Sulfonylamidation of alkylbenzenes at benzylic position with p-toluenesulfonamide and 1,3-diiodo-5,5-dimethylhydantoin

Article abstract of DOI:10.1016/j.tetlet.2010.02.060

Treatment of alkylbenzenes with p-toluenesulfonamide and 1,3-diiodo-5,5-dimethylhydantoin (DIH) in a small amount of carbon tetrachloride at 60 °C gave the corresponding α-p-toluenesulfonylamido)alkylbenzenes in good to moderate yields. The present reaction is a simple method for the α-sulfonylamidation of the benzylic position in alkylbenzenes.

Full text of DOI:10.1016/j.tetlet.2010.02.060

Tetrahedron Letters 51 (2010) 2063–2066
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Tetrahedron Letters
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Sulfonylamidation of alkylbenzenes at benzylic position
with p-toluenesulfonamide and 1,3-diiodo-5,5-dimethylhydantoin
*
Haruka Baba, Hideo Togo
Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Treatment of alkylbenzenes with p-toluenesulfonamide and 1,3-diiodo-5,5-dimethylhydantoin (DIH) in a
Received 21 January 2010
Revised 8 February 2010
Accepted 12 February 2010
Available online 16 February 2010
small amount of carbon tetrachloride at 60 °C gave the corresponding
benzenes in good to moderate yields. The present reaction is a simple method for the
tion of the benzylic position in alkylbenzenes.
a-p-toluenesulfonylamido)alkyl-
a-sulfonylamida-
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
1,3-Diiodo-5,5-dimethylhydantoin
Alkylbenzene
p-Toluenesulfonamide
a-(p-Toluenesulfonylamido)alkylbenzene
Sulfonamidyl radical
The use of trivalent iodines in organic synthesis has been stud-
ied widely.1 In particular, (diacetoxyiodo)benzene (DIB) is the most
popular and useful trivalent iodine reagent for organic synthesis as
an alternative to toxic heavy-metal reagents.2 The advantages of
DIB are that it is a non-metal oxidant and can be used for not only
polar reactions but also radical reactions to generate oxygen-cen-
tered radicals, nitrogen-centered radicals, and carbon-centered
radicals.3 For the radical reactions, a DIB–iodine system is used
and the initial formation of acetyl hypoiodite (CH3CO2I) from the
reaction of DIB and iodine is the key step.4 The synthetic reactions
of alkoxyl radicals derived from substrates, such as steroidal alco-
hols and sugars, with DIB and iodine have been well studied by
Suarez et al.3 We have also examined the utility of nitrogen-cen-
tered radicals for the construction of tetrahydroquinolines, benzo-
sultams, and saccharins from sulfonamides with DIB and iodine
under irradiation with a tungsten lamp,5 and oxygen-centered rad-
icals for the construction of chromans from 3-arylpropanols with
DIB and iodine under irradiation with a tungsten lamp.6 The forma-
tion of tetrahydroquinolines, benzosultams, and chromans pro-
ceeds through the intramolecular cyclization of the formed
sulfonamidyl radicals and alkoxyl radicals onto their aromatic
benzylic position by the formed p-toluenesulfonamidyl radical
and shows promise for the direct preparation of a-(p-toluenesulf-
onylamido)alkylbenzenes from alkylbenzenes. On the other hand,
although 1,3-diiodo-5,5-dimethylhydantoin (DIH) is not a hyper-
valent iodine compound, it may work as a synthon of unstable
acetyl hypoiodite derived from the reaction of DIB and iodine.
Here, as part of our synthetic study of DIH,8 which may work as
a synthon in the reaction of DIB and iodine, we would like to report
a simple method for the preparation of
a-(p-toluenesulfonylami-
do)alkylbenzenes, which involves the reaction of alkylbenzenes
with p-toluenesulfonamide and DIH alone under warming condi-
tions. DIH is not a hypervalent iodine compound and its structure
is similar to that of N-iodosuccinimide (NIS). However, as DIH has
two N–I bonds, it is expected to be more effective and efficient than
NIS. Although synthetic studies of DIH are extremely limited, it is
used for the iodination of aromatic compounds.9
First, ethylbenzene was treated with p-toluenesulfonamide in
the presence of DIH alone, similar to the DIB–iodine system, in a
small amount of carbon tetrachloride (0.5 mL), as shown in Table
1, and the corresponding
was obtained in moderate to good yields, depending on the
amounts of DIH and ethylbenzene used (entries 1–7). -(p-Tolu-
a-(p-toluenesulfonylamido)ethylbenzene
rings. Recently, the
a-sulfonylamidation of alkylbenzenes with
a
DIB and iodine at 50 °C without solvent was reported to provide
enesulfonylamido)ethylbenzene was obtained in good yield when
the reaction was carried out with DIH (1.8 mmol), ethylbenzene
(5 mmol), and p-toluenesulfonamide (1.0 mmol) at 60 °C (entry
6).10 Here, an excess amount of ethylbenzene was required to fur-
a-(p-toluenesulfonylamido)alkylbenzenes in moderate to good
yields.7 This reaction proceeds through an intermolecular pathway
via the hydrogen atom abstraction from alkylbenzenes at the
nish
a-(p-toluenesulfonylamido)ethylbenzene in good yield, and
non-reacted ethylbenzene was recovered in high yield (ꢀ90%).
* Corresponding author.
E-mail address: togo@faculty.chiba-u.jp (H. Togo).
When the same reaction was carried out in the presence of galvin-
0040-4039/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2010.02.060

2064
H. Baba, H. Togo / Tetrahedron Letters 51 (2010) 2063–2066
Table 1
Table 2
Sulfonylamidation of ethylbenzene with TsNH2 and DIH
Sulfonylamidation of alkylbenzenes with TsNH2 and DIH
DIH (1.8 equiv.),
TsNH2 (1.0 equiv.)
R2
R3
NHTs
DIH, TsNH2
R2
R3
R1
R1
CCl4 (0.5 mL),
60°C 24 h
CCl4 (0.5 mL),
60°C 24 h
NHTs
1a
2a
1
2
Entry
TsNH2 (mmol)
1a (mmol)
DIH (mmol)
2a
Entry
R1–
R2–
R3–
2
Yielda (%)
Yielda (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1.1
1
1
1
1
1
1
1
1
1
3
3
5
5
5
5
5
5
5
5
5
5
5
5
1
1
0.6
1
25
45
31
55
82
90
89
0
57
11
0
75
0
1
2
3
4
5
H
H
H
H
Br
C(CH3)3
C2H5
OCH3
CON(CH3)2
CO2CH3
Fluorene
Diphenylmethane
H
CH3
H
H
H
H
H
H
H
H
H
H
90 (2a)
58 (2b)
60 (2c)
65 (2d)
63 (2e)
83 (2f)
79 (2g)
84 (2h)
15 (2i)
40 (2j)
53 (2k)
89 (2l)
40 (2m)
37 (2n)
30 (2o)
37 (2p)
44 (2q)
CH2CH3
(CH2)2CH3
(CH2)2OAC
CH3
CH3
CH3
CH3
CH3
CH3
1.5
1.8
2.0
1.8b
3.6c
3.6d
3.6e
1.8f
1.8g
1.8
1.8
6
7b
8c
9
1
1
1
10
11d
12d
13b
14
15e
16e
17e
1
CH3
CH3
H
H
H
CH3
C2H5
H
H
H
1h
1i
1
23
H
C(CH3)3
H
Br
a
b
c
d
e
f
Isolated yield based on TsNH2.
Galvinoxyl-free radical (1.0 equiv) was added.
Instead of DIH, N-iodosuccinimide (3.6 mmol) was used.
Instead of DIH, N-bromosuccinimide (3.6 mmol) was used.
Instead of DIH, I2 (3.6 mmol) was used.
Irradiated with a tungsten lamp at 50 °C for 6 h.
Under ultrasonic irradiation at 40 °C for 6 h.
Instead of TsNH2, p-CH3C6H4CONH2 was used.
Instead of TsNH2, CH3SO2NH2 was used.
a
b
c
Isolated yield based on TsNH2.
Reaction was carried out under dark conditions.
DIH (6.7 equiv) was used.
K2CO3 (1.0 equiv) was added.
Substrate (10 equiv) was used.
d
e
g
h
i
2h:
CH3O
2i:
CH3
CH3
NHTs
CH3
CH3
O
(CH3)2NOC
O
CH3
I
DIH:
I
N
2j:
NHTs
N
2k:
I
CH3O2C
O
O
NHTs
2l:
oxyl-free radical (1.0 equiv), a-(p-toluenesulfonylamido)ethylben-
zene was not obtained at all (entry 8) and ethylbenzene was
recovered quantitatively. Thus, the results indicate that the present
reaction proceeds through the formation of radical species. NIS also
treatment of p-(methoxy)ethylbenzene with p-toluenesulfonamide
and an excess amount of DIH generated 3-iodo-4-methoxy-1- -(p-
worked to provide
a-(p-toluenesulfonylamido)ethylbenzene in
a
moderate yield (entry 9), although 3.6 equiv of NIS was required.
Meanwhile, N-bromosuccinimide (NBS) did not work well and
the starting material was recovered (entry 10), and molecular
iodine did not work at all (entry 11). When the present reaction
toluenesulfonamido)ethylbenzene in good yield (entry 8). However,
the treatment of N,N-dimethyl p-ethylbenzamide and methyl p-eth-
ylbenzoate with p-toluenesulfonamide and DIH gave N,N-dimethyl
p-acetylbenzamide and methyl p-acetylbenzoate in moderate to
was carried out under irradiation with a tungsten lamp,
a
-(p-tolu-
low yields, without the formation of N,N-dimethyl p-
a-(toluene-
enesulfonylamido)ethylbenzene was obtained in good yield (entry
12). In contrast, the product was not obtained at all under ultra-
sonic irradiation (entry 13). The same treatment with p-toluamide
and methanesulfonamide, instead of p-toluenesulfonamide, did
sulfonamido)ethylbenzamide and methyl p- -(toluenesulfonami-
a
do)ethylbenzoate (entries 9 and 10). Recently, the Wohl–Ziegler
reaction of 3,4-dibromo-6-methylbenzyl ethyl ether with NBS in
CCl4 was reported to give unexpected ethyl 3,4-dibromo-6-meth-
ylbenzoate instead of 3,4-dibromo-6-(bromomethyl)benzyl ethyl
ether.11 Thus, in the present reactions, ethylbenzene derivatives
not work well, providing the corresponding
a-(p-toluamido)ethyl-
benzene and -(methanesulfonylamido)ethylbenzene in poor
a
yields, respectively (entries 14 and 15).
Basedontheseresults, propylbenzene, butylbenzene, and3-acet-
oxypropylbenzene were treated with p-toluenesulfonamide in the
might be converted into
derivatives through the formation of N-iodo-
a
-(p-toluenesulfonylimino)ethylbenzene
-(p-toluenesulfony-
a
lamido)ethylbenzene derivatives and the subsequent elimination
of HI, followed by the hydrolysis to acetylbenzene derivatives. The
same treatment of fluorine and diphenylmethane provided the
corresponding sulfonylamidated products in good to moderate
yields (entries 11 and 12). The same treatment of tertiary alkyl ben-
zenes, such as cumene and sec-butylbenzene, with p-toluenesulfon-
amide and DIH gave the corresponding
derivatives in moderate yields (entries 13 and 14). The same
treatment of toluene derivatives with DIH and p-toluenesulfon-
amide provided the corresponding a-toluenesulfonylamide deriva-
presence of DIH to give the corresponding a-(p-toluenesulfonylam-
ido)alkylbenzenes in good yields, as shown in Table 2 (entries 2–4).
The same treatment of p-(bromo)ethylbenzene, p-(t-butyl)ethyl-
benzene, and p-diethylbenzene with p-toluenesulfonamide and
DIH provided the corresponding sulfonylamidated compounds at
the benzylic position in good yields (entries 5–7), although the reac-
tion of p-diethylbenzene was carried out under dark conditions. In
these reactions, non-reacted alkylbenzenes were recovered in
approximately 80–92% yields. When p-(methoxy)ethylbenzene, an
electron-rich aromatic compound, was used as a substrate, iodin-
ation on the aromatic ring occurred at first by DIH. Therefore, the
a-toluenesulfonylamide
tives in moderate yields (entries 15–17). When the Wohl–Ziegler
reaction of ethylbenzene and p-bromotoluene with NBS and AIBN

H. Baba, H. Togo / Tetrahedron Letters 51 (2010) 2063–2066
2065
R2
Science, and Technology, in Japan and Iodine research project in
Chiba University is gratefully acknowledged. The authors thank
Nippoh Chemicals Co. for the gift of DIH.
AIBN (0.1 equiv.),
NBS (1.0 equiv.)
R2
Br
R1
R1
CCl4 (1 mL), 80°C
4 h
R1 = H, R2 = CH3 90%
R1 = Br, R2 = H 77%
References and notes
AIBN (0.1 equiv.),
NBS (1.0 equiv.),
TsNH2 (1.0 equiv.),
R2
1. Varvoglis, A. Hypervalent Iodine in Organic Synthesis; Academic Press: San Diego,
1997.
R2
R1
R1
2. Reviews: (a) Moriarty, R. M.; Vaid, R. K. Synthesis 1990, 431; (b) Stang, P. J.
Angew. Chem., Int. Ed. Engl. 1992, 31, 274; (c) Prakash, O.; Saini, N.; Sharma, P. K.
Synlett 1994, 221; (d) Kitamura, T. Yuki Gosei Kagaku Kyokaishi 1995, 53, 893;
(e) Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996, 96, 1123; (f) Umemoto, T. Chem.
Rev. 1996, 96, 1757; (g) Kita, Y.; Takada, T.; Tohma, H. Pure Appl. Chem. 1996, 68,
627; (h) Togo, H.; Hoshina, Y.; Nogami, G.; Yokoyama, M. Yuki Gosei Kagaku
Kyokaishi 1997, 55, 90; (i) Varvoglis, A. Tetrahedron 1997, 53, 1179; (j)
Zhdankin, V. V. Rev. Heteroat. Chem. 1997, 17, 133; (k) Muraki, T.; Togo, H.;
Yokoyama, M. Rev. Heteroat. Chem. 1997, 17, 213; (l) Kitamura, T.; Fujiwara, Y.
Org. Prep. Proc. Int. 1997, 29, 409; (m) Varvoglis, A.; Spyroudis, S. Synlett 1998,
221; (n) Zhdankin, V. V.; Stang, P. J. Tetrahedron 1998, 54, 10927; (o) Moriarty,
R. M.; Prakash, O. Adv. Heterocycl. Chem. 1998, 69, 1; (p) Togo, H.; Katohgi, M.
Synlett 2001, 565; (q) Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2002, 102, 2523; (r)
Richardson, R. D.; Wirth, T. Angew. Chem., Int. Ed. 2006, 45, 4402; (s) Ladziata,
U.; Zhdankin, V. Synlett 2007, 527.
3. Review: (a) Togo, H.; Katohgi, M. Synlett 2001, 565; Papers: (b) de Armas, P.;
Carrau, R.; Concepcion, J. I.; Francisco, C. G.; Hernandez, R.; Suarez, E.
Tetrahedron Lett. 1985, 26, 2493; (c) Freire, R.; Marrero, J. J.; Rodriguez, M. S.;
Suarez, E. Tetrahedron Lett. 1986, 27, 383; (d) Freire, R.; Hernandez, R.;
Rodriguez, M. S.; Suarez, E.; Perales, P. Tetrahedron Lett. 1987, 28, 981; (e)
Francisco, C. G.; Freire, R.; Rodriguez, M. S.; Suarez, E. Tetrahedron Lett. 1987, 28,
3397; (f) Carrau, R.; Hernandez, R.; Suarez, E.; Betancor, C. J. Chem. Soc., Perkin
Trans. 1 1987, 937; (g) Hernandez, R.; Medina, M. C.; Salazar, J. A.; Suarez, E.
Tetrahedron Lett. 1987, 28, 2533; (h) de Armas, P.; Francisco, C. G.; Hernandez,
CCl4 (1 mL), 80°C
24 h
NHTs
R1 = H, R2 = CH3 23%
R1 = Br, R2 = H
4%
Scheme 1.
R2
R2
DIH, TsNH2
R1
R1
CCl4, 60°C 24 h
NHTs
DIH
TsNH-I
TsNH2
(-HI)
TsNH2
Δ
(- I•)
R2
•
R1
( I•)
R1
TsNH
I
R2
R2
R1
•
R.; Salazar, J. A.; Suarez, E. J. Chem. Soc., Perkin Trans.
1 1988, 3255; (i)
Hernandez, R.; Marrero, J. J.; Suarez, E. Tetrahedron Lett. 1988, 29, 5979; (j)
Hernandez, R.; Marrero, J. J.; Melian, D.; Suarez, E.; Melian, D. Tetrahedron Lett.
1988, 29, 6661; (k) Hernandez, R.; Marrero, J. J.; Suarez, E. Tetrahedron Lett.
1989, 30, 5501; (l) Dorta, R. L.; Francisco, C. G.; Suarez, E. Chem. Commun. 1989,
1168; (m) Arencibia, M. T.; Freire, R.; Perales, A.; Rodriguez, M. S.; Suarez, E. J.
Chem. Soc., Perkin Trans. 1 1991, 3349; (n) Boto, A.; Betancor, C.; Prange, T.;
Suarez, E. Tetrahedron Lett. 1992, 33, 6687; (o) de Armas, P.; Francisco, C. G.;
Suarez, E. Angew. Chem., Int. Ed. Engl. 1992, 31, 772; (p) Inanaga, J.; Sugimoto, Y.;
Yokoyama, Y.; Hanamoto, T. Tetrahedron Lett. 1992, 33, 8109; (q) de Armas, P.;
Francisco, C. G.; Suarez, E. J. Am. Chem. Soc. 1993, 115, 8865; (r) Boto, A.;
Betancor, C.; Hernandez, R.; Rodriguez, M. S.; Suarez, E. Tetrahedron Lett. 1993,
34, 4865; (s) de Armas, P.; Francisco, C. G.; Suarez, E. Tetrahedron Lett. 1993, 34,
Scheme 2. Plausible reaction mechanism.
in CCl4 was carried out, a-bromoethylbenzene and p-bromobenzyl-
bromide were obtained in good yields, respectively, as shown in
Scheme 1. However, when the same reactions of ethylbenzene and
p-bromotoluene with NBS and AIBN in CCl4 in the presence of p-tol-
uenesulfonamide were carried out, a-(p-toluenesulfonamido)ethyl-
benzene and N-(p-bromobenzyl)-p-toluenesulfonamide were
obtained in low yields even if the reactions were carried out for
24 h at 80 °C. Therefore, the present reactions might be a good meth-
7331; (t) Boto, A.; Betancor, C.; Suarez, E. Tetrahedron
Lett. 1994, 35, 5509; (u)
Boto, A.; Betancor, C.; Suarez, E. Tetrahedron Lett. 1994, 35, 6933; (v) Arencibia,
T.; Salazar, J. A.; Suarez, E. Tetrahedron Lett. 1994, 35, 7463; (w) Hernandez, R.;
Velazquez, S. M.; Suarez, E.; Rodriguez, M. S. J. Org. Chem. 1994, 59, 6395; (x)
Lee, J.; Oh, J.; Jin, S. J.; Choi, J. R.; Atwood, J. L.; Cha, J. K. J. Org. Chem. 1994, 59,
6955; (y) Boto, A.; Betancor, C.; Prange, T.; Suarez, E. J. Org. Chem. 1994, 59,
4393.
od for the preparation of
a-(p-toluenesulfonamido)alkylbenzenes
from alkylbenzenes directly with DIH alone.
The plausible reaction mechanism is shown in Scheme 2. Thus,
based on the previous synthetic study of DIH,8 the initial formation
of N-iodo-p-toluenesulfonamide from the reaction of p-toluenesul-
fonamide and DIH occurs, followed by homolytic cleavage to
generate a sulfonamidyl radical. The sulfonamidyl radical abstracts
a benzylic hydrogen atom from alkylbenzene to provide a benzyl
radical that may react with an iodine atom. Once a benzylic iodide
is formed, it smoothly reacts with p-toluenesulfonamide to give
-(p-toluenesulfonamido)alkylbenzene. Therefore, galvinoxyl-free
radical completely retards the present reaction.
In conclusion, treatment of alkylbenzenes with p-toluenesul-
fonamide and 1,3-diiodo-5,5-dimethylhydantoin (DIH) alone at
4. (a) Ogata, Y.; Aoki, K. J. Am. Chem. Soc. 1968, 90, 6187; (b) Merkushev, E. B.;
Simakhina, N. D.; Koveshnikova, G. M. Synthesis 1980, 486.
5. (a) Togo, H.; Katohgi, M.; Yokoyama, M. Synlett 1998, 131; (b) Togo, H.;
Hoshina, Y.; Muraki, T.; Nakayama, H.; Yokoyama, M. J. Org. Chem. 1998, 63,
5193; (c) Katohgi, M.; Togo, H.; Yamaguchi, K.; Yokoyama, M. Tetrahedron 1999,
55, 14885; (d) Togo, H.; Nabana, T.; Yokoyama, M. J. Org. Chem. 2000, 65, 8391;
(e) Togo, H.; Harada, Y.; Yokoyama, M. J. Org. Chem. 2000, 65, 926.
6. (a) Muraki, T.; Togo, H.; Yokoyama, M. Tetrahedron Lett. 1996, 37, 2441; (b)
Togo, H.; Muraki, T.; Hoshina, Y.; Yamaguchi, K.; Yokoyama, M. J. Chem. Soc.,
Perkin Trans. 1 1997, 787.
a
7. Fan, R.; Li, W.; Pu, D.; Zhang, L. Org. Lett. 2009, 11, 1425.
8. (a) Iida, S.; Togo, H. Synlett 2007, 407; (b) Iida, S.; Togo, H. Tetrahedron 2007, 63,
8274; (c) Takahashi, S.; Togo, H. Heterocycles 2008, 76, 507; (d) Takahashi, S.;
Togo, H. Synthesis 2009, 2329; (e) Moroda, A.; Furuyama, S.; Togo, H. Synlett
2009, 1336; (f) Iida, S.; Ohmura, R.; Togo, H. Tetrahedron 2009, 65, 6257.
9. Orazi, O. O.; Corral, R. A.; Bertorello, H. E. J. Org. Chem. 1965, 30, 1101.
60 °C gave the corresponding
benzenes in good to moderate yields. The present reaction is a sim-
ple tool for the -sulfonylamidation at the benzylic position of
a-(p-toluenesulfonylamido)alkyl-
10. Typical procedure for preparation of
ethylbenzene, DIH, and
dimethylhydantoin (1.8 mmol, 684 mg) was added to
a
-(p-toluenesulfonylamido)ethylbenzene with
p-toluenesulfonamide: 1,3-Diiodo-5,5-
solution of
a
alkylbenzenes. The advantages of DIH are that it is pale yellow
solid and does not sublimate, and can be used alone for the present
radical reactions, instead of the combination of (diacetoxy-
iodo)benzene and molecular iodine (it sublimates). Thus, the
present method is much more effective and simpler than the
previous DIB and molecular iodine system.
a
ethylbenzene (5.0 mmol, 531 mg) and p-toluenesulfonamide (1.0 mmol,
171 mg) in carbon tetrachloride (0.5 mL). The mixture was warmed at 60 °C
for 24 h under an argon atmosphere. After the reaction, the mixture was
poured into saturated aqueous sodium sulfite solution and extracted with
CHCl3 (3 Â 20 mL). Then, the organic layer was dried over Na2SO4. After
filtration and removal of the solvent under reduced pressure, the residue was
subjected to preparative TLC on silica gel using a mixture of hexane, ethyl
acetate, and chloroform (6:3:1) as an eluent to give
toluenesulfonylamido)ethylbenzene in 90% (254 mg) yield.
a-(p-
Acknowledgments
a
-(p-Toluenesulfonylamido)ethylbenzene: Mp 83 °C; IR (Nujol): 1017, 1120,
1157, 1209, 1376, 3251 cmÀ1
;
1H NMR (CDCl3, TMS) d = 1.42 (d, J = 6.8 Hz, 3H),
Financial support in the form of a Grant-in-Aid for Scientific Re-
search (20550033) from the Ministry of Education, Culture, Sports,
2.39 (s, 3H), 4.46 (quintet, J = 6.8 Hz, 1H), 4.63 (br s, 1H), 7.10 (d, J = 8.5 Hz, 2H),
7.17–7.23 (m, 5H), 7.62 (d, J = 8.5 Hz, 2H); Elemental Anal. Calcd for

2066
H. Baba, H. Togo / Tetrahedron Letters 51 (2010) 2063–2066
C15H17NO2S: C, 65.43; H, 6.22, N, 5.09%. Found: C, 65.20; H, 6.05; N, 5.05.
-(p-Toluenesulfonylamido)propylbenzene: Mp 102 °C; IR (Nujol): 1003, 1046,
1092, 1162, 1376, 3272 cmÀ1 1H NMR (CDCl3, TMS) d = 0.80 (t, J = 7.2 Hz, 3H),
1.67–1.86 (m, 2H), 2.35 (s, 3H), 4.19 (q, J = 7.2 Hz, 1H), 4.68 (d, J = 7.2 Hz, 1H),
6.99–7.02 (m, 2H), 7.12 (d, J = 8.4 Hz, 2H), 7.14–7.18 (m, 3H), 7.53 (d, J = 8.4 Hz,
2H); Elemental Anal. Calcd for C16H19NO2S: C, 66.41; H, 6.62; N, 4.84. Found: C,
66.04; H, 6.57; N, 4.74.
N-(
a
,
a
-Dimethylbenzyl)-p-toluenesulfonamide: Mp 138–141 °C; IR (Nujol):
1H NMR (CDCl3, TMS) d = 1.65 (s, 6H), 2.38 (s,
a
1076, 1154, 1376, 3364 cmÀ1
;
;
3H), 4.97 (br s, 1H), 7.22–7.14 (m, 5H), 7.30 (d, J = 8.1 Hz, 2H), 7.57 (d,
J = 8.1 Hz, 2H). Elemental Anal. Calcd for C16H19NO2S: C, 66.41; H, 6.62; N, 4.84.
Found: C, 66.25; H, 6.60; N, 4.80.
N-(
a
-Ethyl-
a
-methylbenzyl)-p-toluenesulfonamide: Mp 107–108 °C; IR (Nujol):
1033, 1096, 1150, 1376, 3275 cmÀ1
;
1H NMR (CDCl3, TMS) d = 0.70 (t, J = 7.5 Hz,
a
-(p-Toluenesulfonylamido)butylbenzene: Mp 83 °C; IR (Nujol): 1047, 1094,
3H), 1.62 (s, 3H), 1.99–1.81 (m, 2H), 2.38 (s, 3H), 4.80 (s, 1H), 7.21–7.12 (m,
5H), 7.26–7.22 (m, 2H), 7.54 (d, J = 8.0 Hz, 2H). Elemental Anal. Calcd for
C17H21NO2S: C, 67.29; H, 6.98; N, 4.62. Found: C, 67.32; H, 6.92; N, 4.62.
1161, 1376, 3265 cmÀ1 1H NMR (CDCl3, TMS) d = 0.83 (t, J = 7.2 Hz, 3H), 1.10–
;
1.32 (m, 2H), 1.62–1.79 (m, 2H), 2.35 (s, 3H), 4.27 (q, J = 7.2 Hz, 1H), 4.66 (d,
J = 7.2 Hz, 1H), 6.98–7.02 (m, 2H), 7,10 (d, J = 8.2 Hz, 2H), 7.15–7.18 (m, 3H),
7.51(d, J = 8.2 Hz, 2H); Elemental Anal. Calcd for C17H21NO2S: C, 67.29; H, 6.98;
N, 4.62. Found: C, 67.13; H, 6.98; N, 4.58.
N-(
a
-Methyl-4-ethylbenzyl)-p-toluenesulfonamide: Mp 89–91 °C; IR (Nujol)
1019, 1079, 1158, 1324, 1460, 3250 cmÀ1
;
1H NMR (CDCl3, TMS) d = 1.18 (t,
J = 7.6 Hz, 3H), 1.42 (d, J = 6.7 Hz, 3H), 2.37 (s, 3H), 2.57 (q, J = 7.6 Hz, 2H), 4.43
(quintet, J = 6.7 Hz, 1H), 4.78(d, J = 6.7 Hz, 1H), 7.01 (d, J = 8.2 Hz, 4H), 6.99 (d,
J = 8.3 Hz, 2H), 7.02 (d, J = 8.3 Hz, 2H), 7.60 (d, J = 8.3 Hz, 2H); Elemental Anal.
Calcd for C17H21NO2S: C, 67.29; H, 6.98; N, 4.62. Found: C, 67.18; H, 6.98; N,
4.55.
c
-Acetoxy-
a
-(p-toluenesulfonylamido)propylbenzene: Oil; IR (Nujol): 1042, 1159,
1376, 1737, 3268 cmÀ1
;
1H NMR (CDCl3, TMS) d = 2.00 (s, 3H), 2.00–2.18 (m,
2H), 2.36 (s, 3H), 3.87–4.05 (m, 2H), 4.45 (q, J = 7.2 Hz, 1H), 4.98 (br s. 1H),
7.01–7.04 (m, 2H), 7.16 (d, J = 8.2 Hz, 2H), 7.16–7.20 (m, 3H), 7.54 (d, J = 8.2 Hz,
2H); HRMS (ESI) Calcd for C18H21NO4SNa: m/z 370.1084, Found m/
z = 370.1077.
N-(4-tButylbenzyl)-p-toluenesulfonamide: Mp 108–110 °C; IR (Nujol): 1056,
1093, 1150, 1462, 3270 cmÀ1 1H NMR (CDCl3, TMS) d = 1.17 (s, 9H), 2.34 (s,
;
9-(p-Toluenesulfonylamido)fluorene: Mp 199 °C; IR (Nujol): 1064, 1154, 1182,
3H), 4.00 (d, J = 6.1 Hz, 2H), 4.73 (br s, 1H), 7.03 (d, J = 8.4 Hz, 2H), 7.20 (d,
J = 8.4 Hz, 4H), 7.66 (d, J = 8.4 Hz, 2H); Elemental Anal. Calcd for C18H23NO2S: C,
68.10; H, 7.30; N, 4.41. Found: C, 67.76; H, 7.31; N, 4.33.
1376, 3309 cmÀ1 1H NMR (CDCl3, TMS) d = 2.51 (s, 3H), 4.76 (d, J = 9.6 Hz, 1H),
;
5.40 (d, J = 9.6 Hz, 1H), 7.19–7.23 (m, 4H), 7.32–7.40 (m, 2H), 7.42 (d, J = 8.5 Hz,
2H), 7.63 (d, J = 7.5 Hz, 2H), 7.97 (d, J = 8.5 Hz, 2H); Elemental Anal. Calcd for
C20H17NO2S: C, 71.62; H, 5.11; N, 4.18. Found: C, 71.28; H, 4.84; N, 4.11.
N-Diphenylmethyl-p-toluenesulfonylamide: Mp 160 °C; IR (Nujol): 1027, 1058,
4-tButyl-
1160, 1376, 3255 cmÀ1
a
-(p-toluenesulfonamido)ethylbenzene: Oil; IR (Nujol): 1026, 1078,
;
1H NMR (CDCl3, TMS) d = 1.26 (s, 9H), 1.43 (d,
J = 6.7 Hz, 3H), 2.36 (s, 3H), 4.45 (quintet, J = 6.7 Hz, 1H), 4.85 (d, J = 6.7 Hz, 1H),
7.00 (d, J = 8.2 Hz, 2H), 7.14 (d, J = 8.2 Hz, 2H), 7.19 (d, J = 8.2 Hz, 2H), 7.58 (d,
J = 8.2 Hz, 2H); HRMS (ESI) Calcd for C19H25NO2SNa: m/z 354.1498, Found m/z
354.1487.
1086, 1160, 1376, 3244 cmÀ1 1H NMR (CDCl3, TMS) d = 2.37 (s, 3H), 4.98 (d,
;
J = 7.0 Hz, 1H), 5.56 (d, J = 7.0 Hz, 1H), 7.06–7.11 (m, 4H), 7.15 (d, J = 8.0 Hz,
2H), 7.19–7.25 (m, 6H), 7.56 (d, J = 8.0 Hz, 2H); Elemental Anal. Calcd for
C20H19NO2S: C, 71.19; H, 5.68; N, 4.15. Found: C, 70.91; H, 5.53; N, 3.99.
N-(4-Bromobenzyl)-p-toluenesulfonamide: Mp 105 °C; IR (Nujol): 1064, 1156,
3-Iodo-4-methoxy-1-
a
-(p-toluenesulfonylamido)ethylbenzene: Mp 115 °C; IR
1376, 3263 cmÀ1 1H NMR (CDCl3, TMS) d = 2.44 (s, 3H), 4.09 (d, J = 6.1 Hz, 2H),
;
(Nujol): 1016, 1046, 1159, 1202, 1339, 3240 cmÀ1
;
1H NMR (CDCl3, TMS)
4.67 (t, J = 6.1 Hz, 1H), 7.08 (d, J = 8.2 Hz, 2H), 7.32 (d, J = 8.3 Hz, 2H), 7.40 (d,
J = 8.2 Hz, 2H), 7.73 (d, J = 8.3 Hz, 2H); Elemental Anal. Calcd for C14H14BrNO2S:
C, 49.42; H, 4.15; N, 4.12. Found: C, 49.20; H, 3.92; N, 4.12.
d = 1.38 (d, J = 6.8 Hz, 3H), 2.40 (s, 3H), 3.82 (s, 3H), 4.38 (quintet, J = 6.8 Hz,
1H), 4.76 (d, J = 6.8 Hz, 1H), 6.63 (d, J = 8.3 Hz, 1H), 7.08 (d, J = 8.3 Hz, 1H), 7.17
(d, J = 8.1 Hz, 2H), 7.26 (s, 1H), 7.56 (d, J = 8.1 Hz, 2H); Elemental Analysis Calcd
for C16H18NO3SI: C, 44.56; H, 4.21; N, 3.25. Found: C, 44.98; H, 4.20; N, 3.22.
N-Benzyl-p-toluenesulfonamide: Mp 107–109 °C; IR (Nujol): 1027, 1058, 1081,
1162, 1376, 3267 cmÀ1 1H NMR (CDCl3, TMS) d = 2.33 (s, 3H), 4.13 (d,
;
4-Bromo-
a
-(p-toluenesulfonylamido)ethylbenzene: Mp 141 °C; IR (Nujol): 1022,
J = 6.4 Hz, 2H), 4.56 (br s, 1H), 7.19 (d, J = 7.8 Hz, 2H), 7.24–7.30 (m, 3H), 7.31
(d, J = 8.4 Hz, 2H), 7.77 (d, J = 8.4 Hz, 2H); Elemental Anal. Calcd for
C14H15NO2S: C, 64.34; H, 5.79; N, 5.36. Found: C, 64.13; H, 5.68; N, 5.30.
11. Gauna, G. A.; Cobice, D.; Awruch, J. Tetrahedron 2008, 64, 7242.
1160, 1338, 3240 cmÀ1
;
1H NMR (CDCl3, TMS) d = 1.38 (d, J = 6.9 Hz, 3H), 2.40
(s, 3H), 4.38 (quintet, J = 6.9 Hz, 1H), 4.73 (br s, 1H), 6.96 (d, J = 8.5 Hz, 2H), 7.18
(d, J = 8.1 Hz, 2H), 7.30 (d, J = 8.5 Hz, 2H), 7.56 (d, J = 8.1 Hz, 2H); Elemental
Anal. Calcd for C15H16BrNO2S: C, 50.86; H, 4.55; N, 3.95. Found: C, 50.54; H,
4.34; N, 3.89.