Transition metal-catalyzed carbostannylation of alkynes and dienes

Article abstract of DOI:10.1246/bcsj.75.1435

Carbon-tin bonds in alkynyl-, allyl-, acyl-, alkenyl-, and arylstannanes were found to add to carbon-carbon unsaturated bonds of alkynes, 1,3-dienes and 1,2-dienes in the presence of a catalytic amount of palladium or nickel complexes to give alkenyl- or

Full text of DOI:10.1246/bcsj.75.1435

Bull. Chem.
Soc. Jpn.
75
7
© 2002 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 75, 1435–1450 (2002) 1435
The Chemical
Society of Ja-
pan
The Chemical
Society of Ja-
pan
Accounts
OB
7
15
Transition Metal-Catalyzed Carbostannylation of Alkynes and Dienes
2002
1435
1450
BCSJA8
0009-2673
A1328
12
E. Shirakawa et al.
Eiji Shirakawa* and Tamejiro Hiyama*,†
Graduate School of Materials Science, Japan Advanced Institute of Science and Technology,
Asahidai, Tatsunokuchi, Ishikawa 923-1292
14
2001
1
†Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501
(Received December 14, 2001)
24
2002
Carbon–tin bonds in alkynyl-, allyl-, acyl-, alkenyl-, and arylstannanes were found to add to carbon–carbon unsat-
urated bonds of alkynes, 1,3-dienes and 1,2-dienes in the presence of a catalytic amount of palladium or nickel complex-
es to give alkenyl- or allylstannanes having various functional groups. Mechanisms are proposed that start with oxidative
addition of a carbon–tin bond, or palladacycle formation followed by β-tin elimination or by the reaction with an orga-
nostannane.
4.10
Organostannanes are widely used synthetic precursors that
react with various organic electrophiles in the presence of ap-
propriate activators.1 Due to the modest nucleophilicity of or-
ganostannanes, the palladium-catalyzed cross-coupling reac-
tion of organostannanes proceeds with tolerance toward vari-
ous functional groups, being called the Kosugi–Migita–Stille
reaction, and has become one of the most important carbon–
carbon bond forming reactions.1,2 Easy handling and high
chemoselectivity of allylstannanes are utilized for the reaction
with Lewis acid-activated carbonyl groups.1,3 Organostan-
nanes are usually prepared by a method involving the reaction
of trialkyltin halides with other organometallic reagents. This
works well particularly for syntheses of simple ones. Howev-
er, organostannanes having an electrophilic functional group
like a carbonyl or hydroxy group cannot be obtained by the
method without troublesome protection and deprotection
steps. By appropriate activation of carbon–tin bonds, car-
bostannylation of unsaturated bonds would be possible, we
considered, giving organostannanes of much more complex
structures with labile functional groups. When we started our
study on the carbostannylation of alkynes, however, there were
only two precedents:4,5,6 both were limited to allylstannanes
and afforded anti-adducts without any late transition metal cat-
alyst. For example,Yamamoto and his co-workers reported the
Lewis acid-catalyzed allylstannylation of alkynes, using Lewis
acids to activate carbon–carbon triple bonds.7 On the other
hand, Hosomi’s group disclosed the radical reaction of allyl-
stannanes with alkynes or alkenes initiated by AIBN and ob-
tained the corresponding anti-allylstannylation products.8
In this account, we briefly summarize a novel synthetic
methodology through the palladium- or nickel-catalyzed car-
bostannylations of unsaturated carbon–carbon bonds of
alkynes, 1,3-dienes, and 1,2-dienes. The synthetic transforma-
tions have been accomplished on the basis of a new concept for
cleavage of carbon–tin bonds by transition metal complexes
and are considered to work through (Scheme 1): (i) oxidative
addition of carbon–tin bonds to a palladium(0) or nickel(0)
complex, (ii) β-tin elimination from palladacyclopent-2-enes
generated by oxidative cyclization of allylstannanes and
alkynes with a palladium(0) complex, or (iii) reaction of orga-
nostannanes with palladacyclopentadienes derived from two
molecules of alkynes and a palladium(0) complex.
Scheme 1.

1436 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
nylstannylation with arylacetylenes, conjugated ynoates, prop-
1. Carbostannylation of Alkynes
argyl (2-propynyl) amides and propargyl ethers, and the corre-
sponding products were isolable in high yields as mixtures (5
and 6) of regioisomers.
Before our discovery of the carbostannylation of carbon–
carbon unsaturated bonds, we had been studying the cross-
coupling reaction of alkynylstannane 1a with aryl iodide 2 us-
ing a palladium(0) complex and N-(2-diphenylphosphinoben-
zylidene)-2-phenylethylamine (IP)9 ligand and had observed
that the reaction proceeded through oxidative addition of the
alkynylstannane to a palladium(0)–IP complex (Cycle A in
Scheme 2).10,11,12 The mechanism contrasts sharply to the
well-accepted catalytic cycle of the cross-coupling reaction
with organostannanes as well as with other organometallic
compounds, a reaction documented to start with oxidative ad-
dition of an aryl halide (Cycle B in Scheme 2).2,13 A palladium
complex with 1,3-bis(diphenylphosphino)propane (DPPP)
also was found to undergo the oxidative addition with 1a, but
the resulting oxidative adduct in this case did not participate in
the reaction; the reaction actually proceeds via Cycle B! This
observation was the first demonstration that a carbon–tin bond
could add oxidatively to a palladium(0) complex,14 whereas
oxidative addition of carbon–tin bonds to platinum(0) com-
plexes had some precedents.15 We envisaged that oxidative ad-
duct 3 might react with alkynes to give alkynylstannylation
products. Gratifyingly, the expected alkynylstannylation reac-
tion of alkynes did proceed highly effectively. Subsequently,
allyl- and acylstannylations of alkynes were disclosed.
(1)
Substituent R on nitrogen of the iminophosphine ligands
markedly affected the regioselectivity and reaction rate. A
ligand with bulkier R accelerated the reaction of methyl prop-
argyl ether with 1a and increased the regioselectivity as shown
in Eq. 2, although t-butyl turned out to be too bulky and retard-
ed the reaction. Iminophosphine IP(Cy) derived from cyclo-
hexylamine (R = c-Hex) turned out to be a well-balanced
ligand in view of activity and selectivity, and was effective also
for the reaction of propargyl amides and arylacetylenes. How-
ever, the reaction of ethyl propiolate with 1a, giving regioiso-
meric ratios opposite to those of propargyl ethers and arylacet-
ylenes, proceeded faster with a palladium complex of phenyl-
substituted iminophosphine IP(Ph). Selected results of alky-
nylstannylation of various alkynes using Pd–IP(Cy) or Pd–
IP(Ph) are summarized in Eq. 3 and Table 1.
(2)
Scheme 2.
1-1. Alkynylstannylation.16 We first examined the reac-
tion of 1a under an acetylenic atmosphere (1 atm) in THF (50
°C, 2 h) in the presence of [PdCl(η3-C3H5)]2–IP (5 mol% of
Pd, Pd/IP = 1) to find that alkynylstannylation product tribu-
tyl[(Z)-2-(phenylethynyl)ethenyl]tin was obtained in 81%
yield (Eq. 1). Use of triphenylphosphine or DPPP as a ligand
lowered the yield even after a prolonged reaction period. The
Pd–IP catalyst was applicable also to the stereoselective alky-
(3)
A nickel(0) complex prepared in situ from Ni(acac)2 and hy-
dridodiisobutylaluminum (1:2) also catalyzes the syn-selective
addition of alkynylstannanes to terminal alkynes (Eq. 4 and

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1437
Table 1. Alkynylstannylation of Alkynesa)
Entry
R1
R2
R3
Ligand Time/h
Yield/%b)
5ꢀ:6ꢀc)
1
2d)
3
4
5
Ph MeOCH2
H
H
IP(Cy)
IP(Cy)
IP(Cy)
IP(Cy)
IP(Cy)
IP(Cy)
IP(Cy)
5
1
3
3
5
6
5
93
1
1
81
70
71
77
73
70
58
29
71
83
88
86
62
79 : 21
—
88 : 12
90 : 10
H
H
H
H
H
H
AcNHCH2
(CH2CO)2NCH2
Ph
4-MeC6H4
EtO
EtOCO
EtOCO
Ac
> 99 :
97 :
> 99 :
1
3
1
6
7e)
8f)
9
Me IP(Cy)
1 :> 99
7 : 93
13 : 87
—
H
H
H
H
H
IP(Ph)
IP(Cy)
IP(Cy)
IP(Cy)
IP(Ph)
10
11d)
12
13
Bu
H
2
12
24
Ph
EtOCO
> 99 :
1
7 : 93
a) The reaction was carried out in THF (3 mL) at 50 °C using an alkynylstannane (0.34
mmol) and an alkyne (1.0 mmol) in the presence of [PdCl(η3-C3H5)]2 (8.2 µmol), and
IP(Cy) or IP(Ph) (0.016 mmol). b) Isolated yields based on the alkynylstannane. c)
1
Determined by H or 119Sn NMR. d) The reaction was carried out under an acetylene
atmosphere (1 atm). e) Ethoxyacetylene (0.34 mmol) was used. f) Solvent = dioxane,
temperature = 90 °C.
Table 2). The most characteristic feature of the nickel catalyst
is high regioselectivity, where the stannyl group of alkynyl-
stannanes exclusively attacks the terminal acetylenic carbon.
Although the nickel complex cannot catalyze the addition to
electron-deficient alkynes, the palladium catalyst discussed
above can complement the reaction with such substrates.
(4)
Table 2. Alkynylstannylation of Alkynesa)
Entry R1
R2
Time/h Yield/%
Scheme 3.
1
2
3
4
5
Ph
Hex
Hex
Hex
24
4
72
82
70
56
79
2-CF3-C6H4
4-CF3-C6H4
4-MeO-C6H4 Hex
4-CF3-C6H4 Cyclohexen-1-yl
complex 3, with the phenylethynyl group being located cis to
the imino moiety as we reported before.10 Subsequently, an
alkyne, methyl propargyl ether here, would coordinate to a va-
cant coordination site generated by dissociation of the imino
group from palladium,17 insert into the C–Pd bond (carbopalla-
dation) of 3, and then undergoes reductive elimination to af-
ford the alkynylstannylation products, regenerating the palladi-
um(0) complex. Such a bulky substituent as a cyclohexyl
group in IP(Cy) is assumed to facilitate dissociation from the
palladium center and to accelerate alkyne insertion. Although
the dissociation might be easier with the t-butyl-substituted
iminophosphine, excessive bulkiness of t-Bu appears to inhibit
the coordination of an alkyne and to retard the reaction. The
bulkiness is definitely attributed also to the high regioselectivi-
ty. Thus, the steric repulsion between a methoxymethyl group
of the alkyne and the nitrogen substituent in iminophosphines
unfavorably influences the reaction efficiency but favorably in-
fluences the regioselectivity.
10
36
5
a) The reaction was carried out in toluene (0.5 mL) at 80 °C
using an alkynylstannane (0.76 mmol) and an alkyne (2.3
mmol) in the presence of a Ni(0) catalyst prepared in situ
from Ni(acac)2 (38 µmol) and a 1.5 M toluene solution of
hydridodiisobutylaluminum (76 µmol). b) Isolated yield
based on the alkynylstannane.
Since alkynylstannanes can oxidatively add to palladium–
iminophosphine complexes with ease, it seems pertinent to as-
sume that the catalytic cycle of the palladium-catalyzed alky-
nylstannylation is initiated by this process, though the follow-
ing steps may differ depending on the structure of the alkynes.
On the basis of ligand effects on reaction rate and regioselec-
tivity, we have proposed a catalytic cycle in Scheme 3 for the
palladium-catalyzed reaction of such alkynes as propargyl
ethers and arylacetylenes. Oxidative addition of phenylethy-
nylstannane 1a to a palladium(0) complex gives palladium(Ⅱ)
Electron-deficient alkynes are likely to undergo Michael-
type addition of an alkynyl group (Scheme 4), giving 6 pre-
dominantly through alkenylpalladium complex 8. At present,

1438 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Ni(cod)2 is more sensitive to the electronic character of R1 or
R2 (Eq. 5) than Pd2(dba)3, which favors the formation of
Michael-type products. Representative examples with ethyl 2-
butynoate can be seen in entries 4, 12, and 13.
The reaction of substituted allylstannanes has provided us
with an important clue to the mechanism of the palladium-cat-
alyzed allylstannylation of alkynes. Dimethyl acetylenedicar-
boxylate (4a) reacted with three isomers 9b, 9c, and 9d of
butenyl(tributyl)tins in the presence of 2.5 mol% of Pd2(dba)3.
Results are summarized in Eq. 6. α-Methylallylstannane 9b
adds to 4a, forming a bond exclusively at its γ-position. Re-
gioisomers of 9b, (E)-2-buten-1-yl(tributyl)tin (9c) and (Z)-2-
buten-1-yl(tributyl)tin (9d), reacted with 4a in different man-
ners, giving roughly equal amounts of α- and γ-adducts (12
and 13) in addition to dimerization–carbostannylation product
14. The configuration of the crotyl (2-butenyl) group in 9c or
9d was retained in 12, in contrast to the fact that 12 derived
from 9b consisted of a mixture of stereoisomers. α-Methylal-
lylstannane 9b and non-substituted allylstannane 9a, both
lacking the γ-methyl group, reacted much faster than 9c or 9d.
All these observations are explained rationally by the two cata-
lytic cycles depicted in Scheme 5, though results for the inter-
mediates remain to be studied. Thus, α-methylallylstannane
9b and 4a might first undergo oxidative cyclization with the
palladium(0) complex to afford palladacyclopentene 15 (Cycle
C). Oxidative cyclization of a terminal alkene and 4a with a
palladium(0) complex has a precedent.19 β-Tin elimination
from 15 would give 16, whose reductive elimination affords al-
lylstannylation product 12 as a mixture of stereoisomers. Cy-
cle C explains well the carbon–carbon bond formation at the γ-
carbon of allylstannanes. Steric repulsion between the γ-meth-
yl of crotylstannane 9c (or 9d) and the ester moiety on 4a
should prevent the formation of palladacyclopentene 15ꢀ, and
Scheme 4.
it is not clear why higher regioselectivity was observed with
IP(Ph) than with any other iminophosphine ligands. We do
not have any indications to clarify the reaction mechanism of
the nickel-catalyzed alkynylstannylation; the catalytic cycle
should at least include oxidative addition of an alkynylstan-
nane to a nickel(0) complex.
1-2. Allylstannylation.18,16b Allylstannylation of alkynes
also can be catalyzed by a palladium or nickel complex. Re-
sults summarized in Eq. 5 and Table 3 show that zero-valent
(5)
metals of nickel (Ni(cod)2) and palladium (Pd2(dba)3) without
any ligand do catalyze but again complement each other about
the scope of alkynes. The nickel catalyst allows most types of
alkynes to participate in the reaction, whereas the palladium
catalyst is effective only for highly electron-deficient alkynes.
Table 3. Allylstannylation of Alkynesa)
Entry R1
R2
Catalyst
Temp/°C Time/h Yield/%b)
10:11c)
1
2
3
4
5
6
7
8
9
10
11
12
13d)
14
15
16e)
Hex
H
Pr
H
H
Pr
CO2Et
Ph
Ph
CO2Et
CWCBu
CWCSiMe3 Ni(cod)2
CN
SO2(p-tol)
CO2Et
CO2Et
CO2Et
CF3
Ni(cod)2
Ni(cod)2
Ni(cod)2
Ni(cod)2
Ni(cod)2
Ni(cod)2
Ni(cod)2
Ni(cod)2
80
80
80
100
100
100
100
100
100
90
50
50
50
50
50
50
5
14
0.5
93
80
77
78
77
76
78
64
70
63
73
37
55
100
98
80
64:36
—
—
65:35
> 99:1
> 99:1
> 99:1
> 99:1
> 99:1
> 99:1
92:8
86:14
91:9
79:21
72:28
—
Me
Me
Me3Si
Me3Si
Bu
Me3Si
Bu
Ph
12
12
14
40
14
8
72
1
50
62
43
14
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Pd2(dba)3
Me
Me
Ph
Ph
MeOCO CO2Me
0.5
a) Entries 1–9: the reaction was carried out in toluene (0.3 mL) using allyl(tributyl)tin (0.46
mmol) and an alkyne (1.38 mmol) in the presence of Ni(cod)2 (23 µmol); entries 10–16:
the reaction was carried out in 1,4-dioxane (3.0 mL) at 50 °C using allyl(tributyl)tin (0.33
mmol), an alkyne (0.99 mmol) and Pd2(dba)3 (8.2 µmol). b) Isolated yield based on the
allylstannane. c) Determined by 119Sn NMR. d) [PhNwC(Me)]2 (16.4 µmol) was used. e)
A 1:2 adduct of the allylstannane and the alkyne was also obtained in 8% yield.

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1439
(6)
Scheme 5.
Scheme 6.
an alternative pathway, Cycle D, becomes plausible. Oxidative
addition of 9c to a palladium(0) complex should give 17,
which undergoes insertion of alkyne 4a to produce π-allylpal-
ladium(Ⅱ) complex 18. Reductive elimination from 18 would
provide dienylstannanes (E)-12 and 13, whereas trienylstan-
nane 14 is obtained by insertion of another molecule of 4a to
18 and the consequent reductive elimination.
The reactions of variously substituted allylstannanes with
electron-deficient alkynes proceeded in the presence of 2.5
mol% of Pd2(dba)3 (Scheme 6). α-Methylallylstannane 9b
added also to alkynes other than 4a to give γ-adducts exclu-
sively, whereas a γ-substituted allylstannane, tributyl(cin-
namyl)tin, afforded α-adducts as the sole products.
Scheme 7.
(E)-Crotylstannane 9c forms a bond exclusively at its α-posi-
tion, where the regioselectivity concerning an alkyne is per-
The nickel-catalyzed reaction using substituted allylstan-
nanes also provided allylstannylation products (Scheme 7).

1440 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Table 4. Acylstannylation of Alkynesa)
Entry R1 R2 R3
R4
Temp/°C Time/h Yield/%b) 20:21c)
1
2
3
4
5
6
7
8
9
Ph
Ph
Me Pr
Me Me
Pr
Ph
Pr
Ph
100
100
100
100
30
30
30
30
30
2
65
61
66
81
66
85
56
58
47
—
83:17
—
64:36
88:12
98:2
91:9
66:34
79:21
1.5
1.5
2
2.5
3
1.5
24
24
(CH2)5N Bu Pr
(CH2)5N Bu Me
Ph
Ph
Ph
Ph
Et
Me CH3(CH2)4 CO2Me
Me Me3Si
Me Me
Me Ph
CO2Et
CO2Me
CO2Et
Bu CH3(CH2)4 CO2Me
a) The reaction was carried out in toluene (0.3 mL in entries 1–4, 0.4 mL in entries 5–9) using
an acylstannane (0.46 mmol in entries 1–4, 0.30 mmol in entries 5–9), an alkyne (0.69 mmol
in entries 1–4, 0.90 mmol in entries 5–9) and Ni(cod)2 (0.23 µmol in entries 1–4, 0.15 µmol
in entries 5–9). b) Isolated yield based on the acylstannane. c) Determined by 119Sn NMR.
fect. The α-selection should imply the possibility that the
1-4. Carbostannylation of Arynes.21 The carbostannyla-
tion of benzyne (1,2-didehydrobenzene) prepared in situ from
2-(trimethylsilyl)phenyl triflate (trifluoromethanesulfonate)
(22a) and CsF was found to be catalyzed by a palladium–imi-
nophosphine complex as shown in Eq. 8 and Table 5. Imino-
phosphine IP having a 2-phenylethyl group on the nitrogen
atom is more effective than other iminophosphines (IP(Cy),
IP(Ph)) or other phosphine ligands. In addition to alkynyl-
stannanes, tributyl(vinyl)tin that was unreactive towards
alkynes under similar conditions, successfully reacted with
benzyne.
nickel-catalyzed allylstannylation proceeds through a catalytic
cycle similar to Cycle D in Scheme 5, which is initiated by ox-
idative addition of an allylstannane to a palladium(0) complex.
1-3. Acylstannylation.20,16b Ni(cod)2 was demonstrated to
be effective also for acylstannylation of alkynes, which gives
β-stannylenones and related compounds (Eq. 7 and Table 4).
Use of a more polar solvent than toluene or a phosphine as a
ligand caused decarbonylation from acylstannanes and the
yields of the carbostannylation products decreased obviously.
(8)
(7)
Table 5. Carbostannylation of Benzynea)
The first step of the catalytic cycle should be, we consider,
oxidative addition of an acylstannane to the nickel(0) complex.
Although we have not observed the formation of the oxidative
adduct, the fact that trimethyl(phenyl)tin is generated through
decarbonylation probably from the oxidative adduct in the
nickel-catalyzed reaction of benzoyl(trimethyl)tin (19a) in the
absence of an alkyne (Scheme 8) should demonstrate the abili-
ty of acylstannanes to oxidatively add to nickel(0) complexes.
Then, insertion of an alkyne to the carbon–nickel or tin–nickel
bond followed by reductive elimination should take place to
give acylstannylation products.
Entry
R
Time/h
Yield/%b)
1
2
3
4
5
PhCWC
t-BuCWC
BuCWC
MeCWC
MeOCH2CWC
MeC(wCH2)CWC
1-cyclohexenyl-CWC
CH2wCH
3
8
4
0.5
2.5
2
1.5
25
54
53
41
30
51
51
35
47
6
7
8c)
a) The reaction was carried out in MeCN (3 mL) at 50 °C
using an organostannane (0.34 mmol), 2-(trimethylsil-
yl)phenyl triflate (0.69 mmol) and CsF (0.69 mmol) in the
presence of [PdCl(η3-C3H5)]2 (8.2 µmol) and IP (16 µmol).
b) Isolated yield based on the organostannane. c) An
increased amount of benzyne precursors, 2-(trimethylsil-
yl)phenyl triflate (1.4 mmol) and CsF (1.4 mmol), was
used.
The carbostannylation was also applicable to substituted
benzynes (Scheme 9). The fact that both 4-methyl- and 5-
methylbenzyne precursors (22b and 22c) gave regioisomeric
products in similar ratios and yields indicates that the common
intermediate 4-methylbenzyne must be involved in both reac-
tions.
Scheme 8.

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1441
present carbostannylation. Alternatively, the palladium(0)–IP
complex might undergo oxidative cyclization with an aryne to
form a palladacyclopropene (Cycle F),22 which then reacts
with an organostannane (Section 3).
2. Carbostannylation of Dienes
In contrast to the carbometalation of alkynes, the addition of
carbon–metal bonds of organometallic compounds to dienes is
extremely rare,23,24 although it would provide synthetically
useful alkenyl- or allylmetal reagents. Since we had discov-
ered the carbostannylation of alkynes using organostannanes
of adequate reactivity, we then studied the carbostannylation of
dienes.25,26 Our activation method (Type i in Scheme 1) that
includes oxidative addition of a carbon–tin bond to a nickel(0)
complex mentioned in the introductory section was found to be
effective also for the carbostannylations of 1,3- and 1,2-dienes,
whereas palladium complexes did not show sufficient catalytic
activity in the addition of organostannanes to dienes.
2-1. Acylstannylation of 1,3-Dienes.27
Acylstannylation
of 1,3-dienes proceeded under the conditions for the acylstan-
nylation of alkynes (Ni(cod)2, no ligand, toluene, Section 1-3)
but at lower temperatures (Eq. 9 and Table 6). Carbon–tin
bonds in aromatic and aliphatic acylstannanes in addition to an
aminocarbonylstannane reacted exclusively in a 1,4-manner
with complete syn-selectivity except for the case of the ami-
nocarbonylstannane. The reaction is applicable to various 2-
substituted and 2,3-disubstituted 1,3-dienes but not to any 1-
substituted ones. The regioselectivity in the reaction of un-
symmetrical 1,3-dienes was at best 1:2 (entries 5–8).
Scheme 9.
(9)
Scheme 10.
Two plausible catalytic cycles for this reaction are shown in
Scheme 10. Cycle E, which is familiar to us, is possible but is
rather improbable, because there have been no signs of oxida-
tive addition of alkenylstannanes, which can participate in the
The catalytic cycle here also should be similar to the nickel-
catalyzed acylstannylation of alkynes, starting with oxidative
addition of an acylstannane to a nickel(0) complex. A 1,3-di-
Table 6. Acylstannylation of 1,3-Dienesa)
Entry
R1
R2
R3
R4
Time/h
Yield/%b)
24:25c)
1
2
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Me
Me
Me
Me
Me
Me
Me
Me
Bu
H
Me
Ph
–(CH2)4–
Me
H
Me
Ph
0.2
2
48
24
2
2
2
2
24
2
72
73
36
45
74
68
84
86
56
52
73f)
—
—
—
3d)
4e)
5
—
H
H
H
H
Me
Me
Me
33:67
47:53
44:56
39:61
—
6
7
8
Ph
SiMe3
CH2SiMe3
Me
Me
Me
9e)
10e)
11
Et
Me2CwCH
(CH2)5N
Bu
Bu
—
—
2
a) The reaction was carried out in toluene (0.3 mL) at 50 °C using an acylstannane (0.23
mmol), a 1,3-diene (0.69 mmol), and Ni(cod)2 (11.5 µmol). b) Isolated yield based on
the acylstannane. c) Determined by 119Sn NMR. d) The reaction was carried out at 80
°C. e) The reaction was carried out at 70 °C. f) A 87:13 mixture of (Z)- and (E)-iso-
mers was obtained.

1442 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Table 7. Acylstannylation of 1,2-Dienesa)
Entry R1
R2
R3
H
Time/h Yield/%b)
1c)
2
3
4
5
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Et
Me
Me Bu
Me t-Bu
Me 4-MeOC6H4
Me Ph
Me 4-CF3C6H4
Me MeO
Bu
Bu
Bu Bu
Bu Ph
Bu MeO
1.5
1.5
1.5
2
64
79
59
50
53
35
26
48
67
53
43
48
25
2
2
2
4
6
7
8c)
9c)
10d)
11d)
12d)
H
H
1.5
2
Et
Et
Et
Scheme 11.
3.5
2.5
2
13c),e) (CH2)5N Me
H
ene would then insert into the carbon–nickel bond (carbonick-
elation) or the tin–nickel bond (stannylnickelation) of the re-
sulting oxidative adduct (26) to give a π-allylnickel complex
27;28 the following reductive elimination could give acylstan-
nylation product 24 and regenerate the nickel(0) complex.
Worthy to note is that the stereochemical outcome depends on
the R1 moiety of acylstannanes, namely benzoylstannane af-
fords syn-adduct as a sole product and aminocarbonylstannane
gives a mixture of syn- and anti-adducts. This fact may imply
that the stannylnickelation pathway shown in Scheme 11 is
more plausible than the carbonickelation pathway, and isomer-
ization of anti-π-allylnickel 27 (R1 = (CH2)5N) to syn-isomer
27ꢀ before reductive elimination may be responsible for the co-
production of (E)-isomer of 24. The aminocarbonyl group ap-
pears to retard the reductive elimination leading to 24.
a) The reaction was carried out in toluene (0.4 mL) at 50 °C
using an acylstannane (0.30 mmol), a 1,2-diene (0.90
mmol), and Ni(cod)2 (15 µmol). b) Isolated yield based on
the acylstannane. c) The reaction was carried out under an
allene atmosphere (1 atm). d) The reaction was carried out
at 80 °C. e) The reaction was carried out at 100 °C in the
presence of 60 µmol of Ni(cod)2.
plausible. Namely, stannylnickelation might proceed in pref-
erence to acylnickelation.
(11)
2-2. Acylstannylation of 1,2-Dienes.29 The methodology
can be extended to acylstannylation of 1,2-dienes, which gives
α-(acylmethyl)vinylstannanes as the major products through
the addition of carbon–tin bonds to internal double bonds of
1,2-dienes (Eq. 10). This type of alkenylstannanes30 having an
exomethylene group is inaccessible by the standard carbostan-
nylation of alkynes. Under the conditions similar to the acyl-
stannylation of 1,3-dienes, various alkyl-, aryl-, and methoxy-
allenes undergo acylstannylation with aromatic and aliphatic
acylstannanes as summarized in Table 7.
(12)
(10)
Disubstituted allenes also participated in the acylstannyla-
tion. Addition of carbon–tin bonds takes place preferentially
at the internal double bond of the 1,1-disubstituted allene in
Eq. 11 as is the case with the reaction of monosubstituted al-
lenes. The fact that the reaction of the 1,3-disubstituted allene
in Eq. 12 with acylstannanes gave mixtures of stereoisomers
gives us a key to solve the reaction mechanism. Oxidative ad-
dition of an acylstannane to the nickel(0) complex must initiate
the catalytic cycle, which should be followed by either stan-
nylnickelation or acylnickelation. The catalytic cycles exem-
plified by the reaction of 4,5-nonadiene are shown in Scheme
12. If acylnickelation would take proceed with Cycle H, (E)-
alkenylstannanes should be obtained at least as major products
(discrimination between H and Pr) through stereo-retained re-
ductive elimination from (E)-alkenylnickel complexes 31.31
As the isomeric ratios are close to 1:1, Cycle G appears to be
Scheme 12.
2-3. Alkynylstannylation of 1,2-Dienes.32 The reaction
conditions of the acylstannylation of 1,3- and 1,2-dienes
turned out to be futile for the corresponding alkynylstannyla-
tion as they stand. After a thorough search for better reaction
conditions, we found that alkynylstannylation of 1,2-dienes

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1443
Table 8. Alkynylstannylation of 1,2-Dienesa)
Entry
Ligand R1
R2
Temp/°C
Time/h
Yield/%b)
33:34c)
1
2d)
3
4
5
6
7
8
9
10
11d)
12
13
DPPP
Ph
Ph
Ph
Ph
Bu
Bu
H
t-Bu
MeO
Bu
Bu
H
30
60
30
50
0
30
30
50
50
30
60
50
50
10
40
10
70
23
5
72
70
63
57
53
92
52
91
90
82
70e)
67
81e)
85:15
87:13
—
98:2
28:72
87:13
77:23
—
Ph
4-CF3C6H4
4-MeOC6H4
Me3Si
Et3Si
72
7
H
24
10
46
49
26
—
DMPP Ph
Bu
Bu
t-Bu
Bu
32:68
37:63
14:86
37:63
Ph
Ph
Me3Si
a) The reaction was carried out in toluene (0.3 mL) using an alkynylstannane (0.20
mmol), a 1,2-diene (0.60 mmol in entries 1–9, 0.30 mmol in entries 10–13) in the pres-
ence of Ni(cod)2 (10 µmol) and a bisphosphine ligand (10 µmol). b) Isolated yield
based on the alkynylstannane. c) Determined by 119Sn NMR. d) Tributyl(phenylethy-
nyl)tin was used instead of the trimethylstannyl analogue. e) Determined by 119Sn
NMR using Bu4Sn (entry 11) or Me4Sn (entry 13) as an internal standard.
took place in the presence of a catalytic amount of a nickel(0)
complex coordinated by a 1,3-diphosphinopropane ligand.
Other mono- and bisphosphine ligands such as triphenylphos-
phine, 1,4-bis(diphenylphosphino)butane, and IP gave only
complex mixtures of products. The substituents on phospho-
rous of the bisphosphine ligands affected markedly the selec-
tion of allene double bonds: a Ni–DPPP catalyst favored the
internal double bond of allene to give addition products 33
predominantly, whereas 1,3-bis(dimethylphosphino)propane
(DMPP) preferred to react at the terminal double bonds and 34
were obtained as major products (Eq. 13). Results using aryl-
and silylethynylstannanes, various mono- or nonsubstituted al-
lenes, and DPPP or DMPP ligand are summarized in Table 8.
All of alkenylstannanes 34 in Table 8 have (Z)-configuration.
of the reaction. An alternative carbonickelation pathway ap-
pears improbable, because it should give 34ꢀ at least as major
products via alkenylnickel 40 as mentioned in the previous
section.
(14)
(15)
(13)
The preference of Ni–DPPP for the internal double bonds
also was observed in the addition of a phenylethynylstannane
to a 1,1-disubstituted allene (Eq. 14). In contrast to the acyl-
stannylation mentioned above, the reaction of a 1,3-disubstitut-
ed allene gave a single alkynylstannylation product having (Z)-
configuration (Eq. 15). On the basis of the stereochemistry ob-
served here, we consider the reaction mechanism depicted in
Scheme 13. Oxidative addition of an alkynylstannane to the
nickel(0) complex and subsequent insertion of the terminal
double bond of an allene through 36 into the tin–nickel bond
provides β-stannyl-σ-allylnickel 37. After isomerization of 37
to π-allylnickel complex 38 and then to 39, reductive elimina-
tion at C-1 and/or C-3 of the allyl moiety should afford alky-
nylstannylation product 33 and/or 34, respectively, although it
is not clear how ligand DPPP or DMPP determines the course
Scheme 13.
3. Dimerization–Carbostannylation of Alkynes33
As we disclosed in Section 1-1, the reaction of tributyl(phen-

1444 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Table 9. Dimerization–Carbostannylation of Alkynesa)
Entry Alkyne
R
Ligand
Temp/°C Time/h Yield/%b) 41:42:43c)
1
2
3
4
5
6
7
8
9
10
11
12
13
14d)
15d)
16
17
18
19
20
21
22
23
24
4b
PhCWC
BuCWC
NN
NN
NN
NN
NN(i-Pr)
NN
NN
NN
NN(i-Pr)
NN
NN(i-Pr)
NN(i-Pr)
NN(i-Pr)
NN(i-Pr)
NN(i-Pr)
NN
NN
NN
NN
NN
50
30
20
50
50
50
50
50
50
50
50
50
50
50
50
70
90
90
50
50
50
50
50
20
0.7
3
0.5
0.7
1
77
93
75
72
78
76
78
81
78
42
68
80
79
42
64
77
32
52
76
75
75
63
75
86e)
100:0:0
100:0:0
100:0:0
79:21:0
100:0:0
89:11:0
71:29:0
30:63:7
100:0:0
13:69:18
100:0:0
100:0:0
100:0:0
100:0:0
100:0:0
—
Me3SiCWC
CH2wCH
CH2wCH
(E)-PhCHwCH
(E)-HexCHwCH
2-furyl
2-furyl
2-thienyl
2-thienyl
3-thienyl
14
40
14
13
12
22
21
23
27
19
2
19
2
2
1
8
2-benzofuryl
Ph
4-MeOC6H4
PhCWC
4a
BuCWC
—
—
—
—
—
—
—
—
Me3SiCWC
CH2wCH
(E)-PhCHwCH
(E)-HexCHwCH
2-furyl
NN
NN
NN
19
26
1
2-benzofuryl
(E)-PhCHwCHCH2 NN
a) The reaction was carried out in toluene (3 mL) using an organostannane (0.34 mmol) and an
alkyne (1.0 mmol) in the presence of [PdCl(η3-C3H5)]2 (8.2 µmol) and NN or NN(i-Pr) (16 µmol).
b) Isolated yield based on the organostannane. c) Determined by 119Sn NMR. d) An aryl(tri-
methyl)tin was used instead of the tributylstannyl analogue. e) A 1:1 adduct was also obtained in
4% yield.
ylethynyl)tin (1a) with ethyl propiolate (4b) catalyzed by a
(E)-1,2-bis(tributylstannyl)ethene, six new covalent bonds be-
ing generated all at once to give α,ω-bisstannyldecapentaenes
(Eq. 17).
palladium complex coordinated by IP or its derivative gives
1:1 adducts as a mixture of regioisomers. In contrast, use of
1,2-bis(phenylimino)acenaphthene (NN) as a ligand in lieu of
the iminophosphine completely changed the reaction course;
alkynylstannylation of 4b was accompanied by dimerization of
4b to afford (1Z,3E)-6-phenyl-1-tributylstannylhexa-1,3-dien-
5-yne-1,4-dicarboxylate (41a) (Eq. 16). To the best of our
knowledge, this is the first demonstration of dimerization–car-
bometalation of alkynes. Not only alkynylstannanes but also
alkenyl-, allyl-, and arylstannanes are applicable to the reaction,
giving conjugated alkynyldienylstannanes, trienylstannanes,
and aryldienylstannanes, respectively (Table 9, entries 1–15).
Although organostannanes other than alkynylstannanes gave
dimerization–carbostannylation products as mixtures of regioi-
somers 41, 42, and 43 under the conditions, use of bulkier
ligand NN(i-Pr) much improved the selectivity as was the case
for the ligand effect in the palladium-catalyzed alkynylstanny-
lation of alkynes described in Section 1-1, and 41 were pro-
duced as the sole products. We will discuss the ligand effect
later in the context of reaction mechanism. Dimethyl acetyl-
enedicarboxylate (4a) also reacts with organostannanes in the
presence of the Pd–NN catalyst to give single isomers (Table
9, entries 16–24), although other alkynes such as phenylacetyl-
ene, 1-octyne, and 3-butyn-2-one cannot participate in the
dimerization–carbostannylation. Noteworthy is that a highly
conjugated π-system is readily constructed by the reaction of
(16)
(17)

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1445
Fig. 1. 1H NMR (200 MHz) spectrum of the reaction mix-
ture (at ca. 31% conversion) in the reaction of 45 with 4a
in the presence of [PdCl(η3-C3H5)]2–NN(p-tol) complex
(20 mol% of Pd, Pd/NN(p-tol) = 1) in CDCl3 at 25 ˚C.
Since the present dimerization–carbostannylation of alkynes
is not accompanied by 1:1 carbostannylation products nor by
trimerization–carbostannylation products, the reaction is un-
likely to proceed through a catalytic cycle similar to those of
the carbostannylations of alkynes (Section 1): oxidative addi-
tion, insertion, and reductive elimination. Since it is well-doc-
umented that palladacyclopentadiene 44b is formed through
the oxidative cyclization of two molecules of 4a with palladi-
um–diimine complexes, is well-documented,34 we considered
that palladacyclopentadienes should be involved in the reac-
Scheme 14.
46a being thermodynamically stable and 46b kinetically fa-
vored. Isopropyl groups on NN(i-Pr) block the apical position
of palladium complex 4635 and thus retard the reaction with or-
ganostannanes to allow palladacyclopentadiene 46b to isomer-
ize to 46a. This then reacts with organostannanes to give ex-
clusively dimerization–carbostannylation product 41.
1
tion. In fact, we monitored the reaction by H NMR using
bis(p-tolylimine) NN(p-tol) ligand to find that the spectra of
the reaction of tributyl(vinyl)tin (45) with 4a showed, in addi-
tion to those of the substrates and the dimerization–carbostan-
nylation products, no peaks other than those of palladacycle
44a (Fig. 1). Furthermore, the reaction of palladacyclopenta-
diene 44b with 45 gave dimerization–carbostannylation prod-
uct 41b in a reasonable yield (Eq. 18), and 44b was shown to
be an equally active catalyst (Eq. 19). All these observations
suggest the involvement of the palladacyclopentadiene inter-
mediates.
4. Synthetic Applications of the Carbostannylation Prod-
ucts
From the viewpoint of synthetic reagent, in sharp contrast to
other organometallic compounds, organostannanes achieve an
exquisite balance between stability and reactivity. They are
storable at room temperature, usually being prepared and puri-
fied step by step prior to use. Meanwhile, the reagents have
sufficient reactivity to attain carbon–carbon bond formation
chemoselectively with the aid of an appropriate activator such
as a palladium catalyst or a Lewis acid. The transformation
methods are applicable also to the present carbostannylation
products having certain functional groups. In this Section, we
demonstrate the synthetic versatility by transformation to vari-
ous compounds that possess complicated structures through
cross-coupling reactions, homocoupling reactions and Lewis
acid-mediated reactions with carbonyl and related compounds.
4-1. Cross-Coupling Reaction. The alkynyl- or acylstan-
nylation of alkynes gives alkenylstannanes having a conjugat-
ed alkynyl or acyl group, respectively. Their π-conjugation
can be easily extended by conversion of their stannyl group to
an organic group having π-bonds through the cross-coupling
reaction with organic electrophiles (Scheme 15). For example,
alkynylstannylation product 5a was transformed to enediyne
47 or arylenyne 48,13 whereas β-aryl enone 49 was obtained
from β-stannyl enone 20a. The reaction with an allylic elec-
trophile also proceeded to give partially conjugated dienone
50. Highly conjugated systems can be obtained simply from
(18)
(19)
The perfect regioselectivity in the reaction of ethyl propi-
olate (4b) brought by introduction of a bulky substituent into
the phenyl rings of diimine NN may be explained as follows
(Scheme 14). There would be an equilibrium between pallada-
cycle 46a and 46b through a palladium(0)–diimine complex,

1446 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Scheme 15.
Scheme 17.
nylation product 33a of allene. The cross-coupling reaction of
allene-acylstannylation product 29a with an aryl iodide also
proceeded to give β-aryl-β,γ-unsaturated ketone 59, which can
be converted to conjugated β-aryl (E)-enone 60 through base-
catalyzed isomerization of the carbon–carbon double bond
(Scheme 18). Change of the order of the sequence (isomeriza-
tion before cross-coupling) afforded the corresponding (Z)-iso-
mer (61). Another β-aryl-β,γ-unsaturated ketone (62) is avail-
able through dimethylation of 29a followed by cross-coupling
with the aryl iodide. The cross-coupling of 29a with benzoyl
chloride provided exomethylene type enedione 63.
4-2. Homocoupling Reaction followed by Annulations.
A wide variety of polycyclic compounds can be prepared from
the alkynylstannylation products of 1,2-dienes through homo-
coupling as a key reaction. Examples are summarized in
Scheme 19. α-(Alkynylmethyl)vinylstannane 33b homo-
coupled37 in the presence of a palladium catalyst and cop-
per(ꢀ)/(Ⅱ) reagents to give symmetrical dienyldiyne 64, which
was desilylated with TBAF. The resulting dimethylenediyne
65 underwent two different modes of cyclization: annulation
through the Diels–Alder reaction of the diene moiety and dou-
ble annulation through nickel-catalyzed reaction of the diyne
moiety with acetylene,38 to give tricyclic compound 66. Diels–
Alder reaction of dienyldiyne 67, the homocoupling product of
33a, gave 68, which was transformed to tetracyclic compound
69 through zirconocene-mediated reaction with o-diiodoben-
zene.39 Alternatively, 67 was first converted by zirconocene-
mediated cyclization to tetraene 70, which underwent a double
Scheme 16.
the dimerization–carbostannylation products. Thus, stannyl
dienyne 41a was coupled with 1-iodo-4-nitrobenzene, bro-
moacetylene, and 1,4-diiodobenzene to give 51–53 (Scheme
16).36
The cross-coupling reaction of allylstannylation product
10a with an allyl carbonate provides triene 54, whereas cou-
pling of 10a with an aryl iodide in the presence of 10 mol% of
Pd(PPh3)4 gave partially conjugated aryldiene 55 (Scheme 17).
Conjugated ethenes 56–58 can be obtained from alkynylstan-

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1447
Diels–Alder reaction with diethyl acetylenedicarboxylate to
afford tricyclic compound 71.
Like the cross-coupling in the previous section, π-conjuga-
tion of dimerization–carbostannylation product 41b can be ex-
tended to tetraene 72 by a copper(Ⅱ)-mediated homocoupling
reaction (Eq. 20).
(20)
4-3. Reaction with Carbonyl Groups. As we disclosed
in Section 2-1, the nickel-catalyzed acylstannylation of 1,3-
dienes provides ε-oxo 2-alkenylstannanes, which are not easily
available by other methods because of the reactive carbonyl
functionality. The carbonyl group in the allylstannanes was
found to assist regioselective addition to aldehydes (Eq. 21 and
(21)
Table 10). Allylstannane 24a (R1 = Ph) derived from benzoyl-
stannane and 1,3-butadiene underwent the Bu2SnCl2-mediated
reaction with aldehydes to give exclusively α-adduct 73 in
sharp contrast to unfunctionalized tributyl(crotyl)stannane,
which affords regioisomeric mixtures.40 The exclusive α-se-
lectivity should be ascribed to intramolecular coordination
Scheme 18.
Scheme 19.

1448 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
a)
Table 10. Addition of Allylstannanes to Aldehydes Mediated by Bu2SnCl2
Entry R1
R2
R3
Config. of 24 R4
Time/h Yield/%b)
E:Z
1
2
3
4
Ph
Ph
Me
Me
H
H
Z
Z
Z
E
i-Pr
3.5
3.5
2.0
2.0
67
76
98
87:13
89:11
> 99:1
> 99:1
Phc)
i-Pr
i-Pr
(CH2)5N Bu Me
(CH2)5N Bu Me
100
a) The reaction was carried out at room temperature using an allylstannane (0.30 mmol),
an aldehyde (0.60 mmol) and Bu2SnCl2 (0.36 mmol). b) Isolated yield based on the allyl-
stannane. c) Benzaldehyde (0.36 mmol) was used.
(74) of the carbonyl group to the tin atom to induce the car-
Grants-in-Aid for COE Research on Elements Science, No.
12CE2005 and Scientific Research, No.12750758 from the
Ministry of Education, Science, Sports and Culture. E.S.
thanks the Asahi Glass Foundation for financial support.
bon–carbon bond formation at the terminal carbon. Perfect re-
gioselectivity was observed also in the Bu2SnCl2-catalyzed re-
action of allylstannane 24b with acyl chlorides, the carbon–
carbon bond being generated exclusively at the γ-carbon of the
allylstannane (Eq. 22), whereas the corresponding reaction of
tributyl(crotyl)tin is less efficient in both yield and regioselec-
tivity.41 Acetals also are good electrophiles for the acylstanny-
lation products: allylstannane 24c reacts with BF3-activated
benzaldehyde dimethyl acetal to give γ-adducts 76 as a mixture
of diastereomers (Eq. 23).
References
1
a) M. Pereyre, J.-P. Quintard, and A. Rahm, “Tin in Organ-
ic Synthesis,” Butterworth, London (1987). b) A. G. Davies, “Or-
ganotin Chemistry,” VCH, Weinheim (1997).
2
a) J. K. Stille, Angew. Chem., Int. Ed. Engl., 25, 508
(1986). b) T. N. Mitchell, Synthesis, 1992, 803. c) V. Farina, in
“Comprehensive Organometallic Chemistry Ⅱ,” ed by E. W. Abel,
F. G. A. Stone, and G. Wilkinson, Pergamon Press, New York
(1995), Vol. 12, p. 200. d) V. Farina, V. Krishnamurthy, and W. J.
Scott, Org. React., 50, 1 (1997).
(22)
3
I. Fleming, in “Comprehensive Organic Synthesis,” ed by
B. M. Trost and I. Fleming, Pergamon Press, Oxford (1991), Vol.
2, p. 563.
4
Alkynylstannylation of dimethyl acetylenedicarboxylate
(23)
using (stannylethynyl)amines is reported: G. Himbert, J. Chem.
Res. Synop., 1979, 88.
5
Alkenylation of ketones or phenols using terminal alkynes
and SnCl4 is considered to proceed through carbostannylation of
stannylacetylenes: a) A. Hayashi, M. Yamaguchi, M. Hirama, C.
Kabuto, and M. Ueno, Chem. Lett., 1993, 1881. b) M. Yamaguchi,
A. Hayashi, and M. Hirama, J. Am. Chem. Soc., 115, 3362 (1993).
c) M. Yamaguchi, A. Hayashi, and M. Hirama, J. Am. Chem. Soc.,
117, 1151 (1995).
5. Conclusion
It has been disclosed that the carbostannylation of alkynes,
1,3-dienes, and 1,2-dienes using alkynyl-, allyl-, acyl-, alke-
nyl-, and arylstannanes proceeds efficiently using a palladium
or nickel catalyst with an appropriate ligand. In particular, bi-
dentate ligands like iminophosphine, diimine, and bisphos-
phine ligands are demonstrated to play critical roles in many
cases. Most of the carbostannylation reactions are based on
the activation of carbon–tin bonds through the oxidative addi-
tion to a palladium(0) or nickel(0) complex. This novel activa-
tion concept will be applied not only to the present reaction us-
ing other organostannanes but also to carbometalations in gen-
eral to assist us to design novel synthetic methodologies. The
mechanistic insight into the reaction through palladacyclopen-
tadienes (dimerization–carbostannylation of alkynes in Section
3) should provide us with a basis for the understanding of sim-
ilar reactions of metallacycles and should definitely contribute
to the development of new dimerization–carbometalation reac-
tions of unsaturated compounds.
6
Stepwise carbostannylation of alkynes may be accom-
plished by carbocupration of alkynes followed by quenching with
tin halides or triflates: H. Westmijize, J. Meijer, and P. Vermeer,
Recl. Trav. Chim. Pays-Bas, 96, 194 (1977).
7
N. Asao and Y. Yamamoto, Bull. Chem. Soc. Jpn., 73, 1071
(2000), and references cited therein.
a) K. Miura, T. Matsuda, T. Hondo, H. Ito, and A. Hosomi,
8
Synlett, 1996, 555. b) K. Miura, D. Itoh, T. Hondo, H. Saito, H.
Ito, and A. Hosomi, Tetrahedron Lett., 37, 8539 (1996).
9
We reported that the palladium complex coordinated by IP
is an efficient catalyst for the Kosugi–Migita–Stille reaction: E.
Shirakawa, H. Yoshida, and H. Takaya, Tetrahedron Lett., 38,
3759 (1997).
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11 We have reported an account concerning the palladium–
iminophosphine-catalyzed reactions of organostannanes including
the cross-coupling reaction and alkynylstannylation of alkynes: E.
Shirakawa and T. Hiyama, J. Organomet. Chem., 576, 169 (1999),
or in “Perspectives in Organopalladium Chemistry for the ꢁꢁꢀ
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We are indebted to our collaborators for their devotion to
our chemistry: Dr. H. Yoshida, K. Yamasaki, Y. Nakao, T.
Kurahashi, and Y. Honda at Kyoto University, and Dr. T.
Tsuchimoto and Y. Yamamoto at Japan Advanced Institute of
Science and Technology. This research was supported by

E. Shirakawa et al.
Bull. Chem. Soc. Jpn., 75, No. 7 (2002) 1449
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27 E. Shirakawa, Y. Nakao, H. Yoshida, and T. Hiyama, J. Am.
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13 V. Farina and B. Krishnan, J. Am. Chem. Soc., 113, 9585
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14 Oxidative addition of an allylstannane to a palladium(0)
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T. Hiyama, Chem. Commun., 2001, 1926.
28 A similar catalytic cycle involving an anti-π-allylplatinum
intermediate generated by insertion of a 1,3-diene to a Pt–B bond
is proposed in the platinum-catalyzed diboration of 1,3-dienes: T.
Ishiyama, M. Yamamoto, and N. Miyaura, Chem. Commun., 1996,
2073.
29 E. Shirakawa, Y. Nakao, and T. Hiyama, Chem. Commun.,
2001, 263.
30 Vinylstannanes having an α-substituent are available by
stannylcupration of alkynes followed by quenching the resulting
C–Cu bond with methanol: J. A. Carbezas and A. C. Oehlschlager,
Synthesis, 1994, 432.
31 Platinum-catalyzed diboration of monosubstituted allenes,
which is considered to proceed via an alkenylplatinum complex
similar to 31, and gives (Z)-isomer stereoselectively. T. Ishiyama,
T. Kitano, and N. Miyaura, Tetrahedron Lett., 39, 2357 (1998).
32 E. Shirakawa, Y. Nakao, T. Tsuchimoto, and T. Hiyama,
submitted for publication.
33 a) E. Shirakawa, H. Yoshida, Y. Nakao, and T. Hiyama, J.
Am. Chem. Soc., 121, 4290 (1999). b) H. Yoshida, E. Shirakawa,
Y. Nakao, Y. Honda, and T. Hiyama, Bull. Chem. Soc. Jpn., 74,
637 (2001).
34 Elsevier and his co-workers reported a three component
coupling of acetylenedicarboxylates, organic halides, and alkynyl-
stannanes, using the palladium–NN complex as a catalyst; the cat-
alytic cycle is considered to involve a reaction of palladacyclopen-
tadiene 44b derived from Pd(0)–NN and 4a. Subsequent reaction
with an organic halide followed by transmetalation with an orga-
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1450 Bull. Chem. Soc. Jpn., 75, No. 7 (2002)
ACCOUNTS
Eiji Shirakawa was born in Takarazuka, Japan, in 1964. He graduated, with his MS degree,
from Kyoto University in 1989 and then joined Pharmaceutical Research Institute, Japan
Tobacco Inc. In 1995 he was appointed as an Instructor of Department of Material Chemis-
try, Kyoto University, and received his Ph.D. degree there in 1997. In 1998 he was promoted
to Associate Professor at Japan Advanced Institute of Science and Technology. His research
interest lies in the development of new synthetic methodologies with newly designed transi-
tion metal catalysts. In particular, his present concern is the transition metal-catalyzed new
addition reactions between relatively unreactive compounds.
Tamejiro Hiyama is Professor of Graduate School of Engineering, Kyoto University. He
was born in 1946, Osaka, started his academic career in 1972 as a Research Associate at
Kyoto University, received the Doctor of Engineering degree in 1975 from Kyoto University,
and spent a postdoctoral year at Harvard University. In 1981, he joined Sagami Chemical
Research Center as Research Fellow, a group leader. There he was promoted to Senior Re-
search Fellow and then to Executive Research Fellow. In 1992, he moved to Research Labo-
ratory of Resources Utilization, Tokyo Institute of Technology, as Professor of Division of
Newer Metal Resources. Since 1997, he has been back at Kyoto University as Professor of
Organic Material Chemistry. He is a recipient of the Young Chemist Award of the Chemical
Society of Japan, 1980. His research interest extends to new organometallic reagents for se-
lective organic synthesis, organofluorine and organosilicon chemistry, synthesis of biologi-
cally active substances, design and synthesis of novel functionality molecules and materials.