Novel synthesis of alkenes via triethylborane-induced free-radical reactions of alkyl iodides and β-nitrostyrenes

Article abstract of DOI:10.1021/jo010213m

Reactions of (E)-β-nitrostyrenes 1 and triethylborane 2 or tricyclohexylborane 4 in THF solution at room temperature in the presence of oxygen in the air as radical initiator generate high yields of trans-alkenes (E)-3 or (E)-5. Medium to high yields of d

Full text of DOI:10.1021/jo010213m

J . Org. Chem. 2001, 66, 6021-6028
6021
Novel Syn th esis of Alk en es via Tr ieth ylbor a n e-In d u ced
F r ee-Ra d ica l Rea ction s of Alk yl Iod id es a n d â-Nitr ostyr en es
J u-Tsung Liu, Yeong-J iunn J ang, Yuh-Kuo Shih, Shin-Ru Hu, Cheng-Ming Chu, and
Ching-Fa Yao*
Department of Chemistry, National Taiwan Normal University, 88, Sec. 4, Tingchow Road,
Taipei, Taiwan 116, Republic of China
cheyaocf@scc.ntnu.edu.tw
Received February 26, 2001
Reactions of (E)-â-nitrostyrenes 1 and triethylborane 2 or tricyclohexylborane 4 in THF solution
at room temperature in the presence of oxygen in the air as radical initiator generate high yields
of trans-alkenes (E)-3 or (E)-5. Medium to high yields of different (E)-alkenes (E)-5, 7, 10, 12, and
1
6
4 also can be prepared when 1 reacts with different radicals, prepared from secondary alkyl iodides
and 8 or tertiary alkyl iodides 9, 11, and 13, in the presence of 2 and air as radical initiator. The
generation of the only product (E)-alkenes can be explained by the generation of the benzylic radical
A and/or B as the intermediate only and the mechanism is similar to Scheme 1. Both (E)- and
(Z)-16a -c are generated when (E)- and (Z)-15a -c are used to react with adamantyl radical under
similar conditions. Only (Z)-16d was observed when either (E)- or (Z)-15d was used to react with
adamantyl radical. The generation of the (E)- and/or (Z)-alkenes can be explained by the free rotation
of the A and/or B to generate A′ and/or B′ and vice versa, and the mechanism is proposed to be a
2
free-radical reaction via NO /alkyl substitution and is shown as Scheme 2.
In tr od u ction
nitrogen or by photolysis in the presence of tert-butyl
peroxide as radical initiator. All these results indicate
8
Nitro olefins are useful intermediates in organic syn-
thesis and are important structural units that can be
used as starting materials for many classes of com-
that â-nitrostyrenes can react with different organome-
tallic reagents to generate nitroalkanes or alkenes under
different conditions and workup procedures and the
1
pounds. Reactions of â-nitrostyrenes with organometallic
reaction mechanism is proposed to be a free-radical and/
2
a
2b,c
reagents such as dialkylzinc or organozinc halides,
1-8
or an ionic reaction.
In this paper, we wish to report
t-BuHgX/KI,3 organomanganese,4 trialkylgallium, tri-
alkylaluminum or dialkylaluminum chloride, and Grig-
5
an improved and effective method, based on our previous
6
study,8 to synthesize different alkenes by reaction of
nard reagents,7 respectively, generate alkenes and/or
nitroalkanes or halooximes have been reported. Our
previous study found that medium to high yields of
alkenes can be generated when (E)-â-nitrostyrenes 1
react with triethylborane in THF solution under refluxing
condition in the presence of a trace of oxygen in the
â-nitrostyrenes with different radicals that were prepared
from alkyl iodides and triethylborane in the presence of
oxygen in the air as radical initiator.
Resu lts a n d Discu ssion
At room temperature, (E)-â-nitrostyrenes 1 reacted
with triethylborane 2 or tricyclohexylborane 4 in THF
solution in the presence of oxygen in the air to generate
87-100% of 1-aryl-1-butene 3 or 79-98% of 1-aryl-2-
cyclohexylethene 5 within 5-10 min (eq 1 and Table 1).
All spectral data indicate that the alkenes have (E)
configuration (J trans ) 16.0 Hz for vinyl hydrogen) after
the mixture were purified by flash column chromatog-
raphy and the spectral data of the known products are
also consistent with literature report.2 Compared to our
previous study to stimulate the reaction by refluxing or
(
1) (a) Corey, E. J .; Estreicher, H. J . Am. Chem. Soc. 1978, 100, 6294.
(
b) Seebach, D.; Colvin, E. W.; Weller, T. Chimia 1979, 33, 1. (c)
Barrett, A. G. M.; Graboski, G. G. Chem. Rev. 1986, 86, 751. (d) Rosini,
G.; Ballini, R. Synthesis 1988, 833. (e) Nitroalkanes and Nitroalkenes
in Synthesis. Tetrahedron 1990, 46, 7313. (f) Barrett, A. G. M. Chem.
Soc. Rev. 1991, 20, 95.
(2) (a) Seebach, D.; Schafer, H.; Schmidt, B.; Schreiber, M. Angew.
Chem., Int. Ed. Engl. 1992, 31, 1587. (b) Hu, Y.; Yu, J .; Yang, S.; Wang,
J .-X.; Yin, Y. Synlett. 1998, 1213. (c) Hu, Y.; Yu, J .; Yang, S.; Wang,
J .-X.; Yin, Y. Synth. Commun. 1999, 29, 1157.
(
(
3) Russell, G. A.; Yao, C.-F. Heteroatom Chem. 1992, 3, 209.
4) Namboothiri, I. N. N.; Hassner, A. J . Organomet. Chem. 1996,
,8
5
18, 69.
(
347.
5) Han, Y.; Huang, Y.-Z.; Zhou, C.-M. Tetrahedron Lett. 1996, 37,
8
by photolysis the solution, the reaction condition of this
3
(
6) Chu, C.-M.; Liu, J .-T.; Lin, W.-W.; Yao, C.-F. J . Chem. Soc.,
Perkin Trans. 1 1999, 47.
7) (a) Kohler, E. P.; Stone, J . R. J . Am. Chem. Soc. 1930, 52, 761.
b) Buckley, G. D. J . Chem. Soc. 1947, 1494. (c) Buckley, G. D.; Ellery,
method is mild and easy to follow and the reaction rate
is also accelerated dramatically by the presence of the
oxygen in the air so that the reaction time can be reduced
from few hours to only 5-10 min. The mechanism is also
proposed to be a free-radical reaction proceeding through
an addition and elimination reaction to generate (E)-
(
(
E. J . J . Chem. Soc. 1947, 1497. (c) Ashwood, M. S.; Bell, L. A.;
Houghton, P. G.; Wright, S. H. B. Synthesis 1988, 379. (d) Yao, C.-F.;
Chen, W.-W.; Lin, Y.-M. Tetrahedron Lett. 1996, 37, 6399. (e) Yao, C.-
F.; Kao, K.-H.; Liu, J .-T.; Chu, C.-M.; Wang, Y.; Chen, W.-C.; Lin, Y.-
M.; Lin, W.-W.; Yan, M.-C.; Liu, J .-Y.; Chuang, M.-C.; Shiue, J .-L.
Tetrahedron 1998, 54, 791. (f) Liu, J .-T.; Lin, W.-W.; J ang, J .-J .; Liu,
J .-Y.; Yan, M.-C.; Hung, C.; Kao, K.-H.; Wang, Y.; Yao, C.-F. Tetra-
hedron 1999, 55, 7115.
8
alkenes that are similar to our previous report.
(8) Yao, C.-F.; Chu, C.-M.; Liu, J .-T. J . Org. Chem. 1998, 63, 719.
1
0.1021/jo010213m CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/15/2001

6
022 J . Org. Chem., Vol. 66, No. 18, 2001
Liu et al.
Ta ble 2. Rea ction of tr a n s-â-Nitr ostyr en es 1 (1 Equ iv)
w ith RI (Excess) a n d Et3B (3 Equ iv) in THF in th e
P r esen ce of Oxygen u n d er a n Air Atm osp h er e
entry
1
RI (equiv)
product (yield %)a
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
1a
1b
1b
1b
1b
1c
1d
1e
1f
1a
1b
1c
1d
1e
1f
6 (12)
6 (12)
6 (12)
6 (12)
6 (12)
6 (12)
6 (12)
6 (20)
6 (20)
8 (12)
8 (12)
8 (12)
8 (12)
8 (12)
8 (12)
9 (6)
7a (85)
7b (97)
7b (100)
7b (38)
7b (64)
7c (98)
7d (100)
7e (100)
7f (92)
5a (79)
5b (97)
5c (97)
5d (94)
5e (77)
5f (57)
10a (72)
10b (67)
10c (75)
10d (77)
10e (75)
10f (57)
b
c
d
e
1
1
1
1
1
1
1
1
e
Ta ble 1. Rea ction of tr a n s-â-Nitr ostyr en es 1 (1 Equ iv)
w ith R3B 2 or 4 (3 Equ iv) in THF u n d er a n Air
Atm osp h er e a t Room Tem p er a tu r e
e
e
e
entry
1
R3B
product
yield (%)a
e
1a
1b
1c
1d
1e
1f
1
2
3
4
5
6
7
8
9
0
1
2
3
4
1a
1b
1b
1b
1c
1d
1e
1f
1a
1b
1c
1d
1e
1f
2
2
2
2
2
2
2
2
4
4
4
4
4
4
3a
3b
3b
3b
3c
3d
3e
3f
5a
5b
5c
5d
5e
5f
96
100
tr
96
9 (6)
9 (6)
9 (6)
9 (6)
b
18
19
0
1
c
2
2
89
98
87
99
79
97
85
90
98
92
9 (6)
a
Isolated yields. b Pure oxygen was used. c One equivalent of
d
Et3B was used and 62% unreacted 1b was recovered. Two
equivalents of Et3B was used and 36% unreacted 1b was recov-
1
1
1
1
1
ered. e NMR yields.
Triethylborane not only can be served as one of the
methods for the generation of radical species but also can
be used as an effective radical initiator to generate
a
Isolated yields. b 50 mol % galvinoxyl was added and 92%
unreacted 1b was recovered. Pure oxygen was used.
c
different radicals by reaction of triethylborane with alkyl
iodides under mild conditions.1
0,11
On the basis of these
Other evidence to prove the free-radical reaction is that
the reaction is retarded or inhibited by the addition of
galvinoxyl, an efficient scavenger for free radicals. After
reports, we apply this methodology to â-nitrostyrenes by
using triethylborane and air as the free radical initiator
to induce alkyl iodide to generate different radicals. As
expected, good to excellent yields of alkenes (E)-7, 5, or
10 were generated within 5-10 min when 1 (1 equiv)
and excess alkyl iodides such as isopropyl iodide 6,
cyclohexyl iodide 8, or tert-butyl iodide 9 (6-20 equiv)
were put in the THF solution and then 2 (3 equiv) was
added into the THF solution slowly by syringe at room
temperature under similar conditions (eq 3 and Table 2).
9
addition of 50 mol % galvinoxyl under similar conditions,
only a trace of 3b was observed and 92% unreacted 1b
was recovered (Table 1, entry 3). Oxygen is not only
known to be a free-radical initiator but also is known to
be a radical scavenger. When the reaction was conducted
in pure oxygen, 96% 3b (Table 1, entry 4) was obtained,
which is lower than with the use of air (100%) under
similar procedures (Table 1, entry 2). These results
indicate that the use of air is good enough for these
reactions.
It has been found that 3 equiv of triethylborane 2 is
necessary to generate enough ethyl radical as radical
It has been reported that both (E)- and (Z)-1a react
(
(
9) Barlett, P. D.; Funahashi, T. J . Am. Chem. Soc. 1962, 84, 2596.
10) Smadja, W. Synlett 1994, 1.
with diethylzinc to give the (E)-3a only.2 In addition to
a
(
E)-1a , (Z)-1a was also used to react with 2 under similar
(11) (a) Suzuki, A.; Nozawa, S.; Harada, M.; Itoh, M.; Brown, H. C.;
Midland, M. M. J . Am. Chem. Soc. 1971, 93, 1508. (b) Nozaki, K.;
Oshima, K.; Utimoto, K. J . Am. Chem. Soc. 1987, 109, 2547. (c) Nozaki,
K.; Oshima, K.; Utimoto, K. Tetrahedron Lett. 1988, 29, 1041. (d)
Bertrand, M. P.; Feray, L.; Nouguier, R.; Perfetti, P. J . Org. Chem.
conditions as described above (eq 2). As expected, 90%
yield of the same product (E)-3a was also isolated, and
this result is actually consistent with literature report.2
a
1
999, 64, 9189. (e) Miyabe, H.; Ushiro, C.; Ueda, M.; Yamakawa, K.;
Naito, T. J . Org. Chem. 2000, 65, 176. (f) Wu, B.; Avery, B. A.; Avery,
M. A. Tetrahedron Lett. 2000, 41, 3797. (g) Miyabe, H.; Ueda, M.; Naito,
T. J . Org. Chem. 2000, 65, 5043. (h) Miyabe, H.; Fujii, K.; Goto, T.;
Naito, T. Org. Lett. 2000, 2, 4071. (i) Yorimitsu, H.; Nakamura, T.;
Shinokubo, H.; Oshima, K.; Omoto, K.; Fujimoto, H. J . Am. Chem. Soc.
2
000, 122, 11041.

Synthesis of Alkenes via Triethylborane-Induced Free-Radical Reactions
J . Org. Chem., Vol. 66, No. 18, 2001 6023
initiator to undergo further reactions. When 1 equiv of 2
was used, only 38% 7b and 62% unreacted 1b were found
in the crude NMR analysis (Table 2, entry 4). Similarly,
only 64% 7b and 36% unreacted 1b were found when 2
equiv of 2 was used (Table 2, entry 5). Similar to eq 2,
7
6% of 10a was also isolated when (Z)-1a reacted with 9
and 2 under similar conditions, and this result is also
good enough to prove that both (E)-1a and (Z)-1a can
react with the same radical to generate the same product
trans-alkene.
8
Compared to Table 1 and our previous study, we found
that the same or similar alkenes also could be prepared
easily just by adding alkyl iodides to the reaction mixture
under similar conditions. The condition of this improved
method is not only mild and convenient but this method
also can be used to synthesize high yield of alkenes with
three components in a one-pot reaction at room temper-
ature. For example, 57-77% (E)-10a -f (Table 2, entries
Ta ble 3. P r ep a r a tion of 14 by Rea ction of 1 (1 Equ iv), 13
(6 Equ iv), a n d 2 (3 Equ iv) in th e P r esen ce of Oxygen
yielda (%)
entry
1
14
1
2
3
4
5
6
1a
1b
1c
1d
1e
1f
14a
14b
14c
14d
14e
14f
71
60
99
86
82
1
6-21) were generated when 1 reacted with 9 and 2 as
described above. In addition to (E)-10a -f, 78% of the
same product (E)-3,3-dimethyl-1-(4-methylphenyl)-1-
8
100
butene that has been reported in our previous report also
a
was isolated when (E)-2-(4-methylphenyl)-1-nitroethene
reacted with 9 and 2 in THF solution in the presence of
the oxygen in the air but only 50% yield was observed
when the same starting material reacted with B-tert-
butyl-9-BBN in THF solution under refluxing condition
in the presence of a trace of oxygen in the nitrogen.8
Isolated yields.
be generated by using 11, 2, and air at room tempera-
ture.1
3,14
5-Substituted-2-adamantanones and their derivatives
are useful and interesting compounds for the study of
diastereoselectivities in the reactions of sterically unbi-
ased ketones.15 Many 5-substituted-2-adamantanones
with different withdrawing and donor groups such as CN,
It has been reported that different alkyl radicals
including 1-adamantyl radical and aryl radical can be
generated by the reduction of alkyl or aryl halides with
COOCH
3
, CF
3
, F, Cl, Br, I, OH, NMe
2 3 3
, OCH , OCOCH ,
(
ethylenediamine)chromium(II) complexes in dry dim-
1
5
1
2
CH , t-Bu, SiMe
3
3
, and SnMe have been prepared. On
3
ethylformamide. The palladium-catalyzed reaction of
-bromoadamantane with styrene and donor-substituted
the basis of eq 4, compounds 1 were also used to react
with 5-iodoadamantan-2-one 13 and 2 to yield 60-100%
of (E)-1-(4-oxoadamantyl)-2-arylethene (E)-14 under simi-
lar conditions (eq 5 and Table 3). The generation of 14
indicates that not only the alkyl radicals but the γ-keto
radical also could be produced by this useful methodology.
Steric hindrance is one of the effects to affect reactions
and always plays an important role in determining of the
intermediate and final product stability. After observa-
tion substrate 1, we then focus our study on the reactions
of steric hindered R-alkyl-â-nitrostyrenes such as (E)-15
and (Z)-15, prepared from the substitution of the R-hy-
1
styrenes give the corresponding Heck-type coupling
product (E)-1-adamantyl-2-arylethene in 15-41% also
has been reported by Br a¨ se et al.13 Similarly, Yamataka
and co-workers also have reported that both (Z)- and (E)-
1
-adamantyl-2-arylethene mixture had been prepared
from the Wittig reaction of substituted benzaldehydes
with (1-adamantylmethylidene)triphenylphosphorane.14
According to these reports and eq 3, it might be possible
to prepare similar products by reaction of 1 with 1-io-
doadamantane 11 under similar conditions. As expected,
when 1b (1 equiv) reacted with 11 (6 equiv) and 2 (3
equiv) in the presence of the oxygen within 5-10 min,
the only product is (E)-1-adamantyl-2-(4-methoxyphenyl)-
ethene 12 and the yield is 100% when the crude mixture
was analyzed by the proton NMR (eq 4). This result
indicates that the same adamantyl radical actually could
1
6
drogen of the â-nitrostyrenes 1 by different alkyl groups,
with 11 and 2 as described above (eq 6 and Table 4).
Surprisingly, not only (E)-16a but also (Z)-16a was
generated when either (E)-15a or (Z)-15a reacted with
1
1 and 2 under similar conditions, and the total yields
were 74% and 90%, respectively. The gas chromatogra-
phy analysis of the crude mixture found that the ratio of
(E)-16a to (Z)-16a approximately equal to 96:4 or 92:8
(
12) (a) Tashtoush, H. I.; Sustmann, R. Chem. Ber. 1992, 125, 287.
(
b) Tashtoush, H. I.; Sustmann, R. Chem. Ber. 1993, 126, 1759.
(
(
13) Br a¨ se S.; Waegell, B.; de Meijere, A. Synthesis 1998, 148.
14) Yamataka, H.; Takatsuka, T.; Hanafusa, T. J . Org. Chem. 1996,
6
1, 722.
15) (a) Gung, B. W.; le Noble, B. Chem. Rev. 1999, 99, 1067. (b)
Tomoda, S. Chem. Rev. 1999, 99, 1243. (c) Cieplak, A. S. Chem. Rev.
999, 99, 1265. (d) Ohwada, T. Chem. Rev. 1999, 99, 1337. (e) Gung,
(
1
B. W. Chem. Rev. 1999, 99, 1377. (f) Kaselj, M.; Chung, W.-S.; le Noble,
W. J . Chem. Rev. 1999, 99, 1387. (g) Adcock, W.; Trout, N. A. Chem.
Rev. 1999, 99, 1415. (h) Mehta, G.; Chandrasekhar, J . Chem. Rev. 1999,
9
9, 1437. (i) Wipf, P.; J ung, J .-K. Chem. Rev. 1999, 99, 1469. (j) Kao,
K.-H.; Sheu, R.-S.; Chen, Y.-S.; Lin, W.-W.; Liu, J .-T.; Yao, C.-F. J .
Chem. Soc., Perkin Trans. 1 1999, 283. (k) Tsai, T.-L.; Chen, W.-C.;
Yu, C.-H.; le Noble, W. J .; Chung, W.-S. J . Org. Chem. 1999, 64, 1099.

6
024 J . Org. Chem., Vol. 66, No. 18, 2001
Liu et al.
Sch em e 1
served when the vinyl hydrogen was irradiated and vice
versa.
According to literature reports2,6,8 and eqs 1-6, we can
conclude that the addition of the alkyl or adamantyl
radical to (E)-â-nitrostyrenes 1 generates benzylic radical
A and/or B and to (Z)-â-nitrostyrenes 1 generates benz-
ylic radical A′ and/or B′. The free rotation of the single
bond of A and/or B generate A′ and/or B′ and vice versa.
When R is the hydrogen, A and/or B is the only inter-
mediate to undergo elimination to yield (E)-alkene due
to the product stability of (E)-alkene is much more stable
than (Z)-alkene in energy. The reaction mechanism is
also proposed to proceed through an addition and elimi-
nation reaction, which is similar to Scheme 1. However,
both (E)-alkene and (Z)-alkene were generated when R
was the alkyl group (15a -d ) and the approaching radical
is adamantyl radical. A possible explanation is that the
steric hindrance between the adamantyl and the alkyl
group or the adamantyl and the aryl group becomes more
crowded so that this effect becomes more important in
the determination of the stability of the final product.
When R is the ethyl group (15a ), the product (E)-16a is
still more stable than (Z)-16a in energy so that only a
portion of the intermediate A and/or B converts into A′
and/or B′ when (E)-15a was used and most of the A′ and/
or B′ convert into A and/or B very fast before undergoing
elimination when (Z)-15a was used (Scheme 2). However,
when R is the cyclopentyl or cyclohexyl, the steric
hindrance between the cyclopentyl or cyclohexyl and the
adamantyl group is increased dramatically and this effect
can affect the product stability so that (Z)-16b-c are
much more stable than (E)-16b-c and become to be the
major products. These results indicate that A′ and/or B′
is the major intermediate and A and/or B is the minor
intermediate during the reaction no matter if (E)- or (Z)-
Ta ble 4. P r ep a r a tion of 16 by Rea ction of 15 (1 Equ iv),
1 (6 Equ iv), a n d 2 (3 Equ iv) in th e P r esen ce of Oxygen
1
entry
15
16
yielda (%)
E/Zb
1
2
3
4
5
6
7
8
(E)-15a
(Z)-15a
(E)-15b
(Z)-15b
(E)-15c
(Z)-15c
(E)-15d
(Z)-15d
16a
16a
16b
16b
16c
16c
16d
16d
74
90
59
50
73
63
35
32
96:4
92:8
32:68
37:63
18:82
13:87
<1:99c
<1:99c
a
Isolated yields. b GC ratio. c (E)-Product was not detected in
GCMS.
when (E)-15a or (Z)-15a was used (Table 4, entries 1 and
2
). The stereochemistry of (E)- and (Z)-16a can be
assigned by the NOE difference spectrum. Thus, only the
NOE enhancement of the aryl hydrogen was observed
when the vinyl hydrogen of (E)-16a was irradiated and
only the NOE enhancement of the ethyl hydrogen was
observed when the vinyl hydrogen of (Z)-16a was irradi-
ated. Under similar conditions, both (E)-16b and (Z)-16b
were observed in 59% or 50% yields when (E)-15b or (Z)-
1
1
1
5b was used to react with 11 and 2. The ratio of (E)-
6b to (Z)-16b approximately equal to 32:68 when (E)-
5b was used and approximately equal to 37:63 when
(
Z)-15b was used (Table 4, entries 3 and 4). The stereo-
chemistry of (E)- and (Z)-16b was also assigned by the
NOE difference spectrum. Similar to (E)- and (Z)-16a ,
only the NOE enhancement of the aryl hydrogen was
observed when the vinyl hydrogen of (E)-16b was irradi-
ated and only the NOE enhancement of the tertiary
hydrogen of the cyclopentyl group was observed when the
vinyl hydrogen of (Z)-16b was irradiated. After observa-
tion of substrates 15a -b, 15c-d were also checked as
described above. The results for 15c were similar to 15b.
The yields of (E)-16c and (Z)-16c were 73% and 63%, and
the ratio of (E)-16c to (Z)-16c was approximately equal
to 18:82 or 13:87 when (E)-15c or (Z)-15c was used (Table
1
1
5b-c was used. When R is the tert-butyl group, (Z)-
6d is the only product to be isolated when (E)-15d or
(Z)-15d was used. These interesting results indicate that
only A′ and/or B′ was generated during reaction even
though A and/or B also could be generated at the
beginning and this reactive intermediate can rotate to
generate A′ and/or B′ very fast due to the large steric
hindrance between tert-butyl and adamantyl group when
4
3
, entries 5 and 6). We were surprised to find that only
5% or 32% of (Z)-16d and some other products were
(E)-15d was used.
observed when the crude mixture was analyzed by the
NMR or GC/MS when (E)-15d or (Z)-15d was used to
react with adamantyl radical as described above (Table
In conclusion, we have developed an improved and easy
method for the synthesis of different (E)-alkenes by
reaction of (E)- or (Z)-â-nitrostyrenes with different
radicals, prepared from trialkylborane or alkyl iodide and
triethylborane, in the presence of the oxygen in the air
at room temperature. When R-alkyl-â-nitrostyrenes were
4
, entries 7 and 8). The stereochemistry of (Z)-16d also
can be assigned by the NOE difference spectrum. Thus,
NOE enhancement of the tert-butyl hydrogen was ob-

Synthesis of Alkenes via Triethylborane-Induced Free-Radical Reactions
J . Org. Chem., Vol. 66, No. 18, 2001 6025
3c,21b (E)-3d , (E)-3e, (E)-5a , (E)-5b, (E)-5e,24 (E)-7a ,20f,25
(
21a
8
8,22
23
Sch em e 2
E)-7b,2 (E)-10a ,
5a
25c,26
and (E)-10b
22b,26a
are all consistent with
the literature reports.
(
Z)-â-Nitr ostyr en e ((Z)-1a ).17 This compound was pre-
1
pared according to literature procedures: H NMR (200 MHz,
CDCl
J ) 9.6 Hz, 1H); C NMR (50 MHz, CDCl
30.71, 130.51, 129.91, 128.59; MS m/z (relative intensity) 149
3
) δ 7.54-7.37 (m, 5H), 6.98 (d, J ) 9.6 Hz, 1H), 6.79 (d,
13
3
) δ 135.76, 133.85,
1
+
(M , 58), 132 (19), 119 (6), 102 (77), 91 (62), 77 (100), 66 (19),
5
1 (39).
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
of Alk en es 3 or 5 fr om t h e R ea ct ion of (E)-â-Nit r o-
styr en es 1 a n d Tr ieth ylbor a n e 2 or Tr icycloh exylbor a n e
4
in THF Solu tion in th e P r esen ce of th e Oxygen in th e
Air (Equ a tion 1 a n d Ta ble 1). In a Pyrex test tube with a
magnetic stirrer were placed trans-â-nitrostyrene 1a (1 mmol)
and triethylborane 2 (3 mmol, 1.0 M in THF solution) in 8 mL
of THF, and the solution was bubbled with the air that filled
in the balloon. After 5-10 min, the solvent was evaporated
and the oily residue was purified by flash column chromatog-
raphy by using hexane to obtain 96% of (E)-3a . The spectral
data are all consistent with literature report.2
,8,20
All the
experimental results are shown in Table 1, and the spectral
data of other alkenes are shown as following.
(
E)-1-(4-Ch lor op h en yl)-1-bu ten e ((E)-3c):2 1H NMR
1b
(
200 MHz, CDCl
3
) δ 7.23 (s, 4H), 6.31 (d, J ) 15.6 Hz, 1H),
.21 (dt, J ) 15.6, 5.8 Hz, 1H), 2.21 (dq, J ) 7.4, 5.8 Hz, 2H),
.08 (t, J ) 7.4 Hz, 3H); 13C NMR (50 MHz, CDCl
) δ 136.51,
33.36, 132.32, 128.60, 127.72, 127.14, 25.92, 13.40; MS m/z
6
1
1
(
1
3
+
+
relative intensity) 168 ((M + 2) , 23), 166 (M , 69), 153 (25),
51 (73), 131 (100), 115 (77), 91 (21), 75 (13), 63 (13), 51 (11);
3
7
used, (E)- and/or (Z)-alkenes can be generated under
similar conditions. The generation of the different alkenes
can be explained by the generation of the different
intermediates during reaction and the different stability
of the final product in energy. The application of this
method would broaden the scope of utility of organo-
borane reagents in organic synthesis.
HRMS calcd for C10H11 Cl 168.0520, found 168.0519; calcd
3
5
for C10
E)-1-(N-P h en yl-3-in d olyl)-1-bu ten e ((E)-3f). This com-
pound is very unstable after isolation and decomposes at room
H11 Cl 166.0552, found 166.0549.
(
1
temperature: H NMR (200 MHz, CDCl
3
) δ 7.93-7.88 (m, 1H),
.57-7.20 (m, 9H), 6.61 (d, J ) 16.0 Hz, 1H), 6.31 (dt, J )
6.0, 6.4 Hz, 1H), 2.34-2.22 (m, 1H), 1.14 (t, J ) 7.4 Hz, 3H);
7
1
13
C NMR (50 MHz, CDCl ) δ 139.57, 136.61, 130.60, 129.60,
27.25, 126.42, 125.61, 124.31, 122.70, 120.61, 120.56, 120.26,
3
1
1
16.33, 110.62, 26.58, 14.01; MS m/z (relative intensity) 247
Exp er im en ta l Section
+
(M , 98), 232 (100), 217 (15), 206 (21), 193 (10), 180 (5), 165
Gen er a l Meth od s. All reactions were performed in flame-
or oven-dried glassware under a positive pressure of air.
Analytical thin-layer chromatography was performed with E.
Merck silica gel 60F glass plates and flash chromatography
by use of E. Merck silica gel 60 (230-400 mesh). MS or HRMS
were measured on J EOL J MS-D300 or J EOL J MS-HX110
(4), 154 (7), 128 (15), 115 (9), 104 (20), 77(17).
2
3
(E)-1-Cycloh exyl-2-(4-m eth oxyph en yl)eth en e ((E)-5b):
1
H NMR (200 MHz, CDCl ) δ 7.27 (dt, J ) 8.4, 2.2 Hz, 2H),
3
6.82 (dt, J ) 8.4, 2.2 Hz, 2H), 6.37 (d, J ) 16.0 Hz, 1H), 6.02
(dd, J ) 16.0, 6.8 Hz, 1H), 3.78 (s, 3H), 2.13-2.04 (m, 1H),
1
3
1.80-1.60 (m, 5H), 1.43-1.20 (m, 5H); C NMR (50 MHz,
1
13
spectrometers. H and C NMR spectra were recorded with a
Varian Gemini-200. All NMR data were obtained in CDCl
3
CDCl ) δ 158.69, 134.82, 130.97, 127.02, 126.60, 113.93, 55.21,
+
3
41.04, 33.03, 26.13, 26.01; MS m/z (relative intensity) 216 (M ,
50), 173 (33), 159 (28), 144 (11), 134 (100), 128 (11), 121 (48),
115 (21), 108 (21), 91 (22), 77 (10), 65 (8), 51 (5); HRMS calcd
solution, and chemical shifts (δ) are given in ppm relative to
TMS.
Ma ter ia ls. (E)-â-Nitrostyrenes 1a -f, triethylborane 2, 2-io-
dopropane 6, cyclohexyl iodide 8, 2-iodo-2-methylpropane 9,
and 1-iodoadamantane 11 were purchased from Aldrich Chemi-
cal Co., and other commercially available reagents were used
without further purification. Starting material (Z)-â-nitro-
for C15
(E)-1-Cycloh exyl-2-(4-ch lor op h en yl)eth en e ((E)-5c): 1H
NMR (200 MHz, CDCl ) δ 7.24 (s, 4H), 6.29 (d, J ) 16.2 Hz,
H20O 216.1514, found 216.1521.
3
(21) (a) J abri, N.; Alexakis, A.; Normant, J . F. Bull. Soc. Chim. Fr.
1
7
18
styrene 1a , tricyclohexylborane 4, 5-iodoadamantan-2-one
1983, II, 321. (b) Muraoka, K.; Nojima, M.; Kusabayashi, S.; Nagase,
S. J . Chem. Soc., Perkin Trans. 2 1986, 761. (c) Tanaka, J .; Nojima,
M.; Kusabayashi, S.; Nagase, S. J . Chem. Soc., Perkin Trans. 2 1987,
1
9
16
1
3, and (E)- and (Z)-15a -d were prepared according to the
2,8,20 20e,21
literature procedures. Products (E)-3a ,
(E)-3b,
(E)-
6
73.
22) (a) Hoshi, M.; Masuda, Y.; Arase, A. Bull. Chem. Soc. J pn. 1986,
(
(
(
16) Denmark, S. E.; Marcin, L. R. J . Org. Chem. 1993, 58, 3850.
17) (a) Miller, D. B.; Flanagan, P. W.; Shechter, H. J . Org. Chem.
59, 3985. (b) Baudin, J . B.; Hareau, G.; J ulia, S. A.; Lorne, R.; Ruel,
O. Bull. Soc. Chim. Fr. 1993, 130, 856. (c) Vedejs, E.; Fleck, T. J . J .
Am. Chem. Soc. 1989, 111, 5861. (d) Shen, Y.; Yao, J . J . Chem. Research
(S) 1996, 394. (e) Xiang, J .; J iang, W.; Gong, J .; Fuchs, P. L. J . Am.
Chem. Soc. 1997, 119, 4123.
1
1
976, 41, 2112. (b) Ohwada, T.; Ohta, T.; Shudo, K. J . Am. Chem. Soc.
986, 108, 3029. (c) Burdisso, M.; Gamba, A.; Gandolfi, R.; Perarello,
P. Tetrahedron 1987, 43, 1835.
(
(
18) Brown, H. C.; Racherla, U. S. J . Org. Chem. 1986, 51, 427.
19) (a) Geluk, H. W. Synthesis 1972, 374. (b) Adcock, W.; Trout, N.
(23) Alesso, E. N.; Tombari, D. G.; Moltrasio, G. Y.; Aguirre, J . M.
Can. J . Chem. 1987, 65, 2568.
A. J . Org. Chem. 1991, 56, 3229.
20) (a) Hauser, C. F.; Brooks, T. W.; Miles, M. L.; Raymond, M. A.;
(24) Kashihara, H.; Suemune, H.; Tsunehiro, N.; Sakai, K. Chem.
Pharm. Bull. 1990, 38, 2581.
(
Butler, G. B. J . Org. Chem. 1963, 28, 372. (b) Hill, E. A.; Engel, M. R.
J . Org. Chem. 1971, 36, 1356. (c) Fujiwara, Y.; Kuromaru, H.;
Taniguchi, H. J . Org. Chem. 1984, 49, 4309. (d) Bessmertnykh, A. G.;
Blinov, K. A.; Grishin, Y. K.; Donskaya, N. A.; Tveritinova, E. V.;
Yureva, N. M.; Beletskaya, I. P. J . Org. Chem. 1997, 62, 6069. (e)
Doering, W.; von E.; Benkhoff, J .; Carleton, P. S.; Pagnotta, M. J . Am.
Chem. Soc. 1997, 119, 10947.
(25) Buss, A. D.; Warren, S. J . Chem. Soc., Perkin Trans. 1 1985,
2307. (b) Kawashima, T.; Ishii, T.; Inamoto, N. Bull. Chem. Soc. J pn.
1987, 60, 1831. (c) Cahiez, G.; Avedissian, H. Synthesis 1998, 1199.
(26) (a) Yuan, T.-M.; Luh, T.-Y. J . Org. Chem. 1992, 57, 4550. (b)
Kirmse, W.; Konrad, W.; Schnitzler, D. J . Org. Chem. 1994, 59, 3821.
(c) Ishino, Y.; Mihara, M.; Nishihama, S.; Nishiguchi, I. Bull. Chem.
Soc. J pn. 1998, 71, 2669.

6
026 J . Org. Chem., Vol. 66, No. 18, 2001
Liu et al.
1
1
1
2
H), 6.12 (dd, J ) 16.2, 6.4 Hz, 1H), 2.23-2.04 (m, 1H), 1.83-
146 (14), 131 (10), 121 (15), 115 (14), 103 (7), 91 (28), 77 (12),
.60 (m, 5H), 1.44-1.03 (m, 5H); 13C NMR (50 MHz, CDCl
) δ
63 (8), 51 (9); HRMS calcd for C12
176.1201.
H16O 176.1200, found
3
58.69, 134.82, 130.97, 127.02, 126.60, 113.93, 41.04, 33.03,
+
(E)-3-Meth yl-1-(4-ch lor op h en yl)-1-bu ten e ((E)-7c): 1
H
6.13, 26.01; MS m/z (relative intensity) 222 ((M + 2) , 5), 220
+
(M , 15), 177 (6), 163 (4), 151 (6), 140 (33), 138 (100), 129 (23),
NMR (200 MHz, CDCl
3
) δ 7.25 (s, 4H), 6.29 (d, J ) 16.2 Hz,
1
15 (16), 103 (8), 95 (13), 77 (8), 67 (11), 51 (6); HRMS calcd
1H), 6.04 (dd, J ) 16.2, 6.2 Hz, 1H), 2.43 (oct, J ) 6.8 Hz,
3
7
35
13
for C14
H
16 Cl 221.0911, found 221.0919; calcd for C10
H
11 Cl
1H), 1.08 (d, J ) 6.8 Hz, 6H); C NMR (50 MHz, CDCl
3
) δ
2
19.0941, found 219.0940.
E)-1-Cycloh exyl-2-(2-th ien yl)eth en e ((E)-5d ): 1H NMR
200 MHz, CDCl ) δ 7.06 (d, J ) 4.8 Hz, 1H), 6.93 (dd, J )
.8, 2.8 Hz, 1H), 6.85 (d, J ) 2.8 Hz, 1H), 6.50 (d, J ) 15.8 Hz,
H), 6.10 (d, J ) 15.8, 6.8 Hz, 1H), 2.20-1.96 (m, 1H), 1.86-
138.75, 136.54, 132.32, 128.62, 127.22, 125.78, 31.44, 22.26;
+
+
(
MS m/z (relative intensity) 182 ((M + 2) , 11), 180 (M , 34),
167 (33), 165 (100), 145 (50), 130 (66), 125 (35), 115 (29), 101
(
3
4
1
1
1
2
1
6
1
13
(12), 89 (14), 75 (18), 63 (17), 51 (18); HRMS calcd for C11H -
3
5
Cl 180.0694, found 180.0706.
(E)-3-Meth yl-1-(2-th ien yl)-1-bu ten e ((E)-7d ): 1H NMR
(200 MHz, CDCl ) δ 7.07 (d, J ) 4.8 Hz, 1H), 6.93 (dd, J )
.60 (m, 5H), 1.44-1.02 (m, 5H); 13C NMR (50 MHz, CDCl
) δ
3
43.50, 136.84, 127.21, 124.20, 122.97, 120.67, 40.86, 32.74,
3
+
6.07, 25.92; MS m/z (relative intensity) 192 (M , 20), 149 (8),
4.8, 2.8 Hz, 1H), 6.87 (d, J ) 2.8 Hz, 1H), 6.47 (d, J ) 15.8 Hz,
1H), 6.10 (dd, J ) 15.8, 6.8 Hz, 1H), 2.41 (oct, J ) 6.8 Hz,
35 (17), 123 (9), 115 (10), 110 (100), 97 (16), 91 (10), 79 (8),
5 (5), 53 (3); HRMS calcd for C12
92.0974.
(
H
16S 192.0973, found
1H), 1.08 (d, J ) 6.6 Hz, 6H); 13C NMR (50 MHz, CDCl
) δ
3
143.38., 138.02, 127.24, 124.26, 123.05, 120.33, 31.27, 22.20;
E)-1-Cycloh exyl-2-(2-fu r yl)eth en e ((E)-5e):24 1H NMR
MS m/z (relative intensity) 153 [(M + 2) , 8], 152 [(M + 1) ,
61], 137 (100), 123 (6), 109 (7), 103 (14), 97 (39), 91 (14), 84
+
+
(200 MHz, CDCl
3
) δ 7.31-7.27 (m, 1H), 6.33 (dd, J ) 3.4, 1.8
Hz, 1H), 6.17-6.10 (m, 3H), 2.18-1.98 (m, 1H), 1.86-1.60 (m,
(3), 77 (10); HRMS calcd for C
(E)-1-(2-F u r yl)-3-m et h yl-1-bu t en e ((E)-7e): H NMR
(200 MHz, CDCl ) δ 7.30 (d, J ) 1.8 Hz, 1H), 6.34 (dd, J )
3.2, 1.8 Hz, 1H), 6.17-6.09 (m, 3H), 2.56-2.30 (m, 1H), 1.06
9
H11S 151.0582, found 151.0578.
H), 1.44-1.02 (m, 5H); 13C NMR (50 MHz, CDCl
) δ 153.65,
1
5
1
2
3
41.15, 135.82, 116.16, 111.09, 105.98, 40.74, 32.73, 26.07,
3
+
5.92; MS m/z (relative intensity) 176 (M , 18), 133 (5), 120
(4), 107 (5), 94 (100), 79 (11), 65 (7), 55 (8); HRMS calcd for
(d, J ) 6.6 Hz, 6H); 13C NMR (50 MHz, CDCl
) δ 153.56,
3
C
12
H
16O 176.1201, found 176.1199.
141.22, 137.07, 115.84, 111.11, 106.02, 31.14, 22.18; MS m/z
+
(
E)-1-Cycloh exyl-2-(N-p h en yl-3-in d olyl)eth en e ((E)-5f).
(relative intensity) 136 (M , 68), 121 (100), 107 (8), 103 (11),
This compound is very unstable after isolation and decomposes
91 (50), 81 (15), 77 (45); HRMS calcd for C
found 136.0880.
(E)-3-Meth yl-1-(N-p h en yl-3-in d olyl)-1-bu ten e ((E)-7f).
9
H12O 136.0888,
1
at room temperature: H NMR (200 MHz, CDCl
3
) δ 7.93-7.87
m, 1H), 7.59-7.36 (m, 9H), 6.57 (d, J ) 16.0 Hz, 1H), 6.22
dd, J ) 16.0, 7.0 Hz, 1H), 2.30-2.06 (m, 1H), 1.96-1.60 (m,
(
(
5
1
1
2
This compound is very unstable after isolation and decomposes
H), 1.46-1.16 (m, 5H); 13C NMR (50 MHz, CDCl
) δ 139.62,
at room temperature: H NMR (200 MHz, CDCl
1
) δ 7.93-7.88
3
3
36.64, 134.99, 129.62, 127.27, 126.43, 125.63, 124.34, 122.70,
20.53, 120.26, 118.95, 116.37, 110.64, 41.65, 33.26, 26.17,
(m, 1H), 7.55-7.19 (m, 9H), 6.57 (d, J ) 16.0 Hz, 1H), 6.24
(dd, J ) 16.0, 6.8 Hz, 1H), 2.60-2.46 (m, 1H), 1.49 (d, J ) 6.8
+
13
6.07; MS m/z (relative intensity) 301 (M , 100), 258 (40), 244
3
Hz, 6H); C NMR (50 MHz, CDCl ) δ 139.57, 136.63, 136.10,
(66), 230 (10), 219 (19), 206 (40), 193 (67), 180 (10), 167 (11),
129.60, 127.25, 126.42, 125.66, 124.31, 122.70, 120.54, 120.26,
1
28 (7), 115 (10), 104 (5), 77(10).
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
118.60, 116.25, 110.62, 31.97, 22.73; MS m/z (relative intensity)
261 (M , 60), 246 (100), 234 (22), 222 (32), 215 (10), 206 (14),
+
of 3a fr om th e Rea ction of (Z)-â-Nitr ostyr en e 1a a n d
Tr ieth ylbor a n e 2 in THF Solu tion in th e P r esen ce of th e
Oxygen in th e Air (Equ a tion 2). In a Pyrex test tube with
a magnetic stirrer were placed (Z)-â-nitrostyrene 1a (1 mmol)
and triethylborane 2 (3 mmol, 1.0 M in THF solution) in 8 mL
of THF, and the solution was bubbled with the air that filled
the balloon. After 5 min, the solvent was evaporated and the
oily residue was purified by flash column chromatography by
using hexane to obtain 90% of (E)-3a . The spectral data are
193 (12), 180 (5), 167 (9), 152 (4), 139 (3), 128 (8), 115 (8), 104
(8), 77(10).
(E)-3,3-Dim eth yl-1-p h en yl-1-bu ten e ((E)-10a ):25c,26 1H
NMR (200 MHz, CDCl
Hz, 1H), 6.23 (d, J ) 16.2 Hz, 1H), 1.12 (s, 9H); C NMR (50
MHz, CDCl ) δ 141.91, 138.11, 128.51, 126.78, 126.07, 124.63,
3
) δ 7.39-7.13 (m, 5H), 6.35 (d, J ) 16.2
13
3
+
33.27, 29.54; MS m/z (relative intensity) 160 (M , 64), 145
(100), 128 (31), 117 (56), 105 (20), 91 (50), 77 (17), 65 (10).
(E)-3,3-Dim eth yl-1-(4-m eth oxyp h en yl)-1-bu ten e ((E)-
2
,8,20
22b,26a 1
all consistent with literature reports.
10b):
3
H NMR (200 MHz, CDCl ) δ 7.29 (dt, J ) 8.8, 2.4
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
of Alk en es 7, 5, or 10 fr om th e Rea ction of tr a n s-â-
Nitr ostyr en es 1, Alk yl Iod id es 6, 8, or 9, a n d Tr ieth yl-
bor a n e 2 in THF Solu tion in th e P r esen ce of th e Oxygen
in th e Air (Equ a tion 3 a n d Ta ble 2). In a Pyrex test tube
with a magnetic stirrer were placed trans-â-nitrostyrene 1a
Hz, 2H), 6.84 (dt, J ) 8.8, 2.4 Hz, 2H), 6.26 (d, J ) 16.4 Hz,
1
3
1H), 6.11 (d, J ) 16.4 Hz, 1H), 3.80 (s, 3H), 1.10 (s, 9H);
NMR (50 MHz, CDCl
C
3
) δ 158.67, 139.78, 130.88, 127.07,
123.94, 113.91, 55.14, 33.11, 29.60; MS m/z (relative intensity)
190 (M , 64), 175 (100), 160 (27), 145 (15), 128 (14), 121 (28),
+
115 (22), 91 (20), 77 (10), 65 (6).
(1 mmol) and 2-iodopropane 6 (20 mmol) in 8 mL of THF, the
(E)-3,3-Dim et h yl-1-(4-ch lor op h en yl)-1-bu t en e
10c): 1H NMR (200 MHz, CDCl
) δ 7.26 (s, 4H), 6.23 (s, 2H),
1.10 (s, 9H); C NMR (50 MHz, CDCl ) δ 142.62, 136.67,
132.32, 128.62, 127.30, 123.58, 33.34, 29.47; MS m/z (relative
((E)-
solution was bubbled with the air that filled the balloon, and
then triethylborane 2 (3 mmol, 1.0 M in THF solution) was
slowly added into the solution by syringe. After 5-10 min, the
solvent was evaporated and the oily residue was purified by
flash column chromatography by using hexane to obtain 85%
of (E)-7a . All the experimental results are shown in Table 2.
3
1
3
3
+
+
intensity) 196 ((M + 2) , 16), 194 (M , 49), 181 (41), 179 (100),
159 (15), 151 (20), 144 (41), 128 (38), 115 (25), 101 (9), 89 (8),
75 (8), 63 (7), 57 (3); HRMS calcd for C14
3
7
H
16 Cl 196.0833,
2
0f,25
1
35
(
E)-3-Meth yl-1-p h en yl-1-bu ten e ((E)-7a ):
H NMR
found 196.0853; calcd for C10
(E)-3,3-Dim eth yl-1-(2-th ien yl)-1-bu ten e ((E)-10d ):
NMR (200 MHz, CDCl ) δ 7.07 (d, J ) 4.8 Hz, 1H), 6.93 (dd,
J ) 4.8, 2.8 Hz, 1H), 6.87 (d, J ) 2.8 Hz, 1H), 6.43 (d, J )
H11 Cl 194.0862, found 194.0869.
1
(200 MHz, CDCl
3
) δ 7.37-7.10 (m, 5H), 6.34 (d, J ) 16.0 Hz,
H
1
1
1
H), 6.17 (dd, J ) 16.0, 6.4 Hz, 1H), 2.45 (oct, J ) 6.4 Hz,
H), 1.08 (d, J ) 6.4 Hz, 6H); 13C NMR (50 MHz, CDCl
) δ
38.07, 132.68, 128.51, 126.92, 126.80, 126.02, 31.45, 22.37;
3
3
1
3
15.8 Hz, 1H), 6.10 (d, J ) 15.8 Hz, 1H), 1.10 (s, 9H); C NMR
(50 MHz, CDCl ) δ 143.55, 141.86, 127.24, 124.31, 123.02,
118.30, 33.34, 29.44; MS m/z (relative intensity) 166 (M , 51),
+
MS m/z (relative intensity) 146 (M , 32), 131 (100), 115 (19),
3
+
1
03 (7), 91 (50), 77 (11), 65 (7), 51 (11).
E)-3-Meth yl-1-(4-m eth oxyp h en yl)-1-bu ten e ((E)-7b):2
) δ 7.27 (dt, J ) 8.8, 2.0 Hz, 2H),
.82 (dt, J ) 8.8, 2.0 Hz, 2H), 6.29 (d, J ) 16.0 Hz, 1H), 6.04
dd, J ) 16.0, 6.4 Hz, 1H), 3.78 (s, 3H), 2.43 (dsept, J ) 6.4,
.8 Hz, 1H), 1.08 (d, J ) 6.8 Hz, 6H); 13C NMR (50 MHz,
CDCl ) δ 158.75, 136.00, 130.88, 127.07, 126.25, 113.96, 55.21,
1.38, 22.47; MS m/z (relative intensity) 176 (37), 161 (100),
5a
(
151 (100), 135 (8), 123 (10), 117 (16), 105 (8), 97 (23), 77 (7);
1
H NMR (200 MHz, CDCl
3
HRMS calcd for C10
(E)-1-(2-Fu r yl)-3,3-dim eth yl-1-bu ten e ((E)-10e): 1H NMR
(200 MHz, CDCl ) δ 7.30 (dd, J ) 2.0, 0.4 Hz, 1H), 6.34 (dd, J
) 3.2, 2.0 Hz, 1H), 6.24 (d, J ) 16.2 Hz, 1H), 6.14 (dd, J )
H14S 166.0816, found 166.0813.
6
(
6
3
1
3
3
3.2, 0.4 Hz, 1H), 6.12 (d, J ) 16.2 Hz, 1H), 1.10 (s, 9H);
C
3
NMR (50 MHz, CDCl ) δ 153.68, 141.19, 140.92, 113.84,
3

Synthesis of Alkenes via Triethylborane-Induced Free-Radical Reactions
J . Org. Chem., Vol. 66, No. 18, 2001 6027
3
5
1
11.14, 106.12, 33.15, 29.41; MS m/z (relative intensity) 150
288.1095, found 288.1107; calcd for C18
found 286.1126.
H19O Cl 286.1124,
+
(
M , 46), 135 (100), 117 (14), 107 (24), 91 (39), 79 (25), 55 (17);
HRMS calcd for C10 14O 150.1045, found 150.1044.
E)-3,3-Dim eth yl-1-(N-p h en yl-3-in d olyl)-1-bu ten e ((E)-
0f). This compound is very unstable after isolation and
H
(E )-1-(4-Oxoa d a m a n t yl)-2-(2-t h ie n yl)e t h e n e
((E )-
) δ 7.11 (d, J ) 5.0 Hz, 1H),
14d ): 1H NMR (200 MHz, CDCl
(
3
1
6.96-6.89 (m, 2H), 6.44 (d, J ) 16.2 Hz, 1H), 5.95 (d, J ) 16.2
Hz, 1H), 2.60 (br s, 2H), 2.20 (br s, 1H), 2.05-1.88 (m, 10H);
1
decomposes at room temperature: H NMR (200 MHz, CDCl
δ 7.94-7.89 (m, 1H), 7.55-7.19 (m, 9H), 6.54 (d, J ) 16.2 Hz,
H), 6.33 (d, J ) 16.2 Hz, 1H), 1.18 (s, 9H); 13C NMR (50 MHz,
CDCl ) δ 140.00, 139.59, 136.64, 129.59, 127.28, 126.40, 125.61,
24.29, 122.68, 120.51, 120.21, 116.27, 110.62, 33.46, 29.77;
3
)
1
3
C NMR (50 MHz, CDCl ) δ 217.81, 142.74, 137.98, 127.33,
3
1
125.01, 123.56, 119.85, 46.20, 43.12, 40.89, 38.46, 34.96, 27.57;
+
MS m/z (relative intensity) 258 (M , 100), 187 (48), 153 (21),
135 (14), 115 (9), 97 (17), 77 (8); HRMS calcd for C16
258.1078, found 258.1079.
3
1
H
18OS
+
MS m/z (relative intensity) 275 (M , 43), 260 (100), 244 (18),
30 (11), 217 (8), 204 (6), 193 (5), 180 (2), 167 (5), 128 (4), 115
1
2
(E)-1-(4-Oxoa d a m a n tyl)-2-(2-fu r yl)eth en e ((E)-14e): H
(7), 104 (3), 77(6).
NMR (200 MHz, CDCl
3
) δ 7.30 (dd, J ) 2.0, 0.8 Hz, 1H), 6.36
(
2
dd, J ) 3.2, 2.0 Hz, 1H), 6.19-6.09 (m, 3H), 2.60 (br s, 2H),
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
.22 (br s, 1H), 2.05-1.86 (m, 10H); 13C NMR (50 MHz, CDCl
)
3
of 12 fr om th e Rea ction of 1b, Iod oa d a m a n ta n e 11, a n d
Tr ieth ylbor a n e 2 in THF Solu tion in th e P r esen ce of
Oxygen (Equ a tion 4). In a Pyrex test tube with a magnetic
stirrer were placed 1b (1 mmol) and iodoadamantane 11 (6
mmol) in 8 mL of THF, the solution was bubbled with air that
filled the balloon, and then triethylborane 2 (3 mmol, 1.0 M
in THF solution) was slowly added into the solution by syringe.
After 10 min, the solvent was evaporated and the oily residue
was purified by flash column chromatography by using hexane
to obtain 100% of (E)-12.
δ 217.89, 152.92, 141.51, 136.90, 115.16, 112.21, 107.04, 46.17,
4
2
7
3.08, 40.81, 38.43, 34.75, 27.54; MS m/z (relative intensity)
+
42 (M , 100), 171 (24), 143 (21), 128 (17), 115 (12), 91 (17),
H O 242.1307, found 242.1310.
18 2
E )-1-(4-Oxoa d a m a n t yl)-2-(N -p h e n yl-3-in d olyl)e t h -
7 (11); HRMS calcd for C16
(
en e ((E)-14f). This compound is very unstable after isolation
and decomposes at room temperature: 1H NMR (200 MHz,
CDCl
6.4 Hz, 1H), 6.15 (d, J ) 16.4 Hz, 1H), 2.61 (br s, 2H), 2.20
br s, 1H), 2.02-1.85 (m, 10H); 13C NMR (50 MHz, CDCl
) δ
218.13, 139.38, 136.66, 136.14, 129.60, 127.01, 126.55, 126.04,
3
) δ 7.90-7.80 (m, 1H), 7.55-7.17 (m, 9H), 6.52 (d, J )
1
(
3
(
E)-1-Ad a m a n t yl-2-(4-m et h oxyp h en yl)et h en e
((E)-
1
1
2
5
1
1
2
2): H NMR (200 MHz, CDCl
3
) δ 7.28 (dt, J ) 8.4, 1.0 Hz,
1
4
24.29, 122.81, 120.65, 120.04, 118.09, 115.72, 110.70, 46.37,
3.52, 41.23, 38.54, 35.06, 27.71; MS m/z (relative intensity)
367 (M , 100), 296 (37), 256 (23), 243 (9), 232 (8), 218 (10),
06 (9), 193 (7), 180 (7), 165 (5), 115 (5), 91 (6), 77(8).
H), 6.82 (dt, J ) 8.4, 1.0 Hz, 2H), 6.19 (d, J ) 16.2 Hz, 1H),
.96 (d, J ) 16.2 Hz, 1H), 3.78 (s, 3H), 2.01 (br s, 3H), 1.79-
+
1
3
.62 (m, 10H); C NMR (50 MHz, CDCl ) δ 158.64, 140.18,
3
2
31.03, 127.04, 123.82, 113.90, 55.24, 42.29, 36.84, 34.96,
+
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
8.45; MS m/z (relative intensity) 268 (M , 100), 211 (37), 159
of (E)-16 or (Z)-16 fr om th e Rea ction of (E)-15 or (Z)-15
a n d Iod oa d a m a n ta n e 11 in THF Solu tion in th e P r es-
en ce of Tr ieth ylbor a n e 2 a n d Oxygen (Equ a tion 6 a n d
Ta ble 4). In a Pyrex test tube with a magnetic stirrer were
placed (E)-15a (0.93 mmol) and 5-iodo-2-adamantane 11 (6
mmol) in 8 mL of THF, the solution was bubbled with the air
that filled the balloon, and then triethylborane 2 (3 mmol, 1.0
M in THF solution) was slowly added into the solution by
syringe. After 5-10 min, the solvent was evaporated and the
oily residue was purified by flash column chromatography by
using hexane to obtain 74% of (E)-16a and (Z)-16a . The ratio
of (E)-16a to (Z)-16a was approximately equal to 96:4 when
the crude mixture was analyzed by the gas chromatography.
Similar procedures were repeated as described above when (Z)-
(
24
14), 121 (24), 91 (18), 77 (10); HRMS calcd for C19H O
2
68.1827, found 268.1861.
Typ ica l Exp er im en ta l P r oced u r es for th e Syn th esis
of 14 fr om th e Rea ction of (E)-â-Nitr ostyr en es 1 a n d
-Iod o-2-a d a m a n ta n on e 13 in THF Solu tion in th e P r es-
en ce of Tr ieth ylbor a n e 2 a n d Air (Equ a tion 5 a n d Ta ble
5
3
1
). In a Pyrex test tube with a magnetic stirrer were placed
a (1 mmol) and 5-iodo-2-adamantanone 13 (6 mmol) in 8 mL
of THF, the solution was bubbled with the air that filled the
balloon, and then triethylborane 2 (3 mmol, 1.0 M in THF
solution) was slowly added into the solution by syringe. After
5
-10 min, the solvent was evaporated and the oily residue
was purified by flash column chromatography by using hexane
to obtain 71% of 14a . All the experimental results are shown
in Table 3.
E)-1-(4-Oxoa d a m a n tyl)-2-p h en yleth en e ((E)-14a ): 1
NMR (200 MHz, CDCl ) δ 7.39-7.16 (m, 5H), 6.30 (d, J ) 16.2
Hz, 1H), 6.09 (d, J ) 16.2 Hz, 1H), 2.61 (br s, 2H), 2.21 (br s,
1
1
4
1
1
2
1
5a was used to obtain the same product in 90% yield and
the ratio of (E)-16a to (Z)-16a approximately equal to 92:8 by
GC analysis.
(
H
3
(
E )-2-Cyclop e n t yl-2-(4-m e t h oxyp h e n yl)-1-n it r oe t h -
en e ((E)-15b). This compound was prepared according to the
1
3
H), 2.04-1.93 (m, 10H); C NMR (50 MHz, CDCl
3
) δ 217.96,
15 1
literature procedures: H NMR (200 MHz, CDCl
3
) δ 7.16 (dt,
38.25, 137.42, 128.56, 127.22, 126.29, 126.08, 46.28, 43.26,
1.00, 38.51, 34.93, 27.63; MS m/z (relative intensity) 252 (M ,
J ) 8.8, 2.2 Hz, 2H), 6.95 (s, 1H), 6.89 (dt, J ) 8.8, 2.2 Hz,
+
2
1
1
H), 4.01-3.74 (m, 1H), 3.82 (s, 3H), 2.02-1.90 (m, 2H), 1.71-
13
00), 194 (13), 181 (62), 167 (21), 153 (10), 141 (24), 128 (20),
.40 (m, 6H); C NMR (50 MHz, CDCl
3
) δ 160.13, 157.63,
15 (18), 103 (9), 91 (28), 77 (11); HRMS calcd for C18
52.1514, found 252.1513.
20
H O
36.82, 129.22, 128.45, 113.70, 55.20, 41.03, 31.17, 25.34; MS
+
m/z (relative intensity) 247 (M , 18), 216 (12), 201 (100), 185
(5), 173 (18), 159 (39), 147 (29), 133 (71), 121 (66), 115 (23),
103 (7), 91 (23), 77 (22); HRMS calcd for C H NO 247.1209,
(
E)-1-(4-Oxoadamantyl)-2-(4-methoxyphenyl)ethene ((E)-
1
1
2
5
3
4b): H NMR (200 MHz, CDCl ) δ 7.28 (dt, J ) 8.8, 2.2 Hz,
H), 6.84 (dt, J ) 8.8, 2.2 Hz, 2H), 6.24 (d, J ) 16.2 Hz, 1H),
.95 (d, J ) 16.2 Hz, 1H), 3.78 (s, 3H), 2.59 (br s, 2H), 2.19 (br
1
4
17
3
found 247.1202.
(Z)-2-Cyclop e n t yl-2-(4-m e t h oxyp h e n yl)-1-n it r oe t h -
en e ((Z)-15b). This compound was prepared according to the
1
3
s, 1H), 2.06-1.88 (m, 10H); C NMR (50 MHz, CDCl )δ 217.93,
3
1
4
2
58.90, 136.07, 130.07, 127.08, 125.52, 113.89, 55.09, 46.22,
literature procedures:15 1H NMR (200 MHz, CDCl ) δ 7.07 (dt,
3
3.27, 41.00, 38.42, 34.70, 27.55; MS m/z (relative intensity)
J ) 8.8, 2.2 Hz, 2H), 7.02 (s, 1H), 6.91 (dt, J ) 8.8, 2.2 Hz,
+
13
82 (M , 100), 211 (27), 197 (6), 181 (7), 171 (9), 159 (8), 141
2H), 3.95 (s, 3H), 2.89-2.73 (m, 1H), 1.88-1.35 (m, 8H);
C
(7), 128 (8), 121 (20), 91 (13), 77 (7); HRMS calcd for C19
H
22
O
2
NMR (50 MHz, CDCl ) δ 159.66, 155.38, 134.15, 128.54,
113.81, 113.70, 55.15, 47.37, 31.00, 24.40; MS m/z (relative
intensity) 247 (M , 66), 230 (8), 213 (15), 203 (24), 186 (14),
3
2
82.1620, found 282.1616.
+
(
E)-1-(4-Oxoa d a m a n tyl)-2-(4-ch lor op h en yl)eth en e ((E)-
1
1
1
4c): H NMR (200 MHz, CDCl
6.2 Hz, 1H), 6.06 (d, J ) 16.2 Hz, 1H), 2.62 (br s, 2H), 2.22
) δ
17.78, 138.92, 135.94, 132.79, 127.68, 127.31, 125.20, 46.22,
3.19, 40.92, 38.49, 35.00, 27.60; MS m/z (relative intensity)
3
) δ 7.28 (s, 4H), 6.26 (d, J )
175 (45), 159 (41), 147 (30), 135 (33), 128 (27), 121 (100), 115
(43), 108 (13), 91 (32), 77 (29); HRMS calcd for C14
247.1209, found 247.1208.
H17NO
3
1
3
(br s, 1H), 2.06-1.88 (m, 10H); C NMR (50 MHz, CDCl
3
2
4
2
2
(E)-2-Cycloh exyl-2-(4-m et h oxyp h en yl)-1-n it r oet h en e
((E)-15c). This compound was prepared according to the
+
+
15 1
88 ((M + 2) , 37), 286 (M , 100), 230 (4), 228 (12), 217 (18),
15 (47), 179 (18), 165 (18), 153 (10), 141 (14), 125 (17), 115
3
literature procedures: H NMR (200 MHz, CDCl ) δ 7.16 (dt,
J ) 8.8, 2.2 Hz, 2H), 6.90 (dt, J ) 8.8, 2.2 Hz, 2H), 6.87 (s,
3
7
13
(13), 103 (6), 91 (11), 77 (10); HRMS calcd for C18
H
19O Cl
1H), 3.83 (s, 3H), 3.70-3.50 (m, 1H), 1.79-1.06 (m, 10H);
C

6
028 J . Org. Chem., Vol. 66, No. 18, 2001
Liu et al.
NMR (50 MHz, CDCl
3
) δ 160.00, 158.64, 136.14, 129.07,
1H), 3.79 (s, 3H), 3.34-3.21 (m, 1H), 1.98 (br s, 3H), 1.86-
1
28.53, 113.57, 55.15, 40.07, 30.80, 26.02, 25.58; MS m/z
1.28 (m, 20H); 13C NMR (50 MHz, CDCl
3
) δ 157.88, 143.26,
+
(
1
(
relative intensity) 261 (M , 17), 215 (100), 199 (5), 185 (6),
73 (27), 159 (30), 147 (29), 133 (81), 121 (82), 115 (25), 107
13), 91 (21), 77 (15); HRMS calcd for C15 261.1365,
141.06, 136.83, 130.54, 112.64, 55.14, 43.44, 42.04, 36.87,
+
34.96, 31.50, 28.94, 25.01; MS m/z (relative intensity) 336 (M ,
H
19NO
3
52), 267 (27), 201 (40), 187 (17), 171 (26), 159 (10), 147 (7),
135 (100), 121 (23), 107 (8), 93 (15), 79 (18); HRMS calcd for
found 261.1370.
(
Z)-2-Cycloh exyl-2-(4-m et h oxyp h en yl)-1-n it r oet h en e
C
24
H
32O 336.2453, found 336.2453.
(Z)-1-Ad a m a n t yl-2-cyclop e n t yl-2-(4-m e t h oxyp h e n -
yl)eth en e ((Z)-16b): 1H NMR (200 MHz, CDCl
) δ 6.94 (dt,
(
(Z)-15c). This compound was prepared according to the
1
5 1
literature procedures: H NMR (200 MHz, CDCl
J ) 8.8, 2.2 Hz, 2H), 6.95 (s, 1H), 6.90 (dt, J ) 8.8, 2.2 Hz,
H), 3.82 (s, 3H), 2.36-2.25 (m, 1H), 1.83-1.14 (m, 10H); 13
NMR (50 MHz, CDCl ) δ 159.70, 156.73, 134.61, 128.31,
28.12, 113.77, 55.11, 45.61, 31.24, 26.11, 25.69; MS m/z
relative intensity) 261 (M , 54), 217 (25), 199 (13), 189 (12),
73 (17), 160 (25), 147 (33), 135 (43), 121 (100), 115 (31), 108
11), 91 (23), 77 (20); HRMS calcd for C15 261.1365,
3
) δ 7.05 (dt,
3
J ) 8.8, 2.2 Hz, 2H), 6.79 (dt, J ) 8.8, 2.2 Hz, 2H), 5.18 (s,
1H), 3.81 (s, 3H), 2.53-2.36 (m, 1H), 1.78 (br s, 3H), 1.78-
2
C
1.21 (m, 20H); 13C NMR (50 MHz, CDCl
) δ 157.93, 140.86,
3
3
1
(
1
(
136.81, 134.05, 130.82, 112.43, 55.08, 51.21, 43.49, 36.72,
35.38, 31.41, 28.62, 24.40; MS m/z (relative intensity) 336 (M ,
54), 267 (29), 201 (41), 187 (20), 171 (27), 159 (10), 147 (7),
135 (100), 121 (22), 107 (8), 93 (16), 79 (17); HRMS calcd for
+
+
H19NO
3
found 261.1365.
C
24
H
32O 336.2453, found 336.2456.
(
E)-2-ter t-Bu tyl-2-(4-m eth oxyph en yl)-1-n itr oeth en e ((E)-
(E )-1-Ad a m a n t y l-2-c y c lo h e x y l-2-(4-m e t h o x y p h e n -
1
1
5d ). This compound was prepared according to the literature
procedures: H NMR (200 MHz, CDCl
.2 Hz, 2H), 6.87 (dt, J ) 8.8, 2.2 Hz, 2H), 6.58 (s, 1H), 3.82
s, 3H), 1.21 (s, 9H); C NMR (50 MHz, CDCl
yl)eth en e ((E)-16c): H NMR (200 MHz, CDCl
3
) δ 7.00 (dt, J
1
5 1
3
) δ 7.09 (dt, J ) 8.8,
) 8.8, 2.2 Hz, 2H), 6.78 (dt, J ) 8.8, 2.2 Hz, 2H), 4.90 (s, 1H),
1
3
2
(
1
3.79 (s, 3H), 2.98-2.78 (m, 1H), 2.06-0.83 (m, 25H); C NMR
(50 MHz, CDCl ) δ 157.85, 146.40, 139.63, 137.07, 130.33,
1
3
3
) δ 159.32,
3
53.59, 136.00, 130.71, 129.18, 113.35, 55.20, 36.46, 29.15; MS
112.52, 55.14, 43.38, 41.01, 36.89, 34.93, 32.08, 28.82, 26.67,
+
+
m/z (relative intensity) 235 (M , 100), 220 (5), 203 (4), 189 (7),
74 (13), 159 (23), 147 (19), 132 (67), 121 (18), 115 (27), 103
10), 91 (20), 77 (16), 57 (85); HRMS calcd for C13
25.90; MS m/z (relative intensity) 350 (M , 73), 267 (35), 215
1
(
2
(64), 201 (27), 185 (4), 171 (22), 159 (9), 147 (10), 135 (100),
H
15NO
3
121 (24), 107 (9), 93 (16), 79 (17); HRMS calcd for C25
350.2610, found 350.2606.
34
H O
35.1208, found 235.1207.
Z)-2-ter t-Bu tyl-2-(4-m eth oxyph en yl)-1-n itr oeth en e ((Z)-
5d ). This compound was prepared according to the literature
(
(Z)-1-Ad a m a n t y l-2-c y c lo h e x y l-2-(4-m e t h o x y p h e n -
yl)eth en e ((Z)-16c): 1H NMR (200 MHz, CDCl
) δ 6.93 (dt,
J ) 8.8, 2.2 Hz, 2H), 6.79 (dt, J ) 8.8, 2.2 Hz, 2H), 5.12 (s,
1
3
1
5 1
procedures: H NMR (200 MHz, CDCl
dt, J ) 8.8, 2.2 Hz, 2H), 6.90 (dt, J ) 8.8, 2.2 Hz, 2H), 3.82 (s,
H), 1.16 (s, 9H); C NMR (50 MHz, CDCl
35.70, 128.77, 126.75, 113.40, 55.12, 36.75, 28.50; MS m/z
relative intensity) 235 (M , 98), 220 (3), 203 (4), 189 (6), 174
11), 159 (16), 147 (17), 132 (63), 121 (18), 115 (20), 103 (9), 89
24), 77 (16), 57 (100); HRMS calcd for C13H15NO 235.1208,
3
3
) δ 7.11 (s, 1H), 6.97
1
3
(
3
1
(
(
(
1H), 3.82 (s, 3H), 2.02-1.83 (m, 1H), 1.83-0.90 (m, 25H);
C
1
3
3
) δ 159.22, 159.13,
NMR (50 MHz, CDCl ) δ 157.90, 143.64, 136.69, 134.05,
130.73, 112.28, 55.06, 49.05, 43.45, 36.69, 35.28, 32.36, 28.59,
26.67, 26.07; MS m/z (relative intensity) 350 (M , 88), 267 (44),
3
+
+
215 (75), 201 (33), 185 (5), 171 (27), 159 (11), 147 (11), 135
(100), 121 (28), 107 (11), 93 (18), 79 (20); HRMS calcd for
found 235.1210.
E)-1-Adam an tyl-2-(3,4-dim eth oxyph en yl)-1-bu ten e ((E)-
C
25
H
34O 350.2610, found 350.2611.
(Z)-1-Ad a m a n t yl-2-t er t -b u t yl-2-(4-m e t h oxyp h e n yl)-
eth en e ((Z)-16d ): 1H NMR (200 MHz, CDCl
) δ 6.92 (dt, J )
(
1
1
(
6a ): H NMR (200 MHz, CDCl
s, 1H), 3.88 (s, 3H), 3.85 (s, 3H), 2.63 (q, J ) 7.4 Hz, 2H),
.99 (br s, 4H), 1.88-1.71 (m, 11H), 0.93 (t, J ) 7.4 Hz, 3H);
3
) δ 6.87-6.76 (m, 3H), 5.26
3
8.8, 2.2 Hz, 2H), 6.78 (dt, J ) 8.8, 2.2 Hz, 2H), 5.23 (s, 1H),
1
3.82 (s, 3H), 1.82-1.70 (m, 3H), 1.70-1.323 (m, 12H), 0.99 (s,
1
3
13
C NMR (50 MHz, CDCl
3
) δ 148.46, 147.78, 141.25, 138.33,
3
9H); C NMR (50 MHz, CDCl ) δ 157.94, 146.28, 135.03,
1
2
5
37.90, 119.00, 110.80, 110.41, 55.73, 43.00, 36.73, 35.08,
132.99, 131.86, 111.93, 55.09, 43.35, 36.72, 36.38, 35.28, 30.00,
+
+
8.74, 28.48, 23.81, 13.75; MS m/z (relative intensity) 326 (M ,
28.65; MS m/z (relative intensity) 324 (M , 32), 267 (100), 211
(3), 171 (9), 159 (6), 147 (10), 135 (79), 121 (11), 107 (8), 93
4), 311 (29), 295 (41), 201 (41), 135 (20), 91 (16), 79 (17);
HRMS calcd for C22
H
30
O
2
326.2245, found 326.2244.
(12), 79 (13); HRMS calcd for C23
324.2452.
H32O 324.2453, found
(
Z)-1-Adam an tyl-2-(3,4-dim eth oxyph en yl)-1-bu ten e ((Z)-
1
1
6a ): H NMR (200 MHz, CDCl
3
) δ 6.79 (d, J ) 8.4 Hz, 1H),
6
.65-6.61 (m, 2H), 5.13 (s, 1H), 3.89 (s, 3H), 3.87 (s, 3H), 2.14
Ack n ow led gm en t. Financial support by the Na-
tional Science Council of the Republic of China (NSC
(
q, J ) 7.4 Hz, 2H), 1.80 (br s, 3H), 1.62-1.46 (m, 12H), 0.92
13
(t, J ) 7.4 Hz, 3H); C NMR (50 MHz, CDCl
3
) δ 147.93, 147.31,
40.04, 136.69, 135.50, 121.20, 112.66, 110.18, 55.85, 55.70,
3.35, 36.69, 35.43, 35.37, 28.56, 13.19; MS m/z (relative
9
0-2113-M-003-013) is gratefully acknowledged.
1
4
Su p p or tin g In for m a tion Ava ila ble: 1H and 13C spectra
of compounds (Z)-1a , (E)-3c, (E)-3f, (E)-5b-f, (E)-7a -f, (E)-
+
intensity) 326 (M , 100), 311 (10), 295 (40), 201 (42), 135 (38),
9
3
1 (17), 79 (17); HRMS calcd for C22
26.2254.
30 2
H O 326.2245, found
1
1
0a -f, (E)-12, (E)-14a -f, (E)- and (Z)-15a -d , (E)- and (Z)-
6a -c, and (Z)-16d . This material is available free of charge
(
E )-1-Ad a m a n t yl-2-cyclop e n t yl-2-(4-m e t h oxyp h e n -
via the Internet at http://pubs.acs.org.
1
yl)eth en e ((E)-16b): H NMR (200 MHz, CDCl
J ) 8.8, 2.2 Hz, 2H), 6.78 (dt, J ) 8.8, 2.2 Hz, 2H), 5.01 (s,
3
) δ 7.02 (dt,
J O010213M