Rauhut-currier reaction of nitroalkenes with vinyl sulfones

Article abstract of DOI:10.1021/jo400528j

The Rauhut-Currier reaction between nitroalkenes and vinyl sulfones has been successfully carried out for the first time. The reaction proceeds in the presence of an imidazole/LiCl catalyst system in dioxane to provide the adducts possessing a synthetically useful 1-bis-sulfonyl-3-nitroalkene moiety in good to excellent yield. A one-pot transformation of the products to β-sulfonyl-α,β-unsaturated ketoximes has also been demonstrated.

Full text of DOI:10.1021/jo400528j

Note
pubs.acs.org/joc
Rauhut−Currier Reaction of Nitroalkenes with Vinyl Sulfones
Rahul Kumar,† Tarun Kumar,† Shaikh M. Mobin,‡ and Irishi N. N. Nambothiri*,†
†Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India
‡Discipline of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore, Indore 452 017, India
S
* Supporting Information
ABSTRACT: The Rauhut−Currier reaction between nitroalkenes
and vinyl sulfones has been successfully carried out for the first time.
The reaction proceeds in the presence of an imidazole/LiCl catalyst
system in dioxane to provide the adducts possessing a synthetically
useful 1-bis-sulfonyl-3-nitroalkene moiety in good to excellent yield. A
one-pot transformation of the products to β-sulfonyl-α,β-unsaturated
ketoximes has also been demonstrated.
a
Table 1. Optimization of the Reaction Conditions
he Morita−Baylis−Hillman (MBH) reaction has emerged
as an efficient method for α-functionalization of activated
T
alkenes with various electrophiles such as aldehydes, imines,
etc. in the presence of an amine or phosphine catalyst.1
However, dimerization of the substrate in the absence of an
electrophile was reported by Rauhut and Currier,2 prior to the
MBH reaction, but was overshadowed by the enormous scope
and applicability of the latter. Nevertheless, the Rauhut−
Currier (RC) dimerizations of activated alkenes such as
acrylonitrile,3,4 vinyl ketones,5,6 acrylates,4,6 and vinyl sulfone
and vinyl sulfonate6 have been reported. The scope of the
reaction was further expanded by cross-coupling of different
activated alkenes7 and by developing intramolecular and
asymmetric versions.8 Applications of the RC reaction as the
key step in natural product synthesis have also been
investigated.9
In recent years, nitroalkenes have been employed as
substrates in the MBH10 and the RC11−14 reactions.15 The
RC cross-coupling of nitroalkenes with azodicarboxylates,11
methyl vinyl ketone,12,13 and acrylate12,14 afforded synthetically
useful multifunctional adducts.15 The RC dimerization of
nitroalkenes and nitrodienes proceeded in low to moderate
yield in the presence of imidazole and hydroquinone.13
However, the RC cross-coupling of nitroalkenes with vinyl
sulfones remained unreported hitherto.
From another perspective, organosulfones exhibit a variety of
biological properties, for instance, the antiprostate cancer drug
Bicalutamide and the antileprosy drug Dapsone contain a
sulfonyl group. Although similar biological and synthetic
applications of sulfones have been extensively investigated,16
the reactivity of vinyl bis-sulfones, in particular, as Michael
acceptors has not received sufficient attention.17 Herein, we
report a high-yielding RC coupling of nitroalkenes and
nitrodienes with vinyl bis-sulfones in the presence of an
imidazole/LiCl catalyst system.
additive
(equiv)
time
(h)
b
entry catalyst (equiv)
solvent
% yield
1
DABCO (1)
DMAP (1)
THF
48
24
16
15
15
14
14
12
13
12
12
24
c
d
2
CH3CN
THF
20
d
3
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (1)
imidazole (0.5)
44
d
4
ether
33
d
5
acetone
EtOAc
dioxane
THF
35
6
58
50
60
63
88
81
83
7
8
LiCl (1)
LiCl (1)
LiCl (1)
LiCl (0.5)
9
EtOAc
dioxane
dioxane
dioxane
10
11
12
LiCl (1)
a
b
1a and 2a were used in 2:1 ratio. Isolated yield after purification by
c
d
silica gel chromatography. No reaction. Substantial quantity of 1a
was recovered and 2a polymerized.
after 24 h, imidazole-catalyzed reactions in different solvents
were much superior, and the product 3a was isolated in much
higher yield (33−58%) in shorter reaction time (14−24 h,
entries 3−7). Finally, we explored the possibility of using LiCl
as a salting out agent and a weak Lewis acid.12 This improved
the yields only marginally (60−63%) in solvents such as THF
and EtOAc (12−13 h, entries 8 and 9). However, complete
conversion in 12 h with remarkable increase in the yield (88%)
was observed when dioxane was used as the solvent (entry 10).
Imidazole and LiCl in stoichiometric amounts were necessary
to obtain the best yield in the shortest possible time (entry 10).
While lowering the quantity of LiCl led to a drop in the yield,
Initially, we screened the classical MBH catalyst DABCO for
the model reaction of nitroalkene 1a with sulfone 2a, which led
to no conversion even after 48 h (Table 1, entry 1). While
DMAP in CH3CN gave the product 3a in 20% yield (entry 2)
Received: March 13, 2013
© XXXX American Chemical Society
A
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The Journal of Organic Chemistry
Note
though marginal (81%, entry 11), a decrease in reaction rate
with marginal decrease in the yield was observed upon lowering
the quantity of imidazole (24 h, 83%, entry 12). It appears that
the solvation of LiCl is minimized as the dielectric constant of
the solvent decreases (ε: THF 7.52, EtOAc 6.08, dioxane 2.22)
resulting in substantial improvement in the yield (entries 8−
10).
The above optimized conditions were employed to
investigate the scope of the reaction by screening different
nitroalkenes 1 (Table 2). Thus nitroalkenes 1a−e with
Figure 1. Structure and stereochemical assignment of 3 by NMR.
1
was evident from the H−1H NOESY spectrum of 3n. First of
1
all, the three olefinic protons in 3n were assigned by H−1H
a
Table 2. Scope of the Reaction
COSY experiment. While H2 appeared as a dd at δ 7.19, H1
overlapped with aromatic protons in the range δ 7.67−7.75,
and H3, the 1H β to the nitro group, overlapped with aromatic
protons in the range δ 7.82−7.89. Since H1 and H3 are very
close in terms of chemical shifts and the corresponding signals
overlap with the aromatic protons, their NOE cross peaks are
not very diagnostic. However, the presence of strong NOE for
H2 with H5 and H6 and a J value of 15.1 and 11.7 Hz for H2
supported the above assignment. The double bond geometry in
b
entry
R
3
time (h)
% yield
1
4-OMeC6H4
3,4-(OMe)2C6H3
benzo[d][1,3]dioxole
4-NMe2C6H4
4-MeC6H4
3a
3b
3c
3d
3e
3f
12
13
15
12
14
14
18
20
12
18
13
13
15
17
15
15
88
85
82
72
78
68
60
57
72
61
80
86
75
83
61
62
2
3
1
RC adducts 3o−p was also determined by H−1H NOESY
4
analysis. The absence of any NOE for H4 with H2 or H1
together with the presence of medium NOE for cyclohexyl
protons with H2 and H1 confirmed the E geometry in 3o. This
assignment was unambiguously established by single crystal X-
ray analysis of a representative compound 3n (see the
Experimental Section and the Supporting Information).
5
6
C6H5
7
3-BrC6H4
3g
3h
3i
8
2-ClC6H4
9
4-FC6H4
10
11
12
13
14
15
16
4-NO2C6H4
2-furyl
3j
The proposed role of imidazole and LiCl in mediating the
RC reaction of nitroalkenes 1 with vinyl sulfone 2a is outlined
in Scheme 2. The initial conjugate addition of imidazole, a
3k
3l
2-thienyl
C6H5CHCH
2-NO2C6H4CHCH
cyclohexyl
3m
3n
3o
3p
Scheme 2. Proposed Mechanism for the Imidazole/LiCl
Mediated Rauhut−Currier Reaction
CH3(CH2)3
a
Carried out at 0.5 mmol scale of sulfone 2a with 2 equiv of
b
nitroalkene 1 and 1 equiv each of imidazole and LiCl. Isolated yield
after purification by silica gel chromatography.
electron-donating substituents on the aromatic ring provided
the RC adducts 3a−e in high yield (72−88%, entries 1−5).
The yields were lower (60−72%) with nitrostyrene 1f and
nitroalkenes 1g−j possessing weakly and strongly deactivating
substituents on the aromatic ring (entries 6−10). The RC
adducts 3k−l were isolated in excellent yield (80−86%) when
heteroaromatic nitroalkenes 1k−l were reacted with sulfone 2a
(entries 11 and 12). While the yields of RC adducts 3m−n
were high (75−83%) with nitrodienes 1m−n (entries 13 and
14), aliphatic nitroalkenes 1o−p afforded the products 3o−p in
lower yield (61−62%, entries 15 and 16).
nucleophilic Lewis base, is facilitated and the reversibility of the
reaction is minimized by co-ordination of the nitro group with
LiCl, a weak Lewis acid. This stabilized nitronate I then adds in
a Michael fashion to vinyl sulfone 2a which is also activated by
LiCl to generate intermediate II. The β-elimination of
imidazole from II, triggered by the γ-hydrogen abstraction by
the alkanesulfonyl group, completes the reaction to deliver the
RC adduct 3.
Having developed an efficient method for the coupling of
nitroalkenes 1 with vinyl sulfones 2 under the RC conditions,
we sought to investigate the possible applications of the RC
adducts 3. Thus, representative RC adducts 3e and 3i were
subjected to metal/acid reduction under standard conditions
(Scheme 3). Much to our amusement, the nitro group
reduction stopped at the oxime stage, and elimination of one
of the sulfonyl groups took place, all in one pot, to afford β-
sulfonyl α,β-unsaturated oximes 5e and 5i in satisfactory yield
Under the above conditions, the reaction of a representative
nitroalkene 1a with vinyl sulfone 2b afforded the desired
product 4 in only low yield (25%, Scheme 1).
The structure and stereochemistry of RC adducts 3 were
established by extensive NMR analysis (Figure 1). Appearance
of the 1H β to the nitro group in the RC adducts 3a−l and 4 in
the range of 7.90−8.30 confirmed that the geometry of the
double bond is E. The E,E geometry in the RC adducts 3m−n
Scheme 1
B
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Note
mg); mp 176−178 °C; IR (KBr, cm−1) 3225 (w), 2923 (w), 1645 (m),
Scheme 3
1556 (w), 1520 (s), 1448 (m), 1331 (m), 1314 (m), 1268 (s), 1245
1
(m), 1148 (s), 1079 (w), 1021 (m), 737 (m); H NMR (400 MHz,
CDCl3) δ 3.85 (d, J = 7.4 Hz, 2H), 3.94 (s, 3H), 3.95 (s, 3H), 5.25 (t,
J = 7.4 Hz, 1H), 6.94 (d, J = 8.4 Hz, 1H), 7.16 (dd, J = 8.4, 1.2 Hz,
1H), 7.36 (d, J = 1.2 Hz, 1H), 7.51 (t, J = 7.6 Hz, 4H), 7.68 (t, J = 7.6
Hz, 2H), 7.81 (d, J = 7.6 Hz, 4H), 8.11 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 24.93, 56.19, 56.52, 78.95, 111.41, 112.41, 123.66, 125.69,
129.38 (×2), 134.97, 137.93, 138.47, 142.75, 149.65, 151.82; MS (ES
+, Ar) m/z (rel intensity) 540 (MNa+, 100), 519 ([M + 2]+, 20), 518
(M+, 50); HRMS (ES+, Ar) calcd for C24H24NO8S2 (MH+) 518.0943,
found 518.0942.
(E)-5-(2-Nitro-4,4-bis(phenylsulfonyl)but-1-enyl)benzo[d]-
[1,3]dioxole (3c). Yellow solid; yield 82% (205 mg); mp 184−186
°C; IR (KBr, cm−1) 3231 (w), 3066 (w), 2918 (w), 1643 (vs), 1504
(w), 1487 (w), 1449 (m), 1334 (s), 1311 (m), 1262 (m), 1157 (m),
(48−50%) as an inseparable mixture of syn/anti or anti/syn
isomers in 86:14 to 89:11 ratio. The plausible mechanism for
the transformation of the RC adduct 3 to oxime 5 involves
formation of hydroxylamine III, its tautomerization to oxime
IV, and elimination of benzenesulfinic acid from IV. The J
values for the olefinic protons in anti and syn isomers were in
the same range (15.5−15.9), as expected, indicating E geometry
for the double bond in 5, which was further confirmed by NOE
experiment. A moderate NOE between CH2 and the proton β
to the oxime group confirmed this assignment.
In conclusion, cross-coupling of nitroalkenes with vinyl
sulfone has been carried out for the first time under the
Rauhut−Currier conditions to afford the adducts in good to
excellent yield in most cases. While vinyl bis-sulfones are good
coupling partners, vinyl monosulfones were less efficient. A
one-pot nitro group reduction−sulfone elimination under
metal-acid conditions delivered synthetically useful β-sulfonyl
α,β-unsaturated oximes in satisfactory yield and >85:15 anti/syn
selectivity.
1
1037 (m), 741 (m); H NMR (400 MHz, CDCl3) δ 3.81 (d, J = 7.3
Hz, 2H), 5.17 (t, J = 7.3 Hz, 1H), 6.08 (s, 2H), 6.90 (d, J = 8.0 Hz,
1H), 7.08−7.11 (m, 2H), 7.50−7.54 (m, 4H), 7.68 (tt, J = 6.4, 1.1 Hz,
2H), 7.82 (dd, J = 8.4, 1.1 Hz, 4H), 8.14 (s, 1H); 13C NMR (100
MHz, CDCl3) δ 24.49, 79.20, 102.18, 109.33, 109.82, 124.96, 126.72,
129.41, 129.51, 135.02, 137.81, 138.08, 143.42, 148.80, 150.35; MS
(ES+, Ar) m/z (rel intensity) 524 (MNa+, 40), 503 ([M + 2]+, 9), 502
(MH+, 35), 496 (56), 480 (38), 458 (93), 456 (100); HRMS (ES+,
Ar) calcd for C23H20NO8S2 (MH+) 502.0630, found 502.0639.
(E)-N,N-Dimethyl-4-(2-nitro-4,4-bis(phenylsulfonyl)but-1-
enyl)aniline (3d). Yellow solid; yield 72% (180 mg); mp 190−192
°C; IR (KBr, cm−1) 3065 (w), 2925 (w), 1668 (w), 1598 (s), 1531
(w), 1448 (w), 1332 (s), 1311 (s), 1292 (m), 1159 (vs), 1078 (m),
749 (m), 732 (m); 1H NMR (400 MHz, CDCl3) δ 3.10 (s, 6H), 3.91
(d, J = 7.2 Hz, 2H), 5.27 (t, J = 7.2 Hz, 1H), 6.73 (d, J = 8.9 Hz, 2H),
7.50 (t, J = 7.6 Hz, 4H), 7.56 (d, J = 8.9 Hz, 2H), 7.66 (t, J = 7.6 Hz,
2H), 7.82−7.84 (m, 4H), 8.04 (s, 1H); 13C NMR (100 MHz, CDCl3)
δ 24.98, 40.21, 79.11, 112.20, 117.88, 129.34, 129.41, 133.83, 134.83,
138.37, 138.80, 139.62, 152.51; MS (ES+, Ar) m/z (rel intensity) 523
(MNa+, 15), 502 ([MH + 1]+, 24), 501 (MH+, 80), 444 (22), 379
(33), 363 (100), 341 (52); HRMS (ES+, Ar) calcd for C24H25N2O6S2
(MH+) 501.1154, found 501.1169.
1-((E)-3-Nitro-1-(phenylsulfonyl)-4-p-tolylbut-3-
enylsulfonyl)benzene (3e). Yellow solid; yield 78% (184 mg); mp
156−158 °C; IR (KBr, cm−1) 3225 (w), 3055 (w), 1650 (vs), 1604
(s), 1517 (w), 1505 (w), 1443 (w), 1328 (s), 1310 (vs), 1279 (m),
1156 (m), 1080 (w), 742 (m); 1H NMR (400 MHz, CDCl3) δ 2.44 (s,
3H), 3.81 (d, J = 7.2 Hz, 2H), 5.14 (t, J = 7.2 Hz, 1H), 7.29 (d, J = 8.0
Hz, 2H), 7.44 (d, J = 8.0 Hz, 2H), 7.47−7.51 (m, 4H), 7.65−7.69 (m,
2H), 7.78 (dd, J = 8.4, 1.1 Hz, 4H), 8.14 (s, 1H); 13C NMR (100
MHz, CDCl3) δ 21.72, 24.26, 79.23, 128.31, 129.34, 129.47, 130.21,
130.34, 134.95, 137.65, 138.09, 141.69, 144.33; MS (ES+, Ar) m/z (rel
intensity) 494 (MNa+, 10), 489 (16), 474 ([MH + 2]+, 13), 473 ([MH
+ 1]+, 29), 472 (MH+, 100); HRMS (ES+, Ar) calcd for C23H22NO6S2
(MH+) 472.0889, found 472.0887.
1-((E)-3-Nitro-4-phenyl-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3f). Yellow solid; yield 68% (156 mg); mp
174−176 °C; IR (KBr, cm−1) 3065 (w), 2930 (w), 1648 (m), 1558
(m), 1525 (s), 1448 (m), 1333 (vs), 1264 (m), 1157 (vs), 1079 (m),
737 (s); 1H NMR (400 MHz, CDCl3) δ 3.78 (d, J = 7.2 Hz, 2H), 5.13
(t, J = 7.2 Hz, 1H), 7.47−7.54 (m, 9H), 7.67 (t, J = 7.5 Hz, 2H), 7.77
(dd, J = 8.4, 1.1 Hz, 4H), 8.19 (s, 1H); 13C NMR (100 MHz, CDCl3)
δ 24.21, 79.32, 129.38, 129.49, 129.53, 130.08, 130.84, 131.32, 135.00,
137.55, 137.86, 145.32; MS (ES+, Ar) m/z (rel intensity) 480 (MNa+,
7), 475 (12), 460 ([MH + 2]+, 14), 459 ([MH + 1]+, 29), 458 (MH+,
100); HRMS (ES+, Ar) calcd for C22H20NO6S2 (MH+) 458.0732,
found 458.0746.
1-(E)-4-(3-Bromophenyl)-3-nitro-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3g). Yellow solid; yield 60% (161 mg); mp
122−124 °C; IR (KBr, cm−1) 3065 (w), 2927 (w), 1653 (m), 1525
(s), 1448 (m), 1334 (vs), 1287 (m), 1156 (s), 1078 (s), 737 (s), 685
(s); 1H NMR (400 MHz, CDCl3) δ 3.72 (d, J = 7.2 Hz, 2H), 5.12 (t, J
= 7.2 Hz, 1H), 7.34 (t, J = 7.8 Hz, 1H), 7.48−7.52 (m, 5H), 7.60 (d, J
= 8.2 Hz, 1H), 7.63 (d, J = 0.8 Hz, 1H), 7.67 (td, J = 8.3, 0.8, 2H),
EXPERIMENTAL SECTION
■
General. The melting points recorded are uncorrected. NMR
1
1
1
spectra (1H, H decoupled 13C, 13C-APT, H−1H COSY, and H−1H
NOESY) were recorded with TMS as the internal standard. The
coupling constants (J values) are given in hertz. High resolution mass
spectra were recorded under ESI Q-TOF conditions. X-ray data were
collected on a diffractometer equipped with graphite monochromated
Mo Kα radiation. The structure was solved by direct methods shelxs97
and refined by full-matrix least-squares against F2 using shelxl97
software.
General Procedure for the Rauhut−Currier Reaction. To a
stirred solution of nitroalkene 1 (1 mmol) and vinyl sulfone 2 (0.5
mmol) in dioxane (5 mL) were added imidazole (34 mg, 0.5 mmol)
and LiCl (21 mg, 0.5 mmol), and the resulting mixture was stirred
until the completion of the reaction (monitored by TLC). Then the
reaction mixture was concentrated in vacuo, and the crude residue was
directly subjected to silica gel column chromatography (60−120 mesh,
n-hexane/ethyl acetate, 40:60) to afford pure products 3.
1-((E)-4-(4-Methoxyphenyl)-3-nitro-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3a). Yellow solid; yield 88% (214 mg); mp
158−160 °C; IR (KBr, cm−1) 3209 (w), 2923 (w), 1644 (m), 1603
(s), 1520 (s), 1448 (m), 1334 (s), 1309 (s), 1262 (s), 1177 (s), 1156
(s), 1079 (m), 736 (s); 1H NMR (400 MHz, CDCl3) δ 3.84 (d, J = 7.0
Hz, 2H), 3.89 (s, 3H), 5.18 (t, J = 7.0 Hz, 1H), 7.00 (d, J = 8.8 Hz,
2H), 7.49−7.53 (m, 4H), 7.56 (d, J = 8.8 Hz, 2H), 7.66−7.70 (m,
2H), 7.80−7.82 (m, 4H), 8.12 (s, 1H); 13C NMR (100 MHz, CDCl3)
δ 24.46, 55.66, 79.10, 115.02, 123.33, 129.36, 129.41, 132.70, 134.95,
137.78, 138.02, 142.77, 162.02; MS (ES+, Ar) m/z (rel intensity) 510
(MNa+, 31), 505 (29), 489 ([MH + 1]+, 7), 488 (MH+, 31), 444 (13),
443 (24), 442 (100); HRMS (ES+, Ar) calcd for C23H22NO7S2 (MH+)
488.0838, found 488.0827.
1-((E)-4-(3,4-Dimethoxyphenyl)-3-nitro-1-(phenylsulfonyl)-
but-3-enylsulfonyl)benzene (3b). Yellow solid; yield 85% (220
C
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The Journal of Organic Chemistry
Note
7.77 (dd, J = 8.3, 0.8 Hz, 4H), 8.08 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 24.22, 79.22, 123.33, 128.14, 129.41, 129.47, 130.94, 132.66,
133.33, 133.57, 135.08, 136.10, 137.39, 146.36; MS (ES+, Ar) m/z (rel
intensity) 538 ([MH + 2]+, 23), 537 ([MH + 1]+, 100), 536 (MH+,
65); HRMS (ES+, Ar) calcd for C22H19NO6S2Br (MH+) 535.9837,
found 535.9855.
1-((E)-4-(2-Chlorophenyl)-3-nitro-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3h). Yellow liquid; yield 57% (140 mg); IR
(neat, cm−1) 3063 (w), 2929 (w), 1657 (m), 1559 (w), 1528 (s), 1473
(w), 1447 (w), 1340 (vs), 1266 (w), 1157 (s), 1078 (m), 753 (s); 1H
NMR (400 MHz, CDCl3) δ 3.68 (d, J = 7.3 Hz, 2H), 5.14 (t, J = 7.3
Hz, 1H), 7.49−7.55 (m, 4H), 7.66−7.75 (m, 4H), 7.75−7.80 (m, 4H),
8.30 (s, 1H), 8.31 (d, J = 8.4 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ
24.13, 79.30, 127.59, 129.36, 129.42, 129.51, 129.71, 130.19, 130.25,
131.64, 134.85, 134.99, 137.43, 146.83; MS (ES+, Ar) m/z (rel
intensity) 494 ([MH + 2]+, 40), 493 ([MH + 1]+, 25), 492 (MH+,
100), 297 (17); HRMS (ES+, Ar) calcd for C22H19NO6S2Cl 492.0342,
found 492.0337.
1328 (s), 1306 (s), 1163 (s), 1148 (vs), 1079 (m), 754 (s), 733 (s);
1H NMR (400 MHz, CDCl3) δ 3.70 (d, J = 6.9 Hz, 2H), 5.12 (t, J =
6.9 Hz, 1H), 7.18 (ABq, J = 15.2 Hz, 2H), 7.40−7.45 (m, 3H), 7.52−
7.56 (m, 4H), 7.57−7.60 (m, 2H), 7.69 (tt, J = 6.9, 1.1 Hz, 2H), 7.84
(dd, J = 8.5, 2.5 Hz, 1H), 7.87 (dd, J = 8.4, 1.1 Hz, 4H); 13C NMR
(100 MHz, CDCl3) δ 24.17, 79.48, 121.21, 128.37, 129.25, 129.37,
129.47, 130.78, 135.02, 135.49, 138.13, 138.90, 142.59, 147.45; MS
(ES+, Ar) m/z (rel intensity) 486 ([MH + 2]+, 13), 485 ([MH + 1]+,
27), 484 (MH+, 100), 296 (15); HRMS (ES+, Ar) calcd for
C24H22NO6S2 (MH+) 484.0889, found 484.0874.
1-Nitro-2-((1E,3E)-4-nitro-6,6-bis(phenylsulfonyl)hexa-1,3-
dienyl)benzene (3n). Yellow solid; yield 83% (219 mg); mp 120−
122 °C; IR (KBr, cm−1) 3155 (m), 2988 (m), 1727 (w), 1618 (w),
1528 (s), 1446 (m), 1350 (s), 1244 (s), 1023 (vs), 982 (s), 785 (m),
737 (s); 1H NMR (400 MHz, CDCl3) δ 3.71 (d, J = 6.9 Hz, 2H), 5.10
(t, J = 6.9 Hz, 1H), 7.19 (dd, J = 15.1, 11.7 Hz, 1H), 7.52−7.58 (m,
5H), 7.67−7.75 (m, 4H), 7.82−7.89 (m, 6H), 8.06 (dd, J = 8.2, 1.0
Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 24.25, 79.23, 125.23,
125.99, 129.27, 129.57, 129.90, 130.53, 131.33, 134.04, 135.12, 137.72,
138.19, 141.25, 144.45, 148.17; MS (ES+, Ar) m/z (rel intensity) 531
([MH + 2]+, 15), 530 ([MH + 1]+, 28), 529 (MH+, 100); HRMS (ES
+, Ar) calcd for C24H21N2O8S2 (MH+) 529.0739, found 529.0765;
C52H48N4O18S4, M = 1145.18, Orthorhombic, space group Pna21, a =
13.2930 (3) Å, b = 11.5155 (3) Å, c = 34.5292 (9) Å, α = 90°, β = 90°,
γ = 90°, V = 5285.6 (2) Å3, Dc = 1.439 Mg/m3, Z = 4, F(000) = 2384,
λ = 0.71073 Å, μ = 0.259 mm−1, total/unique reflections = 46996/
9252 [R(int) = 0.0497], T = 150(2) K, θ range = 3.12−24.98°, final R
[I > 2σ(I)]: R1= 0.0486, wR2 = 0.1185; R (all data): R1 = 0.0576,
wR2 = 0.1270 (two molecules in the unit cell + EtOAc). Confirmed by
1H−1H COSY and NOESY experiments as well as single crystal X-ray
1-((E)-4-(4-Fluorophenyl)-3-nitro-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3i). Yellow solid; yield 72% (171 mg); mp
116−118 °C; IR (KBr, cm−1) 3056 (m), 2987 (w), 1655 (w), 1603
(w), 1564 (w), 1527 (m), 1510 (m), 1422 (w), 1336 (m), 1266 (s),
1
1161 (m), 745 (vs); H NMR (400 MHz, CDCl3) δ 3.74 (d, J = 7.3
Hz, 2H), 5.16 (t, J = 7.3 Hz, 1H), 7.16 (t, J = 8.6 Hz, 2H), 7.50 (t, J =
7.7 Hz, 4H), 7.56 (dd, J = 8.6, 5.3 Hz, 2H), 7.67 (t, J = 7.7 Hz, 2H),
7.78 (dd, J = 7.7, 0.8 Hz, 4H), 8.13 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 24.27, 79.06, 116.73 (d, JC−F = 22.0 Hz), 127.37 (d, JC−F
=
5.0 Hz), 129.41 (d, JC−F = 2.0 Hz), 132.40 (d, JC−F = 8.0 Hz), 135.04,
136.82, 137.54, 145.01, 162.72, 165.24; MS (ES+, Ar) m/z (rel
intensity) 476 (MH+, 100); HRMS (ES+, Ar) calcd for C22H19NO6S2F
476.0638, found 476.0627.
analysis.
1-((E)-3-Nitro-4-(4-nitrophenyl)-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3j). Yellow solid; yield 61% (153 mg); mp
158−160 °C; IR (KBr, cm−1) 3066 (w), 2926 (w), 1657 (w), 1525
(s), 1448 (w), 1345 (vs), 1264 (w), 1157 (m), 1079 (w), 749 (m), 737
(m); 1H NMR (400 MHz, CDCl3) δ 3.69 (d, J = 7.5 Hz, 2H), 5.14 (t,
J = 7.5 Hz, 1H), 7.49−7.53 (m, 4H), 7.67−7.73 (m, 3H), 7.76−7.78
(m, 4H), 8.21 (s, 1H), 8.31 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz,
CDCl3) δ 24.41, 78.96, 124.45, 129.46, 129.52, 130.63, 135.22, 135.24,
137.43, 137.84, 147.77, 148.62; MS (ES+, Ar) m/z (rel intensity) 526
(MNa+, 8), 525 (29), 520 (38), 505 ([MH + 1]+, 16), 504 (MH+, 32),
503 (M+, 100), 297 (17); HRMS (ES+, Ar) calcd for
C22H19N2O8S2Na 526.0481, found 526.0459.
(E)-2-(2-Nitro-4,4-bis(phenylsulfonyl)but-1-enyl)furan (3k).
Yellow solid; yield 80% (179 mg); mp 126−128 °C; IR (KBr,
cm−1) 3152 (w), 3064 (m), 2927 (w), 1648 (s), 1560 (m), 1513 (s),
1448 (w), 1314 (vs), 1158 (vs), 1080 (m), 1024 (m), 928 (m), 753
(s); 1H NMR (400 MHz, CDCl3) δ 4.05 (d, J = 7.3 Hz, 2H), 5.18 (t, J
= 7.3 Hz, 1H), 6.58 (dd, J = 3.5, 1.8 Hz, 1H), 6.96 (d, J = 3.5 Hz, 1H),
7.50−7.55 (m, 5H), 7.67 (t, J = 7.5 Hz, 2H), 7.86−7.87 (m, 4H), 7.89
(s, 1H); 13C NMR (100 MHz, CDCl3) δ 24.70, 80.17, 113.48, 122.64,
123.79, 129.31, 129.50, 134.87, 138.01, 141.01, 146.82, 147.73; MS
(ES+, Ar) m/z (rel intensity) 449 ([MH + 1]+, 32), 448 (MH+, 100),
447 (12), 402 (44), 398 (16); HRMS (ES+, Ar) calcd for
C20H18NO7S2 (MH+) 448.0525, found 448.0533.
(E)-2-(2-Nitro-4,4-bis(phenylsulfonyl)but-1-enyl)thiophene
(3l). Yellow solid; yield 86% (200 mg); mp 134−136 °C; IR (KBr,
cm−1) 3225 (w), 3060 (w), 2944 (w), 1642 (s), 1583 (w), 1503 (m),
1495 (m), 1449 (w), 1402 (w), 1325 (s), 1303 (vs), 1154 (s), 1082
(m), 732 (s); 1H NMR (400 MHz, CDCl3) δ 3.89 (d, J = 7.3 Hz, 2H),
5.27 (t, J = 7.3 Hz, 1H), 7.19 (dd, J = 5.0, 3.7 Hz, 1H), 7.52 (td, J =
8.1, 1.0 Hz, 4H), 7.57 (d, J = 3.7 Hz, 1H), 7.66−7.70 (m, 3H), 7.86
(dd, J = 8.1, 1.0 Hz, 4H), 8.29 (s, 1H); 13C NMR (100 MHz, CDCl3)
δ 25.26, 79.10, 128.65, 129.20, 129.39, 131.26, 133.62, 133.69, 134.97,
136.62, 137.87, 141.12; MS (ES+, Ar) m/z (rel intensity) 466 ([MH +
2]+, 18), 465 ([MH + 1]+, 26), 464 (MH+, 100), 418 (22); HRMS (ES
+, Ar) calcd for C20H18NO6S3 (MH+) 464.0296, found 464.0285.
1-((1E,3E)-4-Nitro-6,6-bis(phenylsulfonyl)hexa-1,3-dienyl)-
benzene (3m). Yellow solid; yield 75% (181 mg); mp 206−208 °C;
IR (KBr, cm−1) 3055 (w), 2923 (w), 1629 (vs), 1496 (m), 1445 (w),
1-((E)-4-Cyclohexyl-3-nitro-1-(phenylsulfonyl)but-3-
enylsulfonyl)benzene (3o). White solid; yield 61% (141 mg); mp
122−124 °C; IR (KBr, cm−1) 2923 (m), 2846 (w), 1645 (vs), 1509
1
(m), 1446 (w), 1315 (vs), 1149 (s), 738 (m); H NMR (400 MHz,
CDCl3) δ 1.15−1.28 (m, 3H), 1.32−1.42 (m, 2H), 1.70−1.78 (m,
5H), 2.57 (qt, J = 10.9, 3.8 Hz, 1H), 3.50 (d, J = 7.0 Hz, 2H), 5.04 (t, J
= 7.0 Hz, 1H), 7.13 (d, J = 7.0 Hz, 1H), 7.52 (td, J = 7.9, 1.1 Hz, 4H),
7.67 (tt, J = 7.9, 1.1 Hz, 2H), 7.82 (dd, J = 7.9, 1.1 Hz, 4H); 13C NMR
(100 MHz, CDCl3) δ 23.62, 25.07, 25.67, 31.56, 38.17, 79.51, 129.33,
129.44, 134.93, 138.10, 143.62, 146.87; MS (ES+, Ar) m/z (rel
intensity) 466 ([MH + 2]+, 16), 465 ([MH + 1]+, 30), 464 (MH+,
100); HRMS (ES+, Ar) calcd for C22H26NO6S2 (MH+) 464.1202,
1
found 464.1182. Confirmed by H−1H COSY and NOESY experi-
ments.
1-((Z)-3-Nitro-1-(phenylsulfonyl)oct-3-enylsulfonyl)benzene
(3p). White solid; yield 62% (135 mg); mp 102−104 °C; IR (KBr,
cm−1) 3066 (w), 2959 (m), 2934 (m), 1657 (m), 1657 (s), 1646 (s),
1520 (s), 1448 (m), 1334 (vs), 1311 (s), 1157 (vs), 1079 (m), 737
1
(s); H NMR (400 MHz, CDCl3) 0.91 (t, J = 7.4 Hz, 3H), 1.39
(sextet, J = 7.4 Hz, 2H), 1.51 (q, J = 7.4 Hz, 2H), 2.43 (q, J = 7.4 Hz,
2H), 3.49 (d, J = 7.0 Hz, 2H), 5.03 (t, J = 7.0 Hz, 1H), 7.31 (t, J = 7.4
Hz, 1H), 7.53 (t, J = 7.6 Hz, 4H), 7.68 (t, J = 7.6 Hz, 2H), 7.81−7.83
(m, 4H); 13C NMR (100 MHz, CDCl3) δ 13.94, 22.62, 23.62, 28.59,
30.31, 79.26, 129.32, 129.44, 134.96, 138.06, 143.16, 144.87; MS (ES+,
Ar) m/z (rel intensity) 440 ([MH + 2]+, 15), 439 ([MH + 1]+, 27),
438 (MH+, 100), 420 (15), 278 (54); HRMS (ES+, Ar) calcd for
C20H24NO6S2 (MH+) 438.1045, found 438.1049.
(E)-1-Methoxy-4-(2-nitro-4-(phenylsulfonyl)but-1-enyl)-
benzene (4a). Yellow solid; yield 25% (44 mg); mp 116−118 °C; IR
(KBr, cm−1) 3060 (w), 2934 (w), 1645 (w), 1603 (s), 1519 (s), 1506
1
(s), 1446 (m), 1317 (m), 1262 (m), 1179 (s), 1143 (m); H NMR
(400 MHz, CDCl3) δ 3.28−3.31 (m, 2H), 3.43−3.47 (m, 2H), 3.87 (s,
3H), 6.95 (d, J = 8.8 Hz, 2H), 7.54 (d, J = 8.8 Hz, 2H), 7.61 (td, J =
7.6, 1.4 Hz, 2H), 7.71 (tt, J = 7.6, 1.4 Hz, 1H), 7.94−7.96 (m, 2H),
8.11 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 22.00, 53.30, 55.71,
115.17, 123.40, 128.35, 129.73, 132.57, 134.34, 136.63, 138.55, 144.65,
162.15; MS (ES+, Ar) m/z (rel intensity) 370 (MNa+, 100); HRMS
(ES+, Ar) calcd for C17H18NO5SNa 371.0803, found 371.0800.
D
dx.doi.org/10.1021/jo400528j | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
One-Pot Metal/Acid Reduction−Sulfone Elimination of RC
Adducts 3. To a stirred solution of RC adduct 3 (0.2 mmol) in a
mixture of MeOH (1.5 mL), water (0.5 mL), and conc HCl (0.2 mL)
was added iron dust (35 mg, 0.6 mmol). The resulting reaction
mixture was heated to reflux on a water bath. After completion of
reaction (monitored by TLC, ∼30 min), the mixture was cooled to
ambient temperature and filtered through a Celite pad. The filtrate was
concentrated in vacuo, and the residue was diluted with water (5 mL),
basified with 30% NaOH (10 mL), and extracted with ethyl acetate (3
× 10 mL). The combined organic layers were washed with brine (5
mL) and concentrated in vacuo, and the residue was purified by silica
gel column chromatography by eluting with 20% EtOAC-pet ether.
(2E,3E)-4-(Phenylsulfonyl)-1-p-tolylbut-3-en-2-one Oxime
(5a). White solid; yield 48% (30 mg, ∼86:14, inseparable); mp
126−128 °C; IR (KBr, cm−1) 3391 (m), 3060 (w), 2924 (m), 2854
(w), 1608 (w), 1515 (w), 1448 (m), 1309 (vs), 1150 (vs), 1085 (s),
(3) (a) Mc Clure, J. D. U.S. Patent 3225083, 1965. (b) Baizer, M. M.;
Anderson, J. D. J. Org. Chem. 1965, 30, 1357. (c) Basavaiah, D.;
Gowriswari, V. V. L.; Dharma Rao, P.; Bharathi, T. K. J. Chem. Res. (S)
1995, 267.
(4) (a) Amri, H.; Rambaud, M.; Villieras, J. Tetrahedron Lett. 1989,
30, 7381. (b) Drewes, S. E.; Emslie, N. D.; Karodia, N. Synth. Commun.
1990, 20, 1915. (c) Jenner, G. Tetrahedron Lett. 2000, 41, 3091.
(5) (a) Amri, H.; Villieras, J. Tetrahedron Lett. 1986, 27, 4307.
(b) Basavaiah, D.; Gowriswari, V. V. L.; Bharathi, T. K. Tetrahedron
Lett. 1987, 28, 4591. (c) Mc Dougal, S. E.; Schaus, S. E. Angew. Chem.,
Int. Ed. 2006, 45, 3117.
(6) Kaye, P. T.; Nocanda, X. W. J. Chem. Soc., Perkin Trans. 1 2002,
1318.
(7) Acrylate and acrylonitrile with fumaric/maleic esters: (a) Morita,
K.; Kobayashi, T. Bull. Chem. Jpn. 1969, 42, 2732. Acrylate with
acrylonitrile: (b) Mc Clure, J. D. J. Org. Chem. 1970, 35, 3045. Enones
with acrylate, acrylonitrile, and vinyl sulfone: (c) Hwu, J. R.;
Hakimelahi, G. H.; Chou, C.-T. Tetrahedron Lett. 1992, 33, 6469.
The same authors proposed Michael addition of the dienoate
generated from the β-alkyl enone by the base to the desired activated
alkene as the pathway, rather than the RC pathway. (d) Enals with
vinyl sulfone: Atienza, R. L.; Scheidt, K. A. Aust. J. Chem. 2011, 64,
1158. Acrylonitrile with α-halomethyl acrylate and vinyl ketone:
(e) Basavaiah, D.; Kumaragurubaran, N.; Sharada, D. S. Tetrahedron
Lett. 2001, 42, 85. Acrylate, acrylonitrile, and vinyl ketone with α-
bromomethyl acrylate: (f) Basavaiah, D.; Sharada, D. S.;
Kumaragurubaran, N.; Reddy, R. M. J. Org. Chem. 2002, 67, 7135.
Allenoate with enone: (g) Evans, C. A.; Miller, S. J. J. Am. Chem. Soc.
2003, 125, 12394. MVK and acrylate with dihalonaphthoquinones:
(h) Lee, C. H.; Lee, K.-J. Synthesis 2004, 12, 1941.
(8) Intramolecular, selected articles: (a) Brown, P. M.; Kappel, N.;
Murphy, P. J.; Koles, S. J.; Hursthouse, M. B. Tetrahedron 2007, 63,
1100. (b) Luis, A. L.; Krische, M. J. Synthesis 2004, 15, 2579.
(c) Thalji, R. K.; Roush, W. R. J. Am. Chem. Soc. 2005, 127, 16778.
(d) Siedel, F. O.; Gladysz, J. A. Adv. Synth. Catal. 2008, 350, 2443.
Intramolecular asymmetric: (e) Aroyan, C. E.; Miller, S. J. J. Am. Chem.
Soc. 2007, 129, 256.
1
998 (m), 831 (m), 800 (m), 754 (m); H NMR (CDCl3, 400 MHz,
major isomer) δ 2.28 (s, 3H), 3.83 (s, 2H), 6.65 (d, J = 15.6 Hz, 1H),
7.01 (ABq, J = 16.5 Hz, 4H), 7.45 (d, J = 15.6 Hz, 1H), 7.50−7.53 (m,
2H), 7.60−7.64 (m, 1H), 7.79−7.84 (m, 2H); 13C NMR (CDCl3, 100
MHz, major isomer) δ 21.16, 30.33, 127.84, 128.33, 129.53, 129.64,
132.10, 132.37, 133.80, 136.57, 139.41, 140.06, 155.60; MS (ES+) m/z
(rel intensity) 338 (MNa+, 27), 325 (100), 186 (21), 132 (10); HRMS
(ES+) calcd for C17H17NO3SNa (MNa+) 338.0821, found 338.0821.
(2E,3E)-1-(4-Fluorophenyl)-4-(phenylsulfonyl)but-3-en-2-
one Oxime (5b). White solid; yield 50% (32 mg, ∼89:11,
inseparable); mp 156−158 °C; IR (KBr, cm−1) 3509 (s), 3064 (w),
2924 (w), 1604 (m), 1583 (m), 1510 (s), 1324 (s), 1226 (m), 1151
1
(vs), 1085 (m), 826 (m), 754 (m); H NMR (CDCl3, 400 MHz,
major isomer) δ 3.83 (s, 2H), 6.64 (d, J = 15.6 Hz, 1H), 6.88−6.94
(m, 2H), 7.05−7.09 (m, 2H), 7.50−7.55 (m, 3H), 7.62−7.66 (m, 1H),
7.82−7.84 (m, 2H); 13C NMR (CDCl3, 100 MHz, major isomer) δ
29.94, 115.83 (d, JC−F = 22.0 Hz), 127.83, 129.62, 130.02 (d, JC−F
=
8.0 Hz), 130.89 (d, JC−F = 4.0 Hz), 132.38, 133.98, 139.26, 139.91,
155.24, 161.86 (d, JC−F = 244.0 Hz); MS (ES+) m/z (rel intensity)
320 (MH+, 100), 295 (24), 245 (31), 231 (33); HRMS (ES+) calcd
for C16H15FNO3S (MH+) 320.0751, found 320.0739.
(9) For selected recent examples: (a) Webber, P.; Krische, M. J. J.
Org. Chem. 2008, 73, 9379. (b) Winbush, S. M.; Mergott, D. J.; Roush,
W. R. J. Org. Chem. 2008, 73, 1818. (c) Stark, L. M.; Pekari, K.;
Sorensen, E. J. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 1064.
(10) Formaldehyde: (a) Rastogi, N.; Namboothiri, I. N. N.;
Cojocaru, M. Tetrahedron Lett. 2004, 45, 4745. (b) Mohan, R.;
Rastogi, N.; Namboothiri, I. N. N.; Mobin, S. M.; Panda, D. Bioorg.
Med. Chem. 2006, 14, 8073. Other carbonyl compounds: (c) Deb, I.;
Dadwal, M.; Mobin, S. M.; Namboothiri, I. N. N. Org. Lett. 2006, 8,
1201. (d) Deb, I.; Shanbhag, P.; Mobin, S. M.; Namboothiri, I. N. N.
Eur. J. Org. Chem. 2009, 4091. (e) Kuan, H. -H.; Reddy, R. J.; Chen, K.
Tetrahedron 2010, 66, 9875. Imines: (f) Rastogi, N.; Mohan, R.;
Panda, D.; Mobin, S. M.; Namboothiri, I. N. N. Org. Biomol. Chem.
2006, 4, 3211. (g) Rajesh, K.; Shanbhag, P.; Raghavendra, M.;
Bhardwaj, P.; Namboothiri, I. N. N. Tetrahedron Lett. 2010, 51, 846.
(11) Dadwal, M.; Mobin, S. M.; Namboothiri, I. N. N. Org. Biomol.
Chem. 2006, 4, 2525.
ASSOCIATED CONTENT
* Supporting Information
CIF file for 3n and copies of NMR spectra for all the new
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
■
S
AUTHOR INFORMATION
Corresponding Author
*E-mail: irishi@iitb.ac.in.
Notes
■
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
I.N.N.N. thanks DST India for financial assistance. R.K. and
T.K. thank CSIR India for a senior research fellowship.
■
(12) Dadwal, M.; Mohan, R.; Panda, D.; Mobin, S. M.; Namboothiri,
I. N. N. Chem. Commun. 2006, 338.
(13) Shanbhag, P.; Nareddy, P. R.; Dadwal, M.; Mobin, S. M.;
Namboothiri, I. N. N. Org. Biomol. Chem. 2010, 8, 4867.
REFERENCES
■
(1) (a) Morita, K.; Suzuki, Z.; Hirose, H. Bull. Chem. Soc. Jpn. 1968,
41, 2815. (b) Baylis, A. B.; Hillman, M. E. D. German Patent DE 445
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dx.doi.org/10.1021/jo400528j | J. Org. Chem. XXXX, XXX, XXX−XXX