Regioselective arylations of α-amido sulfones with electron-rich arenes through friedel-crafts alkylations catalyzed by ferric chloride hexahydrate: Synthesis of unsymmetrical and bis-symmetrical triarylmethanes

Article abstract of DOI:10.1002/ejoc.200901186

Ferric chloride hexahydrate is a highly efficient catalyst for the regioselective arylation of α-amido sulfones. The products undergo further Friedel-Crafts alkylations with heteroaromatic or electron-rich arenes to afford unsymmetrical or bis-symmetrical

Full text of DOI:10.1002/ejoc.200901186

FULL PAPER
DOI: 10.1002/ejoc.200901186
Regioselective Arylations of α-Amido Sulfones with Electron-Rich Arenes
through Friedel–Crafts Alkylations Catalyzed by Ferric Chloride Hexahydrate:
Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
Ponnaboina Thirupathi[a] and Sung Soo Kim*[a]
Keywords: Iron / C–C coupling / α-Amido sulfones / Arenes / Heteroarenes / Triarylmethanes
Ferric chloride hexahydrate is a highly efficient catalyst for
aromatic or electron-rich arenes to afford unsymmetrical or
the regioselective arylation of α-amido sulfones. The prod- bis-symmetrical triarylmethanes.
ucts undergo further Friedel–Crafts alkylations with hetero-
are useful precursors of the N-acyliminium ions 3, which
Introduction
can further react with several nucleophiles such as allylsi-
lanes, silyl ketene acetals, trimethylsilyl cyanide, and elec-
tron-rich aromatics, leading to the formation of the corre-
sponding adducts 4.[5]
Friedel–Crafts alkylations[1] belong to the most impor-
tant C–C bond-forming reactions in organic chemistry.[2]
These reactions are usually assisted by protic acid or Lewis
acid catalysts. Recently, iron salts have attracted the atten-
tion of synthetic organic chemists, because iron is one of
the most abundant metals. Many iron salts are inexpensive
and commercially available.[3] These iron salts were found
to have promising catalytic abilities in many organic trans-
formations including Friedel–Crafts reactions.[3a,3g–3j] Frie-
del–Crafts reactions of electron-rich arenes are a well-
known process for the formation of C–C bonds from aro-
matic C–H bonds.[2] Here we would like to disclose our re-
cent discovery of FeCl3·6H2O-catalyzed Friedel–Crafts re-
actions between electron-rich arenes and α-amido sulfones.
Recently several workers have demonstrated that α-
amido sulfones 2 (Scheme 1) can be prepared from a variety
of aldehydes 1 by treatment with carbamates and sodium
sulfinates in the presence of aqueous formic acid.[4] These
In continuation of the development of useful synthetic
methodologies for C–C bond-forming reactions,[6] here we
report efficient FeCl3·6H2O-catalyzed Friedel–Crafts alk-
ylations of electron-rich arenes with α-amido sulfones. The
products undergo further Friedel–Crafts alkylations with
heteroaromatic or electron-rich arenes, giving rise to un-
symmetrical or bis-symmetrical triarylmethanes. Triaryl-
methanes display interesting properties and have received a
great deal of attention as leuco dyes,[7] photochromic
agents,[8] building blocks for generating dendrimers,[9] and
substrates for theoretical[10] and biological studies.[11] Al-
though many methods for the preparation of symmetrical
triarylmethanes are known,[12] the synthesis of unsymmetri-
cal derivatives is far less studied.[13–15] Here we describe a
broad range of FeCl3·6H2O-catalyzed Friedel–Crafts alk-
Scheme 1. General equation for Lewis-acid-catalyzed nucleophilic substitution of α-amido sulfones.
ylations that allow the selective preparation of structurally
[a] Department of Chemistry, Inha University,
Incheon 402-751, South Korea
diverse triarylmethanes through sequential reactions either
with the same electron-rich arene or with different ones
(Scheme 2).
E-mail: sungsoo@inha.ac.kr
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.200901186.
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Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
Scheme 2. Synthesis of triarylmethanes.
Table 1. Friedel–Crafts alkylations of 1,2,4-trimethoxybenzene with
[(benzyloxycarbonyl)amino](phenyl)methyl p-tolyl sulfone (8) cata-
lyzed by various catalysts.[a]
Results and Discussion
Initially we investigated the reaction behavior of [(benzyl-
oxycarbonyl)amino](phenyl)methyl p-tolyl sulfone (8) and
1,2,4-trimethoxybenzene (9). In the absence of catalyst
(Table 1, Entry 1) this did not give rise to any reaction. We
next examined the reaction behavior in the presence of
various Lewis acids such as CuCl, CuI, Fe(ClO4)3·xH2O,
Fe(acac)3, Fe(NO3)3·9H2O, FeCl3, and FeCl3·6H2O (En-
tries 2–8). With regard to the amount of the catalyst, reac-
tion time, and yield, FeCl3·6H2O (10 mol-%) was found to
be the most effective (Entry 8). The effects of various sol-
vents were also studied. CH2Cl2 was found to be the solvent
of choice in terms of yield and reaction time (Entries 8 and
12–15).
The optimized reaction conditions were used as a basis
for study of the scope of the Friedel–Crafts alkylation of
sulfone 8 with other activated arenes. The results are out-
lined in Table 2. The reasonably highly activated 1,3-di-
methoxybenzene (Entry 1) afforded a lower yield and re-
quired a longer reaction time than 1,2,3-, 1,3,5-, or 1,2,4-
trimethoxybenzene (Entries 2–4). This indicates that highly
activated benzenes are the best substrates for these Friedel–
Crafts alkylation reactions. 1,2,4-Trimethoxybenzene was
the most effective arene for Friedel–Crafts alkylation reac-
tion in relation to the other activated arenes (Table 2).
We then examined the scope of the Friedel–Crafts alk-
ylation reactions between various α-amido sulfones 13 and
1,2,4-trimethoxybenzene (9) and the results are summarized
in Table 3. The α-amido sulfones were treated with 1,2,4-
trimethoxybenzene (9) for 3.0–4.5 h to produce the corre-
sponding (1-alkyl)(1-aryl)methyl phenyl/tolyl sulfones 14 in
Entry Catalyst (mol-%)
Solvent
Reaction
time [h]
% Isolated
yield[b]
1
2
–
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH3Cl
12
12
12
3.5
10.0
8
3.5
3.5
3.5
3.5
5.5
5.0
4.0
4.0
trace
NR
NR
64
47
56
90
91
89
90
86
53
85
87
CuCl (10)
3
4
5
6
CuI (10)
Fe(ClO4)3 (10)
Fe(acac)3 (10)
Fe(NO3)3 (10)
FeCl3 (10)
7
8
9
10
11
12
13
14
FeCl3·6H2O (10)
FeCl3·6H2O (15)
FeCl3·6H2O (20)
FeCl3·6H2O (5)
FeCl3·6H2O (10)
FeCl3·6H2O (10)
FeCl3·6H2O (10)
FeCl3·6H2O (10)
CH3CN
CH3NO2
1,4-dioxane 5.0
good to excellent yields. α-Amido sulfones with electron- 15
donating groups attached to the benzene rings reacted with
1,2,4-trimethoxybenzene (9) to yield (alkyl)(aryl)methyl
phenyl/tolyl sulfones in excellent yields (Entries 2–9). The
presence of electron-withdrawing groups in the α-amido
sulfones prolonged the reaction times and reduced the
65
[a] Reaction conditions: sulfone 8 (1.0 mmol), 1,2,4-trimethoxyben-
zene (9) (1.0 mmol), solvent (2.0 mL), room temp. [b] Yield of iso-
lated product after flash column chromatography.
yields relative to those observed in the case of electron-do- the corresponding products in high yields (Entries 15–17).
nating groups (Entries 10 and 11). The p-, m-, and o-chloro Cyclohexyl and cyclohex-2-enyl α-amido sulfones afforded
α-amido sulfones gave the corresponding products in 89, 86 the corresponding (1-alkyl)(1-aryl)methyl phenyl/tolyl sul-
and 83% yields, respectively (Entries 12–14). The o-chloro fone derivatives in good yields (Entry 18 and 19). The reac-
isomer showed slight steric and electron effects that were tions of arylalkyl and acyclic aliphatic α-amido sulfones
responsible for the lower yield and longer reaction time give the corresponding (1-alkyl)(1-aryl)methyl tolyl sulfones
(Entry 14). 2-Naphthyl, 2-furyl, and 2-thiophenyl α-amido in 85% and in 77 and 75% yields, respectively (Entries 20–
sulfones reacted with 1,2,4-trimethoxybenzene (9) to afford 22).
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Table 2. FeCl3·6H2O-catalyzed Friedel–Crafts alkylations of sul-
fone 8 with electron-rich arenes.[a]
Table 3. FeCl3·6H2O-catalyzed Friedel–Crafts alkylations of 1,2,4-
trimethoxybenzene with α-amido sulfones.[a]
Entry
Arene 11
Product
Reaction
time [h]
% Isolated
yield[b]
1
2
3
4
11a
11b
11c
11d
12a
12b
12c
12d
4.5
4.0
3.5
3.5
83
86
89
91
[a] Reaction conditions: sulfone 8 (1.0 mmol), electron-rich arene
(1.0 mmol), CH2Cl2 (2.0 mL) at room temp. [b] Yield of isolated
product after flash column chromatography.
A plausible mechanism for the formation of 14 may start
from the N-acyliminium ion B (Figure 1) formed by elimi-
nation of arenesulfinic acid from the α-amido sulfone 13
through the action of the FeIII in FeCl3·6H2O. A reaction
between the strong electrophile B and 1,2,4-trimethoxy-
benzene (9) would then give the Friedel–Crafts product C.
FeIII could catalyze the elimination of carbamate from C,
leading to the formation of oxonium ion D.[16] The oxonium
ion D could then react once more with 1,2,4-trimethoxy-
benzene (9), giving rise to the bis-arene E through the re-
versible reaction. The formation of the bis-arene E was ob-
served by TLC (just above the spot for the desired product)
during the course of the reaction but had completely disap-
peared at end of the reaction. After a reaction time of 1.0 h,
E (R = 4-MePh) was isolated and characterized by NMR
analysis (see Figure 2, Exp. Section, and Supporting Infor-
mation). The oxonium ion D could then react in a second
Friedel–Crafts reaction with an arenesulfinic acid (Ar-
SO2H), leading to the formation of product 14.
[a] Reaction conditions: α-amido sulfone (1.0 mmol), 1,2,4-trimeth-
oxybenzene (1.0 mmol), and CH2Cl2 (2.0 mL) at room temp.
[b] Yield of isolated product after flash column chromatography.
The reusability of the FeCl3·6H2O catalyst was tested in
the reaction between sulfone 8 and 1,2,4-trimethoxybenzene
(9) under the same reaction conditions. The reaction mix- alkyl)(1-aryl)methyl tolyl sulfones 14 (R = Ph, Ar = 4-
ture was filtered, washed with diethyl ether (3ϫ15 mL), MeC6H4) and indole in the presence of FeCl3·6H2O af-
and used in a second run by charging with the same sub- forded the unsymmetrical triarylmethane 16a in 38% yield
strates. The catalytic system shows high efficiency of re- (Entry 1). An improvement in the reaction yield (46%) was
usability and could be recycled four times with a very little observed on changing the amount of FeCl3·6H2O to
decrease in the yield (Scheme 3).
20 mol-% (Entry 1). Similarly, 4-methoxy-, 3-methyl-4-
We studied the scope of the Friedel–Crafts alkylation re- methoxy-, 3-fluoro-, 4-methoxy-, and 3,4-dimethoxy-substi-
actions further with (1-alkyl)(1-aryl)methyl phenyl/tolyl sul- tuted (1-alkyl)(1-aryl)methyl sulfones 14 also reacted
fones 14 and the other electron-rich indole derivatives 15, smoothly with indole or 5-methoxyindole to give rise to the
giving rise to unsymmetrical triarylmethanes. The results corresponding unsymmetrical triarylmethanes in moderate
are summarized in Table 4. The reaction between the (1- yields (Entries 2–10).
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Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
Figure 1. Proposed mechanism of FeCl3·6H2O-catalyzed Friedel–Crafts alkylations of α-amido sulfones with 1,2,4-trimethoxybenzene.
1
Figure 2. H NMR of bis-arene E (R = 4-MePh).
The scope of the Friedel–Crafts alkylation reactions was of FeCl3·6H2O at room temp. The reaction mixture were
next examined (Table 5) with various (1-alkyl)(1-aryl)- stirred for 9.0 h to afford the corresponding bis-symmetrical
methyl tolyl sulfones 14 and 1,2,4-trimethoxybenzene (9). triarylmethane 17a in good yield (Entry 1). The corre-
The sulfone 14 (R = Ph) was treated with 9 in the presence sponding reactions of 4-methoxy-, 3-methyl-4-methoxy-,
Eur. J. Org. Chem. 2010, 1798–1808
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P. Thirupathi, S. S. Kim
FULL PAPER
Scheme 3. Reusability of catalyst.
Table 4. FeCl3·6H2O-catalyzed synthesis of unsymmetrical triarylmethanes.[a]
Entry
1
14
R1 in 15
Product
16
% Isolated
yield[b]
R
Ar
Ph
4-MeC6H4
H
16a
38[c] 40[d]
44[e] 46[a]
2
3
4
5
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
3-Me,
4-MeOC6H3
3-Me,
4-MeOC6H3
3-Me,
4-MeOC6H3
3-F,
4-MeC6H4
Ph
Ph
H
H
CH3O
H
16b
16b
16c
16d
51
55
60
53
4-MeC6H4
6
7
8
4-MeC6H4
Ph
CH3O
CH3O
H
16e
16e
16f
56
58
49
4-MeC6H4
4-MeOC6H3
3,4-(MeO)2C6H3
3,4-(MeO)2C6H3
9
10
4-MeC6H4
4-MeC6H4
H
CH3O
16g
16h
54
57
[a] Reaction conditions: (1-alkyl)(1-aryl)methyl phenyl/tolyl sulfones (1.0 mmol), indole derivative (1.0 mmol), and CH2Cl2 (2.0 mL) at
room temp.; the reaction time is 12 h. [b] Yield of isolated product after flash column chromatography. [c] Catalyst (10 mol-%) was used.
[d] Catalyst (15 mol-%) was used. [e] Catalyst (30 mol-%) was used.
3,4-dimethoxy-, and 3,4,5-trimethoxy-substituted tosyl sul- The oxonium ion C could react with indole derivatives 15
fones 14 proceeded to produce the corresponding bis-sym- or 1,2,4-trimethoxybenzene (9) to yield the corresponding
metrical triarylmethanes in 64, 59, 63, and 60% yields, Friedel–Crafts products 16 or 17 by elimination of arene-
respectively (Entries 2–5). The tolyl sulfones 14 (R = 4-Cl sulfinic acid (ArSO2H).
and 2-Cl) gave the corresponding products in 56 and 52%
Under similar reaction conditions the reaction between
yields, respectively (Entries 6 and 7).
[(benzyloxycarbonyl)amino](4-methoxy-3-methylphenyl)-
A likely mechanism for the formation of 16 or 17 could methyl p-tolyl sulfone (18) and 1,2,3-trimethoxybenzene
start from the oxonium ion C (Figure 3) formed by elimi- (19) afforded the product 20. Compound 20 further under-
nation of arenesulfinic acid from the tolyl sulfones 14 went Friedel–Crafts alkylation with the electron-rich indole
through the catalytic action of FeIII, by way of A and B. to form the unsymmetrical triarylmethane 21 (Scheme 4).
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Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
Table 5. FeCl3·6H2O-catalyzed synthesis of bis-symmetrical triarylmethanes.[a]
Entry
R in 14
Product
Reaction
time [h]
% Isolated
yield[b]
1
2
3
4
5
6
7
C6H5
17a
17b
17c
17d
17e
17f
17g
9.0
8.0
8.5
8.0
8.0
9.0
12.0
57
64
59
63
60
56
52
4-MeOC6H4
3-Me,4-MeOC6H3
3,4-(MeO)2C6H3
3,4,5-(MeO)3C6H2
4-ClC6H4
2-ClC6H4
[a] Reaction conditions: (1-alkyl)(1-aryl)methyl phenyl/tolyl sulfones (1.0 mmol), 1,2,4-trimethoxybenzene (1.0 mmol), and CH2Cl2
(2.0 mL) at room temp. [b] Yield of isolated product after flash column chromatography.
Figure 3. Proposed mechanism for the FeCl3·6H2O-catalyzed synthesis of unsymmetrical or bis-symmetrical triarylmethanes.
Scheme 4. Synthesis of an unsymmetrical triarylmethane from 1,2,3-trimethoxybenzene.
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P. Thirupathi, S. S. Kim
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128.6, 128.4, 124.4, 119.5, 107.3, 67.2, 61.0, 60.6, 55.9, 21.6 ppm.
HRMS-EI calcd. for C23H24O5S [M]+: 412.1344; found 412.1342.
Conclusions
We have described the action of FeCl3·6H2O as a highly
effective catalyst for Friedel–Crafts reactions between elec-
tron-rich arenes and α-amido sulfones. This catalyst shows
high efficiency in regioselective substitution reactions be-
tween α-amido sulfones and electron-rich arenes. The prod-
ucts undergo further Friedel–Crafts alkylations with het-
eroaromatic or electron-rich arenes, giving rise to unsym-
metrical or bis-symmetrical triarylmethanes. This provides
a facile and convenient route for the synthesis of unsymmet-
rical and bis-symmetrical triarylmethanes of wide structural
1
Compound 12c: White solid; m.p. 128 °C; yield 366 mg (89%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.64 (d, J = 8.4 Hz, 2 H),
7.50 (d, J = 8.5 Hz, 2 H), 7.25–7.39 (m, 3 H), 7.17 (d, J = 8.4 Hz,
2 H), 6.15 (s, 1 H), 6.06 (s, 2 H), 3.77 (s, 3 H), 3.64 (s, 6 H), 2.37
(s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 161.6, 143.3,
138.2, 134.4, 130.2, 128.8, 128.7, 127.8, 127.5, 104.3, 91.0, 67.7,
55.6, 55.2, 21.5 ppm. HRMS-EI calcd. for C23H24O5S [M]+:
412.1344; found 412.1316.
Compound 12d: Light yellow solid; m.p. 171 °C; yield 374 mg
(91%). H NMR (400 MHz, CDCl3, 25 °C): δ = 7.58 (s, 1 H), 7.57
1
diversity. The advantages of this method include: 1) high (d, J = 8.4 Hz, 2 H), 7.50 (d, J = 8.0 Hz, 2 H), 7.31–7.29 (m, 3 H),
7.14 (d, J = 8.4 Hz, 2 H), 6.23 (s, 1 H), 5.98 (s, 1 H), 3.91 (s, 3 H),
3.82 (s, 3 H), 3.51 (s, 3 H), 2.35 (s, 3 H) ppm. 13C NMR (50 MHz,
CDCl3, 25 °C): δ = 151.6, 149.8, 144.0, 143.0, 135.9, 133.5, 129.9,
128.9, 128.8, 128.5, 128.2, 113.1, 112.9, 96.8, 66.3, 56.5, 56.3, 55.9,
21.5 ppm. HRMS-EI calcd. for C23H24O5S [M]+: 412.1344; found
412.1343.
efficiency and excellent regioselectivity, 2) mild conditions,
and 3) reusability of the catalyst.
Experimental Section
Compound 14a: White solid; yield 354 mg (89%). 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 7.63 (d, J = 8.6 Hz, 2 H), 7.58–7.56
(m, 3 H), 7.48 (t, J = 8.6 Hz, 2 H), 7.37–6.29 (m, 5 H), 6.29 (s, 1
a) Regioselective Friedel–Crafts Arylation of α-Amido Sulfones with
Electron-Rich Arenes: An electron-rich arene (1 mmol) was added
under nitrogen to a stirred solution of the α-amido sulfone
(1 mmol) and FeCl3·6H2O (10 mol-%) in CH2Cl2 (2 mL). The mix-
ture was stirred at room temp. and the reaction was monitored by
TLC. After completion, the reaction mixture was filtered, and the
residue was washed with diethyl ether (3ϫ5 mL). In the recycling
experiment, the residue was used in the next run. The filtrate was
dried with anhydrous Na2SO4 and concentrated under vacuum.
The crude product was subjected to flash column chromatography
(silica gel, hexane/EtOAc 4:1 to 3:1) to afford the pure product.
H), 6.00 (s, 1 H), 3.91 (s, 3 H), 3.81 (s, 3 H), 3.47 (s, 3 H) ppm. 13
C
NMR (50 MHz, CDCl3, 25 °C): δ = 151.6, 149.9, 143.1, 138.8,
133.3, 133.1, 129.9, 128.8, 128.5, 128.3, 113.2, 112.7, 96.7, 66.2,
56.6, 56.2, 55.9 ppm.[3]
Compound 14b: White solid; m.p. 122–123 °C; yield 383 mg (90%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.57 (s, 1 H), 7.51 (d, J
= 8.4 Hz, 2 H), 7.45 (d, J = 8.0 Hz, 2 H), 7.14 (d, J = 8.0 Hz, 2
H), 7.12 (d, J = 8.4 Hz, 2 H), 6.31 (s, 1 H), 5.95 (s, 1 H), 3.91 (s,
3 H), 3.82 (s, 3 H), 3.50 (s, 3 H), 2.36 (s, 3 H), 2.31 (s, 3 H) ppm.
13C NMR (50 MHz, CDCl3, 25 °C): δ = 151.6, 149.8, 143.9, 143.1,
138.2, 136.1, 129.9, 129.3, 129.0, 128.9, 113.3, 113.2, 96.9, 66.1,
56.6, 56.4, 56.0, 21.6, 21.1 ppm. HRMS-EI calcd. for C24H26O5S
[M]+: 426.1501; found 426.1511.
b) Experimental Procedure for the Synthesis of Unsymmetrical or
Bis-Symmetrical Triarylmethanes: FeCl3·6H2O (10–20 mol-%) was
added under nitrogen to a mixture of a (1-alkyl)(1-aryl)methyl
phenyl/tolyl sulfone (1 mmol) and either 1,2,4-trimethoxybenzene
(1.1 mmol) or a heteroaromatic indole derivative in CH2Cl2 (2 mL).
The resulting solution was stirred at room temp. for 8.0–12.0 h.
The progress of the reaction was monitored by TLC. After comple-
tion of the reaction, the mixture was quenched with distilled water
(5 mL) and extracted with EtOAc (5 mL). The combined organic
portions were washed with water (5 mL) and saturated aqueous
NH4Cl (5 mL), dried with anhydrous Na2SO4, and concentrated
under vacuum. The crude product was subjected to flash column
chromatography (silica gel, hexane/EtOAc 3:1) to provide pure
product.
Compound 14c: White solid; m.p. 143.0 °C; yield 411 mg (93%). 1H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.58 (s, 1 H), 7.52–7.48 (m,
4 H), 7.14 (d, J = 8.0 Hz, 2 H), 6.84 (d, J = 8.6 Hz, 2 H), 6.32 (s,
1 H), 5.93 (s, 1 H), 3.92 (s, 3 H), 3.82 (s, 3 H), 3.76 (s, 3 H), 3.51
(s, 3 H), 2.35 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ
= 159.6, 151.6, 149.8, 144.0, 143.1, 136.0, 131.3, 129.0, 128.8, 125.3,
114.0, 113.3, 113.1, 97.0, 65.8, 56.6, 56.5, 56.0, 55.2, 21.5 ppm.
HRMS-EI calcd. for C24H26O6S [M]+: 442.1450; found 442.1460.
Compound 14d: White solid; yield 398 mg (93%). 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 7.61 (d, J = 8.3 Hz, 2 H), 7.55 (s, 1
H), 7.49–7.46 (m, 3 H), 7.32 (t, J = 8.3 Hz, 1 H), 6.83 (d, J =
8.3 Hz, 2 H), 6.28 (s, 1 H), 5.95 (s, 1 H), 3.90 (s, 3 H), 3.79 (s, 3
H), 3.74 (s, 3 H), 3.46 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3,
25 °C): δ = 159.6, 151.6, 149.9, 143.1, 138.9, 133.2, 131.3,
128.8,128.4, 125.1, 114.0,113.2, 113.0, 96.9, 65.8, 56.7, 56.4, 56.0,
55.2 ppm.[3]
c) Characterization Data for the Products
Compound 12a: White solid; m.p. 110–111 °C; yield 317 mg
(83.0%). 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.00 (d, J =
8.0 Hz, 1 H), 7.64 (d, J = 8.5 Hz, 2 H), 7.56 (d, J = 8.5 Hz, 2 H),
7.36–7.33 (m, 3 H), 7.19 (d, J = 8.0 Hz, 2 H), 6.62 (d, J = 8.5 Hz,
1 H), 6.32 (s, 1 H), 6.03 (s, 1 H), 3.82 (s, 3 H), 3.54 (s, 3 H), 2.40
(s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 160.9, 157.9,
144.1, 136.0, 133.7, 130.8, 130.2, 129.0, 128.5 128.2, 114.3, 104.7,
98.3, 66.4, 55.4, 55.3, 21.6 ppm. HRMS-EI calcd. for C22H22O4S
[M]+: 382.1239; found 382.1263.
Compound 14e: White solid; m.p. 131–133 °C; yield 406 mg (92%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.62 (d, J = 8.4 Hz, 2 H),
7.57 (s, 1 H), 7.49–7.42 (m, 2 H), 7.33 (t, J = 7.6 Hz, 2 H), 7.27 (s,
Compound 12b: White solid; m.p. 88–90 °C; yield 354 mg (86%). 1 H), 6.76 (d, J = 8.4 Hz, 1 H), 6.27 (s, 1 H), 5.92 (s, 1 H), 3.91 (s,
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.82 (d, J = 8.2 Hz, 1 H),
3 H), 3.80 (s, 3 H), 3.77 (s, 3 H), 3.45 (s, 3 H), 2.16 (s, 3 H), 2.12
7.53–7.49 (m, 4 H), 7.29–7.27 (m, 3 H), 7.14 (d, J = 8.5 Hz, 2 H), (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 157.8, 151.5,
6.74 (d, J = 8.2 Hz, 1 H), 5.88 (s, 1 H), 3.84 (s, 3 H), 3.71 (s, 3 H), 149.8, 143.0, 138.9, 132.9, 128.7, 128.4, 128.2, 126.7, 124.3, 113.3,
3.58 (s, 3 H), 2.33 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 113.1, 109.8, 96.8, 65.7, 56.5, 56.2, 55.8, 55.1, 16.1 ppm. HRMS-
25 °C): δ = 153.9, 152.0, 144.2, 135.8, 133.6, 130.1, 129.2, 129.0,
EI calcd. for C24H26O6S [M]+: 442.1450; found 442.1460.
1804
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 1798–1808

Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
Compound 14f: White solid; m.p. 146–147 °C; yield 419 mg (92%).
Compound 14m: White solid; m.p. 157–158 °C; yield 383 mg (86%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.55 (s, 1 H), 7.47 (d, J 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.57–7.54 (m, 5 H), 7.32
= 8.2 Hz, 2 H), 7.37 (d, J = 8.0 Hz, 1 H), 7.22 (s, 1 H), 7.08 (d, J
= 8.2 Hz, 2 H), 6.71 (d, J = 8.0 Hz, 1 H), 6.26 (s, 1 H), 5.86 (s, 1 (s, 3 H), 3.88 (s, 3 H), 3.56 (s, 3 H), 2.42 (s, 3 H) ppm. 13C NMR
H), 3.87 (s, 3 H), 3.76 (s, 3 H), 3.73 (s, 3 H), 3.44 (s, 3 H), 2.29 (s, (50 MHz, CDCl3, 25 °C): δ = 151.6, 150.1, 144.3, 143.1, 135.6,
3 H), 2.12 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 135.5, 134.3, 130.1, 129.7, 129.1, 128.8, 128.4, 128.0, 112.9, 112.2,
(s, 2 H), 7.22 (d, J = 8.5 Hz, 2 H), 6.37 (s, 1 H), 5.99 (s, 1 H), 3.97
157.6, 151.4, 149.6, 143.7, 142.9, 135.9, 132.3, 128.8, 128.7, 128.3,
126.5, 124.5, 113.2, 113.1, 109.7, 96.8, 65.6, 56.5, 56.2, 55.8, 55.1,
21.3, 16.1 ppm. HRMS-EI calcd. for C25H28O6S [M]+: 456.1607;
found 456.1597.
96.7, 65.7, 56.6, 56.3, 55.9, 21.5 ppm. HRMS-EI calcd. for
C23H23ClO5S [M]+: 446.0955; found 446.0949.
Compound 14n: White solid; m.p. 146–147 °C; yield 370 mg (83%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.36 (d, J = 8.6 Hz, 1 H),
7.64 (d, J = 8.2 Hz, 2 H), 7.62 (s, 1 H), 7.46 (t, J = 8.6 Hz, 1 H),
Compound 14g: White solid; m.p. 131–132 °C; yield 404 mg (88%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.51 (s, 1 H), 7.50 (d, J 7.41 (d, J = 7.6 Hz, 1 H), 7.33 (t, J = 8.6 Hz, 1 H), 7.29 (d, J =
= 8.0 Hz, 2 H), 7.31–7.25 (m, 2 H), 7.15 (d, J = 8.6 Hz, 2 H), 6.89
(t, J = 8.4 Hz, 1 H), 6.31 (s, 1 H), 5.88 (s, 1 H), 3.91 (s, 3 H), 3.85
8.2 Hz, 2 H), 6.73 (s, 1 H), 6.47 (s, 1 H), 4.02 (s, 3 H), 3.95 (s, 3
H), 3.62 (s, 3 H), 2.49 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3,
(s, 3 H), 3.82 (s, 3 H), 3.50 (s, 3 H), 2.35 (s, 3 H) ppm. 13C NMR 25 °C): δ = 152.1, 150.0, 144.2, 142.8, 135.7, 135.1, 131.9, 130.4,
(100 MHz, CDCl3, 25 °C): δ = 153.1, 151.6, 150.7, 150.0, 147.7,
147.6, 144.2, 143.2, 135.7, 129.0, 128.8, 117.8, 117.7, 113.1, 112.7,
96.9, 65.3, 56.6, 56.4, 56.1, 55.9, 21.5 ppm. HRMS-EI calcd. for
C24H25FO6S [M]+: 460.1356; found 460.1344.
129.5, 129.2, 128.9, 128.8, 126.7, 113.4, 111.9, 96.6, 61.9, 56.4, 56.1,
55.7, 21.3 ppm. HRMS-EI calcd. for C23H23ClO5S [M]+: 446.0955;
found 446.0955.
Compound 14o: White solid; m.p. 141–142 °C; yield 411 mg (89%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.03 (s, 1 H), 7.81–7.78
Compound 14h: White solid; m.p. 186–187 °C; yield 438 mg (93%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.59 (s, 1 H), 7.52 (d, J (m, 3 H), 7.70 (dd, J = 8.0, 1.6 Hz, 1 H), 7.64 (d, J = 1.6 Hz, 1 H),
= 8.6 Hz, 2 H), 7.16 (d, J = 8.2 Hz, 2 H), 7.14 (d, J = 8.6 Hz, 1 7.54 (d, J = 8.5 Hz, 2 H), 7.47–7.45 (m, 2 H), 7.14 (d, J = 8.5 Hz,
H), 7.06 (s, 1 H), 6.82 (d, J = 8.2 Hz, 2 H), 6.35 (s, 1 H), 5.92 (s,
2 H), 6.34 (s, 1 H), 6.16 (s, 1 H), 3.93 (s, 3 H), 3.83 (s, 3 H), 3.53
1 H), 3.92 (s, 3 H), 3.85 (s, 3 H), 3.83 (s, 3 H), 3.53 (s, 3 H), 2.36
(s, 3 H), 2.35 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ
(s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 151.7, 149.9, = 151.7,149.9, 144.0, 143.1, 136.0, 133.1, 132.8, 131.0, 129.5, 129.0,
149.1, 148.7, 144.0, 143.1, 136.0, 129.0, 128.9, 125.6, 122.6, 113.2,
113.1, 111.0, 97.1, 66.0, 56.6, 56.4, 56.0, 55.8 (ϫ2) 21.5 ppm.
HRMS-EI calcd. for C25H28O7S [M]+: 472.1556; found 472.
128.8, 128.2, 128.1, 127.5, 127.2, 126.3, 126.1, 113.4, 113.0, 96.9,
66.5, 56.6, 55.9, 21.5 ppm. HRMS-EI calcd. for C23H23ClO5S
[M]+: 462.1501; found 462.1505.
1
Compound 14i: White solid; m.p. 156 °C; yield 454 mg (90%). 1H Compound 14p: White solid; m.p. 173 °C; yield 337 mg (84%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.55 (s, 1 H), 7.49 (d, J = NMR (400 MHz, CDCl3, 25 °C): δ = 7.48 (d, J = 8.0 Hz, 2 H),
8.0 Hz, 2 H), 7.13 (d, J = 8.4 Hz, 2 H), 6.77 (s, 1 H), 6.29 (s, 1 H),
7.42 (s, 1 H), 7.17 (d, J = 8.0 Hz, 2 H), 6.53 (d, J = 3.4 Hz, 1 H),
6.37–6.36 (m, 1 H), 6.34 (s, 1 H), 6.12 (s, 1 H), 3.87 (s, 3 H), 3.85
5.87 (s, 1 H), 3.88 (s, 3 H), 3.80 (s, 3 H), 3.78 (s, 9 H), 3.47 (s, 3
H), 2.33 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = (s, 3 H), 3.55 (s, 3 H), 2.38 (s, 3 H) ppm. 13C NMR (100 MHz,
153.0, 151.7, 150.0, 144.1, 143.1, 135.9, 129.0, 128.9, 128.8, 113.2,
112.7, 107.3, 96.9, 66.2, 60.8, 56.6, 56.3, 56.0, 56.0, 21.5 ppm.
HRMS-EI calcd. for C26H30O8S [M]+: 502.1661; found 502.1661.
CDCl3, 25 °C): δ = 151.9, 150.4, 146.2, 144.2, 143.4, 143.3, 135.2,
129.1, 129.0, 114.0, 111.8, 110.8, 110.4, 96.7, 61.3, 56.5, 56.4, 56.0,
21.6 ppm. HRMS-EI calcd. for C21H22O6S [M]+: 402.1137; found
402.1141.
1
Compound 14j: Yellow solid; m.p. 148 °C; yield 379 mg (83%). H
1
NMR (400 MHz, CDCl3, 25 °C): δ = 8.09 (d, J = 8.6 Hz, 2 H),
7.73 (d, J = 8.2 Hz, 2 H), 7.46 (d, J = 8.6 Hz, 2 H), 7.43 (s, 1 H),
7.11 (d, J = 8.2 Hz, 2 H), 6.28 (s, 1 H), 6.04 (s, 1 H), 3.84 (s, 3 H),
3.76 (s, 3 H), 3.44 (s, 3 H), 2.30 (s, 3 H) ppm. 13C NMR (50 MHz,
CDCl3, 25 °C): δ = 151.5, 150.2, 147.2, 144.5, 142.9, 140.8, 135.0,
130.7, 129.0, 128.5, 123.3, 112.6, 111.2, 96.5, 65.5, 56.4, 56.0, 55.7,
Compound 14q: White solid; m.p. 147 °C; yield 330 mg (79%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.47 (d, J = 8.0 Hz, 2 H),
7.44 (s, 1 H), 7.26 (d, J = 5.1 Hz, 1 H), 7.20 (d, J = 4.4 Hz, 1 H),
7.11 (d, J = 8.0 Hz, 2 H), 6.95 (dd, J = 5.1, 4.4 Hz, 1 H), 6.28 (s,
1 H), 6.23 (s, 1 H), 3.86 (s, 3 H), 3.81 (s, 3 H), 3.49 (s, 3 H), 2.33
(s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 151.6, 150.1,
21.3 ppm. HRMS-EI calcd. for C23H23NO7S [M]+: 457.1195; found 144.1, 142.9, 134.9, 134.4, 129.4, 128.9, 128.8, 126.6, 124.5, 113.1,
457.1189.
112.1, 96.6, 62.2, 56.8, 56.3, 55.8, 21.3 ppm. HRMS-EI calcd. for
C21H22O5S2 [M]+: 418.0909; found 418.0915.
Compound 14k: Yellow solid; yield 358 mg (82%). 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 7.65 (d, J = 8.4 Hz, 2 H), 7.56 (d,
J = 8.4 Hz, 2 H), 7.46 (d, J = 8.0 Hz, 2 H), 7.44 (s, 1 H), 7. 13 (d,
Compound 14r: White solid; m.p. 127–129 °C; yield 372 mg (89%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.39–7.30 (m, 3 H), 7.16
J = 8.4 Hz, 2 H), 6.27 (s, 1 H), 5.96 (s, 1 H), 3.86 (s, 3 H), 3.79 (s, (s, 1 H), 7.04 (d, J = 8.8 Hz, 2 H), 6.12 (s, 1 H), 4.69 (d, J = 6.5 Hz,
3 H), 3.46 (s, 3 H), 2.33 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 1 H), 3.89 (s, 3 H), 3.78 (s, 3 H), 3.35 (s, 3 H), 2.52–2.48 (m, 2 H),
25 °C): δ = 151.6, 150.3, 144.5, 143.1, 138.9, 135.3, 132.1, 130.6,
129.1, 128.7, 118.3, 112.8, 111.9, 111.5, 96.7, 66.9, 56.6, 56.1, 55.9,
21.5. MS (EI): m/z = 437 [M]+, 283, 282, 266 ppm.
2.42–2.38 (m, 2 H), 2.30 (s, 3 H), 1.80–1.76 (m, 2 H), 1.70–1.63 (m,
2 H), 1.39–1.14 (m, 3 H), 1.00–0.95 (m, 1 H) ppm. 13C NMR
(50 MHz, CDCl3, 25 °C): δ = 152.3, 149.5, 143.2, 143.0, 136.9,
128.4, 128.3, 128.1, 128.0, 112.6, 112.5, 96.3, 66.8, 66.1, 56.6, 56.0,
55.9, 38.2, 32.0, 30.6, 26.1, 25.9, 21.4 ppm. HRMS-EI calcd. for
C23H30O5S [M]+: 418.1814; found 418.1797.
Compound 14l: White solid; m.p. 137 °C; yield 396 mg (89%). 1H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.50–7.47 (m, 5 H), 7.25 (d,
J = 8.5 Hz, 2 H), 7.17 (d, J = 8.5 Hz, 2 H), 6.29 (s, 1 H), 5.93 (s,
1 H), 3.88 (s, 3 H), 3.79 (s, 3 H), 3.46 (s, 3 H), 2.32 (s, 3 H) ppm.
1
Compound 14s: White solid; m.p. 117 °C; yield 345 mg (83%). H
13C NMR (50 MHz, CDCl3): δ = 151.5, 149.9, 144.1, 143.0, 135.5, NMR (400 MHz, CDCl3, 25 °C): δ = 7.35 (d, J = 8.4 Hz, 2 H),
134.1, 132.0, 131.2, 128.9, 128.6, 128.5, 112.9, 112.3, 96.7, 65.5,
56.5, 56.1, 55.8, 21.3 ppm. HRMS-EI calcd. for C23H23ClO5S
[M]+: 446.0955; found 446.0955.
7.32 (s, 1 H), 7.31 (s, 1 H), 7.30–7.25 (m, 2 H), 7.10 (d, J = 14.0 Hz,
2 H), 7.01 (d, J = 8.0 Hz, 2 H), 6.09 (d, J = 5.6 Hz, 1 H), 5.06–
5.00 (m, 4 H), 4.74 (t, J = 8.0 Hz, 1 H), 3.85 (s, 3 H), 3.75 (s, 3 H),
Eur. J. Org. Chem. 2010, 1798–1808
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1805

P. Thirupathi, S. S. Kim
3.33 (s, 3 H), 2.79–2.56 (m, 2 H), 2.27 (s, 3 H), 2.04–1.89 (m, 3 H), 55.7, 55.1, 40.0 ppm. HRMS-EI calcd. for C26H27NO5 [M]+:
FULL PAPER
1.72–1.57 (m, 2 H), 1.29–1.20 (m, 1 H) ppm. 13C NMR (50 MHz,
CDCl3, 25 °C): δ = 156.8, 152.1, 151.9, 149.5, 143.0, 142.8, 136.3,
136.0, 128.1, 127.7, 111.9, 96.0, 66.3, 56.3, 55.5, 33.8, 29.3, 24.5,
24.4, 21.0 ppm. HRMS-EI calcd. for C23H28O5S [M]+: 416.1657;
found 416.1665.
433.1889; found 433.1885.
1
Compound 16d: White solid; m.p. 170 °C; yield 221 mg (53%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 8.09 (br. s, 1 H), 7.32 (d, J =
7.6 Hz, 1 H), 7.30 (d, J = 7.6 Hz, 1 H), 7.17 (t, J = 7.6 Hz, 1 H),
7.11 (s, 1 H), 7.06–7.00 (m, 2 H), 6.75 (d, J = 8.0 Hz, 1 H), 6.72
(s, 1 H), 6.64 (s, 1 H), 6.58 (s, 1 H), 6.03 (s, 1 H), 3.92 (s, 3 H),
3.82 (s, 3 H), 3.78 (s, 3 H), 3.64 (s, 3 H), 2.23 (s, 3 H) ppm. 13C
NMR (100 MHz, CDCl3, 25 °C): δ = 155.8, 151.1, 147.8, 142.7,
Compound 14t: White solid; m.p. 123–124 °C; yield 378 mg (86%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.43 (d, J = 8.5 Hz, 2 H),
7.36 (s, 1 H), 7.28–7.23 (m, 2 H), 7.20–7.13 (m, 3 H), 7.07 (d, J =
8.5 Hz, 2 H), 6.99 (s, 1 H), 6.30 (s, 1 H), 4.79 (d, J = 6.5 Hz, 1 H), 136.6, 135.7, 131.1, 126.9, 126.7, 125.8, 124.8, 123.7, 121.6, 119.9,
3.87 (s, 6 H), 3.37 (s, 3 H), 2.80–2.77 (m, 1 H), 2.68–2.43 (m, 1 H), 119.8, 118.5, 114.4, 111.0, 109.3, 98.1, 56.8, 56.5, 55.9, 55.1, 39.8,
2.42–2.38 (m, 1 H), 2.37 (s, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 16.2 ppm. HRMS-EI calcd. for C26H27NO4 [M]+: 417.1940; found
25 °C): δ = 151.9, 149.1, 143.0, 142.3, 139.6, 134.3, 128.0, 127.8,
127.5, 127.5, 127.4, 127.2, 127.1, 125.2, 110.5, 95.5, 65.7, 55.6, 55.0,
54.9, 31.7, 27.9, 20.6 ppm. HRMS-EI calcd. for C25H28O5S [M]+:
440.1657; found 440.1656.
417.1942.
Compound 16e: White solid; m.p. 172.9 °C; yield 250 mg (56%). 1H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.97 (br. s, 1 H), 7.17 (d, J =
8.8 Hz, 1 H), 7.05 (d, J = 2.0 Hz, 1 H), 6.99 (dd, J = 8.4, 2.0 Hz,
1 H), 6.81 (dd, J = 8.4, 2.0 Hz, 1 H), 7.72 (d, J = 8.8 Hz, 1 H),
7.71 (s, 1 H), 6.67 (s, 1 H), 6.59 (s, 1 H), 6.56 (d, J = 2.0 Hz, 1 H),
5.92 (s, 1 H), 3.89 (s, 3 H), 3.80 (s, 3 H), 3.75 (s, 3 H), 3.70 (s, 3
H), 3.62 (s, 3 H), 2.18 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 155.8, 151.1, 147.8, 142.7, 136.6, 135.7, 131.1, 126.9,
Compound 14u: White solid; m.p. 79 °C; yield 291 mg (77%). 1H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.37–7.29 (m, 4 H), 7.11 (s,
1 H), 7.00 (d, J = 7.4 Hz, 2 H), 6.10 (s, 1 H), 4.57 (d, J = 6.5 Hz,
1 H), 3.84 (s, 3 H), 3.75 (s, 3 H), 3.32 (s, 3 H), 2.77–2.74 (m, 1 H),
2.27 (s, 3 H), 1.26 (d, J = 6.5 Hz, 1 H), 0.89 (d, J = 6.5 Hz, 1
H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 152.2, 149.5, 126.7, 125.8, 124.8, 123.7, 121.6, 119.9, 119.8, 118.5, 114.4, 111.0,
143.2, 142.9, 136.7, 128.4, 128.3, 128.1, 112.5, 96.2, 66.7, 56.5, 55.9,
55.8, 28.7, 21.4, 21.3, 20.9 ppm. HRMS-EI calcd. for C20H26O5S
[M]+: 378.1501; found 378.1508.
109.3, 98.1, 56.8, 56.5, 55.9, 55.1, 39.8, 16.2 ppm. HRMS-EI calcd.
for C27H29NO5 [M]+: 447.2046; found 447.2050.
Compound 16f: White solid; m.p. 145–147 °C; yield 206 mg (49%).
Compound 14v: White solid; m.p. 85 °C; yield 283 mg (75%). 1H 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.95 (br. s, 1 H), 7.30 (d,
NMR (400 MHz, CDCl3, 25 °C): δ = 7.39 (d, J = 8.0 Hz, 2 H),
J = 8.4 Hz, 1 H), 7.23 (s, 1 H), 7.19 (d, J = 8.0 Hz, 3 H), 7.12 (t,
7.10 (d, J = 8.0 Hz, 2 H), 6.91 (s, 1 H), 6.21 (s, 1 H), 4.88 (d, J = J = 7.4 Hz, 1 H), 6.96 (d, J = 7.6 Hz, 1 H), 6.93 (d, J = 7.6 Hz, 1
12.0 Hz, 1 H), 3.81 (s, 3 H), 3.80 (s, 3 H), 3.33 (s, 3 H), 2.33 (s, 3
H), 6.89 (d, J = 7.6 Hz, 1 H), 6.82 (t, J = 8.4 Hz, 1 H), 6.56–6.54
H), 2.34–2.30 (m, 1 H), 2.14–1.98 (m, 1 H), 1.31–1.11 (m, 2 H),
(m, 3 H), 5.92 (s, 1 H), 3.86 (s, 3 H), 3.83 (s, 3 H), 3.71 (s, 3 H),
0.84 (t, J = 7.6 Hz, 3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): 3.56 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 153.3,
δ = 152.6, 149.8, 143.6, 143.2, 135.4, 128.8, 128.7, 128.7, 111.9,
96.5, 61.3, 56.5, 56.0, 55.8, 28.8, 21.5, 19.8, 13.5 ppm. HRMS-EI
calcd. for C20H26O5S [M]+: 378.1501; found 378.1508.
151.1, 151.0, 148.1, 145.6, 142.8, 137.5, 136.7, 126.9, 124.2, 123.8,
123.9, 122.0, 119.8, 119.4, 119.2, 116.5, 116.3, 114.1, 112.9, 110.9,
98.0, 56.9, 56.7, 56.1, 56.0, 40.0 ppm. MS (EI): m/z = 421 [M]+,
420, 319, 151 ppm.
1
Compound 16a: White solid; m.p. 169 °C; yield 171 mg (46%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.96 (br. s, 1 H), 7.33 (d, J =
8.6 Hz, 1 H), 7.28–7.13 (m, 6 H), 7.13 (d, J = 8.6 Hz, 1 H), 6.98
Compound 16g: White solid; m.p. 157–158 °C; yield 233 mg (54%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.02 (br. s, 1 H), 7.27 (d,
(t, J = 8.6 Hz, 1 H), 6.62 (s, 1 H), 6.58 (d, J = 1.6 Hz, 1 H), 6.03 J = 8.0 Hz, 1 H), 7.22 (d, J = 8.0 Hz, 1 H), 7.11 (t, J = 8.5 Hz, 1
(s, 1 H), 3.89 (s, 3 H), 3.73 (s, 3 H), 3.58 (s, 3 H) ppm. 13C NMR H), 6.94 (t, J = 8.5 Hz, 1 H), 6.79 (d, J = 2.0 Hz, 1 H), 6.73 (d, J
(100 MHz, CDCl3, 25 °C): δ = 151.2, 148.0, 144.2, 142.8, 136.7,
= 8.4 Hz, 1 H), 6.68 (dd, J = 8.4, 1.8 Hz, 1 H), 6.59 (s, 1 H), 6.55
(s, 1 H), 6.54 (d, J = 1.5 Hz, 1 H), 5.94 (s, 1 H), 3.86 (s, 3 H), 3.81
128.8, 128.0, 127.1, 125.9, 124.3, 123.8, 121.9, 120.0, 119.2, 114.4,
111.0, 98.1, 56.9, 56.6, 56.0, 40.8 ppm. HRMS-EI calcd. for (s, 3 H), 3.73 (s, 3 H), 3.71 (s, 3 H), 3.56 (s, 3 H) ppm. 13C NMR
C24H23NO3 [M]+: 373.1678; found 373.1700.
(100 MHz, CDCl3, 25 °C): δ = 151.2, 148.5, 148.0, 147.1, 136.8,
136.7, 127.0, 124.4, 123.7, 121.8, 120.6, 119.9, 119.1, 114.3, 112.4,
111.0, 110.7, 98.1, 56.9, 56.6, 56.0, 55.7, 40.3 ppm. HRMS-EI
calcd. for C26H27NO5 [M]+: 433.1889; found 433.1902.
Compound 16b: White solid; m.p. 179–180 °C; yield 221 mg (55%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.96 (br. s, 1 H), 7.31 (d,
J = 8.2 Hz, 1 H), 7.25 (d, J = 8.2 Hz, 1 H), 7.13 (d, J = 8.6 Hz, 3
H), 6.99 (t, J = 8.4 Hz, 1 H), 6.80 (d, J = 8.2 Hz, 2 H), 6.61 (s, 1 Compound 16h: White solid; m.p. 175–177 °C; yield 263 mg (57%).
H), 6.58 (d, J = 8.6 Hz, 1 H), 5.98 (s, 1 H), 3.89 (s, 3 H), 3.78 (s,
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.96 (br. s, 1 H), 7.19 (d,
3 H), 3.74 (s, 3 H), 3.59 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, J = 8.8 Hz, 1 H), 6.81 (s, 1 H), 6.70 (d, J = 2.0 Hz, 1 H), 6.75 (d,
25 °C): δ = 157.7, 151.2, 147.9, 142.9, 136.8, 136.4, 129.7, 127.1,
124.7, 123.8, 121.9, 120.2, 120.1, 119.2, 114.3, 113.4, 111.0, 98.2,
J = 8.4 Hz, 1 H), 6.74 (d, J = 1.8 Hz, 1 H), 6.69 (d, J = 8.8 Hz, 1
H), 6.68 (d, J = 2.0 Hz, 1 H), 6.62 (s, 1 H), 6.56 (s, 1 H), 5.91 (s,
57.0, 56.6, 56.1, 55.2, 40.0 ppm. HRMS-EI calcd. for C25H25NO4 1 H), 3.86 (s, 3 H), 3.84 (s, 3 H), 3.75 (s, 3 H), 3.73 (s, 3 H), 3.69
[M]+: 403.1784; found 403.1786.
(s, 3 H), 3.59 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C):
δ = 153.5, 151.2, 148.5, 147.9, 147.1, 142.8, 136.7, 131.9, 127.5,
124.5, 120.6, 119.6, 114.3, 112.4, 111.7, 110.7, 102.0, 98.1, 57.0,
56.6, 56.0, 55.7, 40.3 ppm. HRMS-EI calcd. for C27H29NO6 [M]+:
463.1995; found 463.1995.
Compound 16c: White solid; m.p. 150–152 °C; yield 259 mg (60%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.98 (br. s, 1 H), 7.22 (d,
J = 8.5 Hz, 1 H), 7.18 (d, J = 8.5 Hz, 2 H), 6.86–6.84 (m, 3 H),
6.71 (d, J = 1.5 Hz, 1 H), 6.67 (s, 1 H), 6.62 (s, 1 H), 6.58 (d, J =
1.5 Hz, 1 H), 5.96 (s, 1 H), 3.92 (s, 3 H), 3.81 (s, 3 H), 3.76 (s, 3 Compound 17a: White solid; m.p. 126–127 °C; yield 241 mg (57%).
H), 3.72 (s, 3 H), 3.64 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.26–7.21 (m 2 H), 7.17–
25 °C): δ = 157.6, 153.5, 151.2, 147.9, 142.8, 136.2, 131.9, 129.6,
127.4, 124.5, 119.6, 114.3, 113.3, 111.7, 111.5, 98.2, 56.9, 56.7, 56.0,
7.13 (m, 1 H), 7.04 (d, J = 8.2 Hz, 2 H), 6.54 (s, 2 H), 6.42 (s, 2
H), 6.07 (s, 1 H), 3.87 (s, 6 H), 3.65 (s, 6 H), 3.62 (s, 6 H) ppm. 13
C
1806
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Eur. J. Org. Chem. 2010, 1798–1808

Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes
NMR (50 MHz, CDCl3, 25 °C): δ = 151.5, 147.9, 144.2, 142.6,
128.9, 127.9, 125.7, 124.5, 114.5, 98.3, 57.0, 56.6, 56.0, 42.5 ppm.
HRMS-EI calcd. for C25H28O6 [M]+: 424.1886; found 424.1884.
8.0 Hz, 1 H), 7.25 (d, J = 8.0 Hz, 1 H), 7.12 (t, J = 8.0 Hz, 1 H),
7.00 (d, J = 1.5 Hz, 1 H), 6.97–6.94 (m, 2 H), 6.69 (d, J = 8.7 Hz,
1 H), 6.53 (s, 1 H), 6.50 (d, J = 8.7 Hz, 1 H), 5.88 (s, 1 H), 3.87 (s,
3 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 3.61 (s, 3 H), 2.19 (s, 3 H) ppm.
13C NMR (100 MHz, CDCl3, 25 °C): δ = 155.9, 151.9, 151.5, 142.2,
136.7, 135.9, 131.2, 130.7, 127.0, 126.8, 126.0, 123.9, 121.9, 120.6,
119.9, 119.1, 110.9, 109.5, 106.7, 60.8, 60.7, 55.8, 55.2, 40.6,
16.3 ppm. HRMS-EI calcd. for C26H27NO4 [M]+: 417.1940; found
417.1953.
1
Compound 17b: White solid; m.p. 131 °C; yield 290 mg (64%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.11 (d, J = 8.2 Hz, 2 H),
6.93 (d, J = 8.2 Hz, 2 H), 6.69 (s, 2 H), 6.58 (s, 2 H), 6.17 (s, 1 H),
4.02 (s, 6 H), 3.91 (s, 3 H), 3.80 (s, 6 H), 3.79 (s, 6 H) ppm. 13C
NMR (50 MHz, CDCl3, 25 °C): δ = 158.2, 152.1, 148.5, 143.2,
136.8, 130.5, 125.5, 115.0, 113.9, 99.0, 57.6, 57.2, 56.6, 55.7,
42.2 ppm. HRMS-EI calcd. for C26H30O7 [M]+: 454.1992; found
454.1993.
1
Compound E (R = 4-MePh): White solid; yield 332 mg (76%). H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.08 (d, J = 8.0 Hz, 2 H),
6.87 (d, J = 8.0 Hz, 2 H), 6.51 (s, 2 H), 6.42 (s, 2 H), 6.02 (s, 1 H),
3.87 (s, 3 H), 3.84 (s, 3 H), 3.63 (s, 6 H), 3.61 (s, 6 H), 2.27 (s, 3
H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 151.5, 147.9,
142.6, 141.0, 135.0, 128.8,128.6, 124.8, 114.5, 98.4, 57.0, 56.6, 56.0,
42.0, 20.9 ppm.
Compound 17c: White solid; m.p. 119–121 °C; yield 276 mg (59%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 6.84 (s, 1 H), 6.77 (d, J
= 8.0 Hz, 1 H), 6.68 (s, 2 H), 6.53 (s, 2 H), 6.44 (s, 2 H), 5.99 (s, 1
H), 3.87 (s, 6 H), 3.78 (s, 3 H), 3.66 (s, 6 H), 3.64 (s, 6 H), 2.13 (s,
3 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ = 155.8, 151.6,
147.9, 142.7, 135.6, 131.5, 126.9, 125.2, 114.6, 109.3, 98.5, 57.1,
56.7, 56.0, 55.2, 41.5, 16.3 ppm. HRMS-EI calcd. for C27H32O7
[M]+: 468.2128; found 468.2142.
Supporting Information (see also the footnote on the first page of
this article): General procedures, preparation of α-amido sulfones,
1H NMR and 13C NMR spectra and references.
Compound 17d: White solid; m.p. 110–111 °C; yield 304 mg (63%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 6.76 (d, J = 8.0 Hz, 1 H),
6.67 (d, J = 8.0 Hz, 1 H), 6.56 (s, 2 H), 6.53 (s, 1 H), 6.45 (s, 2 H),
6.03 (s, 1 H), 3.90 (s, 6 H), 3.86 (s, 3 H), 3.78 (s, 3 H), 3.69 (s, 6
H), 3.65 (s, 6 H) ppm. 13C NMR (50 MHz, CDCl3, 25 °C): δ =
151.5, 148.5, 148.0, 147.0, 142.7, 136.7, 124.8, 120.9, 114.4, 112.6,
110.5, 98.4, 57.1, 56.7, 56.0, 55.7, 42.0 ppm. HRMS-EI calcd. for
C27H32O8 [M]+: 484.2097; found 484.2096.
Acknowledgments
The authors thank the Centre for Biological Modulators of the
Korea Research Institute of Chemical Technology for the financial
support. We also acknowledge the assistance by BK21 provided by
the Korea Research Council.
Compound 17e: White solid; m.p. 97–99 °C; yield 308 mg (60%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 6.53 (s, 2 H), 6.44 (s, 2
H), 6.27 (s, 2 H), 5.99 (s, 1 H), 3.87 (s, 6 H), 3.81 (s, 3 H), 3.70 (s,
6 H), 3.68 (s, 6 H), 3.64 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 152.8, 151.6, 148.1, 139.8, 124.4, 114.4, 106.3, 98.3,
60.8, 57.1, 56.8, 56.0, 42.5 ppm. HRMS-EI calcd. for C28H34O9
[M]+: 514.2203; found 514.2201.
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Compound 17f: White solid; m.p. 168–169 °C; yield 256 mg (56%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.19 (d, J = 8.4 Hz, 2 H),
6.97 (d, J = 8.4 Hz, 2 H), 6.53 (s, 2 H), 6.39 (s, 2 H), 6.01 (s, 1 H),
3.87 (s, 6 H), 3.65 (s, 6 H), 3.63 (s, 6 H) ppm. 13C NMR (50 MHz,
CDCl3): δ = 151.5, 148.1, 142.9, 142.6, 131.3, 130.2, 128.0, 123.7,
114.3, 98.1, 56.8, 56.6, 56.0, 41.9 ppm. HRMS-EI calcd. for
C25H27ClO6 [M]+: 458.1496; found 458.1497.
Compound 17g: White solid; m.p. 126–127 °C; yield 238 mg (52%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.34 (d, J = 7.2 Hz, 1 H),
7.13–7.10 (m, 2 H), 6.87 (d, J = 7.2 Hz, 1 H), 6.54 (s, 2 H), 6.32
(s, 1 H), 6.31 (s, 2 H), 3.87 (s, 6 H), 3.66 (s, 6 H), 3.61 (s, 6 H) ppm.
13C NMR (50 MHz, CDCl3, 25 °C): δ = 151.6, 148.1, 142.5, 142.0,
134.3, 129.8, 129.4, 127.2, 126.0, 122.8, 114.1, 98.2, 56.8, 56.5, 55.9,
40.2 ppm. HRMS-EI calcd. for C25H27ClO6 [M]+: 458.1496; found
458.1492.
Compound 20: White solid; m.p. 138–140 °C; yield 410 mg (90%).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.81 (d, J = 8.7 Hz, 1 H),
7.51 (d, J = 8.0 Hz, 2 H), 7.37–7.34 (m, 2 H), 7.27 (s, 1 H), 7.15
(d, J = 8.4 Hz, 2 H), 6.74 (d, J = 8.7 Hz, 2 H), 5.80 (s, 1 H), 5.09
(s, 1 H), 3.84 (s, 3 H), 3.78 (s, 3 H), 3.70 (s, 3 H), 3.57 (s, 3 H), 2.34
(s, 3 H), 2.16 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ
= 157.8, 153.7, 151.9, 144.0, 141.7, 135.9, 132.3, 129.1, 129.0, 128.7,
128.5, 128.1, 126.7, 124.7, 124.3, 119.9, 109.8, 107.3, 66.6, 61.0,
60.5, 55.9, 55.2, 21.5, 16.2 ppm. HRMS-EI calcd. for C25H28O6S
[M]+: 456.1607; found 456.1597.
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Eur. J. Org. Chem. 2010, 1798–1808
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1807

P. Thirupathi, S. S. Kim
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Received: October 20, 2009
Published Online: January 20, 2010
1808
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Eur. J. Org. Chem. 2010, 1798–1808