Suzuki-Miyaura reactions of the bis(triflates) of 1,3- and 1,4-dihydroxythioxanthone. Electronic and steric effects on the site-selectivity

Article abstract of DOI:10.1016/j.tet.2011.10.095

The palladium(0)-catalyzed Suzuki cross-coupling reactions of the bis(triflates) of 1,3- and 1,4-dihydroxythioxanthone afforded various aryl-substituted thioxanthones. While the Suzuki reactions of the bis(triflate) derived from 1,3-dihydroxythioxanthone proceeded by site-selective attack in favor of position 3, the reactions of the bis(triflate) of 1,4- dihydroxythioxanthone proceeded in favor of position 1. The site-selectivity is controlled by steric and electronic parameters.

Full text of DOI:10.1016/j.tet.2011.10.095

Tetrahedron 68 (2012) 711e721
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
SuzukieMiyaura reactions of the bis(triflates) of 1,3- and
1,4-dihydroxythioxanthone. Electronic and steric effects on the site-selectivity
,b,
Dhafer Saber Zinad a, Holger Feist a, Alexander Villinger a, Peter Langer a
*
a
€
€
Institut fur Chemie, Universitat Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany
b
€
€
Leibniz-Institut fur Katalyse e. V. an der Universitat Rostock, Albert-Einstein-Str. 29a, 18059 Rostock, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 August 2011
Received in revised form 13 October 2011
Accepted 27 October 2011
Available online 2 November 2011
The palladium(0)-catalyzed Suzuki cross-coupling reactions of the bis(triflates) of 1,3- and 1,4-
dihydroxythioxanthone afforded various aryl-substituted thioxanthones. While the Suzuki reactions of
the bis(triflate) derived from 1,3-dihydroxythioxanthone proceeded by site-selective attack in favor of
position 3, the reactions of the bis(triflate) of 1,4-dihydroxythioxanthone proceeded in favor of position 1.
The site-selectivity is controlled by steric and electronic parameters.
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Catalysis
Thioxanthones
Palladium
SuzukieMiyaura reaction
Regioselectivity
1. Introduction
of 1,3-dihydroxythioxanthone.7 Herein, we report full details of this
work and an extension of the preparative scope. In addition, we
Thioxanthones are present in various pharmacologically active
natural products. For example, lucanthone and hycanthone have
been reported to be active against murine pancreatic adenocarci-
noma.1 A number of plants, such as Cartoxylum cochinchinense
(Lour.), contain thioxanthone-derived natural products and have
been used as traditional medicines. Synthetic thioxanthones also
exhibit a wide range of pharmacological activities including anti-
tumor and antibiotic activity.2 Thioxanthone-derived sulfones are
known to be active against various tumors and inhibit monoamine
oxidase activity (MAO).3 In the field of material sciences, thio-
xanthones are used as activators in the photopolymerization of
acrylates and as stabilizers of polyolefins.4
report, for the first time, SuzukieMiyaura reactions of the bis(tri-
flate) of 1,4-dihydroxythioxanthone. Interestingly, the Suzuki re-
actions of the bis(triflates) of 1,3- and 1,4-dihydroxythioxanthone
proceed with different site-selectivities, which can be explained by
a combination of steric and electronic reasons.
2. 1,3-Dihydroxythioxanthone
Bis(triflate)
2
was prepared by reaction of 1,3-
dihydroxythioxanthone (1), prepared from thiosalicylic acid,8
with triflic anhydride (Scheme 1).
Classic syntheses of thioxanthones include the reaction of 2-
chlorobenzoates with thiophenols and the reaction of thio-
salicylic acids with benzene derivatives and subsequent intra-
molecular FriedeleCrafts acylation.2 Despite their utility, these
methods have several drawbacks, such as low yields or low regio-
selectivities. In recent years, site-selective SuzukieMiyaura re-
actions of polyhalides5 and polytriflates6 have been extensively
studied. Recently, we have reported the synthesis of arylated thi-
oxanthones based on SuzukieMiyaura reactions of the bis(triflate)
O
OH
O
OTf
i
S
OH
S
OTf
2
1
Scheme 1. Synthesis of 2. Reagents and conditions: (i) CH2Cl2, 1 (1.0 equiv), Et3N
(4.0 equiv), Tf2O (2.4 equiv), ꢀ78 ꢁC/20 ꢁC, 8 h.
The SuzukieMiyaura reaction of 2 with 2.4 equiv of arylboronic
acids 3aeg gave the 1,3-diarylthioxanthones 4aeg (Scheme 2,
Table 1). Good yields were obtained both for reactions of electron
rich and poor arylboronic acids. The best yields were obtained
* Corresponding author. Fax: þ49 381 4986412; e-mail address: peter.langer@
uni-rostock.de (P. Langer).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.10.095

712
D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
Table 3
O
Ar
O
S
OTf
ArB(OH)2
Optimization of the synthesis of 5a and 5f (all reactions were carried out at 60 ꢁC for
8 h)
3a-g
Entry
Basea
Solventb
Catalystc
5ad (%)
5fd (%)
i
S
Ar
OTf
1
2
3
4
5
6
7
8
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4
K3PO4
K3PO4
K3PO4
Dioxane
THF
Dioxane
THF
Dioxane
THF
Dioxane
THF
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)4]
35
41
46
41
55
66
63
87
24
32
37
33
47
50
57
78
2
4a-g
Scheme 2. Synthesis of 4aeg. Reagents and conditions: (i)
2
(1.0 equiv), 3aeg
[Pd(PPh3)4]
(2.4 equiv), Pd(PPh3)4 (10 mol %), K3PO4 (3.0 equiv), 1,4-dioxane, 90 ꢁC, 8 h.
[Pd(PPh3)2Cl2]
[Pd(PPh3)2Cl2]
[Pd(PPh3)4]
Table 1
Synthesis of 4aeg
[Pd(PPh3)4]
a
b
c
3,4
Ar
4a (%)
1.5 equiv per 0.197 mmol of 2.
5 mL per 0.197 mmol of 2.
5 mol % per 0.197 mmol of 2.
Yields of isolated products.
a
b
c
d
e
f
2-(MeO)C6H4
4-EtC6H4
4-t-BuC6H4
3,5-Me2C6H3
4-MeC6H4
4-ClC6H4
90
81
86
77
84
70
75
d
bis-arylated products. The employment of potassium phosphate
gave better yields than the use of an aqueous solution of potassium
carbonate. The use of Pd(PPh3)4 gave higher yields than the use of
[Pd(PPh3)2Cl2]. In addition, it proved to be important to use exactly
1.1 equiv of the arylboronic acids. While the use of 1,4-dioxane as
the solvent gave the best results in case of the synthesis of 1,3-
diarylthioxanthones 4, it was observed that employment of THF
was advantageous in case of monoarylated products 5. The diary-
lated products 6aec have been synthesized in two steps. Products
5b,c,f were isolated from the first step and reacted with the second
arylboronic acids 3a,h,k (71e82%) yields (Scheme 3, Table 2).
The structure of 5c was independently confirmed by X-ray
crystal structure analysis (Fig. 1).9
g
3-(CF3)C6H4
a
Yields of isolated products.
when the reactions were carried out using Pd(PPh3)4 as the catalyst
and K3PO4 as the base (dioxane, 90 ꢁC, 8 h).
3-Aryl-1-(trifluorosulfonyloxy)-thioxanthones 5aeh were pre-
pared by reaction of 2 with 1.1 equiv of arylboronic acids 3bed,fej
(Scheme 3, Table 2). The first attack occurs at position 3. It proved to
be important to carry out the reaction at 60 instead of 90 ꢁC in order
to induce a good site-selectivity and to avoid double attack. Good
yields were again obtained for reactions of both electron rich and
poor arylboronic acids.
O
OTf
O
OTf
Ar1B(OH)2
3b-d,f-j
Ar1
S
OTf
i
S
5a-h
2
ii
O
Ar2
Ar2B(OH)2
3a,h,k
S
Ar1
6a-c
Scheme 3. Synthesis of 5aeh and 6aec. Reagents and conditions: (i) 2 (1.0 equiv),
3bed,fej (1.1 equiv), Pd(PPh3)4 (5 mol %), K3PO4 (1.5 equiv), THF, 60 ꢁC, 8 h; (ii) 5b,c,f
(1.0 equiv), 3a,h,k (1.1 equiv), Pd(PPh3)4 (5 mol %), K3PO4 (1.5 equiv), 1,4-dioxane,
90 ꢁC, 6 h.
Fig. 1. Crystal structure of 5c.
Table 2
Synthesis of 5aeh and 6aec
The sequential addition of two different arylboronic acids to 2
allowed for the direct synthesis of 1,3-diarylthioxanthone 6d in
only one step (75% yield) (Scheme 4, Table 4). Based on our findings
related to the synthesis of monoarylated products 5, the first step of
the one-pot reaction was carried out at 60 ꢁC while the second step
was carried out at 90 ꢁC. One portion of the catalyst (5 mol %) was
added at the start of the reaction. It was not necessary to add
a second portion later on.
5
6
Ar1
5a (%)
Ar2
6a (%)
a
b
c
d
e
f
4-(MeO)C6H4
4-EtC6H4
4-t-BuC6H4
3,5-Me2C6H3
C6H5
87
84
75
82
71
78
81
80
a
b
2-(MeO)C6H4
4-(MeO)C6H4
82
79
c
4-ClC6H4
3,4-(MeO)2C6H3
71
g
h
3-(CF3)C6H4
4-FC6H4
a
Yields of isolated products.
1) Ar1B(OH)2
2) Ar2B(OH)2
O
Ar2
O
S
OTf
Products 5a and 5f were selected for optimization studies
S
Ar1
OTf
i
(Table 3). Thioxanthone 5a is derived from an electron rich aryl-
boronic acid, while 5f is derived from an electron poor arylboronic
acid. During the optimization, we have found that the best yields
were obtained when the reactions were carried out at 60 ꢁC.
Higher temperatures led to the formation of significant amounts of
2
6d
Scheme 4. Synthesis of 6d. Reagents and conditions: (i) (1)
2 (1.0 equiv), 3l
(1.1 equiv), Pd(PPh3)4 (5 mol %), K3PO4 (1.5 equiv), 1,4-dioxane, 60 ꢁC, 6 h; (2) 3h
(1.1 equiv), 90 ꢁC, 6 h.

D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
713
Table 4
Synthesis of 6d
Table 6
Optimization of the synthesis of 10e and 10d at 65ꢁC for 8 h
6
3
Ar1
Ar2
6a (%)
Entry
Basea
Solventb
Catalystc
10ed (%)
10dd (%)
d
l, h
2-MeC6H4
4-(MeO)C6H4
75
1
2
3
4
5
6
7
8
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4
K3PO4
K3PO4
K3PO4
Dioxane
THF
Dioxane
THF
Dioxane
THF
Dioxane
THF
[Pd(PPh)3Cl2]
[Pd(PPh)3Cl2]
[Pd(PPh3)4]
[Pd(PPh3)4]
[Pd(PPh)3Cl2]
[Pd(PPh)3Cl2]
[Pd(PPh3)4]
[Pd(PPh3)4]
33
44
41
42
51
56
60
81
22
39
40
33
48
50
52
84
a
Yields of isolated products.
3. 1,4-Dihydroxythioxanthone
1,4-Dihydroxythioxanthone (7) was prepared, following
a known procedure, by reaction of thiosalicylic acid with 1,4-
benzoquinone.10 Bis(triflate) 8 was prepared by reaction of 7 with
triflic anhydride (Scheme 5).
a
1.5 equiv per 0.197 mmol of 8.
5 mL per 0.197 mmol of 8.
5 mol % (scale: 0.197 mmol of 8).
Yields of isolated products.
b
c
d
O
OH
O
OTf
Table 7
Synthesis of 10aei
i
10
3
Ar
10a (%)
S
S
a
b
c
d
e
f
g
h
i
b
c
e
f
h
i
j
l
m
4-EtC6H4
4-t-BuC6H4
4-MeC6H4
4-ClC6H4
4-(MeO)C6H4
C6H5
4-FC6H4
2-MeC6H4
3-MeC6H4
90
76
87
84
81
88
82
76
79
OH
OTf
8
7
Scheme 5. One-pot synthesis of 8. Reagents and conditions: (i) CH2Cl2, 7 (1.0 equiv),
NEt3, pyridine, Tf2O (2.4 equiv), ꢀ78 ꢁC/20 ꢁC, 8 h.
The Suzuki reaction of 8 with 2.4 equiv of arylboronic acids 3
gave the 1,4-diarylthioxanthones 9aef in 80e92% yields (Scheme 6,
Table 5). The reactions were carried at the same conditions as re-
ported for the synthesis of products 4.
a
Yields of isolated products.
O
OTf
O
Ar
Compounds 10e and 10d have been used for the optimization
of the reaction conditions for the synthesis of monoarylated
thioxanthones (Table 6). The best yields were obtained when
THF was used as the solvent and Pd(PPh3)4 (5 mol %) as the
catalyst.
The structure of product 10e was unambiguously confirmed by
2D NMR experiments (Fig. 2). In the NOESY spectrum, an in-
teraction was observed between the aromatic proton 2-H and the
aromatic protons 20-H and 60-H.
ArB(OH)2
3b,c,e,h,i,j
S
i
S
OTf
Ar
9a-f
8
Scheme 6. Synthesis of 9aef. Reagents and conditions: (i) 2 (1.0 equiv), 3 (2.4 equiv),
Pd(PPh3)4 (10 mol %), K3PO4 (3.0 equiv), THF, 90 ꢁC, 8 h.
Table 5
Synthesis of 9aef
OMe
4'
9
3
Ar
9a (%)
a
b
c
d
e
f
b
c
e
h
i
4-EtC6H4
t-BuC6H4
4-MeC6H4
4-(MeO)C6H4
C6H5
80
83
84
92
91
82
5'
6'
3'
B
2'
O
S
H
H
1'
1
j
4-FC6H4
a
Yields of isolated products.
2
A
3
The reaction of 8 with 1.1 equiv of arylboronic acids 3 afforded
4
the 1-aryl-4-(trifluorosulfonyloxy)-thioxanthones 10aei (Scheme
7, Tables 6 and 7). The first attack occurred at position 1. As for
the synthesis of products 5, it proved to be important to carry out
the reaction at 65 instead of 90 ꢁC to induce a good site-selectivity.
Good yields were again obtained both for reactions of electron rich
and poor arylboronic acids.
OTf
Fig. 2. Diagnostic NOESY correlation for 10e.
The structure of 10a was independently confirmed by X-ray
crystal structure analysis (Fig. 3).9
The one-pot reaction of 8 with two different arylboronic
acids allowed for the synthesis of 1,4-diarylthioxanthones 11aed
in only one step and in very good yields (Scheme 8, Table 8).
Based on our findings related to the synthesis of monoarylated
products 5, the first step of the one-pot reaction was carried out
at 65 ꢁC, while the second step was carried out at 90 ꢁC. One
portion of the catalyst (5 mol %) was added at the start of the
reaction.
O
OTf
O
Ar
ArB(OH)2
3b,c,e,f,h,i,j,l,m
S
8
S
10a-i
i
OTf
OTf
Scheme 7. Synthesis of 10aei. Reagents and conditions: (i) 8 (1.0 equiv), 3b,c,e,f,-
h,i,j,l,m (1.1 equiv), Pd(PPh3)4 (5 mol %), K3PO4 (1.5 equiv), THF, 65 ꢁC, 8 h.

714
D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
2
sterically more hindered
electronically more deficient
directing effect of the carbonyl group
O
S
OTf
1
OTf
sterically less hindered
electronically less deficient
2
sterically more hindered
1
electronically more deficient
directing effect of the carbonyl group
O
S
OTf
2
OTf
8
electronically less deficient
Scheme 9. Possible explanation for the site-selectivity of the reactions of bis(triflates)
2 and 8.
Fig. 3. Crystal structure of 10a.
5. Experimental section
5.1. General
1) Ar1B(OH)2
2) Ar2B(OH)2
O
S
OTf
O
Ar1
Ar2
5.1.1. Synthesis
of
9-oxo-9H-thioxanthene-1,3-diyl
bis(tri-
fluoromethanesulfonate) (2). To a solution of 1 (0.34 g, 1.39 mmol)
in CH2Cl2 (20 mL) was added Et3N (0.77 mL, 5.56 mmol) at 20 ꢁC
under an argon atmosphere. After stirring for 10 min at ꢀ78 ꢁC,
Tf2O (0.56 mL, 3.34 mmol) was added. The mixture was allowed to
warm to 20 ꢁC and stirred for further 8 h. The reaction mixture was
filtered and the filtrate was concentrated in vacuo. The residue was
chromatographed without work up (flash silica gel, heptanes/
EtOAc) and 2 was isolated as a yellow solid (0.57 g, 80%). Mp
S
i
OTf
11a-d
8
Scheme 8. Synthesis of 11aed. Reagents and conditions: (i) (1) 8 (1.0 equiv), 3h,j,h,h
(1.1 equiv), Pd(PPh3)4 (5 mol %), K3PO4 (1.5 equiv), THF, 65 ꢁC, 8 h; (2) 3e,h,c,n
(1.1 equiv), 90 ꢁC, 6 h.
149e150 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼7.11(d, 1H, J¼2.37 Hz,
Table 8
Synthesis of 11aed
ArH), 7.45e7.51(m, 3H, ArH), 7.58e7.65 (m, 1H, ArH), 8.50 (dd, 1H,
J¼1.02, 8.5 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
¼ꢀ72.3, ꢀ73.2.
d
11
3
Ar1
Ar2
11a (%)
13C NMR (62.9 MHz, CDCl3):
d
¼114.7 (CH), 118.6 (q, JF,C¼321.3 Hz,
a
b
c
h,e
j,h
h,c
h,n
4-(MeO)C6H4
4-FC6H4
4-(MeO)C6H4
4-(MeO)C6H4
4-MeC6H4
4-(MeO)C6H4
4-t-BuC6H4
3-ClC6H4
90
88
84
89
CF3), 118.7 (q, JF,C¼320.9 Hz, CF3), 118.9, 125.4, 127.7 (CH), 129.9 (C),
130.3, 133.3 (CH), 134.3, 142.7, 149.9, 150.8 (C), 177.8 (CO). IR (KBr):
v¼3081, 3030, 2958, 2923, 2851, 1728 (w), 1602, 1599, 1590 (m),
1554,1465 (w),1426 (s),1399 (m),1317,1295 (w),1246 (m),1198 (s),
1150 (m), 1133, 1099 (s), 1080 (m), 1033 (w), 989, 929, 904, 884, 819,
807, 798 (m), 768 (w), 751, 714 (m), 684, 666, 655, 635 (w), 590,
569, 542, 530 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼508 ([MþH]þ,
100), 347 (28), 283 (62), 255 (19). HRMS (EI): calcd for C15H6F6O7S3
[M]þ: 507.91744; found: 507.916890.
d
a
Yields of isolated products.
4. Conclusions
The site-selectivity of palladium catalyzed reactions of pol-
yhalides or -triflates is generally controlled by steric and elec-
tronic parameters. The first attack usually occurs at the
sterically less hindered or electronically more deficient posi-
tion.11 The Suzuki reaction of the bis(triflate) 2 proceeds by
initial attack to the sterically less hindered position 3, while the
reaction of bis(triflate) 8 proceeds by initial attack at the steri-
cally more hindered position 1. This striking difference might be
explained as follows: carbon atom 1 is the most electron de-
ficient position, but it is sterically more hindered than positions
4 and 3. In addition, the carbonyl group may direct the catalyst
to the ortho position 1. In case of compound 2, the first attack
occurs at the sterically less hindered position 3. The attack to
carbon atom C-4 of thioxanthone 8 might be hindered by the
lone pairs of the sulfur atom. In addition, position 3, located
para to the carbonyl group, is expected to be more electronically
deficient than position 4. Therefore, the attack occurs at posi-
tion 1 in case of bis(triflate) 8, but at position 3 in case of
bis(triflate) 2 (Scheme 9).
5.2. General procedure for SuzukieMiyaura reactions
A THF solution (4e5 mL) of K3PO4 (1.5 equiv per cross-coupling),
Pd(PPh3)4 (5 mol % per cross-coupling), and arylboronic acid 3
(1.1 equiv per cross-coupling) was stirred at 65e90 ꢁC for 8e10 h.
After cooling to 20 ꢁC, 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), filtered,
and the filtrate was concentrated in vacuo. The residue was purified
by column chromatography (flash silica gel, heptanes/EtOAc).
5.2.1. Synthesis of 1,3-bis(2-methoxyphenyl)-9H-thioxanthen-9-one
(4a). Starting with 2 (100 mg, 0.197 mmol), 2-methoxyphenyl-
boronic acid 3a (72 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %),
K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane (5 mL), 4a was iso-
lated as a light yellow solid (75 mg, 90%); reaction temperature:
90 ꢁC for 8 h. Mp 163e165 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼3.72 (s,
The reactions reported herein provide a convenient and regio-
selective approach to a variety of arylated thioxanthones, which are
not readily available by other methods.
3H, OCH3), 3.76 (s, 3H, OCH3), 6.87 (dd, 1H, J¼0.71, 8.19 Hz, ArH),
6.93 (d, 1H, J¼8.04 Hz, ArH), 6.97e7.02 (m, 2H, ArH), 7.19e7.36 (m,
6H, ArH), 7.46 (d, 2H, J¼1.79 Hz, ArH), 7.68 (d, 1H, J¼1.77 Hz, ArH),

D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
715
8.23 (dt, 1H, J¼0.96, 8.01 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
2H, ArH), 7.66 (d, 1H, J¼1.86 Hz, ArH), 8.27 (d, 1H, J¼7.80 Hz, ArH).
13C NMR (62.9 MHz, CDCl3):
¼20.3 (CH3), 20.5 (CH3), 122.1 (CH),
d
¼55.5 (OCH3), 55.7 (OCH3), 110.3, 111.4, 120.7, 121.0, 125.3, 125.9,
d
126.1 (CH), 127.0 (C), 128.4, 129.1, 129.4, 129.8, 130.9, 131.5 (CH),
131.6 (C), 131.8 (CH), 132.7, 136.2, 137.1, 141.2, 141.5, 156.1, 156.3 (C),
181.0 (CO). IR (KBr): v¼3377, 3056, 2997, 2930, 2833, 2247 (w),
1640, 1587 (s), 1536 (w), 1492, 1460, 1434 (s), 1485 (m), 1299, 1270
(m), 1238 (s), 1178, 1157, 1117 (m), 1074, 1057, 1047 (w), 1022 (s), 963
(w), 924 (m), 906, 877, 851(w), 834 (m), 807, 785, 771 (w), 746, 736,
722 (s), 678, 666 (m), 645, 615, 574, 552 (w) cmꢀ1. GCeMS (EI,
70 eV): m/z (%)¼423 ([MꢀH]þ, 100), 394 (29), 377 (39). HRMS (EI):
calcd for C27H20O3S [M]þ: 424.11277; found: 424.11227.
124.1 (C),124.2,124.7 (CH),125.0 (C),125.1,127.6,128.3, 128.7,129.3,
130.6, 130.7 (CH), 134.9, 136.2, 137.6, 137.7, 138.0, 142.5, 142.6, 145.8
(C), 179.7 (CO). IR (KBr): v¼3269, 3004, 2914, 2854, 2729 (w), 1640
(s), 1601 (m), 1587 (s), 1540 (m), 1503, 1494, 1468 (w), 1432 (m),
1398 (w), 1382, 1373 (m), 1332, 1315 (w), 1300 (s), 1279 (m), 1245,
1204, 1185, 1168 (w), 1150 (m), 1137, 1117, 1100, 1080 (w), 1034 (m),
1011, 966, 940 (w), 912, 889, 875 (m), 842 (s), 813, 806 (m), 769 (w),
752, 744, 719 (s), 703, 697, 692, 672, 651, 643 (m), 603 (w), 591 (m),
569, 540 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼420 ([M]þ, 54), 419
([MꢀH]þ, 100), 405 (39). HRMS (ESI): calcd for C29H25OS [MþH]þ:
421.16210; found: 421.16300.
5.2.2. Synthesis of 1,3-bis(4-ethylphenyl)-9H-thioxanthen-9-one
(4b). Starting with 2 (100 mg, 0.197 mmol), 4-ethylphenylboronic
acid 3b (70 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %), K3PO4
(125 mg, 0.59 mmol), and 1,4-dioxane (5 mL), 4b was isolated as
a light yellow solid (67 mg, 81%); reaction temperature: 90 ꢁC for
5.2.5. Synthesis of 1,3-di-(p-tolyl)-9H-thioxanthen-9-one
(4e). Starting with
2 (100 mg, 0.197 mmol), 4-methylphenyl-
boronic acid 3e (64 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %),
K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane (5 mL), 4e was iso-
lated as a light yellow solid (65 mg, 84%); reaction temperature:
8 h. Mp 179e181 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼1.18 (t, 3H,
J¼7.59 Hz, CH3), 1.21 (t, 3H, J¼7.59 Hz, CH3), 2.60 (q, 2H, J¼7.59 Hz,
CH2), 2.67 (q, 2H, J¼7.59 Hz, CH2), 7.17e7.22 (m, 6H, ArH), 7.26e7.32
(m, 1H, ArH), 7.40 (d, 1H, J¼1.86 Hz, ArH), 7.40e7.46 (m, 2H, ArH),
7.50 (d, 2H, J¼8.25 Hz, ArH), 7.64 (d, 1H, J¼1.86 Hz, ArH), 8.26 (dd,
90 ꢁC for 8 h. Mp 175e177 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼2.31(s,
3H, CH3), 2.36 (s, 3H, CH3), 7.15e7.19 (m, 6H, ArH), 7.27e7.32 (m,1H,
ArH), 7.39 (d, 1H, J¼1.89 Hz, ArH), 7.44 (d, 1H, J¼1.17 Hz, ArH), 7.48
(d, 3H, J¼8.25 Hz, ArH), 7.63 (d, 1H, J¼1.89 Hz, ArH), 8.27 (dd, 1H,
1H, J¼0.75, 8.49 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
d
¼15.3
(CH3), 15.5 (CH3), 28.6 (CH2), 28.7 (CH2), 122.9, 125.2 (CH), 125.9 (C),
126.1, 127.3, 127.4, 127.9, 128.6, 129.4, 129.8 (CH), 131.6 (C), 131.8
(CH), 135.9, 136.0, 138.9, 140.9, 142.6, 143.4, 145.1, 140.8 (C), 180.7
(CO). IR (KBr): v¼3050, 3022, 2961, 2927, 2891, 2871, 2853 (w),
1644 (s),1612 (w),1588 (s),1556,1537 (w),1510 (m),1469,1455 (w),
1432 (m), 1380, 1316 (w), 1298 (s), 1286 (m), 1231, 1184, 1162 (w),
1152,1115,1074 (m), 1051 (w),1031 (m),1017, 966 (w), 924 (m), 892,
875(w), 833 (m), 821 (s), 770 (w), 749, 720 (s), 672 (m), 659, 651,
640, 615, 591, 574, 566 (w), 553 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼420 ([M]þ, 53), 419 ([MꢀH]þ, 100), 404 (11). HRMS (EI): calcd
for C29H23OS [MꢀH]þ: 419.14641; found: 419.14579.
J¼0.78, 8.61 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
¼20.2 (CH3),
d
20.4 (CH3), 121.9, 124.2 (CH), 124.9 (C), 125.1, 126.2, 126.8, 127.6,
128.2, 128.7, 128.8 (CH), 130.5 (C), 130.7 (CH), 134.7, 134.9, 135.3,
137.8, 137.9, 139.7, 142.3, 145.7 (C), 179.7 (CO). IR (KBr): v¼3044,
3022, 2952, 2919, 2857 (w), 1631 (s), 1613 (w), 1588 (s), 1556, 1537
(w), 1511 (m), 1462 (w), 1433 (m), 1415, 1380, 1316, 1192 (w), 1256
(m), 1116,1107,1075 (m), 1044 (w),1031 (m), 1017 (w), 983, 961, 945
(w), 923 (s), 888, 877, 848, 837 (w), 811, 803 (s), 787 (m), 768 (w),
757, 748 (s), 725, 717, 675 (m), 659, 649, 631, 612, 586 (w), 568, 536
(m) cmꢀ1
.
GCeMS (EI, 70 eV): m/z (%)¼392 ([M]þ, 49), 391
([MꢀH]þ, 100). HRMS (ESI): calcd for C27H21OS [MþH]þ:
393.13080; found: 393.13090.
5.2.3. Synthesis of 1,3-bis(4-(tert-butyl)phenyl)-9H-thioxanthen-9-
one (4c). Starting with 2 (100 mg, 0.197 mmol), 4-tert-butylphe-
nylboronic acid 3c (84 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol
%), K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane (5 mL), 4c was
isolated as a light yellow solid (80 mg, 86%); reaction temperature:
5.2.6. Synthesis of 1,3-bis(4-chlorophenyl)-9H-thioxanthen-9-one
(4f). Starting with
2 (100 mg, 0.197 mmol), 4-chloro phenyl-
boronic acid 3f (73 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %),
K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane (5 mL), 4f was isolated
as a light yellow solid (60 mg, 70%); reaction temperature: 90 ꢁC for
90 ꢁC for 8 h. Mp 123e125 ꢁC. 1H NMR (300 MHz, CDCl3):
d¼1.28 (s,
9H, 3CH3), 1.33 (s, 9H, 3CH3), 7.20 (d, 2H, 8.49 Hz, ArH), 7.28e7.33
(m, 1H, ArH), 7.35e7.40 (m, 3H, ArH), 7.42e7.48 (m, 4H, ArH), 7.54
(d, 2H, J¼8.6 Hz, ArH), 7.66 (d, 1H, J¼1.89 Hz, ArH), 8.27 (d, 1H,
8 h. Mp 230e231 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼7.19 (d, 2H,
J¼3.72 Hz, ArH), 7.32 (d, 2H, J¼1.86 Hz, ArH), 7.35e7.39 (m, 4H,
ArH), 7.41e7.49 (m, 2H, ArH), 7.53 (d, 2H, J¼8.46 Hz, ArH), 7.67 (d,
1H, J¼1.77 Hz, ArH), 8.27 (d, 1H, J¼7.71 Hz, ArH). 13C NMR
J¼7.80 Hz, ArH). 13C NMR (62.9 MHz, CDCl3):
¼30.3 (CH3), 30.5
d
(CH3), 33.4, 33.5 (C), 121.9, 123.8, 124.2, 124.9, 125.1 (CH), 125.6 (C),
126.0, 126.7, 128.6, 128.8 (CH), 130.6 (C), 130.7 (CH), 134.7, 134.9,
137.9, 139.5, 142.3, 145.7, 148.3, 151.0 (C), 179.7 (CO). IR (KBr):
v¼3389, 3051, 3030, 2952, 2901, 2865 (w), 1638 (s), 1611 (w), 1588
(s), 1556, 1537 (w), 1511 (m), 1475 (w), 1461, 1434 (m), 1416 (w),
1381, 1360 (m), 1317 (w), 1299 (s), 1267 (m), 1231, 1201 (w), 1157,
1109 (m), 1175, 1144, 1032, 1014, 961 (w), 924 (m), 890, 867 (w),
822, 754 (s), 746 (m), 719 (s), 697, 671, 671, 656, 646, 613 (w), 581
(s), 563, 549, 541 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼476 ([M]þ,
64), 475 ([MꢀH]þ, 100), 462 (15), 461 (46). HRMS (ESI): calcd for
C33H33OS [MþH]þ: 477.22470; found: 477.22430.
(75.5 MHz, CDCl3):
d
¼122.6, 124.3 (CH), 125.1 (C), 125.4, 127.1, 127.6,
127.9, 128.2, 128.3, 129.7 (CH), 130.2 (C), 131.1 (CH), 131.9, 134.2,
134.8, 135.9, 138.4, 140.8, 141.3, 144.6 (C), 179.4 (CO). IR (KBr):
v¼3064, 3041, 2920, 2851 (w), 1640, 1589 (s), 1537 (w), 1490 (s),
1470 (w), 1434 (m), 1414, 1397, 1375 (w), 1317, 1298 (m), 1284, 1263,
1234, 1186 (w), 1158 (m), 1107 (w), 1090 (s), 1076 (m), 1032, 1031
(w), 1012 (s), 926 (m), 892, 873, 844 (w), 832 (m), 816, 806, 747 (s),
727, 713 (m), 693 (w), 680, 651 (m), 643, 626, 602 (w), 567, 553 (m)
cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼433 ([MþH]þ, 44), 432 ([M]þ,
27), 431 ([MꢀH]þ, 56), 199 (100), 181 (49), 165 (16). HRMS (EI):
calcd for C25H14Cl2OS [M]þ: 432.01369; found: 432.01221.
5.2.4. Synthesis of 1,3-bis(3,5-dimethylphenyl)-9H-thioxanthen-9-
5.2.7. Synthesis
of
1,3-bis(3-(trifluoromethyl)phenyl)-9H-thio-
one (4d). Starting with
2
(100 mg, 0.197 mmol), 3,5-
xanthen-9-one (4g). Starting with 2 (100 mg, 0.197 mmol), 3-(tri-
fluoromethyl)phenylboronic acid 3g (89 mg, 0.47 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane
(5 mL), 4g was isolated as a light yellow solid (74 mg, 75%); re-
action temperature: 90 ꢁC for 8 h. Mp 167e169 ꢁC. 1H NMR
dimethylphenylboronic acid 3d (71 mg, 0.47 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane
(5 mL), 4d was isolated as a light yellow solid (64 mg, 77%); re-
action temperature: 90 ꢁC for 8 h. Mp 159e161 ꢁC. 1H NMR
(300 MHz, CDCl3):
s, 2H, ArH), 6.98 (d, 2H, J¼6.39 Hz, ArH), 7.22 (br s, 2H, ArH),
7.30e7.36 (m, 1H, ArH), 7.40 (d, 1H, J¼1.83 Hz, ArH), 7.48e7.49 (m,
d
¼2.31 (s, 6H, 2CH3), 2.32 (s, 6H, 2CH3), 6.88 (br
(300 MHz, CDCl3):
ArH), 7.56e7.62 (m, 1H, ArH), 7.58e7.59 (m, 1H, ArH), 7.73 (d, 1H,
J¼1.90 Hz, ArH), 7.77 (d, 1H, J¼7.68 Hz, ArH), 7.83 (br s, 1H, ArH),
d
¼7.32e7.38 (m, 2H, ArH), 7.42e7.54 (m, 6H,

716
D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
8.22e8.26 (m, 1H, ArH). 19F NMR (282.4 MHz, CDCl3):
d¼ꢀ62.6,
1:1). 1H NMR (300 MHz, CDCl3):
d
¼1.30 (s, 9H, 3CH3), 7.36 (d, 1H,
ꢀ62.3. 13C NMR (62.9 MHz, CDCl3):
d¼122.7 (q, JF,C¼3.7 Hz, CH),
J¼0.90 Hz, ArH), 7.38e7.46 (m, 3H, ArH), 7.48 (d, 3H, J¼1.77 Hz,
122.9 (q, JF,C¼272.5 Hz, CF3), 123.2 (q, JF,C¼272.5 Hz, CF3),123.2 (q,
JF,C¼3.9 Hz, CH), 123.3 (CH), 123.6 (q, JF,C¼3.9 Hz, CH), 124.4 (CH),
124.5 (q, JF,C¼3.9 Hz, CH), 125.4 (C), 125.6, 127.2, 128.0, 128.6, 128.7
(CH),129.5 (q, JF,C¼32.2 Hz, CeCF3), 129.7 (CH), 130.1 (C),130.3 (CH),
130.9 (q, JF,C¼32.5 Hz, CeCF3), 131.2 (CH), 134.7, 138.3, 138.7, 141.2,
142.9, 144.4 (C), 179.3 (CO). IR (KBr): v¼3270, 3063, 2959, 2852 (w),
1641 (s), 1615 (w), 1588 (s), 1547, 1496, 1486, 1462, 1455 (w), 1435
(m), 1380 (w), 1326, 1304 (s), 1268, 1251, 1226 (m), 1195 (w), 1174
(m), 1154, 1112, 1095, 1069, 1052 (s), 1033, 1000, 961, 928, 897, 887,
871, 859 (m), 797, 755 (s), 748 (m), 720, 698 (m), 686, 672, 654 (s),
627, 611, 562, 542 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼500 ([M]þ,
45), 499 ([MꢀH]þ, 100), 356 (19), 277 (07), 240 (08). HRMS (EI):
calcd for C27H13F6OS [MꢀH]þ: 499.05858; found: 499.058160.
ArH), 7.50e7.57 (m, 1H, ArH), 7.68 (d, 1H, J¼1.68 Hz, ArH), 8.52 (dd,
1H, J¼1.08, 8.10 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
d
¼ꢀ73.4. 13
C
NMR (75.5 MHz, CDCl3):
d
¼31.2 (CH3), 31.9 (C), 118.9 (q,
JF,C¼321.0 Hz, CF3), 119.5 (CH), 120.7 (C), 124.0, 125.4, 126.4, 126.9,
130.1 (CH), 130.2 (C), 132.7 (CH), 134.1, 135.3, 141.0, 145.8, 150.4,
153.2 (C), 178.6 (CO). IR (KBr): v¼3087, 3050, 3022, 2966, 2920,
2872, 2854 (w), 1630, 1602, 1589 (s), 1524 (m), 1480 (w), 1465, 1437
(m), 1424 (s), 1384 (m), 1362, 1325 (w), 1305 (m), 1278 (w), 1241
(m), 1217, 1193 (s), 1171 (m), 1131, 1105 (s), 1078, 1059, 1035, 1024,
1014 (w), 958, 903 (s), 890 (m), 829 (s), 810 (m), 801 (s), 760 (m),
753 (s), 712 (m), 666, 658, 651, 637 (w), 588 (s), 568, 537, 529 (w)
cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼493 ([MþH]þ, 17), 492 ([M]þ,
59), 478 (28), 477 (100), 316 (36). HRMS (EI): calcd for C24H19F3O4S2
[M]þ: 492.06714; found: 492.06645.
5.2.8. Synthesis of 3-(4-methoxyphenyl)-9-oxo-9H-thioxanthen-1-yl
trifluoromethanesulfonate
0.197 mmol), 4-methoxyphenylboronic
(5a). Starting
with
acid
2
3h
(100 mg,
(33 mg,
5.2.11. Synthesis of 3-(3,5-dimethylphenyl)-9-oxo-9H-thioxanthen-
1-yl trifluoromethanesulfonate (5d). Starting with 2 (100 mg,
0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol),
and THF (5 mL), 5a was isolated as a light yellow solid (80 mg, 87%);
reaction temperature: 60 ꢁC for 8 h. Mp 186e188 ꢁC. 1H NMR
0.197 mmol), 3,5-dimethylphenylboronic acid 3d (33 mg,
0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol),
and THF (5 mL), 5d was isolated as a yellow solid (75 mg, 82%); re-
action temperature: 60 ꢁC for 8 h. Mp 221e223 ꢁC. 1H NMR
(300 MHz, CDCl3):
d
¼3.81 (s, 3H, OCH3), 6.96 (d, 2H, J¼8.85 Hz,
ArH), 7.33 (d, 1H, J¼1.10 Hz, ArH), 7.41e7.58 (m, 5H, ArH), 7.64 (d,
(300 MHz, CDCl3):
d
¼2.34 (s, 6H, 2CH3), 7.04 (br s,1H, ArH), 7.14 (br s,
1H, J¼1.74 Hz, ArH), 8.53 (dd, 1H, J¼1.10, 8.2 Hz, ArH). 19F NMR
2H, ArH), 7.35 (d, 1H, J¼0.96 Hz, ArH), 7.39e7.48 (m, 2H, ArH),
(282.4 MHz, CDCl3):
d
¼ꢀ73.4. 13C NMR (75.5 MHz, CDCl3):
¼55.5
d
7.52e7.58 (m, 1H, ArH), 7.67 (d, 1H, J¼1.71 Hz, ArH), 8.53 (dd, 1H,
(OCH3), 114.9 (CH), 118.9 (q, JF,C¼321.3 Hz, CF3), 119.1 (CH), 120.3 (C),
123.4, 125.4, 126.9, 128.5 (CH), 129.2 (C), 130.1 (CH), 130.2 (C), 132.6
(CH), 135.3, 141.0, 145.4, 150.4, 161.0 (C), 178.5 (CO). IR (KBr):
v¼3082, 3063, 2841, 1651 (w), 1635, 1594 (s), 1558 (w), 1523 (m),
1471, 1460 (w), 1435 (m), 1425 (s), 1404 (w), 1389 (m), 1328, 1317,
1307 (w), 1286, 1256, 1242, 1219 (m), 1191 (s), 1135, 1126, 1111(m),
1060 (w), 1030 (m), 1007 (w), 958, 904, 889, 881 (m), 848 (w), 832
(s), 811, 799 (m), 782, 759 (w), 745 (s), 725 (w), 712, 661, 653, 637
(m), 595 (s), 582, 567, 527 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼
466 ([M]þ, 100), 334 (13), 305 (44), 262 (17). HRMS (EI): calcd for
C21H13F3O5S2 [M]þ: 466.01510; found: 466.015129.
J¼1.02, 7.68 Hz, ArH).19F NMR (282.4 MHz, CDCl3):
d
¼ꢀ73.4.13C NMR
(75.5 MHz, CDCl3):
d
¼20.4 (CH3), 117.9 (q, JF,C¼321.1 Hz, CF3), 118.7
(CH), 119.7 (C), 123.3, 124.0, 124.4, 125.9, 129.1 (CH), 129.2 (C), 130.3,
131.6 (CH), 134.3, 136.0, 138.1, 139.9, 145.2, 149.2 (C), 177.6 (CO). IR
(KBr): v¼3152, 3115, 3059, 2951, 2917, 2849 (w), 1631, 1601, 1588 (s),
1555(w),1534(m),1503,1483(w),1427(s),1408(w),1375,1302,1248
(m), 1217, 1197, 1186, 1130 (s), 1081 (m), 1031, 1004 (w), 964, 911 (m),
894, 888 (s), 871 (m), 842, 813, 803 (s), 760 (w), 727 (w), 715, 686, 660
(m), 630 (w), 609 (m), 589 (s), 568(m), 545, 537 (w) cmꢀ1. GCeMS(EI,
70 eV): m/z (%)¼464 ([M]þ,100), 303 (46), 275 (27). HRMS (EI): calcd
for C22H15F3O4S2 [M]þ: 464.03584; found: 464.03623.
5.2.9. Synthesis of 3-(4-ethylphenyl)-9-oxo-9H-thioxanthen-1-yl
5.2.12. Synthesis of 9-oxo-3-phenyl-9H-thioxanthen-1-yl tri-
fluoromethanesulfonate (5e). Starting with 2 (100 mg, 0.197 mmol),
phenylboronic acid 3i (26 mg, 0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol
%), K3PO4 (63 mg, 0.29 mmol), and THF (5 mL), 5e was isolated as
a yellow solid (61 mg, 71%); reaction temperature: 60 ꢁC for 8 h. Mp
trifluoromethanesulfonate
(5b). Starting
with
2
(100 mg,
0.197 mmol), 4-ethylphenylboronic acid 3b (32 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 5b was isolated as a yellow solid (77 mg, 84%); reaction
temperature: 60 ꢁC for 8 h. Mp 158e160 ꢁC (CH2Cl2/EtOH 1:1). 1H
163e165 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼7.36 (d, 1H, J¼0.87 Hz,
NMR (300 MHz, CDCl3):
d
¼1.21 (t, 3H, J¼7.59 Hz, CH3), 2.65 (q, 2H,
ArH), 7.39e7.47 (m, 5H, ArH), 7.50e7.56 (m, 3H, ArH), 7.67 (d, 1H,
J¼7.59 Hz, CH2), 7.27 (d, 2H, J¼8.34 Hz, ArH), 7.35 (d, 1H, J¼0.96 Hz,
ArH), 7.38e7.48 (m, 4H, ArH), 7.50e7.56 (m, 1H, ArH), 7.66 (d, 1H,
J¼1.74 Hz, ArH), 8.52 (dd, 1H, J¼1.05, 8.13 Hz, ArH). 19F NMR
J¼1.68 Hz, ArH), 8.50 (dd, 1H, J¼1.11, 8.16 Hz, ArH). 19F NMR
(282.4 MHz, CDCl3):
d
¼ꢀ73.3. 13C NMR (75.5 MHz, CDCl3):
¼118.9
d
(q, JF,C¼321.0 Hz, CF3),119.6 (CH),120.9 (C),124.3,125.4, 127.0,127.2,
129.4, 129.7, 130.0 (CH), 130.1 (C), 132.7 (CH), 135.3, 137.0, 141.1,
145.8, 150.4 (C), 178.5 (CO). IR (KBr): v¼3083, 3062, 3023, 2917,
2848 (w), 1635, 1606, 1588 (s), 1531 (m), 1506, 1463, 1448 (w), 1423
(s), 1404 (w), 1388 (m), 1345, 1321 (w), 1306 (m), 1277 (w), 1242,
1218 (m), 1189 (s), 1169, 1157 (m), 1135, 1124, 1109 (s), 1081, 1032
(m), 999 (w), 956, 902, 876 (s), 843 (w), 810, 802, 761, 748 (s), 716,
684, 673, 666 (m), 622 (w), 637 (w), 597, 585 (s), 568 (m), 530 (w)
cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼436 ([M]þ, 100), 275 (49), 247
(48), 245 (16). HRMS (ESI): calcd for C20H12F3O4S2 [MþH]þ:
437.01240; found: 437.01280.
(282.4 MHz, CDCl3):
d
¼ꢀ73.4. 13C NMR (62.9 MHz, CDCl3):
¼14.4
d
(CH3), 27.6 (CH2), 117.4 (q, JF,C¼321.1 Hz, CF3), 118.4 (CH), 120.4 (C),
122.9, 124.4, 125.9, 126.1, 127.9, 129.0 (CH), 129.1 (C), 131.6 (CH),
133.5, 134.3, 139.9, 144.8, 145.3, 149.3 (C), 177.5 (CO). IR (KBr):
v¼3052, 2960, 2929, 2871 (w), 1641, 1602, 1589 (s), 1524 (m), 1454,
1444 (w), 1422 (s), 1386, 1316, 1303, 1240 (m), 1221, 1186 (s), 1157
(w), 1134, 1123 (s), 1110 (m), 1080, 1060, 1033, 1018 (w), 955, 899 (s),
862 (w), 839 (m), 811, 798 (s), 759 (w), 745 (s), 714 (m), 666, 659,
637 (w), 595, 577, 569 (s), 531 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼464 ([M]þ, 100), 332 (14), 303 (39), 275 (17), 260 (19). HRMS
(EI): calcd for C22H15F3O4S2 [M]þ: 464.03584; found: 464.03590.
5.2.13. Synthesis of 3-(4-chlorophenyl)-9-oxo-9H-thioxanthen-1-yl
5.2.10. Synthesis of 3-(4-(tert-butyl)phenyl)-9-oxo-9H-thioxanthen-
trifluoromethanesulfonate
(5f). Starting
with
2
(100 mg,
1-yl trifluoromethanesulfonate (5c). Starting with
2
(100 mg,
0.197 mmol), 4-chlorophenylboronic acid 3f (34 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 5f was isolated as a yellow solid (72 mg, 78%); reaction
temperature: 60 ꢁC for 8 h. Mp 133e135 ꢁC. 1H NMR (300 MHz,
0.197 mmol), 4-tert-butyl phenylboronic acid 3c (39 mg,
0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol),
and THF (5 mL), 5c was isolated as a yellow solid (73 mg, 75%);
reaction temperature: 60 ꢁC for 8 h. Mp 170e172 ꢁC (CH2Cl2/EtOH
CDCl3):
d
¼7.34 (d, 1H, J¼0.80 Hz, ArH), 7.42e7.51 (m, 6H, ArH), 7.57

D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
717
(d, 1H, J¼8.25 Hz, ArH), 7.67 (d, 1H, J¼1.67 Hz, ArH), 8.45 (dd, 1H,
temperature: 90 ꢁC for 6 h. Mp 185e187 ꢁC. 1H NMR (300 MHz,
CDCl3):
J¼1.01, 7.95 Hz, ArH). 19F NMR (282.4 MHz,CDCl3):
d
¼ꢀ73.3. 13C
d
¼1.20 (t, 3H, J¼7.59 Hz, CH3), 2.63 (s, 2H, J¼7.59 Hz, CH2),
NMR (75.5 MHz, CDCl3):
d
¼118.7 (q, JF,C¼321.1 Hz, CF3), 119.5 (CH),
3.58 (s, 3H, OCH3), 6.88 (dd, 1H, J¼0.66, 8.19 Hz, ArH), 7.02 (td, 1H,
J¼1.02, 7.44 Hz, ArH), 7.23 (d, 3H, J¼7.68 Hz, ArH), 7.28e7.35 (m, 2H,
ArH), 7.42 (d, 1H, J¼1.86 Hz, ArH), 7.46e7.48 (m, 2H, ArH), 7.53 (d,
2H, J¼8.25 Hz, ArH), 7.66 (d, 1H, J¼1.86 Hz, ArH), 8.23 (dt, 1H,
121.1 (C), 124.2, 125.4, 127.1, 128.5(CH), 129.6 (C), 129.7, 130.2, 132.8
(CH), 135.2, 135.5, 136.1, 141.2, 144.5, 150.4 (C), 178.5 (CO). IR (KBr):
v¼3087, 3060, 3023, 2956, 2918, 2849 (w), 1714, 1673, 1668 (w),
1639, 1606, 1590 (s), 1531 (w), 1503 (m), 1463, 1456 (w), 1426 (s),
1380 (m), 1319 (w), 1303 (m), 1276, 1262 (w), 1242 (m), 1219, 1190
(s), 1167, 1159 (w), 1135, 1126 (s), 1112 (w), 1090 (s), 1049, 1033 (w),
1010 (m), 955 (s), 928 (w), 902, 890 (s), 845 (w), 832 (m), 811, 799
(s), 760 (m), 748 (s), 717, 712 (m), 692 (w), 666, 659, 654, 630 (m),
595, 586 (s), 567 (m), 558, 537 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼470 ([MþH]þ, 100), 338 (11), 311 (19), 310 (12), 309 (47), 281
(41), 274 (12), 245 (22). HRMS (ESI): calcd for C20H11ClF3O4S2
[MþH]þ: 470.97340; found: 470.97450.
J¼0.96, 8.10 Hz, ArH). 13C NMR (62.9 MHz, CDCl3):
¼15.5 (CH3),
d
28.6 (CH2), 55.5 (OCH3), 110.3, 120.7, 123.2, 125.3, 126.1 (CH), 127.0
(C), 127.3, 128.5, 128.9, 129.1, 129.4, 131.4, 131.5 (CH), 132.7, 136.0,
136.2, 138.0, 142.2, 143.7, 144.9, 156.0 (C), 180.9 (CO). IR (KBr):
v¼3272, 3109, 3061, 3012, 2964, 2865, 2238, 1922, 1899 (w), 1643,
1589 (s), 1538, 1514, 1494, 1461, 1452, 1435 (m), 1385 (w), 1301 (s),
1278 (m), 1241 (s), 1228, 1189, 1180 (w), 1156, 1117, 1074, 1052 (m),
1032 (w), 1020 (s), 964, 938 (w), 925 (m), 896, 871, 838 (w), 826 (s),
802(m), 769 (w), 751, 741, 719 (s), 677, 660 (m), 647, 636, 629, 623,
593, 577, 552 (w), 536 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼422
([M]þ, 4), 391 ([M]þ, 100), 376 (65). HRMS (EI): calcd for C28H22O2S
[M]þ: 422.13350; found: 422.13464.
5.2.14. Synthesis of 9-oxo-3-(3-(trifluoromethyl)phenyl)-9H-thio-
xanthen-1-yl trifluoromethanesulfonate (5g). Starting with
2
(100 mg, 0.197 mmol) 3-(trifluoromethyl)phenylboronic acid 3g
(41 mg, 0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg,
0.29 mmol), and THF (5 mL), 5g was isolated as a yellow solid
(80 mg, 81%); reaction temperature: 60 ꢁC for 8 h. Mp 176e177 ꢁC.
5.2.17. Synthesis of 3-(4-(tert-butyl)phenyl)-1-(4-methoxyphenyl)-
9H-thioxanthen-9-one (6b). Starting with 5c (73 mg, 0.148 mmol),
4-methoxyphenylboronic acid 3h (25 mg, 0.163 mmol), Pd(PPh3)4
(9 mg, 5 mol %), K3PO4 (47 mg, 0.22 mmol), and 1,4-dioxane (5 mL),
6b was isolated as a yellow solid (53 mg, 79%); reaction tempera-
ture: 90 ꢁC for 6 h. Mp 178e180 ꢁC (CH2Cl2/EtOH 1:1). 1H NMR
1H NMR (300 MHz, CDCl3):
d
¼7.35 (d,1H, J¼1.14 Hz, ArH), 7.40e7.48
(m, 2H, ArH), 7.54e7.62 (m, 2H, ArH), 7.67e7.74 (m, 3H, ArH), 7.77 (br
s, 1H, ArH), 8.52 (dd, 1H, J¼1.11, 8.16 Hz, ArH). 19F NMR (282.4 MHz,
CDCl3):
d
¼ꢀ73.3, ꢀ62.7. 13C NMR (62.9 MHz, CDCl3):
d¼118.9 (q,
(300 MHz, CDCl3):
d
¼1.28 (s, 9H, 3CH3), 3.79 (s, 3H, OCH3), 6.89 (d,
JF,C¼323.9 Hz, CF3),119.7 (CH),121.4 (C),123.7 (q, JF,C¼272.5 Hz, CF3),
124.0 (q, JF,C¼3.79 Hz, CH), 124.6, 125.4 (CH), 126.3 (q, JF,C¼3.66 Hz,
CH), 127.2, 130.0 (CH), 130.1 (C), 130.2, 130.6 (CH), 131.9 (q,
JF,C¼32.5 Hz, CeCF3), 132.9 (CH), 135.1, 137.9, 141.4, 144.2, 150.4 (C),
178.4 (CO). IR (KBr): v¼3083, 3062, 3023, 2918, 2851 (w),1630,1609,
1589 (s),1537,1502,1461 (w),1424 (s),1386 (m),1336 (s),1303,1267,
1240, 1224 (m), 1204 (s), 1166 (m), 1123 (s), 1078, 1066 (m), 1033,
1000 (w), 963 (s), 906, 877 (m), 814, 801 (s), 777 (w), 761, 750 (m),
734 (w), 717, 661 (m), 685 (s), 566, 657, 647, 633, 623 (w), 595 (s), 568
(m), 533 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼503 ([M]þ, 46), 375
(42), 311 (100), 283 (15), 242 (27), 214 (16),186 (29),158 (13). HRMS
(EI): calcd for C21H10F6O4S2 [M]þ: 503.99192; found: 503.99228.
2H, 8.70 Hz, ArH), 7.19 (d, 2H, J¼8.70 Hz, ArH), 7.29e7.34 (m, 1H,
ArH), 7.40e7.48 (m, 5H, ArH), 7.54 (d, 2H, J¼8.52 Hz, ArH), 7.65 (d,
1H, J¼1.83 Hz, ArH), 8.27 (dd, 1H, J¼0.75, 8.52 Hz, ArH). 13C NMR
(62.9 MHz, CDCl3):
d
¼31.3 (CH3), 34.7 (C), 55.2 (OCH3), 113.4, 122.9,
125.2 (CH), 125.9 (C), 126.0, 126.2, 127.0, 129.1, 129.4, 129.7 (CH),
131.6 (C), 131.7 (CH), 135.7, 135.8, 136.0, 139.0, 143.0, 146.0, 152.0,
158.6 (C), 180.9 (CO). IR (KBr): v¼3092, 3051, 3005, 2950, 2902,
2865, 2830 (w), 1642 (s), 1607 (m), 1587 (s), 1557, 1537 (w), 1507 (s),
1460, 1432 (m), 1415, 1379, 1359, 1316 (w), 1297 (s), 1279 (m), 1238
(s), 1176 (m), 1163 (w), 1152, 1111, 1074, 1028 (m), 1015, 961 (w), 923
(m), 891, 867 (w), 818 (s), 769 (w), 754 (s), 730, 722 (m), 709 (w),
675 (m), 653, 633, 611 (w), 573, 542 (m) cmꢀ1. GCeMS (EI, 70 eV):
m/z (%)¼450 ([M]þ, 77), 449 ([MꢀH]þ, 100). HRMS (ESI, 70 eV):
calcd for C30H27O2S [MþH]þ: 451.17260; found: 451.17250.
5.2.15. Synthesis of 3-(4-fluorophenyl)-9-oxo-9H-thioxanthen-1-yl
trifluoromethanesulfonate
(5h). Starting with
2
(100 mg,
0.197 mmol), 4-flourophenylboronic acid 3j (30 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 5h was isolated as a yellow solid (71 mg, 80%); reaction
temperature: 60 ꢁC for 8 h. Mp 179e181 ꢁC. 1H NMR (300 MHz,
5.2.18. Synthesis of 3-(4-chlorophenyl)-1-(3,4-dimethoxyphenyl)-
9H-thioxanthen-9-one (6c). Starting with 5f (72 mg, 0.153 mmol),
3,4-dimethoxyphenylboronic acid 3k (31 mg, 0.168 mmol),
Pd(PPh3)4 (9 mg, 5 mol %), K3PO4 (49 mg, 0.23 mmol), and 1,4-
dioxane (5 mL), 6c was isolated as a yellow solid (50 mg, 71%);
reaction temperature: 90 ꢁC for 6 h. Mp 168e170 ꢁC. 1H NMR
CDCl3):
d
¼7.13 (t, 2H, J¼8.52 Hz, ArH), 7.30 (d, 1H, J¼1.02 Hz, ArH),
7.38e7.45 (m, 2H, ArH), 7.49e7.58 (m, 3H, ArH), 7.63 (d, 1H,
J¼1.74 Hz, ArH), 8.50 (dd, 1H, J¼0.90, 7.80 Hz, ArH). 19F NMR
(300 MHz, CDCl3):
d
¼3.79 (s, 3H, OCH3), 3.87 (s, 3H, OCH3), 6.77 (d,
(282.4 MHz, CDCl3):
d
¼ꢀ111.1, ꢀ73.3. 13C NMR (75.5 MHz, CDCl3):
1H, J¼1.86 Hz, ArH), 6.81 (dd, 1H, J¼1.92, 8.16 Hz, ArH), 6.88 (d, 1H,
J¼8.16 Hz, ArH), 7.32e7.39 (m, 4H, ArH), 7.48e7.55 (m, 4H, ArH),
7.62 (d, 1H, J¼1.9 Hz, ArH), 8.25 (dd, 1H, J¼0.84, 8.70 Hz, ArH). 13C
d¼116.5 (d, JF,C¼21.9 Hz, CH),118.9 (q, JF,C¼321.2 Hz, CF3),119.5 (CH),
120.9 (C), 124.1, 125.4, 127.0 (CH), 129.1 (d, JF,C¼8.46 Hz, CH), 130.1,
132.8 (CH), 133.1, 133.2, 135.2, 141.2, 144.7, 150.4 (C), 163.8 (d,
JF,C¼250.9 Hz, CeF), 178.8 (CO). IR (KBr): v¼3070, 2953, 2921, 2851
(w), 1637(m), 1591 (s), 1531 (w), 1514 (m), 1488, 1435 (w), 1421 (s),
1383 (m), 1321 (w), 1302 (m), 1281 (w),1241(m),1207,1191 (s), 1163
(m), 1137, 1116 (s), 1079 (m), 1034, 1014, 993 (w), 957, 903 (s), 876
(m), 854 (w), 838, 810, 792, 754, 741 (s), 715, 665, 659 (m), 636 (w),
590 (s), 569 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼454 ([M]þ, 100),
294 (10), 293 (49), 265 (52), 263 (14). HRMS (ESI): calcd for
C20H11F4O4S2 [MþH]þ: 455.00290; found: 455.00300.
NMR (62.9 MHz, CDCl3):
d¼54.8, 54.9 (OCH3), 109.7, 110.7, 119.1,
122.0, 124.3, 125.4, 127.6, 128.1, 128.3, 128.6 (CH), 130.7 (C), 130.9
(CH), 134.0, 134.7, 134.8, 136.1, 138.1, 141.1, 145.5, 147.2, 147.5 (C),
179.8 (CO). IR (KBr): v¼3052, 2989, 2957, 2925, 2850, 2829, 2247
(w), 1643 (s), 1609 (w), 1589 (m), 1537(w), 1513, 1491, 1469, 1462,
1454, 1434, 1417 (m), 1401, 1372, 1331 (w), 1296 (m), 1281 (w), 1257,
1240, 1216, 1185, 1170, 1153, 1136, 1122, 1102, 1092, 1077, 1056 (m),
1027, 1013 (s), 952, 932 (w), 909, 894, 875, 863 (m), 841 (w), 825
(m), 816 (s), 804, 789, 761 (m), 747, 721 (s), 683, 662, 652, 646, 629,
618, 600, 583, 541 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼458
([M]þ, 100), 457 ([MꢀH]þ, 74), 443 (24), 371 (17), 214 (14). HRMS
(EI): calcd for C27H19ClO3S [M]þ: 458.07379; found: 458.074006.
5.2.16. Synthesis of 3-(4-ethylphenyl)-1-(2-methoxyphenyl)-9H-thi-
oxanthen-9-one (6a). Starting with 5b (77 mg, 0.166 mmol), 2-
methoxyphenylboronic acid 3a (28 mg, 0.182 mmol), Pd(PPh3)4
(10 mg, 5 mol %), K3PO4 (53 mg, 0.25 mmol), and 1,4-dioxane
(5 mL), 6a was isolated as a yellow solid (57 mg, 82%); reaction
5.2.19. Synthesis
of
1-(4-methoxyphenyl)-3-(o-tolyl)-9H-thio-
xanthen-9-one (6d). Starting with 2 (100 mg, 0.197 mmol), 2-

718
D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
methylphenylboronic
acid
3l
(29 mg,
0.22 mmol),
4-
butylphenylboronic acid 3c (84 mg, 0.47 mmol), Pd(PPh3)4 (23 mg,
10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 9b was
isolated as a yellow solid (78 mg, 83%); reaction temperature: 90 ꢁC
methoxyphenylboronic acid 3h (34 mg, 0.22 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and 1,4-dioxane
(5 mL), 6d was isolated as a yellow solid (60 mg, 75%); reaction
temperature: at 60 ꢁC for 8 h, at 90 ꢁC for 6 h. Mp 168e170 ꢁC. 1H
for 8 h. Mp 108e110 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼1.33 (s, 9H,
3CH3), 1.35 (s, 9H, 3CH3), 7.20 (d, 2H, J¼10.5 Hz, ArH), 7.26 (d, 2H,
J¼9.15 Hz, ArH), 7.35e7.45 (m, 7H, ArH), 7.47 (d, 2H, J¼10.1 Hz,
ArH), 8.19 (dd,1H, J¼1.17, 9.57 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
NMR (300 MHz, CDCl3):
d
¼2.37 (s, 3H, CH3), 3.77 (s, 3H, OCH3), 6.88
(d, 2H, J¼8.73 Hz, ArH), 7.17e7.23 (m, 7H, ArH), 7.31e7.36 (m, 1H,
ArH), 7.42 (d, 1H, J¼1.74 Hz, ArH), 7.47e7.52 (m, 2H, ArH), 8.28 (dd,
d¼30.4, 30.5 (CH3), 33.5, 33.8 (C), 123.9, 124.4, 124.6, 125.0, 126.6
1H, J¼0.84, 8.64 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
d¼20.4
(CH), 127.1 (C), 128.1, 128.2, 128.9 (CH), 130.2 (C), 130.6, 131.0 (CH),
134.6, 135.4, 136.4, 137.6, 139.4, 143.7, 148.2, 150.5 (C), 181.2 (CO). IR
(KBr): v¼3025, 2959, 2902, 2866, 2712, 2257, 1909, 1726 (w), 1638
(s), 1614 (w), 1589 (m), 1563, 1543 (w), 1509, 1461 (m), 1433 (s),
1392, 1360 (w), 1308 (m), 1289 (w), 1267, 1256 (m), 1237 (w), 1212,
1203 (m), 1168, 1161, 1138 (w), 1112 (m), 1105, 1080, 1047, 1025 (w),
1014 (m), 973, 961, 935 (w), 917, 905, 847 (m), 835 (w), 821 (s), 801,
759, 748 (m), 724 (s), 700, 687, 666 (w), 648 (m), 625, 611, 604, 590
(w), 568 (s) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼477 ([MþH]þ, 28),
476 ([M]þ, 81), 475 ([MꢀH]þ, 100), 461 (51), 419 (14). HRMS (EI):
calcd for C33H31OS [MꢀH]þ: 475.20901; found: 475.20877.
(CH3), 55.2 (OCH3), 113.4, 125.2, 125.4 (CH), 125.9 (C), 126.1, 126.3,
128.3, 129.2, 129.5, 129.7, 130.7 (CH), 131.7 (C), 131.8, 131.9 (CH),
135.3, 135.5, 135.9, 138.4, 139.6, 144.8, 145.6, 158.6 (C), 181.2 (CO). IR
(KBr): v¼3399, 3057, 2950, 2928, 2861, 2834 (w), 1641 (s), 1607 (m),
1588 (s), 1536(w), 1508 (s), 1489, 1461 (w), 1435 (m), 1409, 1384,
1316 (w), 1295 (m), 1241 (s), 1175, 1156 (m), 1115, 1077, 1053 (w),
1032 (m), 962 (w), 923 (m), 879, 894(w), 826 (s), 808, 786, 769 (w),
755, 723 (s), 680, 667 (m), 643, 613 (w), 573 (m), 556, 536 (w) cmꢀ1
.
GCeMS (EI, 70 eV): m/z (%)¼408 ([M]þ, 70), 407 ([MꢀH]þ, 100).
HRMS (EI): calcd for C27H20O2S [M]þ: 408.11785; found: 408.11643.
5.2.20. Synthesis
of
9-oxo-9H-thioxanthene-1,4-diyl
bis(tri-
5.2.23. Synthesis of 1,4-di-p-tolyl-9H-thioxanthen-9-one
fluoromethanesulfonate) (8). To a solution of 7 (0.40 g,1.63 mmol) in
CH2Cl2 (20 mL) was added a 1:2 mixture of Et3N and pyridine
(0.34 mL, 2.46 mmol of Et3N, and 0.40 mL, 4.10 mmol of pyridine) at
20 ꢁC underan argon atmosphere. Afterstirring for 10 min at ꢀ78 ꢁC,
Tf2O (0.66 mL, 3.91 mmol) was added. The mixture was allowed to
warm to 20 ꢁC and stirred for further 8 h. The reaction mixture was
filtered and the filtrate was concentrated in vacuo. The residue was
chromatographed without work up (flash silica gel, heptanes/EtOAc)
and 8 was isolated as a yellow solid (0.72 g, 87%). Mp 140e142 ꢁC.1H
(9c). Starting
with
8
(100 mg,
0.197 mmol),
4-
methylphenylboronic acid 3e (64 mg, 0.47 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 9c
was isolated as a yellow solid (65 mg, 84%); reaction temperature:
90 ꢁC for 8 h. Mp 160e162 ꢁC.1H NMR (300 MHz, CDCl3):
d¼2.35 (s,
3H, CH3), 2.39 (s, 3H, CH3), 7.13e7.15 (m, 3H, ArH), 7.22 (d, 2H,
J¼7.63 Hz, ArH), 7.27e7.32 (m, 5H, ArH), 7.35 (d, 2H, J¼7.63 Hz,
ArH), 7.40 (dd, 1H, J¼1.37, 6.93 Hz, ArH), 8.18 (dd, 1H, J¼1.18,
7.93 Hz, ArH). 13C NMR (75.5 MHz, CDCl3):
d
¼20.3, 20.4 (2CH3),
NMR (300 MHz, CDCl3):
d
¼7.29 (d, 1H, J¼8.91 Hz, ArH), 7.48e7.58
124.4, 125.1, 126.8 (CH), 127.1 (C), 127.7, 128.1, 128.4, 128.5, 128.7
(CH), 130.2 (C), 130.6, 130.9 (CH), 134.6, 135.2, 135.4, 136.5, 137.4,
137.7,139.6,143.8 (C),181.1 (CO). IR (KBr): v¼3271, 3027, 2961, 2914,
2859, 2726, 2253 (w), 1642 (s), 1615 (w), 1589 (s), 1574, 1557, 1494,
1547 (w), 1512 (m), 1463 (w), 1434 (s), 1378, 1358 (w), 1305 (s), 1285
(w), 1250, 1234, 1204 (m), 1183, 1159, 1139 (w), 1107 (m), 1080, 1070,
1045, 1033 (w), 1016 (m), 971, 956, 934, 917, 896, 864, 848, 838 (w),
805 (s), 773 (w), 758, 736, 728 (s), 688, 661, 650 (w), 642 (m), 627,
621, 613, 601, 585 (w), 556 (m), 544 (w), 530 (s) cmꢀ1. GCeMS (EI,
70 eV): m/z (%)¼392 ([M]þ, 56), 391 ([MꢀH]þ, 100). HRMS (EI):
calcd for C27H19OS [MꢀH]þ: 391.11511; found: 391.11509.
(m, 2H, ArH), 7.62e7.67 (m, 2H, ArH), 8.50 (dd, 1H, J¼1.41, 8.1 Hz,
ArH). 19F NMR (282.4 MHz, CDCl3):
(62.9 MHz, CDCl3):
d
¼ꢀ73.2, ꢀ73.9. 13C NMR
d¼118.5, 118.7 (q, JF,C¼317.6, 321.0 Hz, CF3), 120.9
(CH), 124.2 (C), 124.8, 126.1, 128.0 (CH), 129.5 (C), 130.2 (CH), 133.2
(C), 133.5 (CH), 135.2, 143.4, 148.7 (C), 178.0 (CO). IR (KBr): v¼3080,
2961, 2904 (w),1649, 1592 (w),1429 (m), 1412, 1388,1318, 1302 (w),
1257 (s), 1236, 1216, 1199 (m), 1078, 1010 (s), 907, 882, 850 (m), 789,
758 (s), 740 (m), 691, 673, 660, 646, 620, 607 (w), 589 (m), 569, 529
(w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼508 ([MþH]þ, 43), 375 (40),
311 (100), 311 (100), 283 (14), 242 (27). HRMS (EI): calcd for
C15H6F6O7S3 [M]þ: 507.91744; found: 507.91799.
5.2.24. Synthesis of 1,4-bis(4-methoxyphenyl)-9H-thioxanthen-9-
5.2.21. Synthesis of 1,4-bis(4-ethylphenyl)-9H-thioxanthen-9-one
(9a). Starting with 8 (100 mg, 0.197 mmol), 4-ethylphenylboronic
acid 3b (71 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %), K3PO4
(125 mg, 0.59 mmol), and THF (5 mL), 9a was isolated as a yellow
solid (66 mg, 80%); reaction temperature: 90 ꢁC for 8 h. Mp
one
(9d). Starting with
8
(100 mg, 0.197 mmol), 4-
methoxyphenylboronic acid 3h (72 mg, 0.47 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 9d
was isolated as a yellow solid (77 mg, 92%); reaction temperature:
90 ꢁC for 8 h. Mp 193e194 ꢁC. 1H NMR (300 MHz, CDCl3):
d¼3.83 (s,
130e132 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼1.25e1.31 (m, 6H, 2CH3),
3H, OCH3), 3.84 (s, 3H, OCH3), 6.89 (d, 2H, J¼8.67 Hz, ArH), 6.98 (d,
2H, J¼8.70 Hz, ArH), 7.17e7.25 (m, 3H, ArH), 7.28e7.38 (m, 5H, ArH),
7.44 (td, 1H, J¼1.41, 8.19 Hz, ArH), 8.19 (dd,1H, J¼1.02, 8.01 Hz, ArH).
2.64e2.75 (m, 4H, 2CH2), 7.02e7.17 (m, 1H, ArH), 7.21e7.32 (m, 5H,
ArH), 7.35 (d, 4H, J¼8.40 Hz, ArH), 7.40e7.48 (m, 2H, ArH),
7.50e7.78 (m, 1H, ArH), 8.19 (dd, 1H, J¼1.20, 8.19 Hz, ArH). 13C NMR
13C NMR (75.5 MHz, CDCl3):
d
¼55.2, 55.4 (2OCH3),113.5,114.0,125.5,
(75.5 MHz, CDCl3):
d¼14.2, 14.4 (2CH3), 27.6, 27.7 (2CH2), 124.5,
126.2 (CH), 128.1(C), 129.1, 129.2, 129.8 (CH), 130.8 (C), 130.9 (CH),
131.3 (C),131.7,132.1(CH),135.8,136.4,137.8,138.4,144.4,158.5,159.8
(C),182.4 (CO). IR (KBr): v¼3061, 3031, 3004, 2952, 2921, 2852, 2834,
2537, 2350, 2285, 2252, 2052, 1907 (w), 1634, 1606, 1589 (s), 1575
(m),1556,1547 (w),1509 (s),1462 (m),1432 (s),1409,1377,1358 (w),
1310, 1302, 1287 (m), 1239 (s), 1193 (m), 1174 (s), 1117 (w), 1105 (m),
1081, 1049 (w), 1026 (s), 1008, 965, 935, 927, 918, 903, 877, 864, 832
(w), 815 (s), 788, 773 (w), 759, 724 (s), 689 (w), 662, 651, 644 (m),
629, 609, 594 (w), 569 (m), 542 (s) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼425 ([MþH]þ, 51), 424 ([M]þ, 99), 423 ([MꢀH]þ, 100), 380 (11).
HRMS (EI): calcd for C27H20O3S [M]þ: 424.11277; found: 424.11145.
125.1 (CH), 125.9 (C), 126.5, 126.9, 127.1, 128.2, 128.6, 128.8 (CH),
130.2 (C), 130.6, 131.0 (CH), 134.8, 135.4, 136.5, 137.7, 139.7, 141.4,
143.7, 143.8 (C), 181.2 (CO). IR (KBr): v¼3270, 3053, 3024, 2961,
2929, 2872 (w), 1730 (m), 1642 (s), 1610 (w), 1589 (m), 1547, 1511,
1494, 1474, 1462 (w), 1433 (s), 1408, 1377, 1358 (w), 1304, 1273,
1250, 1215 (m),1184,1160, 1137, 1115 (w), 1080, 1072 (m), 1045, 1027
(w), 1013 (m), 970, 934, 886 (w), 822, 757, 734 (s), 717, 690 (m), 651
(w), 640 (m), 612, 602 (w), 534 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼420 ([M]þ, 61), 419 ([MꢀH]þ, 100), 404 (12), 391 (13). HRMS
(EI): calcd for C29H23OS [MꢀH]þ: 419.14641; found: 419.14575.
5.2.22. Synthesis of 1,4-bis(4-(tert-butyl)phenyl)-9H-thioxanthen-9-
5.2.25. Synthesis of 1,4-diphenyl-9H-thioxanthen-9-one
one (9b). Starting with
8
(100 mg, 0.197 mmol), 4-tert-
(9e). Starting with 8 (100 mg, 0.197 mmol), phenylboronic acid 3i

D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
719
(57 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %), K3PO4 (125 mg,
0.59 mmol), and THF (5 mL), 9e was isolated as a yellow solid (65 mg,
91%); reaction temperature: 90 ꢁC for 8 h. Mp 193e195 ꢁC. 1H NMR
(5 mL), 10b was isolated as a yellow solid (74 mg, 76%); reaction
temperature: 65 ꢁC for 8 h. Mp 181e183 ꢁC. 1H NMR (300 MHz,
CDCl3):
d
¼1.32 (s, 9H, 3CH3), 7.13 (d, 2H, J¼8.49 Hz, ArH), 7.27 (d,1H,
(300 MHz, CDCl3):
d
¼7.27(t, 4H, J¼7.50 Hz, ArH), 7.31e7.36 (m, 4H,
J¼8.43 Hz, ArH), 7.35e7.39 (m, 3H, ArH), 7.51e7.60 (m, 3H, ArH), 8.22
ArH), 7.38e7.47 (m, 7H, ArH), 8.18 (dd, 1H, J¼1.05, 8.04 Hz, ArH). 13C
(dd,1H, J¼0.99, 8.07 Hz, ArH). 19F NMR (282.4 MHz,CDCl3):
¼ꢀ73.1.
d
NMR (75.5 MHz, CDCl3):
d¼124.5,125.2,125.5,126.8,126.9 (CH),127.0
13C NMR (75.5 MHz, CDCl3):
d¼30.4 (3CH3), 33.6 (C), 117.6 (q,
(C), 127.6, 127.7, 128.2, 128.6, 128.7 (CH), 130.1 (C), 130.7, 130.9 (CH),
135.3,136.5,137.5,137.9,142.5,144.0 (C),180.9 (CO). IR (KBr): v¼3269,
3077, 3055, 3045, 3023, 2917, 2849 (w), 1638 (s), 1622 (m), 1589 (s),
1574 (w),1548 (m),1519,1514 (w),1491 (m),1462 (w),1441 (m),1429
(s),1358 (w),1313,1306 (s),1286,1251,1235 (m),1177 (w),1163,1115,
1076,1069,1049 (m),1033 (w),1022 (m),1001, 975, 961 (w), 934 (m),
908, 875, 717, 690, 852 (w), 838, 823 (m), 811, 767 (w), 752, 730, 692
(s), 652, 638, 619, 609, 604 (m), 548 (w), 530 (s) cmꢀ1. GCeMS (EI,
70 eV): m/z (%)¼364 ([M]þ, 50), 363 ([MꢀH]þ,100). HRMS (EI): calcd
for C25H15OS [MꢀH]þ: 363.08381; found: 363.08337.
JF,C¼320.8 Hz, CF3), 122.1, 123.9, 124.8, 126.1, 126.5 (CH), 128.2 (C),
128.6,129.3 (CH),130.1 (C),131.4 (CH),132.8,137.8,142.4,145.0,149.1
(C), 179.4 (CO). IR (KBr): v¼3106, 3071, 3027, 2959, 2903, 2865 (w),
1643 (s),1614 (w),1591,1582 (m),1507,1474,1461 (w),1419 (s),1373,
1316 (w), 1305 (m), 1283, 1263, 1247, 1238 (w), 1214 (s), 1187 (m),
1269,1160 (w),1130 (s),1115 (m),1078,1052,1035,1014 (w), 972 (m),
906 (w), 884 (s), 854 (w), 844, 821 (m), 796 (s), 765 (w), 758 (m), 747
(w), 735 (s), 720 (m), 686, 666, 653, 632 (w), 603 (s), 593 (m), 573,
564 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼492 ([M]þ, 41), 477 (13),
359 (68), 344 (23), 303 (63), 302 (100), 274 (15). HRMS (EI): calcd for
C24H19F3O4S2 [M]þ: 492.06714; found: 492.06628.
5.2.26. Synthesis of 1,4-bis(4-fluorophenyl)-9H-thioxanthen-9-one
(9f). Starting with 8 (100 mg, 0.197 mmol), 4-flourophenylboronic
acid 3j (66 mg, 0.47 mmol), Pd(PPh3)4 (23 mg, 10 mol %), K3PO4
(125 mg, 0.59 mmol), and THF (5 mL), 9f was isolated as a yellow
solid (65 mg, 82%); reaction temperature: 90 ꢁC for 8 h. Mp
5.2.29. Synthesis of 9-oxo-1-(p-tolyl)-9H-thioxanthen-4-yl tri-
fluoromethanesulfonate (10c). Starting with8 (100 mg, 0.197 mmol),
4-methylphenylboronic acid 3e (30 mg, 0.22 mmol), Pd(PPh3)4
(11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF (5 mL),10c was
isolated as a yellow solid (77 mg, 87%); reaction temperature: 65 ꢁC
186e188 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼7.04 (t, 2H, J¼8.76 Hz,
ArH), 7.14 (d, 2H, J¼8.70 Hz, ArH), 7.17e7.23 (m, 3H, ArH), 7.27e7.51
for 8 h. Mp 130e132 ꢁC. 1H NMR (300 MHz, CDCl3):
d¼2.37 (s, 3H,
(m, 6H, ArH), 8.18 (dd, 1H, J¼1.05, 8.61 Hz, ArH). 19F NMR
CH3), 7.09 (d, 2H, J¼8.1 Hz, ArH), 7.17 (d, 2H, J¼7.95 Hz, ArH), 7.25
(d,1H, J¼8.43 Hz, ArH), 7.35e7.42 (m, 1H, ArH), 7.52e7.57 (m, 3H,
ArH), 8.22 (d, 1H, J¼7.89 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
(282.4 MHz, CDCl3):
d
d
¼ꢀ115.9, ꢀ112.6. 13C NMR (75.5 MHz, CDCl3):
¼113.9 (d, JF,C¼21.5 Hz, CH), 114.8 (d, JF,C¼21.7 Hz, CH), 124.5, 125.4
(CH), 127.1 (C), 128.2 (CH), 128.4 (d, JF,C¼7.87 Hz, CH), 128.7 (CH),
129.9 (C), 130.4 (d, JF,C¼8.27 Hz, CH), 130.9, 131.0 (CH), 133.3 (d,
JF,C¼3.35 Hz, C), 135.0, 136.8, 137.1 (C), 138.3 (d, JF,C¼3.61 Hz, C),
143.1 (C), 160.7 (d, JF,C¼245.5 Hz, CeF), 161.9 (d, JF,C¼248.6 Hz, CeF),
180.8 (CO). IR (KBr): v¼3072, 3045, 2961, 2920, 2850 (w), 1639 (s),
1600 (m), 1590 (s), 1558, 1550 (w), 1506 (s), 1463 (w), 1434 (s), 1406,
1359 (w), 1307 (m), 1288, 1279, 1259 (w), 1220 (s), 1168 (w), 1157,
1090 (m), 1070, 1043, 1033 (w), 1013 (m), 961 (w), 931 (m), 866 (w),
845 (m), 823, 797 (s), 785 (m), 760, 738 (s), 688 (w), 660, 650, 641
(m), 630, 608 (w), 591 (m), 553, 533 (s) cmꢀ1. GCeMS (EI, 70 eV): m/
z (%)¼400 ([M]þ, 59), 399 ([MꢀH]þ, 100). HRMS (EI): calcd for
C25H31F2OS [MꢀH]þ: 399.06497; found: 399.06452.
d
¼ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
d¼21.37 (CH3), 118.6 (q,
JF,C¼320.7 Hz, CF3), 123.1, 125.9, 127.2, 127.7, 128.9 (CH), 129.2 (C),
129.6,130.1 (CH),131.1 (C),132.4 (CH),132.5,133.8,137.1,138.9,143.4,
146.1 (C),180.4 (CO). IR (KBr): v¼3290, 3090, 3055, 3028, 2953, 2921,
2850, 2666 (w), 1652 (s), 1614 (w), 1589, 1582 (m), 1552, 1515, 1463
(w),1436 (m),1424 (s),1407 (m),1312 (w),1301,1294,1248 (m),1206,
1190 (s),1166 (w),1157 (m),1137,1131 (s),1109 (m),1076,1050,1034,
1017 (w), 968 (m), 945, 934 (w), 883 (s), 872 (m), 851 (w), 834, 801
(s), 780 (m), 760, 732 (s), 689, 675, 649, 639 (w), 618, 601, 590 (s), 571
(m), 563, 552 (w), 533 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼450
([M]þ, 43), 317 (100), 302 (78), 274 (17). HRMS (EI): calcd for
C21H13F3O4S2 [M]þ: 450.02019; found: 450.01967.
5.2.27. Synthesis of 1-(4-ethylphenyl)-9-oxo-9H-thioxanthen-4-
5.2.30. Synthesis of 1-(4-chlorophenyl)-9-oxo-9H-thioxanthen-4-yl
yltrifluoromethanesulfonate (10a). Starting with
8
(100 mg,
trifluoromethanesulfonate (10d). Starting with
8
(100 mg,
0.197 mmol), 4-ethylphenylboronic acid 3b (32 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 10a was isolated as a yellow solid (82 mg, 90%); reaction
temperature: 65 ꢁC for 8 h. Mp 196e198 ꢁC (CH2Cl2/EtOH 1:1). 1H
0.197 mmol), 4-chlorophenylboronic acid 3f (34 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 10d was isolated as a yellow solid (78 mg, 84%); reaction
temperature: 65 ꢁC for 8 h. Mp 133e135 ꢁC. 1H NMR (300 MHz,
NMR(300 MHz, CDCl3):
d
¼1.23 (t, 3H, J¼7.6 Hz, CH3), 2.67 (q, 2H,
CDCl3):
d
¼7.12 (d, 2H, J¼8.31 Hz, ArH), 7.22 (d, 1H, J¼8.46 Hz, ArH),
J¼7.6 Hz, CH2), 7.10 (d, 2H, J¼8.20 Hz, ArH), 7.15e7.20 (m, 2H, ArH),
7.25 (d,1H, J¼8.4 Hz, ArH), 7.27e7.41 (m,1H, ArH), 7.49e7.54 (m, 3H,
ArH), 8.19 (dd, 1H, J¼0.99, 8.10 Hz, ArH). 19F NMR (282.4 MHz,
7.33 (d, 2H, J¼8.31 Hz, ArH), 7.38e7.43 (m, 1H, ArH), 7.54e7.61 (m,
3H, ArH), 8.22 (dd, 1H, J¼0.90, 8.01 Hz, ArH). 19F NMR (282.4 MHz,
CDCl3):
d
¼ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
d¼118.6 (q,
CDCl3):
d
¼ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
d¼14.2 (CH3), 27.6
JF,C¼320.8 Hz, CF3),123.3,126.0,127.3,128.4,129.1,129.7,129.9 (CH),
130.7,131.2 (C),132.7 (CH),132.9,133.4,133.8,140.4,143.8,144.7 (C),
180.1 (CO). IR (KBr): v¼3281, 3097, 3066, 2922, 2853, 2667, 2554 (w),
1649 (s), 1614 (w), 1588 (m), 1568, 1551, 1492, 1464, 1455 (w), 1424
(s), 1407, 1397 (m), 1377, 1315 (w), 1302, 1294 (m), 1277, 1247, 1238
(w), 1223, 1205, 1209, 1188 (s), 1158 (m), 1135, 1129 (s), 1090, 1077
(m),1048,1035 (w),1012, 971 (m), 881 (s), 871 (m), 847, 834 (m), 815,
805, 759 (s), 739 (w), 734 (s), 711, 686, 665 (w), 647, 631 (m), 615, 601
(s), 588 (m), 568, 555, 538 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼
470 ([MþH]þ, 38), 337 (100), 302 (68), 274 (26), 245 (14). HRMS (EI):
calcd for C20H10F3ClO4S2 [M]þ: 469.96556; found: 469.96474.
(CH2), 117.6 (q, JF,C¼318.7 Hz, CF3), 122.1, 124.8, 126.1, 126.6, 126.7
(CH), 128.2 (C), 128.6, 129.1 (CH), 130.0 (C), 131.4 (CH), 132.8, 138.1,
142.2, 142.4, 145.0, 179.3 (CO). IR (KBr): v¼3060, 3028, 2960, 2928,
2870, 2852 (w), 1644 (s), 1614 (w), 1593, 1580 (m), 1555, 1511, 1454
(w),1430 (s),1372,1316 (w),1303 (m),1274,1260 (w),1247 (m),1219,
1205,1186 (s),1160 (m),1134 (s),1114,1079,1049,1034,1017, 971 (m),
883 (s), 857, 836, 831 (m), 802, 756, 739 (s), 724 (m), 693, 666, 652
(w), 640 (s), 632 (m), 603, 590 (s), 566, 535 (w) cmꢀ1. GCeMS (EI,
70 eV): m/z (%)¼464 ([M]þ, 26), 331 (100), 302 (89), 274 (24). HRMS
(EI): calcd for C22H15F3O4S2 [M]þ: 464.03584; found: 464.03664.
5.2.28. Synthesis of 1-(4-(tert-butyl)phenyl)-9-oxo-9H-thioxanthen-
5.2.31. Synthesis of 1-(4-methoxyphenyl)-9-oxo-9H-thioxanthen-4-
4-yl trifluoromethanesulfonate (10b). Starting with
0.197 mmol), 4-tert-butylphenylboronic acid 3c (39 mg, 0.22 mmol),
8
(100 mg,
yl trifluoromethanesulfonate (10e). Starting with
0.197 mmol), 4-methoxyphenylboronic acid
8
3h
(100 mg,
(33 mg,
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
0.22 mmol), Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol),

720
D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
and THF (5 mL), 10e was isolated as a yellow solid (74 mg, 81%);
reaction temperature: 65 ꢁC for 8 h. Mp 162e164 ꢁC. 1H NMR
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 10h was isolated as a yellow solid (67 mg, 76%); reaction
temperature: 65 ꢁC for 8 h. Mp 100e102 ꢁC. 1H NMR (300 MHz,
(300 MHz, CDCl3):
d
¼3.79 (s, 3H, OCH3), 6.89 (d, 2H, J¼8.76 Hz,
ArH), 7.12 (d, 2H, J¼8.73 Hz, ArH), 7.25 (d, 1H, J¼8.40 Hz, ArH),
CDCl3):
d
¼1.95 (s, 3H, CH3), 6.97 (d, 1H, J¼7.53 Hz, ArH), 7.16e7.28
7.35e7.41 (m, 1H, ArH), 7.50e7.56 (m, 3H, ArH), 8.20 (d, 1H, 8.01 Hz,
(m, 4H, ArH), 7.33e7.39 (m, 1H, ArH), 7.54e7.58 (m, 3H, ArH), 8.22
(dd, 1H, J¼0.90, 8.10 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
ArH). 19F NMR (282.4 MHz, CDCl3):
d
¼ꢀ73.1. 13C NMR (75.5 MHz,
CDCl3):
d¼54.2 (OCH3),112.6 (CH),117.6 (q, JF,C¼320.9 Hz, CF3),122.1,
d
¼ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
d¼20.2 (CH3), 118.6 (q,
124.8, 126.1, 128.0 (CH), 128.1 (C), 128.6, 129.1 (CH), 130.1 (C), 131.4
(CH), 131.5, 132.8, 133.0, 142.3, 144.7, 158.0 (C), 179.5 (CO). IR (KBr):
v¼3290, 3104, 3071, 3034, 2996, 2950, 2934, 2907, 2853, 2833,
1682 (w), 1652 (s), 1607 (w), 1589, 1589 (m), 1567, 1552 (w), 1513
(m), 1464, 1455 (w), 1424 (s), 1375, 1353, 1314 (w), 1303, 1295 (m),
1271 (w), 1248, 1241 (m), 1224, 1202, 1191, 1178 (s), 1164, 1157 (w),
1131 (s), 1108 (m), 1078, 1055, 1035 (w), 1026, 972 (m), 885 (s), 846
(m), 832 (w), 819, 807 (s), 779 (w), 761, 734 (s), 690, 673 (w), 650,
643 (m), 619, 599, 592 (s), 574, 544 (m) cmꢀ1. GCeMS (EI, 70 eV):
m/z (%)¼466 ([M]þ, 36), 333 (100), 302 (31), 274 (10). HRMS (EI):
calcd for C21H13F3O5S2 [M]þ: 466.01510; found: 466.05129.
JF,C¼320.9 Hz, CF3), 123.4, 125.6, 126.0, 127.2, 127.3, 127.4 (CH), 129.4
(C), 129.5, 129.6, 129.8 (CH), 130.3, 132.4 (C), 132.6 (CH), 133.9, 134.6,
141.9, 143.6, 145.5 (C), 179.6 (CO). IR (KBr): v¼3292, 3063, 3018,
2953, 2922, 2857 (w), 1650 (s), 1592 (m), 1554, 1489 (w), 1425 (s),
1377 (w), 1301 (m), 1271 (w), 1261 (w), 1248 (m), 1209, 1188 (s),
1161 (m), 1133, 1118 (s), 1078, 1055, 1035 (w), 974 (m), 884 (s), 838
(m), 800 (s), 785 (w), 752, 737, 729 (s), 693, 675 (w), 650 (m), 602
(s), 568, 536 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼450 ([M]þ, 30),
435 (16), 317 (68), 302 (100), 274 (30). HRMS (EI): calcd for
C21H13F3O4S2 [M]þ: 450.02019; found: 450.02029.
5.2.35. Synthesis of 9-oxo-1-(m-tolyl)-9H-thioxanthen-4-yl tri-
fluoromethanesulfonate (10i). Starting with 8 (100 mg, 0.197 mmol),
3-methylphenylboronic acid 3m (30 mg, 0.22 mmol), Pd(PPh3)4
(11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF (5 mL),10i was
isolated as a yellow solid (70 mg, 79%); reaction temperature: 65 ꢁC
5.2.32. Synthesis of 9-oxo-1-phenyl-9H-thioxanthen-4-yl tri-
fluoromethanesulfonate
(10f). Starting
with
8
(100 mg,
0.197 mmol), phenylboronic acid 3i (27 mg, 0.22 mmol), Pd(PPh3)4
(11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF (5 mL), 10f
was isolated as a yellow solid (76 mg, 88%); reaction temperature:
65 ꢁC for 8 h. Mp 178e180 ꢁC. 1H NMR (300 MHz, CDCl3):
for 8 h. Mp 151e153 ꢁC. 1H NMR (300 MHz, CDCl3):
d
¼2.37 (s, 3H,
CH3), 6.99 (t, 2H, J¼7.47 Hz, ArH), 7.15 (d,1H, J¼7.59 Hz, ArH), 7.25 (t,
2H, J¼7.35 Hz, ArH), 7.36e7.43 (m,1H, ArH), 7.52e7.57 (m, 3H, ArH),
8.21 (dd, 1H, J¼0.87, 7.95 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
d
¼7.17e7.21 (m, 1H, ArH), 7.26 (d, 2H, J¼8.37 Hz, ArH), 7.35e7.42
(m, 4H, ArH), 7.53e7.57 (m,3H, ArH), 8.21 (dd, 1H, J¼0.90, 8.01 Hz,
ArH). 19F NMR (282.4 MHz, CDCl3):
CDCl3):
d
¼ꢀ73.1. 13C NMR (75.5 MHz,
d
¼ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
d
¼20.5 (CH3), 117.6 (q,
d
¼117.6 (q, JF,C¼318.8 Hz, CF3), 122.1, 124.9, 126.2, 126.3,
JF,C¼320.7 Hz, CF3), 122.1, 123.9, 124.9, 126.2, 126.9, 127.1, 127.4 (CH),
128.2 (C), 128.6, 129.0 (CH), 130.0 (C), 131.5 (CH), 132.8, 136.7, 140.8,
142.5,145.1 (C),179.2 (CO). IR (KBr): v¼3283, 3061, 2961, 2922, 2859,
2736, 2668, 2554 (w), 1651 (s), 1613, 1605 (w), 1589 (m), 1568, 1552,
1537, 1484, 1463 (w), 1426 (s), 1387, 1314 (w), 1300, 1292 (m), 1261
(w), 1249 (m), 1230, 1202 (s), 1183, 1167, 1158 (m), 1131 (s), 1119 (m),
1094, 1078, 1035 (w), 970 (m), 900 (w), 880 (s), 864 (w), 840, 806,
792, 774 (s), 763 (w), 751 (s), 740 (w), 727, 702 (m), 692, 679, 653 (w),
634 (m), 600 (s), 568, 551 (w) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼450
([M]þ, 33), 317 (100), 302 (37), 288 (12). HRMS (EI): calcd for
C21H13F3O4S2 [M]þ: 450.02019; found: 450.01998.
126.7, 127.1 (CH), 128.2 (C), 128.6, 129.0 (CH), 129.9 (C), 131.5 (CH),
131.6, 132.8, 140.9, 142.5, 145.0 (C), 179.2 (CO). IR (KBr): v¼3274,
3064, 2960, 1901 (w), 1667 (w), 1645 (s), 1622 (w), 1587 (m), 1552,
1493, 1461 (m), 1427 (s), 1409 (m), 1315, 1305 (w), 1292 (m), 1260,
1251 (w), 1227, 1207, 1187 (s), 1158 (m), 1129 (s), 1112, 1079, 1054,
1034, 1020, 971 (m), 912 (w), 879 (s), 861 (w), 842 (s), 821 (w), 799
(s), 768 (m), 756 (s), 738, 732, 701, 695, 680 (m), 651 (w), 637 (m),
616 (w), 598 (s), 569, 554 (w), 535 (m) cmꢀ1. GCeMS (EI, 70 eV): m/
z (%)¼436 ([M]þ, 36), 303 (100), 302 (45), 274 (38), 245 (12). HRMS
(EI): calcd for C20H11F3O4S2 [M]þ: 436.00454; found: 436.00406.
5.2.33. Synthesis of 1-(4-fluorophenyl)-9-oxo-9H-thioxanthen-4-yl
5.2.36. Synthesis
of
1-(4-methoxyphenyl)-4-(p-tolyl)-9H-thio-
trifluoromethanesulfonate (10g). Starting with
8
(100 mg,
xanthen-9-one (11a). Starting with 8 (100 mg, 0.197 mmol), 4-
methoxyphenylboronic acid 3h (33 mg, 0.22 mmol), 4-
methylphenylboronic acid 3e (29 mg, 0.22 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 11a
was isolated as a yellow solid (72 mg, 90%); reaction temperature: at
65 ꢁC for 8 h, at 90 ꢁC for 6 h. Mp 160e162 ꢁC. 1H NMR (300 MHz,
0.197 mmol), 4-flourophenylboronic acid 3j (31 mg, 0.22 mmol),
Pd(PPh3)4 (11 mg, 5 mol %), K3PO4 (63 mg, 0.29 mmol), and THF
(5 mL), 10g was isolated as a yellow solid (73 mg, 82%); reaction
temperature: 65 ꢁC for 8 h. Mp 157e159 ꢁC. 1H NMR (300 MHz,
CDCl3):
d
¼7.05 (t, 2H, J¼8.73 Hz, ArH), 7.12e7.18 (m, 2H, ArH), 7.23
(d, 1H, J¼8.37 Hz, ArH), 7.37e7.43 (m, 1H, ArH), 7.52e7.61 (m, 3H,
CDCl3):
d
¼2.39 (s, 3H, CH3), 3.79 (s, 3H, OCH3), 6.89 (d, 2H, J¼8.76 Hz,
ArH), 8.20 (dd, 1H, J¼0.90, 7.83 Hz, ArH). 19F NMR (282.4 MHz,
ArH), 7.19 (d, 2H, J¼8.76 Hz, ArH), 7.23 (d, 2H, J¼7.56 Hz, ArH),
CDCl3):
d
¼ꢀ114.9, ꢀ73.1. 13C NMR (75.5 MHz, CDCl3):
¼114.1 (d,
d
7.27e7.37 (m, 6H, ArH), 7.39e7.44 (m, 1H, ArH), 8.18 (dd, 1H, J¼1.08,
JF,C¼21.6 Hz, CH), 117.6 (q, JF,C¼320.9 Hz, CF3), 122.2, 124.9, 126.3
(CH),128.1(C),128.4(d, JF,C¼7.98 Hz, CH),128.6,129.0 (CH),129.7 (C),
131.6 (CH), 131.8, 132.8 (C), 136.7 (d, JF,C¼3.45 Hz, C), 142.7, 143.9 (C),
161.2 (d, JF,C¼245.4 Hz, CeF), 179.1 (CO). IR (KBr): v¼3068, 3044,
2957, 2917, 2848 (w), 1649 (s), 1620, 1601 (w), 1589 (m), 1567, 1551
(w), 1510 (m), 1463 (w), 1429 (s), 1408 (m), 1370, 1316, 1303, 1293,
1248 (w), 1213 (s), 1188, 1156 (m), 1129 (s), 1092, 1078, 1048, 1034,
1012 (w), 972 (m), 883 (s), 871, 843 (m), 832 (s), 815 (m), 804 (s), 791
(m), 761 (s), 741 (w), 733 (m), 690, 674 (w), 650, 639 (m), 617, 598 (s),
588, 571 (m), 563, 549 (w), 537 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z
(%)¼454 ([MþH]þ, 33), 321 (100), 292 (42), 263 (13). HRMS (EI):
calcd for C20H10F4O4S2 [M]þ: 453.99511; found: 453.99530.
8.04 Hz, ArH). 19F NMR (282.4 MHz, CDCl3):
d
¼ꢀ73.1. 13C NMR
(75.5 MHz, CDCl3):
d
¼21.44 (CH3), 55.2 (OCH3), 113.5, 125.5, 126.2
(CH), 128.1 (C), 129.1, 129.2, 129.4, 129.6, 129.8 (CH), 131.4 (C), 131.7,
132.0 (CH), 135.7, 135.8, 136.4, 137.5, 138.5, 138.6, 144.5, 158.6 (C),
182.4 (CO). IR (KBr): v¼3055, 3029, 3008, 2955, 2918, 2857, 2835 (w),
1635 (s),1606, 1591 (m),1576,1548 (w), 1512 (m),1461 (w),1434 (s),
1410, 1384, 1359 (w), 1318, 1307, 1290 (m), 1271 (w), 1254 (m), 1241
(s), 1172 (m), 1161, 1118, 1105, 1080, 1073 (w), 1149, 1026, 1019 (m),
973, 964, 935 (w), 920 (m), 902, 865, 854, 834 (w), 825 (m), 813 (s),
772 (w), 758, 731, 719 (s), 687, 660 (w), 651, 644 (m), 634, 609, 593
(w), 563 (m), 547 (w), 537 (s) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼409
([MþH]þ, 23), 408 ([M]þ, 76), 407 ([MꢀH]þ, 100). HRMS (ESI): calcd
for C27H21O2S [MþH]þ: 409.12568; found: 409.12630.
5.2.34. Synthesis of 9-oxo-1-(o-tolyl)-9H-thioxanthen-4-yl tri-
fluoromethanesulfonate
0.197 mmol), 2-methylphenylboronic acid 3l (30 mg, 0.22 mmol),
(10h). Starting
with
8
(100 mg,
5.2.37. Synthesis of 1-(4-fluorophenyl)-4-(4-methoxyphenyl)-9H-
thioxanthen-9-one (11b). Starting with 8 (100 mg, 0.197 mmol), 4-

D.S. Zinad et al. / Tetrahedron 68 (2012) 711e721
721
flourophenylboronic
acid
3j
(30 mg,
0.22 mmol),
4-
(KBr): v¼3100, 3070, 3053, 2998, 2947, 2931, 2902, 2831 (w), 1650
(s), 1633 (s), 1605 (w), 1588 (m), 1575, 1564, 1546 (w), 1510 (m),
1462, 1454 (w), 1432 (s), 1407, 1365 (w), 1307, 1299 (m), 1288 (w),
1237 (s), 1178 (m), 1165, 1155, 1121 (w), 1106, 1074, 1049, 1025 (m),
963 (w), 941 (m), 928, 898, 885, 866 (w), 841 (m), 819 (s), 783, 779
(m), 762 (s), 748 (w), 734 (s), 715, 692 (m), 665, 645, 623, 609, 583,
571 (w), 546 (m) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼429 ([MþH]þ,
55), 428 ([M]þ, 72), 427 ([MꢀH]þ, 100), 413 (10). HRMS (EI): calcd
for C26H16ClO2S [MꢀH]þ: 427.05540; found: 427.05524.
methoxyphenylboronic acid 3h (33 mg, 0.22 mmol), Pd(PPh3)4
(23 mg, 10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 11b
was isolated as a yellow solid (71 mg, 88%); reaction temperature:
at 65 ꢁC for 8 h, at 90 ꢁC for 6 h. Mp 194e196 ꢁC. 1H NMR (300 MHz,
CDCl3):
d
¼3.80 (s, 3H, OCH3), 7.05 (q, 4H, J¼8.76 Hz, ArH), 7.19e7.24
(m, 3H, ArH), 7.28e7.48 (m, 6H, ArH), 8.19 (dd, 1H, J¼1.05, 8.01 Hz,
ArH). 19F NMR (282.4 MHz, CDCl3):
CDCl3):
d
¼ꢀ116.2. 13C NMR (75.5 MHz,
d
¼54.3 (OCH3), 113.1 (CH), 113.9 (d, JF,C¼21.5 Hz, CH), 124.5,
125.2 (CH), 127.0 (C), 128.2 (CH), 128.4 (d, JF,C¼7.99 Hz, CH), 128.7
(CH), 129.6 (C), 129.8 (CH), 129.9 (C), 130.8, 131.1 (CH) 135.4, 137.1,
137.9 (C), 138.5 (d, JF,C¼3.42 Hz, C), 142.7, 158.9 (C), 160.8 (d,
JF,C¼245.4 Hz, CeF), 180.9 (CO). IR (KBr): v¼3057, 3031, 2954, 2920,
2850, 2251 (w), 1633 (s), 1601 (m), 1589 (s), 1574, 1548 (w), 1509 (s),
1461 (m), 1434 (s), 1359 (w), 1305, 1307, 1290 (m), 1245, 1219 (s),
1174, 1157 (m), 1105, 1092, 1081, 1045 (w), 1022 (s), 965, 931, 914,
896, 877, 867 (w), 844 (m), 828, 821 (s), 795 (m), 777 (w), 760, 731,
725 (s), 700, 689 (w), 662, 649, 641 (m), 628 (w), 607, 593 (m), 561,
550 (m), 535 (s) cmꢀ1. GCeMS (EI, 70 eV): m/z (%)¼413 ([MþH]þ,
23), 412 ([M]þ, 78), 411 ([MꢀH]þ, 100), 368 (14). HRMS (EI): calcd
for C26H16FO2S [MꢀH]þ: 411.08496; found: 411.08493.
Acknowledgements
Financial support by the DAAD (scholarship for D.S.Z.) is grate-
fully acknowledged.
References and notes
1. (a) Rosi, D.; Peruzzoti, G.; Dennis, E. W.; Berberian, D. A.; Freele, H.; Tullar, B.;
Archer, S. J. Med. Chem. 1967, 10, 867; (b) Perni, R. B.; Wentland, M. P.; Huang, J.
I.; Powles, R. G.; Aldous, S.; Klingbeil, K. M.; Peverly, A. D.; Robinson, R. G.;
Corbett, T. H.; Jones, J. L.; Mattes, K. C.; Rake, J. B.; Coughlin, S. A. J. Med. Chem.
1998, 41, 3645; (c) Kostakis, I.; Pouli, N.; Marakos, P.; Mikros, E.; Skaltsounis, A.;
Leonce, S.; Atassi, G.; Renard, P. Bioorg. Med. Chem. 2001, 9, 2793; (d) Koloky-
thas, G. M.; Kostakis, I.; Pouli, N.; Marakos, P.; Kletsasb, D.; Pratsinis, B. Bioorg.
Med. Chem. 2003, 11, 4591; (e) Zhao, J.; Larock, R. C. J. Org. Chem. 2007, 72, 583.
2. (a) Wentland, M. P.; Perni, R. B.; Hlavac, A. G.; Corbett, T. H.; Coughlin, S. A.;
Rake, J. B. Bioorg. Med. Chem. Lett. 1994, 4, 609; (b) Watanabe, M.; Pate, M.;
Tsukazaki, M.; Furukawa, S. Chem. Pharm. Bull. 1989, 37, 36; (c) Showalter, H. D.
H.; Angelo, M. M.; Berman, E. M. J. Med. Chem. 1988, 31, 1527; (d) Vacek, L.;
Foster, H. M. Chem. Abstr. 1979, 90, 72060a; (e) Archer, S.; Mattoccia, L. P.; Cioli,
D.; Seyed-Mozaffari, A.; Zayed, A. H. J. Med. Chem. 1988, 31, 254; (f) Laidlaw, G.
M.; Collins, J. C.; Archer, S.; Rosi, D.; Schulenberg, J. W. J. Org. Chem. 1973, 38,
1743; (g) Foster, B. J.; Wiegand, R. A.; Partricia, S. P.; LoRusso, M.; Rake, J.;
Corbett, T. H. Clin. Cancer Res. 1997, 3, 2047; (h) Horwitz, J. P.; Massova, I.;
Wiese, T. E.; Besler, B. H.; Corbett, T. H. J. Med. Chem. 1994, 37, 781; (i) Banerji,
A.; Deshpande, A. D.; Prabhu, B. R.; Pradhan, P. J. Nat. Prod. 1994, 57, 396.
3. Harfenist, M.; Heuser, D. J.; Joyner, C. T.; Batchelor, J. F.; White, H. L. J. Med.
Chem. 1996, 39, 1857.
5.2.38. Synthesis of 4-(4-(tert-butyl)phenyl)-1-(4-methoxyphenyl)-
9H-thioxanthen-9-one (11c). Starting with 8 (100 mg, 0.197 mmol),
4-methoxyphenylboronic acid 3h (33 mg, 0.22 mmol), 4-tert-
butylphenylboronic acid 3c (39 mg, 0.22 mmol), Pd(PPh3)4 (23 mg,
10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 11c was
isolated as a yellow solid (75 mg, 84%); reaction temperature: at
65 ꢁC for 8 h, at 90 ꢁC for 6 h. Mp 212e214 ꢁC. 1H NMR (300 MHz,
CDCl3):
d
¼1.35 (s, 9H, 3CH3), 3.80 (s, 3H, OCH3), 6.89 (d, 2H,
J¼8.64 Hz, ArH), 7.18 (d, 2H, J¼8.70 Hz, ArH), 7.22e7.43 (m, 7H,
ArH),7.47 (d, 2H, J¼8.31 Hz, ArH), 8.18 (dd,1H, J¼0.90, 7.89 Hz, ArH).
13C NMR (75.5 MHz, CDCl3):
d¼30.4 (CH3), 33.8 (C), 54.2 (OCH3),
112.5, 124.5, 124.6, 125.1 (CH), 127.0 (C), 128.1, 128.3, 128.8, 129.8
(CH), 130.3 (C), 130.6, 131.0 (CH), 134.5, 134.8, 135.4, 136.5, 137.6,
143.4, 150.5, 157.5 (C), 181.4 (CO). IR (KBr): v¼3059, 2997, 2959,
2931, 2903, 2866, 2834, 2248 (w), 1640, 1633 (s), 1606, 1589 (m),
1575, 1558, 1544 (w), 1510 (s), 1461 (m), 1350 (w), 1433 (s), 1410,
1360 (w), 1306 (m), 1290, 1271 (w), 1240 (s), 1174 (m), 1139 (w),
1113, 1105 (m), 1081 (w), 1049 (m), 1026, 1015 (m), 972, 935, 918,
907, 888, 863, 847, 838 (w), 817 (s), 779 (w), 759 (m), 744 (w), 729
4. Morita, H.; Mori, S.; Yamaoka, T. Bull. Chem. Soc. Jpn. 1988, 61, 191.
5. For reviews of cross-coupling reactions of polyhalogenated heterocycles, see:
€
€
(a) Schroter, S.; Stock, C.; Bach, T. Tetrahedron 2005, 61, 2245; (b) Schnurch, M.;
Flasik, R.; Khan, A. F.; Spina, M.; Mihovilovic, M. D.; Stanetty, P. Eur. J. Org. Chem.
2006, 3283.
6. For SuzukieMiyaura reactions of bis(triflates) of benzene derivatives and other
arenes, see for example: (a) Takeuchi, M.; Tuihiji, T.; Nishimura, J. J. Org. Chem.
1993, 58, 7388; (b) Sugiura, H.; Nigorikawa, Y.; Saiki, Y.; Nakamura, K.; Yama-
guchi, M. J. Am. Chem. Soc. 2004, 126, 14858; (c) Akimoto, K.; Suzuki, H.; Kondo,
Y.; Endo, K.; Akiba, U.; Aoyama, Y.; Hamada, F. Tetrahedron 2007, 63, 6887; (d)
Akimoto, K.; Kondo, Y.; Endo, K.; Yamada, M.; Aoyama, Y.; Hamada, F. Tetra-
hedron Lett. 2008, 49, 7361; (e) Hosokawa, S.; Fumiyama, H.; Fukuda, H.; Fu-
kuda, T.; Seki, M.; Tatsuta, K. Tetrahedron Lett. 2007, 48, 7305; (f) Nawaz, M.;
Farooq Ibad, M.; Obaid-Ur-Rahman, A.; Khera, R. A.; Villinger, A.; Langer, P.
Synlett 2010, 150; (g) Mahal, A.; Villinger, A.; Langer, P. Synlett 2010, 1085; (h)
Nawaz, M.; Ibad, M. F.; Abid, O.-U.-R.; Khera, R. A.; Villinger, A.; Langer, P. Synlett
2010, 150; (i) Mahal, A.; Villinger, A.; Langer, P. Synlett 2010, 1085; (j) Nawaz, M.;
Khera, R. A.; Malik, I.; Ibad, M. F.; Abid, O.-U. R.; Villinger, A.; Langer, P. Synlett
2010, 979; (k) Abid, O.-U.-R.; Ibad, M. F.; Nawaz, M.; Ali, A.; Sher, M.; Rama, N.
H.; Villinger, A.; Langer, P. Tetrahedron Lett. 2010, 51, 1541.
(s), 688 (w), 649 (m), 630, 621, 607, 594 (w), 568, 545 (m) cmꢀ1
.
GCeMS (EI, 70 eV): m/z (%)¼451 ([MþH]þ, 28), 450 ([M]þ, 91), 449
([MꢀH]þ, 100), 435 (12). HRMS (EI): calcd for C30H25O2S [MꢀH]þ:
449.15698; found: 449.15660.
5.2.39. Synthesis of 4-(3-chlorophenyl)-1-(4-methoxyphenyl)-9H-
thioxanthen-9-one (11d). Starting with 8 (100 mg, 0.197 mmol), 4-
methoxyphenylboronic acid 3h (33 mg, 0.22 mmol), 3-chlor-
ophenylboronic acid 3n (34 mg, 0.22 mmol), Pd(PPh3)4 (23 mg,
10 mol %), K3PO4 (125 mg, 0.59 mmol), and THF (5 mL), 11d was
isolated as a yellow solid (75 mg, 89%); reaction temperature: at
65 ꢁC for 8 h, at 90 ꢁC for 6 h. Mp 190e191 ꢁC. 1H NMR (300 MHz,
7. Zinad, D. S.; Hussain, M.; Akrawi, O. A.; Villinger, A.; Langer, P. Tetrahedron Lett.
2011, 52, 3451.
8. Sharghi, H.; Beni, S. Synthesis 2004, 2900.
9. CCDC-849357 and 849358 contains all crystallographic details of this publi-
cation and is available free of charge at www.ccdc.cam.ac.uk/conts/retrieving.
html or can be ordered from the following address: Cambridge Crystallographic
Data Centre, 12 Union Road, GB-Cambridge CB21EZ; Fax: (þ44)1223-336-033;
or deposit@ccdc.cam.ac.uk.
10. Loskutov, V. A.; Beregovaya, I. V. Russ. J. Org. Chem. 2009, 45, 1418.
11. For a simple guide for the prediction of the site-selectivity of palladium(0)-
catalyzed cross-coupling reactions based on the 1H NMR chemical shift
values, see: Handy, S. T.; Zhang, Y. Chem. Commun. 2006, 299.
CDCl3):
d
¼3.79 (s, 3H, OCH3), 6.88 (d, 2H, J¼8.73 Hz, ArH), 7.17 (d,
2H, J¼8.73 Hz, ArH), 7.24 (d, 1H, J¼7.62 Hz, ArH), 7.28e7.46 (m, 8H,
ArH), 8.18 (dd, 1H, J¼1.08, 8.04 Hz, ArH). 13C NMR (75.5 MHz,
CDCl3):
d
¼55.2 (OCH3), 113.6, 125.5, 126.4, 128.0 (CH), 128.2 (C),
128.7, 129.2, 129.3, 129.8, 129.9, 130.0 (CH), 131.3 (C), 131.9 (CH),
134.6, 135.5, 135.9, 137.1, 137.3, 140.3, 145.2, 158.7 (C), 182.2 (CO). IR