Friedel-crafts arylation reactions of N -sulfonyl aldimines or sulfonamidesulfones with electron-rich arenes catalyzed by FeCl 3·6H2O: Synthesis of triarylmethanes and bis-heteroarylarylmethanes

Article abstract of DOI:10.1021/jo1010137

(Figure presented) The FeCl₃·6H₂O-catalyzed Friedel-Crafts arylation reactions of N-sulfonyl aldimines or sulfonamidesulfones with electron-rich arenes and heteroarenes, which lead to the formation of triarylmethanes and bis-heteroar

Full text of DOI:10.1021/jo1010137

pubs.acs.org/joc
Friedel-Crafts Arylation Reactions of N-Sulfonyl Aldimines or
Sulfonamidesulfones with Electron-Rich Arenes Catalyzed by FeCl3 6H2O:
Synthesis of Triarylmethanes and Bis-heteroarylarylmethanes
3
Ponnaboina Thirupathi and Sung Soo Kim*
Department of Chemistry, Inha University, Incheon 402-751, South Korea
sungsoo@inha.ac.kr
Received May 24, 2010
The FeCl3 6H2O-catalyzed Friedel-Crafts arylation reactions of N-sulfonyl aldimines or sulfona-
3
midesulfones with electron-rich arenes and heteroarenes, which lead to the formation of triaryl-
methanes and bis-heteroarylarylmethanes, are developed. The use of mild reaction conditions, low
catalytic loading, high yield, and single step synthesis are the advantages of the present procedure.
Introduction
reactions are usually assisted by either protic acid or Lewis
acid catalyst. The Friedel-Crafts arylation reactions of
carbonyl compounds,3 epoxides,4 and electron-deficient
olefins5 as substrates have been extensively studied. The
same reactions with imine substrates are completely atom-
economical access to obtain functionalized molecules,
which are potential starting materials for many biologi-
cally active compounds. However, the study of the Lewis
acid-catalyzed Friedel-Crafts arylation of imines is
limited to synthesis of 3-substituted indole derivatives.6
Very recently You and co-workers report an enantio-
selective synthesis of unsymmetriacal triarylmethanes
by chiral phosphoric acid.6d Tian and co-workers have
demonstrated the formation of bis-arylation of imines
with Bi2(SO4)3-TMSCl.7 Triarylmethanes and bis-hetero-
arylarylmethanes have been prepared by using Lewis
acid- or protic acid-catalyzed Friedel-Crafts arylation
reactions of aldehydes with electron-rich arenes and
Friedel-Crafts alkylation is one of the most important
C-C bond-forming reactions in organic chemistry.1,2 These
(1) Friedel, C.; Crafts, J. M. C. R. Hebd. Seances Acad. Sci. 1877, 84,
1392–1450.
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Alkylation Chemistry: A Century of Discovery; Dekker: New York, 1984. (c)
Olah, G. A. Friedel-Crafts and Related Reactions; Wiley: New York, NY,
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Published on Web 07/09/2010
DOI: 10.1021/jo1010137
r
2010 American Chemical Society

Thirupathi and Soo Kim
JOCArticle
SCHEME 1. General Preparation Method for the Synthesis of N-Sulfonyl Aldimines and Triarylmethanes
heteroarenes.8 The alcohols9 and R-amido sulfones10 are
also utilized for the Friedel-Crafts arylation reactions for
the preparation of triarylmethanes and bis-heteroarylaryl-
methane.
However, many of these methods are associated with one or
more drawbacks such as elevated temperature, long reaction
time, and multistep process with low yields. In continuation of
the development of useful synthetic methodology for C-C
bond forming reactions,9c,10,11 we report herein an efficient
salts have attracted attention from synthetic organic chemists
since iron is one of the most abundant metals. Many iron salts
are inexpensive and commercially available.12 These iron salts
have been found to show promising catalytic ability in many
organic transformations including Friedel-Crafts arylation
reactions.12a,g-j Friedel-Crafts arylation reactions of elec-
tron-rich arenes are a well-known process for the formation of
the C-C bond from the aromatic C-H bond.2
The triarylmethanes, bis-heteroarylarylmethanes, and dia-
rylalkanes have attracted considerable attention13 due
to biological activity as antiviral,14 antitumor,15 antituber-
cular,9a,16 antifungal,17 and anti-inflammatory agents.17
Moreover, these compounds have found widespread applica-
tion in synthetic, medicinal, and industrial chemistry.18 The
triarylmethyl derivatives are useful as protective groups,19
photochromic agents,20 and dyes.21 Ring-hydroxylated triar-
ylmethanes exhibit antitumor and antioxidant activities.8a
Moreover, diheteroarylmethanes are of interest for the food
industry as natural components of certain food and beverage
items as well as flavor agents in coffee.22
FeCl3 6H2O-catalyzed synthesis of triarylmethanes and bis-
3
heteroarylarylmethanes by Friedel-Crafts alkylation reac-
tions of N-sulfonyl aldimines or sulfonamidesulfones. Iron
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Result and Discussion
We have directed our studies toward the synthesis of triaryl-
methanes and bis-heterotriarylarylmethanes from N-sulfonyl
aldimines by Friedel-Crafts arylation reactions. The N-sulfo-
nyl aldimines (3) were prepared from the condensation of
aldehydes (1), sulfonamides, and sodium salt of arenesulfinic
acid to produce the sulfonamidesulfone (2) followed by treat-
ment with saturated aq NaHCO3 (Scheme 1).23
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J. Org. Chem. Vol. 75, No. 15, 2010 5241

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JOCArticle
TABLE 1. Optimization of the Reaction Conditions for Friedel-Crafts Arylation Reactions of N-Tosyl(4-chlorobenzylidene)-4-methylbenzenesulfo-
namide with 1,3,5-Trimethoxybenzenea
yield (%)b
entry
catalyst (mol %)
CuI (10)
RhI3 H2O (10)
BiCl3 (10)
Fe(acac)3 (10)
solvent
reaction time (h)
reaction temp (°C)
7a
8a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CHCl3
16
12
12
12
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
0-rt
0
-10
0-rt
0-rt
0-rt
0-rt
0-rt
NR
NR
NR
49
37
37
78
48
83
82
80
86
88
90
27
NR
78
NR
NR
NR
0
0
0
10
0
13
7
10
10
7
3
5.0
5.0
4.0
5.0
2.0
2.0
3.0
2.0
2.0
2.0
4.5
4.5
3.5
2.5
3.5
4.0
2.5
Fe(NO3)3 9H2O (10)
3
Fe(ClO4)3 xH2O (10)
3
FeCl2 4H2O (10)
3
FeCl3 6H2O (10)
3
FeCl3 (10)
FeBr3 (10)
FeCl3 6H2O (5)
3
FeCl3 6H2O (2.5)
FeCl3 6H2O (2.5)
3
4
0
3
FeCl3 6H2O (2.5)
FeCl3 6H2O (2.5)
3
NR
11
7
16
14
15
3
FeCl3 6H2O (2.5)
FeCl3 6H2O (2.5)
FeCl3 6H2O (2.5)
3
CH3CN
CH3OH
THF
89
60
47
79
3
3
FeCl3 6H2O (2.5)
FeCl3 6H2O (2.5)
3
CH3NO2
3
aReaction condition: N-tosyl(4-chlorobenzylidene)-4-methylbenzenesulfonamide (1.0 mmol) and 1,3,5-trimethoxybenzene (1.0 mmol) are used.
bYield of isolated product after column chromatography.
TABLE 2. Friedel-Crafts Arylation Reactions of Various N-Sulfonyl Aldimines with 1,3,5-Trimethoxybenzenea
yield (%)b
entry
R in 3
reaction time (h)
7
8
1
2
3
4
5
6
7
8
9
10
11
12
13
14
3a, 4-ClC6H4
3b, 3-ClC6H4
3c, 2-ClC6H4
3d, 4-BrC6H4
3e, C6H5
3f, 4-NO2C6H4
3g, 4-CNC6H4
3h, 3-CNC6H4
3i, 4-MeOC6H4
3j, 4-MeC6H4
3k, 2-furanyl
3l, 2-pyridinyl
3m, C6H5CH2CH2
3n, (CH3)2CH
2.0
3.0
3.5
2.0
2.5
3.5
3.5
3.5
2.0
2.0
2.0
3.0
2.5
2.5
7a, 90
7b, 88
7c, 84
7d, 91
7e, 87
7f, 87
7g, 89
7h, 86
7i, 82
7j, 90
7k,86
7l, 81
7m, 85
7n, 78
8a, 4
8b, 6
8c, 5
8d, 0
8e, 5
8f, 4
8g, 6
8h, 4
8i,14
8j, 0
8k, 0
8l, 0
8m, 0
8n, 0
aReaction condition: N-sulfonyl aldimines (1.0 mmol) and 1,3,5-trimethoxybenzene (1.0 mmol) are used at 0 °C-rt. bYield of isolated product after
column chromatography.
The reaction between N-tosyl(4-chlorobenzylidene)-4-
methylbenzenesulfonamide 3a and 1,3,5-trimethoxybenzene
6 for 16 h in the absence of catalyst did not take place at all
(entry 1). The reactions have been screened in the presence of
Fe(NO3)3 9H2O, Fe(ClO4)3 XH2O, FeCl2 4H2O, FeCl3
3
3
3
3
6H2O, FeCl3, and FeBr3 (entries 2-10). By considering the
amount of catalyst, the reaction time, and the yield, FeCl3 6H2O
(2.5 mol %) is suitable for the reaction (entry 13). The temp-
erature effect on the reaction is studied in CH2Cl2 (entries
3
various Lewis acids such as CuI, RhI3 H2O, BiCl3, Fe(acac)3,
3
5242 J. Org. Chem. Vol. 75, No. 15, 2010

Thirupathi and Soo Kim
JOCArticle
13-16). The reaction carried out at 0 °C-rt is found to be the
most effective (entry 14). The effect of various solvents is tested
(entries 14 and 17-21). CH2Cl2 is found to be the solvent of
choice in terms of yield and reaction time (entry 14) (Table 1).
The scope of the Friedel-Crafts arylation reactions of
various N-sulfonyl aldimines with 1,3,5-trimethoxybenzene
is evaluated and the results are summarized in Table 2. The
reaction of N-tosyl(4-chlorobenzylidene)-4-methylbenzene-
sulfonamide (3a) with 1,3,5-trimethoxybenzene (6) produces
the arylation product 7a in 90% yield, along with 4% of
triarylmethane 8a (entry 1). N-Tosyl(3-chlorobenzylidene)-
(3b), N-tosyl(2-chlorobenzylidene)- (3c), and N-tosyl(4-
bromobenzylidene)-4-methylbenzenesulfonamide (3d) react
with 1,3,5-trimethoxybenzene (6) to afford the arylation
products in 88%, 84%, and 91%, respectively (entries 2-4).
The reaction of N-tosyl(benzylidene)-4-methylbenzenesulfo-
namide (3e) with 1,3,5-trimethoxybenzene (6) gave the pro-
duct 7e (entry 5). The reaction of N-sulfonyl aldimines bearing
electron-withdrawing groups on the phenyl ring proceeded
smoothly to give the arylation products in good yields (entries
6-8). N-Sulfonyl aldimines with an electron-donating group
on the phenyl ring react with 1,3,5-trimethoxybenzene (6) to
obtain 7i and 7j in 82% and 90% yield, respectively (entries 9
and 10). Conspicuously there is hardly any substituent elec-
tronic effect on the Friedel-Crafts arylation reactions (com-
pare the yield of entries 6-10). 2-Furanyl (3k) and 2-pyridinyl
N-sulfonyl aldimines (3l) exhibit similar reactivity toward the
arylations (entries 11 and 12). The reactions of aralkyl (3m)
and aliphatic N-sulfonyl aldimines (3n) give the corresponding
products in 85% and 78%, respectively (entries 13 and 14).
The pure aliphatic structure without benzene ring (entry 14)
appears to yield a little lower yield.
7. Again the Fe(III) ion forms coordination with the nitrogen
atom to produce B. Subsequently the elimination of p-tolylsul-
fanimide from B and Fe(III) ion leads to the formation of oxo-
nium ion C. Oxonium ion C then reacts with 1,3,5-trimethoxy-
benzene 6 giving rise to the formation of triarylmethane 8.10b
TABLE 3. Synthesis of Triarylmethanes from N-Sulfonyl Aldimines
and 1,2,4-Trimethoxybenzenea
product
10
reaction
time (h)
yield
(%)b
entry
R in 3
3e, C6H5
3i, 4-MeOC6H4
3o, 3,4-(MeO)2C6H3
3j, 4-MeC6H4
3d, 4-BrC6H4
3a, 4-ClC6H4
3b, 3-ClC6H4
3c, 2-ClC6H4
3h, 3-CNC6H4
3g, 4-CNC6H4
1
2
3
4
5
6
7
8
9
10
10a
10b
10c
10d
10e
10f
10g
10h
10i
2.5
2.0
2.0
2.0
2.5
2.5
2.5
2.5
3.0
3.0
76
88
90
85
86
85
82
78
80
83
10j
aReaction condition: N-sulfonyl aldimines (1.0 mmol) and 1,2,4-
trimethoxybenzene (2.0 mmol) are used. bYield of isolated product after
column chromatography.
The Friedel-Crafts arylation reactions of N-sulfonyl aldi-
mines with 1,2,4-trimethoxybenzene generate the triaryl-
methanes (Table 3). Recently Deutsch and co-workers have
demonstrated the synthesis of triarylmethanes through ami-
doalkylation of arenes in two steps with poor yield (18-22%).24
Previously we have also reported the synthesis of triaryl-
methanes from R-amido sulfones in two steps with moderate
yield (56-67%).10a,b We are herein reporting the one-step syn-
thesis of triarylmethanes using N-sulfonyl aldimines (3). The
reaction of N-tosyl(benzylidene)-4-methylbenzenesulfonamide
(3e) with 1,2,4-trimethoxybenzene (9) affords 10a in 76% yield
(entry 1). N-Tosyl(4-methoxybenzylidene)- (3i), N-tosyl(3,4-di-
methoxybenzylidene)- (3o), and N-tosyl(4-methylbenzylidene)-
4-methylbenzenesulfonamide (3j) react with 1,2,4-trimethoxy-
benzene (11) to give the triarylmethanes in 88%, 90%, and 85%,
respectively (entries 2-4). The reactions of N-sulfonyl aldimines
(3) containing halogen groups of chlorine and bromine on the
phenyl ring proceed smoothly to produce 10e, 10f, 10g, and 10h
(entries 5-8). Interestingly, N-tosyl(3-cyanobenzylidene)- (3h)
and N-tosyl(4-cyanobenzylidene)-4-methylbenzenesulfonamide
(3g) treated with 1,2,4-trimethoxybenzene (9) produce the
triarylmethanes in 80% and 83%, respectively (entries 9 and
10). The present method is equally applicable for both electron-
donating as well as electron-withdrawing substrates for a similar
yield of triarylmethanes. This method shows better yield in
“one-step” compared to the “two-step” synthesis.10a,b,24
A plausible mechanism for the formation of 7 and 8 is pro-
posed in Figure 1. The first step is the formation of A, which is
formed by coordination of the N-sulfonyl aldimines 3 to Fe(III)
ion. N-Sulfonyl aldimine 3 is activated by Fe(III) ion to give
more electrophilicity at the imine carbon of A. The nucleophilic
carbon of 1,3,5-trimethoxybenzene 6 attacks on the imine car-
bon of A leading to the formation of the Fredel-Crafts product
The Friedel-Crafts arylation reactions of N-sulfonyl aldi-
mines with various electron-rich heteroarenes are examined
(Table 4). The N-tosyl(benzylidene)-4-methylbenzenesulfona-
mide (3e) is treated with indole (11a) in the presence of 5.0%
FIGURE 1. Plausible mechanism of FeCl3 6H2O-catalyzed Friedel-
Crafts arylation of N-sulfonyl aldimines with 1,3,5-trimethoxybenzene.
(24) Deutsch, J.; Checinski, M.; Kockritz, A.; Beller, M. Catal. Commun.
2009, 10, 373.
3
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JOCArticle
TABLE 4. Synthesis of Bis-heterotriarylarylmethanes from N-Sulfonyl
TABLE 5. Friedel-Crafts Arylation of N-Sulfonyl Aldimines with 1,3-
Aldimines and Electron-Rich Heteroarenesa
Dimethoxybenzene and Anisolea
product
12
reaction
time (h)
yield
(%)b
entry
R in 3
3e, C6H5
3e, C6H5
3e, C6H5
3i, 4-MeOC6H4
11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
11a
11b
11c
11a
12a
12b
12c
12d
12e
12f
12g
12h
12i
12j
12k
12l
12m
12n
2.5
2.0
2.5
2.0
2.5
2.0
2.5
2.0
2.0
2.0
3.0
3.0
3.0
3.0
88
90
82
87
86
84
82
92
90
87
85
78
80
71
product
14
reaction
time (h)
yield
(%)b
entry
R in 3
3e, C6H5
3j, 4-MeC6H4
3a, 4-ClC6H4
3b, 3-ClC6H4
3f, 4-NO2C6H4
3e, C6H5
13
3p, 4-MeO-3-MeC6H3 11a
1
2
3
4
5
6
13a
13a
13a
13a
13a
13b
14a
14b
14c
14d
14e
14f
2.0
2.0
2.0
2.0
3.0
6.0
55
61
58
54
52
53
3j, 4-MeC6H4
3a, 4-ClC6H4
3i, 4-MeOC6H4
3j, 4-MeC6H4
3d, 4-BrC6H4
3b, 3-ClC6H4
3h, 3-CNC6H4
3g, 4-CNC6H4
3n, (CH3)2CH
11a
11a
11b
11b
11b
11b
11b
11b
11b
aReaction condition: N-sulfonyl aldimines (1.0mmol) and 13 (2.0 mmol)
are used. bYield of isolated product after column chromatography.
(entry 1). N-Tosyl(4-methylbenzylidene)- (3j), N-tosyl(4-
chlorobenzylidene)- (3a), N-tosyl(3-chlorobenzylidene)-
(3b), and N-tosyl(4-nitrobenzylidene)-4-methylbenzene-
sulfonamide (3f) were treated with 1,3-dimethoxybenzene
(13a) to produce the corresponding triarylmethanes
(entries 2-5). Similarly, N-tosyl(benzylidene)-4-methyl-
benzenesulfonamide (3e) also reacts with anisole (13b) to
afford the regioselctive triarylmethane (entry 6).
aReaction condition: N-sulfonyl aldimines (1.0 mmol) and heteroar-
ene (2.0 mmol) are used. bYield of isolated product after column
chromatography.
FeCl3 6H2O. The reaction was taking place to produce
3
bis-heteroarylarylmethane 12a in 88% yield (entry 1). The
reactions of N-tosyl(benzylidene)-4-methylbenzenesulfonamide
(3e) with 2-methylfuran (11b) or 2-methylthiopene (11c) give
bis-heteroarylarylmethanes (entries 2 and 3). Similarly, N-tosyl-
(4-methoxybenzylidene)- (3i), N-tosyl(4-methoxy-3-methyl-
benzylidene)- (3p), N-tosyl(4-methylbenzylidene)- (3j) and N-
tosyl(4-chlorobenzylidene)-4-methylbenzenesulfonamide (3a)
react smoothly with indole (11a) to generate 12d, 12e, 12f, and
12g, respectively (entries 4-7). The reactions of N-tosyl(4-
methoxybenzylidene)- (3i), N-tosyl(4-methylbenzylidene)- (3j),
N-tosyl(4-bromobenzylidene)- (3d), and N-tosyl(3-chloroben-
zylidene)-4-methylbenzenesulfonamide (3b) with 2-methylfuran
(11b) were taking place to yield the products in 92%, 90%, 87%,
and 85% yield, respectively (entries 8-11). The reactions of N-
sulfonyl aldimines (3h and 3g) bearing an electron-withdrawing
group on the phenyl ring proceed smoothly to yield the bis-
heteroarylarylmethanes (entries 12 and 13). The presence of a
strongly electron-withdrawing group such as a cyano group in
R more or less reduces the yield. The isobutaryl group in
N-sulfonyl aldimine (3n) significantly decreases the yield of
diarylalkane 12n to 71% (entry 14).
The reaction of N-tosyl(4-bromobenzylidene)-4-methyl-
benzenesulfonamide (3d) with 1,3-dimethoxybenzene (13a)
in the presence of 2.5 mol % of FeCl3 6H2O produces the
3
alkylation product 15 in 68% yield (Scheme 2).
The Friedel-Crafts arylation reactions of various sulfo-
namidesulfones (precursors of N-sulfonyl aldimines) with
1,2,4-trimethoxybenzene or 2-methylfuran were examined
(Scheme 2). 4-Methyl-N-(phenyl(tosyl)methyl)sulfonamide
(16a) is treated with 1,2,4-trimethoxybenzene (9) for 4.5 h to
produce 10a in 58% yield. The reactions of N-(4-methoxy-
phenyl(tosyl)methyl)- (16b) with 4-methyl-N-(p-tolyl(tosyl)-
methyl)benzenesulfonamide (16c) bring about the triaryl-
methanes in good yield. Similarly, 4-methyl-N-(phenyl(tosyl)-
methyl)- (16a), N-(4-methoxyphenyl(tosyl)methyl)- (16b),
4-methyl-N-(p-tolyl(tosyl)methyl)- (16c), and 4-methyl-N-(4-
bromophenyl(tosyl)methyl)benzenesulfonamide (16d) under-
went reaction smoothly with 2-methylfuran (11b) to afford
the 12b, 12i, 12j, and 12k in 65%, 71%, 70%, and 67% yield,
respectively (Scheme 3).
The Friedel-Crafts arylation reactions of N-sulfonyl
aldimines with less activated arenes such as 1,3-dimethoxy-
benzene and anisole are examined and the results are sum-
marized in Table 5. The reaction of N-tosyl(benzylidene)-
4-methylbenzenesulfonamide (3e) with 1,3-dimethoxy-
benzene (13a) was completed to afford 14a in 55% yield
To investigate the applications and advantages of mono-
Friedel-Crafts arylation of N-sulfonyl aldimines with electron-
rich arenes, we focused on the one-pot synthesis of unsymmetrical
triarylmethanes (Table 6). The reaction between N-tosyl-
(4-chlorobenzylidene)-4-methylbenzenesulfonamide (3a) and
SCHEME 2. Friedel-Crafts Arylation of N-Tosyl(4-bromobenzylidene)-4-methylbenzenesulfonamide with 1,3-Dimethoxybenzene
5244 J. Org. Chem. Vol. 75, No. 15, 2010

Thirupathi and Soo Kim
JOCArticle
SCHEME 3. Synthesis of Triarylmethanes and Bis-heteroarylarylmethanes from Sulfonamidesulfones
TABLE 6. Friedel-Crafts Arylation Reactions of N-Sulfonyl Aldimines with 1,3,5-Trimethoxybenzene Followed by Addition of Indolea
reaction temp and time (h)
yield (%)b
entry
R
step I
step II
7
8
12
1
2
3
4
3a, 4-ClC6H4
3a, 4-ClC6H4
3e, C6H4
0 °C-rt, 2.0
0 °C-rt, 2.0
0 °C-rt, 2.5
0 °C-rt, 2.0
rt, 24
reflux, 8
rt, 24
rt, 8
7a, 5
8a, 5
8a, 8
8e, 4
8i, 12
12g, 18
12g, 21
12a, 12
12h, 38
7a, 60
7e, 68
7i, 41
3i, 4-CH3OC6H4
aReaction condition: N-sulfonyl aldimines (1.0 mmol), 1,3,5-trimethoxybenzene (1.0 mmol), and indole (1.0 mmol) are used. bYield of isolated
product after column chromatography.
SCHEME 4. Synthesis of Triarylmethanes: Comparison of Present Method with Literature
1,3,5-trimethoxybenzene (6) in the presence of 2.5% FeCl3
product 7a (65%) and the second Friedel-Crafts arylation
product 8a (5%). Unexpectedly, bis-indolylmethane (12g) is
also obtained in 18% yield (entry 1). After addition of indole
(11a) the reaction temperature was raised to reflux but there
was not much improvement in the yield (entry 2). Similarly,
3
6H2O at 0 °C-rt was stirred for 2.0 h and then 1 equiv of indole
(11a) was added to the mixture in same reaction pot. The
reaction mixture was again stirred for 24 h at rt. The major pro-
duct obtained in this reaction is mono-Friedel-Crafts arylation
J. Org. Chem. Vol. 75, No. 15, 2010 5245

Thirupathi and Soo Kim
JOCArticle
SCHEME 5. Synthesis of Bis-heteroarylmethanes: Comparison of Present Method with Literature
N-tosyl(benzylidene)- (3e) and N-tosyl(4-methoxybenzylidene)-4-
methylbenzenesulfonamide (3i) give 7e, 8e, and 12a and 7i, 8i, and
12h in 68%, 4%, and 12% and 41%, 12%, and 38%, respectively
(entries 3 and 4).
The synthesis of triarylmethane and bis-heteroarylmethane
by Friedel-Crafts arylation of N-sulfonyl aldimines with
electron-rich arenes is compared with other literature
(Scheme 4 and Scheme 5).
50.8, 21.2; HRMS-FAB (m/z) [M]þ calcd for C23H24O5NClS
461.1064, found 461.1061.
7b: white solid, mp 131-132 °C; 1H NMR (400 MHz, CDCl3)
δ 7.52 (d, J = 8.4 Hz, 2H), 7.25 (s, 1H), 7.16-7.12 (m, 3H), 7.02
(d, J = 8.4 Hz, 2H), 6.33 (d, J = 10.6 Hz, 1H), 6.08 (d, J = 10.6
Hz, 1H), 5.87 (s, 2H), 3.71 (s, 3H), 3.59 (s, 6H), 2.28 (s, 3H); 13
C
NMR (100 MHz, CDCl3) δ 161.0, 157.6, 143.6, 142.3, 137.2,
133.4, 129.0, 128.6, 126.6, 126.5, 126.4, 124.5, 107.9, 90.4, 55.4,
55.2, 50.9, 21.2; HRMS-FAB (m/z) [M]þ calcd for C23H24-
O5NClS 461.1064, found 461.1064.
1
Conclusions
7c: white solid, mp 124 °C; H NMR (400 MHz, CDCl3) δ
7.52 (d, J = 8.4 Hz, 2H), 7.37-7.34 (m, 1H), 7.28-7.26 (m, 1H),
7.11-7.07 (m, 2H), 7.02 (d, J = 8.4 Hz, 2H), 6.41 (d, J = 10.2
Hz, 1H), 5.98 (d, J = 10.2 Hz, 1H), 5.87 (s, 2H), 3.72 (s, 3H), 3.62
(s, 6H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 161.0,
158.1, 142.3, 138.2, 137.7, 133.5, 129.7, 129.4, 128.6, 128.1,
126.9, 125.9, 107.5, 90.6, 55.4, 55.2, 50.3, 21.3; HRMS-FAB
(m/z) [M]þ calcd for C23H24O5NClS 461.1064, found 461.1064.
FeCl3 6H2O-catalyzed Friedel-Crafts arylation reac-
3
tions of electron-rich arenes with N-sulfonyl aldimines or
sulfonamidesulfones are described. The identical catalytic
system is employed for the consecutive Friedel-Crafts reac-
tions. The advantages of the method include (1) low catalyst
loading and (2) mild reaction conditions.
1
7d:. white solid, mp 155 °C; H NMR (400 MHz, CDCl3) δ
7.48 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 8.4 Hz, 2H), 7.12 (d, J =
8.4 Hz, 2H), 6.97 (d, J = 8.0 Hz, 2H), 6.35 (d, J = 11.0 Hz, 1H),
6.03 (d, J = 10.6 Hz, 1H), 5.85 (s, 2H), 3.70 (s, 3H), 3.58 (s, 6H),
2.26 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.9, 157.5, 142.4,
140.6, 137.2, 130.7, 128.5, 128.1, 126.6, 120.1, 108.0, 90.3, 55.4,
55.1, 50.8, 21.1; HRMS-FAB (m/z) [M]þ calcd for C23H24O5-
NBrS 505.0559, found 505.0560.
Experimental Section
A. Experimental Procedure for the Friedel-Crafts Alkylation
of N-Sulfonyl Aldimines with 1,3,5-Trimethoxybenzne. To a
stirred solution of N-sulfonyl aldimines (1 mmol) and FeCl3
3
6H2O (2.5 mol %) in CH2Cl2 (3 mL) under nitrogen atmosphere
at 0 °C is added 1,3,5-trimethoxybenzne (1 mmol). The mixture
is stirred at 0 °C-rt and monitored by TLC. After completion,
the reaction mixture is filtered, and the residue is washed with
diethyl ether (3 ꢀ 5 mL). The filtrate is dried over anhydrous
Na2SO4 and concentrated under vacuum. The crude product is
subject to flash column chromatography (silica gel, hexane-
EtOAc, 4:1 to 3:1) to obtain the pure product.
7e: white solid, mp 167-168 °C; 1H NMR (400 MHz, CDCl3)
δ 7.50 (d, J = 8.0 Hz, 2H), 7.24-7.15 (m, 5H), 6.99 (d, J = 8.0
Hz, 2H), 6.21 (d, J = 11.0 Hz, 1H), 6.10 (d, J = 11.0 Hz, 1H),
5.88 (s, 2H), 3.74 (s, 3H), 3.62 (s, 6H), 2.30 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ 160.8, 157.9, 142.3, 141.3, 137.6, 128.6,
127.9, 126.8, 126.5, 126.4, 90.6, 55.6, 55.3, 51.5, 21.3; HRMS-
FAB (m/z) [M]þ calcd for C23H24O5NS 427.1453, found
427.1455.
ACS reagent grade FeCl3 6H2O is used for the reaction. The
3
purity of FeCl3 6H2O is 97% (CAS No 10025-77-1, Sigma-Aldrich).
3
The products were characterized by 1H and 13C NMR
data that are consistent with literature values. Melting point,
HRMS-FAB, and 1H and 13C NMR values for the new products
are given below.
1
7f: yellow solid, mp 135 °C; H NMR (400 MHz, CDCl3) δ
8.06 (d, J = 8.8 Hz, 2H), 7.53 (d, J = 8.0 Hz, 2H), 7.42 (d, J =
8.8 Hz, 2H), 7.05 (d, J = 8.4 Hz, 2H), 6.22 (d, J = 10.6 Hz, 1H),
6.14 (d, J = 10.6 Hz, 1H), 5.91 (s, 2H), 3.75 (s, 3H), 3.63 (s, 6H),
2.32 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 161.4, 157.6, 149.4,
146.6, 142.8, 137.2, 128.8, 127.1, 126.8, 123.1, 107.8, 90.5, 55.6,
51.0, 21.3; HRMS-FAB (m/z) [M]þ calcd for C23H24O7N2S
472.1304, found 472.1302.
7a: white solid, mp 168-169 °C; 1H NMR (400 MHz, CDCl3)
δ 7.49 (d, J = 8.4 Hz, 2H), 7.18 (d, J = 7.6 Hz, 2H), 7.14 (d, J =
7.6 Hz, 2H), 6.99 (d, J = 8.4 Hz, 2H), 6.33 (d, J = 10.6 Hz, 1H),
6.05 (d, J = 10.6 Hz, 1H), 5.90 (s, 2H), 3.74 (s, 3H), 3.62 (s, 6H),
2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.9, 157.6, 142.4,
140.0, 137.2, 132.0, 128.6, 127.7, 126.6, 108.0, 90.4, 55.4, 55.2,
7g: white solid, mp 164-165 °C; 1H NMR (400 MHz, CDCl3)
δ 7.49 (d, J = 8.4 Hz, 2H), 7.43 (d, J = 8.4 Hz, 2H), 7.35 (d,
5246 J. Org. Chem. Vol. 75, No. 15, 2010

Thirupathi and Soo Kim
JOCArticle
J = 8.4 Hz, 2H), 6.99 (d, J = 8.7 Hz, 2H), 6.39 (d, J = 10.6 Hz,
1H), 6.09 (d, J = 10.2 Hz, 1H), 5.86 (s, 2H), 3.73 (s, 3H), 3.61 (s,
6H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 161.1, 157.5,
147.2, 142.8, 137.1, 131.5, 128.6, 126.9, 126.9, 126.6, 118.8,
109.9, 107.5, 90.3, 55.4, 55.1, 51.0, 21.1; HRMS-FAB (m/z)
[M]þ calcd. for C24H24O5N2S 452.1406, found 452.1404.
6.10 (s, 4H), 3.78 (s, 6H), 3.51 (s, 12H); 13C NMR (100 MHz,
CDCl3) δ 159.6, 159.1, 144.2, 129.4, 129.0, 126.9, 113.4, 91.6,
55.9, 55.9, 55.0, 36.4; HRMS-EI (m/z) [M]þ calcd for C25H27-
ClO6 458.1496, found 458.1497.
8b: white solid; mp 160-161 °C; 1H NMR (400 MHz, CDCl3)
δ 7.07-7.00 (m, 3H), 6.91 (d, J = 7.4 Hz, 1H), 6.17 (s, 1H), 6.12
(s, 4H), 3.80 (s, 6H), 3.53 (s, 12H); 13C NMR (100 MHz, CDCl3)
δ 159.7, 159.3, 148.1, 132.8, 128.1, 127.9, 126.0, 124.2, 113.2,
91.6, 56.0, 55.0, 36.8; HRMS-EI (m/z) [M]þ calcd for C25H27-
ClO6 458.1496, found 458.1497.
1
7h: white solid, mp 145 °C; H NMR (400 MHz, CDCl3) δ
7.60 (d, J = 7.8 Hz, 1H), 7.50 (d, J = 8.0 Hz, 2H), 7.44-7.40 (m,
2H), 7.34-7.29 (m, 1H), 7.02 (d, J = 8.0 Hz, 2H), 6.25 (d, J =
10.6 Hz, 1H), 6.07 (d, J = 10.6 Hz, 1H), 5.89 (s, 2H), 3.74 (s, 3H),
3.61 (s, 6H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 161.3,
157.6, 143.2, 142.7, 137.2, 131.1, 130.2, 129.9, 128.8, 128.7,
126.8, 119.0, 111.8, 107.6, 90.5, 55.6, 55.3, 50.8, 21.3; HRMS-
FAB (m/z) [M]þ calcd for C24H24O5N2S 452.1406, found
452.1405.
1
8c: white solid; mp 200 °C; H NMR (400 MHz, CDCl3) δ
7.24 (d, J = 8.4 Hz, 1H), 7.05-7.03 (m, 3H), 6.30 (s, 1H), 6.11 (s,
4H), 3.78 (s, 6H), 3.50 (s, 12H); 13C NMR (100 MHz, CDCl3) δ
159.7, 159.1, 142.8, 133.4, 130.4, 128.1, 125.8, 125.6, 113.7, 92.0,
56.3, 56.3, 55.1, 35.8; HRMS-EI (m/z) [M]þ calcd for
C25H27ClO6 458.1496, found 458.1492.
7i: white solid, mp 153 °C; 1H NMR (400 MHz, CDCl3) δ 7.49
(d, J = 8.1 Hz, 2H), 7.15 (d, J = 8.4 Hz, 2H), 6.99 (d, J = 8.1 Hz,
2H), 6.74 (d, J = 8.8 Hz, 2H), 6.21 (d, J = 10.6 Hz, 1H), 6.05 (d,
J = 11.0 Hz, 1H), 5.87 (s, 2H), 3.74 (s, 3H), 3.73 (s, 3H), 3.62 (s,
6H), 2.29 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.7, 158.3,
157.8, 142.3, 137.5, 133.3, 128.6, 127.6, 127.8, 113.2, 198.7, 90.5,
55.5, 55.2, 55.1, 51.1, 21.3; HRMS-FAB (m/z) [M]þ calcd for
C24H27O6NS 457.1559, found 457.1561.
1
8e: white solid; mp 191 °C; H NMR (400 MHz, CDCl3) δ
7.16-7.12 (m, 2H), 7.05-7.03 (m, 3H), 6.21 (s, 1H), 6.11 (s, 4H),
3.78 (s, 6H), 3.49 (s, 12H); 13C NMR (100 MHz, CDCl3) δ
1159.7, 159.1, 142.8, 133.4, 130.4, 128.1, 125.8, 125.6, 113.7,
92.0, 56.3, 56.3, 55.1, 35.8.8b
8f: yellow solid; mp 159-160 °C; 1H NMR (400 MHz,
CDCl3) δ 8.00 (d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 2H),
6.26 (s, 1H), 6.10 (s, 4H), 3.79 (s, 6H), 3.52 (s, 12H); 13C NMR
(100 MHz, CDCl3) δ 159.6, 159.6, 154.8, 145.1, 128.4, 122.4,
112.2, 91.4, 55.9, 55.2, 37.2.8b
7j: white solid, mp 165-166 °C; 1H NMR (400 MHz, CDCl3)
δ 7.49 (d, J = 8.1 Hz, 2H), 7.13 (d, J = 8.1 Hz, 2H), 7.00 (d, J =
8.4 Hz, 2H), 6.98 (d, J = 8.4 Hz, 2H), 6.24 (d, J = 11.0 Hz, 1H),
6.07 (d, J = 11.0 Hz, 1H), 5.87 (s, 2H), 3.72 (s, 3H), 3.61 (s, 6H),
2.28 (s, 3H), 2.26 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.7,
157.8, 142.2, 138.2, 137.5, 136.0, 128.5, 126.7, 126.3, 108.6, 90.5,
55.5, 55.2, 51.3, 21.2, 20.9; HRMS-FAB (m/z) [M]þ calcd for
C24H27O5NS 441.1610, found 441.1612.
8g: white solid; mp 153-154 °C; 1H NMR (400 MHz, CDCl3)
δ 7.43 (d, J = 8.2 Hz, 2H), 7.13 (d, J = 8.2 Hz, 2H), 6.24 (s, 1H),
6.10 (s, 4H), 3.79 (s, 6H), 3.51 (s, 12H); 13C NMR (100 MHz,
CDCl3) δ 159.6, 159.5, 152.2, 130.9, 128.4, 119.9, 112.3, 107.5,
91.5, 55.9, 55.1, 37.2; HRMS-EI (m/z) [M]þ calcd for C26H27-
NO6 449.1838, found 449.1840.
1
7k: white solid, mp 127 °C; H NMR (400 MHz, CDCl3) δ
1
7.52 (d, J = 8.0 Hz, 2H), 7.22 (s, 1H), 7.02 (d, J = 8.0 Hz, 2H),
6.20-6.18 (m, 1H), 6.15 (d, J = 11.0 Hz, 1H), 6.12 (d, J = 10.6
Hz, 1H), 5.98 (d. J = 3.3 Hz, 1H), 5.90 (s, 2H), 3.74 (s, 3H), 3.67
(s, 6H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 161.0,
158.1, 153.6, 142.4, 141.6, 137.6, 128.7, 126.8, 110.0, 106.7,
106.3, 94.4, 90.7, 55.7, 55.2, 46.9, 21.3; HRMS-FAB (m/z)
[M]þ calcd for C21H23O6NS 417.1246, found 417.1245.
7l: white solid, mp 162-163 °C; 1H NMR (400 MHz, CDCl3)
δ 8.38 (d, J = 5.0 Hz, 1H), 7.54 (d, J = 8.0 Hz, 2H), 7.51 (d, J =
7.3 Hz, 1H), 7.34 (d, J = 7.6 Hz, 1H), 7.54 (d, J = 8.0 Hz, 3H),
6.57 (d, J = 9.5 Hz, 1H), 6.17 (d, J = 9.1 Hz, 1H), 5.89 (s, 2H),
3.71 (s, 3H), 3.58 (s, 6H), 2.29 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 160.9, 159.9, 158.1, 148.1, 142.2, 137.6, 135.9, 128.6,
126.9, 121.3, 120.9, 109.5, 90.7, 55.6, 55.1, 52.1, 21.3; HRMS-
FAB (m/z) [M þ H]þ calcd for C22H25O5N2S 429.1484, found
429.1485.
8h: white solid; mp 139 °C; H NMR (400 MHz, CDCl3) δ
7.34-7.22 (m, 4H), 6.20 (s, 1H), 6.10 (s, 4H), 3.79 (s, 6H), 3.52 (s,
12H); 13C NMR (100 MHz, CDCl3) δ 159.6, 159.5, 147.4, 132.5,
131.6, 128.0, 127.6, 120.0, 112.3, 110.7, 91.4, 55.8, 55.1, 36.7; HRMS-
EI (m/z) [M]þ calcd for C26H27NO6 449.1838, found 449.1836.
8i: white solid; mp 133-134 °C; 1H NMR (400 MHz, CDCl3)
δ 6.97 (d, J = 8.4 Hz, 2H), 6.70 (d, J = 8.0 Hz, 2H), 6.15 (s, 1H),
6.10 (s, 4H), 3.78 (s, 6H), 3.50 (s, 12H); 13C NMR (100 MHz,
CDCl3) δ 159.8, 159.0, 156.6, 137.7, 133.7, 129.7, 128.7, 127.9,
114.6, 112.4, 91.9, 56.2, 55.1, 36.3; HRMS-EI (m/z) [M]þ calcd
for C26H30O7 454.1992, found 454.1993.
B. Experimental Procedure for the Synthesis of Triaryl-
methanes or Heterotriarylmethanes. To a mixture of of N-
sulfonyl aldimines or sulfonamidesulfones (1 mmol) and
FeCl3 6H2O (5.0 mol %) in CH2Cl2 (3 mL) under nitrogen,
3
electron-rich arene or heteroarene (2.0 mmol) is added and the
mixture is stirred at rt. The progress of the reaction mixture is
monitored by TLC. After completion of the reaction, the
mixture is filtered, and the residue is washed with diethyl ether
(3 ꢀ 5 mL). The combined organic portions were washed with
water (5 mL) and saturated aqueous NH4Cl (5 mL), dried over
anhydrous Na2SO4, and concentrated under vacuum. The crude
product is subjected to flash column chromatography (silica gel,
hexane-EtOAc, 4:1 to 3:1) to obtain pure product.
7m: white solid, mp 114 °C; 1H NMR (400 MHz, CDCl3) δ
7.43 (d, J = 8.4 Hz, 2H), 7.24-7.19 (m, 2H), 7.13-7.10 (m, 3H),
6.94 (d, J = 8.0 Hz, 2H), 5.84 (d, J = 11.0 Hz, 1H), 5.80 (s, 2H),
4.91-4.84 (m, 1H), 3.70 (s, 3H), 3.64 (s, 6H), 2.80-2.72 (m, 1H),
2.51-2.43 (m, 1H), 2.25 (s, 3H), 2.16-2.07 (m, 1H), 1.93-1.83
(m, 1H); 13C NMR (100 MHz, CDCl3) δ 160.4, 142.2, 142.1,
137.6, 128.5, 128.3, 128.1, 126.7, 125.5, 108.9, 90.3, 55.4, 55.2,
49.3, 37.2, 32.6, 21.2; HRMS-FAB (m/z) [M]þ calcd for
C25H29O5NS 455.1766, found 455.1765.
10a: white solid, mp 126-127 °C; 1H NMR (400 MHz,
CDCl3) δ 7.26-7.21 m 2H), 7.17-7.13 (m, 1H), 7.04 (d, J =
8.2 Hz, 2H), 6.54 (s, 2H), 6.42 (s, 2H), 6.07 (s, 1H), 3.87 (s, 6H),
3.65 (s, 6H), 3.62 (s, 6H); 13C NMR (50 MHz, CDCl3) 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, 42.5.8e,10a,b
7n: white solid, mp 139-140 °C; 1H NMR (400 MHz, CDCl3)
δ 7.39 (d, J = 8.4 Hz, 2H), 6.92 (d, J = 8.0 Hz, 2H), 5.83 (s, 2H),
5.76 (d, J = 11.0 Hz, 1H), 4.44-4.38 (m, 1H), 3.70 (s, 6H), 3.58
(s, 3H), 2.25 (s, 3H), 2.05-1.95 (m, 1H), 1.09 (d, J = 8.0 Hz,
3H), 0.63 (d, J = 7.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
160.2, 157.8, 157.7, 141.9, 137.6, 129.6, 128.3, 126.6, 126.4,
108.7, 90.5, 89.8, 55.6, 55.2, 32.6, 21.2, 20.1, 19.3; HRMS-
FAB (m/z) [M þ H]þ calcd for C20H27NO5S 394.1688, found
394.1688.
10b: white solid, mp 131 °C; 1H NMR (400 MHz, CDCl3) δ
7.11 (d, J = 8.2 Hz, 2H), 6.93 (d, J = 8.2 Hz, 2H), 6.69 (s, 2H),
6.58 (s, 2H), 6.17 (s, 1H), 4.02 (s, 6H), 3.91 (s, 3H), 3.80 (s, 6H),
3.79 (s, 6H); 13C NMR (50 MHz, CDCl3) 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, 42.2.8e,10a,b
1
8a: white solid, mp 170 °C; H NMR (400 MHz, CDCl3) δ
7.09 (d, J = 8.4 Hz, 2H), 6.96 (d, J = 8.4 Hz, 2H), 6.15 (s, 1H),
J. Org. Chem. Vol. 75, No. 15, 2010 5247

Thirupathi and Soo Kim
JOCArticle
10c: white solid, mp 110-111 °C; 1H NMR (400 MHz,
CDCl3, 25 °C) δ 6.76 (d, J = 8.0 Hz, 1H), 6.67 (d, J = 8.0
Hz, 1H), 6.56 (s, 2H), 6.53 (s, 1H), 6.45 (s, 2H), 6.03 (s, 1H), 3.90
Hz, 2H), 6.82 (d, J = 8.0 Hz, 2H), 6.61 (d, J = 1.6 Hz, 2H), 5.85
(s, 1H), 3.81 (3H, s); 13C NMR (100 MHz, CDCl3) δ 157.8,
136.6, 136.2, 129.6, 127.0, 123.5, 121.8, 120.0, 119.9, 119.1,
113.5, 110.9, 60.4, 55.2.8i
(s, 6H), 3.86 (s, 3H), 3.78 (s, 3H), 3.69 (s, 6H), 3.65 (s, 6H); 13
C
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, 42.0.8e,10a,b
12e: brown solid; mp 137-138 °C; 1H NMR (400 MHz,
CDCl3) δ 7.69 (br s, 2H), 7.47 (d, J = 8.0 Hz, 2H), 7.30 (d,
J = 7.8 Hz, 2H), 7.22 (d, J = 1.5 Hz, 1H), 7.20 (t, J = 8.0 Hz,
2H), 7.13 (dd, J = 8.2, 1.5 Hz, 1H), 7.06 (d, J = 8.0 Hz, 2H), 6.75
(d, J = 8.2 Hz, 1H), 6.58 (d, J = 1.5 Hz, 1H), 5.86 (s, 1H), 3.82
(s, 3H), 2.23 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 156.0,
136.6, 135.7, 130.9, 127.0, 126.6, 125.9, 123.7, 121.7, 119.9,
119.8, 119.0, 111.0, 109.6, 60.4, 55.2, 16.3.10a
10d: white solid; mp 142-143 °C; 1H NMR (400 MHz,
CDCl3) δ 7.08 (d, J = 8.0 Hz, 2H), 6.87 (d, J = 8.0 Hz, 2H),
6.51 (s, 2H), 6.42 (s, 2H), 6.02 (s, 1H), 3.87 (s, 3H), 3.84 (s, 3H),
3.63 (s, 6H), 3.61 (s, 6H), 2.27 (s, 3H); 13C NMR (100 MHz,
CDCl3) 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, 20.9.8e
1
12f: pale brown solid; mp 96-97 °C; H NMR (400 MHz,
1
10e: white solid; mp 141 °C; H NMR (400 MHz, CDCl3)
CDCl3) δ 7.76 (br s, 2H), 7.38 (d, J = 7.2 Hz, 2H), 7.30 (d, J =
7.5 Hz, 2H), 7.21 (d, J = 7.5 Hz, 2H), 7.15 (t, J = 7.2 Hz, 2H),
7.07 (d, J = 7.2 Hz, 2H), 6.99 (d, J = 7.2 Hz, 2H), 6.59 (d, J =
1.5 Hz, 2H), 5.83 (s, 1H), 2.30 (s, 3H); 13C NMR (50 MHz,
CDCl3) δ 141.0, 136.7, 135.5, 128.9, 128.6, 127.1, 123.6, 121.9,
120.0, 119.9, 119.2, 111.0, 39.8, 21.1.8i
δ 7.30 (d, J = 8.4 Hz, 2H), 6.88 (d, J = 8.4 Hz, 2H), 6.50 (s,
2H), 6.36 (s, 2H), 5.96 (s, 1H), 3.82 (s, 6H), 3.62 (s, 6H), 3.60
(s, 6H); 13C NMR (50 MHz, CDCl3) δ 151.5, 148.2,142.7,
131.0, 130.7, 128.8, 123.6, 119.5, 114.4, 98.2, 56.8, 56.7, 56.0,
42.1.8e
10f: white solid; mp 168-169 °C; 1H NMR (400 MHz,
CDCl3) δ 7.19 (d, J = 8.4 Hz, 2H), 6.97 (d, J = 8.4 Hz, 2H),
6.53 (s, 2H), 6.39 (s, 2H), 6.01 (s, 1H), 3.87 (s, 6H), 3.65 (s, 6H),
3.63 (s, 6H); 13C NMR (100 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,
41.9.8e,10a,b
12g: pale brown solid; mp 79-80 °C; H NMR (400 MHz,
1
CDCl3) δ 7.75 (br s, 2H), 7.43 (d, J = 8.0 Hz, 2H), 7.33-7.22 (m,
8H), 7.06 (t, J = 7.8 Hz, 2H), 6.54 (s, 2H), 5.90 (s, 1H); 13C
NMR (100 MHz, CDCl3) δ 142.6, 136.6, 131.6, 129.9, 129.8,
126.7, 123.5, 121.9, 119.7, 199.2, 188.9, 111.1, 60.5.8i
12h: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.17 (d, J =
8.2 Hz, 2H), 6.84 (d, J = 8.2 Hz, 2H), 5.88-5.84 (m, 4H), 5.29 (s,
1H), 3.77 (s, 3H), 2.24 (s, 6H); 13C NMR (100 MHz, CDCl3) δ
158.5, 153.1, 151.3, 132.1, 129.3, 113.7, 107.9, 106.0, 55.1, 44.3,
13.5; HRMS-FAB (m/z) [M]þ calcd for C18H18O3 282.1256,
found 282.1251.
10g: white solid; mp 169 °C; 1H NMR (400 MHz, CDCl3) δ
7.16-7.14 (m, 2H), 7.03-7.01 (m, 1H), 6.94-6.91 (m, 1H), 6.54
(s, 2H), 6.40 (s, 2H), 6.03 (s, 1H), 3.87 (s, 6H), 3.64 (s, 6H), 3.61
(s, 6H); 13C NMR (100 MHz, CDCl3) δ 151.5, 148.2, 146.7,
133.8, 129.1, 129.0, 127.1, 125.9, 123.5, 114.5, 98.2, 56.8, 56.7,
56.0, 42.3; HRMS-EI (m/z) [M]þ calcd for C25H27ClO6
458.1496, found 458.1497.
12i: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.21 (d, J =
7.8 Hz, 2H), 7.17 (d, J = 7.8 Hz, 2H), 5.93 (s, 4H), 5.37 (s, 1H),
2.38 (s, 3H), 2.29 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 153.0,
151.2, 137.0, 136.4, 129.0, 128.2, 107.9, 106.0, 44.7, 21.0, 13.5;
HRMS-FAB (m/z) [M]þ calcd for C18H18O2 266.1307, found
266.1304.
10h: white solid; mp 126-127 °C; 1H NMR (400 MHz,
CDCl3) δ 7.34 (d, J = 7.2 Hz, 1H), 7.13-7.10 (m, 2H), 6.87
(d, J = 7.2 Hz, 1H), 6.54 (s, 2H), 6.32 (s, 1H), 6.31 (s, 2H), 3.87
(s, 6H), 3.66 (s, 6H), 3.61 (s, 6H); 13C NMR (50 MHz, CDCl3) 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, 40.2.10a,b
12j: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.42 (d, J =
8.2 Hz, 2H), 7.12 (d, J = 8.2 Hz, 2H), 5.88-5.87 (m, 4H), 5.29 (s,
1H), 2.24 (s, 6H); 13C NMR (100 Hz, CDCl3) δ 152.1, 151.6,
139.0, 131.5, 130.1, 120.8, 108.3, 106.1, 44.5, 13.5; HRMS-FAB
(m/z) [M þ H]þ calcd for C17H15BrO2 331.0334, found
331.0331.
10i: white solid; mp 141 °C; 1H NMR (400 MHz, CDCl3) δ
7.51 (d, J = 8.5 Hz, 2H), 7.14 (d, J = 8.5 Hz, 2H), 6.54 (s, 2H),
6.36 (s, 2H), 6.06 (s, 1H), 3.88 (s, 3H), 3.65 (s, 6H), 3.63 (s, 6H);
13C NMR (100 MHz, CDCl3) δ 151.5, 150.6, 148.5, 142.7, 131.7,
129.5, 122.4, 119.2, 114.4, 109.4, 98.0, 56.7, 56.6, 56.0, 43.0;
HRMS-EI (m/z) [M]þ calcd for C26H27NO6 449.1838, found
449.1841.
12k: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.26-7.14
(m, 3H), 7.16-7.14 (m, 1H), 5.91-5.90 (m, 4H), 5.31 (s, 1H),
2.25 (s, 6H); 13C NMR (100 Hz, CDCl3) δ 151.9, 151.7, 142.0,
134.2, 129.6, 128.5, 127.1, 126.6, 108.4, 106.1, 44.7, 13.5;
HRMS-FAB (m/z) [M]þ calcd for C17H15ClO2 286.0761, found
286.0763.
10j: white solid; mp 139-140 °C; 1H NMR (400 MHz,
CDCl3) δ 7.46 (d, J = 8.5 Hz, 1H), 7.33-7.29 (m, 3H), 6.54
(s, 2H), 6.36 (s, 2H), 6.04 (s, 1H), 3.90 (s, 6H), 3.67 (s, 3H), 3.64
(s, 6H); 13C NMR (100 MHz, CDCl3) δ 151.7, 148.8, 146.5,
143.0, 133.7, 132.5, 129.8, 128.8, 122.7, 199.5, 114.7, 112.1, 98.3,
56.9, 56.8, 56.3, 42.7; HRMS-EI (m/z) [M]þ calcd for C26H27-
NO6 449.1838, found 449.1840.
12l: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.54 (d, J =
8.5 Hz, 1H), 7.53 (d, J= 1.5 Hz, 1H), 7.50 (d, J= 8.5 Hz, 1H), 7.41
(d, J = 8.5 Hz, 1H), 5.92-5.91 (m, 4H), 5.36 (s, 1H), 2.24 (s, 6H);
13C NMR (100 Hz, CDCl3) δ 151.9, 151.1, 141.6, 132.9, 131.9,
130.6, 129.1, 118.8, 112.4, 108.7, 106.2, 44.5, 13.5; HRMS-FAB
(m/z) [M]þ calcd for C18H15NO2 277.1103, found 277.1103.
12a: brown solid; mp 141-142 °C; 1H NMR (400 MHz,
CDCl3) δ 7.89 (br s, 2H), 7.40-7.29 (m, 5H), 7.28-7.25 (m, 3H),
7.22-7.14 (m, 3H), 7.02-7.00 (m, 2H), 6.65 (s, 2H), 5.89 (s, 1H);
13C NMR (100 MHz, CDCl3) δ 243.9, 136.7, 128.7, 128.2, 127.0,
126.1, 123.6, 121.9, 119.9, 119.7, 119.2, 111.0, 40.2.8i-l
12b: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.31-7.27
(m, 2H), 7.23 (d, J = 8.5 Hz, 3H), 5.87-5.85 (m, 4H), 5.32 (s,
1H), 2.24 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 152.8, 151.4,
128.4, 128.3, 126.9, 108.1, 106.0, 45.1, 13.6.8b,f,i
1
12m: viscous mass; H NMR (400 MHz, CDCl3) δ 7.60 (d,
J = 8.4 Hz, 2H), 7.35 (d, J = 8.4 Hz, 2H), 5.92-5.91 (m, 4H),
5.38 (s, 1H), 2.24 (s, 6H); 13C NMR (100 Hz, CDCl3) δ 151.9,
151.1, 145.4, 132.2, 129.1, 118.8, 110.8, 108.7, 106.2, 44.9, 13.5;
HRMS-FAB (m/z) [M]þ calcd for C18H15NO2 277.1103, found
277.1102.
12n: viscous mass; 1H NMR (400 MHz, CDCl3) δ 5.96 (d, J =
2.0 Hz, 2H), 5.85 (d, J = 2.0 Hz, 2H), 5.67 (d, J = 7.6 Hz, 1H),
2.30-2.26 (s, 1H), 2.25 (s, 6H), 0.88 (d, J = 7.6 Hz, 6H); 13C
NMR (100 Hz, CDCl3) δ 153.3, 150.3, 106.8, 105.8, 46.3, 31.8,
20.7, 13.5.8e
12c: viscous mass; 1H NMR (400 MHz, CDCl3) δ 7.31-7.22
(m, 5H), 6.59-6.55 (m, 4H), 5.66 (s, 1H), 2.40 (s, 6H); 13C NMR
(100 MHz, CDCl3) δ 145.2, 143.8, 139.0, 128.4, 128.3, 126.9,
125.6, 124.5, 47.6, 15.3.8b
12d: brown solid; mp 187 °C; 1H NMR (400 MHz, CDCl3) δ
7.86 (br s, 2H), 7.40 (d, J = 7.8 Hz, 2H), 7.34 (d, J = 7.8 Hz, 2H),
7.26 (d, J = 8.0 Hz, 2H), 7.18 (t, J = 7.6 Hz, 2H), 7.02 (t, J = 7.6
14a: white solid; mp 123-124 °C; 1H NMR (400 MHz,
CDCl3) δ 7.26-7.21 (m, 2H), 7.17 (d, J = 8.2 Hz, 1H), 7.05
(d, J = 8.4 Hz, 2H), 6.69 (d, J = 8.6 Hz, 2H), 6.46 (d, J = 1.6 Hz,
5248 J. Org. Chem. Vol. 75, No. 15, 2010

Thirupathi and Soo Kim
JOCArticle
2H), 6.37 (dd, J = 8.4, 1.6 Hz, 2H), 6.02 (s, 1H), 3.80 (s, 6H),
3.68 (s, 6H); 13C NMR (100 Hz, CDCl3) δ 159.2, 158.0, 144.6,
130.4, 129.1, 127.8, 125.5, 125.3, 103.5, 98.7, 55.7, 55.2, 42.1.24
14b: white solid; mp109 °C; H NMR (400 MHz, CDCl3) δ
7.04 (d, J = 8.2 Hz, 2H), 6.94 (d, J = 8.2 Hz, 2H), 6.70 (d, J =
8.6 Hz, 2H), 6.45 (d, J = 1.6 Hz, 2H), 6.37 (dd, J = 8.4, 1.6 Hz,
2H), 5.99 (s, 1H), 3.80 (s, 6H), 3.72 (s, 6H); 13C NMR (100 Hz,
CDCl3) δ 159.1, 158.1, 141.4, 134.9, 130.3, 129.0, 128.6, 125.6,
103.5, 98.7, 55.7, 55.2, 41.6, 21.0; HRMS-FAB (m/z) [M]þ calcd
for C24H26O4 378.1831, found 378.1833.
9.0, 1.4 Hz, 2H), 6.07 (s, 1H), 3.80 (s, 6H), 3.69 (s, 6H); 13C NMR
(100 Hz, CDCl3) δ 159.7, 157.9, 146.0, 130.3, 129.6, 123.4, 123.1,
103.7, 98.7, 55.5, 55.2, 42.5; HRMS-FAB (m/z) [M]þ calcd for
C23H23NO6 409.1525, found 409.1527.
1
14f: white solid; mp 97-98 °C; 1H NMR (400 MHz, CDCl3) δ
7.29-7.25 (m, 2H), 7.21-7.19 (m, 1H), 7.10 (d, J = 8.0 Hz, 2H),
7.01 (d, J = 8.8 Hz, 4H), 6.81 (d, J = 8.8 Hz, 4H), 5.44 (s, 1H),
3.78 (s, 6H); 13C NMR (100 Hz, CDCl3) δ 157.9, 144.6, 136.4,
130.2, 129.3, 128.2, 126.1, 113.6, 55.2, 55.1.7,8f
15: white solid, mp 184-185 °C; 1H NMR (400 MHz, CDCl3)
δ 7.51 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.8 Hz, 2H), 7.08 (d, J =
8.0 Hz, 2H), 7.07 (d, J = 8.0 Hz, 2H), 6.80 (d, J = 8.0 Hz, 1H),
6.28 (dd, J = 8.0, 2.0 Hz, 1H), 6.23 (d, J = 2.0 Hz, 1H), 5.67 (d,
J = 9.2 Hz, 1H), 5.51 (d, J = 9.0 Hz, 1H), 3.75 (s, 3H), 3.56 (s,
3H), 2.34 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.9, 160.8,
157.2, 142.8, 140.0, 137.4, 131.1,130.1, 129.1, 128.5, 127.0,
120.9, 119.7, 104.1, 99.1, 58.1, 55.3, 21.4; HRMS-FAB (m/z)
[M]þ calcd for C22H22O4NBrS 475.0453, found 475.0454.
14c: white solid; mp 153-154 °C; 1H NMR (400 MHz,
CDCl3) δ 7.21 (d, J = 8.2 Hz, 2H), 6.99 (d, J = 8.2 Hz, 2H),
6.68 (d, J = 8.6 Hz, 2H), 6.48 (d, J = 1.6 Hz, 2H), 6.39 (dd, J =
8.4, 1.6 Hz, 2H), 5.99 (s, 1H), 3.79 (s, 6H), 3.69 (s, 6H); 13C NMR
(100 Hz, CDCl3) δ 159.4., 158.0, 143.3, 131.2, 130.4, 130.3,
127.9, 124.7, 103.6, 98.7, 55.6, 55.2, 41.7; HRMS-FAB (m/z)
[M]þ calcd for C23H23ClO4 398.1285, found 398.1285.
14d: white solid; mp 105 °C; 1H NMR (400 MHz, CDCl3) δ
7.18-7.14 (m, 2H), 7.05 (s, 1H), 6.96-6.94 (m, H), 6.70 (d, J =
8.6 Hz, 2H), 6.48 (d, J = 1.6 Hz, 2H), 6.40 (dd, J = 8.4, 1.6 Hz,
2H), 6.01 (s, 1H), 3.82 (s, 6H), 3.76 (s, 6H); 13C NMR (100 Hz,
CDCl3) δ 159.4, 157.9, 147.0, 133.7, 130.3, 129.1, 127.3, 125.8,
124.4, 103.6, 98.7, 55.6, 55.2, 41.9; HRMS-FAB (m/z) [M]þ
calcd for C23H23ClO4 398.1285, found 398.1289.
Acknowledgment. The authors thank the Centre for Bio-
logical Modulators of the KRICT for financial support. We
also acknowledge the assistance by BK21 provided by the
Korea Research Council.
14e: white solid; mp 151-152 °C; 1H NMR (400 MHz,
CDCl3) δ 7.09 (d, J = 8.8 Hz, 2H), 7.20 (d, J = 8.0 Hz, 2H),
6.65 (d, J = 9.1 Hz, 2H), 6.48 (d, J = 1.4 Hz, 2H), 6.39 (dd, J =
Supporting Information Available: Experimental procedure
and characterization data of all compounds. This material is
available free of charge via the Internet at http://pubs.acs.org.
J. Org. Chem. Vol. 75, No. 15, 2010 5249