1632 (w), 1591 (m), 1524 (w), 1492 (s), 1470, 1441,
1397, 1370 (w), 1328 (m), 1311 (s), 1282 (m), 1247 (s), 1209, 1158
(w), 1089, 1013, 962 (s), 935, 918, 862 (w), 818 (s), 810, 766 (m),
733 (s), 718 (m), 700, 687, 671, 656 (w), 647 (m), 636, 618, 593 (w),
551 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 542 (2ϫ37Cl, 29)
3 F, CF ), –62.51 (s, 3 F, CF ) ppm. IR (KBr): ν = 2917 (w), 1675
˜
3
3
[M+], 541 (37Cl, 50) [M + H+], 540 (37Cl, 92) [M+], 539 (35Cl, 100) (m), 1618, 1591, 1541, 1428, 1408 (w), 1321 (s), 1241 (m), 1217 (s),
[M + H+], 538 (35Cl, 93) [M+], 537 (78), 505 (24), 504 (26), 503 1190 (w), 1163 (m), 1122, 1108, 1080, 1059 (s), 1040 (w), 1017, 948,
(37), 502 (25). HRMS (EI, 70 eV): calcd. for C32H17Cl3O2 ([M]+,
37Cl) 540.02591; found 540.024908, C32H17Cl3O2 ([M]+, 2ϫ37Cl):
542.02296; found 542.023142.
900 (m), 854 (w), 834, 823, 799, 786, 763, 753, 744 (s), 731 (m),
713, 692, 682, 662, 641, 630 (w), 599 (s), 571, 535 (w) cm–1. GC-
MS (EI, 70 eV): m/z (%) = 644 (100) [M+], 643 (68), 625 (11), 576
(14), 575 (48), 512 (21), 511 (56), 510 (29), 509 (13). HRMS (EI,
70 eV): calcd. for C29H13F9O5S [M]+ 644.03345; found 644.03239.
1,2,4-Tris(4-fluorophenyl)anthraquinone (9e): Starting with 8
(100 mg, 0.15 mmol), 3i (84 mg, 0.6 mmol), [Pd(PPh3)4] (17 mg,
10 mol-%, 0.015 mmol), K3PO4 (159 mg, 0.75 mmol), and 1,4-diox- 1,4-Bis(4-tert-butylphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthra-
ane (5 mL), 9e was isolated as orange crystals (43 mg, 57%); m.p.
204–206 °C. H NMR (300 MHz, CDCl3): δ = 6.77–6.83 (m, 2 H,
quinone (10b): Starting with 8 (100 mg, 0.15 mmol), 3c (54 mg,
0.3 mmol), [Pd(PPh3)4] (10 mg, 6 mol-%, 0.009 mmol), K3PO4
1
ArH), 6.86–6.93 (m, 6 H, ArH), 7.04–7.11 (m, 2 H, ArH), 7.23–
(96 mg, 0.45 mmol), and 1,4-dioxane (4 mL), 10b was isolated as a
1
7.27 (m, 2 H, ArH), 7.47 (s, 1 H, ArH), 7.61–7.64 (m, 2 H, ArH), yellow solid (77 mg, 81%); m.p. 245–247 °C. H NMR (300 MHz,
7.93–8.01 (m, 2 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ =
CDCl3): δ = 0.59 (s, 9 H, 3ϫCH3), 0.60 (s, 9 H, 3ϫCH3), 6.37–
2084
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2075–2087

Site-Selective Arylation of Alizarin and Purpurin
6.40 (m, 2 H, ArH), 6.46–6.48 (m, 2 H, ArH), 6.68–6.74 (m, 4 H,
ArH), 6.74 (s, 1 H, ArH), 6.86–6.90 (m, 2 H, ArH), 7.21–7.27 (m,
1,4-Bis(3,5-dimethylphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthra-
quinone (10e): Starting with 8 (100 mg, 0.15 mmol), 3l (45 mg,
2 H, ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 31.3, 31.4 0.3 mmol), [Pd(PPh3)4] (10 mg, 6 mol-%, 0.009 mmol), K3PO4
(6ϫCH3), 34.7, 34.8 (C), 117.5 (q, JF,C = 318.5 Hz, CF3), 125.2,
125.3, 126.8, 127.0, 127.6, 128.3, 129.5 (CH), 130.8, 132.3, 133.7,
133.8 (C), 133.9, 134.0 (CH), 135.5, 136.5, 137.5, 146.5, 150.1,
150.8, 151.0 (C), 182.8, 182.9 (CO) ppm. 19F NMR (282 MHz,
(96 mg, 0.45 mmol), and 1,4-dioxane (4 mL), 10e was isolated as a
yellow solid (52 mg, 60%); m.p. 211–213 °C. H NMR (300 MHz,
1
CDCl3): δ = 2.31 (s, 6 H, 2ϫCH3), 2.32 (s, 6 H, 2ϫCH3), 6.79
(br. m, 2 H, ArH), 6.86 (br. m, 2 H, ArH), 7.03 (br. m, 2 H, ArH),
7.44 (s, 1 H, ArH), 7.61–7.64 (m, 2 H, ArH), 7.96–7.99 (m, 2 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 21.4, 21.4
(4 ϫCH3), 118.1 (q, JF,C = 320.2 Hz, CF3), 125.5, 126.2, 126.9,
CDCl ): δ = –74.69 (s, 3 F, CF ) ppm. IR (KBr): ν = 2965 (m),
˜
3
3
2867 (w), 1677 (s), 1590, 1536, 1531, 1513, 1462 (w), 1425 (s), 1404,
1360 (w), 1319 (s), 1268 (m), 1239, 1214 (s), 1177 (m), 1159 (w),
1137, 1115 (s), 1040, 1015, 1004, 977, 966 (w), 947, 900, 844, 825, 127.0, 129.1, 129.6, 129.8 (CH), 132.2, 133.7, 133.7, 133.8 (C),
812, 803 (s), 776 (w), 746 (m), 732, 722 (s), 699 (w), 686 (m), 661 134.0, 134.1 (CH), 135.3, 136.8, 137.7, 137.9, 140.5, 146.7, 149.9
(w), 642 (m), 608 (s), 597 (m), 566 (s), 528 (m) cm–1. GC-MS (EI,
(C), 182.7, 182.8 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ =
70 eV): m/z (%) = 620 (06) [M+], 606 (13), 605 (34), 565 (10), 564 –74.51 (s, 3 F, CF ) ppm. IR (KBr): ν = 3005, 2916, 2861 (w), 1674
˜
3
(32), 563 (100), 571 (09), 457 (10). HRMS (EI, 70 eV): calcd. for
(s), 1593, 1537, 1442, 1427 (w), 1405 (m), 1371 (w), 1331, 1294 (m),
1267 (w), 1240 (m), 1206 (s), 1173, 1162 (m), 1134, 1026, 1010 (s),
968 (m), 920, 898, 883 (w), 848, 814, 796 (s), 771, 752 (w), 729, 723
(s), 708 (w), 692, 648, 631, 604 (s), 570, 552, 530 (m) cm–1. GC-MS
(EI, 70 eV): m/z (%) = 564 (66) [M+], 550 (22), 549 (80), 432 (14),
431 (49), 430 (21), 417 (34), 416 (86), 415 (36), 402 (16), 401 (57),
387 (14), 215 (14), 208 (100), 207 (15). HRMS (EI, 70 eV): calcd.
for C31H23F3O5S [M]+ 564.12128; found 564.122443.
C35H31F3O5S [M]+ 620.18388; found 620.183785.
1,4-Bis(4-methyllphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthra-
quinone (10c): Starting with 8 (100 mg, 0.15 mmol), 3e (41 mg,
0.3 mmol), [Pd(PPh3)4] (10 mg, 6 mol-%, 0.009 mmol), K3PO4
(96 mg, 0.45 mmol), and 1,4-dioxane (4 mL), 10c was isolated as a
1
yellow solid (42 mg, 51%); m.p. 186–188 °C. H NMR (300 MHz,
CDCl3): δ = 2.39 (s, 3 H, CH3), 2.40 (s, 3 H, CH3), 7.07–7.10 (m,
2 H, ArH), 7.14–7.17 (m, 2 H, ArH), 7.22–7.26 (m, 4 H, ArH),
7.46 (s, 1 H, ArH), 7.59–7.66 (m, 2 H, ArH), 7.94–7.98 (m, 2 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 21.4, 21.5 (CH3),
118.1 (q, JF,C = 320.7 Hz, CF3), 126.9, 127.0, 127.8, 128.5, 129.1,
129.2, 129.3 (CH), 130.8, 132.4, 133.7, 133.8 (C), 134.0, 134.1
(CH), 135.5, 136.7, 137.6, 137.8, 137.9, 146.5, 150.1 (C), 182.8,
182.9 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ = –73.96 (s, 3 F,
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(4-methoxyphenyl)anthra-
quinone (11a): Starting with 8 (100 mg, 0.15 mmol), 3b (23 mg,
0.15 mmol), [Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol), K3PO4
(48 mg, 0.225 mmol), and 1,4-dioxane (3 mL), 11a was isolated as
a red solid (36 mg, 38 %); m.p. 87–88 °C. 1H NMR (300 MHz,
CDCl3): δ = 3.82 (s, 3 H, OCH3), 6.91–6.93 (m, 1 H, ArH), 6.94–
6.96 (m, 1 H, ArH), 7.13–7.14 (m, 1 H, ArH), 7.16–7.18 (m, 1 H,
ArH), 7.59 (s, 1 H, ArH), 7.69–7.78 (m, 2 H, ArH), 7.99–8.01 (m,
1 H, ArH), 8.21–8.24 (m, 1 H, ArH) ppm. 13C NMR (62.9 MHz,
CDCl3): δ = 55.3 (OCH3), 114.0 (CH), 115.9 (q, JF,C = 318.4 Hz,
CF3), 121.0 (q, JF,C = 320.2 Hz, CF3), 127.2, 127.4, 129.2 (CH),
129.3 (C), 131.1 (CH), 131.2, 131.9, 132.9, 133.4 (C), 134.5, 135.0
(CH), 138.1, 143.1, 146.2, 159.9 (C), 181.1, 181.4 (CO) ppm. 19F
NMR (282 MHz, CDCl3): δ = –73.33 (q, JF = 5.33, 2.45 Hz, 3 F,
CF ) ppm. IR (KBr): ν = 3022, 2960, 2920, 2860 (w), 1675 (s),
˜
3
1651, 1592, 1538, 1515, 1446 (w), 1420 (s), 1403, 1379 (w), 1312
(m), 1272, 1261 (w), 1239 (m), 1220, 1205 (s), 1161 (w), 1131 (s),
1037, 1019, 1005, 962 (w), 946, 896 (s), 848 (m), 829, 819, 810, 798
(s), 769 (w), 752 (m), 729 (s), 715 (m), 689, 659, 650, 631 (w), 599
(s), 570, 558, 538, 530 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) =
536 (85) [M+], 535 (23), 523 (10), 522 (26), 521 (100), 404 (10), 403
(48), 402 (33), 401 (20), 389 (18), 388 (77), 387 (61), 386 (27).
HRMS (EI, 70 eV): calcd. for C29H19F3O5S [M]+ 536.08998; found
536.090080.
CF3), –72.56 (q, JF = 5.70, 2.79 Hz, 3 F, CF ) ppm. IR (KBr): ν =
˜
3
2961, 2916, 2840 (w), 1680 (s), 1607, 1593, 1579, 1513 (w), 1432
(s), 1323 (m), 1303 (w), 1243, 1204, 1177, 1168, 1126 (s), 1044, 1030
(m), 1013, 996 (s), 905 (w), 865, 830, 805, 784, 760, 723 (s), 684,
654, 644, 622 (m), 593, 579 (s), 534 (m) cm–1. GC-MS (EI, 70 eV):
m/z (%) = 610 (100) [M + H+], 479 (10), 478 (27), 477 (82), 385
(10), 346 (12), 345 (24), 317 (28), 316 (93), 315 (10). HRMS (EI,
70 eV): calcd. for C23H12F6O9S2 [M]+ 609.98214; found
609.981630.
1,4-Bis(4-ethyllphenyl)-2-[(trifluoromethyl)sulfonyloxy]anthra-
quinone (10d): Starting with 8 (100 mg, 0.15 mmol), 3f (45 mg,
0.3 mmol), [Pd(PPh3)4] (10 mg, 6 mol-%, 0.009 mmol), K3PO4
(96 mg, 0.45 mmol), and 1,4-dioxane (4 mL), 10d was isolated as a
1
yellow solid (64 mg, 74%); m.p. 142–144 °C. H NMR (300 MHz,
CDCl3): δ = 1.24 (t, J = 7.62 Hz, 3 H, CH3), 1.26 (t, J = 7.60 Hz,
3 H, CH3), 2.70 (q, J = 15.18, 7.59 Hz, 4 H, 2ϫCH2), 7.08–7.12
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(4-tert-butylphenyl)anthra-
quinone (11b): Starting with 8 (100 mg, 0.15 mmol), 3c (27 mg,
(m, 2 H, ArH), 7.17–7.20 (m, 2 H, ArH), 7.24–7.28 (m, 4 H, ArH), 0.15 mmol), [Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol), K3PO4
7.47 (s, 1 H, ArH), 7.60–7.63 (m, 2 H, ArH), 7.94–7.99 (m, 2 H,
ArH) ppm. 13C NMR (75.4 MHz, CDCl3): δ = 15.2, 15.3 (CH3),
28.6, 28.7 (CH2), 118.1 (q, JF,C = 320.1 Hz, CF3), 126.9, 127.0,
127.8, 127.9, 128.2, 128.5, 129.4 (CH), 131.0, 132.4, 133.7, 133.8
(48 mg, 0.225 mmol), and 1,4-dioxane (3 mL), 11b was isolated as
a yellow solid (40 mg, 41%); m.p. 80–81 °C. H NMR (300 MHz,
CDCl3): δ = 1.33 (s, 9 H, 3ϫCH3), 7.13–7.17 (m, 2 H, ArH), 7.41–
1
7.44 (m, 2 H, ArH), 7.60 (s, 1 H, ArH), 7.69–7.78 (m, 2 H, ArH),
(C), 134.0, 134.1 (CH), 135.5, 136.7, 137.8, 143.9, 144.2, 146.6, 7.99–8.02 (m, 1 H, ArH), 8.22–8.25 (m, 1 H, ArH) ppm. 13C NMR
150.1 (C), 182.8, 182.9 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ (62.9 MHz, CDCl3): δ = 30.31 (3ϫCH3), 33.75 (C), 115.0 (q, JF,C
= –74.01 (s, 3 F, CF ) ppm. IR (KBr): ν = 3024, 2962, 2932, 2874
= 319.4 Hz, CF3), 120.0 (q, JF,C = 321.7 Hz, CF3), 124.5, 126.2,
˜
3
(w), 1677 (s), 1641, 1610, 1591, 1536, 1514, 1460 (w), 1427 (s), 1410, 126.4, 126.5 (CH), 128.2 (C), 130.2 (CH), 131.0, 132.0, 132.4 (C),
1373 (w), 1320, 1311 (m), 1260 (w), 1206 (s), 1173, 1160 (w), 1133 133.5, 134.0 (CH), 135.1, 137.2, 142.1, 145.5, 150.5 (C), 180.1,
(s), 1050, 1038 (w), 1018 (m), 1005, 977 (w), 946, 899 (s), 846 (m), 180.3 (CO) ppm. 19F NMR (282 MHz, CDCl3): δ = 73.32 (q, JF
=
823, 802 (s), 766 (w), 752 (m), 729 (s), 703, 688, 663, 642 (m), 631 5.31, 2.52 Hz, 3 F, CF3), –72.56 (q, JF = 6.09, 2.97 Hz, 3 F,
(w), 599, 569 (s), 541 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 564
CF ) ppm. IR (KBr): ν = 2963 (m), 2870 (w), 1684 (s), 1594, 1577
(43) [M+], 563 (11), 537 (11), 536 (32), 535 (100), 403 (17), 402 (50), (w), 1436 (s), 1364 (w), 1325 (m), 1303 (w), 1245, 1218 (s), 1169
˜
3
401 (28), 387 (16), 386 (11), 374 (25), 373 (86). HRMS (EI, 70 eV):
(w), 1135 (s), 1105, 1045, 1018, 1000, 906 (w), 870 (m), 839 (w),
806 (m), 783, 763, 727, 703, 685, 655, 644, 624 (w), 598 (m), 575
calcd. for C31H23F3O5S [M]+ 564.12128; found 564.121848.
Eur. J. Org. Chem. 2011, 2075–2087
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2085

P. Langer et al.
FULL PAPER
(w) cm–1. GC-MS (EI, 70 eV): m/z (%) = 636 (53) [M+], 623 (12), 129.8 (d, J = 5.1 Hz), 129.9, 130.3, 131.0 (C), 131.9, 132.0, 133.9,
622 (27), 621 (90), 581 (14), 580 (27), 579 (100), 447 (26). HRMS 134.2 (CH), 138.0, 138.8, 142.4, 143.3 (C), 179.8, 179.9 (CO) ppm.
(EI, 70 eV): calcd. for C26H18F6O8S2 [M]+ 636.03418; found 19F NMR (282 MHz, CDCl3): δ = –73.25 (q, JF = 5.78, 2.84 Hz, 3
636.033895.
F, CF3), –72.48 (q, JF = 5.16, 2.25 Hz, 3 F, CF3), –62.59 (s, 3 F,
CF ) ppm. IR (KBr): ν = 2954, 2923, 2852 (w), 1690 (m), 1676 (s),
˜
3
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(4-methylphenyl)anthra-
quinone (11c): Starting with 8 (100 mg, 0.15 mmol), 3e (20 mg,
0.15 mmol), [Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol), K3PO4
(48 mg, 0.225 mmol), and 1,4-dioxane (3 mL), 11c was isolated as
1612, 1593, 1578, 1570, 1489 (w), 1446, 1429 (s), 1412 (m), 1389,
1334 (w), 1306, 1242, 1208, 1180, 1163, 1118, 1049, 1071, 1046,
1007 (s), 927, 909 (w), 879, 841 (s), 828 (m), 811, 802, 782 (s), 773
(w), 759, 741, 724, 717, 701, 680 (s), 657, 650, 624 (m), 603, 591,
571 (s), 530 (m) cm–1. GC-MS (EI, 70 eV): m/z (%) = 647 (17) [M+],
579 (10), 516 (15), 515 (49), 451 (29), 424 (25), 423 (100), 395 (13),
384 (26), 383 (50), 312 (12), 355 (37), 354 (71). HRMS (EI, 70 eV):
calcd. for C23H9F9O8S2 [M]+ 647.95896; found 647.958459.
1
a yellow solid (56 mg, 61%); m.p. 79–80 °C. H NMR (300 MHz,
CDCl3): δ = 2.37 (s, 3 H, CH3), 7.09–7.11 (m, 2 H, ArH), 7.20–
7.23 (m, 2 H, ArH), 7.58 (s, 1 H, ArH), 7.67–7.76 (m, 2 H, ArH),
7.97–8.00 (m, 1 H, ArH), 8.20–8.23 (m, 1 H, ArH) ppm. 13C NMR
(62.9 MHz, CDCl3): δ = 21.36 (CH3), 113.4 (q, JF,C = 318.8 Hz,
CF3), 123.6 (q, JF,C = 319.1 Hz, CF3), 127.2, 127.4, 127.6 (CH),
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(3-chlorophenyl)anthra-
128.3 (C), 129.3, 131.1 (CH), 132.0, 132.9, 133.4 (C), 134.6, 135.0 quinone (11f): Starting with 8 (100 mg, 0.15 mmol), 3m (23 mg,
(CH), 136.2, 138.3, 138.4, 143.1, 146.5 (C), 181.1, 181.3 (CO) ppm. 0.15 mmol), [Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol), K3PO4
19F NMR (282 MHz, CDCl3): δ = –73.33 (q, JF = 5.13, 2.34 Hz, 3
(48 mg, 0.225 mmol), and 1,4-dioxane (3 mL), 11f was isolated as
yellow crystals (53 mg, 56%); m.p. 78–80 °C. H NMR (300 MHz,
1
F, CF3), –72.58 (d, JF = 2.88 Hz, 3 F, CF ) ppm. IR (KBr): ν =
˜
3
3070, 3027, 2924, 2871 (w), 1680 (s), 1593, 1578, 1513 (w), 1432
(s), 1322 (m), 1303 (w), 1243 (m), 1203 (s), 1168 (m), 1126 (s), 1044,
1021, 1015 (w), 998 (m), 946, 905 (w), 865, 818, 805 (s), 783, 760
(m), 723 (s), 708, 684, 645, 627 (w), 593, 576 (s), 532 (w) cm–1. GC-
CDCl3): δ = 6.58 (dt, J = 7.17, 1.65 Hz, 1 H, ArH), 6.68–6.70 (m,
1 H, ArH), 6.81–6.90 (m, 2 H, ArH), 7.06 (s, 1 H, ArH), 7.19–
7.28 (m, 2 H, ArH), 7.47–7.50 (m, 1 H, ArH), 7.71–7.74 (m, 1 H,
ArH) ppm. 13C NMR (62.9 MHz, CDCl3): δ = 114.0 (q, JF,C
=
MS (EI, 70 eV): m/z (%) = 594 (17) [M + H+], 579 (14), 461 (19), 316.2 Hz, CF3), 120.0 (q, JF,C = 320.2 Hz, CF3), 124.8, 126.3,
369 (10), 330 (19), 329 (32), 316 (10), 315 (45), 301 (19), 300 (31),
126.5, 126.6, 127.5 (CH), 128.3 (C), 128.8, 129.8 (CH), 130.9,
215 (31), 64 (100), 48 (58). HRMS (EI, 70 eV): calcd. for 131.9, 132.0 (C), 133.5 (CH), 133.8 (C), 134.1 (CH), 137.8, 139.8,
C23H12F6O8S2 [M]+ 593.98723; found 593.985244.
142.2, 143.5 (C), 179.8, 179.9 (CO) ppm. 19F NMR (282 MHz,
CDCl3): δ = –73.90 (q, JF = 4.99, 2.85 Hz, 3 F, CF3), –73.11 (q,
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(4-ethylphenyl)anthraquinone
(11d): Starting with 8 (100 mg, 0.15 mmol), 3f (22 mg, 0.15 mmol),
[Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol), K3PO4 (48 mg,
0.225 mmol), and 1,4-dioxane (3 mL), 11d was isolated as an
JF,C = 5.53, 2.99 Hz, 3 F, CF ) ppm. IR (KBr): ν = 3070, 2961 (w),
˜
3
1680 (s), 1592, 1577 (w), 1433 (s), 1323 (m), 1303 (w), 1244, 1205
(s), 1169 (m), 1127, 1093, 1080 (s), 1045 (m), 1008, 876, 837, 799,
784, 761, 711, 689, 654 (s), 623 (m), 593, 572 (s), 535 (m) cm–1.
GC-MS (EI, 70 eV): m/z (%) = 617 (2ϫ37Cl, 07) [M+], 616 (37Cl,
32) [M + H+], 615 (37Cl, 24) [M+], 614 (35Cl, 82) [M + H+], 613
(35Cl, 16) [M+], 579 (15), 483 (12), 482 (12), 481 (29), 446 (16), 382
(18), 355 (18), 354 (100), 350 (12), 349 (20). HRMS (EI, 70 eV):
calcd. for C22H9ClF6O8S2 ([M]+, 35Cl) 613.93261; found
613.932573. HRMS (EI, 70 eV): calcd. for C22H9ClF6O8S2 ([M]+,
37Cl) 615.92966; found 615.931303.
1
orange solid (61 mg, 65%); m.p. 101–103 °C. H NMR (300 MHz,
CDCl3): δ = 1.25 (t, J = 7.65 Hz, CH3), 2.69 (q, J = 14.94, 7.62 Hz,
2 H, CH2), 7.12–7.15 (m, 2 H, ArH), 7.24–7.26 (m, 2 H, ArH),
7.59 (s, 1 H, ArH), 7.68–7.77 (m, 2 H, ArH), 7.98–8.01 (m, 1 H,
ArH), 8.21–8.24 (m, 1 H, ArH) ppm. 13C NMR (75.4 MHz,
CDCl3): δ = 15.2 (CH3), 28.6 (CH2), 113.2 (q, JF,C = 321.0 Hz,
CF3), 121.7 (q, JF,C = 321.0 Hz, CF3), 126.2, 126.4, 126.7, 127.0
(CH), 128.2, 130.1 (C), 131.0 (CH), 131.9, 132.4 (C), 133.5, 134.0
(CH), 135.4, 137.3, 142.1, 143.6, 145.5 (C), 180.1, 180.3 (CO) ppm. General Synthesis of 1,4-Bis(4-tert-butylphenyl)-2-(4-chlorophenyl)-
19F NMR (282 MHz, CDCl3): δ = –73.32 (q, JF = 5.31, 2.76 Hz, 3
F, CF3), –72.56 (q, JC,F = 6.09, 2.94 Hz, 3 F, CF3) ppm. IR (KBr):
anthraquinone (12): The reaction was carried out in a pressure tube.
To a suspension of 8 (100 mg, 0.15 mmol), Ar1B(OH)2 (0.3 mmol),
ν = 3075, 3027, 2965, 2931, 2874 (w), 1681 (s), 1611, 1593, 1577, and [Pd(PPh3)4] (6 mol-%) in dioxane (4 mL), was added K3PO4
˜
1512 (w), 1433 (s), 1323 (m), 1303 (w), 1243 (m), 1205 (s), 1168
(96 mg, 0.45 mmol), and the resultant solution was degassed by
(m), 1128 (s), 1044 (w), 1015, 998 (m), 905 (w), 865 (s), 826 (m), bubbling argon through the solution for 10 min. The mixture was
803 (s), 783, 760, 754 (m), 723 (s), 684, 654, 645, 626 (w), 594 (s),
533 (w). GC-MS (EI, 70 eV): m/z (%) = 608 (32) [M+], 581 (11),
580 (20), 579 (85), 475 (14), 447 (14), 383 (12), 382 (12), 354 (25),
heated at 95 °C under an argon atmosphere for 10 h, then the mix-
ture was cooled to 20 °C. Ar2B(OH)2 (0.15 mmol), [Pd(PPh3)4]
(3 mol-%), K3PO4 (48 mg, 0.225 mmol), and dioxane (2 mL) were
344 (13), 343 (23), 316 (18), 315 (100), 314 (36), 313 (14) cm–1. added and the reaction mixture was heated under an argon atmo-
HRMS (EI, 70 eV): calcd. for C24H14F6O8S2 [M]+ 608.00288;
found 608.003921.
sphere for 10 h at 110 °C. The mixture was diluted with H2O and
extracted with CH2Cl2 (3ϫ25 mL). The combined organic layers
were dried (Na2SO4), filtered, and the filtrate was concentrated in
vacuo. The residue was purified by flash chromatography (flash
silica gel, EtOAc/heptanes).
1,2-Bis[(trifluoromethyl)sulfonyloxy]-4-(3-trifluoromethylphenyl)-
anthraquinone (11e): Starting with 8 (100 mg, 0.15 mmol), 3g
(28 mg, 0.15 mmol), [Pd(PPh3)4] (5 mg, 3 mol-%, 0.0045 mmol),
K3PO4 (48 mg, 0.225 mmol), and 1,4-dioxane (3 mL), 11e was iso-
Compound 12a: Starting with 8 (100 mg, 0.15 mmol), 3c (54 mg,
0.3 mmol), [Pd(PPh3)4] (17 mg, 10 mol-%, 0.015 mmol), K3PO4
1
lated as yellow crystals (40 mg, 40%); m.p. 169–171 °C. H NMR
(300 MHz, CDCl3): δ = 7.41 (d, J = 7.71 Hz, 1 H, ArH), 7.47 (b, (143 mg, 0.675 mmol), 1,4-dioxane (5 mL), and 3d (23 mg,
1 H, ArH), 7.54 (d, J = 7.80 Hz 1 H, ArH), 7.59 (s, 1 H, ArH), 0.15 mmol), 12a was isolated as a yellow solid (40 mg, 45%); m.p.
7.68–7.71 (m, 1 H, ArH), 7.73–7.81 (m, 2 H, ArH), 7.97–8.00 (m,
288–290 °C. 1H NMR (300 MHz, CDCl3): δ = 1.25 (s, 9 H,
1 H, ArH), 8.23–8.26 (m, 1 H, ArH) ppm. 13C NMR (62.9 MHz, 3ϫCH3), 1.32 (s, 9 H, 3ϫCH3), 6.80–6.83 (m, 2 H, ArH), 6.84–
CDCl3): δ = 117.5 (q, JF,C = 321.3 Hz, CF3), 121.2 (q, JF,C
=
6.88 (m, 2 H, ArH), 6.98–7.01 (m, 2 H, ArH), 7.17–7.24 (m, 4 H,
ArH), 7.39–7.41 (m, 2 H, ArH), 7.48 (s, 1 H, ArH), 7.58–7.62 (m,
272.3 Hz, CF3), 123.5 (d, J = 3.8 Hz), 124.2 (d, J = 3.7 Hz), 126.3,
126.6 (CH), 127.3 (q, JF,C = 265.5 Hz, CF3), 128.0 (CH), 128.4 (C), 2 H, ArH), 7.94–8.01 (m, 2 H, ArH) ppm. 13C NMR (62.9 MHz,
2086
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2075–2087

Site-Selective Arylation of Alizarin and Purpurin
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CDCl3): δ = 31.3, 31.4 (6ϫCH3), 34.5, 34.6 (C), 124.7, 125.1,
126.6, 126.8, 127.6, 127.8 (CH), 128.2 (C), 128.9, 130.7 (CH),
131.8, 133.1 (C), 133.5, 133.6 (CH), 133.9, 134.4, 136.5, 138.2 (C),
138.6 (CH), 139.0, 141.7, 143.8, 146.5, 149.5, 150.0 (C), 183.9,
184.5 (CO) ppm. IR (KBr): ν = 3076, 3025 (w), 2958 (m), 2902,
˜
2865 (w), 1677 (s), 1591 (m), 1523, 1512, 1490, 1471, 1462, 1443,
1423, 1400, 1358 (w), 1329, 1306, 1269, 1248, 1217 (m), 1158, 1137,
1115 (w), 1092 (m), 1039 (w), 1013 (m), 964, 946, 935, 915, 899,
863, 846, 836 (w), 822 (s), 800 (m), 768, 746 (w), 730 (s), 721 (m),
697, 669, 658, 647, 631, 621, 608 (w), 575, 568 (m), 531 (w) cm–1.
GC-MS (EI, 70 eV): m/z (%) = 585 (37Cl, 08) [M + H+], 584 (37Cl,
22) [M+], 583 (35Cl, 22) [M + H+], 582 (35Cl, 46) [M+], 581 (10),
570 (15), 569 (30), 568 (40), 567 (63), 566 (10), 565 (10), 528 (20),
527 (44), 526 (56), 525 (100), 524 (11), 513 (10), 512 (23), 511 (27),
510 (43). HRMS (EI, 70 eV): calcd. for C40H35ClO2 [M]+
582.23201; found 582.231833.
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Acknowledgments
Financial support by the Deutscher Akademischer Austauschdienst
(DAAD) (PhD fellowship to A. M.) is gratefully acknowledged.
The authors are grateful to Dr. Dirk Michalik for his valuable sup-
port with regard to the 2D NMR experiments.
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Received: November 7, 2010
Published Online: March 1, 2011
Eur. J. Org. Chem. 2011, 2075–2087
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2087