Palladium-iminophosphine-catalyzed alkynylstannylation of alkynes

Article abstract of DOI:10.1021/om000828u

A palladium complex coordinated by an iminophosphine ligand was found to catalyze the addition of alkynylstannanes to a carbon - carbon triple bond of various alkynes in moderate to good yields with exclusive syn selectivity. The alkynyl group in the stannanes was attached mainly to the internal carbon of terminal alkynes, except for 1-alkyn-3-ones and alkynoates, where the alkynyl group was connected to the terminal carbon. Steric bulk of the ligand markedly influenced on the regioselectivity and reaction rate: an iminophosphine with a bulkier imino moiety accelerated the alkynylstannylation with higher regioselectivity. On the basis of these observations, the mechanism of the present reaction is discussed.

Full text of DOI:10.1021/om000828u

Organometallics 2000, 19, 5671-5678
5671
P a lla d iu m -Im in op h osp h in e-Ca ta lyzed
Alk yn ylsta n n yla tion of Alk yn es
Hiroto Yoshida,† Eiji Shirakawa,*,‡ Takuya Kurahashi,† Yoshiaki Nakao,† and
Tamejiro Hiyama*,†
Department of Material Chemistry, Graduate School of Engineering, Kyoto University,
Sakyo-ku, Kyoto 606-8501, J apan, and Graduate School of Materials Science,
J apan Advanced Institute of Science and Technology, Asahidai, Tatsunokuchi,
Ishikawa 923-1292, J apan
Received September 25, 2000
A palladium complex coordinated by an iminophosphine ligand was found to catalyze the
addition of alkynylstannanes to a carbon-carbon triple bond of various alkynes in moderate
to good yields with exclusive syn selectivity. The alkynyl group in the stannanes was attached
mainly to the internal carbon of terminal alkynes, except for 1-alkyn-3-ones and alkynoates,
where the alkynyl group was connected to the terminal carbon. Steric bulk of the ligand
markedly influenced on the regioselectivity and reaction rate: an iminophosphine with a
bulkier imino moiety accelerated the alkynylstannylation with higher regioselectivity. On
the basis of these observations, the mechanism of the present reaction is discussed.
Sch em e 1
In tr od u ction
Carbometalation of alkynes is one of the most useful
reactions for stereoselective olefin synthesis, since the
resulting alkenylmetals can be transformed further to
variously substituted ethenes.1 In particular, carbocu-
pration,2 zirconium-catalyzed carboalumination,3 and
nickel-catalyzed carbozincation4 have high synthetic
potential due to wide applicability (Scheme 1). However,
most of the organometallic compounds which undergo
addition to a triple bond of alkynes have relatively polar
C-M bonds and the corresponding carbometalation
products also have high reactivities to be trapped by
suitable electrophiles in situ.
On the other hand, carbostannylation of alkynes
should be much more beneficial in view of the stereo-
and regio-defined synthesis of multisubstituted ethenes,
because the resulting alkenylstannanes are easily puri-
fied in a separate step prior to such a subsequent
transformation as the Stille-Migita-Kosugi coupling
reaction.5 Furthermore, high chemoselectivity of orga-
nostannanes should make the carbostannylation and
subsequent reactions applicable to a wide variety of
substrates. There have been, however, a limited number
of reports on the carbostannylation of alkynes, probably
due to low polarity of a C-Sn bond.6-8 Yamamoto and
co-workers9 have reported that allylstannanes add to
terminal alkynes with anti selectivity using a Lewis acid
catalyst. Anti selective allylstannylation of alkynes is
found also by Hosomi and co-workers10 to be mediated
by a radical initiator, AIBN. In both cases, the scope is
limited solely to allylic stannanes.
We have already disclosed11 that tributyl(phenyleth-
ynyl)tin (2a ) adds oxidatively to a palladium(0) complex
coordinated by N-[2-(diphenylphosphino)benzylidene]-
2-phenylethylamine (1a ) to give nucleophilic palladium-
(II) complex 3a , which is involved in the catalytic cycle
of palladium-catalyzed cross-coupling of 2a with aryl
iodides (Scheme 2). We envisaged that palladium com-
plex 3a would react with alkynes to give alkynylstan-
nylation products. This turned out to be the case.
We now report that a palladium-iminophosphine
complex catalyzes the addition of alkynylstannanes to
alkynes, leading to the regio- and stereoselective forma-
(7) Alkenylation of ketones or phenols by use of terminal alkynes
and SnCl4 is considered to proceed through carbostannylation of
stannylacetylenes. (a) Hayashi, A.; Yamaguchi, M.; Hirama, M.;
Kabuto, C.; Ueno, M. Chem. Lett. 1993, 1881-1884. (b) Yamaguchi,
M.; Hayashi, A.; Hirama, M. J . Am. Chem. Soc. 1993, 115, 3362-3363.
(c) Yamaguchi, M.; Hayashi, A.; Hirama, M. J . Am. Chem. Soc. 1995,
117, 1151-1152.
† Kyoto University.
‡ J apan Advanced Institute of Science and Technology.
(1) Knochel, P. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Semmelhack, M. F., Eds.; Pergamon Press: New York,
1991; Vol. 4, Chapter 4.4, pp 865-911.
(2) Normant, J . F.; Alexakis, A. Synthesis 1981, 841-870.
(3) (a) Negishi, E.; Takahashi, T. Synthesis 1988, 1-19. (b) van
Horn, D. E.; Negishi, E. Pure Appl. Chem. 1981, 53, 5333-5356.
(4) Stu¨demann, T.; Knochel, P. Angew. Chem., Int. Ed. Engl. 1997,
36, 93-95.
(5) (a) Pereyre, M.; Quintard, J .-P.; Rahm, A. Tin in Organic
Synthesis; Butterworth: London, 1987. (b) Davies, A. G. Organotin
Chemistry; VCH: Weinheim, Germany, 1997.
(8) Carbostannylation may alternatively be accomplished by car-
bocupration of alkynes followed by quenching with tin halides/
triflate: Westmijze, H.; Meijer, J .; Vermeer, P. Recl. Trav. Chim. Pays-
Bas 1977, 96, 194-196.
(9) Asao, N.; Matsukawa, Y.; Yamamoto, Y. Chem. Commun. 1996,
1513-1514.
(10) Miura, K.; Itoh, D.; Hondo, T.; Saito, H.; Ito, H.; Hosomi, A.
Tetrahedron Lett. 1996, 37, 8539-8542.
(6) Carbostannylation of alkynes by use of a combination of (stan-
nylethynyl)amines and dimethyl acetylenedicarboxylate: Himbert, G.
J . Chem. Res. (S) 1979, 88-89.
(11) Shirakawa, E.; Yoshida, H.; Hiyama, T. Tetrahedron Lett. 1997,
38, 5177-5180.
10.1021/om000828u CCC: $19.00 © 2000 American Chemical Society
Publication on Web 11/28/2000

5672 Organometallics, Vol. 19, No. 26, 2000
Yoshida et al.
Sch em e 2
Sch em e 4
Sch em e 3
Alk yn ylsta n n yla tion of Alk yn es Ca ta lyzed by
P d -1a . We first examined the reaction of alkynylstan-
nanes 2 with alkynes 4 in the presence of complex Pd-
1a and found that insertion of the carbon-carbon triple
bond of 4 between the C-Sn bond of 2 took place to
afford the corresponding conjugated (Z)-(stannyl)enynes
in good to high yields (Scheme 4, Table 1). Whereas 2a
reacted with acetylene (1 atm) in THF at 50 °C and gave
tributyl[(Z)-2-(phenylethynyl)ethenyl]tin (5a )17 in 81%
yield18 as a single isomer through exclusive syn addition
(entry 1), the use of triphenylphosphine (2 equiv to Pd)
or 1,3-bis(diphenylphosphino)propane in lieu of 1a
reduced the yield even after a prolonged reaction time
(48% yield, 43 h; 28% yield, 22 h). The alkynylstannyl-
ation was applied to propargyl ether 4b, which provided
5b and 6b in 67% yield with a ratio of 67:33 (entry 2).
In addition to 4b, propargylic amide 4c, imide 4d , and
arylacetylenes 4e and 4f reacted with 2a to give the
corresponding alkynylstannylation products (entries
3-6). The addition of 2a to ethoxyacetylene (4g) was
completed in 5 h, giving exclusively 5g (entry 7). Ethyl
2-butynoate (4h ) afforded 6h as the sole product, though
higher temperature and longer reaction time were
required (entry 8). The reaction of 2a with ethyl pro-
piolate (4i) gave alkynylstannylation products consisting
of regioisomers 5i and 6i in a 20:80 ratio (entry 9). A
ketonic acetylene, 3-butyn-2-one (4j), reacted with 2a
smoothly with regioselectivity similar to that of 4i (entry
10). Tributyl(1-hexyn-1-yl)tin (2b) also reacted with
alkyne 4a , 4e, or 4i, giving the corresponding alkenyl-
stannanes. The resulting regioselectivities were similar
to those with 2a (entries 11-13).19
tion of conjugated (stannyl)enynes.12-14 In particular,
a bulky ligand is found to improve both yields and
regioselectivities. The characteristic features of the
alkynylstannylation compared with other carbometa-
lation reactions are as follows: (1) Alkynyl moieties are
introduced into alkynes in a manner that can hardly
be achieved with an organometallic reagent having a
polar C-M bond. (2) To the best of our knowledge, the
present reaction is the first demonstration that carbo-
metalation should proceed through oxidative addition
of a C-M bond to a transition metal complex.
Resu lts a n d Discu ssion
Liga n d P r ep a r a tion . Iminophosphines 1a -1e were
prepared by condensation of 2-(diphenylphosphino)-
benzaldehyde15 with an appropriate amine in refluxing
toluene (Scheme 3). Similarly, 1f was prepared from
2-[bis(o-tolyl)phosphino]benzaldehyde, which was syn-
thesized from 2-(2-bromophenyl)-1,3-dioxolane and di-
ethyl chlorophosphonite as shown in Scheme 3.16
Ca ta lyst Im p r ovem en ts: 1. Liga n d Effect on
Regioselectivity a n d Rea ction Ra te. Although the
(12) A part of this work has been reported: Shirakawa, E.; Yoshida,
H.; Kurahashi, T.; Nakao, Y.; Hiyama, T. J . Am. Chem. Soc. 1998,
120, 2975-2976.
(13) (a) We also reported dimerization-carbostannylation of alkynes
catalyzed by a palladium-diimine complex: Shirakawa, E.; Yoshida,
H.; Nakao, Y.; Hiyama, T. J . Am. Chem. Soc. 1999, 121, 4290-4291.
(b) Nickel-catalyzed carbostannylation of alkynes wtih acyl, allyl and
alkynylstannanes: Shirakawa, E.; Yamasaki, K.; Yoshida, H.; Hiyama,
T. J . Am. Chem. Soc. 1999, 121, 10221-10222. (c) Palladium-catalyzed
allylstannylation of alkynes: Shirakawa, E.; Yoshida, H.; Nakao, Y.;
Hiyama, T. Org. Lett. 2000, 2, 2209-2211.
(14) Kosugi and co-workers reported palladium-catalyzed carbostan-
nylation of norbornene using organotin trichlorides: (a) Fugami, K.;
Enokido, T.; Kawata, K.; Kameyama, M.; Kosugi, M. Main Group Met.
Chem. 1999, 22, 511-514. (b) Fugami, K.; Mishiba, Y.; Hagiwara, S.;
Koyama, D.; Kameyama, M.; Kosugi, M. Synlett 2000, 553-555.
(15) Rauchfuss, T. B.; Wrobleski, D. A. Inorg. Synth. 1982, 21, 175-
179.
(16) (a) Burk, M. J .; Gross, M. F. Tetrahedron Lett. 1994, 35, 9363-
9366. (b) Oosterom, G. E.; van Haaren, R. J .; Reek, J . N. H.; Kamer,
P. C. J .; van Leeuwen, P. W. N. M. Chem. Commun. 1999, 1119-1120.
(17) Configuration of alkenylstannane 5a could not be determined
directly, because all of the olefinic protons of 5a appeared at the same
chemical shifts in 1H NMR. Z-Configuration of 5a was confirmed after
the transformation to the corresponding alkenyl iodide (11) by iodolysis
(Scheme 8). The coupling constant between olefinic protons of 11 was
8.3 Hz, which is typical of a cis-disubstituted ethylene. Iodolysis of R-
or â-(alkynyl)alkenylstannanes to the corresponding (alkynyl)alkenyl
iodides proceeds with retention of configuration: Stracker, E. C.;
Zweifel, G. Tetrahedron Lett. 1991, 32, 3329-3332.
(18) The yield based on alkynylstannane should be lower than 95%,
because 5% of alkynylstannane would be consumed for the reduction
of Pd(II) to Pd(0).

Alkynylstannylation of Alkynes
Organometallics, Vol. 19, No. 26, 2000 5673
Ta ble 1. P a lla d iu m -1a -Ca ta lyzed Alk yn ylsta n n yla tion of Alk yn esa
a
The reaction was carried out in THF (3 mL) at 50 °C with an alkynylstannane (0.34 mmol) and an alkyne (1.0 mmol) in the presence
of [PdCl(π-C3H5)]2 (8.2 µmol) and 1a (0.016 mmol). Combined isolated yields of 5 and 6 based on 2 are given. c Determined by 1H or
b
119Sn NMR. The reaction was carried out under an acetylene atmosphere (1 atm). e Ethoxyacetylene (0.34 mmol) was used. f Solvent )
d
dioxane, temperature ) 90 °C.
Pd-1a complex was applicable to the alkynylstannyla-
tion of various alkynes as described above, the regio-
selectivities and the reaction rates were not sufficient,
especially in the case of 4b. Therefore, we investigated
how a substituent on ligands would affect the regio-
selectivity and the reaction rate of the alkynylstannyl-
ation with 2a and 4b as model substrates (Scheme 5,
Table 2). The conversion of 2a and the ratio of alkynyl-
stannylation products 5 and 6 were monitored by 119Sn
NMR. When 2a was allowed to react with 4b in the
presence of Pd-1a in THF at 50 °C for 3 h, 5b and 6b
were produced in a ratio of 69:31 with 20% conversion
(entry 1). Use of iminophosphine ligand 1b derived from
cyclohexylamine accelerated the reaction considerably
with higher regioselectivity (entry 2). The regioselec-
(19) No other isomer than 5 and 6 was obtained out of the four
possible isomers in use of mono- or disubstituted alkynes. The
hydrolysis of the alkenylstannanes to the corresponding alkenes
revealed that the stannyl group in 5 had a proton at the geminal
position, whereas that in 6 had an R2 group. Syn addition in use of
acetylene led us to the conclusion that both 5 and 6 are also syn.

5674 Organometallics, Vol. 19, No. 26, 2000
Yoshida et al.
Ta ble 3. Alk yn ylsta n n yla tion of Alk yn es Ca ta lyzed
Sch em e 5
by P d -1b or P d -1ea
alkynyl-
entry stannane alkyne ligand (h)
time yieldb
ratio
(%) product(s) (5:6)c
1
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2b
2b
2b
4b
4a
4c
4d
4e
4f
4g
4h
4i
1b
1b
1b
1b
1b
1b
1b
1b
1e
1b
1b
1b
1e
5
1
3
3
5
6
5
93
1
1
81
70
71
77
73
70
58
29
71
83
88
86
62
5b, 6b
5a
5c, 6c
5d , 6d
5e
5f, 6f
5g
6h
79:21
2d
3
88:12
90:10
>99:1
97:3
4
5
6
7e
8f
9
>99:1
1:>99
7:93
5i, 6i
5j, 6j
5k
10
4j
13:87
11d
12
4a
4e
4i
2
12
24
5l
>99:1
13
5m , 6m
7:93
Ta ble 2. Alk yn ylsta n n yla tion of Alk yn es Ca ta lyzed
by P a lla d iu m -Im in op h osp h in e 1a
The reaction was carried out in THF (3 mL) at 50 °C with an
a
alkynylstannane (0.34 mmol) and an alkyne (1.0 mmol) in the
presence of [PdCl(π-C3H5)]2 (8.2 µmol) and iminophosphine (0.016
b
mmol). Isolated yields based on alkynylstannane are given.
1
d
c Determined by H or 119Sn NMR. The reaction was carried out
under an acetylene atmosphere (1 atm). e Ethoxyacetylene (0.34
mmol) was used. f Solvent ) dioxane, temperature ) 90 °C.
mized ligands (1b for alkynes 4a -h and 4j, 1e for
alkyne 4i). The results are summarized in Table 3.
Noteworthy is the high reaction rate: the alkynyl-
stannylation of 4b with Pd-1b was completed in 5 h
with a 79:21 ratio of 5b:6b, and the products were
isolated in 81% yield (entry 1; see also entry 2 of Table
1). Alkynes 4a and 4c-g were also reacted to give the
corresponding alkynylstannylation products in high
yields within 6 h with the regioselectivities over 88%
(entries 2-7). In contrast to the case of terminal
alkynes, the Pd-1b catalyst system did not promote the
reaction of internal alkyne 4h effectively, giving alkyn-
ylstannylation product 6h only in 29% yield (entry 8).
The reaction of alkyne 4i with Pd-1e was completed
in 1 h to afford a 7:93 mixture of 5i and 6i in 71% yield
(entry 9). Iminophosphine 1b was effective also for the
regioselective alkynylstannylation of 4j (entry 10).
Unfortunately, the Pd-1b-catalyzed alkynylstannyla-
tion of an aliphatic acetylene, such as 1-hexyne, did not
give any products even under drastic conditions (90 °C,
26 h). Addition of tributyl(1-hexyn-1-yl)tin (2b) to alkyne
4a , 4e, or 4i in the presence of the optimized catalyst
also proceeded with regioselectivity higher than that of
Pd-1a (entries 11-13).
Ca ta lytic Cycle. The observation of the similar
ligand effect in the alkynylstannylation of alkynes 4a -g
should imply that the reaction proceeds through a
similar catalytic cycle. A plausible catalytic cycle is
depicted in Scheme 6. Oxidative addition of an alkyn-
ylstannane to a Pd(0) complex gives Pd(II) complex 3,
where the alkynyl group is located cis to the imino
moiety as we reported before.11 Dissociation of the imino
group from palladium makes a vacant coordination site
for an alkyne, and the ligand dissociation would take
place prior to insertion of the alkyne.20 Successive
insertion of an alkyne to the C-Pd bond (carbopalla-
dation)21 of 3 followed by reductive elimination is likely
to afford the alkynylstannylation products and regener-
ate the Pd(0) complex. On the basis of the dissociative
a
The reaction was carried out in THF (3 mL) at 50 °C with 2a
(0.34 mmol) and an alkyne (1.0 mmol) in the presence of [PdCl(π-
b
C3H5)]2 (8.2 µmol) and iminophosphine 1 (0.016 mmol). Deter-
mined by 119Sn NMR. c Conversion after 24 h was 13% (entry 3)
d
or 8% (entry 10). Trimethyl(phenylethynyl)tin was used instead
of 2a .
tivity rose to 97:3 with iminophosphine 1c bearing such
a bulky substituent as a t-Bu group on the imino moiety,
although the reaction became slow (entry 3). Pd-1d
gave the alkynylstannylation products with a regio-
selectivity similar to that of Pd-1a , whereas use of 1e
as a ligand retarded the reaction (entries 4 and 5). In
contrast, substituents on phosphorus atom did not
explicitly affect the regioselectivity and the reaction
rate. Thus, a Pd complex coordinated by iminophosphine
1f, where the -PPh2 moiety in 1b is replaced by
-P(o-tolyl)2, gave results similar to 1b (entry 6). The
reaction of trimethyl(phenylethynyl)tin gave the alkyn-
ylstannylation products with almost the same regio-
selectivity as 2a , indicating that the size of the stannyl
group has little influence on the regioselectivity (entry
7). The steric bulk of the imino moiety exerted a similar
influence on the regioselectivity and the reaction rate
in the alkynylstannylation of phenylacetylene (4e). The
acceleration and the high regioselectivity of the reaction
were observed with 1b as a ligand, and Pd-1c complex
gave 5e as the sole product but in only 7% conversion
(entries 8-10). The reaction of ethyl propiolate (4i) with
2a gave 6i predominantly. In this case, Pd-1e complex
was found to exhibit regioselectivity higher than Pd-
1a or Pd-1b complex (entries 11-13).
2. Scop e a n d Lim ita tion s of th e Alk yn ylsta n n yl-
a tion . We next examined the palladium-catalyzed al-
kynylstannylation of various alkynes using the opti-
(20) Dekker, G. P. C. M.; Buijs, A.; Elsevier: C. J .; Vrieze, K.; van
Leeuwen, P. W. N. M.; Smeets, W. J . J .; Spek, A. L.; Wang, Y. F.; Stam,
C. H. Organometallics 1992, 11, 1937-1948.

Alkynylstannylation of Alkynes
Organometallics, Vol. 19, No. 26, 2000 5675
Sch em e 6
Sch em e 8
Sch em e 7
ysis or hydrolysis of 5a afforded alkenyl iodide 11 or
enyne 12, respectively.
Con clu sion
mechanism, the rate acceleration observed with 1b as
a ligand should be reasonable, since such a bulky
substituent as a cyclohexyl group in 1b would facilitate
the dissociation from the palladium center. The dis-
sociation would occur more easily with 1c; excessive
bulkiness of a t-Bu group in 1c should retard the
reaction, inhibiting the coordination of an alkyne.
Compared with an alternative stannylpalladation path-
way, the carbopalladation pathway seems to rationally
explain the results that the regioselectivity and the
reaction rates are definitely affected by the bulkiness
of the imino moiety but to a lesser extent by the size of
the phosphino and stannyl moieties. Predominant pro-
duction of 5 over 6 should be ascribed to the direction
of alkyne coordination leading to the formation of
alkenylpalladium 7, where steric repulsion between R2
and a ligand is disfavored. Accordingly, the increase in
the steric repulsion with bulkier ligands should result
in higher regioselectivities.
Electron-deficient alkynes 4h , 4i, and 4j are likely to
suffer the addition of the alkynyl group in a Michael
fashion, giving 6 predominantly through 8 (Scheme 7).
At present, the reason is not clear why the higher
regioselectivity was observed with 1e than any other
iminophosphine ligand.
Tr an sfor m ation of th e Alkyn ylstan n ylation P r od-
u ct. We confirmed the utility of the alkynylstannylation
products by transformations of 5a to various compounds
(Scheme 8). Cross-coupling22 of 5a with 1-bromo-2-
phenylethyne or 4-nitroiodobenzene gave the corre-
sponding coupled product 9 or 10, respectively.23 Iodol-
We have demonstrated that the alkynylstannylation
of alkynes takes place with palladium-iminophosphine
catalysts to give conjugated (stannyl)enynes in a syn-
selective manner and that the resulting (Z)-alkenyl-
stannanes can be transformed to variously substituted
ethenes. Cyclohexylamine-derived iminophosphine 1b
was found to be a highly active and regioselective ligand
for the palladium-catalyzed alkynylstannylation of vari-
ous alkynes, whereas aniline-derived iminophosphine
1e was suitable for the regioselective alkynylstannyla-
tion of alkyne 4i. The regioselectivities and the reaction
rates depend on the steric bulk of an imino moiety of
iminophosphines, suggesting the insertion of an alkyne
via a dissociative carbopalladation pathway.
Exp er im en ta l Section
Gen er a l Com m en ts. All manipulations of oxygen- and
moisture-sensitive materials were conducted with the standard
Schlenk technique under a purified argon atmosphere (deoxy-
genated by passing through BASF-Catalyst R3-11 column at
80 °C). Nuclear magnetic resonance spectra were taken on a
J EOL EX-270 (1H, 270 MHz; 13C, 67.8 MHz; 31P, 109 MHz;
119Sn, 101 MHz) spectrometer or a Varian Mercury 200 (1H,
200 MHz; 13C, 50 MHz; 31P, 81 MHz) spectrometer with
tetramethylsilane (1H and 13C) as an internal standard or 85%
phosphoric acid (31P) and tetramethyltin (119Sn) as an external
standard. The preparative recycling gel-permeation chroma-
tography (GPC) was performed with J AI LC-908 equipped with
J AIGEL-1H and -2H columns (chloroform as an eluent). High-
resolution mass spectra were obtained with a J EOL J MS-700
spectrometer or a Bruker Bio APEX 70e spectrometer. All
melting points were measured with a Yanagimoto-Seisakusho
micro melting point apparatus and were uncorrected. Unless
otherwise noted, reagents were commercially available and
were used without purification. Tetrahydrofuran (THF) and
1,4-dioxane were distilled from sodium/benzophenone ketyl.
N-[2-(Diphenylphosphino)benzylidene]-2-phenylethylamine
(1a),12 N-[2-(diphenylphosphino)benzylidene]aniline (1e),24 tribu-
tyl(phenylethynyl)tin (2a ),25 tributyl(1-hexyn-1-yl)tin (2b),25
(21) Some reactions may take place through stannylpalladation of
an alkyne. A catalytic cycle of the palladium-catalyzed hydrostannyl-
ation-cyclization of 1,6-diynes is discussed to proceed by similar dual
pathways: Lautens, M.; Smith, N. D.; Ostrovsky, D. J . Org. Chem.
1997, 62, 8970-8971.
(22) Farina, V.; Krishnan, B. J . Am. Chem. Soc. 1991, 113, 9585-
9595.
(23) A [PdCl(π-C3H5)]2-1a complex (5 mol % Pd, Pd:1a ) 1) gave
10 only in 50% yield along with the corresponding (E)-isomer (10%).
For the coupling of organostannanes with aryl halides catalyzed by
Pd-1a , see Shirakawa, E.; Yoshida, H.; Takaya, H. Tetrahedron Lett.
1997, 38, 3759-3762.
(24) Shirakawa, E.; Murota, Y.; Nakao, Y.; Hiyama, T. Synlett 1997,
1143-1144.
(25) Logue, M. W.; Teng, K. J . Org. Chem. 1982, 47, 2549-2553.

5676 Organometallics, Vol. 19, No. 26, 2000
Yoshida et al.
N-propargylacetamide (4c),26 and N-propargylsuccinimide (4d)27
were prepared according to the corresponding literature
procedures.
P r ep a r a tion of Im in op h osp h in es 1b-1d . A mixture of
2-(diphenylphosphino)benzaldehyde15 (0.20 g, 0.69 mmol) and
an amine (0.76 mmol) in toluene (10 mL) was stirred under
reflux. After the time specified below, evaporation of the
solvent followed by GPC gave the corresponding iminophos-
phine.
(3.0 mg, 8.2 µmol), and an alkyne (1.0 mmol) was degassed by
four freeze-thaw cycles. To this solution was added an
organostannane (0.34 mmol), and the mixture was stirred at
the temperature for the given period, both indicated in Tables
1 and 3. Concentration in vacuo followed by GPC purification
gave the corresponding alkynylstannylation product. Yields are
listed in Tables 1 and 3.
Alk yn ylsta n n yla tion of Alk yn es w ith Va r iou s Im in o-
p h osp h in es (Ta ble 2). A THF solution (3 mL) of 1 (0.016
mmol), [PdCl(π-C3H5)]2 (3.0 mg, 8.2 µmol), and an alkyne (1.0
mmol) was degassed by four freeze-thaw cycles. To this
solution was added 2a (0.14 g, 0.34 mmol), and the resulting
mixture was stirred at 50 °C for the time specified in Table 2.
A small part of the reaction mixture was withdrawn, and the
conversion of 2a and the ratio of the alkynylstannylation
products were assayed by 119Sn NMR. The results are sum-
marized in Table 2.
N -[2-(Dip h e n ylp h osp h in o)b e n zylid e n e ]cycloh e xyl-
a m in e (1b). A colorless solid, mp 117-119 °C, 52% yield (3
1
h). H NMR (CDCl3) δ 0.76-1.86 (m, 10 H), 2.86-3.16 (m, 1
H), 6.68-6.92 (m, 1 H), 7.05-7.46 (m, 12 H), 7.85-8.03 (m, 1
H), 8.88 (d, J ) 5.4 Hz, 1 H); 31P{1H} NMR (CDCl3) δ -13.1.
HRMS Calcd for
371.1806.
C
25H26NP: M+, 371.1802. Found: m/z
N -[2-(Dip h e n ylp h osp h in o)b e n zylid e n e ]-t er t -b u t yl-
a m in e (1c). A light yellow solid, mp 114-116 °C, 65% yield
(Z)-4-P h en yl-1-tr ibu tylsta n n yl-1-bu ten -3-yn e (5a ). A
1
1
(13 h). H NMR (CDCl3) δ 1.05 (s, 9 H), 6.72-6.89 (m, 1 H),
brown oil, Rf 0.49 (hexane). H NMR (CDCl3) δ 0.71-1.77 (m,
27 H), 6.69 (s, 2 H), 7.27-7.49 (m, 5 H); 13C NMR (CDCl3) δ
10.2, 13.7, 27.3, 29.2, 89.8, 90.9, 123.5, 126.7, 128.1, 128.3,
131.4, 147.3; 119Sn{1H} NMR (CDCl3) δ -55.5. Anal. Calcd for
7.13-7.53 (m, 12 H), 7.83-8.03 (m, 1 H), 8.77 (d, J ) 5.4 Hz,
1 H); 31P{1H} NMR (CDCl3) δ -11.7. HRMS Calcd for C23H24
-
NP: M+, 345.1645. Found: m/z 345.1649.
N-[2-(Dip h en ylp h osp h in o)ben zylid en e]-2,2-d im eth yl-
p r op yla m in e (1d ). An orange solid, mp 57-62 °C, 59% yield
(3 h). 1H NMR (CDCl3) δ 0.83 (s, 9 H), 3.23 (s, 2 H), 6.75-6.95
(m, 1 H), 7.11-7.72 (m, 12 H), 7.90-8.13 (m, 1 H), 8.82 (d,
J ) 5.0 Hz, 1 H); 31P{1H} NMR (CDCl3) δ -13.3. HRMS Calcd
for C24H26NP: M+, 359.1802. Found: m/z 359.1799.
C
22H34Sn: C, 63.33; H, 8.21. Found: C, 63.53; H, 8.27.
(Z)-2-Meth oxym eth yl-4-p h en yl-1-tr ibu tylsta n n yl-1-bu -
ten -3-yn e (5b). A brown oil, Rf 0.28 (hexane-ethyl acetate )
1
10:1). H NMR (CDCl3) δ 0.73-1.78 (m, 27 H), 3.41 (s, 3 H),
4.07 (d, J ) 1.5 Hz, 2 H), 6.62 (t, J ) 1.5 Hz, 1 H), 7.24-7.53
(m, 5 H); 13C NMR (CDCl3) δ 10.1, 13.7, 27.3, 29.2, 58.0, 89.4,
90.1, 123.3, 128.1, 128.2, 131.5, 136.9, 140.1; 119Sn{1H} NMR
(CDCl3) δ -55.7. Anal. Calcd for C24H38OSn: C, 62.49; H, 8.30.
Found: C, 62.26; H, 8.07.
N-[2-{Bis(o-tolyl)p h osp h in o}ben zylid en e]cycloh exyl-
a m in e (1f). To a solution of 2-(2-bromophenyl)-1,3-dioxolane
(0.34 g, 1.5 mmol) in THF (10 mL) was added dropwise
butyllithium (1.5 M in hexanes, 1.1 mL, 1.6 mmol) at -78 °C.
The reaction mixture was stirred for 1 h at -78 °C. To the
mixture was added dropwise via a cannula a solution of diethyl
chlorophosphonite (0.24 g, 1.5 mmol) in THF (5 mL) at -78
°C. The resulting mixture was allowed to warm slowly to room
temperature and stirred for 7 h. A solution of 2-methylphen-
yllithium (3.0 mmol) in THF (10 mL), prepared from 2-bro-
motoluene (0.51 g, 3.0 mmol) and butyllithium (1.5 M in
hexanes, 2.2 mL, 3.3 mmol) in a similar manner as above, was
added dropwise to the mixture via a cannula at -78 °C. The
mixture was allowed to warm slowly to room temperature over
16 h before dilution with ethyl acetate (60 mL). The organic
(Z)-1-Meth oxym eth yl-4-p h en yl-1-tr ibu tylsta n n yl-1-bu -
ten -3-yn e (6b). A brown oil, Rf 0.39 (hexane-ethyl acetate )
1
10:1). H NMR (CDCl3) δ 0.75-1.77 (m, 27 H), 3.33 (s, 3 H),
4.11 (d, J ) 1.6 Hz, 2 H), 6.51 (t, J ) 1.6 Hz, 1 H), 7.20-7.51
(m, 5 H); 13C NMR (CDCl3) δ 10.2, 13.7, 27.4, 29.2, 57.9, 79.1,
89.8, 119.56, 119.62, 128.0, 128.3, 131.3, 159.9; 119Sn{1H} NMR
(CDCl3) δ -48.9. Anal. Calcd for C24H38OSn: C, 62.49; H, 8.30.
Found as a mixture of 5b and 6b: C, 62.79; H, 8.15.
(Z)-2-Aceta m id om eth yl-4-p h en yl-1-tr ibu tylsta n n yl-1-
bu ten -3-yn e (5c). A brown oil, Rf 0.33 (hexane-ethyl acetate
1
) 1:1). H NMR (CDCl3) δ 0.72-1.70 (m, 27 H), 2.03 (s, 3 H),
4.00-4.10 (m, 2 H), 5.92 (br s, 1 H), 6.46 (s, 1 H), 7.22-7.46
(m, 5 H); 13C NMR (CDCl3) δ 10.1, 13.7, 23.4, 27.3, 29.2, 47.3,
89.9, 90.0, 123.0, 128.4, 131.5, 136.4, 140.0, 169.8; 119Sn{1H}
NMR (CDCl3) δ -56.1. Anal. Calcd for C25H39NOSn: C, 61.49;
H, 8.05. Found as a mixture of 5c and 6c: C, 61.62; H, 7.99.
(Z)-1-Aceta m id om eth yl-4-p h en yl-1-tr ibu tylsta n n yl-1-
bu ten -3-yn e (6c). A brown oil, Rf 0.35 (hexane-ethyl acetate
layer was separated, washed with
a saturated NaHCO3
aqueous solution, and dried over anhydrous magnesium
sulfate. Evaporation of the solvent gave a crude product, which
was then treated with p-toluenesulfonic acid monohydrate
(0.022 g, 0.12 mmol) in acetone at reflux temperature for 8 h
with stirring. Evaporation of the solvent followed by silica gel
column chromatography with 20% ethyl acetate in hexane as
an eluent gave 2-[bis(o-tolyl)phosphino]benzaldehyde [0.23 g,
47% yield based on 2-(2-bromophenyl)-1,3-dioxolane] as a
yellow solid, mp 106-112 °C. 1H NMR (CDCl3) δ 2.42 (s, 6 H),
6.58-7.64 (m, 11 H), 7.89-8.10 (m, 1 H), 10.60 (d, J ) 6.2 Hz,
1 H); 31P{1H} NMR (CDCl3) δ -28.8. HRMS (ESI) Calcd for
1
) 1:1). H NMR (CDCl3) δ 0.69-1.71 (m, 27 H), 2.00 (s, 3 H),
3.97-4.20 (m, 2 H), 5.42 (br s, 1 H), 6.42 (s, 1 H), 7.23-7.45
(m, 5 H); 13C NMR (CDCl3) δ 10.1, 13.7, 23.3, 27.4, 29.2, 47.7,
89.5, 90.5, 120.2, 123.4, 128.1, 128.3, 131.3, 158.4, 169.4; 119Sn-
{1H} NMR (CDCl3) δ -46.0. Anal. Calcd for C25H39NOSn: C,
61.49; H, 8.05. Found as a mixture of 5c and 6c: C, 61.62; H,
7.99.
C
21H19OPNa: M+ + Na, 341.1066. Found: m/z 341.1066.
A mixture of 2-[bis(o-tolyl)phosphino]benzaldehyde (0.080
(Z)-2-Su ccin im id om eth yl-4-p h en yl-1-tr ibu tylsta n n yl-
1-bu ten -3-yn e (5d ). A brown oil, Rf 0.47 (hexane-ethyl
g, 0.25 mmol) and cyclohexylamine (0.027 g, 0.28 mmol) in
toluene (5 mL) was stirred at reflux temperature for 2.5 h.
Concentration in vacuo followed by GPC gave 1f (0.080 g, 79%
yield) as a colorless solid, mp 119-121 °C. 1H NMR (CDCl3) δ
0.80-2.07 (m, 10 H), 2.39 (s, 6 H), 2.87-3.24 (m, 1 H), 6.54-
7.53 (m, 11 H), 7.86-8.25 (m, 1 H), 8.92 (d, J ) 5.5 Hz, 1 H);
31P{1H} NMR (CDCl3) δ -29.9. HRMS Calcd for C27H30NP:
M+, 399.2114. Found: m/z 399.2115.
1
acetate ) 1:1). H NMR (CDCl3) δ 0.72-1.67 (m, 27 H), 2.75
(s, 4 H), 4.35 (d, J ) 1.3 Hz, 2 H), 6.46 (t, J ) 1.3 Hz, 1 H),
7.20-7.45 (m, 5 H); 13C NMR (CDCl3) δ 10.2, 13.7, 27.3, 28.2,
29.1, 45.9, 89.3, 89.8, 122.9, 128.4, 131.4, 133.1, 141.5, 176.5;
119Sn{1H} NMR (CDCl3) δ -54.7. Anal. Calcd for C27H39NO2-
Sn: C, 61.38; H, 7.44. Found: C, 61.26; H, 7.55.
(Z)-1-Su ccin im id om eth yl-4-p h en yl-1-tr ibu tylsta n n yl-
1-bu ten -3-yn e (6d ). A brown oil, Rf 0.49 (hexane-ethyl
Alk yn ylsta n n yla tion of Alk yn es: A Gen er a l P r oce-
d u r e. A solution (3 mL) of 1 (0.016 mmol), [PdCl(π-C3H5)]2
1
acetate ) 1:1). H NMR (CDCl3) δ 0.75-1.70 (m, 27 H), 2.77
(s, 4 H), 4.32 (d, J ) 2.0 Hz, 2 H), 6.12 (t, J ) 2.0 Hz, 1 H),
7.16-7.45 (m, 5 H); 13C NMR (CDCl3) δ 10.2, 13.6, 27.3, 28.2,
29.0, 45.3, 89.2, 90.8, 118.9, 123.4, 128.1, 128.3, 131.2, 154.5,
(26) Armin, D. M.; J oern, S. T.; Raphael, K.; Frank, G.; Torsten,
M.; Tim, B. Synthesis 1991, 547-560.
(27) Paul, M.; Hassan, I. Tetrahedron: Asymmetry 1998, 9, 4419-
4428.
176.5; 119Sn{1H} NMR (CDCl3) δ -43.5. Anal. Calcd for C27H39
-

Alkynylstannylation of Alkynes
Organometallics, Vol. 19, No. 26, 2000 5677
NO2Sn: C, 61.38; H, 7.44. Found as a mixture of 5d and 6d :
C, 61.54; H, 7.41.
(Z)-6-P h en yl-3-tr ibu tylstan n yl-3-h exen -5-yn e-2-on e (6j).
A brown oil, Rf 0.37 (hexane-ethyl acetate ) 10:1). H NMR
1
(CDCl3) δ 0.74-1.70 (m, 27 H), 2.50 (s, 3 H), 7.30-7.54 (m, 6
H); 13C NMR (CDCl3) δ 11.4, 13.7, 25.9, 27.3, 29.1, 88.6, 99.4,
122.6, 128.5, 129.0, 131.3, 131.6, 161.8, 204.1; 119Sn{1H} NMR
(CDCl3) δ -39.5. Anal. Calcd for C24H36OSn: C, 62.77; H, 7.90.
Found: C, 62.90; H, 8.09.
(Z)-1-Tr ibu tylsta n n yl-1-octen -3-yn e (5k ). A brown oil, Rf
0.68 (hexane). 1H NMR (CDCl3) δ 0.77-1.70 (m, 34 H), 2.31
(t, J ) 6.3 Hz, 2 H), 6.44 (s, 2 H); 13C NMR (CDCl3) δ 10.0,
13.6, 13.7, 19.2, 22.1, 27.3, 29.2, 30.8, 82.0, 91.0, 127.2, 144.3;
119Sn{1H} NMR (CDCl3) δ -57.0. Anal. Calcd for C20H38Sn:
C, 60.47; H, 9.64. Found: C, 60.21; H, 9.44.
(Z)-2,4-Dip h en yl-1-tr ibu tylsta n n yl-1-bu ten -3-yn e (5e).
A brown oil, Rf 0.39 (hexane). 1H NMR (CDCl3) δ 0.70-1.91
(m, 27 H), 6.95-7.88 (m, 11 H); 13C NMR (CDCl3) δ 10.2, 13.7,
27.4, 29.2, 89.9, 91.1, 123.4, 125.9, 127.8, 128.2, 128.3, 131.5,
138.9, 139.4, 140.9; 119Sn{1H} NMR (CDCl3) δ -54.3. Anal.
Calcd for C28H38Sn: C, 68.17; H, 7.76. Found: C, 68.35; H,
7.63.
(Z)-1,4-Dip h en yl-1-tr ibu tylsta n n yl-1-bu ten -3-yn e (6e).
A brown oil, Rf 0.39 (hexane). 1H NMR (CDCl3) δ 0.62-1.76
(m, 27 H), 6.50 (s, 1 H), 7.02-7.78 (m, 10 H); 13C NMR (CDCl3)
δ 11.1, 13.6, 27.3, 29.1, 90.6, 91.3, 121.4, 123.6, 126.4, 126.5,
128.1, 128.2, 128.3, 131.3, 146.2, 163.0; 119Sn{1H} NMR
(CDCl3) δ -43.0. Anal. Calcd for C28H38Sn: C, 68.17; H, 7.76.
Found as a mixture of 5e and 6e: C, 68.16; H, 7.88.
(Z)-2-(4-Met h ylp h en yl)-4-p h en yl-1-t r ib u t ylst a n n yl-1-
bu ten -3-yn e (5f). A brown oil, Rf 0.39 (hexane). 1H NMR
(CDCl3) δ 0.77-1.84 (m, 27 H), 2.36 (s, 3 H), 7.06-7.74 (m, 10
H); 13C NMR (CDCl3) δ 10.2, 13.7, 21.1, 27.4, 29.2, 89.7, 91.2,
123.5, 125.8, 128.2, 128.3, 128.9, 131.5, 136.8, 137.7, 138.8,
(Z)-2-P h en yl-1-t r ib u t ylst a n n yl-1-oct en -3-yn e (5l). A
1
brown oil, Rf 0.45 (hexane). H NMR (CDCl3) δ 0.76-1.85 (m,
34 H), 2.42 (t, J ) 7.0 Hz, 2 H), 6.93 (s, 1 H), 7.20-7.83 (m, 5
H); 13C NMR (CDCl3) δ 10.1, 13.6, 13.7, 19.3, 22.2, 27.4, 29.2,
30.8, 82.1, 91.1, 125.9, 127.6, 128.1, 138.2, 139.3, 139,9; 119Sn-
{1H} NMR (CDCl3) δ -55.3. Anal. Calcd for C26H42Sn: C,
65.98; H, 8.94. Found: C, 66.19; H, 9.02.
(Z)-1-P h en yl-1-t r ib u t ylst a n n yl-1-oct en -3-yn e (6l). A
139.6; 119Sn{1H} NMR (CDCl3) δ -54.5. Anal. Calcd for C29H40
Sn: C, 68.66; H, 7.95. Found: C, 68.57; H, 7.86.
-
1
brown oil, Rf 0.37 (hexane). H NMR (CDCl3) δ 0.63-1.79 (m,
34 H), 2.34 (td, J ) 7.0 and 2.2 Hz, 2 H), 6.25 (t, J ) 2.2 Hz,
1 H), 6.92-7.39 (m, 5 H); 13C NMR (CDCl3) δ 10.9, 13.6, 13.7,
19.5, 22.1, 27.3, 29.1, 30.8, 81.5, 92.6, 122.0, 126.1, 126.4, 127.2,
128.1, 129.5; 119Sn{1H} NMR (CDCl3) δ -45.0. Anal. Calcd for
(Z)-1-(4-Met h ylp h en yl)-4-p h en yl-1-t r ib u t ylst a n n yl-1-
bu ten -3-yn e (6f). A brown oil, Rf 0.31 (hexane). 1H NMR
(CDCl3) δ 0.71-1.90 (m, 27 H), 2.35 (s, 3 H), 6.49 (s, 1 H),
6.97-7.58 (m, 9 H); 13C NMR (CDCl3) δ 11.1, 13.7, 21.1, 27.3,
29.1, 90.8, 91.2, 120.8, 123.7, 126.3, 128.0, 128.3, 128.9, 131.3,
136.2, 143.2, 162.7; 119Sn{1H} NMR (CDCl3) δ -43.7. Anal.
Calcd for C29H40Sn: C, 68.66; H, 7.95. Found as a mixture of
5f and 6f: C, 68.50; H, 7.96.
(E )-2-E t h oxy-4-p h e n yl-1-t r ib u t ylst a n n yl-1-b u t e n -3-
yn e (5g). A brown oil, Rf 0.65 (hexane-ethyl acetate ) 10:1).
1H NMR (CDCl3) δ 0.68-1.73 (m, 30 H), 4.04 (q, J ) 7.1 Hz,
2 H), 5.52 (s, 1 H), 7.17-7.56 (m, 5 H); 13C NMR (CDCl3) δ
10.3, 13.7, 15.2, 27.3, 29.2, 83.6, 89.7, 113.8, 122.6, 128.2, 128.3,
128.5, 131.6, 147.1; 119Sn{1H} NMR (CDCl3) δ -51.1. Anal.
Calcd for C24H38OSn: C, 62.49; H, 8.30. Found: C, 62.46; H,
8.40.
Eth yl (Z)-3-Meth yl-5-ph en yl-2-tr ibu tylstan n yl-2-pen ten -
4-yn oa te (6h ). A brown oil, Rf 0.45 (hexane-ethyl acetate )
9:1). 1H NMR (CDCl3) δ 0.74-1.67 (m, 30 H), 2.14 (s, 3 H),
4.21 (q, J ) 7.1 Hz, 2 H), 7.19-7.52 (m, 5 H); 13C NMR (CDCl3)
δ 11.1, 13.6, 14.4, 22.7, 27.2, 28.9, 60.3, 91.1, 92.3, 122.9, 128.4,
128.5, 131.5, 134.8, 145.0, 171.9; 119Sn{1H} NMR (CDCl3) δ
-36.0. Anal. Calcd for C26H40O2Sn: C, 62.04; H, 8.01. Found:
C, 62.33; H, 8.25.
Eth yl (E)-2-P h en yleth yn yl-3-tr ibu tylsta n n yl-2-p r op en -
oa te (5i). A brown oil, Rf 0.31 (hexane-ethyl acetate ) 10:1).
1H NMR (CDCl3) δ 0.62-1.78 (m, 30 H), 4.28 (q, J ) 7.1 Hz,
2 H), 7.25-7.54 (m, 5 H), 8.04 (s, 1 H); 13C NMR (CDCl3) δ
10.2, 13.6, 14.2, 27.3, 29.1, 61.6, 87.9, 90.9, 123.1, 128.3, 128.4,
131.4, 131.6, 159.2, 163.5; 119Sn{1H} NMR (CDCl3) δ -52.0.
Anal. Calcd for C25H38O2Sn: C, 61.37; H, 7.83. Found as a
mixture of 5i and 6i: C, 61.64; H, 7.58.
C
26H42Sn: C, 65.98; H, 8.94. Found as a mixture of 5l and 6l:
C, 66.15; H, 9.12.
Eth yl (E)-2-(1-Hexyn -1-yl)-3-tr ibu tylsta n n yl-2-p r op en -
oa te (5m ). A brown oil, Rf 0.55 (hexane-ethyl acetate ) 10:
1). 1H NMR (CDCl3) δ 0.75-1.77 (m, 37 H), 2.38 (t, J ) 7.0
Hz, 2 H), 4.23 (q, J ) 7.1 Hz, 2 H), 7.82 (s, 1 H); 13C NMR
(CDCl3) δ 10.0, 13.6, 13.7, 14.2, 19.3, 22.1, 27.3, 29.1, 30.6,
61.4, 79.1, 92.3, 131.6, 156.5, 163.9; 119Sn{1H} NMR (CDCl3)
δ -53.2. Anal. Calcd for C23H42O2Sn: C, 58.87; H, 9.02. Found
as a mixture of 5m and 6m : C, 58.91; H, 9.14.
Eth yl (Z)-2-Tr ibu tylsta n n yl-2-n on en -4-yn oa te (6m ). A
brown oil, Rf 0.59 (hexane-ethyl acetate ) 10:1). 1H NMR
(CDCl3) δ 0.72-1.65 (m, 37 H), 2.31 (td, J ) 7.0 and 2.4 Hz, 2
H), 4.10 (q, J ) 7.1 Hz, 2 H), 7.18 (t, J ) 2.4 Hz, 1 H); 13C
NMR (CDCl3) δ 11.2, 13.6, 13.7, 14.3, 19.6, 22.1, 27.3, 29.0,
30.4, 60.7, 80.4, 100.1, 134.5, 147.7, 171.1; 119Sn{1H} NMR
(CDCl3) δ -40.2. Anal. Calcd for C23H42O2Sn: C, 58.87; H, 9.02.
Found: C, 58.93; H, 9.10.
Cou p lin g of 5a w ith 1-Br om o-2-p h en yleth yn e. A solu-
tion of tri(2-furyl)phosphine (0.010 g, 0.044 mmol) and Pd2-
(dba)3 (5.0 mg, 5.5 µmol) in 1-methyl-2-pyrrolidinone (NMP,
2.5 mL) was degassed by three freeze-thaw cycles. To this
solution was added 1-bromo-2-phenylethyne (0.040 g, 0.22
mmol) and 5a (0.10 g, 0.24 mmol), and the resulting mixture
was stirred at 50 °C for 18 h before a 1 M KF aqueous solution
(2 mL) was added. The mixture was stirred at room temper-
ature for 30 min, filtered through a Celite plug, and extracted
with ethyl acetate (50 mL). The organic layer was separated,
washed successively with water and brine, and dried over
anhydrous magnesium sulfate. Evaporation of the solvent
followed by GPC gave (Z)-1,6-diphenyl-3-hexen-1,5-diyne (9)28
(0.029 g, 58%) as a colorless oil: 1H NMR (CDCl3) δ 6.10 (s, 2
H), 7.23-7.63 (m, 10 H).
Cou p lin g of 5a w ith 4-Nitr oiod oben zen e: A. With P d 2-
(d ba )3-Tr i(2-fu r yl)p h osp h in e. A solution of tri(2-furyl)-
phosphine (0.020 g, 0.088 mmol) and Pd2(dba)3 (0.010 g, 0.011
mmol) in toluene (5 mL) was degassed by three freeze-thaw
cycles. To this solution was added 4-nitroiodobenzene (0.11 g,
0.44 mmol) and 5a (0.20 g, 0.48 mmol), and the mixture was
stirred at 90 °C for 13 h before the addition of a 1 M KF
aqueous solution (2 mL). The mixture was stirred at room
temperature for 30 min, filtered through a Celite plug, and
Eth yl (Z)-5-P h en yl-2-tr ibu tylstan n yl-2-pen ten -4-yn oate
(6i). A brown oil, Rf 0.41 (hexane-ethyl acetate ) 10:1). 1H
NMR (CDCl3) δ 0.86 (t, J ) 7.1 Hz, 9 H), 0.96-1.76 (m, 21 H),
4.21 (q, J ) 7.1 Hz, 2 H), 7.27-7.54 (m, 6 H); 13C NMR (CDCl3)
δ 11.4, 13.7, 14.3, 27.3, 29.0, 60.9, 89.0, 97.7, 122.7, 128.4,
128.9, 131.6, 133.4, 150.0, 170.9; 119Sn{1H} NMR (CDCl3) δ
-38.3. Anal. Calcd for C25H38O2Sn: C, 61.37; H, 7.83. Found:
C, 61.53; H, 7.65.
(E)-3-P h en ylet h yn yl-4-t r ib u t ylst a n n yl-3-b u t en -2-on e
(5j). A brown oil, Rf 0.44 (hexane-ethyl acetate ) 10:1). 1H
NMR (CDCl3) δ 0.73-1.68 (m, 27 H), 2.33 (s, 3 H), 7.16-7.58
(m, 5 H), 7.91 (s, 1 H); 13C NMR (CDCl3) δ 10.2, 13.6, 27.3,
27.5, 29.1, 88.9, 92.1, 122.8, 128.4, 128.6, 131.4, 139.0, 156.7,
194.2; 119Sn{1H} NMR (CDCl3) δ -50.7. Anal. Calcd for C24H36
-
OSn: C, 62.77; H, 7.90. Found as a mixture of 5j and 6j: C,
(28) Vollhardt, K. P. C.; Winn, L. S. Tetrahedron Lett. 1985, 26, 709-
712.
63.03; H, 7.82.

5678 Organometallics, Vol. 19, No. 26, 2000
Yoshida et al.
extracted with ethyl acetate (50 mL). The organic layer was
separated, washed successively with water and brine, and
dried over anhydrous magnesium sulfate. Evaporation of the
solvent followed by GPC gave (Z)-1-(4-nitrophenyl)-4-phenyl-
1-buten-3-yne (10)29 (0.093 g, 85%) as a yellow solid: 1H NMR
(CDCl3) δ 6.16 (d, J ) 11.9 Hz, 1 H), 6.77 (d, J ) 11.9 Hz, 1
H), 7.29-7.59 (m, 5 H), 7.96-8.14 (m, 2 H), 8.17-8.33 (m, 2
H).
B. With [P d Cl(π-C3H5)]2-1a . A solution of 1a (8.6 mg,
0.022 mmol), 4-nitroiodobenzene (0.11 g, 0.44 mmol), and
[PdCl(π-C3H5)]2 (4.0 mg, 0.011 mmol) in toluene (5 mL) was
degassed by three freeze-thaw cycles. To this solution was
added 5a (0.20 g, 0.48 mmol) and the mixture was stirred at
90 °C for 13 h. After a 1 M KF aqueous solution (2 mL) was
added, the reaction mixture was stirred at room temperature
for 30 min. Filtration through a Celite plug was followed by
extraction with ethyl acetate (50 mL). The organic layer was
washed successively with water and brine and dried over
anhydrous magnesium sulfate. Evaporation of the solvent
followed by GPC gave a mixture of (Z)-1-(4-nitrophenyl)-4-
phenyl-1-buten-3-yne (10) and (E)-1-(4-nitrophenyl)-4-phenyl-
1-buten-3-yne (0.066 g, 83:17 ratio, 60%) as a yellow solid.
Iod od esta n n yla tion of 5a . To a solution of 5a (0.10 g, 0.24
mmol) in THF (4 mL) was added iodine (0.087 g, 0.34 mmol)
at 0 °C, and the resulting reaction mixture was stirred for 40
min before ethyl acetate (10 mL) and a saturated Na2S2O3
aqueous solution (5 mL) were added. After the organic layer
was treated with a 1 M KF aqueous solution (2 mL) at room
temperature for 30 min, insoluble materials were filtered
through a Celite pad, and the organic layer was dried over
magnesium sulfate. Evaporation of the solvent followed by
GPC gave (Z)-1-iodo-4-phenyl-1-buten-3-yne (11) (0.056 g, 92%)
as a colorless oil: 1H NMR (CDCl3) δ 6.82 (d, J ) 8.3 Hz, 1
H), 6.86 (d, J ) 8.3 Hz, 1 H), 7.30-7.39 (m, 3 H), 7.49-7.58
(m, 2 H). Anal. Calcd for C10H7I: C, 42.27; H, 2.78. Found: C,
42.27; H, 2.89.
Hyd r olysis of 5a . A mixture of 5a (0.058 g, 0.14 mmol)
and concentrated hydrochloric acid (12 M, 80 µL, 0.96 mmol)
in THF (8 mL) was stirred at room temperature for 1 h. After
the addition of ethyl acetate (20 mL) to the reaction mixture,
the organic layer was washed with saturated NaHCO3 aqueous
solution (5 mL) and dried over anhydrous magnesium sulfate.
Evaporation of the solvent followed by GPC gave 4-phenyl-1-
buten-3-yne (12)30 (0.015 g, 81%) as a colorless oil: 1H NMR
(CDCl3) δ 5.55 (dd, J ) 11.0 and 2.4 Hz, 1 H), 5.73 (dd, J )
17.6 and 2.4 Hz, 1 H), 6.03 (dd, J ) 17.6 and 11.0 Hz, 1 H),
7.01-7.60 (m, 5 H).
OM000828U
(29) Saikachi, H.; Shimojyo, N.; Ogawa, H. Yakugaku Zasshi 1970,
90, 581-587.
(30) Padwa, A.; Caruso, T.; Nahm, S.; Rodriguez, A. J . Am. Chem.
Soc. 1982, 104, 2865-2871.