Improved one-pot synthesis of styryl tetrahydrofurans and cyclohexanes by radical addition to β-nitrostyrenes in the presence of benzoyl peroxide

Article abstract of DOI:10.1002/chem.200204571

Stereoselective styryl derivatives have been prepared based on radical substitution (addition-elimination) of heterocycles or cyclohydrocarbons units to (E)-β-nitrostyrenes 1 using a common radical initiator benzoyl peroxide. High reactivity and selectivity with wide substrate scope were attained by using this easy methodology. The reactions using easily obtained and one-pot potential starting materials gave excellent trans-selectivity with medium to high yields in all cases. Synthetic utility of this approach has been demonstrated by the preparation of various trans-styryl derivatives.

Full text of DOI:10.1002/chem.200204571

FULL PAPER
Improved One-Pot Synthesis of Styryl Tetrahydrofurans and Cyclohexanes by
Radical Addition to b-Nitrostyrenes in the Presence of Benzoyl Peroxide
Yeong-Jiunn Jang, Yuh-Kuo Shih, Jing-Yuan Liu, Wen-Yu Kuo, and Ching-Fa Yao*[a]
Abstract: Stereoselective styryl derivatives have been prepared based on radical
substitution (addition elimination) of heterocycles or cyclohydrocarbons units to
(E)-b-nitrostyrenes 1 using a common radical initiator benzoyl peroxide. High
reactivity and selectivity with wide substrate scope were attained by using this easy
methodology. The reactions using easily obtained and one-pot potential starting
materials gave excellent trans-selectivity with medium to high yields in all cases.
Synthetic utility of this approach has been demonstrated by the preparation of
various trans-styryl derivatives.
Keywords: alkenes ¥ heterocycles ¥
peroxides ¥ radical reactions
anyl radical in 45 and 48% yield, respectively.[1] It also has
been reported by Fuchs and co-workers that b-heterocyclos-
tyrenes and b-cyclostyrenes can be prepared from the treat-
ment of styryl triflone with AIBN.[2] But both of these
methods are encountering the situation that the preparation
of starting substrates they used are laborious and low yield.
Introduction
In the last two decades carbon-carbon bonds formation has
been increasingly achieved by the addition of carbon centered
radicals to carbon carbon multiple bonds. It is known from
À
the literature that the addition of a-heterosubstituted radicals
to styryl sulfimides[1] and styryl triflone[2] can give styryl
heterocycles. This fact that tetrahydrofuran 2 and tetrahy-
dropyran 5 can add to alkenes under radical-reaction con-
ditions prompted us to investigate similar reactions with (E)-
b-nitrostyrenes 1, which if successful, would provide a
potential one-pot route[3] and superior methodology to
synthesize different styryl derivatives due to the easily and
cheaply acquired starting materials (b-nitrostyrenes 1).
Traditionally, styryl heterocycles are prepared by Horner
Emmons approach of the alkyl(diphenyl)phosphine oxide
with a carbonyl compound.[4] Unfortunately, this kind of
protocol is low stereoselectivity for the preparation of b-
substituted styrenes due to the generation of both erythro- and
threo-b-hydroxyalkyl(diphenyl)phosphine oxides. To avoid
the problem of separation, some research have been done
by radical-type methodology. Clarket al. have utilized
benzoyl peroxide 3 or triethylborane to mediate the addi-
tion elimination of styryl sulfimides with the tetrahydrofur-
Results and Discussion
Nitro-olefins are useful intermediates in organic synthesis and
are important structural units which can be used as starting
materials for many classes of compounds. Our previous study
found that high yields of (E)-alkenes can be generated when
(E)- or (Z)-b-nitrostyrenes 1 react with triethylborane in
tetrahydrofuran solution at room temperature in the presence
of oxygen in the air as radical initiator.[5] All these results
indicate that b-nitrostyrenes 1 are good radical acceptors and
can react with alkyl radicals from different source to generate
alkenes under different conditions and the reaction mecha-
nism is proposed to be free-radical addition elimination
reaction. In this paper, we wish to report a reformative and
effective method, based on our previous study, to synthesize
different styryl heterocycles by reaction of b-nitrostyrenes 1
À
with different alkyl radicals which were generated from C H
abstraction by benzoyl peroxide 3.
[a] Prof. Dr. C.-F. Yao, Y.-J. Jang, Y.-K. Shih, J.-Y. Liu, W.-Y. Kuo
Department of Chemistry
In an initial experiment, (E)-b-nitrostyrene (1a) was
treated with 3 equiv benzoyl peroxide 3 in tetrahydrofuran 2
and heated under reflux for 12 hours. As expected, (E)-styryl
tetrahydrofuran 4a was obtained as the sole product in 89%
yield (Table 1, entry 1), and none of the Z-isomer was
detected in the crude product. Similarly, the reaction of
benzoyl peroxide 3 with other (E)-b-nitrostyrenes having
National Taiwan Normal University
88, Sec. 4, Tingchow Road
Taipei, 116 (Taiwan)
Republic of China
E-mail: cheyaocf@scc.ntnu.edu.tw
Supporting information for this article is available on the WWW under
http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2003, 9, 2123 2128
DOI: 10.1002/chem.200204571
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2123

C.-F. Yao et al.
FULL PAPER
Table 1. Preparation of b-(2-furyl)styrenes 4 from the reaction of b-
nitrostyrenes 1, tetrahydrofuran 2, and benzoyl peroxide 3 (reaction
mixture heated under reflux).
electron-withdrawing groups 1b e (Table 1, entries 2 5)
gave the corresponding (E)-styryl tetrahydrofuran 4b e,
respectively, in good to high yields. On the other hand
reaction of (E)-b-nitrostyrenes having electron-donating
group 1 f (Table 1, entry 6) with benzoyl peroxide 3 under
identical reaction conditions led to a decrease in yield. We
attributed this result to the lower reactivity of (E)-p-methoxy-
b-nitrostyrene (1 f) due to the well electron-donating ability of
methoxy group. In the last three cases (Table 1, entries 7 9),
we extended the category of our substrates to survey this
reaction. Not surprisingly, medium to good yields were
acquired both hetero-aromatic substrates 1g,h (Table 1,
entries 7 and 8) and high steric-hindrance substrate 1i
(Table 1, entry 9). Alternatively, if UV photolysis (l ˆ
253.7 nm) was used to initiate the radical process instead of
heating, the overall yield of the reaction of b-nitrostyrene 1a
with benzoyl peroxide 3 (2.25 equiv) in tetrahydrofuran 2 for
4 h would be decreased (Table 1, 4a from 89 to 82%).
Identical phenomena were observed for other b-nitrostyrenes
when benzoyl peroxide 3 was initiated by the photochemical
strategy. However, due to our ultimate aim for developing an
one-pot route all further reactions were conducted under
reflux reaction conditions. In all these cases, no other regio- or
stereoisomers were obtained. These results (Table 1, en-
tries 1 9) indicated that this method was widely applicable
for the preparation of (E)-styryl tetrahydrofurans 4. Thus an
easy and convenient route to tetrahydrofuran derivatives has
been developed.
Ar
Ar
O
Bz2O2 (3)
+
(1)
X
O
X
NO2
1a-i
2
4a-i
f: Ar = p-MeO-Ph ; X = H
g: Ar = 2-furyl ; X = H
h: Ar = 2-thienyl ; X = H
i: Ar = Ph ; X = Ph
a: Ar = Ph ; X = H
b: Ar = p-Cl-Ph ; X = H
c: Ar = o-F-Ph ; X = H
d: Ar = p-F-Ph ; X = H
e: Ar = 2-naphthyl ; X =H
Entry
1
2
3
t
4
Yield
[%][a]
[mL]
[equiv]
[h]
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1e
1 f
1g
1h
15
15
15
15
15
15
15
15
3
3
3
3
3
3
3
3
12
12
12
12
12
15
12
12
4a
4b
4c
4d
4e
4 f
4g
4h
89
81
85
77
80
48
69
60
[a] NMR Yield.
in the reaction; the b- and g-regioisomer which we originally
did not anticipate actually exceeded half of the total yield.
À
This special kind of regioselectivity of the C H functionalized
The mechanism of this reaction is presumably similar to our
previous study in the radical addition elimination reaction of
b-nitrostyrenes 1 and different alkyl radicals.[5] The initial step
radical reaction of tetrahydropyran 5 has not been observed
before, and we presume that this might have the following
reasons: 1) the difference in the rate of abstraction of
hydrogens a to oxygen between six-membered cyclic- and
five-membered cyclic ethers; 2) the preeminent radical
trapping ability of b-nitrostyrenes 1. Owing mainly to the
huge decrease in the reaction rate of the a-hydrogen
abstraction of tetrahydropyran 5 compared with tetrahydro-
furan 2,[6] the b- and g-hydrogen abstraction became note-
worthy and important enough to compete with the a-hydro-
gen abstraction. At this stage, the excellent radical trapping
ability of our acceptor played a conclusive role to form this
regioselectivity. Once a radical formed (a-, b- or g-radicals)
after the hydrogen abstraction, it is added to the very reactive
b-nitrostyrenes 1, so that the regioselectivity of hydrogen
abstraction process determines the selectivity of the reaction.
À
could be the a-C H abstraction of tetrahydrofuran 2 with the
benzoyl or phenyl radical species generated from benzoyl
peroxide 3. The resulting tetrahydrofuran a-carbon radical
species would react with b-nitrostyrenes 1 and radical attack
must take place at the b-carbon of b-nitrostyrenes 1. Finally,
the benzylic radical generated by radical attackwould under-
go elimination to yield (E)-alkene due to the product stability
of (E)-alkene is much stable than (Z)-alkene in energy. In
addition to (E)-1a, (Z)-1a was also used to react with 2 under
similar conditions as described above (Table 1, entry 1). As
expected, 87% yield of the same product (E)-4a was also
obtained, and this result is actually consistent with our
previous report.[5]
Not only the reaction of the
five-membered cyclic ether
Table 2. Preparation of b-(2-pyranyl)styrenes 6, b-(3-pyranyl)styrenes 7 and b-(4-pyranyl)styrenes 8 from the
reaction of b-nitrostyrenes 1, tetrahydropyran 5, and benzoyl peroxide 3 (reaction mixture heated under reflux).
(tetrahydrofuran 2) proceeded
in good yields, but also that of
six-membered cyclic ether (tet-
rahydropyran 5). The reaction
of b-nitrostyrene 1a and tetra-
hydropyran 5 under analogous
conditions gave the corre-
sponding tetrahydropyran de-
rivative isomers 6a, 7a, and 8a
in 41, 28, and 21% yield, re-
spectively (Table 2, entry 1).
Herein three regioisomers a-,
b- and g-forms were observed
Ar
Ar
Ar
O
Ar
Bz2O2 (3)
X
X
X
+
+
+
(2)
O
X
NO2
O
O
1
5
6
7
8
Entry
1
5
3
t
6
7
8
[mL]
[equiv]
[h]
[yield/%][a]
[yield/%][a]
[yield/%][a]
1
2
3
4
1a
1b
1c
1d
10
10
10
10
3.25
3.5
2.75
2.75
6
6
6
9
6a [41]
6b [39]
6c [56]
6d [47]
7a [28]
7b [26]
7c [22]
7d [27]
8a [21]
8b [22]
8c [22]
8d [20]
[a] NMR Yield.
2124
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2003, 9, 2123 2128

Radical Addition to b-Nitrostyrenes
2123 2128
Table 4. Preparation of b-cyclopentylstyrenes 12 from the reaction of b-
nitrostyrenes 1, cyclopentane 11, and benzoyl peroxide 3 in toluene heated
under reflux.
On the other hand, the a-hydrogen abstraction rate factor was
so huge for tetrahydrofuran 2 that we cannot observe any b-
products in the crude GC-MS analysis.
Ar
Respecting the results above, we next examined the
reaction of cyclohexane 9. Treatment of b-nitrostyrene 1a
with 2.5 equiv benzoyl peroxide 3 in the presence of cyclo-
hexane 9 gave the corresponding styryl derivative 10a in 90%
yield (Table 3, entry 1). The tendency of the reactivities of b-
nitrostyrenes 1 in the reaction with cyclohexane 9 was the
same as that with tetrahydrofuran 2, although all cases were
more efficient than those for the tetrahydrofuran 2 series
(Table 1). After the survey of the reaction conditions for
tetrahydrofuran 2, tetrahydropyran 5, and cyclohexane 9, the
reaction rates for b-nitrostyrenes 1 with cyclohexane 9 were
much faster than those of the other two, and required the least
amount of the reaction time and benzoyl peroxide 3.
Ar
Bz2O2 (3)
X
+
(4)
toluene
X
NO2
1
11
12
Entry
1
11
[mL]
Toluene
[mL]
3
t
12
Yield
[%][a]
[equiv]
[h]
1
2
3
4
5
1a
1b
1f
1g
1h
3
3
3
3
3
12
12
12
12
12
3.25
3
2.5
2.75
2.75
12
12
6
10
9
12a
12b
12f
12g
12h
100
100
73
64
68
[a] NMR Yield.
respectively resulting from a conformable protocol (Table 4,
entries 2 5). Then, compounds 14a and 16a, with a medium
sized hydrocarbon ring, were obtained both in 100% yield
from cycloheptane 13 and cyclooctane 15, respectively
[Eqs. (5) (6)]. Although there is a much larger steric
hindrance in medium-sized cycloalkane, the reactivity and
yield were hardly reduced.
Table 3. Preparation of b-cyclohexylstyrenes 10 from the reaction of b-
nitrostyrenes 1, cyclohexane 9, and benzoyl peroxide 3 (reaction mixture
heated under reflux).
Ar
Ar
Bz2O2 (3)
X
+
(3)
X
NO2
1
9
10
Ph
Bz2O2 (3)
(2.5 equiv)
Ph
H
Entry
1
9
3
t
10
Yield
[%][a]
H
+
(5)
[mL]
[equiv]
[h]
benzene (8 mL)
reflux 6h
NO2
1
2
3
4
5
6
7
8
9
1a
10
10
10
10
10
10
10
10
10
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
4
4
4
4
4
3
4
3
6
10a
10b
10c
10d
10e
10f
10g
10h
10i
90
95
100
100
74
75
32
82
82
1a
13 (2 mL)
14a (100%yield)
1b
1c
1d
1e
1f
1g
1h
1i
Ph
H
Bz2O2 (3)
Ph
(2.75 equiv)
+
(6)
H
NO2
benzene (8 mL)
reflux 12h
1a
15 (2 mL)
16a (100% yield)
[a] NMR Yield.
The above results prompted us to investigate the synthesis
of styryl-(1,3)-dioxolane based on the present methodology.
Treatment of b-nitrostyrene 1a with benzoyl peroxide 3 in the
presence of 1,3-dioxolane 17 gave the corresponding adduct
18a in 56% yield (Table 5, entry 1). In this reaction we
Now we were interested in the reaction of b-nitrostyrenes 1
and five-, seven-, and eight-membered cyclic hydrocarbons,
because of the apparent difference in reactivities between
tetrahydrofuran 2, tetrahydropyran 5 and cyclohexane 9. First,
the reaction of a cyclopentane 11 and toluene co-solvent
solution of b-nitrostyrene 1a with benzoyl peroxide 3 heated
under reflux furnished the desired (E)-styryl cyclopentane
product 12a quantitatively as expected (Table 4, entry 1). The
strategy of using toluene as co-solvent instead of radical
precursor itself as the only solvent as described above was in
order to elevate the temperature inside the reaction system
under refluxing as a result of the low boiling point of
cyclopentane 11. Benzene was one of our first choices to
increase the reaction temperature so that to initiate the
cleavage of benzoyl peroxide 3; however, some starting
material (b-nitrostyrene 1a) was always recovered under such
reaction conditions. Finally, a solution with the specified ratio
of toluene and cyclopentane 11 satisfied our requests and was
adopted for further investigations. Applied to other b-nitro-
styrenes 1b, 1 f, 1g, and 1h, these conditions led in fact to the
formation of cyclopentane derivatives 12b, 12 f, 12g, and 12h,
Table 5. Preparation of b-(1,3-dioxolan)styrene 18 from the reaction of b-
nitrostyrenes 1, 1,3-dioxolane 17, and benzoyl peroxide 3 (reaction mixture
heated under reflux).
Ar
Ar
Bz2O2 (3)
O
O
+
X
O
(7)
X
NO2
O
1
17
18
Entry
1
17
[mL]
3
t
18
Yield
[%][a]
[equiv]
[h]
1
2
3
4
5
1a
1b
1 f
1g
1h
10
10
10
10
10
2.75
2.75
3
2.5
2.5
6
5
6
9
6
18a
18b
18 f
18g
18h
56
60
57
16[b]
46
[a] NMR Yield. [b] The compound 18g was unstable under such reaction
conditions.
Chem. Eur. J. 2003, 9, 2123 2128
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¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2125

C.-F. Yao et al.
FULL PAPER
combined formylation and aldehyde protection in one single
step and performed a key step for synthesis of conjugated
aldehyde.
Experimental Section
All reactions were performed under nitrogen in oven-dried glassware.
Radical precursors such as tetrahydrofuran, tetrahydropyran, cyclopen-
tane, cyclohexane, cycloheptane, cyclooctane and 1,3-dioxolane were
freshly distilled before use. Analytical thin-layer chromatography was
performed with E. Mercksilica gel 60F glass plates and flash chromatog-
raphy with E. Mercksilica gel 60 (230 400 mesh). MS or HRMS were
measured by JEOL JMS-D300 or JEOL JMS-HX110 spectrometer. 1H and
13C NMR spectra were recorded with a Varian Gemini-200. All NMR data
were obtained in CDCl3 solution and chemical shifts (d) were given in ppm
relative to TMS.
The development of substrates for use in radical chemistry
À
that can form carbon carbon bonds while at the same time
introducing additional functionality are of great importance.
Advantages of the radical acceptors in our current work
include their greater variety and convenience, and now we
wish to report the first examples of one-pot synthesis of styryl
tetrahydrofurans 4 and cyclohexanes 10 by the radical
reaction by combining our previous study and literature
methodology.[3]
General procedure for the reaction of radical precursors with b-nitro-
styrene
The radical precursors chosen for this study were tetrahy-
drofuran 2 and cyclohexane 9 because of their good behavior
in radical reactions to b-nitrostyrenes 1. The strategy was to
react b-nitrostyrene 1a (prepared in situ from aromatic
aldehyde 19 with nitromethane in acetic acid with a catalytic
amount of ammonium acetate at 1108C for 18 h) with benzoyl
peroxide 3 and tetrahydrofuran 2 or cyclohexane 9 as radical
precursor at the radical reaction conditions described above.
When the reaction was carried out in tetrahydrofuran 2, 46%
of (E)-styryl tetrahydrofuran 4a was observed (Scheme 1).
Similarly, when cyclohexane 9 was used, 59% of 10a was also
observed. A simple one-pot procedure has been developed in
which styryl tetrahydrofurans 4 and cyclohexanes 10 were
synthesized from cheap and easily accessible materials in
medium yields.
Preparation of (E)-4a: b-Nitrostyrene 1a (149.2 mg, 1.0 mmol) and
benzoyl peroxide 3 (726.7 mg, 3.0 mmol) were added to THF (15 mL).
The mixture was heated for 12 h under reflux and then concentrated in
vacuo. After the solvent (radical precursor) was evaporated, the residue
was purified by column chromatography on silica gel and yielded the
desired product (E)-4a as a colourless oil.
Compound (4a): 1H NMR (200 MHz, CDCl3): d ˆ 1.61 1.78 (m, 1H),
1.87 2.19 (m, 3H), 3.77 4.02 (m, 2H), 4.41 4.51 (m, 1H), 6.20 (dd, J ˆ 16,
6.6 Hz, 1H), 6.58 (d, J ˆ 16 Hz, 1H), 7.17 7.40 (m, 5H); 13C NMR
(50 MHz, CDCl3): d ˆ 25.84, 32.32, 68.12, 79.64, 126.49, 127.51, 128.54,
130.47, 130.57, 136.92.
Compound (4b): 1H NMR (200 MHz, CDCl3): d ˆ 1.62 1.79 (m, 1H),
1.81 2.21 (m, 3H), 3.79 4.03 (m, 2H), 4.41 4.52 (m, 1H), 6.18 (dd, J ˆ
15.8, 6.4 Hz, 1H), 6.54 (d, J ˆ 15.8 Hz, 1H), 7.24 7.40 (m, 4H); 13C NMR
(50 MHz, CDCl3): d ˆ 25.79, 32.26, 68.16, 79.41, 127.68, 128.68, 129.15,
‡
131.33, 133.11, 135.46; MS: m/z (%): 208 (26) [M] , 206 (72), 171 (90), 165
‡
(100); HRMS: calcd for C12H13OCl: 208.0655; found: 208.0634 [M] .
1
Compound (4c): H NMR (200 MHz,
CDCl3): d ˆ 1.64 1.80 (m, 1H), 1.89
Ph
H
Bz2O2 (3.0 equiv)
THF, reflux 12h
2.22 (m, 3H), 3.79 4.03 (m, 2H),
4.44 4.54 (m, 1H), 6.29 (dd, J ˆ 16.2,
6.6 Hz, 1H), 6.74 (d, J ˆ 16.2 Hz, 1H),
6.97 7.25 (m, 3H), 7.41 7.49 (m, 1H);
13C NMR (50 MHz, CDCl3): d ˆ 25.81,
32.27, 68.17, 79.72, 115.46, 115.90,
122.82, 122.90, 124.00, 124.08, 124.57,
124.81, 127.54, 127.61, 128.66, 128.83,
133.21, 133.32, 157.88, 162.84; MS: m/z
O
HOAc/NH4OAc
110 °C, 18h
Ph
H
4a (46% yield)
CH3NO2
O
+
NO2
H
Ph
H
Bz2O2 (2.5 equiv)
19
1a
cyclohexane
reflux 4h
‡
(%): 192 (100) [M] , 149 (65), 133
10a (59% yield)
(35), 122 (80).
Scheme 1.
1
Compound (4d): H NMR (200 MHz,
CDCl3): d ˆ 1.62 1.78 (m, 1H), 1.89
2.21 (m, 3H), 3.78 4.02 (m, 2H),
Finally we turned our attention to the radical addition
reaction mediated by benzoyl peroxide 3. Thus, when using
the radical initiation system benzoyl peroxide 3 (2.5 equiv) in
tetrahydrofuran 2 heated under reflux, the tetrahydrofuran a-
carbon radical species reacted with the acceptor 20 by a 1,4-
addition process to adduct 21 over 6 h in 70% yield.
4.40 4.51 (m, 1H), 6.12 (dd, J ˆ 15.8, 6.6 Hz, 1H), 6.55 (d, J ˆ 15.8 Hz,
1H), 6.93 7.05 (m, 2H), 7.29 7.39 (m, 2H); 13C NMR (50 MHz, CDCl3):
d ˆ 25.84, 32.32, 68.16, 79.56, 115.20, 115.64, 127.92, 128.07, 128.40, 129.34,
‡
130.35, 130.39, 133.08, 133.14, 159.92, 164.82; MS: m/z (%): 192 (100) [M] ,
149 (74), 122 (75), 109 (38).
Compound (4e): 1H NMR (200 MHz, CDCl3): d ˆ 1.68 1.93 (m, 1H),
1.94 2.28 (m, 3H), 3.82 4.08 (m, 2H), 4.55 4.65 (m, 1H), 6.23 (dd, J ˆ
15.8, 6.4 Hz, 1H), 7.30 7.61 (m, 3H), 7.74 7.85 (m, 2H), 8.10 8.16 (m,
1H); 13C NMR (50 MHz, CDCl3): d ˆ 25.82, 32.39, 68.19, 79.76, 123.91,
125.60, 125.73, 125.96, 127.57, 127.84, 128.49, 131.24, 133.65, 133.90, 134.72;
CO2Me
CO2Me
Bz2O2 (3)
CO2Me
CO2Me
‡
O
(2.5 equiv)
MS: m/z (%): 224 (72) [M] , 181 (55), 165 (100), 153 (100); HRMS: calcd
+
(8)
‡
for C16H16O: 224.1201; found: 224.1202 [M] .
reflux 6h
O
Compound (4 f): 1H NMR (200 MHz, CDCl3): d ˆ 1.62 1.78 (m, 1H),
1.86 2.19 (m, 3H), 3.80 (s, 3H), 3.82 4.03 (m, 2H), 4.40 4.50 (m, 1H),
6.07 (dd, J ˆ 15.8, 6.8 Hz, 1H), 6.53 (d, J ˆ 15.8 Hz, 1H), 6.80 6.89 (m,
2H), 7.28 7.35 (m, 2H); 13C NMR (50 MHz, CDCl3): d ˆ 25.86, 32.35,
55.21, 68.03, 79.90, 113.94, 127.68, 128.25, 130.22, 133.59, 159.23; MS: m/z
20
2
21 (70% yield)
In conclusion, we have succeeded in the stereoselective
substitution of b-nitrostyrenes 1 leading to (E)-alkenes
exclusively. Further studies on the application of this method-
ology to synthesize other compounds is under investigation.
‡
(%): 204 (79) [M] , 161 (94), 147 (100), 134 (89).
Compound (4g): 1H NMR (200 MHz, CDCl3): d ˆ 1.62 1.78 (m, 1H),
1.81 2.19 (m, 3H), 3.77 4.01 (m, 2H), 4.41 4.51 (m, 1H), 6.09 6.46 (m,
4H), 7.33 7.40 (m, 1H); 13C NMR (50 MHz, CDCl3): d ˆ 25.75, 32.32,
2126
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2003, 9, 2123 2128

Radical Addition to b-Nitrostyrenes
2123 2128
68.16, 79.11, 107.77, 111.24, 118.59, 129.42, 141.91, 152.69; MS: m/z (%): 164
(100) [M] , 107 (36), 94 (93), 42 (63).
6.6 Hz, 1H), 6.39 (d, J ˆ 16 Hz, 1H), 7.17 7.38 (m, 5H); 13C NMR
(50 MHz, CDCl3): d ˆ 32.55, 38.30, 67.70, 126.05, 127.13, 128.30, 128.56,
‡
‡
Compound (4h): 1H NMR (200 MHz, CDCl3): d ˆ 1.62 1.78 (m, 1H),
1.85 2.19 (m, 3H), 3.77 4.01 (m, 2H), 4.39 4.49 (m, 1H), 6.05 (dd, J ˆ
15.6, 6.6 Hz, 1H), 6.71 (d, J ˆ 15.6 Hz, 1H), 6.92 7.01 (m, 2H), 7.12 7.15
(m, 1H); 13C NMR (50 MHz, CDCl3): d ˆ 25.79, 32.27, 68.16, 79.26, 123.56,
134.64, 137.57; MS: m/z (%): 188 (100) [M] , 143 (37), 91 (52); HRMS:
‡
calcd for C13H16O: 188.1201; found: 188.1198 [M] .
Compound (8b): 1H NMR (200 MHz, CDCl3): d ˆ 1.45 1.74 (m, 4H),
2.29 2.45 (m, 1H), 3.40 3.61 (m, 2H), 3.98 4.04 (m, 2H), 6.13 (dd, J ˆ
15.8, 6.6 Hz, 1H), 6.34 (dd, J ˆ 15.8, 1 Hz, 1H), 7.16 7.39 (m, 4H);
13C NMR (50 MHz, CDCl3): d ˆ 32.46, 38.28, 67.65, 127.17, 127.28, 128.68,
‡
124.17, 125.66, 127.33, 130.32, 142.12; MS: m/z (%): 180 (100) [M] , 137
(53), 123 (37), 110 (88); HRMS: calcd for C10H12OS: 180.0609; found:
‡
‡
180.0610 [M] .
128.84, 135.34, 136.10; MS: m/z (%): 222 (34) [M] , 139 (51), 125 (51), 83
‡
Compound (4i): 1H NMR (200 MHz, CDCl3): d ˆ 1.63 2.09 (m, 4H),
3.67 3.78 (m, 1H), 3.88 3.99 (m, 1H), 4.24 4.35 (m, 1H), 6.06 (d, J ˆ
9 Hz, 1H), 7.17 7.41 (m, 10H); 13C NMR (50 MHz, CDCl3): d ˆ 26.33,
32.99, 68.03, 76.62, 127.36, 127.45, 127.63, 128.12, 129.78, 129.98, 139.49,
(100); HRMS: calcd for C13H15OCl: 222.0812; found: 222.0814 [M] .
Compound (8c): 1H NMR (200 MHz, CDCl3): d ˆ 1.47 1.75 (m, 4H),
2.32 2.51 (m, 1H), 3.40 3.53 (m, 2H), 3.97 4.06 (m, 2H), 6.23 (dd, J ˆ 16,
6.8 Hz, 1H), 6.55 (d, J ˆ 16 Hz, 1H), 6.96 7.25 (m, 3H), 7.40 7.50 (m, 1H);
13C NMR (50 MHz, CDCl3): d ˆ 32.44, 38.69, 67.65, 115.45, 115.89, 120.71,
120.79, 124.02, 124.08, 125.17, 125.41, 126.98, 127.05, 128.24, 128.40, 137.13,
137.20, 157.66, 162.60.
Compound (8d): 1H NMR (200 MHz, CDCl3): d ˆ 1.39 1.73 (m, 4H),
2.28 2.46 (m, 1H), 3.34 3.53 (m, 2H), 3.97 4.05 (m, 2H), 6.07 (dd, J ˆ 16,
6.6 Hz, 1H), 6.35 (d, J ˆ 16 Hz, 1H), 6.93 7.18 (m, 2H), 7.21 7.36 (m, 2H);
13C NMR (50 MHz, CDCl3): d ˆ 32.55, 38.25, 67.67, 115.17, 115.61, 127.16,
127.42, 127.58, 133.70, 133.76, 134.38, 134.41, 159.67, 164.57.
‡
142.04, 143.74; MS: m/z (%): 250 (100) [M] , 178 (67), 173 (100), 165 (74);
‡
HRMS: calcd for C18H18O: 250.1357; found: 250.1355 [M] .
Synthesis of styryl-tetrahydropyran [(E)-6, 7, 8]: The procedure given
above was used with the precursor of radical 5 (10 mL), and the starting
materials 1a d (1 mmol) under the specified conditions shown in Table 2.
Compound (6a): 1H NMR (200 MHz, CDCl3): d ˆ 1.39 1.92 (m, 6H),
3.47 3.60 (m, 1H), 3.93 4.11 (m, 2H), 6.21 (dd, J ˆ 15.9, 5.8 Hz, 1H), 6.59
(dd, J ˆ 15.9, 1 Hz, 1H), 7.16 7.40 (m, 5H); 13C NMR (50 MHz, CDCl3):
d ˆ 23.32, 25.76, 32.14, 68.35, 77.99, 126.42, 127.43, 128.49, 129.75, 130.86,
Synthesis of styryl-cyclohexane [(E)-10]: The procedure given above was
used with the precursor of radical 9 (10 mL), and the starting materials 1a
i (1 mmol) under the specified conditions shown in Table 3.
‡
137.05; MS: m/z (%): 188 (83) [M] , 131 (75), 104 (100); HRMS: calcd for
‡
C13H16O: 188.1201; found: 188.1194 [M] .
Compound (6b): 1H NMR (200 MHz, CDCl3): d ˆ 1.41 1.93 (m, 6H),
3.48 3.60 (m, 1H), 3.93 4.11 (m, 2H), 6.18 (dd, J ˆ 16, 5.6 Hz, 1H), 6.54
(dd, J ˆ 16, 1.2 Hz, 1H), 7.23 7.33 (m, 4H); 13C NMR (50 MHz, CDCl3):
d ˆ 23.34, 25.76, 32.11, 68.43, 77.82, 127.66, 128.54, 128.71, 131.57, 133.09,
Compound (10c): 1H NMR (200 MHz, CDCl3): d ˆ 1.08 1.44 (m, 5H),
1.66 2.08 (m, 5H), 2.10 2.28 (m, 1H), 6.23 (dd, J ˆ 16.2, 6.8 Hz, 1H), 6.51
(d, J ˆ 16.2 Hz, 1H), 6.94 7.20 (m, 3H), 7.39 7.47 (m, 1H); 13C NMR
(50 MHz, CDCl3): d ˆ 25.95, 26.10, 32.80, 41.48, 115.37, 115.81, 119.62,
119.71, 123.93, 124.0, 125.72, 125.96, 126.90, 126.98, 127.83, 127.99, 139.39,
‡
135.61; MS: m/z (%): 222 (100) [M] , 187 (97), 138 (91), 131 (87); HRMS:
‡
‡
calcd for C13H15OCl: 222.0812; found: 222.0820 [M] .
139.46, 157.64, 162.57; MS: m/z (%): 204 (32) [M] , 122 (100), 109 (23);
‡
Compound (6c): 1H NMR (200 MHz, CDCl3): d ˆ 1.39 1.97 (m, 6H),
3.47 3.60 (m, 1H), 3.95 4.11 (m, 2H), 6.29 (dd, J ˆ 16.2, 5.6 Hz, 1H), 6.74
(d, J ˆ 16.2 Hz, 1H), 6.95 7.26 (m, 3H), 7.40 7.49 (m, 1H); 13C NMR
(50 MHz, CDCl3): d ˆ 23.29, 25.73, 32.05, 68.35, 78.08, 115.42, 115.86,
122.21, 122.27, 123.99, 124.05, 124.66, 124.90, 127.39, 127.46, 128.60, 128.77,
133.41, 133.50, 157.87, 162.83.
Compound (6d): 1H NMR (200 MHz, CDCl3): d ˆ 1.38 1.93 (m, 6H),
3.47 3.60 (m, 1H), 3.92 4.10 (m, 2H), 6.12 (dd, J ˆ 16.2, 5.6 Hz, 1H), 6.55
(d, J ˆ 16.2 Hz, 1H), 6.92 7.04 (m, 2H), 7.28 7.38 (m, 2H); 13C NMR
(50 MHz, CDCl3): d ˆ 23.32, 25.75, 32.14, 68.38, 77.88, 115.16, 115.60,
127.83, 127.99, 128.65, 130.62, 130.65, 133.18, 133.24, 159.86, 164.76.
HRMS; calcd for C14H17F: 204.1269; found: 204.1291 [M] .
Compound (10d): 1H NMR (200 MHz, CDCl3): d ˆ 1.06 1.43 (m, 5H),
1.60 1.90 (m, 5H), 2.07 2.19 (m, 1H), 6.07 (dd, J ˆ 16, 6.8 Hz, 1H), 6.30
(d, J ˆ 16 Hz, 1H), 6.90 7.05 (m, 2H), 7.24 7.32 (m, 2H); 13C NMR
(50 MHz, CDCl3): d ˆ 25.96, 26.10, 32.90, 41.04, 115.07, 115.49, 126.16,
127.28, 127.45, 134.24, 134.31, 136.61, 136.66, 159.51, 164.39; MS: m/z (%):
‡
204 (31) [M] , 122 (100), 109 (26); HRMS: calcd for C14H17F: 204.1314;
‡
found: 204.1311 [M] .
Compound (10e): 1H NMR (200 MHz, CDCl3): d ˆ 1.12 1.45 (m, 5H),
1.68 1.92 (m, 5H), 2.12 2.35 (m, 1H), 6.18 (dd, J ˆ 15.8, 7.0 Hz, 1H), 7.07
(d, J ˆ 15.8 Hz, 1H), 7.36 7.56 (m, 4H), 7.69 7.73 (m, 1H), 7.79 7.84 (m,
1H), 8.09 8.14 (m, 1H); 13C NMR (50 MHz, CDCl3): d ˆ 26.01, 26.16,
32.99, 41.47, 123.47, 124.0, 124.44, 125.61, 125.69, 125.73, 127.17, 128.49,
Compound (7a): 1H NMR (200 MHz, CDCl3): d ˆ 1.36 1.82 (m, 3H),
1.93 2.01 (m, 1H), 2.38 2.56 (m, 1H), 3.20 3.46 (m, 2H), 3.89 3.96 (m,
2H), 6.05 (dd, J ˆ 16, 7.2 Hz, 1H), 6.43 (d, J ˆ 16 Hz, 1H), 7.17 7.38 (m,
5H); 13C NMR (50 MHz, CDCl3): d ˆ 25.37, 29.71, 39.87, 68.12, 72.52,
‡
131.29, 133.70, 135.97, 140.24; MS: m/z (%): 236 (88) [M] , 179 (58), 165
‡
(64), 154 (100); HRMS: calcd for C18H20: 236.1565; found: 236.1567 [M] .
‡
126.08, 127.27, 128.57, 130.24, 130.86, 137.43; MS: m/z (%): 188 (32) [M] ,
Compound (10i): 1H NMR (200 MHz, CDCl3): d ˆ 1.05 1.34 (m, 5H),
1.52 1.78 (m, 5H), 2.02 2.24 (m, 1H), 5.90 (d, J ˆ 9.8 Hz, 1H), 7.12 7.42
(m, 10H); 13C NMR (50 MHz, CDCl3): d ˆ 25.52, 25.92, 33.27, 38.24, 126.73,
129 (72), 104 (100); HRMS: calcd for C13H16O: 188.1201; found: 188.1204
‡
[M] .
Compound (7b): 1H NMR (200 MHz, CDCl3): d ˆ 1.36 1.82 (m, 3H),
1.92 2.00 (m, 1H), 2.37 2.55 (m, 1H), 3.20 3.47 (m, 2H), 3.88 3.94 (m,
2H), 6.03 (dd, J ˆ 16, 7.4 Hz, 1H), 6.38 (d, J ˆ 16 Hz, 1H), 7.13 7.47 (m,
4H); 13C NMR (50 MHz, CDCl3): d ˆ 25.29, 29.62, 39.83, 68.12, 72.39,
126.80, 127.24, 128.05, 128.16, 129.81, 135.97, 139.72, 140.66, 143.0; MS: m/z
‡
(%): 262 (78) [M] , 205 (50), 180 (100), 165 (53); HRMS: calcd for C20H22
:
‡
262.1722; found: 262.1725 [M] .
Synthesis of styryl-cyclopentane [(E)-12]: The procedure given above was
used with toluene and the precursor of radical 11 (3 mL, volume ratio of 11/
toluene 1:4) as co-solvent, and the starting materials 1a,b, f h (1 mmol)
under the specified conditions shown in Table 4.
‡
127.31, 128.71, 129.09, 131.61, 132.83, 135.96; MS: m/z (%): 222 (30) [M] ,
138 (100), 129 (78); HRMS: calcd for C13H15OCl: 222.0811; found: 222.0805
‡
[M] .
Compound (7c): 1H NMR (200 MHz, CDCl3): d ˆ 1.38 1.82 (m, 3H),
1.92 2.04 (m, 1H), 2.41 2.58 (m, 1H), 3.21 3.50 (m, 2H), 3.89 3.98 (m,
2H), 6.13 (dd, J ˆ 16, 7.2 Hz, 1H), 6.59 (d, J ˆ 16 Hz, 1H), 6.96 7.23 (m,
3H), 7.37 7.46 (m, 1H); 13C NMR (50 MHz, CDCl3): d ˆ 25.31, 29.57,
40.24, 68.11, 72.39, 115.46, 115.90, 122.62, 122.70, 124.02, 124.08, 125.04,
125.28, 127.02, 127.10, 128.37, 128.54, 133.44, 133.53, 157.64, 162.59.
Compound (12a): 1H NMR (200 MHz, CDCl3): d ˆ 1.30 1.93 (m, 8H),
2.50 2.69 (m, 1H), 6.20 (dd, J ˆ 16, 7.6 Hz, 1H), 6.37 (d, J ˆ 16 Hz, 1H),
7.13 7.37 (m, 5H); 13C NMR (50 MHz, CDCl3): d ˆ 25.16, 33.15, 43.77,
‡
125.96, 126.75, 127.89, 128.49, 135.76, 137.99; MS: m/z (%): 172 (32) [M] ,
104 (89), 84 (75), 66 (100); HRMS: calcd for C13H16: 172.1252; found:
‡
172.1244 [M] .
Compound (7d): 1H NMR (200 MHz, CDCl3): d ˆ 1.35 1.90 (m, 3H),
1.92 2.01 (m, 1H), 2.37 2.54 (m, 1H), 3.19 3.46 (m, 2H), 3.87 3.95 (m,
2H), 5.96 (dd, J ˆ 16, 7.6 Hz, 1H), 6.39 (d, J ˆ 16 Hz, 1H), 6.92 7.04 (m,
2H), 7.19 7.35 (m, 2H); 13C NMR (50 MHz, CDCl3): d ˆ 25.32, 29.68,
39.80, 68.11, 72.48, 115.19, 115.61, 127.45, 127.61, 129.09, 130.59, 130.63,
133.56, 133.62, 159.73, 164.63.
Compound (12b): 1H NMR (200 MHz, CDCl3): d ˆ 1.29 1.92 (m, 8H),
2.48 2.67 (m, 1H), 6.16 (dd, J ˆ 16, 7.4 Hz, 1H), 6.31 (d, J ˆ 16 Hz, 1H),
7.07 7.43 (m, 4H); 13C NMR (50 MHz, CDCl3): d ˆ 25.22, 33.15, 43.77,
‡
126.70, 127.10, 128.53, 132.18, 136.40, 136.43; MS: m/z (%): 206 (44) [M] ,
171 (45), 138 (100), 129 (79); HRMS: calcd for C13H15Cl: 206.0862; found:
‡
206.0854 [M] .
Compound (8a): 1H NMR (200 MHz, CDCl3): d ˆ 1.46 1.74 (m, 4H),
Compound (12 f): 1H NMR (200 MHz, CDCl3): d ˆ 1.28 1.91 (m, 8H),
2.29 2.48 (m, 1H), 3.40 3.53 (m, 2H), 3.98 4.05 (m, 2H), 6.16 (dd, J ˆ 16,
2.46 2.66 (m, 1H), 3.78 (s, 3H), 6.05 (dd, J ˆ 15.8, 7.6 Hz, 1H), 6.31 (d, J ˆ
Chem. Eur. J. 2003, 9, 2123 2128
www.chemeurj.org
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2127

C.-F. Yao et al.
FULL PAPER
(100), 119 (35); HRMS: calcd for C12H14O3: 206.0943; found: 206.0954
[M] .
15.8 Hz, 1H), 6.79 6.86 (m, 2H), 7.24 7.31 (m, 2H); 13C NMR (50 MHz,
‡
CDCl3): d ˆ 25.13, 33.21, 43.74, 55.20, 113.90, 126.99, 127.22, 130.80, 133.61,
‡
Compound (18g): 1H NMR (200 MHz, CDCl3): d ˆ 3.90 3.98 (m, 2H),
4.01 4.08 (m, 2H), 5.42 (d, J ˆ 5.6 Hz, 1H), 6.10 (dd, J ˆ 15.8, 5.6 Hz, 1H),
6.34 6.39 (m, 2H), 6.58 (d, J ˆ 16.4 Hz, 1H), 7.25 7.37 (m, 1H); 13C NMR
(50 MHz, CDCl3): d ˆ 64.97, 103.40, 109.68, 111.38, 122.44, 123.56, 142.73,
158.64; MS: m/z (%): 202 (84) [M] , 159 (52), 134 (87), 121 (100); HRMS:
‡
calcd for C14H18O: 202.1358; found: 202.1361 [M] .
Compound (12g): 1H NMR (200 MHz, CDCl3): d ˆ 1.20 2.10 (m, 8H),
2.42 2.64 (m, 1H), 6. 07 6.39 (m, 4H), 7.19 7.41 (m, 1H); 13C NMR
(50 MHz, CDCl3): d ˆ 25.11, 33.08, 43.52, 105.92, 111.11, 116.74, 134.76,
‡
151.74; MS: m/z (%): 166 (5) [M] , 85 (71), 71 (84), 57 (100); HRMS: calcd
‡
for C9H10O3: 166.0630; found: 166.0608 [M] .
‡
141.19, 153.48; MS: m/z (%): 162 (12) [M] , 85 (67), 71 (85), 57 (100);
‡
Compound (18h): 1H NMR (200 MHz, CDCl3): d ˆ 3.88 3.98 (m, 2H),
4.00 4.10 (m, 2H), 5.40 (d, J ˆ 6.0 Hz, 1H), 5.99 (dd, J ˆ 15.8, 6.0 Hz, 1H),
6.85 7.04 (m, 3H), 7.19 7.22 (m, 1H); 13C NMR (50 MHz, CDCl3): d ˆ
65.00, 103.52, 124.52, 125.46, 127.14, 127.43, 127.66, 140.91; MS: m/z (%):
HRMS: calcd for C11H14O: 162.1044; found: 162.1049 [M] .
Compound (12h): 1H NMR (200 MHz, CDCl3): d ˆ 1.28 2.00 (m, 8H),
2.45 2.65 (m, 1H), 6.05 (dd, J ˆ 15.8, 7.8 Hz, 1H), 6.49 (d, J ˆ 15.8 Hz,
1H), 6.84 6.98 (m, 2H), 7.00 7.23 (m, 1H); 13C NMR (50 MHz, CDCl3):
d ˆ 25.11, 33.03, 43.56, 121.24, 122.99, 124.14, 127.21, 135.70, 143.30; MS:
‡
182 (47) [M] , 123 (25), 110 (100); HRMS: calcd for C9H10O2S: 182.0402;
‡
found: 182.0402 [M] .
‡
m/z (%): 178 (28) [M] , 110 (70), 84 (75), 66 (100); HRMS: calcd for
‡
One-pot synthesis of 4a or 10a: Benzaldehyde 19 (1 mmol) reacted with
nitromethane 2 (1 mL) in acetic acid (1 mL) with ammonium acetate
(0.1 mmol) at 1108C for 18 h to generate (E)-b-nitrostyrene 1a. After the
reaction cooled down, benzoyl peroxide and radical precursor 2 or 9 were
added to the reaction system then this mixture was hetaed under reflux to
yield the desired products (E)-4a or 10a shown in Scheme 1 according to
the procedure mentioned above.
C11H14S: 178.0817; found 178.0814 [M] .
Synthesis of styryl-cycloheptane and -cyclooctane [(E)-14a, (E)-16a]: The
procedure given above was used with benzene and the precursor of radical
13 or 15 (2 mL, volume ratio of 13 or 15/benzene 1:4) as co-solvent, and the
starting material 1a (1 mmol) under the specified conditions shown in
Equations (5) (6).
Compound (14a): 1H NMR (200 MHz, CDCl3): d ˆ 1.33 1.88 (m, 12H),
2.21 2.37 (m, 1H), 6.19 (dd, J ˆ 15.8, 6.6 Hz, 1H), 6.32 (d, J ˆ 15.8 Hz,
1H), 7.12 7.40 (m, 5H); 13C NMR (50 MHz, CDCl3): d ˆ 26.19, 28.33,
34.66, 43.17, 125.96, 126.67, 126.72, 128.46, 137.66, 138.16; MS: m/z (%): 200
Synthesis of compound 21: The procedure given above was used with the
precursor of radical 2 (15 mL), and the starting material 20 (1 mmol) under
the specified conditions shown in Equation (8).
‡
Compound (21): 1H NMR (200 MHz, CDCl3): d ˆ 1.04 (s, 3H), 1.13 (s, 3H),
1.61 1.78 (m, 1H), 1.81 1.98 (m, 3H), 3.63 3.93 (m, 10H); 13C NMR
(50 MHz, CDCl3): d ˆ 19.87, 20.51, 25.93, 26.03, 39.97, 51.80, 57.37, 68.29,
(1) [M] , 96 (100), 91 (61), 81 (77); HRMS: calcd for C15H20: 200.1565;
‡
found: 200.1540 [M] .
Compound (16a): 1H NMR (200 MHz, CDCl3): d ˆ 1.38 1.83 (m, 14H),
2.25 2.50 (m, 1H), 6.20 (dd, J ˆ 16, 6.6 Hz, 1H), 6.33 (d, J ˆ 16 Hz, 1H),
7.12 7.37 (m, 5H); 13C NMR (50 MHz, CDCl3): d ˆ 25.01, 25.93, 27.37,
31.80, 41.27, 125.98, 126.69, 126.87, 128.49, 137.89, 138.20; MS: m/z (%): 214
‡
83.75, 168.47, 168.84; MS: m/z (%): 244 (0.3) [M] , 149 (47), 105 (35), 71
‡
(100); HRMS: calcd for C12H20O5: 244.1311, found 244.1292 [M] .
‡
(4) [M] , 120 (45), 105 (100), 91 (40).
Synthesis of styryl-(1,3)-dioxolane [(E)-18]: The procedure given above
was used with the precursor of radical 17 (10 mL), and the starting
materials 1a,b, f h (1 mmol) under the specified conditions shown in
Table 5.
Acknowledgement
Financial support by the National Science Council of the Republic of China
(NSC 90-2113-M-003-013) is gratefully acknowledged.
Compound (18a): 1H NMR (200 MHz, CDCl3): d ˆ 3.92 3.95 (m, 2H),
4.02 4.06 (m, 2H), 5.42 (d, J ˆ 6.4 Hz, 1H), 6.16 (dd, J ˆ 16, 6.0 Hz,
1H),6.77 (d, J ˆ 16 Hz, 1H), 7.25 7.42 (m, 5H); 13C NMR (50 MHz,
CDCl3): d ˆ 64.95, 103.76, 125.12, 126.85, 128.25, 128.49, 134.70, 135.77;
[1] A. J. Clark, S. Rooke, T. J. Sparey, P. C. Taylor, Tetrahedron Lett. 1996,
37, 909 912.
[2] J. Xiang, P. L. Fuchs, J. Am. Chem. Soc. 1996, 118, 11986 11987.
[3] J.-T. Liu, C.-F. Yao, Tetrahedron Lett. 2001, 42, 6047 6050, and
references therein.
[4] T. Kawashima, M. Nakamura, N. Inamoto, Phosphorus, Sulfur Silicon
1992, 69, 293 297; T. Kawashima, M. Nakamura, N. Inamoto, Hetero-
cycles 1997, 44, 487 508.
[5] a) C.-F. Yao, C.-M. Chu, J.-T. Liu, J. Org. Chem. 1998, 63, 719 722;
b) J.-T. Liu, Y.-J. Jang, Y.-K. Shih, S.-R. Hu, C.-M. Chu, C.-F. Yao, J.
Org. Chem. 2001, 66, 6021 6028.
‡
MS: m/z (%): 176 (3.6) [M] , 131 (100), 103 (65), 77 (56); HRMS: calcd for
‡
C11H12O2: 176.0838; found: 176.0865 [M] .
Compound (18b): 1H NMR (200 MHz, CDCl3): d ˆ 3.89 3.98 (m, 2H),
3.98 4.08 (m, 2H), 5.40 (d, J ˆ 5.8 Hz, 1H), 6.13 (dd, J ˆ 16, 5.8 Hz,
1H),6.71 (d, J ˆ 16 Hz, 1H), 7.25 7.35 (m, 4H); 13C NMR (50 MHz,
CDCl3): d ˆ 64.94, 103.49, 125.84, 128.07, 128.72, 133.38, 133.96, 134.29;
‡
MS: m/z (%): 210 (1) [M] , 182 (64), 139 (100), 102 (58); HRMS: calcd for
‡
C11H11O2Cl: 210.0448, found 210.0422 [M] .
Compound (18 f): 1H NMR (200 MHz, CDCl3): d ˆ 3.81 (s, 3H), 3.90 3.99
(m, 2H), 4.02 4.10 (m, 2H), 5.40 (d, J ˆ 6.2 Hz, 1H), 6.03 (dd, J ˆ 16,
6.2 Hz, 1H), 6.72 (d, J ˆ 16 Hz, 1H), 6.82 6.89 (m, 2H), 7.32 7.39 (m,
2H); 13C NMR (50 MHz, CDCl3): d ˆ 55.23, 65.00, 104.23, 114.01, 122.79,
[6] W. K. Busfield, I. D. Grice, I. D. Jenkins, J. Chem. Soc. Perkin Trans. 2
1994, 1079 1086.
‡
128.28, 130.41, 134.64, 159.87; MS: m/z (%): 206 (25) [M] , 147 (40), 134
Received: November 11, 2002 [F4571]
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Chem. Eur. J. 2003, 9, 2123 2128