Synthesis of E-aryl ethenesulfonamides: A simple one-pot, two-step procedure from 1-hydroxy-1-arylalkanes

Article abstract of DOI:10.1021/jo034770f

The unusual reactivity of 1-phenyl-1-ethane-sulfonic acid in thionyl chloride was investigated. Mechanistic considerations led us to set up a new and efficient synthesis of E-arylethenesulfonamides starting from 1-hydroxy-1-arylalkanes. The easy availability of the starting materials and the straightforward, one-pot procedure make this process an attractive method for the preparation of these compounds currently largely employed in chemical and pharmaceutical fields.

Full text of DOI:10.1021/jo034770f

Syn th esis of E-Ar yl Eth en esu lfon a m id es: A
Sim p le On e-P ot, Tw o-Step P r oced u r e fr om
1-Hyd r oxy-1-a r yla lk a n es
Andrea Aramini,* Maria C. Cesta, Silvia Coniglio,
Christian Bijani, Sandro Colagioia, Valerio D’Elia, and
Marcello Allegretti*
F IGURE 1.
Chemistry Department, Dompe´ Research and Development,
Dompe´ S.p.A., V. Campo di Pile, 67100 L’Aquila, Italy
TABLE 1. P er cen ta ge of Detected Com p ou n d s a t
Differ en t Rea ction Tim esa ,b
andrea.aramini@dompe.it; marcello.allegretti@dompe.it
Received J une 5, 2003
entry
timec (h)
2
4
5
7
1
2
3
4
1
5
8
90
66
40
7
<2
15
34
80
<2
<2
<2
<2
<2
17
24
7
Abstr a ct: The unusual reactivity of 1-phenyl-1-ethane-
sulfonic acid in thionyl chloride was investigated. Mecha-
nistic considerations led us to set up a new and efficient
synthesis of E-arylethenesulfonamides starting from 1-hy-
droxy-1-arylalkanes. The easy availability of the starting
materials and the straightforward, one-pot procedure make
this process an attractive method for the preparation of these
compounds currently largely employed in chemical and
pharmaceutical fields.
12
a
Conversion of the starting material is complete after 1 h.
Yields calculated on isolated product. c Refluxing time of 1 in
b
SOCl2; After removal of SOCl2 the residue was treated with
ammonia (see the Experimental Section).
our hands, 1-(4-isobutylphenyl)ethanesulfonic acid 1
undergoes the described desulfonylation reaction when
heated at reflux in CHCl3 with 3 equiv of thionyl chloride
(SOCl2); surprisingly, besides the main product 2, small
amounts of the rearranged ethenesulfonyl chloride 3 were
also detected in the reaction mixture. Final treatment
with ammonia affords the corresponding ethenesulfona-
mide 4 in low yields (Scheme 1).
Sulfonamides are widely employed molecules in phar-
maceutical research.1,2 We have recently described3
a
novel class of acylmethanesulfonamides derived from (S)
and (R) 2-arylpropionic acids showing the ability to
inhibit IL-8 biological activities mediated by the cognate
receptors CXCR1 and CXCR2.
Further experiments have shown that the reaction
time and the amount of SOCl2 favorably affect the yield
of unsaturated compound 4. Hence we decided to follow
and isolate the reaction intermediates treating 1 at reflux
in SOCl2 for different reaction times.
The overall proposed synthetic pathway is depicted in
Scheme 2. After 1 h the sulfonic acid 1 is transformed
into the halide 2 and only traces of unsaturated com-
pounds (Table 1; entry 1) are detectable. After 12 h and
treatment with ammonia the unsaturated sulfonamide
4 was recovered from the reaction mixture in 80% yield.
Moreover, 2-(4-Isobutylphenyl)-2-chloro-1-ethanesulfona-
mide 7 was isolated from the same reaction mixture
(entry 4).
In connection with our interest in Structure Activity
Relationships within the novel class of IL-8 inhibitors we
engaged the synthesis of R-substituted benzylsulfona-
mides (A) as potential new isosteres.4 It is a general
concern that R-alkylbenzylsulfonamides cannot be di-
rectly obtained from corresponding sulfonyl chlorides due
to the tendency of these intermediates to give, by rapid
desulfonylation, 1-phenyl-1-chloroalkanes. The formation
of 1-chloro-1-phenylethane from 1-phenyl-1-ethanesulfon-
ic acid by treatment with the chlorinating agent PCl5 was
described for the first time in 1938,5 but,up to date
detailed studies investigating the reactivity of these
compounds are not known.
To solve this synthetic problem an alternative “dianion”
based strategy has been set up6 but, actually, very few
examples of this class of molecules are known.7a-d,8a In
The formation of 4 and 7 accounts for the presence of
the corresponding intermediate sulfonyl chlorides 3 and
6. The mixture composition at intermediate times (entries
2 and 3) suggests that 6, formed on charge of 2, is the
key intermediate to 3. An E2 elimination pathway is in
agreement with the observed stereochemistry of 4.
Ammonia has been shown not to play a role in the
rearrangement to the final product. In fact, direct analy-
sis of the mixture before ammonia addition (t ) 8 h) has
(1) Chazalette, C.; Riviere-Baudet, M.; Supuran, C. T.; Scozzafava,
A. J . Enzyme Inhib. 2001, 16 (6), 475-89.
(2) Casini, A.; Scozzafava, A.; Mastrolorenzo, A.; Supuran, C. T.
Curr. Cancer Drug Targets 2002, 2 (1), 55-75.
(3) Bertini, R.; Bizzarri, C.; Sabbatini, W.; Porzio, S.; Caselli, G.;
Allegretti, M.; Cesta, M. C.; Gandolfi, C. A.; Mantovanini, M.; Colotta,
F. WO 00/24710, Oct 14, 1999.
(4) Nagai, T.; Shingaki, T.; Inagaki, M.; Ohshima, T. Bull. Chem.
Soc. J pn. 1979, 52 (4), 1102-1106.
(5) Kharasch, M. S.; May, E. M.; Mayo, F. R. J . Org. Chem. 1938,
3, 175-192.
(6) Thompson, M. E. J . Org. Chem. 1984, 49, 1700-1703.
(7) (a) Chazalette, C.; Riviere-Baudet, M.; Supuran, C. T.; Scoz-
zafava, A. J . Enzymol. Inhib. 2001, 16, 475-489. (b) Davis, A. F.; Zhou,
P. J . Org. Chem. 1993, 58, 4890-4896. (c) Nazarov, A. M.; Komissarov,
V. D.; Tolstikov, G. A. Zh. Org. Khim. 1991, 27 (4), 884-885. (d) Hartig,
S. J . Prakt. Chem. 1966, Band 33, 215-222.
(8) (a) Culbertson, B. M.; Dietz, S. J . Chem. Soc. (C) 1968, 992-
993. (b) Reddy Ramana, M. V.; Reddy, B. D.; Vijayalaskhmi, S.
Phosphorus, Sulfur Silicon Relat. Elem. 1990, 53, 285-290.
1
revealed, by GC-MS and H NMR analysis, the presence
of sulfonyl chloride intermediates 3 and 6 in the same
ratio as reported for the corresponding isolated amides
(Table 1; entry 3).
Our hypothesis is that 6 is formed through the styrene
intermediate 5, even if only traces of 5 are detectable at
any reaction time; the high reactivity of 5 could justify
the observed low yield. The conversion of 5 to 6, under
our reaction conditions, is not easily understandable. In
10.1021/jo034770f CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/03/2003
J . Org. Chem. 2003, 68, 7911-7914
7911

SCHEME 1
SCHEME 2
SCHEME 3. Syn th etic P a th w a y to
E-a r yleth en esu lfon a m id es
fact, as expected, reaction of 4-isobutylstyrene in thionyl
chloride does not afford the corresponding ethenesulfonyl
chloride. This observation suggests that a sulfur reactive
species is generated during the first reaction step on
charge of the sulfonic acid 1. The presence of sulfuryl
chloride (SO2Cl2) could account for the observed reactiv-
ity; in fact, the reaction of SO2Cl2 with styrenes is known
from the literature8a,b to lead to ethenesulfonyl chlorides
through an addition-elimination mechanism.
On the basis of these observations we hypothesize that
sulfur dioxide (SO2) formed during the first step is not
taken away from the mixture, but reacts with excess
SOCl2 to give either SO2Cl2 or another species with
similar reactivity. In agreement with this hypothesis the
intermediate 2, in the presence of only 1 equiv of SOCl2,
does not evolve.
From a practical point of view 1-(aryl)alkanesulfonic
acids cannot be considered suitable starting materials
due to their low availability and synthetic difficulties. On
7912 J . Org. Chem., Vol. 68, No. 20, 2003

SCHEME 4
TABLE 2. Rea ctivity of 1-Hyd r oxy-1-a r yla lk a n es to
attractive alternative method for the preparation of these
substrates currently largely employed in chemical and
pharmaceutical fields.
E-Ar yleth en esu lfon a m id es
entry
R
R1
R2, R3
yield (%)a
a
b
c
d
e
f
g
h
i
4-(CH3)2CHCH2
4-(CH3)2CHCH2
4-(CH3)2CHCH2
4-(CH3)2CHCH2
4-(CH3)2CHCH2 CH3
4-(CH3)2CHCH2 CH2CH3 H, H
H
H
H
H
H, H
80
75
78
68
75
67
70
70
58
8
H, CH2Ph
CH3, CH3
H, (CH2)3N(CH3)2
H, H
Exp er im en ta l Section
1-(4-Isobu tylph en yl)eth an esu lfon ic Acid (1). Sodium boro-
hydride (0.16 g, 4.26 mmol) was added portionwise to a stirred
solution of 4-isobutylacetophenone (0.5 g, 2.84 mmol) in metha-
nol (7 mL). After 1 h of refluxing, the mixture was cooled at
room temperature and 1 M HCl (5 mL) was added and the
solvent distilled off. The resulting aqueous acid phase was
extracted with EtOAc (3 × 5 mL) and the combined extract was
washed with brine (2 × 15 mL) and dried over Na2SO4. Removal
of the solvent under reduced pressure afforded the pure 1-hy-
droxy-1-(4-isobutylphenyl)ethane (0.495 g, 98%) as a colorless
oil: 1H NMR (CDCl3) δ 7.38 (d, 2H, J ) 7 Hz), 7.18 (d, 2H, J )
7 Hz), 4.95 (q, 1H, J ) 7 Hz), 4.52 (br s, 1H, OH), 2.50 (d, 2H,
J ) 7 Hz), 1.95 (m, 1H), 1.55 (d, 3H, J ) 7 Hz), 1.02 (d, 6H, J )
7 Hz); IR (neat, cm-1) ν 3345, 2980, 1500, 1380,1130; EI-MS m/z
178 (M+).
Treatment of 1-hydroxy-1-(4-isobutylphenyl)ethane (0.4 g,
2.24 mmol) with thiolacetic acid and zinc iodide was performed
as described.9 The crude was purified by column chromatography
(n-hexane/EtOAc 95:5) to give 1-[(4-isobutylphenyl)ethyl]thio-
acetate (0.43 g, 80%) as a yellow oil: 1H NMR (CDCl3) δ 7.35
(d, 2H, J ) 7 Hz), 7.20 (d, 2H, J ) 7 Hz), 4.75 (q, 1H, J ) 7 Hz),
2.50 (d, 2H, J ) 7 Hz), 2.35 (s, 3H), 1.85 (m, 1H), 1.65 (d, 3H, J
) 7 Hz), 0.95 (d, 6H, J ) 7 Hz); IR (neat, cm-1) ν 2900, 1700,
726, 628; EI-MS m/z 236 (M+).
H
H
H
H
H
H, H
H, H
H, H
H, H
H, H
3-(CH3)2CH
4-C6H5CH2
4-Cl
j
k
4-Br
CH3
a
Isolated yield.
the other hand, based on the described mechanistic
hypothesis, it is conceivable that 1-hydroxy-1-arylalkanes
should be useful synthetic equivalents because the same
intermediates, SO2 and 1-chloro-1-arylalkanes, are gen-
erated in the reaction with SOCl2. Hence, an optimized
procedure for the direct conversion of 1-hydroxy-1-ary-
lalkanes to E-arylethenesulfonamides has been set up.
The synthetic pathway is based on a simple one-pot, two-
step procedure and E-arylethenesulfonamides have been
obtained in good yields from readily available starting
materials (Scheme 3; Table 2).
Treatment of 1-[(4-isobutylphenyl)ethyl]thioacetate (0.36 g,
1.52 mmol) with 30% H2O2 and acetic acid was performed as
described10 to give 1 (0.38 g, 95%) isolated as sodium salt: 1H
NMR (DMSO-d6) δ 7.28 (d, 2H, J ) 7 Hz), 7.05 (d, 2H, J ) 7
Hz), 3.60 (q, 1H, J ) 7 Hz), 2.45 (d, 2H, J ) 7 Hz), 1.85 (m, 1H),
Looking at the results listed in Table 2, we can
conclude that the described procedure can be considered
a suitable process to prepare highly substituted styrene
derivatives in good yields starting from the corresponding
hydroxyalkanes. This procedure also seems to be an
attractive method for the synthesis of E-aryl ethene-
sulfonamides with the R1 group other than hydrogen
(entries e and f). Starting from the 4-bromo derivative
(entry k), the corresponding ethenesulfonamide is not
obtained; the main isolated reaction products, 1-chloro-
(4-bromophenyl)propane and 1-(4-bromo)-2-methylsty-
rene, do not evolve to the final addition products. An
unfavorable effect of electron-withdrawing groups on
double bond reactivity seems confirmed by the low
reactivity of the 4-chloro derivative (entry j).
In the Scheme 4 the behavior of branched 1-hydroxy-
1-arylalkanes in the same reaction conditions is depicted.
When R1 is tert-butyl (pathway a) only the formation of
tert-butylbenzyl chloride derivative 9 is, obviously, pos-
sible. Moreover, when R1 is isopropyl (pathway b), the
high percentage of recovered 1-(4-isobutyl)-2,2-dimeth-
ylstyrene 8 can be attributed to the unfavorable steric
effect of the methyl group on the addition to the double
bond.
1.47 (d, 3H, J ) 7 Hz), 0.90 (d, 6H, J ) 7 Hz); IR (Nujol, cm-1
)
ν 3400, 2950, 2750, 1220, 1200, 1170; EI-MS m/z 242 (M+)
(performed on isolated free acid).
An a lytica l Da ta for Com p ou n d s Listed in Ta ble 1. All
compounds listed in Table 1 have been obtained by purification
of the crude from 4 preparation by column chromatography with
n-hexane/EtOAc (gradient from 98:2 to 7:3) as eluent.
E-2-(4-Isobu tylp h en yl)eth en esu lfon a m id e (4) (Ta ble 2,
en tr y a ). 1 sodium salt (0.27 g, 1.03 mmol) was dissolved in
SOCl2 (5 mL, excess). The solution was refluxed overnight and
then cooled at room temperature. After SOCl2 removal in vacuo
the residue was diluted with dry THF (5 mL) and cooled at T )
0-5 °C in an ice/water bath. Ammonia (2 M solution in ethanol,
2.06 mmol) was added and the solution was left to rise to room
temperature. After 1 h solvents were evaporated in vacuo and
the residue was diluted with CHCl3 (10 mL) and washed with
water (2 × 10 mL). The organic layer was dried over Na2SO4.
Purification, according to the above-described procedure, af-
forded the product 4 as a pale yellow oil (0.20 g, yield 80%): 1H
NMR (CDCl3) δ 7.55 (d, 1H, J ) 14 Hz), 7.38 (d, 2H, J ) 7 Hz),
7.18 (d, 2H, J ) 7 Hz), 6.88 (d, 1H, J ) 14 Hz), 4.75 (br s, 2H,
SO2NH2), 2.55 (d, 2H, J ) 7 Hz), 1.94 (m, 1H), 1.02 (d, 6H, J )
7 Hz); IR (neat, cm-1) ν 3250, 2980, 1322, 1160; EI-MS m/z 239
(M+).
In conclusion we have described a straightforward, one-
pot, simple procedure for the synthesis of E-arylethene-
sulfonamides starting from 1-hydroxy-1-arylalkanes in
good yields. The easy availability of the starting materials
and the simple synthetic strategy make this process an
(9) Gauthier, J . Y.; Bourdon, F.; Young, R. N. Tetrahedron Lett.
1986, 27 (1), 15-18.
(10) Corey, E. J .; Cimprich, K. A. Tetrahedron Lett. 1992, 33 (29),
4099-4102.
J . Org. Chem, Vol. 68, No. 20, 2003 7913

1-Ch lor o-1-(4-isobu tylp h en yl)eth a n e (2): colorless oil; 1H
NMR (CDCl3) δ 7.25 (d, 2H, J ) 7 Hz), 7.05 (d, 2H, J ) 7 Hz),
5.05 (q, 1H, J ) 7 Hz), 2.42 (d, 2H, J ) 7 Hz), 1.80 (m, 1H, d,
3H, J ) 7 Hz), 0.85 (d, 6H, J ) 7 Hz); EI-MS m/z 196/198 ([35/37Cl]
M+).
75%; 1H NMR (CDCl3) δ 7.60 (s, 1H), 7.32 (d, 2H, J ) 7 Hz),
7.15 (d, 2H, J ) 7 Hz), 4.56 (br s, 2H, SO2NH2), 2.50 (d, 2H, J
) 7 Hz), 2.35 (s, 3H), 1.88 (m, 1H), 0.97 (d, 6H, J ) 7 Hz); IR
(neat, cm-1) ν 3300, 3250, 2950, 1322, 1159; EI-MS m/z 253 (M+).
E-2-(4-Isobu tylp h en yl)-1-eth yleth en esu lfon a m id e (en tr y
f): yellow oil (eluent mixture: n-hexane/EtOAc 7:3); yield 67%;
1H NMR (CDCl3) δ 7.58 (s, 1H), 7.30 (d, 2H, J ) 7 Hz), 7.18 (d,
2H, J ) 7 Hz), 4.60 (br s, 2H, SO2NH2), 2.55 (d, 2H, J ) 7 Hz),
2.45 (q, 2H, J ) 8 Hz), 1.90 (m, 1H), 1.10 (t, 3H, J ) 8 Hz), 0.97
(d, 6H, J ) 7 Hz); IR (neat, cm-1) ν 3260, 2950, 1322, 1159; EI-
MS m/z 267 (M+).
4-Isobu tylstyr en e (5): colorless oil; 1H NMR (CDCl3) δ 7.30
(d, 2H, J ) 7 Hz), 7.10 (d, 2H, J ) 7 Hz), 6.75 (d, 1H, J ) 12
Hz), 6.50 (d, 2H, J ) 12 Hz), 2.40 (d, 2H, J ) 7 Hz), 1.80 (m,
1H), 0.85 (d, 6H, J ) 7 Hz); EI-MS m/z 160 (M+).
2-(4-Isob u t ylp h e n yl)-2-ch lor o-1-e t h a n e su lfon a m id e
1
(7): yellow oil; H NMR (CDCl3) δ 7.35 (d, 2H, J ) 7 Hz), 7.18
(d, 2H, J ) 7 Hz), 5.20 (t, 1H, J ) 7 Hz), 4.50 (br s, 2H, SO2NH2),
4.15 (d, 2H, J ) 7 Hz), 2.35 (d, 2H, J ) 7 Hz), 1.65 (m, 1H), 0.90
(d, 6H, J ) 7 Hz); EI-MS m/z 275/277 ([35/37Cl] M+).
E-2-P h en yleth en esu lfon a m id e (en tr y g): yellow oil (elu-
ent mixture: n-hexane/EtOAc 7:3); yield 70%; 1H NMR (CDCl3)
δ 7.55 (d, 1H, J ) 13 Hz), 7.35 (m, 5H), 6.85 (d, 1H, J ) 13 Hz),
4.72 (br s, 2H, SO2NH2); IR (neat, cm-1) ν 3250, 2970, 1330, 1160;
EI-MS m/z 183 (M+).
E-2-(3-Isop r op ylp h en yl)et h en esu lfon a m id e (en t r y h ):
yellow oil (eluent mixture: n-hexane/EtOAc 7:3); yield 70%; 1H
NMR (CDCl3) δ 7.50 (d, 1H, J ) 13 Hz), 7.20 (d, 1H, J ) 7 Hz),
7.10 (m, 3H), 6.80 (d, 1H, J ) 13 Hz), 4.72 (br s, 2H, SO2NH2),
2.90 (m, 1H), 1.02 (d, 6H, J ) 7 Hz); IR (neat, cm-1) ν 3220,
2910, 1340, 1110; EI-MS m/z 225 (M+).
E-2-(4-Ben zylp h en yl)eth en esu lfon a m id e (en tr y i): yel-
low oil (eluent mixture: n-hexane/EtOAc 8:2); yield 58%; 1H
NMR (CDCl3) δ 7.55 (d, 1H, J ) 13 Hz), 7.35-7.10 (m, 9H), 6.80
(d, 1H, J ) 13 Hz), 4.72 (br s, 2H, SO2NH2), 3.98 (s, 2H); IR
(neat, cm-1) ν 3300, 2900, 1290, 1160; EI-MS m/z 273 (M+).
E-2-(4-Ch lor op h en yl)eth en esu lfon a m id e (en tr y j): yel-
low oil (eluent mixture: n-hexane/EtOAc 7:3); yield 8%; 1H NMR
(CDCl3) δ 7.60 (d, 1H, J ) 13 Hz); 7.30-7.20 (m, 4H), 6.65 (d,
1H, J ) 13 Hz), 4.75 (br s, 2H, SO2NH2); IR (neat, cm-1) ν 3300,
2970, 1330, 1160; EI-MS m/z 217/219 ([35/37Cl] M+).
An a lytica l Da ta for Com p ou n d s in Sch em e 4. 1-(4-
Isobu tyl)-2,2-d im eth ylstyr en e (8): colorless oil (eluent mix-
ture: n-hexane/EtOAc 95:5); yield 80%; 1H NMR (CDCl3) δ 7.05
(m, 4H), 6.15 (s, 1H), 2.40 (d, 2H, J ) 7 Hz), 1.80 (d, 6H, J ) 7
Hz + m, 1H), 0.85 (d, 6H, J ) 7 Hz); EI-MS m/z 188 (M+).
1-(4-Isobu tylp h en yl)-1-ch lor o-2,2-d im eth ylp r op a n e (9):
colorless oil (eluent mixture: n-hexane/EtOAc 95:5); yield 80%;
1H NMR (CDCl3) δ 7.30 (d, 2H, J ) 7 Hz), 7.12 (d, 2H, J ) 7
Hz), 5.35 (s, 1H), 2.52 (d, 2H, J ) 7 Hz), 1.95 (m, 1H), 1.08 (s,
9H), 0.95 (d, 6H, J ) 7 Hz); EI-MS m/z 238/240 ([35/37Cl] M+).
Gen er a l P r oced u r e for P r ep a r a tion of E-Ar yleth en e-
su lfon a m id es (Ta ble 2). 1-Hydroxy-1-arylalkane (1.03 mmol)
was dissolved in SOCl2 (5 mL, excess). The solution was refluxed
overnight and then cooled at room temperature. SOCl2 was
removed in vacuo, and the residue was diluted with dry THF (5
mL) and cooled at T ) 0-5 °C in an ice/water bath. The selected
amine (2.06 mmol) was added and the solution was allowed to
rise to room temperature. After 1 h solvents were evaporated
in vacuo and the residue diluted with CHCl3 (10 mL), washed
with water (2 × 10 mL), and dried over Na2SO4. Solvent removal
under reduced pressure afforded a crude residue purified by flash
chromatography to give pure products characterized by NMR,
IR, and MS analysis.
E-2-(4-Isobu tylp h en yl)eth en e-N-ben zylsu lfon a m id e (en -
tr y b): white solid (eluent mixture: n-hexane/EtOAc 7:3); mp
1
118-121 °C; yield 75%; H NMR (CDCl3) δ 7.40 (d, 1H, J ) 14
Hz), 7.25 (d, 2H, J ) 7 Hz), 7.10 (d, 2H, J ) 7 Hz), 6.58 (d, 1H,
J ) 14 Hz), 4.45 (br s, 1H, SO2NH), 4.20 (d, 2H, J ) 5 Hz), 2.45
(d, 2H, J ) 7 Hz), 1.80 (m, 1H), 0.85 (d, 6H, J ) 7 Hz); IR (Nujol,
cm-1) ν 3415, 2950, 1150, 1322; EI-MS m/z 329 (M+).
E -2-(4-Isob u t ylp h e n yl)e t h e n e -N ,N -d im e t h ylsu lfon a -
m id e (en tr y c): yellow oil (eluent mixture: n-hexane/EtOAc
1
8:2); yield 78%; H NMR (CDCl3) δ 7.45 (m, 3H), 7.21 (d, 2H, J
) 7 Hz), 6.65 (d, 1H, J ) 14 Hz), 2.85 (s, 6H), 2.55 (d, 2H, J )
7 Hz), 1.90 (m, 1H), 0.92 (d, 6H, J ) 7 Hz); IR (neat, cm-1) ν
3400, 2950, 1180, 990, 780; EI-MS m/z 267 (M+).
E-2-(4-Isobu tylph en yl)eth en e-N-[3-(N,N-dim eth ylam in o)-
p r op yl]su lfon a m id e (en tr y d ): yellow oil (eluent mixture: 5%
1
TEA in CHCl3/CH3OH 8:2); yield 68%; H NMR (CDCl3) δ 7.45
(m, 3H), 7.20 (d, 2H, J ) 7 Hz), 6.70 (d, 1H, J ) 14 Hz), 3.18 (m,
2H), 2.50 (d, 2H, J ) 5 Hz), 2.45 (m, 2H + SO2NH), 2.30 (s, 6H),
1.92 (m, 1H), 1.75 (m, 2H), 0.92 (d, 6H, J ) 7 Hz); IR (neat,
cm-1) ν 3414, 2900, 1148, 780; EI-MS m/z 324 (M+).
E-2-(4-Isobu tylp h en yl)-1-m eth yleth en esu lfon a m id e (en -
tr y e): yellow oil (eluent mixture: n-hexane/EtOAc 8:2); yield
Su p p or tin g In for m a tion Ava ila ble: Elemental analysis
data of all new compounds. This material is available free of
charge via the Internet at http://pubs.acs.org.
J O034770F
7914 J . Org. Chem., Vol. 68, No. 20, 2003