Palladium-catalyzed intramolecular sulfonamidation/oxidation of imines: Access to multifunctional benzimidazoles

Article abstract of DOI:10.1002/adsc.201100370

O-Sulfonamidophenylimines undergo intramolecular sulfonamidation/oxidation to produce 1,2-disubstituted benzimidazoles upon treatment with palladium(II) chloride/(diacetoxyiodo)benzene and potassium carbonate at room temperature. The substituent scope at

Full text of DOI:10.1002/adsc.201100370

FULL PAPERS
DOI: 10.1002/adsc.201100370
Palladium-Catalyzed Intramolecular Sulfonamidation/Oxidation
of Imines: Access to Multifunctional Benzimidazoles
Shaomin Fu,a Huanfeng Jiang,a Yuanfu Deng,a and Wei Zenga,*
a
School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe
District, Guangzhou 510641, Peopleꢀs Republic of China
Fax : (+86)-020-2223-6337; phone: (+86)-020-1357-0415-118; e-mail: zengwei@scut.edu.cn
Received: May 10, 2011; Published online: October 10, 2011
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adcs.201100370.
Abstract: O-Sulfonamidophenylimines undergo in- zole can be extended to alkyl, aryl, alkenyl, acyl, and
tramolecular sulfonamidation/oxidation to produce ester functional groups under mild conditions.
1,2-disubstituted benzimidazoles upon treatment
with palladium(II) chloride/(diacetoxyiodo)benzene
and potassium carbonate at room temperature. The Keywords: C-acylimines; multifunctional benzimida-
substituent scope at the 2-position of the benzimida- zoles; oxidation; palladium; sulfonamidation
Introduction
an efficient access to b-amido carbonyl units,[6] and
Antilla’s group achieved further progress on the
1,2-Disubstituted multifunctional benzimidazoles are Brønsted acid-catalyzed intermolecular amidation of
an important class of heterocyclic building blocks imines to afford N,N-aminals.[7] In the light of these
which are found in various biologically active com- findings, we envisioned that a suitable transition
pounds.[1] One of the most popular methods for benz- metal could activate an imine via interaction of the
ACHTUNGTRENNUNGimidazole synthesis involves the condensation of suit- imine nitrogen and metal ion, the attack of amide nu-
ably substituted 1, 2-diaminoarenes with carboxylic cleophiles to the imine carbon could then result in the
acids or various carboxyl equivalents.[2] Unsubstituted formation of N,N-aminal intermediates, and that a
benzimidazoles can also be directly acylated with subsequent oxidation-dehydrogenation would lead to
esters, lactones, and lactams to form 2-substituted de- the assembly of 1,2-substituted benzimidaoles
rivatives via lithiation under harsh reaction condi- (Scheme 1). To the best of our knowledge, no exam-
tions.[3] Recently, Batey, Ma and Buchwald et al. have ples of transition metal-catalyzed sulfonamidation of
also developed successively transition metal-catalyzed imines have been reported, and the further prepara-
intramolecular aryl guanidinylation or intermolecular tion of 2-acylbenzimidazoles via this type of addition
cascade aryl amination/condensation reactions, which was also previously unknown.
provided an alternative access to 2-amino- or 2-alkyl-
benzimidazoles.[4] Furthermore, Wang and co-workers
found CuI could also efficiently catalyze a three-com- Results and Discussion
ponent cascade reaction of p-tolylsulfonyl azides, al-
kynes and 2-bromoaniline to produce 2-alkyl-1-arene- With this idea in mind, at first we employed C-acyl-
sulfonylbenzimidazoles.[5] However, despite these ef-
ACHTUNGTRENiNGNU mines 1a and 1b as model substrate, our initial inves-
forts, the drawback of the above-mentioned ap- tigation was focused on the effect of substrate type,
proaches is the limited diversity of the substituent transition metal salts and oxidants on the intramolec-
group at the 2-position of benzimidazole, hence a con- ular sulfonamidation/oxidation of C-acylimines, the
cise strategy for constructing diversely 2-substituted results are summarized in Table 1. When (2-benzoyl-
benzimidazole under mild conditions remains a chal-
lenging issue.
ACHTUNGTRENNUNG
On the other hand, catalytic addition of amides nu-
ACHTUNGTRENNUNG
cleophiles to enones (aza-Michael addition) provided toluene (2.0 mL) at 608C for 16 h in the absence of
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Scheme 1. The catalytic amidation of imines.
Table 1. Optimization of reaction conditions for transition
metal-catalyzed intramolecular sulfonamidation/oxidation of
C-acylimines.[a]
any catalyst, no desired product was detected by TLC
and H NMR methods (entry 1). Gratifyingly, when
different transition metal salts were tested for this
1
transformation, we quickly found that CuACTHNURGTNEUNG(OAc)2 pro-
vided a 41% yield of the desired product 2a (entry 2),
and no significantly improved yields of 2a (46–57%)
were obtained when Cu
Cu(OAc)2/rac-BINAP catalyst system was employed
(entries 3 and 4). Unfortunately, if Pd(OAc)2 catalyst
ACHUTNGTNERNUG(OAc)2/PhIACHTUNGTERN(NUGN OAc)2 or
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
was used, only trace amounts of benzimidazole 2a
was observed because of possible sensitivity to the
electron density or coordinating ability of nitrogen
(entry 5). Subsequently, we changed substrate 1a to
[2-(toluene-4-sulfonylamino)-phenylimino]acetic acid
Entry Tether M2+ (equiv.)
Oxidant
(2 equiv.)
Yield
[%][b]
1
2
3
4
5
6
7
8
9
X=CO
–
PhI
–
A
0
41
40
ethyl ester 1b, as compared with Cu
ACHTUNGRTEN(NUNG OTf)2 catalyst
X=CO Cu
X=CO Cu
X=CO Cu
X=CO Pd
X=SO2 Cu
X=SO2 Pd(OAc)2 (0.1)
X=SO2 Pd
G
E
N
(entry 6, 32% yield), Pd(OAc)2 gave a better yield of
AHCTUNGTRENNUNG
PhI
–
A
the desired product 2b (44% yield) in the absence of
oxidant at room temperature for 16 h. Then improved
57[c]
trace[d]
32
ACHTUNGTRENNUNG(OAc)2 (0.1) PhIACTHUNGTRENNNUG
yields (49–56%) were observed when Pd
ACHTUNGERTN(NUNG OAc)2,
A
–
–
PdCl2A(CH3CN)2 or PdCl2 was used as the catalyst for
CTHUNGTRENNUNG
T
E
44
52
49
this transformation in the presence of AgOAc as oxi-
dant under an argon atmosphere in a sealed tube (en-
tries 7–10). Among them, PdCl2 showed the best cata-
lytic activity (entry 10).
With these encouraging results in hand, we futher
investigated systematically the effect of other reaction
conditions including solvents, temperatures, bases and
reaction time on the PdCl2-catalyzed intramolecular
sulfonamidation/oxidantion of C-acylimine 1b. We
(OAc)2 (0.1) AgOAc
X=SO2 PdCl
R
(0.1)
10
11
12
13
14
15
X=SO2 PdCl2 (0.1)
X=SO2 PdCl2 (0.1)
X=SO2 PdCl2 (0.1)
X=SO2 PdCl2 (0.1)
X=SO2 PdCl2 (0.1)
X=SO2 PdCl2 (0.1)
AgOAc
AHCUTNRTGEGUN(NN C6H5CO)2O2 55
PhIO
Ag2CO3
56
17
84
93
30
PhI
O2
ACHTUNGERTN(NUNG OAc)2
[a]
Reaction conditions: for Cu(II)-catalyzed sulfonamida- found the non-polar solvent toluene was superior to
tions of C-acylimines – all the reactions were carried out
in sealed tubes at 608C under an argon atmosphere in
2.0 mL of dry toluene on a 0.1-mmol scale with K2CO3
(0.2 mmol) as base; for Pd(II)-catalyzed sulfonamida-
tions of C-acylimines – all the reactions were carried out
at room temperature under an argon atmosphere in
2.0 mL of dry toluene in sealed tubes on a 0.1-mmol
scale with K2CO3 (0.2 mmol) as base.
CHCl3, CH3CN and dioxane, etc. Among the
screened bases including Cs2CO3, Na2CO3, K2CO3 and
Et3N etc., K2CO3 showed the best activity. The reac-
tion proceeded slowly at lower temperature (ꢀ108C)
while the reaction yield decreased to some degree
possibly due to the decomposition of 1b at higher
temperatures (ꢁ458C). After we had tried different
reaction temperatures, we found room temperature
(258C) was the better choice. Moreover, a longer re-
action time of 16 h is essential to achieve high yields
[b]
[c]
[d]
Isolated yields.
20 mol% of ligand BINAP was used.
Room temperature and 608C were tried, respectively.
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Palladium-Catalyzed Intramolecular Sulfonamidation/Oxidation of Imines
Table 2. Scope of the palladium-catalyzed intramolecular sulfonamidation/oxidation of imines.[a]
Entry
1
Substrate
Product
Yield [%][b]
93
2
71
3
4
5
6
7
8
73
87
92
61
75
58
9
65
83
10
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Table 2. (Continued)
Entry
Substrate
Product
Yield [%][b]
11
12
73
72
78
13
14
71
0
15
[a]
Reaction conditions: all the reactions were carried out at room temperature under an argon atmosphere with substrate
(0.1 mmol), PdCl2 (0.01 mmol), K2CO3 (0.2 mmol), PhIACTHNUTRGNE(NUG OAc)2 (0.2 mmol) and toluene (2.0 mL) at room temperature for
16 h.
Isolated yields.
[b]
(see Supporting Information for complete details). Fi- of C-aryl-, C-alkyl- or C-alkenylimines with sulfona-
nally, the yields from PdCl2 catalyst could be further mide groups to form 2-alkyl-, 2-alkenyl- or 2-arylben-
improved by employing various oxidants such as zimidazoles in good yields ( entries 11–14). We also
Ag2CO3, (C6H5CO)2O2, O2 and PhIACTHNUTRGEN(UNG OAc)2 under the tried to use a Pd(II) or Cu(II) system to catalyze the
optimal reaction conditions (entries 10–15), and the cyclization of 2, 2-dimethyl-3-[toluene-4-sulfonylami-
best yield (93%) of 2b was obtained using the PdCl2/ no)-propylimino]acetic acid ethyl ester (1p), unfortu-
PhI
G
nately, no desired cyclic product 2p was observed
Having established the optimal reaction conditions, (entry 15). The structures of 2j and 2m were unambig-
we turned our attention to the substrate scope and uously assigned by their single crystal X-ray analysis
limitations of this transformation. As shown in (see Supporting Information for more details).
Table 2, the method can be applied to a wide range of
substrates. Both electron-rich and electron-deficient
functional groups such as methyl, methoxy, chloro,
nitro, benzoyl and ethoxycarbonyl are well tolerated
(entries 1–7), they all can provided good to excellent
yields (61–93%), and no significant differences from
substituent electronic effect were observed. The reac-
tion also proceeded smoothly when the C-esteryl
imine was switched to C-acylimines, and moderate
yields could be achieved (entries 8 and 9). It is note-
worthy that the Pd(II)/oxidant catalytic system could
also efficiently enhance the sulfonamidation/oxidation nylation of C-esteryl imines.
Scheme 2. Pd-catalyzed sulfonamidation/oxidation/desulfo-
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Palladium-Catalyzed Intramolecular Sulfonamidation/Oxidation of Imines
molecular sieves or sodium and distilled prior to use. Purifi-
cations of reaction products were carried out by flash chro-
matography using silica gel (40–63 mm). Infrared spectra
were recorded by preparing a KBr pellet containing the title
1
13
compound. H NMR, C NMR spectra were recorded on a
400 MHz spectrometer. Chemical shifts are reported in parts
per million (ppm, d) downfield from residual solvent peaks
and coupling constants are reported as Hertz (Hz). Splitting
patterns are designated as singlet (s), broad singlet (bs),
doublet (d), triplet (t). Splitting patterns that could not be
interpreted or easily visualized are designated as multiplet
(m). Mass spectra were acquired on a quadrupole MS in-
strument in the ESI (+) mode for low resolution spectra
and in the ESI (+) or ESI (À) mode for high resolution
analysis, respectively. Crystal data were collected by employ-
ing graphite monochromated Mo-Ka radiation (l=
0.71073 ꢂ) at 173(2) K and operating in the f-w scan mode.
The structure was solved by direct methods with SHELXS-
97.
Scheme 3. Possible reaction mechanism.
Interestingly, during the course of our work on in-
vestigating the effect of the solvent on the sulfonami-
dation/oxidation of C-ester imines, we found that, as
outlined in Scheme 2, the polar solvent DMF provid-
ed only ethyl 1H-benzo[d]imidazole-2-carboxylate
(3b) instead of 2b via a one-pot cascade sulfonamida-
tion/oxidation/desulfonylation from starting material
1b in 75% yield.
General Procedure for the Synthesis of Amino
Compounds a–j
Sulfonyl choride or carbonyl chloride (10 mmol) in THF
(20 mL) was added dropwise to a solution of diamine
(10 mmol) and pyridine (10 mmol) in THF (20 mL) over a
period of 1 hour at 08C, then the mixture was stirred at
room temperature overnight, the progress of the reaction
was monitored by a TLC method. After starting material
The possible mechanism for this transformation is
outlined in Scheme 3, the first step involves the oxida-
tion of Pd(II) to Pd(IV) in the presence of PhI-
ACHTUNGTRENNUNG(OAc)2, then Pd(IV) coordinates with the imine nitro- had disappeared, the mixture was concentrated to dryness
gen and activates the imine carbon,[8] which further
undergoes an intramolecular necleophile attack by
sulfonamide nitrogen to give intermediate 5, then the
following protonation/oxidation-dehydrogenation af-
fords 1,2-disubstituted benzimidazole 2.
under vacuum, and then water (30 mL) was added to the
residue, and the mixture was extracted with ethyl acetate
(3ꢃ15 mL). The corresponding combined organic layers
were dried over MgSO4. After the solvent had been re-
moved under vacuum, the crude product was purified by
flash chromatography to give desired amino compound with
an amido group.
Conclusions
In summary, we have developed a convenient ap-
proach to multifunctional 1,2-disubstituted benzimda-
zoles using a PdCl2/PhIACTHNUTRGNE(UNG OAc)2 catalyst system under
mild conditions. It is important that this method dis-
plays good functional group tolerance. Furthermore,
the Pd(II)-catalyzed sulfonamidation/oxidation/desul-
fonamidation of imine occurred efficiently in a one-
pot cascade reaction to provide N-unprotected 2-sub-
stituted benzimidazoles in good yields when the polar
solvent DMF is employed. Further synthetic applica-
tions and studies on the mechanism of these transfor-
mations are ongoing in our laboratory.
Experimental Section
General Information
Unless otherwise noted, all experiments were performed
under an argon atmosphere. Solvents were treated with 4 ꢂ
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N-(2-Aminophenyl)-4-methylbenzenesulfonamide
(a):[9]
1H), 7.25 (t, J=4.0 Hz, 1H), 7.32 (d, J=8.0 Hz, 2H), 7.38
(s, 1H), 7.47 (d, J=8.0 Hz, 1H), 7.51 (d, J=8.0 Hz, 1H),
7.64 (d, J=8.0 Hz, 2H), 9.52 (s, 1H); 13C NMR (400 MHz,
DMSO-d6): d=20.9, 108.2, 121.7, 123.3, 124.4, 124.7, 125.8,
126.0, 126.9, 127.2, 129.5, 132.9, 137.1, 141.8, 143.1; MS
(ESI): m/z=313.5 [M+]; HR-MS (EI): m/z=311.0837, calcd.
for [M]À C17H16N2O2S: 311.0854; IR (KBr): n=3395, 3356,
3324, 3269, 3052, 2865, 2610, 2364, 1640, 1606, 1515, 1425,
1396, 1357, 1274, 1114, 872, 739, 479 cmÀ1.
1
Yield: 85%. H NMR (400 MHz, CDCl3): d=2.07 (s, 3H),
3.73 (s, 2H), 6.51 (s, 2H), 6.73 (d, J=8.0 Hz, 2H), 7.02 (t,
J=8.0 Hz, 1H), 7.23 (d, J=7.2 Hz, 2H), 7.62 (d, J=7.2 Hz,
2H), 9.29 (s, 1H); MS (ESI): m/z=263.5 [M+]; IR (KBr):
n=3757, 3646, 3471, 3387, 3208, 3037, 2861, 2801, 2367,
1622, 1500, 1408, 1320, 1147, 1091, 810, 753, 677, 541 cmÀ1.
N-(2-Amino-4-methylphenyl)-4-methylbenzenesulfonam-
1
ide (b): Yield: 76%. H NMR (400 MHz, CDCl3): d=2.17 (s,
N-(2-Aminophenyl)methanesulfonamide (h):[11] Yield:
3H), 2.38 (s, 3H), 4.06 (s, 2H), 6.29 (d, J=7.8 Hz, 1H), 6.35
(d, J=8.0 Hz, 1H), 6.51 (s, 1H), 6.70 (s, 1H), 7.20 (d, J=
7.6 Hz, 2H), 7.60 (d, J=7.6 Hz, 2H); 13C NMR (400 MHz,
CDCl3): d=21.2, 21.6, 117.6, 118.6, 119.5, 127.6, 128.6, 129.6,
136.2, 139.0, 143.7, 144.4; MS (ESI): m/z=277.1 [M+]; HR-
MS (EI): m/z=277.0988, calcd. for [M]+ C14H16N2O2S:
277.1005; IR (KBr): n=3685, 3452, 3281, 3192, 3068, 2921,
2860, 1726, 1597, 1510, 1444, 1377, 1322, 1215, 1157, 1089,
1021, 949, 894, 872, 814, 789, 724, 678, 596 cmÀ1.
1
81%. H NMR (400 MHz, CDCl3): d=3.02 (s, 3H), 4.20 (s,
2H), 6.53 (s, 1H), 6.77 (t, J=8.8 Hz, 2H), 7.11 (s, 2H); MS
(ESI): m/z=187.0 [M+]; IR (KBr): n=3467, 3384, 3243,
1631, 1503, 1467, 1323, 1213, 1141, 973, 763, 508 cmÀ1.
N-(3-Amino-2,2-dimethylpropyl)-4-methylbenzenesulfon-
amide (i): H NMR (400 MHz, CDCl3): d=0.87 (s, 6H), 2.42
1
N
(s, 3H), 2.56 (s, 2H), 2.79 (s, 2H), 7.30 (d, J=7.6 Hz, 2H),
7.74 (d, J=7.6 Hz, 2H); 13C NMR (400 MHz, CDCl3): d=
21.5, 23.6, 34.3, 51.9, 53.1, 127.0, 129.6, 137.3, 142.9; MS
(ESI): m/z=257.2 [M+]; HR-MS (EI): m/z=257.1306, calcd.
for [M+] C12H21N2O2S 257.1318; IR (KBr): n=3501, 3350,
3301, 3043, 2966, 2905, 2860, 1604, 1476, 1359, 1311, 1285,
1152, 1079, 1048, 994, 848, 812, 660, 568, 551 cmÀ1.
N-(2-Amino-4-methoxyphenyl)-4-methylbenzenesulfon-
1
amide (c): Yield: 83%. H NMR (400 MHz, CDCl3): d=2.40
(s, 3H), 3.68 (s, 3H), 4.12 (s, 2H), 6.03 (q, J=8.4 Hz, 1H),
6.24 (d, J=2.4 Hz, 1H), 6.32 (d, J=8.4 Hz, 1H), 6.48 (s,
1H), 7.23 (d, J=8.4 Hz, 2H), 7.61 (d, J=8.4 Hz, 2H);
13C NMR (400 MHz, CDCl3): d=21.6, 55.2, 101.5, 104.3,
113.9, 127.6, 129.6, 130.2, 136.0, 143.8, 146.4, 160.2; MS
(ESI): m/z=315.1 [M+Na+]; HR-MS (EI): m/z=293.0924,
calcd. for [M]+ C14H16N2O3S: 293.0954; IR (KBr): n=3687,
3257, 3118, 2839, 2361, 1711, 1596, 1511, 1322, 1220, 1158,
1096, 1022, 893, 815, 683, 538 cmÀ1.
N-(2-Aminophenyl)benzamide (j):[12] 1H NMR (400 MHz,
CDCl3): d=3.88 (s, 2H), 6.83 (m, 2H), 7.09 (m, 1H), 7.32
(d, J=8.4 Hz, 1H), 7.47 (t, J=7.2 Hz, 2H), 7.55 (t, J=
7.2 Hz, 1H), 7.89 (d, J=8.0 Hz, 3H); MS (ESI): m/z=213.5
[M+]; IR (KBr): n=3696, 3400, 3271, 3058, 1643, 1601, 1578,
1529, 1450, 1315, 1026, 910, 750, 711 cmÀ1.
N-(2-Amino-5-chlorophenyl)-4-methylbenzenesulfon-
1
N
General Procedure for the Synthesis of Imines 1a–1p
2.41 (s, 3H), 4.21 (s, 2H), 6.38 (d, J=8.0 Hz, 1H), 6.45 (d,
J=8.0 Hz, 1H), 6.67 (s, 1H), 6.69 (d, J=2.0 Hz, 1H), 7.25
(d, J=9.2 Hz, 2H), 7.62 (d, J=8.4 Hz, 2H); MS (ESI):
m/z=297.0 [M+]; IR (KBr): n=3475, 3382, 3258, 3067, 2921,
1911, 1622, 1498, 1437, 1390, 1334, 1214, 1165, 1090, 887,
854, 812, 722, 700, 672, 560 cmÀ1.
Ethyl glyoxylate (4.0 mmol) in 5.0 mL dry toluene was
added dropwise to a mixture of anhydrous sodium sulfate
(10.0 mmol)
and
N-(2-aminophenyl)-sulfonamide
(4.0 mmol) in toluene (15 mL) at room temperature. Then
the mixture was stirred at room temperature for 24 h, the
progress of the reaction was monitored by a TLC method.
After the starting material had disappeared, the Na2SO4 was
filtered off, and the filtrate was concentrated under vacuum.
The crude material was purified by flash chromatography to
give desired product.
Ethyl 2-(2-benzamidophenylimino)acetate (1a): Yield:
68%. 1H NMR (400 MHz, CDCl3): d=1.45 (t, J=7.2 Hz,
3H), 4.41 (q, J=7.2 Hz, 2H), 7.13 (t, J=7.6 Hz, 1H), 7.33
(d, J=8.4 Hz, 1H), 7.46 (t, J=8.0 Hz, 1H), 7.51 (t, J=
7.2 Hz, 2H), 7.57 (t, J=7.2 Hz, 1H), 8.00 (d, J=7.6 Hz,
2H), 8.07 (s, 1H), 8.74 (d, J=8.0 Hz, 1H), 9.78 (s 1H);
13C NMR (400 MHz, CDCl3): d=14.2, 62.0, 116.1, 120.0,
123.6, 127.1, 128.8, 131.6, 132.0, 134.6, 134.7, 135.9, 147.3,
163.1, 164.8; MS (ESI): m/z=297.1 [M+]; HR-MS (EI):
m/z=295.1085, calcd. for [M]À C17H16N2O3: 295.1083; IR
(KBr): n=3653, 3466, 3067, 2929, 2848, 2364, 1742, 1618,
1526, 1378, 1198, 1044, 812, 668, 590, 546 cmÀ1.
N-(2-Amino-5-nitrophenyl)-4-methylbenzenesulfonamide
1
(e): Yield: 78%. H NMR (400 MHz, DMSO-d6): d=2.36 (s,
3H), 6.48 (s, 2H), 6.67 (d, J=9.2 Hz, 1H), 7.37 (d, J=
8.4 Hz, 2H), 7.59 (t, J=7.6 Hz, 3H), 7.82 (q, J=9.2 Hz,
1H), 9.50 (s, 1H); 13C NMR (400 MHz, CDCl3): d=21.0,
113.8, 119.3, 122.8, 124.1, 126.9, 129.6, 135.3, 136.4, 143.5,
150.9; MS (ESI): m/z=305.9 [MÀ]; HR-MS (EI): m/z=
308.0677, calcd. for [M]+ C13H13N3O4S: 308.0700; IR (KBr):
n=3689, 3479, 3369, 3094, 1708, 1583, 1519, 1491, 1304,
1160, 1094, 967, 918, 817, 748, 674, 542 cmÀ1.
Ethyl
4-amino-3-(4-methylphenylsulfonamido)benzoate
1
(f): Yield: 79%. H NMR (400 MHz, DMSO-d6): d=1.21 (t,
J=7.2 Hz, 2H), 2.36 (s, 3H), 4.14 (q, J=7.2 Hz, 2H), 5.76
(d, J=5.6 Hz, 2H), 6.64 (d, J=8.4 Hz, 1H), 7.30 (s 1H),
7.34 (d, J=8.0 Hz, 2H), 7.48 (d, J=8.0 Hz, 1H), 7.58 (d, J=
8.4 Hz, 2H), 9.27 (s, 1H); 13C NMR (400 MHz, DMSO-d6):
d=14.2, 20.9, 59.6, 114.2, 116.4, 119.6, 126.9, 128.7, 129.0,
129.5, 137.0, 143.0, 149.0, 165.2; MS (ESI): m/z=335.1 [M+];
HR-MS (EI): m/z=335.1036, calcd. for [M]+ C16H18N2O4S:
335.1060; IR (KBr): n=3700, 3475, 3371, 3135, 2988, 2910,
2833, 2782, 2714, 1681, 1616, 1581, 1390, 1302, 1206, 1157,
1016, 772, 728, 563 cmÀ1.
Ethyl 2-[2-(4-methylphenylsulfonamido)phenylimino]ace-
1
tate (1b): Yield: 62%. H NMR (400 MHz, CDCl3): d=1.29
(t, J=7.2 Hz, 3H), 2.31 (s, 3H), 4.24 (q, J=4.8 Hz, 2H),
4.81 (s, 1H), 5.66 (s, 1H), 6.57 (d, J=7.6 Hz, 1H), 6.81 (t,
J=7.6 Hz, 1H), 6.92 (t, J=7.6 Hz, 1H), 7.14 (d, J=8.0 Hz,
2H), 7.46 (d, J=7.6 Hz, 1H), 7.53 (d, J=8.8 Hz, 2H);
13C NMR (400 MHz, CDCl3): d=21.6, 35.7, 113.7, 120.1,
124.7, 124.9, 126.9, 127.0, 128.6, 129.2, 129.9, 133.0, 135.1,
N-(3-Aminonaphthalen-2-yl)-4-methylbenzenesulfonam-
ACHTUNGTRENNUNG
ide (g): Yield: 69%. 1H NMR (400 MHz, DMSO-d6): d=
2.34 (s, 3H), 5.24 (s, 2H), 6.91 (s, 1H), 7.07 (t, J=4.0 Hz,
2800
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ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 2795 – 2804

Palladium-Catalyzed Intramolecular Sulfonamidation/Oxidation of Imines
CDCl3): d=1.32(t, J=7.6 Hz, 3H), 2.37 (s, 3H), 4.27 (q, J=
7.2 Hz, 2H), 4.58 (s, 1H), 5.64 (s, 1H), 6.54 (d, J=2.0 Hz,
1H), 6.79 (q, J=8.0 Hz, 2H), 7.19 (d, J=8.0 Hz, 2H), 7.37
(d, J=8.4 Hz, 2H), 7.54 (d, J=8.4 Hz, 2H); 13C NMR
(400 MHz, CDCl3): d=14.1, 21.6, 63.0, 75.5, 111.2, 118.1,
120.5, 127.5, 128.9, 129.8, 131.7, 133.4, 142.8, 144.9, 169.3;
MS
(ESI):
m/z=381.2
[M+];
HR-MS
(EI):
m/z=381.0633, calcd. for [M]+ C17H18N2O4S: 381.0670; IR
(KBr): n=3696, 3314, 3083, 1745, 1583, 1492, 1365, 1215,
1163, 670, 594, 543 cmÀ1.
Ethyl
2-[2-(4-methylphenylsulfonamido)-4-nitrophenyl-
AHCTUNGTRENNUNG
CDCl3): d=1.33 (t, J=7.2 Hz, 3H), 2.39 (s, 3H), 4.29 (q, J=
7.2 Hz, 2H), 5.29 (s, 1H), 5.86 (s, 1H), 6.56 (d, J=8.4 Hz,
1H), 7.24 (d, J=8.4 Hz, 2H), 7.63 (d, J=8.4 Hz, 2H), 7.92
(q, J=8.4 Hz, 1H), 8.23 (s, J=4.0 Hz, 1H); 13C NMR
(400 MHz, CDCl3): d=14.0, 21.6, 63.2, 75.8, 108.0, 112.2,
123.9, 127.5, 130.0, 130.4, 133.3, 141.1, 145.5, 147.0, 168.2;
MS (ESI): m/z=392.0 [M+]; HR-MS (EI): m/z=392.0872,
calcd. for [M]+ C17H17N3O6S: 392.0911; IR (KBr): n=3297,
3114, 2979, 1736, 1604, 1497, 1461, 1366, 1329, 1284, 1220,
1163, 1075, 986, 894, 821, 746, 670, 588, 540 cmÀ1.
Ethyl 2-[3-(4-methylphenylsulfonamido)naphthalen-2-yl-
AHCTUNGTRENNUNG
imino]acetate (1h): Yield: 61%. 1H NMR (400 MHz,
CDCl3): d=1.32 (t, J=7.2 Hz, 3H), 2.31 (s, 3H), 4.27 (q, J=
8.0 Hz, 2H), 4.70 (s, 1H), 5.72 (s, 1H), 6.84 (s, 1H), 7.14 (d,
J=8.0 Hz, 2H), 7.31 (m, 2H), 7.52 (d, J=7.6 Hz, 1H), 7.61
(d, J=8.0 Hz, 2H), 7.73 (d, J=8.0 Hz, 1H), 7.85 (s, 1H);
13C NMR (400 MHz, CDCl3): d=14.1, 21.6, 62.9, 75.1, 105.4,
113.9, 123.8, 125.7, 126.2, 127.4, 128.0, 129.5, 129.8, 131.1,
132.7, 134.0, 140.2, 144.8, 169.3; MS (ESI): m/z=397.2 [M+];
HR-MS (EI): m/z=395.1065, calcd. for [M]À C21H20N2O4S:
395.1066; IR (KBr): n=3622, 3355, 3261, 3056, 2975, 2926,
2863, 2362, 1736, 1631, 1598, 1470, 1365, 1312, 1161, 1088,
1023, 865, 811, 749, 669, 592, 547 cmÀ1.
Ethyl 2-[2-(methylsulfonamido)phenylimino]acetate (1k):
Yield: 70%. 1H NMR (400 MHz, CDCl3): d=1.30 (t, J=
7.2 Hz, 3H), 2.92 (s, 3H), 4.26 (q, J=7.2 Hz, 2H), 4.88 (s,
1H), 5.74 (s, 1H), 6.79 (d, J=7.6 Hz, 1H), 6.84 (t, J=
7.6 Hz, 1H), 7.02 (t, J=7.6 Hz, 1H), 7.27 (t, J=7.2 Hz, 1H);
13C NMR (400 MHz, CDCl3): d=14.0, 36.9, 62.8, 75.3, 111.4,
116.3, 121.1, 126.2, 130.1, 141.1, 163.5; MS (ESI): m/z=271.1
[M+]; HR-MS (EI): m/z=293.0568, calcd. for [M+Na]+
C11H14N2O4S: 293.0572; IR (KBr): n=3653, 3466, 3067,
2929, 2848, 2364, 1742, 1618, 1526, 1378, 1198, 1044, 812,
668, 590, 546 cmÀ1.
Ethyl 2-[2,2-dimethyl-3-(4-methylphenylsulfonamido)pro-
pylimino]acetate (1p): Yield: 55%. 1H NMR (400 MHz,
CDCl3): d=0.84 (s, 3H), 1.03 (s, 3H), 1.17 (t, J=8.0 Hz,
3H), 2.41 (s, 3H), 2.47 (d, J=12.0 Hz, 1H), 2.60 (d, J=
12.0 Hz, 1H), 3.12 (d, J=12.0 Hz, 1H), 3.33 (d, J=16.0 Hz,
1H), 5.28 (s, 1H), 7.17 (t, J=4.0 Hz, 1H), 7.27 (d, J=
8.0 Hz, 2H), 7.66 (d, J=8.0 Hz, 2H); 13C NMR (400 MHz,
CDCl3): d=14.0, 21.5, 22.6, 25.3, 29.5, 52.2, 52.6, 61.6, 67.4,
127.2, 129.4, 136.9, 143.2, 168.2; MS (ESI): m/z=341.2 [M+];
HR-MS (EI): m/z=341.1530, calcd. for [M]À C16H24N2O4S:
341.1535; IR (KBr): n=3352, 2958, 2871, 2363, 1740, 1599,
1467, 1342, 1234, 1160, 1093, 1023, 981, 916, 896, 815, 773,
707, 666, 602, 546 cmÀ1.
136.0, 141.9, 145.6, 153.0; MS (ESI): m/z=347.1 [M+]; HR-
MS (EI): m/z=345.0915, calcd. for [M]À C17H18N2O4S:
345.0909; IR (KBr): n=3361, 3060, 2979, 2360, 1743, 1600,
1484, 1360, 1210, 1165, 1090, 1022, 811, 744, 674, 577,
540 cmÀ1.
Ethyl 2-[5-methyl-2-(4-methylphenylsulfonamido)phenyl-
ACHTUNGTRENNUNG
imino]acetate (1c): Yield: 49%. 1H NMR (400 MHz,
CDCl3): d=1.32 (t, J=7.2 Hz, 3H), 2.22 (s, 3H), 2.35 (s,
3H), 4.26 (q, J=5.6 Hz, 2H), 4.40 (s, 1H), 5.59 (s, 1H), 6.42
(s, 1H), 6.64 (d, J=8.0 Hz, 1H), 7.16 (d, J=8.4 Hz, 2H),
7.36 (d, J=8.0 Hz, 1H), 7.52 (d, J=8.4 Hz, 2H);13C NMR
(400 MHz, CDCl3): d=14.1, 21.4, 21.6, 62.8, 75.3, 112.0,
117.4, 121.4, 127.5, 127.8, 129.6, 133.7, 136.6, 141.8, 144.5,
169.8; MS (ESI): m/z=361.1 [M+]; HR-MS (EI): m/z=
359.1072, calcd. for [M]À C18H20N2O4S: 359.1066; IR (KBr):
n=3842, 3346, 3055, 2926, 2356, 1741, 1599, 1504, 1460,
1367, 1324, 1256, 1173, 1027, 812, 675, 589, 551 cmÀ1.
Ethyl 2-[5-methoxy-2-(4-methylphenylsulfonamido)phen-
ACHTUNGTRENNUNG
ylimino]acetate (1d): Yield: 55%. 1H NMR (400 MHz,
CDCl3): d=1.32 (t, J=7.2 Hz, 3H), 2.35 (s, 3H), 3.71 (s,
3H), 4.27 (q, J=6.0 Hz, 2H), 4.45 (s, 1H), 5.57 (s, 1H), 6.17
(s, J=2.0 Hz, 1H), 6.35 (q, J=6.0 Hz, 1H), 7.16 (d, J=
8.0 Hz, 2H), 7.39 (d, J=8.8 Hz, 1H), 7.49 (d, J=8.4 Hz,
2H); 13C NMR (400 MHz, CDCl3): d=14.1, 21.6, 55.6, 62.8,
75.5, 98.1, 105.2, 118.7, 123.4, 127.6, 129.6, 133.4, 143.3,
144.5, 159.1, 169.8; MS (ESI): m/z=377.2 [M+]; HR-MS
(EI): m/z=375.1022, calcd. for [M]À C18H20N2O5S: 375.1015;
IR (KBr): n=3739, 3637, 3272, 2937, 2351, 1740, 1608, 1510,
1328, 1211, 1169, 1087, 1022, 817, 672, 550 cmÀ1.
Notes: Starting material imines 1g, 1i, 1j, 1l, 1m, 1n and
1o could not be isolated, so they were made in situ from the
corresponding amino compounds and aldehydes.[13]
Ethyl 2-[5-chloro-2-(4-methylphenylsulfonamido)phenyl-
ACHTUNGTRENNUNG
imino]acetate (1e): Yield: 68%. 1H NMR (400 MHz,
Adv. Synth. Catal. 2011, 353, 2795 – 2804
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2801

Shaomin Fu et al.
FULL PAPERS
1H), 7.86 (d, J=8.4 Hz, 1H), 8.07 (d, J=8.0 Hz, 2H);
13C NMR (400 MHz, CDCl3): d=14.0, 21.8, 63.6, 114.6,
121.4, 127.4, 128.1, 130.2, 130.7, 131.1, 134.2, 142.4, 144.5,
146.7, 159.6; MS (ESI): m/z=379.4 [M+]; HR-MS (EI):
m/z=379.0468, calcd. for [M]+ C17H15N2O4SCl: 379.0486; IR
(KBr): n=3852, 3760, 3645, 3464, 2979, 2925, 2864, 2361,
1744, 1593, 1437, 1384, 1172, 1044, 803, 770, 668, 594,
464 cmÀ1.
General Procedure for the Synthesis of
Benzimidazoles 2a–2o
To the solution of imine 1 (0.1 mmol) in dry toluene
(2.0 mL) were added PdCl2 (10 mol%), K2CO3 (2.0 equiv.)
and PhIACHTUNGTRENNUNG(OAc)2 (2.0 equiv.) under an argon atmosphere. The
reaction mixture was stirred at 258C for 16 h. Then the mix-
ture was filtered, and the corresponding filtrate was concen-
trated under vacuum and purified by flash chromatography
on silica gel using 20% ethyl acetate in petroleum ether as
eluent to offer the desired compound 2.
Ethyl 6-nitro-1-tosyl-1H-benzo[d]imidazole-2-carboxylate
1
(2f): Yield: 92%. H NMR (400 MHz, CDCl3): d=1.51 (t,
J=7.2 Hz, 3H), 2.45 (s, 3H), 4.60 (q, J=7.2 Hz, 2H), 7.42
(d, J=8.4 Hz, 1H), 7.91 (d, J=8.8 Hz, 1H), 8.14 (d, J=
8.8 Hz, 2H), 8.31 (q, J=8.8 Hz, 1H), 8.90 (d, J=2.4 Hz,
1H); 13C NMR (400 MHz, CDCl3): d=14.0, 21.8, 64.0, 110.5,
120.8, 122.1, 128.5, 130.5, 131.6, 133.6, 145.6, 146.3, 147.3,
147.4, 159.2; MS (ESI): m/z=390.1 [M+]; HR-MS (EI):
m/z=390.0725, calcd. for [M]+ C18H18N2O4S: 390.0754; IR
(KBr): n=3460, 3119, 2979, 1739, 1619, 1535, 1443, 1385,
1326, 1280, 1086, 1040 cmÀ1.
Ethyl
1-benzoyl-1H-benzo[d]imidazole-2-carboxylate
1
(2a): Yield: 57%. H NMR (400 MHz, CDCl3): d=1.24 (t,
J=7.6 Hz, 3H), 4.21 (q, J=7.6 Hz, 2H), 7.43 (t, J=2.0 Hz,
2H), 7.44 (t, J=8.4 Hz, 1H), 7.44 (d, J=7.6 Hz, 2H), 7.52
(t, J=8.0 Hz, 3H), 7.68 (t, J=8.0 Hz, 1H), 7.77 (d, J=
8.0 Hz, 2H), 7.96 (t, J=4.0 Hz, 1H); 13C NMR (400 MHz,
CDCl3): d=13.9, 62.9, 113.1, 122.0, 125.1, 127.1, 129.2, 129.9,
133.4, 134.5, 141.8, 143.5, 159.0, 167.6; MS (ESI): m/z=295.2
[M+]; HR-MS (EI): m/z=317.0888, calcd. for [M+Na]+
C22H18N2O2S: 317.0902; IR (KBr): n=3760, 3646, 3065,
2073, 2926, 2856, 2362, 1720, 1593, 1510, 1444, 1391, 1325,
1278, 1200, 1015, 962, 866, 755, 709 cmÀ1.
Diethyl 3-tosyl-3H-benzo[d]imidazole-2,5-dicarboxylate
1
(2g): Yield: 61%. H NMR (400 MHz, CDCl3): d=1.45 (t,
J=7.6 Hz, 3H), 1.50 (t, J=7.6 Hz, 3H), 4.45 (q, J=7.6 Hz,
2H), 4.58 (q, J=7.6 Hz, 2H), 7.38 (d, J=8.4 Hz,2H), 7.82
(d, J=8.4 Hz, 1H); 8.11 (m, 3H), 8.69 (d, J=0.4 Hz, 1H);
13C NMR (400 MHz, CDCl3): d=14.0, 14.4, 21.8, 61.5, 63.7,
115.6, 121.4, 126.5, 128.3, 129.1, 130.2, 131.8, 134.2, 144.2,
145.6, 146.7, 159.7, 166.0; MS (ESI): m/z=417.2 [M+]; HR-
MS (EI): m/z=417.1086, calcd. for [M]+ C20H20N2O6S:
417.1080; IR (KBr): n=2987, 2907, 2381, 2381, 1745, 1720,
1596, 1518, 1383, 1283, 1185, 1092, 1024, 768, 668, 578,
466 cmÀ1.
Ethyl 1-tosyl-1H-benzo[d]imidazole-2-carboxylate (2b):
Yield: 93%. 1H NMR (400 MHz, CDCl3): d=1.48 (t, J=
7.2 Hz, 3H), 2.42 (s, 3H), 4.56 (q, J=7.2 Hz, 2H), 7.33 (d,
J=7.6 Hz, 2H), 7.40(d, J=7.6 Hz, 1H), 7.48 (t, J=8.4 Hz,
1H), 7.79 (t, J=7.6 Hz, 2H), 7.99 (d, J=8.4 Hz, 1H), 8.09
(d, J=8.4 Hz, 2H); 13C NMR (400 MHz, CDCl3): d=14.0,
21.6, 63.4, 113.6, 121.6, 125.3, 126.9, 128.1, 130.1, 132.0,
134.4, 141.4, 143.4, 146.4, 160.0; MS (ESI): m/z=345.03
[M+]; HR-MS (EI): m/z=345.0894, calcd. for [M]+:
C17H16N2O4S: 345.0917; IR (KBr): n=3692, 2997, 1733,
1596, 1524, 1381, 1370, 1201, 1173, 1086, 1049 cmÀ1.
Ethyl 1-tosyl-1H-naphthoACTHNURTGNEU[GN 2,3-d]imidazole-2-carboxylate
1
(2h): Yield: 75%. H NMR (400 MHz, CDCl3): d=1.51 (t,
J=7.2 Hz, 3H), 2.39 (s, 3H), 4.60 (q, J=7.2 Hz, 2H), 7.33
(d, J=8.4 Hz, 2H), 7.51 (m, 2H), 7.98 (d, J=8.0 Hz, 1H),
8.02 (d, J=12.0 Hz, 1H), 8.12 (d, J=8.0 Hz, 2H), 8.26 (s,
1H), 8.39 (s, 1H); 13C NMR (400 MHz, CDCl3): d=14.0,
21.7, 29.7, 63.6, 125.4, 126.2, 128.0, 128.2, 128.6, 130.1, 131.2,
131.4„ 132.3, 134.5, 141.0, 146.3, 146.4, 160.1; MS (ESI):
m/z=395.2 [M+]; HR-MS (EI): m/z=395.1033, calcd for
[M]+ C21H18N2O4S: 395.1060; IR (KBr): n=3467, 3060, 2927,
2859, 2360, 1744, 1596, 1382, 1317, 1254, 1186, 1127, 1086,
1032, 868, 764, 669, 588, 545 cmÀ1.
Ethyl 5-methyl-1-tosyl-1H-benzo[d]imidazole-2-carboxyl-
1
ate (2c): Yield: 71%. H NMR (400 MHz, CDCl3): d=1.48
(t, J=7.2 Hz, 3H), 2.41 (s, 3H), 2.46 (s, 3H), 4.54 (q, J=
6.8 Hz, 2H), 7.27 (d, J=5.6 Hz, 1H), 7.34 (d, J=8.0 Hz,
2H), 7.57 (s, 1H), 7.86 (d, J=8.4 Hz, 1H), 8.07 (d, J=
8.0 Hz, 2H); 13C NMR (400 MHz, CDCl3): d=14.0, 21.4,
21.7, 63.3, 113.2, 121.4, 128.1, 128.4, 130.0, 130.3, 134.7,
135.4, 141.8, 143.4, 146.2, 160.0; MS (ESI): m/z=359.2 [M+];
HR-MS (EI): m/z=359.1025, calcd. for [M]+ C18H18N2O4S
359.1060; IR (KBr): n=3852, 3760, 3645, 3464, 2979, 2925,
2864, 2361, 1744, 1593, 1437, 1384, 1172, 1044, 803, 770, 668,
594, 464 cmÀ1.
1-(1-Tosyl-1H -benzo[d] imidazol-2-yl) ethanone (2i):
1
Yield: 58%. H NMR (400 MHz, CDCl3): d=2.43 (s, 3H),
3.73 (s, 3H), 2.79 (s, 3H), 7.37 (d, J=8.0 Hz, 2H), 7.43 (t,
J=8.0 Hz, 1H), 7.53 (d, J=8.0 Hz, 1H); 7.82 (d, J=8.0 Hz,
1H), 8.12 (t, J=8.8 Hz, 3H); 13C NMR (400 MHz, CDCl3):
d=21.8, 29.0, 114.4, 113.9, 121.9, 125.3, 127.6, 128.2, 133.9,
135.1, 141.1, 146.0, 148.6, 191.3; MS (ESI): m/z=315.0 [M+];
HR-MS (EI): m/z=313.0643, calcd. for [M]À C16H14N2O3S:
313.0647; IR (KBr): n=3738, 3378, 3055, 2857, 2360, 1701,
1591, 1497, 1441, 1366, 1305, 1181, 1129, 1090, 1029, 972,
899, 816, 752, 676, 569 cmÀ1.
Phenyl (1-tosyl-1H-benzo[d]imidazol-2-yl) methanone
(2j): Yield: 65%. 1H NMR (400 MHz, CDCl3): d=2.41 (s,
1H), 7.37 (d, J=8.0 Hz, 2H), 7.43 (t, J=8.0 Hz, 1H), 7.52
(m, 3H), 7.66 (t, J=8.0 Hz, 1H), 7.82 (d, J=8.0 Hz, 1H),
8.06 (m, 3H), 8.14 (d, J=8.0 Hz, 2H); 13C NMR (400 MHz,
CDCl3):d=21.8, 113.6, 121.7, 125.3, 126.8, 128.3, 128.8,
130.1, 130.7, 132.3, 134.5, 134.7, 135.3, 141.8, 146.4, 148.0,
186.3; MS (ESI): m/z=377.5 [M+]; HR-MS (EI): m/z=
Ethyl 5-methoxy-1-tosyl-1H-benzo[d]imidazole-2-carbox-
1
ylate (2d): Yield: 73%. H NMR (400 MHz, CDCl3): d=1.48
(t, J=7.2 Hz, 3H), 3.41 (s, 3H), 3.84 (s, 3H), 4.54 (q, J=
7.2 Hz, 2H), 7.09 (d, J=9.2 Hz, 1H), 7.22 (d, J=2.0 Hz,
1H), 7.34 (d, J=8.4 Hz, 2H), 7.87 (d, J=8.8 Hz, 1H), 8.06
(d, J=8.0 Hz, 2H); 13C NMR (400 MHz, CDCl3): d=14.0,
21.7, 55.8, 63.3, 103.4, 114.2, 116.9, 126.6, 128.0, 130.0, 134.7,
142.5, 143.7, 146.2, 158.0, 159.8; MS (ESI): m/z=374.9 [M+];
HR-MS (EI): m/z=375.0983, calcd. for [M]+ C18H18N2O5S:
375.1009; IR (KBr): n=3414, 2978, 2934, 2843, 2362, 1743,
1609, 1524, 1498, 1463, 1337, 1216, 1162, 1092, 1029, 813,
670, 551 cmÀ1.
Ethyl 5-chloro-1-tosyl-1H-benzo[d]imidazole-2-carboxyl-
1
ate (2e): Yield: 87%. H NMR (400 MHz, CDCl3): d=1.48
(t, J=7.2 Hz, 3H), 2.42 (s, 3H), 4.56 (q, J=7.2 Hz, 2H),
7.27 (d, J=5.6 Hz, 1H), 7.34 (d, J=8.0 Hz, 2H), 7.57 (s,
2802
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ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 2795 – 2804

Palladium-Catalyzed Intramolecular Sulfonamidation/Oxidation of Imines
375.0814, calcd. for [M]À C21H16N2O3S: 375.0803; IR (KBr):
n=3747, 3671, 3064, 2929, 1740, 1680, 1591, 1616, 1447,
1380, 1326, 1179, 1049, 955, 713, 670, 576 cmÀ1.
7.74 (m, 2H); MS (ESI): m/z=191.3 [M+]; IR (KBr): n=
3849, 3756, 3645, 3387, 3207, 3037, 2862, 2359, 1619, 1500,
1408, 1319, 1147, 1092, 927, 809, 753, 677, 541 cmÀ1.
Ethyl 1-methylsulfonyl-1H-benzo[d]imidazole-2-carboxyl-
1
ate (2k): Yield: 83%. H NMR (400 MHz, CDCl3): d=1.49
Supporting Information
(t, J=7.2 Hz, 3H), 3.73 (s, 3H), 4.55 (q, J=7.6 Hz, 2H),
6.79 (d, J=8.0 Hz, 1H), 6.84 (t, J=8.0 Hz, 1H), 7.02 (t, J=
8.0 Hz, 1H), 7.48 (m, 2H), 7.87 (d, J=8.0 Hz, 1H), 7.97 (d,
J=8.0 Hz, 1H); 13C NMR (400 MHz, CDCl3): d=14.0, 43.4,
63.6, 113.9, 122.1, 125.5, 127.4, 133.2, 140.9, 143.0, 159.7; MS
(ESI): m/z=269.1 [M+]; HR-MS (EI): m/z=267.0449, calcd.
for [M]À C11H12N2O4S: 267.0440; IR (KBr): n=3852, 3760,
3645, 3464, 2979, 2925, 2864, 2361, 1744, 1593, 1437, 1384,
1172, 1044, 803, 770, 668, 594, 464 cmÀ1.
Details of experimental conditions, characterization data, as
1
well as copies of H and 13C NMR spectra for all isolated
compounds are available in the Supporting Information.
CCDC 832623 (2j) and CCDC 832622 (2m) contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_-
request/cif.
2-Methyl-1-tosyl-1H-benzo[d]imidazole
(2l):[5]
Yield:
1
73%. H NMR (400 MHz, CDCl3): d=2.39 (s, 3H), 2.82 (s,
3H), 7.29 (d, J=8.0 Hz, 2H), 7.33 (t, J=7.6 Hz, 2H), 7.63
(d, J=7.6 Hz, 1H); 7.80 (d, J=8.0 Hz, 2H), 8.03 (t, J=
7.2 Hz, 1H); 13C NMR (400 MHz, CDCl3): d=21.8, 29.0,
114.4, 113.9, 121.9, 125.3, 127.6, 128.2, 133.9, 135.1, 141.1,
146.0, 148.6, 191.3; MS (ESI): m/z=287.2 [M+]; IR (KBr):
n=3734, 3106, 3086, 2925, 2853, 2360, 1919, 1597, 1546,
1473, 1373, 1296, 1247, 1173, 1089, 1053, 1016, 914, 771, 749,
703, 690, 665, 578, 544 cmÀ1.
2-Benzyl-1-tosyl-1H-benzo[d]imidazole (2m): Yield: 72%.
1H NMR (400 MHz, CDCl3): d=2.30 (s, 3H), 4.63 (s, 2H),
7.05 (d, J=8.0 Hz, 2H), 7.19 (t, J=8.4 Hz, 1H), 7.26 (m,
1H), 7.34 (m, 3H), 7.70 (d, J=7.6 Hz, 1H), 7.95 (d, J=
8.4 Hz, 1H); 13C NMR (400 MHz, CDCl3): d=21.6, 35.7,
113.7, 120.1, 124.7, 125.0, 126.9, 127.0, 128.6, 129.2, 129.9,
133.0, 135.1, 136.0, 141.9, 145.6, 153.0; MS (ESI): m/z=363.1
[M+]; HR-MS (EI): m/z=361.1012, calcd. for [M]À
C22H18N2O2S: 361.1011; IR (KBr): n=3690, 3063, 3034,
2920, 1718, 1595, 1539, 1493, 1462, 1420, 1379, 1303, 1254,
1229, 1192, 1162, 1122, 1084, 1046, 1011, 813, 768, 747, 718,
678, 663, 582, 541 cmÀ1.
2-Phenyl-1-tosyl-1H-benzo[d] imidazole (2n): Yield: 78%.
1H NMR (400 MHz, CDCl3): d=2.32 (s, 3H), 7.09 (d, J=
8.4 Hz, 2H), 7.33 (d, J=8.0 Hz, 2H), 7.39 (m, 4H), 7.46 (t,
J=8.4 Hz, 1H), 7.55 (t, J=8.0 Hz, 1H), 7.61 (d, J=7.6 Hz,
2H), 7.73 (d, J=8.0 Hz, 1H), 8.21 (d, J=8.0 Hz, 1H);
13C NMR (400 MHz, CDCl3): d=21.6, 115.2, 120.4, 125.3,
125.5, 127.0, 127.7, 129.7, 130.0, 130.6, 130.9, 133.9, 135.0,
142.6, 145.7, 154.1; MS (ESI): m/z=349.2 [M+]; HR-MS
(EI): m/z=347.0862, calcd. for [M]À C20H16N2O2S: 347.0845;
IR (KBr): n=3740, 3681, 3301, 3063, 2922, 2860, 2362, 1727,
1593, 1534, 1482, 1448, 1379, 1263, 1178, 1120, 1076, 1024,
817, 156, 670, 576, 542 cmÀ1.
Acknowledgements
The authors thank the Program for New Century Excellent
Talents in University by Ministry of Education (Grant No.
NCET-10-0371), the Fundamental Research Funds for the
Central Universities (Grant No. 2009M0262), the National
Natural Science Foundation of China (No. 21072063), the Re-
turned Overseas Chinese Scholars and State Education Min-
istry (No. 2010-1174), Research Fund for the Doctoral Pro-
gram of Higher Education of China (No. 20100172120020)
and Guangdong Natural Science Foundation (No.
10351064101000000) for financial support.
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Adv. Synth. Catal. 2011, 353, 2795 – 2804
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2804
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Adv. Synth. Catal. 2011, 353, 2795 – 2804