Radical reactions initiated by the photochemical cleavage of carbon-indium bonds of organoindium compounds

Article abstract of DOI:10.1016/j.tet.2008.01.013

Intra- and intermolecular reactions of carbon-centered radicals generated by photolysis of organoindium compounds were examined. The photolysis of vinylindium compounds and indium acetylides provided vinyl and alkynyl radicals, respectively, which were trapped with ethyl iodoacetate giving the corresponding β,γ-unsaturated esters. Allylic indium compounds, prepared from 8-bromo- or 8-iodooct-1,6-dienes and powdered indium metal, underwent an intramolecular radical cyclization to afford the 5-exo-trig product.

Full text of DOI:10.1016/j.tet.2008.01.013

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 2642e2650
www.elsevier.com/locate/tet
Radical reactions initiated by the photochemical cleavage of
carboneindium bonds of organoindium compounds
*
Tsunehisa Hirashita , Ayumi Hayashi, Makoto Tsuji, Jiro Tanaka, Shuki Araki
Omohi College, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
Received 15 November 2007; received in revised form 21 December 2007; accepted 2 January 2008
Available online 6 January 2008
Abstract
Intra- and intermolecular reactions of carbon-centered radicals generated by photolysis of organoindium compounds were examined. The
photolysis of vinylindium compounds and indium acetylides provided vinyl and alkynyl radicals, respectively, which were trapped with ethyl
iodoacetate giving the corresponding b,g-unsaturated esters. Allylic indium compounds, prepared from 8-bromo- or 8-iodooct-1,6-dienes and
powdered indium metal, underwent an intramolecular radical cyclization to afford the 5-exo-trig product.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
of organic radicals by a photolytic cleavage of carboneindium
bonds in organoindium compounds and subsequent intra- and
intermolecular additions to carbonecarbon double bonds.9
Organoindium compounds have hitherto been developed as
mild nucleophilic reagents in organic synthesis.1 Addition to
carbonyl compounds and imines is a typical reaction of allylin-
dium reagents, giving the corresponding homoallylic alcohols
and amines, respectively. Alkynes,2 allenes,3 and cyclopro-
penes4 also undergo allylindation to afford allylated products,
where a suitably introduced hydroxy group exerts significant ef-
fects on both acceleration and stereoselectivity of the allylation.
However, an addition to carbonecarbon double bonds without
a proper activation, such as substitution by electron-withdraw-
ing groups5 or introduction of a hydroxy group adjacent to the
double bond,6 has not been attained owing to the low nucleophi-
licity of organoindium compounds. Recently, indium-mediated
radical reactions have been reported, involving single electron
transfer (SET) reactions caused by metallic indium or reactions
of organoindium reagents with organic radicals.7 Although
photolysis of organoindium compounds leading to organic rad-
icals is documented for porphyrineindium complexes,8 photo-
chemical synthetic reactions dealing with organoindium
compounds remains unexplored. Here we report a generation
2. Results and discussion
2.1. Photochemical intermolecular reaction of organoindium
compounds
2.1.1. Allylic and benzylindium
Cinnamylindium sesquibromide, prepared from cinnamyl
bromide and indium, was irradiated with a high-pressure mer-
cury lamp (100 W, Pyrex filter) in THF, leading to a formation
of dimers 1 and 2 as the major products (Eq. 1). A small
amount of diol 3 (8%), which was coupled with THF, was
also isolated. Similarly, the irradiation of benzylindium ses-
quiiodide gave 1,2-diphenylethane (4) in 64% yield (Eq. 2).
Ph
Ph
+
1. In, reflux
2 h/THF
2. hυ, rt, 24 h
Ph
1
2
Ph
Ph
1 + 2: 33% (58:42)
ð1Þ
OH
Br
+
* Corresponding author. Tel./fax: þ81 52 735 5206.
E-mail address: hirasita@nitech.ac.jp (T. Hirashita).
Ph
OH
3: 8%
0040-4020/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.01.013

T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
2643
Table 2
Photochemical reaction of styrylindium 5a with 2-cyclohexenonea
1. In, rt, 2 h/DMF
2. hυ, rt, 20 h
PhCH2I
PhCH2CH2Ph
4: 64%
ð2Þ
O
O
Ph
+
5a
2.1.2. Vinylindium
8
We turned our attention on reactions of vinyl radicals gen-
erated from a homolytic cleavage of vinylindium compounds
by irradiation. Styrylindium was a choice of vinylindium com-
pounds. Lithiation of b-bromostyrene with t-BuLi at ꢀ78 ꢁC
followed by an addition of InCl3 gave styrylindium 5aec de-
pending on the amount of InCl3.7g
Entry
Conditions
Yield (%) (E/Z)b
1
2
3
4
a
rt, CH3CN
Reflux, THF
hn, THF
No reaction
No reaction
25 (43:57)
35 (37:63)
hn, CH3CN
The photochemical reaction of 5a with ethyl iodoacetate at
the stoichiometric molar ratio gave 6 in 56% yield with E/Z
ratio 86:14 (Table 1, entry 1). The yield of 6 was decreased
by shortening the irradiation time (entries 2 and 3). These facts
imply that the cleavage of the CeIn bond by irradiation is the
rate-determining step for this reaction, although the radical
chain mechanism cannot be excluded. The Et3B/O2-induced
radical reaction of stylylindium dichloride with ethyl iodoace-
tate has been reported,7f where the geometry of stylyl bromide
(E/Z¼1:99) was retained during the lithiationetransmetalla-
tion process; however, the radical reaction of ethyl iodoacetate
gave 6 in 93% yield as a mixture of geometric isomers (E/
Z¼35:65). These results indicate that the partial isomerization
(approximately 30%) occurred through the radical chain pro-
cess. We performed the photo-induced reaction of 5a using
Z-enriched stylyl bromide (E/Z¼8:92), which resulted in a for-
mation of 6 in 83% yield with E/Z ratio 56:44 (entry 4). The
formation of E-enriched 6 from Z-enriched 5a, even though
there is a possibility that the isomerization of Z to E occurs un-
der the irradiation conditions, can be rationalized by assuming
that the reaction proceeds via stylyl radical. The reaction of 5b
All reactions were performed overnight with styrylindium (2.0 mmol) and
2-cyclohexenone (1.0 mmol).
b
Determined by 1H NMR.
gave 6 in lower yield along with compound 7, which is derived
from the reaction of an enolate generated from 6 with ethyl
iodoacetate. Stylylindium 5c brought a further erosion of the
yields (entries 7 and 8). Although the precise mechanism under-
lying the radical reactions remains unclear at this stage, large
decreases in the yields with increasing the number of the or-
ganic groups on the indium atom were also observed in the rad-
ical reactions of organoindium compounds initiated by Et3B.7g
Next, photochemical reactions of styrylindium 5a with 2-
cyclohexenone were examined. The dark reaction of 5a with
2-cyclohexenone at room temperature or under reflux in
THF yielded no coupling product (Table 2, entries 1 and 2),
while under the irradiation conditions, the adduct 8 was ob-
tained in 25% yield (entry 3). The reaction in acetonitrile
gave better results (entry 4). These facts clearly show that
the cleavage of the Csp2 eIn bond occurred not by pyrolysis
but photolysis. In contrast to the reaction of ethyl iodoacetate,
the major geometry of 8 was Z. To confirm the isomerization of
E-8 to Z-8 during the irradiation, 8 (E/Z¼63:37) was irradiated
in acetonitrile for 15 h, which gave Z-enriched 8 (E/Z¼33:67)
quantitatively.
Table 1
Photochemical reaction of styrylindium compounds 5aec with ethyl
iodoacetatea
1. t-BuLi/Et2O
5a: n=1
2. InCl3/THF
InCl3-n
Br
5b: n=2
5c: n=3
Ph
Ph
2.1.3. Indium acetylide
n
(E/Z = 82:18)
Photochemical cleavage of a CspeIn bond was examined
with (phenylethynyl)indium 9aec. Lithiation of phenylacety-
lene with n-BuLi, followed by transmetallation with InCl3
gave a series of (phenylethynyl)indium compounds 9aec
according to the amount of InCl3 employed. The solution of 9
was irradiated in the presence of ethyl iodoacetate at room tem-
perature. The results are summarized in Table 3. (Phenylethyny-
l)indium dichloride 9a gave a coupling product 10 in 52% yield
and a small amount of 6 (Table 3, entry 1). A better yield was
obtained by increasing the amount of 9a (entry 2). Diorganoin-
dium 9b afforded 10 in 31% yield along with 6 (entry 3). When
the ratio of 9b was increased or triorganoindium 9c was em-
ployed, the reactions gave complicated mixtures (entries 4e6).
O
O
OEt
OEt
I
OEt
OEt
Ph
+
Ph
h
O
7
6
overnight
O
Entry
5
5/ICH2CO2Et
Yield (%)
6 (E/Z)b
7 (E/Z)b
1
2
3c
4
5
6
7
8
a
5a
5a
5a
5ad
5b
5b
5c
1:1
2:1
2:1
2:1
1:1
2:1
1:1
2:1
56 (86:14)
68 (85:15)
39 (91:9)
0
0
0
83 (56:44)
32 (86:14)
29 (100:0)
18 (87:13)
Complex mixture
0
12 (97:3)
19 (92:8)
0
2.2. Photochemical intramolecular reaction of organoindium
compounds
5c
Styrylindium compounds and ethyl iodoacetate were irradiated overnight.
Determined by 1H NMR.
Irradiation time was 2.5 h.
b
c
d
The difficulty observed in the intermolecular radical attack
toward a CeC double bond prompted us to examine the
Derived from b-bromostyrene (E/Z¼8:92).

2644
T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
Table 3
Photochemical reaction of indium acetylide 9aec with ethyl iodoacetatea
Table 4
Photochemical cyclization of 15aec
1. n-BuLi/THF
2. InCl3
t-BuLi
InCl3
h
R-Li
12
13 +14
R-Br
15
n-C5H12 / Et2O
−78 °C
THF
−78 °C
18 h
Ph
nInCl3-n
Ph
H
11
9a: n = 1, 9b: n = 2, 9c: n = 3
Ph
O
ICH2CO2Et
h
+
6
R =
OEt
overnight
N
Me
10
Entry
9
9:ICH2CO2Et
Yield (%)
Entry
15
Yielda (%)
10
6
13
14
1
2
3
4
5
6
a
9a
9a
9b
9b
9c
9c
2:1
3:1
1:1
2:1
1:1
2:1
52
73
2
0
1
2
3
RInCl2 15a
R2InCl 15b
R3In 15c
15
6
30
66
38
31
11b
Complex mixture
Complex mixture
Complex mixture
0
a
Based on R.
Alkynylindium compounds and ethyl iodoacetate were irradiated
overnight.
(Table 4, entry 1). The cyclization of 15b occurred efficiently
to give better yields (entry 2). Triarylindium 15c yielded 14
selectively in a modest yield (entry 3). These results clearly
b
E/Z¼22:78.
photo-induced intramolecular cyclizations of organoindium
compounds.
show that the photo-induced cleavage of Csp
by the irradiation.
2
eIn bond occurs
2.2.2. Allylindium
2.2.1. Arylindium
Diene 16a and indium were refluxed in THF for 3 h giv-
ing allylic indium A, which was then irradiated in THF to
afford the 5-exo-cyclization product 17 in 51% yield (Table
5, entry 1). The corresponding 6-endo-cyclization product
was not obtained. In order to estimate the amount of 17
formed via a pyrolytic course, the allylic indium compound
A was quenched with 1 M HCl prior to the irradiation, lead-
ing to the corresponding protonated product 18 in 11% yield
together with a small amount of 17 (3%) (entry 2). These re-
sults indicate that the present cyclization is induced by the
photolysis of A and the thermal decomposition is negligible.
Phenyllithium 12 was prepared from phenyl bromide 11
with t-BuLi at ꢀ78 ꢁC. When the solution of 12 was allowed
to warm to room temperature, the debrominated product 13
and the cyclization product 14 were obtained in low yields
(Scheme 1). The addition of InCl3 to 12 afforded a series of
phenylindium 15aec depending on the amount of InCl3. The
solution of 15b was heated under reflux conditions to give
13 quantitatively, showing that the transmetallation of 12 to
15 occurred completely and phenylindium 15b is thermally
stable even under the reflux conditions. Next, the photo-in-
duced reactions of 15aec were performed and the results
are shown in Table 4. The irradiation of 15a afforded the
5-exo product 14 in 30% yield along with 13 in 15% yield
Table 5
Intramolecular cyclization of allylindium compounds A and B
In2X3
X
Br
N
In
THF
h
or
11
Me
EtO2C
CO2Et
EtO2C
CO2Et
t-BuLi
n-C5H12/Et2O
–78 °C
A: X =Br
16a:X = Br
B: X = I
16b:X = I
Li
InCl (3-n)
n
InCl3/THF
–78 °C
+
+
N
Me
N
Me
EtO2C
CO2Et
EtO2C
CO2Et
EtO2C
CO2Et
12
2
15a: n=1
15b: n=2
15c: n=3
18
17
19
1. rt
2. H2O
1. rfx
2. H2O
Entry
16
Conditions
Products and yield (cis/trans)
Me
H
1
2
3
4
5a
a
16a
16a
16b
16b
16a
Reflux, 3 h/hn, rt, 36 h
Reflux, 4 h
17: 51% (85:15)
17: 3%, 18: 11%
13
100%
+
N
N
rt, 2 h/hn, rt, 24 h
rt, 2 h
17: 34% (93:7), 19: 24%
18: 18%, 19: 10%
17: 16% (57:43), 19: 61%
Me
Me
13
14
25%
30%
rt, 2 h/hn, rt, 20 h
With LiI.
Scheme 1.

T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
2645
The protonolysis of allylindium compounds generally pro-
I
I
Ph
ceeds selectively at the g-position to give the corresponding
protonated products in good yields.10 The low yield of the
protonolysis product 18 in entry 2 may be attributed to
the significant decompositionepolymerization of A under
the refluxing conditions. Therefore, the allylic indium com-
pound was next prepared at room temperature by changing
the bromide 16a to the more reactive iodide 16b. The disap-
pearance of metallic indium was observed by mixing 16b at
room temperature for 2 h, and the resulting solution was ir-
radiated for 24 h to produce 17 in 34% yield together with
the dimer 19 in 24% yield (entry 3). Quenching B by 1 M
HCl furnished the protonolysis product 18 in 18% yield
and the dimer 19 in 10% yield (entry 4). The reaction of
allylic indium derived from 16a in the presence of LiI at
room temperature gave rise to the dimer 19 predominantly
(61% yield) and 17 was obtained only in 16% yield (entry
5). These results suggest that allylindium compound B de-
rived from 16b has a tendency to undergo the dimerization,
which make it difficult to use B in the intramolecular
cyclization.
Next, similar dienes 20 and 23 were subjected to the
photochemical intramolecular cyclization reaction. The re-
sults are summarized in Table 6. Diene 20, in which a methyl
group was introduced at the reactive site, also gave the cor-
responding cyclization product 21 in moderate yield along
with the protonolysis product 22 (entry 1, Table 6). In the
case of tosyl amide 23, the 5-exo-cyclization product 24
was formed in 42% yield along with the dimer 25 in 19%
yield (entry 2). The allylic indium compound prepared with
InI in place of In gave 24 in 32% yield with a small amount
of the dehydrogenated product 26 (entry 3). The reactions of
dienes bearing a stylyl group 27 and linked by an ether bond
28 gave complicated mixtures and no cyclization product was
found.
O
28
EtO2C
CO2Et
27
The most plausible mechanism is depicted in Scheme 2; the
irradiation of A or B causes a homolytic cleavage of the IneC
bond and the resulting radical attacks the carbonecarbon double
bond intramolecularly in a 5-exo-trig fashion leading to the
cyclopentylmethyl radical, which abstracts hydrogen from the
solvent THF to produce 17. The presence of the radical interme-
diatewas confirmed by an experiment using 2,2,6,6-tetramethyl-
piperidin-1-oxyl (TEMPO):11 the photolysis of allylic indium A
in the presence of TEMPO gave adduct 29 in 17% yield.
h
A,B
EtO2C
CO2Et
EtO2C
CO2Et
CO2Et
N
O
H•
17
O•
N
EtO2C
EtO2C
CO2Et
29
TEMPO
Scheme 2. Possible mechanism for the photochemical radical cyclization.
3. Summary
The photochemical reactions of organoindium compounds
were found to generate the corresponding carbon-centered
radicals, which can be used for the radical reaction with the
intra- and intermolecular ways. Alkenyl- and alkynylindium
compounds underwent the intermolecular reactions with ethyl
a-iodoacetate to afford the corresponding b,g-unsaturated es-
ters. Similar to the success with the reactions of monoalkenyl-
and monoalkynylindium reagents initiated by Et3B, the use of
alkenyl- and alkynylindium dichlorides is essential for high
levels of yield in the photo-induced reactions. Aryl- and allyl-
indium reagents bearing a carbonecarbon double bond under-
went the intramolecular addition to give the corresponding
five-membered ring products. The present photochemical pro-
cess using organoindium compounds obviates the need for ad-
ditional reagents to initiate the reaction, but also provides an
alternative precursor to the radical reactions in place of
conventional organotin compounds.
Table 6
Photochemical reaction of allylic indium compounds derived from 20 and 23a
Entry
Substrate
t (h)
Product and yield (%)
Br
1
23
EtO2C
CO2Et
EtO2C
CO2Et
22: 6
EtO2C
CO2Et
21:33
20
I
N
2
20
22
Tos
N
N
24:42 (51:49)b
Tos
Tos
2
25: 19
23
4. Experimental section
3c
23
24:32 (63:37)b
N
Tos
26: 4
4.1. General
a
Allylindium compounds, prepared from diene 20 or 23 in THF at reflux,
were irradiated in THF (30 mL).
IR spectra were recorded on a JASCO IRA-102 spectropho-
tometer. 1H NMR spectra were obtained for solutions in
CDCl3 on a Varian Mercury 200 spectrometer (200 MHz) or
b
Diastereomeric ratio in the crude product.
InI was used instead of In.
c

2646
T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
a Varian Gemini 300 spectrometer (300 MHz) with Me4Si as
internal standard; J-values are given in hertz. 13C NMR spectra
were measured for solutions in CDCl3 with a Varian Gemini
200 spectrometer (50 MHz). Mass spectra were measured on
a Hitachi M-2000 spectrometer at 70 eV. Elemental analyses
were done with PerkineElmer 2400II. For photochemical re-
actions, a Riko Kagaku Sangyo UVL-100HA apparatus was
used. Photolyses were carried out under an argon atmosphere
using a 100 W high-pressure mercury lamp with a Pyrex filter.
Indium powder (99.99%) was obtained from Aldrich and use
as received. InCl3 (99.999%) was purchased from Aldrich
and dried by heating with a heat gun in vacuo before use.
THF and ether were dried with LiAlH4 before use.
room temperature overnight. The reaction was quenched
with water (5 mL). The products were extracted with ether,
washed with water and brine, and dried over Na2SO4. The sol-
vent was removed under reduced pressure to give a crude
product (142 mg), which was purified by chromatography on
silica gel (hexaneeAcOEt¼80:1 to AcOEt) to afford ethyl
4-phenyl-3-butenoate7f (6) (106 mg, 56%, E/Z¼86:14).
4.2.4. Photochemical reaction of (Z)-styrylindium (Table 1,
entry 4)
b-Bromostyrene15 (E/Z¼8:92, 183 mg, 1.0 mmol) used in
place of b-bromostyrene (E/Z¼82:18) gave a crude product
(151 mg), which was purified by chromatography on silica
gel (hexaneeAcOEt¼80:1 to AcOEt) to give 6 (79 mg,
83%, E/Z¼56:44).
4.2. Intermolecular reaction
4.2.1. Photochemical reaction of cinnamylindium
sesquibromide (Eq. 1)
4.2.5. Photochemical reaction of styrylindium 5b (Table 1,
entry 6)
A mixture of powdered metallic indium (0.26 g, 2.3 mmol)
and cinnamyl bromide (0.33 mL, 2.3 mmol) in THF (2 mL)
was refluxed for 2 h. The resulting cinnamyl sesquibromide
was diluted by THF (80 mL) and irradiated for 24 h. The reac-
tion was quenched with water (2 mL) and the solvent was
removed under reduced pressure. The product was extracted
with ether and the extracts were washed with water, and dried
over Na2SO4. The solvent was evaporated under reduced pres-
sure and the residue was purified by chromatography on silica
gel (elution with hexaneeCH2Cl2¼1:1) to give fractions con-
sisting of 3,6-diphenylhexa-1,5-diene12 (1) (37 mg, 15%),
a mixture of 1 and 3,4-diphenylhexa-1,5-diene12 (2) (24 mg,
10%, 1/2¼45:55), 2 (25 mg, 10%), and 5-phenylhept-6-en-
1,4-diol13 (3) (40 mg, 8%).
To a solution of b-bromostyrene (256 mL, 4.0 mmol) in
Et2O (2 mL), t-BuLi (n-pentane solution, 1.6 M, 5.0 mL,
8.0 mmol) was added at ꢀ78 ꢁC, and the reaction mixture
was kept for 1 h. The resulting styryllithium was treated
with a solution of InCl3 (442 mg, 2.0 mmol) in THF (5 mL)
at ꢀ78 ꢁC and the mixture was stirred for 1 h. The resulting
styrylindium was diluted with THF (1.5 mL) and irradiated
in the presence of ethyl iodoacetate (118 mL, 1.0 mmol) at
room temperature overnight. The reaction was quenched
with water (5 mL). The products were extracted with ether,
washed with water and brine, and dried over Na2SO4. The sol-
vent was removed under reduced pressure to give a crude
product (142 mg), which was purified by chromatography on
silica gel (hexaneeAcOEt¼80:1 to AcOEt) to afford (E)-6
(56 mg, 29%) and diethyl 2-styryl-1,4-butanedioate (7)
(26 mg, 19%, E/Z¼92:8).
4.2.2. Photochemical reaction of benzylindium sesquiiodide
(Eq. 2)
A
mixture of powdered metallic indium (92 mg,
4.2.5.1. Diethyl 2-styryl-1,4-butanedioate (7). 1H NMR
(200 MHz, CDCl3) d 1.24 (t, J¼6.1 Hz, 3H, CH3), 1.27 (t,
J¼8.0 Hz, 3H, CH3), 2.61 (dd, J¼6.1, 16.4 Hz, 1H, one of
CH2CO2), 2.94 (dd, J¼8.7, 16.4 Hz, 1H, the other of
CH2CO2), 3.65 (ddt, J¼0.8, 8.3, 10.3 Hz, 1H, CH), 4.05e
4.24 (m, 4H, CO2CH2CH3), 6.17 (dd, J¼8.3, 15.8 Hz, 1H,
]CH), 6.54 (d, J¼15.8 Hz, 1H, PhCH]), 7.10e7.40 (m,
5H, aromatic H); 13C NMR (50 MHz, CDCl3) d 14.4, 36.6,
45.1, 60.7, 61.1, 125.3, 126.2, 127.6, 128.3, 132.7, 136.2,
170.9, 172.3; IR (neat, cmꢀ1) 3349, 2981, 2872, 1950, 1881,
1732, 1599, 1463, 1159, 1095, 1028, 967, 859, 747, 649;
MS (EI) m/z 276 (Mþ); HRMS calcd for C16H20O4 (Mþ):
276.1362, found: 276.1381.
0.80 mmol) and benzyl iodide (0.17 g, 0.80 mmol) in DMF
(1 mL) was stirred at room temperature for 2 h. The resulting
benzylindium sesquiiodide was diluted with THF (80 mL) and
then irradiated for 20 h. The reaction was quenched with water
and the solvent was removed under reduced pressure. The
product was extracted with ether, washed with water, and dried
over Na2SO4. The solvent was evaporated under reduced pres-
sure and the residue was purified by chromatography on silica
gel (elution with hexane) to give 1,2-diphenylethane14 (4)
(47 mg, 64%).
4.2.3. Photochemical reaction of styrylindium 5a (Table 1,
entry 1)
To a solution of b-bromostyrene (128 mL, 1.0 mmol) in
Et2O (2 mL), t-BuLi (n-pentane solution, 1.6 mol/L,
1.25 mL, 2.0 mmol) was added at ꢀ78 ꢁC and the reaction
mixture was kept for 1 h. The reaction mixture was treated
with a solution of InCl3 (221 mg, 1.0 mmol) in THF (5 mL)
at ꢀ78 ꢁC and the mixture was stirred for 1 h. The resulting
styrylindium was diluted with THF (1.5 mL) and irradiated
in the presence of ethyl iodoacetate (118 mL, 1.0 mmol) at
4.2.6. Photochemical reaction of styrylindium 5a with
2-cyclohexenone (Table 2, entry 4)
To a solution of b-bromostyrene (256 mL, 4.0 mmol) in
Et2O (2 mL), t-BuLi (n-pentane solution, 1.6 M, 5.0 mL,
8.0 mmol) was added at ꢀ78 ꢁC, and the reaction mixture
was kept for 1 h. The resulting styryllithium was treated
with a solution of InCl3 (442 mg, 2.0 mmol) in THF (5 mL)
at ꢀ78 ꢁC and the mixture was stirred for 1 h. The resulting

T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
2647
styrylindium was diluted with CH3CN (10 mL) and irradiated
in the presence of 2-cyclohexenone (97 mL, 1.0 mmol) at room
temperature overnight. The reaction was quenched with 1 M
HCl (5 mL). The products were extracted with ether and
washed with water and brine, and dried over Na2SO4 to give
a crude product (320 mg), which was purified by chromatog-
raphy on silica gel (hexaneeAcOEt¼80:1 to AcOEt) to afford
816,17 (70 mg, 35%, E/Z¼37:63).
InCl3 (110 mg, 0.50 mmol) in THF (5 mL) was added and
the reaction mixture was kept for another 1 h at ꢀ78 ꢁC.
The mixture was diluted with THF (30 mL) and irradiated at
room temperature overnight. The reaction was quenched
with water and the solvent was removed under reduced pres-
sure. The residue was purified by chromatography on silica
gel (elution with hexane then AcOEt) to give a mixture of
N-allyl-N-methylaniline19 (13) and 2,3-dihyrdo-1,3-dimethy-
1
lindoline20 (14) (18 mg, 14: 5%, 13: 15% determined by H
4.2.7. Photochemical reaction of 2-phenylethynylindium 9a
with ethyl iodoacetate (Table 3, entry 1)
NMR) and 14 (15 mg, 25%).
To a solution of phenylacetylene (110 mL, 1.0 mmol) in
THF (2 mL), n-BuLi (n-hexane solution 1.6 M, 0.70 mL,
1.1 mmol) was added at ꢀ78 ꢁC and the reaction mixture
was stirred for 1 h. A solution of InCl3 (221 mg, 1.0 mmol)
in THF (5 mL) was added to the lithium acetylide at ꢀ78 ꢁC
and the mixture was kept for another 1 h. The resulting solu-
tion was diluted with THF (3 mL) and irradiated in the pres-
ence of ethyl iodoacetate (60 mL, 0.50 mmol) at room
temperature overnight. The reaction was quenched with water
(5 mL), and the products were extracted with ether. The or-
ganic layer was washed with water and brine, and dried over
Na2SO4. The solvent was removed under reduced pressure
giving a crude product (98 mg), which was purified by chro-
matography on silica gel (hexaneeAcOEt) to afford a mixture
of ethyl 4-phenyl-3-butenoate (6) and ethyl 4-phenyl-3-buty-
noate7g (10) (10 mg, 6: 2%, 10: 9% the ratio was determined
4.3.2. Synthesis of allylic bromide 16a
To a mixture of NaH (60% oil suspension, 0.48 g,
12 mmol) in THF (20 mL), diethyl allylmalonate (2.0 mL,
10 mmol) was added at 0 ꢁC and the mixture was stirred at
room temperature for 1 h. 1,4-Dibromobut-2-ene (3.2 g,
15 mmol) was added and refluxed for 3 h. The reaction was
quenched with water and the product was extracted with ether,
and the extracts were washed with water and dried over
Na2SO4. The solvent was removed under reduced pressure
and the residue was purified by column chromatography on
silica gel (elution with hexaneeEtOAc¼20:1) to give 16a
(1.6 g, 47%).
4.3.2.1. Diethyl 2-allyl-2-[4-bromo-2-butenyl]-1,3-propane-
dioate (16a). 1H NMR (200 MHz, CDCl3) d 1.25 (t,
J¼7.1 Hz, 6H, CH3), 2.64 (d, J¼6.5 Hz, 4H, CH2), 3.90 (d,
J¼7.1 Hz, 2H, CH2Br), 4.19 (q, J¼7.1 Hz, 4H, CH2CH3),
5.12 (d, J¼11 Hz, 1H, cis ]CH2), 5.13 (d, J¼15 Hz, 1H, trans
]CH2), 5.53e5.85 (m, 3H, CH]); 13C NMR (50 MHz,
CDCl3) d 14.8, 32.9, 35.6, 37.6, 57.7, 61.8, 119.7, 129.8,
130.8, 132.2, 170.5; IR (neat, cmꢀ1) 3030, 1740, 1450,
1380, 1290, 1210, 1160, 1100, 1040, 980, 930, 860. Anal.
Calcd for C14H21BrO4: C, 50.46; H, 6.35. Found: C, 50.45;
H, 6.62.
1
by H NMR) and 10 (40 mg, 43%).
4.2.8. Photochemical reaction of 2-phenylethynylindium 9b
(Table 3, entry 3)
To a solution of phenylacetylene (110 mL, 1.0 mmol) in
THF (2 mL), n-butyllithium (n-hexane, 1.6 M, 0.70 mL,
1.1 mmol) was added at ꢀ78 ꢁC and the mixture was kept
for 1 h at this temperature. A solution of InCl3 (110 mg,
0.50 mmol) in THF (5 mL) was added to the lithium acetylide
at ꢀ78 ꢁC and the mixture was kept for another 1 h at this tem-
perature. The resulting solution was diluted with THF (3 mL)
and irradiated in the presence of ethyl iodoacetate (60 mL,
0.50 mmol) at room temperature overnight. The reaction was
quenched with water (5 mL) and the products were extracted
with ether. The organic layer was washed with water and
brine, and dried over Na2SO4. The solvent was removed under
reduced pressure giving a crude product (108 mg), which was
purified by chromatography on silica gel (hexaneeAcOEt) to
afford a mixture of 6 and 10 (39 mg, 6: 11%, E/Z¼22:78 and
4.3.3. Synthesis of allylic iodide 16b
To a mixture of NaI (0.23 g, 1.5 mmol) in acetone (1 mL),
bromide 16a (0.33 g, 1.0 mmol) was added at room tempera-
ture and the mixture was stirred for 5 h. The reaction was
quenched with 1 M HCl and the product was extracted with
ether. The extracts were successively washed with aqueous
Na2SO3, water, and brine and dried over Na2SO4. The solvent
was removed under reduced pressure to give 16b (0.37 g,
96%).
1
10: 31%). The ratios were determined by H NMR.
4.3.3.1. Diethyl 2-allyl-2-[4-iodo-2-butenyl]-1,3-propane-
dioate (16b). 1H NMR (200 MHz, CDCl3) d 1.26 (t,
J¼7.2 Hz, 6H, CH3), 2.59e2.65 (m, 4H, CH2), 3.83 (d,
J¼7.8 Hz, 2H, CH2I), 4.20 (q, J¼7.2 Hz, H, CH2CH3), 5.11
(d, J¼11 Hz, 1H, cis ]CH2), 5.13 (d, J¼17 Hz, 1H, trans
]CH2), 5.48e5.89 (m, 3H, CH]); 13C NMR (50 MHz,
CDCl3) d 5.4, 14.3, 35.1, 37.1, 57.3, 61.4, 119.2, 127.9,
131.8, 131.9, 170.1; IR (neat, cmꢀ1) 3050, 3000, 1730,
1640, 1440, 1390, 1370, 1280, 1250, 1210, 1150, 1110,
1060, 1030, 970, 920, 860. Anal. Calcd for C14H21IO4: C,
44.22; H, 5.57. Found: C, 44.30; H, 5.78.
4.3. Intramolecular reaction
4.3.1. Photochemical reaction of dichloroindioaniline 15a
(Table 4, entry 1)
t-BuLi (n-pentane solution, 1.6 mol/L, 0.70 mL, 1.1 mmol)
was added to a solution of 2-bromo-N-allyl-N-methylaniline18
(11) (113 mg, 0.50 mmol) in n-pentaneeether (v/v¼9:1,
1.5 mL) at ꢀ78 ꢁC and the mixture was stirred for 1 h at
this temperature. To the resulting mixture, a solution of

2648
T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
4.3.4. Photochemical reaction of allylic indium compound
derived from 16a (Table 5, entry 1)
4.3.6.1. Tetraethyl 1,6,10,15-hexadecatetraene-4,4,13,13-tet-
racarboxylate (19). 1H NMR (300 MHz, CDCl3) d 1.25 (t, J¼
7.2 Hz, 12H, CH3), 1.92e2.10 (m, 4H,), 2.57e2.66 (m, 6H),
4.19 (q, J¼7.2 Hz, 8H, CH2CH3), 4.95e5.72 (m, 10H,
CH]CH2); 13C NMR (50 MHz, CDCl3) d 14.2, 32.5, 35.4,
36.6, 57.3, 61.0, 118.6, 123.6, 132.1, 134.1, 170.3; IR (neat,
cmꢀ1) 3000, 2950, 1730, 1640, 1440, 1360, 1280, 1210,
1140, 1100, 1040, 970, 920, 860, 800. Anal. Calcd for
C28H42O8: C, 66.38; H, 8.36. Found: C, 66.48; H, 8.62.
A
mixture of powdered metallic indium (46 mg,
0.40 mmol) and 8-bromo-4,4-diethoxycarbonyloct-1,6-diene
(16a) (0.20 g, 0.60 mmol) in THF (4 mL) was refluxed for
3 h. The resulting allylic indium reagent was diluted with
THF (90 mL) and then irradiated for 36 h. The reaction was
quenched with 1 M HCl and the solvent was removed under
reduced pressure. The product was extracted with ether and
washed with water, and dried over Na2SO4. The solvent was
evaporated under reduced pressure and the residue was puri-
fied by chromatography on silica gel (elution with hexanee
EtOAc¼20:1) to give 17 (77 mg, 51%, cis/trans¼85:15).
The cis/trans ratio was determined by the comparison with
the reported data of 1-methyl-2-vinylcyclopentane:21 d 0.86
(d, J¼7.2 Hz, 3H, Me, cis) and 0.99 (d, J¼5.9 Hz, 3H, Me,
trans), and dimethyl 3-methyl-4-vinylcyclopentane-1,1-di-
carboxylate:21 d 0.87 (d, J¼7.0 Hz, 3H, Me, cis) and 0.98
(d, J¼6.3 Hz, 3H, Me, trans).
4.3.7. Reaction of the allylic indium compound derived from
16b (Table 5, entry 4)
A
mixture of powdered metallic indium (52 mg,
0.45 mmol) and 16b (0.17 mg, 0.45 mmol) in THF (2 mL)
was stirred at room temperature for 2 h. The reaction was
quenched with water (5 mL) and the solvent was removed un-
der reduced pressure. The reaction was quenched with 1 M
HCl and the solvent was removed under reduced pressure.
The product was extracted with ether and washed with water,
and dried over Na2SO4. The solvent was evaporated under re-
duced pressure and the residue was purified by chromatogra-
phy on silica gel (elution with hexaneeEtOAc¼40:1) to give
18 (21 mg, 18%) and dimer 19 (11 mg, 10%).
4.3.4.1. Diethyl 3-methyl-4-vinyl-1,1-cyclopentanedicarboxy-
late22 (17). 1H NMR (200 MHz, CDCl3)
d 0.86 (d,
J¼6.9 Hz, 3H, cis CH3), 0.97 (d, J¼6.1 Hz, 3H, trans CH3),
1.25 (t, J¼7.1 Hz, 6H, CH3), 1.90e2.75 (m, 6H), 4.19 (q,
J¼7.1 Hz, 4H, CH2CH3), 4.98e5.05 (m, 2H, ]CH2), 5.75
(ddd, J¼18, 9.6, 8.2 Hz, 1H, CH]); IR (neat, cmꢀ1) 3100,
3000, 1730, 1640, 1460, 1440, 1380, 1365, 1290, 1250,
1180, 1145, 1100, 1050, 1030, 1000, 920, 860.
4.3.8. Photochemical reaction of allylic indium compound
derived from 16a in the presence of LiI (Table 5, entry 5)
A
mixture of powdered metallic indium (35 mg,
0.30 mmol), LiI (60 mg, 0.45 mmol), and 16a (0.15 g,
0.45 mmol) in THF (2 mL) was refluxed for 2 h. The resulting
allylic indium reagent was diluted with THF (50 mL) and irra-
diated for 20 h. The reaction was quenched with 1 M HCl
(4 mL) and the solvent was removed under reduced pressure.
The product was extracted with ether and washed with water,
and dried over Na2SO4. The solvent was evaporated under re-
duced pressure and the residue was purified by chromatogra-
phy on silica gel (elution with hexaneeEtOAc¼40:1) to give
17 (18 mg, 16%, cis/trans¼57:43) and dimer 19 (70 mg, 61%).
4.3.5. Reaction of the allylic indium compound derived from
16a (Table 5, entry 2)
A
mixture of powdered metallic indium (23 mg,
0.20 mmol) and 16a (0.10 g, 0.30 mmol) in THF (2 mL) was
refluxed for 4 h. The reaction was quenched with 1 M HCl
and the solvent was removed under reduced pressure. The
product was extracted with ether and washed with water,
and dried over Na2SO4. The solvent was evaporated under re-
duced pressure and the residue was purified by chromatogra-
phy on silica gel (elution with hexaneeEtOAc¼20:1) to give
a fraction consisting of 17 and diethyl 2-allyl-2-(3-butenyl)-
1,3-propanedioate23(18). The individual yield (17: 3%, 18:
11%) was determined on the basis of 1H NMR data (17/
18¼23:77).
4.3.9. Synthesis of diene 20
To a mixture of NaH (60% oil suspension, 0.20 g, 5 mmol)
in THF (10 mL), diethyl methallylmalonate (1.0 g, 4.7 mmol)
was added at 0 ꢁC and the mixture was stirred at room temper-
ature for 1 h. 1,4-Dibromobut-2-ene (2.0 g, 9.4 mmol) was
added and the mixture was refluxed overnight. The reaction
was quenched with 1 M HCl and the product was extracted
with ether, and the extracts were washed with water and dried
over Na2SO4. The solvent was removed under reduced pres-
sure and the residue was purified by column chromatography
on silica gel (elution with hexaneeEtOAc¼40:1) to give 20
(0.58 g, 35%).
4.3.6. Photochemical reaction of the allylic indium
compound derived from 16b (Table 5, entry 3)
A
mixture of powdered metallic indium (15 mg,
0.10 mmol) and 16b (76 mg, 0.20 mmol) in THF (1 mL)
was stirred at room temperature for 2 h. The resulting allylic
indium reagent was diluted with THF (30 mL), and the solu-
tion was irradiated for 22 h. The reaction was quenched with
water (10 mL), and the product was extracted with ether and
washed with water, and dried over Na2SO4. The solvent was
evaporated under reduced pressure and the residue was puri-
fied by chromatography on silica gel (elution with hexanee
EtOAc¼40:1) to give 17 (17 mg, 34%, cis/trans¼93:7) and
dimer 19 (25 mg, 24%).
4.3.9.1. Diethyl 2-(4-bromo-2-butenyl)-2-(2-methyl-2-pro-
penyl)-1,3-propanedioate (20). 1H NMR (200 MHz, CDCl3)
d 1.26 (t, J¼7.2 Hz, 6H, CH3), 1.66 (s, 3H, CH3), 2.66 (d,
J¼6.0 Hz, 2H, CH2), 2.70 (s, 2H, CH2), 3.90 (d, J¼6.6 Hz,
2H, CH2Br), 4.19 (q, J¼7.2 Hz, 4H, CH2CH3), 4.76 (s, 1H,
CH2]), 4.88 (s, 1H, CH2]), 5.57e5.84 (m, 2H, CH]); IR

T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
2649
(neat, cmꢀ1) 3475, 3100, 3000, 1730, 1640, 1440, 1360, 1270,
1240, 1200, 1150, 1090, 1060, 1030, 970, 900, 860, 730. Anal.
Calcd for C15H23BrO4:C, 51.88;H, 6.68. Found:C, 52.04; H, 6.56.
CH2Br), 5.11e5.20 (m, 2H, CH2]), 5.50e5.86 (m, 3H,
CH]), 7.26e7.32 (m, 2H, Ph), 7.66e7.71 (m, 2H, Ph);
13C NMR (50 MHz, CDCl3) 21.7, 31.6, 47.8, 49.8, 119.2,
126.9, 129.4, 129.5, 130.2, 132.2, 136.8, 143.1; IR (neat,
cmꢀ1) 2950, 1640, 1600, 1490, 1440, 1340, 1300, 1290,
1250, 1210, 1160, 1100, 1040, 970, 940, 910, 820, 760,
710, 660.
4.3.10. Photochemical reaction of allylic indium compound
derived from 20 (Table 6, entry 1)
A mixture of powdered metallic indium (35 mg, 0.30 mmol)
and diene 20 (0.16 g, 0.45 mmol) in THF (2 mL) was refluxed
for 2 h. The resulting allylic indium reagent was diluted with
THF (30 mL) and then irradiated for 23 h. The reaction was
quenched with 1 M HCl and the solvent was removed under
reduced pressure. The product was extracted with ether and
washed with water, and dried over Na2SO4. The solvent was
evaporated under reduced pressure and the residue was purified
by chromatography on silica gel (elution with hexanee
EtOAc¼20:1) to give a mixture of 21 and 22 (47 mg). The
4.3.11.2. N-Allyl-N-(4-iodo-2-butenyl)-4-methylbenzenesulfon-
amide (23). 1H NMR (200 MHz, CDCl3) d 2.43 (s, 3H,
CH3), 3.77e3.89 (m, 6H, CH2), 5.15 (d, J¼11 Hz, 1H, cis
CH2]), 5.17 (d, J¼17 Hz, 1H, trans CH2]), 5.42e5.89 (m,
3H, CH]), 7.26e7.32 (m, 2H, Ph), 7.66e7.71 (m, 2H, Ph);
IR (neat, cmꢀ1) 2950, 1640, 1600, 1500, 1440, 1340, 1300,
1290, 1250, 1150, 1120, 1090, 1020, 960, 930, 910, 820,
750, 700, 640. Anal. Calcd for C14H18INO2S: C, 42.98; H,
4.64; N, 3.58. Found: C, 43.37; H, 4.78; N, 3.51.
1
yields (21: 33%, 22: 6%) were determined by H NMR.
4.3.10.1. Diethyl 3,3-dimethyl-4-vinylcyclopentane-1,1-dicar-
boxylate (21). 1H NMR (200 MHz, CDCl3) d 0.78 (s, 3H,
CH3), 1.01 (s, 3H, CH3), 1.25 (t, J¼7.2 Hz, 6H, CH3),
2.17e2.43 (m, 5H), 4.18 (q, J¼7.2 Hz, 4H, CH2), 4.98e5.08
(m, 2H, ]CH2), 5.60e5.78 (m, 1H, ]CH). Anal. Calcd for
C15H24O4: C, 67.14; H, 9.01. Found: C, 66.81; H, 8.63.
4.3.12. Photochemical reaction of allylic indium compound
derived from 23 (Table 6, entry 2)
A
mixture of powdered metallic indium (31 mg,
0.27 mmol) and diene 23 (0.16 g, 0.40 mmol) in THF
(1 mL) was stirred at room temperature for 2 h. The resulting
allylic indium reagent was diluted with THF (30 mL) and then
irradiated for 20 h. The reaction was quenched with 1 M HCl
and the solvent was removed under reduced pressure. The
product was extracted with ether and washed with water,
and dried over Na2SO4. The solvent was evaporated under
reduced pressure and the residue was purified by chromatogra-
phy on silica gel (elution with hexaneeEtOAc¼20:1) to give
3-methyl-4-vinyl-1-(4-methylbenzenesulfonyl)pyrrolidine26
(24) (45 mg, d.r.¼55:45) and dimer 25 (20 mg, 19%).
4.3.10.2. Diethyl 2-(3-butenyl)-2-(2-methyl-2-propenyl)-1,3-
propanedioate24 (22). 1H NMR (200 MHz, CDCl3) d 1.26 (t,
J¼7.2 Hz, 6H, CH3), 1.95e1.99 (m, 4H, CH2), 2.73 (s, 3H,
CH3), 4.18 (q, J¼7.2 Hz, 4H, CH2), 4.74 (s, 1H, CH2]),
4.86 (s, 1H CH2]), 4.95 (d, J¼9.2 Hz, 1H, cis CH2]),
5.02 (d, J¼19 Hz, 1H, trans CH2]), 5.69e5.90 (m, 1H,
]CH); IR (neat, cmꢀ1) 3100, 3000, 1730, 1640, 1440,
1360, 1300, 1260, 1240, 1200, 1180, 1100, 1030, 910, 860.
4.3.12.1. 3-Methyl-4-vinyl-1-(4-methylbenzenesulfonyl)pyrrol-
idine26 (24). 1H NMR (200 MHz, CDCl3) d 0.76 (d,
J¼6.8 Hz, 3H, cis or trans CH3), 0.90 (d, J¼6.6 Hz, 3H, trans
or cis CH3), 2.14e2.27 (m, 1H), 2.59e2.72 (m, 1H), 2.96 (dd,
J¼9.8, 6.0 Hz, 1H, CH), 3.18 (dd, J¼9.8, 6.0 Hz, 1H, CH),
3.36e3.60 (m, 2H), 4.97 (d, J¼10 Hz, 1H, cis CH2]), 4.98
(d, J¼17 Hz, 1H, trans CH2]), 5.49 (ddd, J¼17, 10,
8.2 Hz, 1H, CH]), 7.33 (m, 2H, Ph), 7.72 (m, 2H, Ph); IR
(neat, cmꢀ1) 3050, 2950, 2900, 2850, 1640, 1590, 1490,
1470, 1450, 1420, 1380, 1340, 1300, 1280, 1160, 1090,
1040, 1010, 910, 810, 800, 730, 700, 650.
4.3.11. Synthesis of diene 23
To a mixture of NaH (60% oil suspension, 0.26 g,
6.5 mmol) in DMF (50 mL), N-allyl-4-methylbenzenesulfona-
mide25 (2.0 g, 10 mmol) was added at room temperature and
stirred for 2 h. 1,4-Dibromobut-2-ene (6.4 g, 30 mmol) was
added and the reaction mixture was stirred at room tempera-
ture for 23 h. The reaction was quenched with 1 M HCl and
the product was extracted with ether, and the extracts were
washed with water and dried over Na2SO4. The solvent was
removed under reduced pressure and the residue was purified
by column chromatography on silica gel (elution with hexanee
EtOAc¼40:1) to give N-allyl-N-(4-bromo-2-butenyl)-4-meth-
ylbenzenesulfonamide (0.90 g, 27%). This bromide (0.89 g,
2.7 mmol) was treated with NaI (0.81 g, 5.4 mmol) in acetone
(10 mL) at room temperature for 3 h. The product was ex-
tracted with ether and washed with brine, and dried over
Na2SO4. The solvent was removed under reduced pressure
to give N-allyl-N-(4-iodo-2-butenyl)-4-methylbenzenesulfona-
mide (23) (0.86 g, 82%).
4.3.12.2. Dimer 25. 1H NMR (200 MHz, CDCl3) d 1.96e2.04
(m, 1H, CH), 2.42 (s, 3H, CH3), 3.70e3.79 (m, 4H, CH2),
4.92e5.69 (m, 5H), 7.26e7.32 (m, 2H, Ph), 7.69e7.75 (m,
2H, Ph); 13C NMR (50 MHz, CDCl3) d 22.1, 32.1, 49.1,
49.6, 119.0, 125.0, 127.4, 129.8, 133.0, 134.8, 137.6, 143.3.
4.3.12.3. 3-Methylene-4-vinyl-1-(4-methylbenzenesulfonyl)pyr-
rolidine27 (26). 1H NMR (200 MHz, CDCl3) d 2.44 (s, 3H,
CH3), 2.75e2.90 (m, 1H), 3.13e3.35 (m, 1H), 3.49e3.78
(m, 2H), 3.94e4.13 (m, 1H), 4.83e5.14 (m, 4H, CH2]),
5.40e5.59 (m, 1H, CH]), 7.29e7.38 (m, 2H, Ph), 7.65e
7.78 (m, 2H, Ph).
4.3.11.1. N-Allyl-N-(4-bromo-2-butenyl)-4-methylbenzenesul-
fonamide. 1H NMR (200 MHz, CDCl3) d 2.43 (s, 3H, CH3),
3.80 (d, J¼6.2 Hz, 4H, CH2N), 3.87 (d, J¼7.4 Hz, 2H,

2650
T. Hirashita et al. / Tetrahedron 64 (2008) 2642e2650
4. (a) Araki, S.; Nakano, H.; Subburaj, K.; Hirashita, T.; Shibutani, K.; Yama-
mura, H.; Kawai, M.; Butsugan, Y. Tetrahedron Lett. 1998, 39, 6327e6330;
(b) Araki, S.; Shiraki, F.; Tanaka, T.; Nakano, H.; Subburaj, K.; Hirashita, T.;
Yamamura, H.; Kawai, M. Chem.dEur. J. 2001, 7, 2784e2790.
5. Araki, S.; Horie, T.; Kato, M.; Hirashita, T.; Yamamura, H.; Kawai, M.
Tetrahedron Lett. 1999, 40, 2331e2334.
4.3.13. Photochemical reaction of allylindium A in the
presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (Scheme 2)
A mixture of powdered indium (35 mg, 0.30 mmol) and
16a (0.15 g, 0.45 mmol) in THF (2 mL) was refluxed for
2 h. The resulting allylic indium reagent was diluted with
THF (80 mL) and 2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO) (0.14 g, 0.90 mmol) was added. The solution was
irradiated at room temperature for 22 h. The reaction was
quenched with water (5 mL) and the solvent was removed un-
der reduced pressure. The product was extracted with ether
and washed with water, and dried over Na2SO4. The solvent
was evaporated under reduced pressure and the residue was
purified by chromatography on silica gel (elution with hexa-
neeEtOAc¼80:1) to give 29 (31 mg, 17%).
6. Araki, S.; Kamei, T.; Igarashi, Y.; Hirashita, T.; Yamamura, H.; Kawai, M.
Tetrahedron Lett. 1999, 40, 7999e8002.
7. (a) Miyabe, H.; Naito, T. Org. Biomol. Chem. 2004, 2, 1267e1270; (b)
Miyabe, H.; Ueda, M.; Nishimura, A.; Naito, T. Tetrahedron 2004, 60,
4227e4235; (c) Yanada, R.; Koh, Y.; Nishimori, N.; Matsumura, A.;
Obika, S.; Mitsuya, H.; Fujii, N.; Takemoto, Y. J. Org. Chem. 2004, 69,
2417e2422; (d) Yanada, R.; Obika, S.; Nishimori, N.; Yamauchi, M.;
Takemoto, Y. Tetrahedron Lett. 2004, 45, 2331e2334; (e) Takami, K.;
Mikami, S.; Yorimitsu, H.; Shinokubo, H.; Oshima, K. Tetrahedron
2003, 59, 6627e6635; (f) Takami, K.; Yorimitsu, H.; Oshima, K.
Org. Lett. 2004, 6, 4555e4558; (g) Takami, K.; Usugi, S.; Yorimitsu,
H.; Oshima, K. Synthesis 2005, 824e839.
8. Yamaji, M.; Hama, Y.; Arai, S.; Hoshino, M. Inorg. Chem. 1987, 26,
4375e4378.
4.3.13.1. Diethyl 3-[[(2,2,6,6-tetramethyl-1-piperidinyl)oxy]-
methyl] 4-vinyl-1,1-cyclopentanedicarboxylate (29). 1H NMR
(200 MHz, CDCl3) d 1.05e1.10 (m, 12H, CH3), 1.25 (t,
J¼7.2 Hz, 6H, CH3), 1.35e1.60 (m, 6H, CH2), 2.11e2.21
(m, 2H), 2.27e2.55 (m, 3H), 2.71e2.85 (m, 1H), 3.52e3.98
(m, 2H, OCH2), 4.19 and 4.20 (each q, J¼7.1 Hz, total 4H,
CH2CH3), 4.95e5.07 (m, 2H, ]CH2), 5.79 (ddd, J¼17.0,
10.1, 8.3 Hz, 1H, CH]); 13C NMR (50 MHz, CDCl3)
d 14.0, 17.1, 20.0, 33.0, 36.8, 39.0, 39.6, 42.0, 45.1, 59.2,
59.7, 61.3, 115.3, 138.1, 172.4, 172.7; IR (neat, cmꢀ1) 2980,
2940, 1730, 1450, 1360, 1300, 1250, 1180, 1130, 1100,
1040, 1000, 910, 860, 800, 710. Anal. Calcd for
C23H39NO5: C, 67.45; H, 9.60; N, 3.42. Found: C, 67.42; H,
9.68; N, 3.30.
9. Preliminary communication: Hirashita, T.; Tanaka, J.; Hayashi, A.; Araki,
S. Tetrahedron Lett. 2005, 46, 289e292.
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1991, 56, 2538e2542.
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Nishino, T.; Watanabe, T.; Okada, M.; Nishiyama, Y.; Sonoda, N.
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¨
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¨
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¨