Radical coupling of iodocarbonyl compounds with butenylindium generated by Transmetalation between cyclopropylmethylstannane and indium halides

Article abstract of DOI:10.1021/om8009156

The reaction of cyclopropylmethylstannane 1 with α-iodocarbonyl compounds 2 in the presence of either InBr₃ or InCl₃ gave the C-C coupling products 3. Various types of iodocarbonyl compounds such as esters, amides, and ketones were a

Full text of DOI:10.1021/om8009156

132
Organometallics 2009, 28, 132–139
Radical Coupling of Iodocarbonyl Compounds with Butenylindium
Generated by Transmetalation between Cyclopropylmethylstannane
and Indium Halides
Makoto Yasuda, Kensuke Kiyokawa, Kenji Osaki, and Akio Baba*
Department of Applied Chemistry, Center for Atomic and Molecular Technologies, Graduate School of
Engineering, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
ReceiVed September 19, 2008
The reaction of cyclopropylmethylstannane 1 with R-iodocarbonyl compounds 2 in the presence of
either InBr3 or InCl3 gave the C-C coupling products 3. Various types of iodocarbonyl compounds such
as esters, amides, and ketones were applied to this system to afford the corresponding cyclopropylethyl-
substituted carbonyls 3. Transmetalation between cyclopropylmethylstannane and indium halides afforded
butenylindium dihalide and dibutenylindium halide, as confirmed by NMR spectroscopy. The reactivity
of dibutenylindium halide was greater than that of monobutenyl species. The active species, dibutenylin-
dium halide, was stabilized by complexation using DPPE, and its structure was analyzed using X-ray
crystallography. The solid state of the complex shows a linear structure with a core (-Cl-In-
Cl–In–P-C-C-P-In-)n with five-coordinated indium centers. The reaction between 1 and 2, mediated
by indium halides, proceeded in a radical manner. The in situ-generated alkylindium species and a small
amount of oxygen, which can be supplied by atmospheric air, initiated the radical reaction.
was required. Effective transmetalation between the stannane
and indium halides gives the butenylindium species, as con-
firmed by NMR spectroscopy and X-ray analysis. The use of
the stannane is advantageous because it allows smooth and clean
transmetalation, and the byproduct, halostannane, had no effect
on the reaction system.
Introduction
Cyclopropylmethylstannane has the potential to introduce a
cyclopropyl ring to organic molecules through C-C bond
formation. Although some examples using cyclopropylmethyl-
stannane were reported by Young, only ring-opening reactions
took place with inorganic reagents such as SO2, Brønstead acid,
or iodine.1 The lack of a suitable activation method creates
difficulty in the control of cyclopropylmethylstannane for
carbon-carbon bond formation. There are some examples of
starting from a butenylmetal species instead of a cyclopropyl-
methyl compound to introduce cyclopropylmethyl groups in
organic compounds. For example, there is the reaction of
butenylstannane with acetals, acid chlorides, and aldehydes in
the presence of Lewis acids to form cyclopropylmethylated
products.2,3 In situ-generated butenylgallium, -indium, and
-aluminum from butenyl Grignard reagents with metal halides
are assumed, and they couple with R-halocarbonyls in the
presence of Et3B as a radical initiator.4 However, the reaction
using cyclopropylmethylstannane for introduction of the cyclo-
propyl ring through C-C bond formation has never been
reported as far as we know.
Results and Discussion
Reaction of Cyclopropymethylstannane 1 with r-Iodocar-
bonyl 2a. The reaction of cyclopropylmethylstannane 1 with
phenyl 2-iodoacetate 2a in the presence of 0.5 equiv of InBr3
gave the corresponding coupling product 3a in 73% yield in
toluene and a nitrogen-flowing flask (Table 1, entry 1). Although
a trace amount of the ring-opening product, which was not
precisely identified,5 was observed, the effective introduction
of a cyclopropyl group was accomplished. Without additives,
there was no reaction (entry 2). Some solvents, such as Et2O or
MeCN, gave lower yields, and no reaction was observed in THF,
probably due to strong solvent coordination (entries 4-6).
Exposure to air improved the yield of 3a (entry 7). The other
indium halides, InCl3 or InI3, gave lower yields (entries 8 and
9). GaCl3 also gave a high yield of 3a (entry 10), but AlCl3
afforded phenyl 4-iodohexanoate in 41% yield with a trace
amount of 3a (entry 11). In the reaction using BF3 · OEt2 as an
additive, a low yield of 3a was obtained and the rearranged
species, butenylstannane, was confirmed after the reaction (entry
12).1 When ZnCl2, TiCl4, ZrCl4, HfCl4, or SnCl2 was used as
additive, satisfactory yields were not obtained (entries 13-17).
The loading of a catalytic amount of galvinoxyl suppressed the
reaction (entry 18), and thus the reaction proceeds via a radical
mechanism.
In this paper, we report a radical coupling of cyclopropyl-
methylstannane with R-halocarbonyl compounds mediated by
indium halides. In this system, no additional radical initiator
* Corresponding author. E-mail: baba@chem.eng.osaka-u.ac.jp.
(1) (a) Lucke, A. J.; Young, D. J. J. Org. Chem. 2005, 70, 3579–3583.
(b) Lucke, A. J.; Young, D. J. Tetrahedron Lett. 1991, 32, 807–810.
(2) (a) Sugawara, M.; Yoshida, J. Chem. Commun. 1999, 505–506. (b)
Sugawara, M.; Yoshida, J. Tetrahedron 2000, 56, 4683–4689.
(3) (a) Peterson, D. J.; Robbins, D. Tetrahedron Lett. 1972, 13, 2135–
2138. (b) Peterson, D. J.; Robbins, D.; Hansen, J. R. J. Organomet. Chem.
1974, 73, 237–250. (c) Herndon, J. W.; Harp, J. J. Tetrahedron Lett. 1992,
33, 6243–6246. (d) Ueno, Y.; Ohta, M.; Okawara, M. Tetrahedron Lett.
1982, 23, 2577–2580. (e) Nicolaou, K. C.; Claremon, D. A.; Barnette, W. E.;
Seitz, S. P. J. Am. Chem. Soc. 1979, 101, 3704–3706.
Investigation of Active Species. To gain a thorough under-
standing of the active species, the relationship between the
(5) (a) Sakurai, H.; Inai, T.; Hosomi, A. Tetrahedron Lett. 1977, 18,
4045–4048. (b) Hatanaka, Y.; Kuwajima, I. Tetrahedron Lett. 1986, 27,
719–722.
(4) Usugi, S.-i.; Tsuritani, T.; Yorimitsu, H.; Shinokubo, H.; Oshima,
K. Bull. Chem. Soc. Jpn. 2002, 75, 841–845.
10.1021/om8009156 CCC: $40.75
2009 American Chemical Society
Publication on Web 12/02/2008

Radical Coupling of Iodocarbonyl Compounds
Organometallics, Vol. 28, No. 1, 2009 133
Table 1. Optimization of Reaction Conditionsa
entry
additive
solvent
yield, %
1
2
3
4
InBr3
none
toluene
toluene
CH2Cl2
Et2O
MeCN
THF
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
73
0
76
42
17
0
79
50
57
71
<5c
9
0
13
0
0
0
InBr3
InBr3
InBr3
InBr3
InBr3
InCl3
Inl3
5
6
7b
8
9
10
11
12
13
14
15
16
17
18
GaCl3
AlCl3
BF3 · OEt2
ZnCl2
TiCl4
ZrCl4
HfCl4
SnCl2
d
InBr3
<5
a All entries were carried out at room temperature in solvent (1 mL)
with 1.0 mmol of 1, 1.0 mmol of 2a, and 0.5 mmol of additive.
b Exposure to air (15 min). c Phenyl 4-iodohexanoate was formed (41%
yield). d Addition of galvinoxyl (0.1 mmol).
Figure 2. 1H NMR spectra of the reaction mixtures of InBr3 and 1
with (a) 1/1, (b) 1/2, and (c) 1/3 ratios in toluene-d8.
observed (spectrum c). The mass spectrum of the 1/2 mixture
of InBr3/1 gave the molecular ion corresponding to the dibute-
nylindium species [calculated for (C8H14In), 225.0134; found
for m/z, 225.0134]. The dibutenyl species 5 was more reactive
than 4, as evidenced by more rapid consumption of 5 than of 4
when iodoester 2a was added to a mixture that included both 4
and 5 (see Supporting Information). The amount of 4 remained
nearly constant until 5 was completely consumed. Both butenyl
groups on 5 were transferred to the product prior to transfer of
the butenyl group on 4. The amount of the monobutenyl species
4 was decreased after 5 had disappeared (see Supporting
Information). The result that loading 1.0 equiv of InBr3 resulted
in low efficiency, as shown in Figure 1, is consistent with the
greater production of the less reactive monosubstituted indium
species. Transmetalation of allylic stannane or hydrostannane
with indium halides is widely reported,6,7 but this is the first
example where transmetalation of cyclopropylmethylstannane
results in a homoallylic building block.8
Figure 1. Relationship between amount of InBr3 and the yield of
3a in the reaction of 1 (1 mmol) with 2a (1 mmol) at rt for 4.5 h.
Reaction Mechanism. To investigate the effect of air on the
coupling reaction shown in Table 1, the InBr3-mediated reaction
of 1 with 2a was performed in a nitrogen-filled glovebox (O2
< 5 ppm), as shown in Scheme 1. The reaction gave 3a in 20%
yield after 4.5 h (19% yield even after 10 days). On the other
hand, loading 10 mL of air through a syringe into the mixture
of 1, 2a, and InBr3 prepared in the glovebox gave 3a in 81%
yield after stirring for 4.5 h. These results suggest that oxygen
plays an important role in the generation of radical species like
loading ratio of InBr3/1 and the product yield was investigated
in the reaction of 1 with 2a, and the results are shown in Figure
1. As the ratio InBr3/1 increased from 0.1 to 0.5, higher yields
of 3a were obtained, and ca. 0.5 equiv of InBr3 afforded the
highest yield. It was curious that ca. 0.3 equiv of InBr3 also
gave a relatively high yield, while the yield was reduced when
1.0 equiv of InBr3 was used. These results suggest generation
of different active species as a result of varying the ratio of
InBr3/1.
As confirmation of the conclusion demonstrated by the results
in Figure 1, we examined the three types of mixtures of InBr3
and 1 with the ratios of 1/1, 1/2, and 1/3 () InBr3/1) using
NMR spectroscopy (Figure 2). The 1/1 mixture of InBr3/1 gave
two types of butenyl-substituted species that were assumed to
be butenylindium dibromide 4 and dibutenylindium bromide 5
generated by transmetalation (spectrum a). One species that is
reasonable for dibutenylindium bromide 5 was observed when
mixed at a ratio of 1/2 (InBr3/1) (spectrum b). No other highly
substituted species were found from the 1/3 mixture (InBr3/1),
and only dibutenylindium species 5 and unreacted 1 were
(6) (a) Yasuda, M.; Miyai, T.; Shibata, I.; Baba, A.; Nomura, R.;
Matsuda, H. Tetrahedron Lett. 1995, 36, 9497–9500. (b) Miyai, T.; Inoue,
K.; Yasuda, M.; Baba, A. Synlett 1997, 699–700. (c) Inoue, K.; Shimizu,
Y.; Shibata, I.; Baba, A. Synlett 2001, 1659–1661. (d) Miyai, T.; Inoue,
K.; Yasuda, M.; Shibata, I.; Baba, A. Tetrahedron Lett. 1998, 39, 1929–
1932. (e) Inoue, K.; Yasuda, M.; Shibata, I.; Baba, A. Tetrahedron Lett.
2000, 41, 113–116. (f) Inoue, K.; Sawada, A.; Shibata, I.; Baba, A.
Tetrahedron Lett. 2001, 42, 4661–4663. (g) Baba, A.; Shibata, I. Chem.
Rec. 2005, 5, 323–335.
(7) Marshall, J. A.; Hinkle, K. W. J. Org. Chem. 1995, 60, 1920–1921.
(8) We examined the transmetalation of 1 with AlCl3 but observed only
butenylstannane as a rearranged product. GaCl3 gave butenylgallium species
in the reaction with 1, and further studies are now in progress.

134 Organometallics, Vol. 28, No. 1, 2009
Yasuda et al.
Scheme 1. Effect of Air on the Coupling Reaction
Scheme 2. Plausible Reaction Mechanism
Figure 3. ORTEP drawing of molecular structure of dibutenylin-
dium chloride-DPPE complex 9 (all hydrogens are omitted for
clarity).
Scheme 3. Isolation of Butenylindium Species
which abstracts iodine from 2, and the acylmethyl radical 6 is
regenerated. When the radical species 6 is trapped by dibute-
nylindium bromide 5, the resulting indium radical, butenylin-
dium(II) bromide 8′, is generated via 7′. The species 8′ abstracts
the iodine of 2 to give 6 and butenylbromoindium(III) iodide.
Because the formed butenylbromoindium(III) iodide is close
to radical 6, fast coupling between them takes place effectively.10
This mechanism is consistent with the observation that both
butenyl groups on dibutenylindium bromide 5 are preferentially
consumed over the butenyl group on 4. Species 7 could abstract
an iodine from 2 to afford an iodinated compound, which then
cyclizes into product 3.11 However, this mechanism does not
explain the rate difference between the butenyl groups on 5 and
4. Another interesting point is that the byproduct halostannane
is not likely to affect the reaction system, and transmetalation
starting from tin compounds is quite effective.
the O2-Et3B system.9 In our system, use of another radical
initiator is not necessary, as exposure to air is sufficient to initiate
the coupling reaction. The in situ-generated butenylindium
species acts as a radical initiator as well as an alkylating reagent.
The conventional experimental bench procedure (not in a
glovebox) using a nitrogen-flow system may have adequate
oxygen to accelerate the reaction system.
A plausible reaction mechanism is shown in Scheme 2.
Transmetalation between 1 and InBr3 gives butenylindium
species A (other butenyl group and/or ligands are omitted on
In). Oxygen-assisted radical initiation abstracts iodine from the
iodocarobonyl compound 2.9 The generated acylmethyl radical
6 is trapped by butenylindium to give the radical species 7.
Species 7 cyclizes with elimination of the indium radical 8,
X-ray Analysis of Butenylindium Generated by Trans-
metalation. Complexation of the active species in the reaction
system by various ligands was examined to prove that bute-
nylindium species were generated using X-ray analysis of
(9) (a) Nozaki, K.; Oshima, K.; Utimoto, K. J. Am. Chem. Soc. 1987,
109, 2547–2549. (b) Miura, K.; Ichinose, Y.; Nozaki, K.; Fugami, K.;
Oshima, K.; Utimoto, K. Bull. Chem. Soc. Jpn. 1989, 62, 143–147. (c)
Yorimitsu, H.; Nakamura, T.; Shinokubo, H.; Oshima, K.; Omoto, K.;
Fujimoto, H. J. Am. Chem. Soc. 2000, 122, 11041–11047. (d) Ollivier, C.;
Renaud, P. Chem. ReV. 2001, 101, 3415–3434. (e) Yorimitsu, H.; Oshima,
K. In Radicals in Organic Synthesis; Renaud, P.; Sibi, M. P. Eds.; Wiley-
VCH: Weinheim, 2001; Vol. 1, Chapter 1.2.
(10) It might also be explainable that the iodoindium species has a high
reactivity toward the carbonyl compound. The halogens on the indium center
dramatically affect the reactivity of oxy-functionalized compounds; for
example: Nishimoto, Y.; Yasuda, M.; Baba, A. Org. Lett. 2007, 9, 4931–
4934. The iodine might supply high reactivity in this case.
(11) A halogen substitution reaction using alkylindium species toward
haloalkenes was reported: Nomura, R.; Miyazaki, S.-i.; Matsuda, H. J. Am.
Chem. Soc. 1992, 114, 2738–2740.

Radical Coupling of Iodocarbonyl Compounds
Organometallics, Vol. 28, No. 1, 2009 135
Figure 4. Molecular structure and its intermolecular contacts of dibutenylindium chloride-DPPE complex 9 (all hydrogens are omitted for
clarity). Selected bond angles (deg) and lengths (Å): C(1)-In(1)-C(5) 146.6(3), C(1)-In(1)-Cleq(1) 106.5(3), C(5)-In(1)-Cleq(1) 105.93(17),
P(1)-In(1)-Clax(1) 169.95(2), P(1)-In(1)-Cleq(1) 88.73(3), In(1)-C(1) 2.145(11), In(1)-C(5) 2.148(6), In(1)-P(1) 2.9264(11), In(1)-Cleq(1)
2.5011(17), In(1)-Clax(1) 2.9899(13).
Figure 5. Packing structure of dibutenylindium chloride-DPPE
complex 9 (all hydrogens are omitted for clarity).
isolated compounds. Among various ligands and indium sources
employed, DPPE and InCl3 gave a crystal of dibutenylindium
complex 9 that was suitable for X-ray analysis, as shown in
Scheme 3.
The ORTEP drawing of the indium complex 9 and its
intermolecular contacts are shown in Figures 3 and 4. The five-
coordinated indium centers had two butenyl groups, a phos-
phorus in DPPE, and two chlorines. Each chlorine binds two
indium centers by bridging.12 Although DPPE is often used as
a bidentate ligand, each phosphine moiety in 9 independently
coordinates to different indium centers. The indium center
exhibited a distorted trigonal bipyramidal structure with bond
angles of C-In-C (146.6°) and C-In-Cl (106.5° and 105.9°),
the sum of which was 359°. P-In-Cl exhibited bond angles
of 169.95° and 88.73°. The lengths of the two In-C bonds were
2.145 and 2.148 Å. The lengths of the other three bonds around
the indium, In-P, In-Cleq, and In-Clax, were 2.926, 2.501,
and 2.990 Å, respectively. This is the first example of X-ray
crystallographic analysis of a butenylindium species.
Figure 6. Part of a linear shaped structure of dibutenylindium
chloride-DPPE complex 9 (In, P, and carbons of DPPE are shown
only for clarity). Views along the a axis and c axis (with a slight
deviation) are shown in (i) and (ii), respectively.
Cl-In-P-C-C-P-In-)n, as shown in Figures 5 and 6. The
unit has a length of ca. 10 Å. The view along the c axis of the
linear structure exhibits three types of atoms (P, In, Cl) in a
linear arrangement at close distances. This arrangement appears
promising for new materials, although applications of this
compound have not yet been investigated.
Synthesis of Cyclopropylethyl Carbonyl Compounds 3.
Table 2 shows the scope and limitations of using the reaction
system for various substrates. The reactions were carried out
with exposure to air through the CaCl2 drying tube. Primary
iodoesters 2a-d (entries 1-4) effectively gave the correspond-
ing coupling products, the cyclopropylethyl carbonyl compounds
3a-d. Although the tert-butyl ester 2e gave a low yield, in the
absence of air, the yield increased to 53% (entry 5).13 The
coupling also proceeded with secondary substrates 2f-h in
moderate to high yields (entries 6-8). A high yield was obtained
for the reaction with iodolactone 2i (entry 9). The reaction with
Because two In-Cl moieties interact with each other and the
phosphines in DPPE independently coordinate to indium centers,
the packing structure is clearly linear with a core (-Cl-In-
(12) (a) Schachner, J. A.; Lund, C. L.; Burgess, I. J.; Quail, J. W.;
Schatte, G.; Mu¨ller, J. Organometallics 2008, 27, 4703–4710. (b) Schachner,
J. A.; Lund, C. L.; Quail, J. W.; Mu¨ller, J. Organometallics 2005, 24, 4483–
4488.

136 Organometallics, Vol. 28, No. 1, 2009
Yasuda et al.
Table 2. Reaction of 1 with r-Iodocarbonyl Compounds 2a
require a radical initiator. Open air conditions sometimes
accelerated the radical reaction pathway. The generated dib-
utenylindium species was stabilized by a phosphine ligand, and
the resulting complex was analyzed using X-ray crystallography.
The butenylindium species was used as an alkylating reagent
without a radical initiator. Transmetalation starting from the
stannane proceeded in an effective and clean manner for the
synthesis of interesting cyclopropylated carbonyl compounds.
Experimental Section
General Procedures. IR spectra were recorded as thin films or
as solids in KBr pellets on a HORIBA FT-720 spectrophotometer.
1H and 13C NMR spectra were obtained with a 400 and 100 MHz
spectrometer, respectively, with TMS as internal standard. 119Sn
NMR spectra were obtained with a 150 MHz spectrometer with
Me4Sn as external standard. Mass spectra were recorded on a JEOL
JMS-DS303. All reactions were carried out under nitrogen. Column
chromatography was performed on silica gel (Merck C60). Recycle
GPC was performed with CHCl3 as the eluent. Bulb-to-bulb
distillation (Kugelrohr) was accomplished in a Sibata GTO-250RS
at the oven temperature and pressure indicated. Yields were
1
determined by GLC or H NMR using internal standards.
Materials. Dehydrated toluene, dichloromethane, Et2O, aceto-
nitrile, and THF were purchased and used as obtained. The additives
examined in Table 1 were also purchased from commercial sources.
Cyclopropylmethylstannane 1 was prepared as previously desc-
ribed.1a All iodocarobnyls 2a-l were prepared according to the
known method.14 The spectral data of 2d,15 2e,16 2g,17 2h,14 2i,18
2k,19 and 2l20 were in excellent agreement with the reported data.
The spectral data of 2c were in an excellent agreement with those
obtained for the commercially available product. The synthetic
procedure and spectral data of the other iodocarbonyls 2a, 2b, 2f,
and 2j are shown below. All other reagents were commercially
available.
Cyclopropylmethyltributylstannane (1).21 To tributyltin meth-
oxide (330 mmol) was added poly(methylhydrosiloxane) (330
mmol), and the mixture was stirred for 8 h at room temperature.
The resultant mixture was purified by distillation under reduced
pressure to give Bu3SnH (85.9 g, 89%).22 To hexachloroacetone
(600 mmol) was added triphenylphosphine (110 mmol) at 0 °C,
and the suspension was stirred vigorously for 5 min. To the
suspension was slowly added 1-cyclopropylmethanol (100 mmol)
for 25 min. The mixture was warmed to room temperature and
stirred for 3 h before flash distillation to collect a volatile product,
chlorocyclopropylmethane (7.9 g, 88%).1a To a solution of n-
butyllithium (1.6 M in hexane, 47 mL) in THF (80 mL) at 0 °C
was slowly added diisopropylamine (75 mmol), and the mixture
was stirred for 20 min. To the mixture was slowly added Bu3SnH
(75 mmol) for 30 min, and the mixture was stirred for 15 min to
generate Bu3SnLi. 1-Chloro-1-cyclopropylmethane (70 mmol) was
slowly added to the mixture for 30 min, which was warmed to
room temperature. After stirring for 16 h KF(aq) (10%, 200 mL)
a All entries were carried out at room temperature in solvent (1 mL)
with 1.0 mmol of 1, 1.0 mmol of 2, and 0.5 mmol of InBr3. Tin
compound 1 was added to the mixture of 2 and InBr3 in toluene.
b Iodocarbonyl 2 was added to the mixture of 1 and InBr3 in toluene that
had been previously stirred at room temperature for 30 min. c Reactions
were carried out on the bench using a nitrogen-flowing flask. d Reactions
were carried out at 100 °C.
the tertiary iodoester 2j resulted in a low yield (entry 11). Instead
of iodoesters, iodoamide 2k and iodoketone 2l gave the
corresponding products in satisfactory yields (entries 12 and
13). A conventional reaction procedure, which used a nitrogen-
flow flask on the bench whereby a very small amount of oxygen
was introduced, gave yields that were nearly identical to those
obtained under air, although in some cases lower yields were
obtained.
(14) Loiseau, F.; Simone, J.-M.; Carcache, D.; Bobal, P.; Neier, R.
Monatsh. Chem. 2007, 138, 121–129.
(15) Curran, D. P.; Tamine, J. J. Org. Chem. 1991, 56, 2746–2750.
(16) Neu, H.; Kihlblerg, T.; Långstro¨m, B. J. Labelled Compd. Radiop-
harm. 1997, 39, 509–524.
Conclusion
(17) Kihara, N.; Ollivier, C.; Renaud, P. Org. Lett. 1999, 1, 1419–1422.
(18) Denmark, S. E.; Yang, S.-M. J. Am. Chem. Soc. 2004, 126, 12432–
12440.
(19) Hlavinka, M. L.; Greco, J. F.; Hagadorn, J. R. Chem. Commun.
2005, 5304–5306.
This paper describes the transmetalation of cyclopropylm-
ethylstannane with indium halides to give dibutenylindium
halide and butenylindium dihalide. This transmetalation can be
applied to the reactions with iodocarbonyls to give coupling
products that bear cyclopropyl groups. This reaction does not
(20) Yin, G.; Zhou, B.; Meng, X.; Wu, A.; Pan, Y. Org. Lett. 2006, 8,
2245–2248.
(21) HA and HB are defined as hydrogens that are cis and trans to RCH-
cyclopropyl, respectively.
(13) The conditions without air employed on the bench might have
enough oxygen during the experimental process. A very small amount of
oxygen resulted in high efficiency in this case.
(22) Hayashi, K.; Iyoda, J.; Shiihara, I. J. Organomet. Chem. 1967, 10,
81–94.

Radical Coupling of Iodocarbonyl Compounds
Organometallics, Vol. 28, No. 1, 2009 137
was poured into the mixture. EtOAc (200 mL) was added, and the
organic layer was washed using saturated NaCl(aq) (200 mL) and
H2O (200 mL). After drying with MgSO4 the solvent was
evaporated and the residue was purified by column chromatography
(hexane) on silica gel and distillation under reduced pressure to
0.05 mmHg. The spectral data of the obtained bromoester (benzyl
2-bromopropanoate) were in excellent agreement with the reported
data.24 To a stirred solution of sodium iodide (100 mmol) in acetone
(100 mL) was added benzyl 2-bromopropanoate (50 mmol). The
mixture was stirred for 8 h, and then the solvent was evaporated.
Ethyl acetate (200 mL) was added, and the organic layer was
washed by Na2S2O3 (aq) (10%, 100 mL) and water (100 mL × 2)
and then dried (MgSO4). The solvent was evaporated, and the
residue was purified by distillation under reduced pressure to give
1
give the product (9.4 g, 37%): bp 78 °C/0.07 mmHg; H NMR
(400 MHz, CDCl3) 1.49 (m, 6H, 2′-H2 × 3), 1.31 (tq, J ) 7.2, 7.2
Hz, 6H, 3′-H2 × 3), 0.96-0.69 (m, 18H, 4′-H3 × 3, 1′-H2 × 3,
1-H2 and SnCH2CH), 0.46 (m, 2H, HA × 2), -0.04 (m, 2H, HB ×
2
2); 13C NMR (100 MHz, CDCl3) 29.4 (t, C-2′, d, JSn-C ) 19.7
1
the product (12.4 g, 82%): bp 84 °C/0.06 mmHg; H NMR (400
Hz), 27.5 (t, C-3′, d, 3JSn-C ) 52.4 Hz), 15.0 (t, C-1, d, 1J119Sn-C
)
MHz, CDCl3) 7.42-7.30 (m, 5H, Ar), 5.17 (m, 2H, C6H5CH2),
1
4.51 (q, J ) 7.2 Hz, 1H, 2-H), 1.97 (d, J ) 7.2 Hz, 3H, 3-H3); 13
C
307.2, J117Sn-C ) 293.3 Hz), 13.8 (q, C-4′), 9.2 (d, SnCH2CH, d,
1
1
2JSn-C ) 19.7 Hz), 9.0 (t, C-1′, d, J119Sn-C ) 312.1, J117Sn-C
)
NMR (100 MHz, CDCl3) 171.6 (s, C-1), 135.2 (s, i), 128.5 (d),
128.4 (d, p), 128.2 (d), 67.4 (t, C6H5CH2), 23.2 (q, C-3), 12.8 (d,
C-2); IR (neat) 1736 (CdO) cm-1; MS (CI, 200 eV) m/z 291 (M
+ 1, 13), 91 (C6H5CH2+, 100); HRMS (CI, 200 eV) calcd for
(C10H12IO2) 290.9882 (M + 1), found for m/z 290.9894. Anal. Calcd
for C10H11IO2: C, 41.40; H, 3.82; I, 43.75. Found: C, 41.63; H,
3.78; I. 43.92.
299.0 Hz), 8.3 (t, two methylene groups in cyclopropyl ring, d,
3JSn-C ) 34.4 Hz); 119Sn NMR (150 MHz, CDCl3) -15.6; IR (neat)
2958, 2924, 1462 cm-1; MS (EI, 70 eV) m/z 291 (39), 289 (86),
288 (31), 287 (59), 285 (28), 235 (57), 233 (57), 231 (37), 179
(94), 178 (29), 177 (100), 176 (34), 175 (70), 173 (22), 121 (31),
119 (24); HRMS (EI, 70 eV) calcd for (C12H27120Sn) 291.1135 (M
- CH2C3H5), found for m/z 291.1104 and calcd for (C12H25120Sn)
289.0978 (M - Bu), found for m/z 289.1048. Anal. Calcd for
C16H34Sn: C, 55.68; H, 9.93. Found: C, 55.47; H, 9.91.
Phenyl 2-Iodo-2-methylpropanoate (2j). To a stirred solution
of phenol (110 mmol) and sulfuric acid (95%, 0.3 mL) in toluene
(65 mL) was added 2-bromo-2-methylpropionyl bromide (110
mmol). The mixture was heated to reflux for 5 h and then cooled
to room temperature and quenched by water (200 mL). Ethyl acetate
(200 mL) was added, and the organic layer was washed by KOH(aq)
(10%, 200 mL) and water (200 mL) and then dried (MgSO4). The
solvent was evaporated, and the residue was purified by distillation
under reduced pressure to give the bromoester (21.6 g, 81%), bp
63 °C/0.04 mmHg. The spectral data of the obtained bromoester
were in excellent agreement with the reported data.25 To a stirred
solution of sodium iodide (160 mmol) in acetone (80 mL) was
added phenyl 2-bromo-2-methylpropanoate (40 mmol). The mixture
was heated to reflux for 14 h and then cooled to room temperature,
and acetone was evaporated. Ethyl acetate (200 mL) was add-
ed, and the organic layer was washed by Na2S2O3(aq) (10%, 100
mL) and water (100 mL × 2) and then dried (MgSO4). The solvent
was evaporated, and the residue was purified by distillation under
reduced pressure to give the product (8.72 g, 75%): bp 100 °C/0.6
Phenyl 2-Iodoacetate (2a). To a stirred solution of sodium iodide
(135 mmol) in acetone (150 mL) was added phenyl bromoacetate
(45 mmol). The mixture was stirred for 3 h, and then acetone was
evaporated. Ethyl acetate (200 mL) was added, and the organic
layer was washed by Na2S2O3(aq) (10%, 200 mL) and water (2 ×
200 mL) and then dried (MgSO4). The solvent was evaporated and
the residue was purified by recrystallization to give the product
1
(10.5 g, 90%): mp 65-67 °C; H NMR (400 MHz, CDCl3) 7.40
(dd, J ) 8.0, 8.0 Hz, 2H, m), 7.25 (t, J ) 8.0 Hz, 1H, p), 7.11 (d,
J ) 8.0 Hz, 2H, o), 3.90 (s, 2H, 2-H2); 13C NMR (100 MHz, CDCl3)
167.5 (s, C-1), 150.5 (s, C-i), 129.5 (d, C-m), 126.2 (d, C-p), 120.9
(d, C-o), -6.0 (t, C-2); IR (KBr) 1736 (CdO) cm-1; MS (EI, 70
eV) m/z 262 (M+, 8), 94 (100); HRMS (EI, 70 eV) calcd for
(C8H7IO2) 261.9491 (M+), found for m/z 261.9475. Anal. Calcd
for C8H7IO2: C, 36.67; H, 2.69; I, 48.43. Found: C, 36.68; H, 2.63;
I, 48.70.
1
Benzyl 2-Iodoacetate (2b). To a stirred solution of sodium iodide
(30 mmol) in acetone (60 mL) was added benzyl 2-chloroacetate
(30 mmol). The mixture was stirred for 3 h, and then acetone was
evaporated. Ethyl acetate (200 mL) was added, and the organic
layer was washed by Na2S2O3(aq) (10%, 100 mL) and water (100
mL × 2) and then dried (MgSO4). The solvent was evaporated,
and the residue was purified by distillation under reduced pressure
mmHg; H NMR (400 MHz, CDCl3) 7.40 (dd, J ) 8.0, 8.0 Hz,
2H, m), 7.25 (t, J ) 8.0 Hz, 1H, p), 7.13 (d, J ) 8.0 Hz, 2H, o),
2.20 (s, 6H, 3-H3 and 2-Me); 13C NMR (100 MHz, CDCl3) 171.9
(s, C-1), 150.7 (s, i), 129.4 (d, m), 126.0 (d, p), 120.8 (d, o), 33.5
(q, C-3 and 2-Me); IR (neat) 1747 (CdO) cm-1; MS (EI, 70 eV)
m/z 290 (M+, 28), 197 (COC(CH3)2I+, 48), 169 (C(CH3)2I+, 100),
+
163 (C6H5OCOC(CH3)2+, 76), 135 (64), 94 (85), 70 (COC(CH3)2
,
1
to give the product (6.7 g, 80%): bp 75 °C/0.1 mmHg; H NMR
28), 69 (22), 41 (38); HRMS (EI, 70 eV) calcd for C10H11IO2
289.9804 (M+), found for m/z 289.9822. Anal. Calcd for C10H11IO2:
C, 41.40; H, 3.82; I, 43.75. Found: C, 41.65; H, 3.68; I, 43.59.
(400 MHz, CDCl3) 7.40-7.30 (m, 5H, Ar), 5.15 (s, 2H, C6H5CH2),
3.71 (s, 2H, 2-H2); 13C NMR (100 MHz, CDCl3) 168.5 (s, C-1),
135.0 (s, C-i), 128.5 (d), 128.4 (d, C-p), 128.2, (d), 67.7 (t,
C6H5CH2), -5.5 (t, C-2); IR (neat) 1732 (CdO) cm-1; MS (EI, 70
eV) m/z 276 (M+, 0.04), 149 (C6H5CH2OCOCH2+, 89), 107
(C6H5CH2O+, 100), 91 (C6H5CH2+, 90); HRMS (EI, 70 eV) calcd
for (C9H9IO2) 275.9647 (M+), found for m/z 275.9655. Anal. Calcd
for C9H9IO2: C, 39.16; H, 3.29; I, 45.97. Found: C, 39.07; H, 3.16;
I, 45.96.
Benzyl 2-Iodopropanoate (2f). To a stirred solution of benzyl
alcohol (110 mmol) and pyridine (120 mmol) in CH2Cl2 (80 mL)
at 0 °C was slowly added a solution of 2-bromopropionyl bromide
(120 mmol) in CH2Cl2 (20 mL) for 25 min.23 The mixture was
warmed to room temperature, stirred for 12 h, and then quenched
by water (200 mL). Chloroform (200 mL) was added, and the
organic layer was washed by 1 M HCl aq (200 mL) and saturated
NaHCO3(aq) (200 mL) and then dried (MgSO4). The solvent was
evaporated, and the residue was purified by distillation under
reduced pressure to give the bromoester (24.0 g, 87%), bp 78 °C/
Procedure for Optimization of Coupling of Cyclopropylm-
ethylstannane 1 and Iodocarbonyls 2 (Table 1). According to
the next paragraph, the reactions were employed under the
conditions noted in text.
General Procedure for InBr3-Mediated Coupling of Cyclo-
propylmethylstannane 1 and Iodocarbonyls 2 (Table 2). To a
suspension of InBr3 (0.5 mmol) and iodocarbonyls 2 (1 mmol) in
toluene (1 mL) was added (cyclopropylmethyl)tributylstannane 1
(1 mmol) with a CaCl2 drying tube that was exposed to air. The
reaction mixture was stirred at rt for 4.5 h. The mixture was
quenched by addition of NH4F(aq) (10%, 10 mL) and extracted
with diethyl ether (3 × 10 mL). The collected organic layer was
dried over MgSO4 and concentrated in Vacuo. The procedures used
for further purification of the new compounds are shown in the
(24) DeGraw, J. I.; Christie, P. H.; Kisliuk, R. L.; Gaumont, Y.; Sirotnak,
F. M. J. Med. Chem. 1990, 33, 212–215.
(23) Kakiya, H.; Nishimae, S.; Shinokubo, H.; Oshima, K. Tetrahedron
2001, 57, 8807–8815.
(25) Schick, H.; Ludwig, R.; Kleiner, K.; Kunath, A. Tetrahedron 1995,
51, 2939–2946.

138 Organometallics, Vol. 28, No. 1, 2009
Yasuda et al.
Product Data section. The reactions under nitrogen were performed
using the same operation.
Allyl 3-Cyclopropylpropanoate (3d).21 According to the general
procedure, this compound was prepared from 1 and 2d to give the
product as a colorless liquid after chromatography (hexane/EtOAc
) 94/6). Further purification was performed by distillation under
NMR Study of Transmetalation between 1 and 2 (Figure
2). Three mixtures with different ratios of InBr3/1 () 1/1, 1/2, and
1/3) were prepared in toluene-d8. After mixing for ca. 2 h, the
mixtures were transferred into NMR tubes, and the resulting spectra
are shown in Figure 2.
1
reduced pressure. Bp: 120 °C/30 mmHg; H NMR (400 MHz,
CDCl3) 5.93 (ddt, J ) 17.6, 10.4, 5.6 Hz, 1H, CH2CHCH2OCO),
5.32 (ddd, J ) 17.6, 3.2, 1.6 Hz, 1H, CH2CHdCHH), 5.24 (ddd,
J ) 10.4, 3.2, 1.6 Hz, 1H, CH2CHdCHH), 4.58 (ddd, J ) 5.6,
1.6, 1.6 Hz, 2H, CH2CHCH2OCO), 2.44 (t, J ) 7.2 Hz, 2H, 2-H2),
1.63 (dt, J ) 7.2, 7.2 Hz, 2H, 3-H2), 0.72 (ttt, J ) 8.0, 5.6, 7.2 Hz,
Product Data. The spectral data of 3e,26 3f,4 3i,4 3k,4 and 3l4
were in excellent agreement with the reported data. Spectral data
for the products 3a, 3b, 3c, 3d, 3g, 3h, and 3j are shown below.
Phenyl 3-Cyclopropylpropanoate (3a).21 According to the gen-
eral procedure, this compound was prepared from 1 and 2a to give
the product as a colorless liquid after chromatography (hexane).
Further purification was performed by distillation under reduced
pressure. Bp 90 °C/0.07 mmHg; 1H NMR (400 MHz, CDCl3) 7.38
(dd, J ) 8.0, 7.2 Hz, 2H, m), 7.22 (t, J ) 7.2 Hz, 1H, p), 7.08 (d,
J ) 8.0 Hz, 2H, o), 2.66 (t, J ) 7.2 Hz, 2H, 2-H2), 1.66 (dt, J )
7.2, 7.2 Hz, 2H, 3-H2), 0.81 (ttt, J ) 8.0, 7.2, 5.6 Hz, 1H,
COCH2CH2CH), 0.49 (ddd, J ) 8.0, 5.6, 4.8 Hz, 2H, HA × 2),
0.13 (ddd, J ) 5.6, 5.6, 4.8 Hz, 2H, HB × 2); 13C NMR (100 MHz,
CDCl3) 172.1 (s, C-1), 150.7 (s, C-i), 129.3 (d, C-m), 125.7 (d,
C-p), 121.5 (d, C-o), 34.5 (t, C-2), 30.0 (t, C-3), 10.4 (d,
COCH2CH2CH), 4.5 (t, two methylene groups in cyclopropyl ring);
IR (neat) 1759 (CdO) cm-1; MS (EI, 70 eV) m/z 190 (M+, 37),
97 (COCH2CH2C3H5+, 34), 94 (100), 69 (CH2CH2C3H5+, 44), 55
(CH2C3H5+, 24); HRMS (EI, 70 eV) calcd for (C12H14O2) 190.0994
(M+), found for m/z 190.1000.
1H, COCH2CH2CH), 0.43 (ddd, J ) 8.0, 5.6, 4.0 Hz, 2H, HA
×
2), 0.06 (ddd, J ) 5.6, 5.6, 4.0 Hz, 2H, HB × 2); 13C NMR (100
MHz, CDCl3) 173.4 (s, C-1), 132.3 (d, CH2CHCH2OCO), 118.1
(t, CH2CHCH2OCO), 65.0 (t, CH2CHCH2OCO), 34.4 (t, C-2), 30.1
(t, C-3), 10.5 (d, COCH2CH2CH), 4.4 (t, two methylene groups in
cyclopropyl ring); IR (neat) 1739 (CdO), 1651 (CdC) cm-1; MS
(CI, 200 eV) m/z 155 (M + 1, 100); HRMS (CI, 200 eV) calcd for
(C9H15O2) 155.1072 (M + 1), found for m/z 155.1080.
Phenyl 3-Cyclopropyl-2-methylpropanoate (3g).21 According
to the general procedure, this compound was prepared from 1 and
2f to give the product as a colorless liquid after chromatography
(hexane/EtOAc ) 94/6). Further purification was performed by
distillation under reduced pressure. Bp: 95 °C/0.15 mmHg; 1H NMR
(400 MHz, CDCl3) 7.38 (dd, J ) 8.0, 7.2 Hz, 2H, m), 7.22 (t, J )
7.2 Hz, 1H, p), 7.08 (d, J ) 8.0 Hz, 2H, o), 2.81 (tq, J ) 7.2, 7.2
Hz, 1H, 2-H), 1.69 (ddd, J ) 14.4, 7.2, 7.2 Hz, 1H, 3-HH), 1.53
(ddd, J ) 14.4, 7.2, 7.2 Hz, 1H, 3-HH), 1.34 (d, J ) 7.2 Hz, 3H,
2-Me), 0.82 (m, 1H, COCH(CH3)CH2CH), 0.50 (m, 2H, HA × 2),
0.13 (m, 2H, HB × 2); 13C NMR (100 MHz, CDCl3) 175.1 (s, C-1),
150.7 (s, i), 129.3 (d, m), 125.5 (d, p), 121.4 (d, o), 40.2 (d, C-2),
38.6 (t, C-3), 16.9 (q, 2-Me), 8.8 (d, COCH(CH3)CH2CH), 4.6 (t,
COCH(CH3)CH2CHCAH2), 4.4 (t, COCH(CH3)CH2CHCBH2); IR
(neat) 1759 (CdO) cm-1; MS (EI, 70 eV) m/z 204 (M+, 28), 111
(COCH(CH3)CH2C3H5+, 54), 94 (88), 83 (CH(CH3)CH2C3H5+, 70),
55 (CH2C3H5+, 100); HRMS (EI, 70 eV) calcd for (C13H16O2)
204.1150 (M+), found for m/z 204.1145. Anal. Calcd for C13H16O2:
C, 76.44; H, 7.90. Found: C, 76.15; H, 7.74.
Benzyl 3-Cyclopropylpropanoate (3b).21 According to the gen-
eral procedure, this compound was prepared from 1 and 2b to give
the product as a colorless liquid after chromatography (hexane/
EtOAc ) 95/5). Further purification was performed by distillation
under reduced pressure. Bp 77 °C /0.2 mmHg; 1H NMR (400 MHz,
CDCl3) 7.41-7.28 (m, 5H, Ar), 5.12 (s, 2H, C6H5CH2), 2.46 (t, J
) 7.2 Hz, 2H, 2-H2), 1.54 (dt, J ) 7.2, 7.2 Hz, 2H, 3-H2), 0.70
(ttt, J ) 8.0, 5.6, 7.2 Hz, 1H, COCH2CH2CH), 0.40 (ddd, J ) 8.0,
5.6, 4.0 Hz, 2H, HA × 2), 0.05 (ddd, J ) 5.6, 5.6, 4.0 Hz, 2H, HB
x 2); 13C NMR (100 MHz, CDCl3) 173.5 (s, C-1), 136.1 (s, C-i),
128.5 (d), 128.2 (d), 128.1 (d, C-p), 66.1 (t, C6H5CH2), 34.4 (t,
C-2), 30.4 (t, C-3), 10.4 (d, COCH2CH2CH), 4.4 (t, two methylene
groups in cyclopropyl ring); IR (neat) 1736 (CdO) cm-1; MS (EI,
70 eV) m/z 204 (M+, 0.71), 104 (61), 91 (C6H5CH2+, 100); HRMS
(EI, 70 eV) calcd for C13H16O2 204.1150 (M+), found for m/z
204.1139. Anal. Calcd for C13H16O2: C, 76.44; H, 7.90. Found: C,
76.52; H, 7.71.
Ethyl 3-Cyclopropyl-2-methylpropanoate (3h).21 According
to the general procedure, this compound was prepared from 1 and
2h to give the product as a colorless liquid after chromatography
(hexane/EtOAc ) 94/6). Further purification was performed by
distillation under reduced pressure. Bp: 100 °C/10 mmHg; 1H NMR
(400 MHz, CDCl3) 4.13 (q, J ) 7.2 Hz, 2H, CH3CH2OCO), 2.53
(tq, J ) 7.2, 7.2 Hz, 1H, 2-H), 1.53 (ddd, J ) 14.4, 7.2, 7.2 Hz,
1H, 3-HH), 1.37 (ddd, J ) 14.4, 7.2, 7.2 Hz, 1H, 3-HH), 1.26 (t,
J ) 7.2 Hz, 3H, CH3CH2OCO), 1.18 (d, J ) 7.2 Hz, 3H, 2-Me),
0.69 (m, 1H, COCH2CH2CH), 0.43 (m, 2H, HA × 2), 0.04 (m, 2H,
HB × 2); 13C NMR (100 MHz, CDCl3) 176.8 (s, C-1), 60.1 (t,
CH3CH2OCO), 40.1 (d, C-2), 38.7 (t, C-3), 17.0 (q, 2-Me), 14.2
(q, CH3CH2OCO), 8.9 (d, COCH(CH3)CH2CH), 4.5 (t,
COCH(CH3)CH2CHCAH2), 4.2 (t, COCH(CH3)CH2CHCBH2); IR
(neat) 1736 (CdO) cm-1; MS (EI, 70 eV) m/z 156 (M+, 14), 128
Ethyl 3-Cyclopropylpropanoate (3c).21 According to the gen-
eral procedure, this compound was prepared from 1 and 2c to give
the product as a colorless liquid after chromatography (hexane/
EtOAc ) 94/6). Further purification was performed by distillation
under reduced pressure. Bp 90 °C/20 mmHg; 1H NMR (400 MHz,
CDCl3) 4.13 (q, J ) 7.2 Hz, 2H, CH3CH2OCO), 2.39 (t, J ) 7.2
Hz, 2H, 2-H2), 1.53 (dt, J ) 7.2, 7.2 Hz, 2H, 3-H2), 1.26 (t, J )
7.2 Hz, 3H, CH3CH2OCO), 0.71 (m, 1H, COCH2CH2CH), 0.43
(ddd, J ) 8.0, 5.6, 4.0 Hz, 2H, HA × 2), 0.05 (m, 2H, HB × 2);
13C NMR (100 MHz, CDCl3) 173.7 (s, C-1), 60.1 (t, CH3CH2OCO),
34.5 (t, C-2), 30.1 (t, C-3), 14.2 (q, CH3CH2OCO), 10.4 (d,
COCH2CH2CH), 4.3 (t, two methylene groups in cyclopropyl ring);
(CH3CH2OCOCH(CH3)CH2CH+, 70), 102 (65), 87 (36), 83
+
(CH(CH3)CH2C3H5+, 48), 74 (100), 55 (CH2C3H5+, 91), 41 (C3H5
,
25); HRMS (EI, 70 eV) calcd for (C9H16O2) 156.1150 (M+), found
for m/z 156.1139.
IR (neat) 1739 (CdO) cm-1; MS (EI, 70 eV) m/z 142 (M+, 15),
Phenyl 3-Cyclopropyl-2,2-dimethylpropanoate (3j).21 Accord-
ing to the general procedure, this compound was prepared from 1
and 2j to give the product as a colorless liquid after chromatography
114 (CH3CH2OCOCH2CH2CH+, 70), 113 (OCOCH2CH2C3H5
,
+
20), 99 (CH2OCOCH2CH2C3H5+, 32), 97 (COCH2CH2C3H5+, 64),
96 (21), 88 (96), 73 (CH3CH2OCO+, 42), 71 (27), 70 (32), 69
(CH2CH2C3H5+, 100), 68 (88), 67 (22), 61 (36), 60 (88),
55(CH2C3H5+, 71), 54 (27), 42 (22), 41 (C3H5+, 74), 39 (31); HRMS
(EI, 70 eV) calcd for (C8H14O2) 142.0994 (M+), found for m/z
142.1010.
1
(hexane/EtOAc ) 94/6) and recycle GPC. H NMR (400 MHz,
CDCl3) 7.38 (dd, J ) 8.0, 7.2 Hz, 2H, m), 7.22 (t, J ) 7.2 Hz, 1H,
p), 7.08 (d, J ) 8.0 Hz, 2H, o), 1.63 (d, J ) 7.2 Hz, 2H, 3-H2),
1.36 (s, 6H, 2-Me2), 0.79 (ttt, J ) 8.0, 7.2, 4.8 Hz, 1H,
COC(CH3)2CH2CH), 0.50 (ddd, J ) 8.0, 5.6, 4.0 Hz, 2H, HA
×
2), 0.13 (ddd, J ) 5.6, 4.8, 4.0 Hz, 2H, HB × 2); 13C NMR (100
MHz, CDCl3) 176.5 (s, C-1), 151.0 (s, i), 129.3 (d, m), 125.5 (d,
p), 121.4 (d, o), 45.4 (t, C-3), 43.4 (s, C-2), 25.3 (q, 2-Me2), 7.0
(26) Orsini, F.; Pelizzoni, F.; Ricca, G. Tetrahedron 1984, 40, 2781–
2787.

Radical Coupling of Iodocarbonyl Compounds
Organometallics, Vol. 28, No. 1, 2009 139
(d, COC(CH3)2CH2CH), 4.5 (t, two methylene groups in cyclopropyl
ring); IR (neat) 1751 (CdO) cm-1; MS (EI, 70 eV) m/z 218 (M+,
3), 125 (COC(CH3)2CH2C3H5+, 50), 97 (C(CH3)2CH2C3H5+, 84),
96 (28), 94 (84), 81 (30), 55 (CH2C3H5+, 100); HRMS (EI, 70 eV)
calcd for (C14H18O2) 218.1307 (M+), found for m/z 218.1367. Anal.
Calcd for C14H18O2: C, 77.03; H, 8.31. Found: C, 76.76; H, 8.29.
Dibutenylindium Chloride-DPPE Complex (9). To a suspen-
sion of InCl3 (0.5 mmol) in toluene (1 mL) was added (cyclopro-
pylmethyl)tributylstannane (1; 1 mmol) at rt. The mixture was
stirred for 2 h, and then 1,2-bis(diphenylphosphino)ethane (0.25
mmol) was loaded. The mixture was stirred for 1 h, and then the
volatiles were evaporated to give a viscous liquid, which was then
washed by hexane to give the product as a white solid (95 mg,
42%). The product was recrystallized from dichloromethane/hexane
for X-ray analysis. The data obtained from the measurement was
good (Rint ) 0.056), and the analysis was completed to optimize
the structure. Although some level A alerts still remain, this structure
should be justified because of the excellent level of the data and
J ) 16.8, 1.6 Hz, 4H, 4-HH × 4), 4.88 (dd, J ) 9.6, 1.6 Hz, 4H,
4-HH × 4), 2.38 (dt, J ) 7.2, 6.4 Hz, 8H, 2-H2 × 4), 2.36 (m, 4H,
PCH2CH2P), 1.11 (t, J ) 7.2 Hz, 8H, 1-H2 × 4); 13C NMR (100
2
MHz, CDCl3) 142.7 (C-3), 132.8 (o, d, JP-C ) 15.6 Hz), 132.3
(i), 130.2 (p), 129.0 (m, d, 3JP-C ) 8.2 Hz), 113.1 (C-4), 30.9 (C-
1
2), 21.9 (PCH2CH2P, d, JP-C ) 9.8 Hz), 20.4 (C-1).
Acknowledgment. This work was supported by Grants-in-
Aid for Scientific Research on Priority Areas (No. 18065015,
“Chemistry of Concerto Catalysis” and No. 20036036, “Syn-
ergistic Effects for Creation of Functional Molecules”) and for
Scientific Research (No. 19550038) from the Ministry of Edu-
cation, Culture, Sports, Science and Technology, Japan.
Supporting Information Available: Results of NMR experi-
ment of the reaction of varying 2a and crystallographic data for 9.
This material is available free of charge via the Internet at
http://pubs.acs.org.
1
structure refinement. H NMR (400 MHz, CDCl3) 7.47-7.31 (m,
20H, Ar), 5.89 (ddt, J ) 16.8, 9.6, 6.4 Hz, 4H, 3-H × 4), 4.95 (dd,
OM8009156