Insertion of alkynes into an ArS-Pt bond: Regio- and stereoselective thermal reactions, facilitation by "o-halogen effect" and photoirradiation, different alkyne preferences depending on the ancillary ligand, and application to a catalytic reaction

Article abstract of DOI:10.1021/om800464y

The insertion of alkyne 2 into the S-Pt bond(s) of Pt(SAr)(Cl)(PPh ₃)₂ (7), Pt(SAr)₂(PPh₃)₂ (8), and Pt(SAr)(Ar′)(dppe) (9) has been investigated. Regioselective c/s-insertion into the S-Pt bond of trans-7 took place with terminal and internal alkynes (RC≡CR′; R′ = H, C(O)OEt, and CH ₂OMe) at 70-110 °C to give Pt[(Z)-C(R′)=C(SAr)R](Cl) (PPh₃)₂ (Z-10) as stable compounds. The introduction of an electron-donating group in Ar of ArC≡CH and in ArS of 7 slightly facilitated the reactions. It was found that a halogen atom at the ortho position in ArS of 7 dramatically promoted the insertion ("o-halogen effect"). The insertion of a terminal alkyne (2, RC≡CH) into the S-Pt bond of trans-Pt(SAr)₂(PPh₃)₂ (8) also occurred to afford Pt[(Z)-C(H)=C(SAr)R](SAr)(PPh₃)₂ (Z-16), which was further converted into Pt(PPh₃) ₂(RC≡CH) (18) and (Z,Z)-(ArS)(R)C=C(H)-C(H)=C(SAr)(R) (19) by C-C bond-forming reductive elimination after the insertion of another 2 into the remaining S-Pt bond of 16. The "o-halogen effect" was also observed for the insertion of 2 into the S-Pt bond of trans-8 to furnish the corresponding cis-Z-16 as a kinetic product; the trans-isomer of 8 exhibited a higher reactivity than the cis-isomer. It was also revealed that photoirradiation (visible light) dramatically promoted the insertion of 2 into the S-Pt bond of trans-8. Photoinduced insertion was facilitated by introducing an electron-donating group into Ar of ArC≡CH. Contrary to the cases of PPh₃-ligated platinum complexes, the insertion into the S-Pt bond of Pt(SAr)(Ar′)(dppe) (9) was realized when the electron-deficient alkyne DMAD (2t) was employed as a substrate. Also presented is the insertion of two alkynes into each S-Pt bond of 8 in the Pt-catalyzed stereo- and regioselective dimerization-bisthiolation of alkyne (2) by diaryl disulfide ((ArS)₂, 30) to yield functionalized symmetrical 1,3-dienes.

Full text of DOI:10.1021/om800464y

4788
Organometallics 2008, 27, 4788–4802
Insertion of Alkynes into an ArS-Pt Bond: Regio- and
Stereoselective Thermal Reactions, Facilitation by “o-Halogen
Effect” and Photoirradiation, Different Alkyne Preferences
Depending on the Ancillary Ligand, and Application to a Catalytic
Reaction
Hitoshi Kuniyasu,* Kazunobu Takekawa, Fumikazu Yamashita, Kiyoshi Miyafuji,
Shigehito Asano, Yasutomo Takai, Atsushi Ohtaka, Aoi Tanaka, Kunihiko Sugoh,
Hideo Kurosawa, and Nobuaki Kambe*
Department of Applied Chemistry, Graduate School of Engineering, Osaka UniVersity,
Suita, Osaka 565-0871, Japan
ReceiVed May 21, 2008
The insertion of alkyne 2 into the S-Pt bond(s) of Pt(SAr)(Cl)(PPh3)2 (7), Pt(SAr)2(PPh3)2 (8), and
Pt(SAr)(Ar′)(dppe) (9) has been investigated. Regioselective cis-insertion into the S-Pt bond of trans-7
took place with terminal and internal alkynes (RCt CR′; R′ ) H, C(O)OEt, and CH2OMe) at 70-110
°C to give Pt[(Z)-C(R′)dC(SAr)R](Cl)(PPh3)2 (Z-10) as stable compounds. The introduction of an electron-
donating group in Ar of ArCt CH and in ArS of 7 slightly facilitated the reactions. It was found that a
halogen atom at the ortho position in ArS of 7 dramatically promoted the insertion (“o-halogen effect”).
The insertion of a terminal alkyne (2, RCt CH) into the S-Pt bond of trans-Pt(SAr)2(PPh3)2 (8) also
occurred to afford Pt[(Z)-C(H)dC(SAr)R](SAr)(PPh3)2 (Z-16), which was further converted into
Pt(PPh3)2(RCt CH) (18) and (Z,Z)-(ArS)(R)CdC(H)-C(H)dC(SAr)(R) (19) by C-C bond-forming
reductive elimination after the insertion of another 2 into the remaining S-Pt bond of 16. The “o-halogen
effect” was also observed for the insertion of 2 into the S-Pt bond of trans-8 to furnish the corresponding
cis-Z-16 as a kinetic product; the trans-isomer of 8 exhibited a higher reactivity than the cis-isomer. It
was also revealed that photoirradiation (visible light) dramatically promoted the insertion of 2 into the
S-Pt bond of trans-8. Photoinduced insertion was facilitated by introducing an electron-donating group
into Ar of ArCt CH. Contrary to the cases of PPh3-ligated platinum complexes, the insertion into the
S-Pt bond of Pt(SAr)(Ar′)(dppe) (9) was realized when the electron-deficient alkyne DMAD (2t) was
employed as a substrate. Also presented is the insertion of two alkynes into each S-Pt bond of 8 in the
Pt-catalyzed stereo- and regioselective dimerization-bisthiolation of alkyne (2) by diaryl disulfide ((ArS)2,
30) to yield functionalized symmetrical 1,3-dienes.
moieties.1 In contrast, the utility of transition metal-catalyzed
addition reactions with organic sulfur compounds, which have
Introduction
Transition metal-catalyzed addition reactions of heteroatom-
containing σ-bonds to unsaturated compounds, represented by
hydrosilylation of alkenes and alkynes, have been extensively
explored for more than three decades and serve as a straight-
forward strategy to introduce functional groups into unsaturated
been known to act as a “catalyst poison”,2 has not been well-
studied until recently, although Reppe’s early study had sug-
gested that reactions with such a combination of catalysts and
reagents could be very rewarding.3 After some scattered works
were published during the 1960s and 1980s,4 a variety of regio-
and stereoselective metal-catalyzed addition reactions of the
compounds RS-G (G ) H,5 9-BBN,6 CO2Me,7 SiCl3,8
C(O)NR2,9 Ar′ (from ArSC(O)Ar′),10 CH2CHdCH2,11 P(O)-
(OPh)2,12 and SAr13) to terminal alkynes (2, RCt CH) have been
conducted since the early 1990s (Scheme 1).14 These examples
clearly demonstrate that the concept of “catalytic poison” does
* Corresponding authors. E-mail: kuni@chem.eng.osaka-u.ac.jp.
(1) (a) For reviews, see: Ojima, I. In The Chemistry of Organic Silicon
Compounds; Patai, S., Rapport, Z., Eds.; Wiley-Interscience: Chichester,
1989; Chapter 25. (b) Tsuji, J. Palladium Reagents and Catalysts:
InnoVations in Organic Synthesis; Wiley: Chichester, 1995; pp 488-497.
(c) Hiyama, T.; Kusumoto, T. In ComprehensiVe Organic Synthesis; Trost,
B. M., Ed.; Pargamon: Oxford, 1991; Vol. 8, p 763. (d) Ojima, I. In The
Chemistry of Organic Silicon Compounds; Rappoport, Z., Apeloig, Y., Eds.;
Wiley: Chichester, 1998; Vol. 2, Part 2, p 1687. (e) Hiyama, T.; Shirakawa,
E. Top. Curr. Chem. 2002, 219, 60. (f) Recatto, C. A. Aldrichim. Acta 1995,
28, 85. (g) Horn, K. A. Chem. ReV. 1995, 95, 1317. (h) Murai, S.; Chatani,
N. J. Synth. Org. Chem. Jpn. 1993, 51, 421. (i) Okinoshima, H.; Yamamoto,
K.; Kumada, M. J. Am. Chem. Soc. 1972, 94, 9263. (j) Togni, A.,
Grutzmacher, H., Eds. Catalytic Heterofunctionalization; Wiley-VCH:
Weinheim, 2001. (k) Miyaura, N. Top. Curr. Chem. 2002, 219, 11. (l)
Beletskaya, I.; Pelter, A. Tetrahedron 1997, 53, 4957. (m) Miyaura, N.;
Suzuki, A. Chem. ReV. 1995, 95, 2457. (n) Suzuki, A.; Miyaura, N. J. Synth.
Org. Chem. Jpn. 1993, 51, 1043. (o) Burgess, K.; Ohlmeyer, M. J. Chem.
ReV. 1991, 91, 1179.
(2) (a) Hegedus, L. L.; McCabe, R. W. Catalyst Poisoning; Marcel
Dekker: New York, 1984. (b) Hutton, A. T. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McClverty, J. A., Eds.; Pergamon
Press: Oxford, U.K., 1984; Vol. 5, p 1151.
(3) (a) Reppe, V. W. Liebigs Ann. 1953, 582, 1. (b) Reppe, V. W.;
Kro¨per, H. Liebigs Ann. 1953, 582, 38.
(4) (a) Holmquist, H. E.; Carnahan, J. E. J. Org. Chem. 1960, 25, 2240.
(b) Knifton, J. F. U.S. Patent 3,933,884, 1976. (c) Foley, P. U.S. Patent
4,422,977, 1983. (d) Antebi, S.; Alper, H. Organometallics 1986, 5, 596.
(e) Dzhemilev, U. M.; Kunakova, R. V.; Gaisin, R. L. IzV. Akad. Nauk
SSSR, Ser. Khim. 1981, 11, 2655. (f) Antebi, S.; Alper, H. Tetrahedron
Lett. 1985, 26, 2609.
10.1021/om800464y CCC: $40.75
2008 American Chemical Society
Publication on Web 08/23/2008

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4789
Scheme 1. M-Catalyzed Addition of ArS-G (1) to Alkynes
(2)
not connote a lack of promise for the transition metal-catalyzed
reactions using organic sulfur compounds as reaction substrates.
Furthermore, a DFT study indicates that S-M bonds can exhibit
moderate reactivity in catalytic transformation (bond energy of
CH3S-Pd is 48.4 kcal/mol).15 Most reactions shown in Scheme
1 have been conducted using PR3-ligated Ni triad catalysts to
afford vinyl sulfides (3) with an ArS group at the internal carbon
and G at the terminal carbon in a cis fashion with one another.
(5) (a) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Kambe, N.; Sonoda,
N. J. Am. Chem. Soc. 1992, 114, 5902. (b) Ba¨ckvall, J. E.; Ericsson, A. J.
Org. Chem. 1994, 59, 5850. (c) Ogawa, A.; Ikeda, T.; Kimura, K.; Hirao,
T. J. Am. Chem. Soc. 1999, 121, 5108. (d) Ogawa, A. J. Organomet. Chem.
2000, 611, 463. (e) Han, L.; Zhang, C.; Yazawa, H.; Shimada, S. J. Am.
Chem. Soc. 2004, 126, 5080. (f) Cao, C. C.; Frasser, L. R.; Love, J. A.
J. Am. Chem. Soc. 2005, 127, 17614. (g) Ananikov, V. P.; Malyshev, D. A.;
Beletskaya, I. P.; Aleksandrov, G. G.; Eremenko, I. L. AdV. Synth. Catal.
2005, 347, 1993. (h) Ananikov, V. P.; Orlov, N. V.; Beletskaya, I. P.
Organometallics 2006, 25, 1970. (i) Malyshev, D. A.; Scott, N. M.; Marion,
N.; Steven, E. D.; Ananikov, V. P.; Beletskaya, I. P.; Nolan, S. P.
Organometallics 2006, 25, 4462. (j) Ananikov, V. P.; Orlov, N. V.;
Beletskaya, I. P. Organometallics 2006, 25, 1970. (k) Ananikov, V. P.;
Orlov, N. V.; Beletskaya, I. P.; Khrustalev, V. N.; Antipin, M. Y.;
Timofeeva, T. V. J. Am. Chem. Soc. 2007, 129, 7252.
Scheme 2. Proposed Mechanisms for the M-Catalyzed
Addition of 1 to 2
(6) Ishiyama, T.; Nishijima, K.; Miyaura, N.; Suzuki, A. J. Am. Chem.
Soc. 1993, 115, 7219.
(7) Hua, R.; Takeda, H.; Onozawa, S.; Abe, Y.; Tanaka, M. J. Am. Chem.
Soc. 2001, 123, 2899.
(8) Han, L.-B.; Tanaka, M. J. Am. Chem. Soc. 1998, 120, 8249.
(9) (a) Toyofuku, M.; Fujiwara, S.; Kuniyasu, H.; Kambe, N. J. Am.
Chem. Soc. 2005, 127, 9706. (b) Kuniyasu, H.; Kato, T.; Asano, S.; Ye,
J.-H.; Ohmori, T.; Morita, M.; Hiraike, H.; Fujiwara, S.; Terao, J.; Kurosawa,
H.; Kambe, N. Tetrahedron Lett. 2006, 47, 1141. (c) Knapton, D. J.; Meyer,
T. Y. J. Org. Chem. 2005, 70, 785. (d) Knapton, D. J.; Meyer, T. Y. Org.
Lett. 2004, 6, 687.
(10) (a) Kuniyasu, H.; Kurosawa, H. Chem.-Eur. J. 2002, 2660. (b)
Sugoh, K.; Kuniyasu, H.; Sugae, T.; Ohtaka, A.; Takai, Y.; Tanaka, A.;
Machino, C.; Kambe, N.; Kurosawa, H. J. Am. Chem. Soc. 2001, 123, 5108.
(c) Hirai, T.; Kuniyasu, H.; Kambe, N. Tetrahedron. Lett. 2005, 46, 117.
(d) Hirai, T.; Kuniyasu, H.; Kambe, N. Chem. Lett. 2004, 33, 1148. (e)
Hirai, T.; Kuniyasu, H.; Terao, J.; Kambe, N. Synlett 2005, 1161. (f)
Kuniyasu, H.; Yamashita, F.; Hirai, T.; Ye, J.-H.; Fujiwara, S.; Kambe, N.
Organometallics 2006, 25, 566. (g) Yamashita, F.; Kuniyasu, H.; Terao,
J.; Kambe, N. Org. Lett. 2008, 10, 101.
(11) Hua, R.; Takeda, H.; Onozawa, S-y.; Abe, Y.; Tanaka, M. Org.
Lett. 2007, 9, 263.
(12) Han, L.-B.; Tanaka, M. Chem. Lett. 1999, 863.
(13) (a) Kuniyasu, H.; Ogawa, A.; Miyazaki, S.; Ryu, I.; Kambe, N.;
Sonoda, N. J. Am. Chem. Soc. 1991, 113, 9796. (b) Gareau, Y.; Orellana,
A. Synlett 1997, 803. (c) Kondo, T.; Uenoyama, S.; Fujita, K.; Mitsudo, T.
J. Am. Chem. Soc. 1998, 121, 482. (d) Arisawa, M.; Yamaguchi, M. Org.
Lett. 2001, 3, 763.
(14) For reviews: (a) Kuniyasu, H. In Catalytic Heterofunctionalization;
Togni, A., Gru¨tzmacher, H., Eds.; Wiley-VCH: Zu¨rich, 2001; p 217. (b)
Kondo, T.; Mitsudo, T. Chem. ReV. 2000, 100, 3205. (c) Ogawa, A. Main
Group Metals in Organic Synthsis; Yamamoto, H., Oshima, K., Eds.; Wiley-
VCH: Weinheim, 2004; pp 813. (d) El Ali, B.; Alper, H. In Handbook of
Organopalladium Chemistry for Organic Synthesis; Negishi, E., Ed.; Wiley:
New York, 2002; Chapter VI.6, p 2333. (e) Ogawa, A. In Handbook of
Organopalladium Chemistry for Organic Synthesis; Negishi, E., Ed.; Wiley-
Interscience: New York, 2002; Chaper VII.6. (f) Han, L.; Tanaka, M.
J. Chem. Soc., Chem. Commun. 1999, 395. (g) Ogawa, A. J. Organomet.
Chem. 2000, 611, 463. (h) Beletskaya, I. P. Pure Appl. Chem. 2005, 77,
2021. (i) Beletskaya, I.; Moberg, C. Chem. ReV. 2006, 106, 2320. (j)
Beletskaya, I.; Moberg, C. Chem. ReV. 1999, 99, 3435. (k) Ogawa, A.;
Hirao, T. In Science of Synthesis; Lautens, M., Trost, B. M., Eds.; Georg
Thieme: Stuttgart, 2001; Vol. 1, p 389. (l) Takacs, J. M.; Vayalakkada, S.;
Jiang, X. In Science of Synthesis; Lautens, M., Trost, B. M., Eds.; Georg
Thieme: Stuttgart, 2001; Vol. 1, p 265. (m) Takacs, J. M.; Jiang, X.;
Vayalakkada, S. In Science of Synthesis; Lautens, M., Trost, B. M., Eds.;
Georg Thieme: Stuttgart, 2001; Vol. 1, p 63. (n) Lautens, M. In Science of
Synthesis; Lautens, M., Trost, B. M., Eds.; Georg Thieme: Stuttgart, 2001;
Vol. 1, p 1. (o) Kondo, T. J. Synth. Org. Chem. Jpn. 2001, 59, 170. (p)
Ogawa, A. J. Organomet. Chem. 2000, 611, 463. (q) Ogawa, A.; Sonoda,
N. J. Synth. Org. Chem. Jpn. 1996, 894. (r) Ogawa, A.; Sonoda, N. J. Synth.
Org. Chem. Jpn. 1993, 51, 815.
Similar reaction mechanisms have been proposed for these
addition reactions (Scheme 2). The oxidative addition of 1 to
the M(0) complex can trigger a reaction to provide complex 4
with an ArS-M-G fragment (step A).16 Two pathways are
possible for the following insertion of alkyne 2 (step B): One
is a cis-insertion into the S-M bond of 4 to give
M[C(H)dC(SAr)(R)](G) (5), and the other is a cis-insertion into
the M-G bond of 4 to afford M[C(R)dC(G)(H)](SAr) (6).
Finally, G-C or S-C bond-forming reductive elimination
produces (Z)-(ArS)(R)CdC(G)(H) (3) with regeneration of M
(step C).17-19 Sufficient evidence has been provided for step
A.5,7,8,10-13,20 However, information about steps B and C is very
limited, in part because reductive elimination is faster than
insertion.21,22 For instance, Tanaka et al. reported that the
(17) For C-C bond-forming reductive elimination from Pd(II) com-
plexes, see: (a) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G.
Principle and Application of Organotransition Metal Chemistry, 2nd ed.;
University Science Books: Mill Valley, CA, 1987; p 322. (b) Stille, J. K.
Pure Appl. Chem. 1985, 57, 1771. (c) Stille, J. K. Angew. Chem., Int. Ed.
Engl. 1986, 25, 508. (d) Trost, B. M. In ComprehensiVe Organic Synthesis;
Pergamon Press: New York, 1991; Vol. 3, p 435.
(18) For C-S bond-forming reductive elimination from Pd(II) com-
plexes, see:(a) Mann, G.; Baranano, D.; Hartwig, J. F.; Rheingold, A. L.;
Guzei, I. A. J. Am. Chem. Soc. 1998, 120, 9205. (b) Baranano, D.; Hartwig,
J. F. J. Am. Chem. Soc. 1995, 117, 2937. (c) Kondo, T.; Mitsudo, T. Chem.
ReV. 2000, 100, 3205.
(19) The σ-bond metathesis between either 5 or 6 and 1 can also
afford 3.
(20) (a) Keskinen, A. E.; Senoff, C. V. J. Organomet. Chem. 1972, 37,
201. (b) Ugo, R.; La Monica, G.; Cenini, S. J. Chem. Soc. A 1971, 522. (c)
Zanella, R.; Ros, R.; Graziani, M. Inorg. Chem. 1973, 12, 2736.
(21) (a) Ananikov, V. P.; Beletskaya, I. P.; aleksandrov, G. G.;
Eremenko, I. L. Organometallics 2003, 22, 1414. (b) Ananikov, V. P.;
Kabeshov, M. A.; Beletskaya, I. P; Khrustalev, V. N.; Antipin, M. Y.
Organometallics 2005, 24, 1275.
(15) Cui, Q.; Musaev, D. G.; Morokuma, K. Organometallics 1998, 17,
1383.
(16) The ligand exchange between ArSH and Pd(OAc)2 generates
[Pd(SAr)2]n as an active catalyst for the palladium-catalyzed hydrothiolation
of alkyne.5
(22) The DFT study on the mechanism of Pd-catalyzed thioboration (G
) 9-BBN6) of 2 proposed that 6 is yielded through bond metathesis between
an S-B bond and an alkyne-coordinated C-Pd bond; see ref 15.

4790 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
Scheme 3. Pryridine-Catalyzed Synthesis of 726
reaction of trans-Pd(SPh)(CO2Me)(PCy3)2 (4a) with 1-octyne
produced (Z)-(PhS)(n-C6H13)CdC(CO2Me)(H) (3a), the product
of the Pd-catalyzed addition of PhSC(O)(OMe) to 1-octyne,7
which indicates that C-C17 or S-C18 bond-forming reductive
elimination from a vinyl palladium intermediate facilely pro-
ceeds after the insertion of 1-octyne into either the S-Pd or
the C-Pd bond of 4a. Accordingly, to clarify step B, the
reaction system must be suitably designed to prevent reductive
elimination.23,24
We predicted that Pt(SAr)(Cl)(PPh3)2 (7) would be an ideal
complex for examining the insertion of 2 into the S-M bond,
as we expected that the C-Cl bond-forming reductive elimina-
tion from the vinyl platinum species produced by insertion was
a thermodynamically unfavorable process.25 Furthermore, we
recently developed a general method for the preparation of 7
using pyridine as a catalyst for cis-to-trans isomerization
(Scheme 3).26 Herein we report the details of the insertion of
alkyne into the S-Pt bond of 7, Pt(SAr)2(PPh3)2 (8), and
Pt(SAr)(Ar′)(dppe) (9). The application of successive insertions
of 2 into each S-Pt bond of 8 in the Pt-catalyzed dimerization-
bisthiolation of alkyne (2) by disulfide (30) is also presented.27
Figure 1. ORTEP diagram of trans-Z-10a (Ph on PPh3 omitted).
carried out on a preparative scale (0.06 mmol each at 100 °C
for 14 h), and its structure was determined by X-ray crystal-
lography. The double bond in 10a has a Z-configuration with
the ArS group at the internal position and Pt at the terminal
position (Figure 1),30,31 which provides the definitive evidence
for the insertion of a terminal alkyne 2 into the bond between
a PR3-ligated group 10 metal and a sulfur atom.
Results and Discussion
Insertion of Alkyne (2) into S-Pt Bond(s) of the PPh3-
Ligated Pt(II) Complex. Insertion of 2 into the S-Pt Bond
of trans-Pt(SAr)(Cl)(PPh3)2 (7). The reactions of trans-
Pt(SC6H4Cl-p)(Cl)(PPh3)2 (7a, 0.01 mmol) with phenylacetylene
1
(2a) in toluene-d8 (0.6 mL) at 110 °C were monitored by H
and 31P NMR spectroscopies using SdP(C6H4Me-p)3 as an
internal standard (eq 1).28 The 1H NMR spectra indicated clean
formation of the vinyl platinum complex 10a on the basis of a
signal at δ 7.62 (t, 3JP-H ) 4.0 Hz) assigned to a vinyl hydrogen
atom.29 The 31P NMR signal of 10a appeared at δ 23.6 (s, JPt-P
) 3021 Hz). The yield reached 83% after 6 h. Compound 10a
was isolated by recrystallization in 87% yield from a reaction
It should be noted that the configuration and substitution
pattern of 10a are in agreement with the structure of 5 in Scheme
2. Similar insertions were confirmed for the reactions of 1-octyne
(2b) and propargyl alcohol (2c): The corresponding vinyl
platinum complexes 10b (only trans) and 10c (only trans) were
obtained in 87% and 69% yield after 16 and 6 h, respectively.
The observation that no alkyne-exchange reaction took place
after the treatment of trans-Pt[(Z)-C(H)dC(SC6H4Cl-o)(Ph)]-
(Cl)(PPh3)2 (Vide infta) with 1-octyne (2b) even after 6 h at 70
°C suggests that the insertion step is an irreversible process. In
agreement with the previous findings that internal alkynes are
generally inert in addition reactions of ArS-G (1) to 2 with PR3-
ligated Pd or Pt catalysts, no insertion took place with 4-octyne.
However, it was found that ethyl phenylpropiolate (2d; R )
Ph, R′ ) C(O)OEt) exhibits quite high reactivity toward the
insertion: The 31P NMR spectroscopy of the reaction mixture
of 2d with 7a taken after 30 h indicated the formation of vinyl
platinum complex 10d in 96% yield on the basis of a signal at
δ 23.3 (s, JPt-P ) 3044 Hz). The reaction of 7a with 1-phenyl-
3-methoxy-1-propyne (2e; R ) Ph, R′ ) CH2OMe) under the
same reaction conditions afforded a similar vinyl platinum, 10e,
(23) The insertions of activated 2 into S-M (M ) Mo, Co, Ru, W, Fe,
Rh, Ir, and Ru) bonds have been reported:(a) Halbert, T. R.; Pan, W. H.;
Stiefel, E. I. J. Am. Chem. Soc. 1983, 105, 5476. (b) Carlton, L.; Bakar,
W. A. W. A.; Davidson, J. L. J. Organomet. Chem. 1990, 394, 177. (c)
Davidson, J. L.; Sharp, D. W. A. J. Chem. Soc., Dalton Trans. 1975, 2283.
(d) Koelle, U.; Rietmann, C.; Tjoe, J.; Wagner, T.; Englert, U. Organo-
metallics 1995, 14, 703. (e) Petillon, F. Y.; Floch-Perennou, F. L.; Guerchais,
J. E.; Sharp, D. W. A. J. Organomet. Chem. 1979, 173, 89. (f) Herberhold,
M.; Yan, H.; Milius, W.; Wrackmeyer, B. Chem.-Eur. J. 2000, 6, 3026,
and references therein. (g) Misumi, Y.; Seino, H.; Mizobe, Y. J. Organomet.
Chem. 2006, 691, 3157.
(24) The successive insertion into a S-Pd bond and following reductive
elimination were indicated by the reaction of Pd(SAr)2(dppe) with DMAD
(dimethyl acetylenedicarboxylate): Sugoh, K.; Kuniyasu, H.; Kurosawa, H.
Chem. Lett. 2002, 106.
(25) (a) Rajaram, J. R.; Pearson, R. G.; Ibers, J. A. J. Am. Chem. Soc.
1974, 96, 2103. (b) Furlani, A.; Russo, M. V.; Villa, A. C.; Manfredotti,
A. G.; Guastini, C. J. Chem. Soc., Dalton Trans. 1977, 2154.
(26) Yamashita, F.; Kuniyasu, H.; Terao, J.; Kambe, N. Inorg. Chem.
2006, 45, 1399.
(27) Apartofthepresentstudyhasbeenreportedincommunications:Kuniyasu,
H.; Yamashita, F.; Terao, J.; Kambe, N. Angew. Chem., Int. Ed. Engl. 2007,
46, 5929. See also refs 10b and 10g.
(28) No interaction between SdP(C6H4Me-p)3 and other reagents has
been confirmed during the course of the present study.
(29) Stang, P. J.; Zhong, Z.; Kowalski, M. H. Organometallics 1990,
9, 833.
(30) In the following discussion, cis and trans refer to the relationship
of the two PPh3 groups at a Pt center; E and Z refer to the configuration of
the double bond of a vinyl substituent.
(31) Crystal data for trans-Z-10a: space group P21/c (#14), a ) 12.731(2)
Å, b ) 10.829(2) Å, c ) 33.907(5) Å, ꢀ ) 92.26(1)°, Z ) 4, R ) 0.046,
Rw ) 0.113.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4791
Table 1. Effects of Substituents in Arylacetylenea
entry
X
2
τ1/2 (h)
1
2
3
4
5
6
7
8
9
p-CF3
p-Cl
p-F
2f
10.2
7.6
6.4
6.3
5.4
3.8
2.7
13.1
7.0
2g
2 h
2a
2i
H
m-Me
p-Me
p-OMe
o-Cl
2j
2k
2l
Figure 2. ORTEP diagram of trans-Z-10d (Ph on PPh3 omitted).
o-Me
2m
a trans-7b (0.01 mmol) and 2 (0.17 M) in C6D6 at 70 °C.
The effects of substituent X of Pt(SC6H4X)(Cl)(PPh3)2 (7) toward
insertion of PhCt CH (2a) (0.17 M) at 70 °C were examined next
(Table 2). The consumption rate of starting trans-7 obeyed pseudo-
first-order kinetics, and the values of the half-lives (τ1/2) range from
τ1/2 ) 12.2 h for the platinum complex with a p-CF3 group (7c) to
τ1/2 ) 2.8 h with a p-OMe substituent (7f) for the para substituents
(entries 1-5). The Hammett plot shows a fairly good linear free-
energy relationship with simple σ values (Figure 5). Its negative
slope (F ) -0.7) also indicates that EDGs slightly facilitate the
insertion reaction. Hartwig et al. have reported that a similar
electronic effect was detected for C-S bond-forming reductive
elimination from a Pd(II) complex.18a,b Considering that the alkyne-
coordinated complex 11 has a platinacyclopropene character (12),
EDGs in the ArS group may similarly promote the migration of
an ArS group toward the coordinated alkyne moiety. On the other
hand, a slight increase in reaction rate, by introducing EDG in
XC6H4Ct CH (Figure 4), may be attributed to the facilitation of
the coordination of an alkyne to a coordinatively unsaturated
platinum(II) complex produced after liberation of PPh3. The
reaction was retarded significantly in the presence of additional
PPh3 (3 equiv) (τ1/2 ) 16.4 h; Table 2, entry 6). The τ1/2 value of
10.1 h observed for 7g with an o-Me substituent (entry 7) and the
Figure 3. ORTEP diagram of trans-Z-10e (Ph on PPh3 omitted).
in 82% yield. The structures of 10d and 10e were both
unambiguously determined by X-ray crystallographic analyses,
proving that the double bonds of the vinyl platinums have a
Z-configuration with Pt at the R-carbon of either the CO2Et or
the CH2OMe groups (Figures 2 and 3).32 It is noteworthy that
the Pt-O distances of 10d (3.0 Å) and 10e (3.0 Å) are both
within the sum of the van der Waals radii (3.2 A) of the two
atoms, implying that the interaction between the Pt and O atoms
plays a crucial role in achieving regioselective insertion of 2d
and 2e into the S-Pt bond of 7. The effects of substituents in
XC6H4Ct CH were then examined under the conditions of 0.01
mmol of trans-Pt(SC6H4Br-p)(Cl)(PPh3)2 (7b) and 0.17 M 2 in
C6D6 at 70 °C. The consumption rate of trans-7b obeyed
pseudo-first-order kinetics: The half-life (τ1/2) of trans-7b for
each reaction is shown in Table 1. The values range from τ1/2
τ
1/2 value of 13.3 h with an o-Pr-i group (7h, entry 8) suggest that
the steric hindrance caused by the substituent in the ortho position
retards the insertion similarly to the ortho substituents in arylacety-
lene derivatives (entries of 8 and 9 of Table 1). Intriguingly, a τ1/2
value of 0.28 h was observed for o-Cl-substituted 7i: The reaction
was approximately 19 times faster than that of the complex with
a PhS group (entries 3 and 9). Whereas similar facilitation of the
insertion step was observed with an o-Br substituent (τ1/2 ) 0.26 h;
the insertion proceeds approximately 20 times faster than that of
) 10.2 h for a p-CF3-substituted arylacetylene (2f) to τ1/2
)
the complex with PhS; entry 10) and an o-I substituent (τ1/2
)
2.7 h for a p-OMe-substituted arylacetylene (2k) (entries 1-7).
0.19 h; the insertion proceeds approximately 28 times faster than
that of the complex with PhS; entry 11), the insertion was
suppressed with an o-F substituent (τ1/2 ) 7.3 h; 1.4 times slower
that of the complex than with PhS; entry 12). Thus, we could
conclude that the high-energy lone pairs of electrons at the ortho
position are required to facilitate the insertion step. On the other
In comparison with simple σ values, the Hammet plot shows
a better linear free-energy relationship with σ+ values that
correlate with the acidity of the equivalently substituted benzoic
acids (Figure 4). A small negative slope (F ) -0.4) shows that
electron-donating groups (EDGs) slightly facilitate the reaction.
The τ1/2 value of 13.1 h observed for 2l with an o-Cl substituent
(entry 8) and τ1/2 value of 7.0 h with an o-Me group (entry 9)
indicate that the steric hindrance caused by the substituent in
the ortho position of XC6H4Ct CH retards the insertion.
hand, no large differences were observed between p-OMe (τ1/2
)
2.8 h; entry 5) and o-OMe (τ1/2 ) 1.5 h; entry 13) substituents:
We postulate that steric retardation and a certain degree of electronic
facilitation by the o-OMe group cancel each other out.
(32) Crystal data for trans-Z-10d: space group P21/n (#14), a )
12.1258(2) Å, b ) 12.6125(3) Å, c ) 34.5793(7) Å, ꢀ ) 100.5756(7)°, Z
) 4, F ) 1.54 g/cm3, R ) 0.040, and Rw ) 0.085. Crystal data for trans-
Z-10e: space group Pna21/n (#33), a ) 39.9145(7) Å, b ) 11.9216(3) Å,
c ) 9.4584(2) Å, ꢀ ) 101.6122(9)°, Z ) 4, F ) 1.542 g/cm3, R ) 0.040,
and Rw ) 0.118.

4792 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
Figure 4. Hammett plot for the reaction rates of insertion of 2a and 2f-2k into the S-Pt bond of trans-7b.
Table 2. Effects of Substituents in ArS of 7a
Scheme 4
entry
X
7
τ1/2 (h)
entry
X
7
τ1/2 (h)
1
2
3
4
p-CF3
p-Cl
H
p-Me
p-OMe
p-Me
o-Me
7c
7a
7d
7e
7f
7e
7g
12.2
6.1
5.3
4.0
2.8
8
9
10
11
12
13
o-Pr-i
o-Cl
o-Br
o-l
o-F
o-OMe
7 h
7i
7j
7k
7 l
7m
13.3
0.28
0.26
0.19
7.3
Scheme 5
Scheme 6
5
6b
7
16.4
10.1
1.5
a 7 (0.01 mmol), 2a (0.17 M) in C6D6 at 70 °C. b PPh3 (0.03 mmol)
was added.
similar ligand exchange with complexes 7i and 7i′, which
contain an o-Cl substituent, took place at a slightly lower
reaction rate (12% yield of 7i′′ after 1 h). These results may
rule out the possibility that the dissociation of one phosphine
ligand triggered by the coordination of o-X (X ) Cl, Br, or I)
to Pt (13 in Scheme 4) promotes the insertion of an alkyne into
the S-Pt bond. Another possibility is that the o-halogen
coordinates to the vacant site generated by the migration of ArS
to the alkyne (14 in Scheme 5).35 It is also possible that one of
the electron lone pairs on X interacts with the S-Pt σ* orbital
and thus weakens the S-Pt bond (15 in Scheme 6). In fact,
X-ray crystallographic analysis of trans-Pt(SC6H4Br-o)(Cl)(P-
Ph3)2 (7j) showed that the Br-S distance of 3.2 Å is within the
sum of the van der Waals radii (3.6 Å) of the two atoms (Fig-
ure 6). We have already reported that the efficiency of
thiocarbamoylation of terminal alkyne (2) by sulfenamide
(ArSNR2) and CO was significantly improved by introducing
2,4,5-tri-Cl substituents in Ar (eq 3).9b This may be attributed
to the present “o-halogen effect” under alkyne insertion into
the S-Pd bond.
Figure 5. Hammett plot of the rates of IS of 2a into the S-Pt
bond of 7a and 7c-7f.
We next sought to elucidate the mechanism underlying the
observed “o-halogen effect”. Intramolecular coordination by
o-halogen substituents in ligands of the type ArS has previously
been documented.33,34 Thus, we carried out a phosphine-ligand-
exchange reaction to determine whether an o-halogen substituent
accelerates the liberation of PPh3 (eq 2). The treatment of trans-
Pt(SC6H4Cl-p)(Cl)(PPh3)2 (7a) with trans-Pt(SC6H4Cl-p)-
(Cl)[P(C6H4Me-p)3]2 (7a′) at 25 °C gave trans-Pt(SC6H4Cl-p)-
(Cl)(PPh3)[P(C6H4Me-p)3] (7a′′) in 23% yield after 1 h. A
(33) Catala, R. M.; Cruz-Garritz, D.; Hills, A.; Hughes, D. L.; Richards,
R. L.; Sosa, P.; Torrens, H. J. Chem. Soc., Chem. Commun. 1987, 261. (b)
Davis, J. A.; Davie, C. P.; Sable, D. B.; Armstrong, W. H. Chem. Commun.
1998, 1649. (c) Kulawiec, R. J.; Crabtree, R. H. Coord. Chem. ReV. 1990,
99, 89.
Insertion of 2 into the S-Pt Bond of Pt(SAr)2(PPh3)2
(8). Insertion under Thermal Conditions. When the reaction
of trans-Pt(SC6H4Br-p)2(PPh3)2 (8a) (0.01 mmol) with 1-octyne
(34) Intramolecular coordination of a ꢀ-cis-SAr group of an R,ꢀ-
unsaturated acyl platinum and palladium complexes facilitated decarbony-
lation: Kato, T.; Kuniyasu, H.; Kajiura, T.; Minami, Y.; Ohtaka, A.;
Kinomoto, M.; Terao, J.; Kurosawa, H.; Kambe, N. Chem. Commun. 2006,
868.
(35) Assistance through the intramolecular coordination of an OH group
has been reported on the basis of a molecular-orbital study of the insertion
of an alkyne into a B-Pt bond: Cui, Q.; Musaev, D. G.; Morokuma, K.
Organometallics 1997, 16, 1355.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4793
(R)(ArS)CdC(H)(SAr) was not detected at all.13 While signals
of 16a, 16a′, and 17a disappeared after 40 h, the yields of 18a
and 19a reached 78% and 93%, respectively. This result clearly
demonstrates the advantage of the use of trans-Pt(SAr)(Cl)(P-
Ph3)2 (trans-7) for the clear-cut investigation of insertion of an
alkyne into a S-Pt bond, because the starting complex Pt(SAr)-
(Cl)(PPh3)2 (7) and the product of vinyl platinum Pt[(Z)-
C(H)dC(SAr)(R)](Cl)(PPh3)2 (10) were both tolerant of the
formation of either S- or Cl-bridging complexes. This is
presumably attributed to the lower basicities of lone pairs of S
and Cl atoms of 7 and 10 compared to those of lone pairs of S
atoms of 8 and 16. The formation of 18a and 19a was
rationalized by postulating that another 2b is inserted into the
remaining S-Pt bond of 16 to give the bisvinyl platinum
complex 20a (not detected), which undergoes C-C bond-
forming reductive elimination to produce 19 and the Pt(0)
complex.38 The “o-halogen effect” was next studied with the
trans and cis dithiolate complexes of Pt(SAr)2(PPh3)2 (Ar )
C6H4Cl-o, 8b), both of which were selectively prepared.39 The
treatment of trans-8b with 10 equiv of phenylacetylene (2a) at
25 °C furnished the vinyl platinum complex 16b in 40% yield
(only cis) after 4 h and 95% yield (cis/trans ) 85/15) after 55 h
(eq 5).36,40 In stark contrast, 16b was not formed at all when
cis-8b was treated with 2a for 4 h under the same reaction
conditions (eq 6). The higher reactivity of trans-8b relative to
that of cis-8b toward the insertion of an alkyne may be attributed
to the stronger trans effect of PPh3 in trans-8b than that of SAr
in cis-8b to liberate PPh3.41
Figure 6. ORTEP diagram of 7j. Selected bond lengths [Å]: Pt-S
2.319(2), Br-S 3.202 (2).
(2b) (0.4 M) was conducted at 80 °C in C6D6 (0.5 mL) in the
presence of additional PPh3 (0.02 mmol), the formation of vinyl
platinum cis-Pt[(Z)-C(H)dC(SC6H4Br-p)R](SC6H4Br-p)(PPh3)2
(R ) C6H13-n, 16a),36 a product of insertion of 2b into the S-Pt
bond of 8a, was confirmed in 29% yield (cis/trans ) 15/85)
after 1 h by 31P NMR spectroscopy (eq 4). Signals suspected
as S-bridging complexes such as Pt[(Z)-C(H)dC(SC6H4Br-p)-
(R)](PPh3)(µ-SAr)2Pt[(Z)-C(H)dC(SC6H4Br-p)(R)](PPh3) (16a′)
and Pt[(Z)-C(H)dC(SC6H4Br-p)(R)](PPh3)(µ-SAr)2Pt(SC6H4-
Br-p)(PPh3) (17a) were confirmed in 16% (syn/anti ) 31/69)
and 5% (40/60) yields, respectively, after 8 h.37 The signals of
Pt(PhCt CH)(PPh3)2 (18a) and (Z,Z)-(p-BrC6H4S)(R)CdC(H)-
C(H)dC(SC6H4Br-p)(R) (19a) were also detected in 28% and
35% yields, respectively. It must be noted that (Z)-
(36) Authentic samples of 16 were synthesized by either oxidative
addition of (Z)-(ArS)(R)CdC[C(O)SAr](H) to Pt(PPh3)2(C2H4) and the
following decarbonylation34 or the oxidative addition of (Z)-(ArS) -
(R)CdC(SAr)(H) to Pt(PPh3)2(C2H4): Kuniyasu, H.; Ohtaka, A.; Nakazono,
T.; Kinomoto, M.; Kurosawa, H. J. Am. Chem. Soc. 2000, 122, 2375.
(37) Treatment of a solution of authentic 16a at elevated temperature
produces 16a′ and an equivalent amount of liberated PPh3. Complex 17a
Insertion under Photoirradiated Conditions. For the
insertion of phenylacetylene (2a) into the H-Pt bond of trans-
was also generated by the stoichiometric reaction of 16a with trans-8a.34
.

4794 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
Scheme 7. Photo- and Thiol-Driven trans-Insertion of
Phenylacetylene (2a) into the H-Pt Bond of trans-Pt(H)(X)-
(PPh3)2 (21)42
Pt(H)(X)(PPh3)2 (21, X ) SAr, Cl, Br, and I), we have reported
that unconventional trans-insertion proceeds under photo- and
thiol-driven reaction conditions to afford cis-Pt[(Z)-C(H)d
C(Ph)(H)](PPh3)2 (22) in good yields (Scheme 7).42 Thus, we
next examined the effects of photoirradiation under the insertion
of 2 into the S-Pt bonds of 7 and 8.
of 0.01, 0.02, and 0.1 mmol of additional PPh3, respectively
(entries 3-5).44
Under photoirradiation, complex 8a existed as a mixture of
stereoisomers from the early stage of the reaction of 2n with
8a (cis/trans ) 20/80 after 10 min starting from trans-8a) (entry
1). In order to specify which stereoisomer of 8a underwent the
insertion of 2n, trans-8a and cis-8a39 were treated with 100
equiv of 2n under 30 s of photoirradiation (entries 6 and 7).
The former reaction produced 2.4% cis-Z-16c (with remaining
cis-8a/trans-8a ) 1/99), while the latter did not produce any
detectable amount of insertion product (cis-8a/trans-8a ) 81/
19); these facts demonstrate that trans-8a is much more reactive
than cis-8a under photoirradiated insertion, which is a scenario
that is similar to thermal insertion (eqs 5 and 6). Dimeric
complex anti-[Pt(SAr)2(PPh3)]2 (anti-8a′), which is thermody-
namically more stable than monomeric 8a,45 showed no activity
for the insertion of 2n under a photoirradiated reaction (entry
8). Because the reaction of trans-8a with 1 equiv of 2n afforded
19% 8a′ together with 25% Z-16c by 2 h of photoirradiation
(entry 9), an excess amount of 2n relative to trans-8a was
indispensable for attaining the clean formation of 16c by the
reaction of trans-8a with 2n.
Next, to determine which wavelength of light facilitates the
insertion reaction of 2n into the S-Pt bond of trans-8a,
photoirradiation was performed using filters to cut a certain
range of wavelength of light. The reactions carried out under
the irradiation of light with a wavelength of >330 and >430
nm gave 91% (cis/trans ) 83/17) and 83% (only cis) Z-16c
after 1 h, respectively (entries 10 and 11). In marked contrast,
no reaction took place under the irradiation of >540 nm light
(entry 12). These results clearly showed that light in the range
of approximately 300 to 500 nm effectively induces the clean
conversion of 2n and trans-8a into cis-Z-16c.46,47 Examples of
the present photoinduced insertion using other alkynes 2 are
shown in eq 7. Insertion with phenylacetylene (2a) furnished
cis-Z-16d as a kinetic product (15%, only cis after 10 min),
which gradually isomerized to the E-isomer during the course
of the reaction (98% cis-10d with E/Z ) 17/83 after 1 h).
Insertion of 1-octyne (2b) into the S-Pt bond of trans-8a also
proceeded to furnish the corresponding vinyl platinum Z-16a
in 87% yield (cis/trans ) 97/3) after 1 h. Similar treatment of
sterically more hindered 3,3-dimethyl-1-butyne (2o) yielded cis-
Z-16e, albeit somewhat sluggishly (69% after 1 h). Attempted
reactions with internal alkynes such as 4-octyne and dipheny-
First, a C6D6 (0.5 mL) solution of trans-Pt(SPh)(Cl)(PPh3)2
(7d, 0.01 mmol) and PhCt CH (2a, 0.1 mmol) placed in a Pyrex
NMR tube, which was soaked in a cooled water bath (25 °C),
was irradiated using a 500 W tungsten lamp. The reaction was
1
monitored by H and 31P NMR spectroscopies. After 1 h, the
formation of 20% cis-7d and 4% (cis/trans ) 24/76)
Pt(SAr)2(PPh3)2 (8c) was confirmed, respectively: Isomerization
and disproportionation of trans-7b are induced by photoirra-
diation. However, no formation of the corresponding vinyl
platinum 10 was detected. In marked contrast, regio- and
stereoselective cis-insertion of alkyne 2 into the S-Pt bond of
8 was remarkably promoted with the aid of photoirradiation:
The effect of photoirradiation was scrutinized by the reaction
of methyl propargyl ether (2n) (0.1 mmol) with Pt(SAr)2(PPh3)2
(Ar ) p-Br; 8a) (0.01 mmol) in C6D6 (0.5 mL) carried out in
a Pyrex NMR tube at 25 °C (Table 3). Irradiation of the solution
of trans-8a and 2n by a 500 W tungsten lamp for 10 min
resulted in the selective formation of a cis-platinum complex
(cis-Z-16c)36 in 14% yield. After 1 h of photoirradiation, the
yield of 16c reached 91% with cis/trans ) 83/17 (entry 1). Once
the isolated cis-Z-16c isomerized into E-16c under photoirra-
diation (trans-Z-16c (16%), cis-E-16c (10%), and trans-E-16c
(8%) in C6D6 after 5 h), cis-Z-16c was also formed as a kinetic
product of insertion of 2n into the S-Pt bond of 8a: Both stereo-
and regiochemistry of 16 were in agreement with the structure
of vinyl platinum complex produced under thermal conditions
(eq 5). Accordingly, photoirradiation promotes regio- and
stereoselective cis-insertion of an alkyne into the S-Pt bond
as well as trans-insertion of an alkyne into the H-Pt bond
(Scheme 8).
On the other hand, the samples of 8a and 2n left in the dark
at 25 °C furnished no 16c, even after 5 days (entry 2).43 The
insertion was significantly retarded by the addition of PPh3:
Z-16c was produced in 28%, 19%, and 5% yields in the presence
(38) For C-C bond-forming reductive elimination from Pt(II) com-
plexes, see:(a) Stang, P. J.; Kowalski, M. H. J. Am. Chem. Soc. 1989, 111,
3356. (b) Merwin, R. K.; Schnabel, R. C.; Koola, J. D.; Roddick, D. M.
Organometallics 1992, 11, 2972, and references therein.
(39) The configurations of trans-8 and cis-8 were independently
identified by X-ray crystallographic analysis: Lai, R. D.; Shaver, A. Inorg.
Chem. 1981, 20, 477.
(40) The reaction of 2a with trans-Pt(SC6H4Cl-p)(Cl)(PPh3)2 (7i) under
similar reaction conditions did not take place at all.
(41) (a) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem.
ReV. 1973, 10, 335. (b) Chan, L. T.; Chen, H.-W., Jr.; Masters, A. F.; Pan,
W.-H. Inorg. Chem. 1982, 21, 4291. (c) Tu, T.; Zhou, Y.-G.; Hou, X.-L.;
Dai, L.-X.; Dong, X.-C.; Yu, Y.-H.; Sun, J. Organometallics 2003, 22, 1255.
(42) Ohtaka, A.; Kuniyasu, H.; Kinomoto, M.; Kurosawa, H. J. Am.
Chem. Soc. 2002, 124, 14324.
(43) The sample has to be strictly shielded to suppress the insertion
because Z-16c was formed in 40% yield after 48 h with the sample placed
under fluorescent light.
(44) Neither the generation of a new peak nor peak change of 8c was
observed by the addition of PPh3. This could rule out the possibility that
the retardation was caused by forming the five-ligand-coordinated platinum
complex.
(45) Kuniyasu, H.; Sugoh, K.; Moon, S; Kurosawa, H. J. Am. Chem.
Soc. 1997, 119, 4669.
(46) Because cis-Z-16c hardly absorbs >430 nm light, the cis-to-trans
isomerization from cis-Z-16c was suppressed under the reaction conditions
of entry 11. See the Supporting Information for the UV-vis spectra of
trans-8a and cis-Z-16c.
(47) When a solution of 2n was treated with trans-8a under the
irradiation of a UV(Hg) lamp (500 W), 8a was consumed within 10 min to
yield 76% 16c (52% of cis-Z, 10% trans-Z, and 14% cis-E) together with
undetermined byproducts.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4795
Table 3. Effect of Photoirradiation on the Reaction of 2n with 8a (8a′)a
entry
1
8
time
10 minc
1 h
5 days
1 h
1 h
yield of Z-16c (%)b
entry
7j
8
time
30 s
yield of Z-16c (%)b
trans-8a
14d
91e
0
cis-8a
0l
2f
3g
4h
5i
6j
trans-8a
trans-8a
trans-8a
trans-8a
trans-8a
8i
9n
anti-8a′
trans-8a
trans-8a
trans-8a
trans-8a
2 h
2 h
1 h
1 h
1 h
0m
28
19
5
25eo
91e
83d
0
10p
11q
12r
1 h
30 sk
2.4d
a Unless otherwise noted, 2n (0.1 mmol), 8a (8a′) (0.01 mmol of Pt), and C6D6 (0.5 mL) in a Pyrex NMR tube were irradiated by a 500 W tungsten
lamp at 25 °C. b Determined by 1H and 31P NMR. c cis-8a/trans-8a ) 20/80. d Only cis-Z. e cis/trans ) 83/17. f Under dark. g 0.01 mmol of PPh3 was
added. h 0.02 mmol of PPh3 was added. i 0.1 mmol of PPh3 was added. j 2a (0.25 mmol), 8a (0.0025 mmol). k cis-8a/trans-8a ) 1/99. l cis-8a/trans-8a
) 81/19. m syn-8a′/anti-8a′ ) 24/76. n 2a (0.01 mmol). o 19% of 8a′ (syn/anti ) 24/76) was formed. p >330 nm. q >430 nm. r >540 nm.
Scheme 8. Photoassisted trans vs cis Insertion of Alkyne
Table 4. Competitive Insertion between 2a and Substituted
Arylacetylenea
entry
2
X
relative ratio of 16/16d
Figure 7. Free-energy relationship for the insertion of arylacetylene
into Pt-S bond of trans-8d.
1
2
3
4
5
6
7
8
2p
2q
2g
2r
2i
2j
2k
2s
p-CO2Me
m-CO2Me
p-Cl
m-OMe
m-Me
p-Me
p-OMe
p-NH2
16f
0.28
0.17
0.72
1.1
16g
16 h
16i
abundant 2 reacts faster and the effect is greater relative to the
thermal insertion of 2 into the S-Pt bond of Pt(SAr)(Cl)(PPh3)2
(7b) (F ) -0.7 in Figure 4). Furthermore, the quantum yield
of the present photoinduced reaction of trans-8a with 10 equiv
of 2n at 313 nm was calculated to be approximately 0.7 by
using a merry-go-round apparatus with the disappearance of
2-hexanone as a reference.49 To clarify the reason photoirra-
diation facilitates the insertion reaction, a C6D6 solution of trans-
8a was treated with PAr′3 (Ar′ ) C6H4OMe-p, 23) (10 equiv)
(eq 8): The ligand-exchange reaction was dramatically promoted
by photoirradiation to yield 77% Pt(SAr)2(PAr′3)2 (8c) (23/77)
and 15% Pt(SAr)2(PPh3)(PAr′3) (8d) (cis/trans ) 17/83) under
1 h of photoirradiation, whereas no reaction occurred in the
dark under otherwise identical reaction conditions.
16j
16k
16l
1.2
1.6
4.6
16m
4.3
a trans-8a (0.01 mmol) and 2 (0.2 M each) in C6D6 at 25 °C under
1 h of photoirradation.
lacetylene did not take place, as in the case of thermal insertion
into the S-Pt bond of 8.48
To elucidate the electronic effect of 2 for photoirradiated
insertion into the S-Pt bond of trans-8a, the relative reaction
rates between 2a and XC6H4Ct CH having substituents in the
meta and the para position were examined under competitive
reaction conditions (Table 4). The Hammett plot (Figure 7)
roughly showed a linear free-energy relationship with σ values:
Its negative slope (F ) -1.3) suggests that electronically more
The experiments described above suggest the following
reaction pathway leading to the formation of 10 and 16 by the
reactions of 7 and 8 with 2 (Scheme 9): Complex 7 (8) reacts
via complex trans-24, which is formed by the liberation of PPh3,
with alkyne 2 to afford the alkyne complex 25. The alkyne with
high nucleophlicity preferentially coordinates probably due to
the electrophilic character of trans-24. The migration of the ArS
group onto the coordinated alkyne with a Pt bound at either the
(48) (a) The reactivity of DMAD for the insertion into the S-Pt bond
of 8a was not fully revealed because DMAD promptly reacted with PPh3
of 8a: Tebby, J. C.; Wilson, I. F.; Griffiths, D. V. J. Chem. Soc., Perkin
Trans. 1 1976, 2133. (b) Waite, N. E.; Tebby, J. C.; Ward, R. S.; Williams,
D. H. J. Chem. Soc. C 1969, 1100.
(49) Murov, S. L. Handbook of Photochemistry; Marcel Dekker: New
York, 1973; p 207.

4796 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
Scheme 9. Possible Reaction Pathway for Insertion of 2 into
the S-Pt Bond of 7 (8)
sterically less-hindered terminal carbon (R′ ) H) or the carbon
with RO-group substitution (R ) Ph; R′ ) C(O)OEt, CH2OMe)
gives 26. The photoirradiation facilitates the liberation of PPh3
from 8 to form trans-Pt(SAr)2(PPh3) (24, X ) SAr), the
formation of which can be suppressed by the addition of
PPh3.50,51 Coordination of PPh3 at the vacant site results in the
formation of cis-Z-10 (16) as a kinetic product,52 which
isomerizes to the thermodynamically more stable trans-Z-10
(16).
Figure 8. ORTEP diagram of 23a (Ph on DPPE omitted).
Table 5. Effect of Substituent in Ar of Pt(SAr)Ph(DPPE) (9)a
Insertion of Alkyne (2) into S-Pt Bond of dppe-Ligated
Pt(II) Complex. The reactivities of complex Pt(SAr)(Ar′)(dppe)
(9, dppe; Ph2P(CH2)2PPh2) toward alkynes were next examined.
Unlike the cases of reactions with 7 and 8, unactivated alkynes
such as PhCt CH (2a) and 1-octyne (2b) reacted with 9 under
neither thermal nor photoirradiated reaction conditions. In
contrast, DMAD (2t), an electronically deficient alkyne, exhib-
ited high reactivity for the insertion. When the reaction of 2t
(0.1 mmol) with Pt(SC6H4OMe-p)(C6H4OMe-p)(dppe) (9a)
(0.005 mmol) in CD2Cl2 (0.5 mL) at 25 °C was monitored by
31P NMR spectroscopy, the formation of vinyl platinum complex
27a was indicated on the basis of a set of doublets centered at
entry
9
27
Ar
τ1/2 (h)
1
2
3
4
5
6
9b
9c
9d
9e
9f
27b
27c
27d
27e
27f
p-CF3
p-Br
Ph
p-Me
p-OMe
o-Br
11.3
3.5
1.6
0.35
0.34
7.4
9g
27g
a 9 (0.01 mmol) and 2t (0.17 M) in C6D6 at 25 °C.
δ 40.2 (JP-P ) 2.7 Hz, JPt-P ) 2224 Hz) and δ 41.4 (JP-P
)
2.7 Hz, JPt-P ) 1695 Hz) in 90% yield after 1 h (eq 9).53
Compound 27a was isolated by recrystallization in 33% yield
from the reaction carried out on a preparative scale, and its X-ray
crystallographic analysis demonstrated that DMAD inserted into
the S-Pt bond of 9a in a cis-fashion (Figure 8).54 Whereas PPh3-
ligated bisvinyl platinum complex 20 underwent C-C bond-
forming reductive elimination (eq 4), isolated 27a was inert for
reductive elimination even at 60 °C in C6D6.
Table 6. Effect of Substituent in Ar′ of Pt(SC6H4Br-p)(Ar′)(DPPE)
(9)a
entry
9
23
Ar
τ1/2 (h)
1
2
3
4
5
9h
9i
9e
9j
23h
23i
23e
23j
23k
p-CO2Et
p-Cl
Ph
p-Me
p-OMe
5.8
4.4
3.5
3.0
2.5
9k
a 9 (0.01 mmol) and 2t (0.17 M) in C6D6 at 25 °C.
order kinetics, and half-lives (τ1/2) are shown in Tables 5 and
6, respectively. The values range from τ1/2 ) 11.3 h for the
platinum complex with a p-CF3-substituted aromatic ring of ArS
to τ1/2 ) 0.34 h with a p-OMe-substituted aromatic ring (entries
1-5, Table 5). The Hammet plot shows a good linear free-
energy relationship with simple σ values (Figure 9). Its negative
slope (F ) -2.0) indicates that EDGs facilitate the insertion.
The τ1/2 ) 7.4 h for the o-Br-substituted platinum complex 9g
demonstrates that the “o-halogen effect” is not observed for a
dppe-ligated reaction system (entry 6). The Hammet plot about
substituents in the Ar′ of 9 (Table 6, Figure 10) also shows a
good linear free-energy relationship with simple σ values. The
negative slope (σ ) -0.5) indicates that EDGs also promote
insertion, but the effect is more subtle relative to the electronic
effect in ArS. The possible reaction mechanisms for the insertion
of 2t into the S-Pt bond of 9 is depicted in Scheme 10.
Complex 9 can react with 2t to give either cationic platinum
complex 28 or the five-ligand-coordinated platinum complex
To get insight on the mechanism of the insertion, the effects
of substituents in the ArS and Ar′ moieties of Pt(SAr)(Ar′)(dppe)
(9) were then examined in the presence of an excess amount of
2t (0.17 M). The consumption rates of 9 obeyed pseudo-first-
(50) (a) Wrighton, M. S. Chem. ReV. 1974, 74, 401. (b) Geoffroy, G. L.;
Wrighton, M. S. Organometallic Photochemistry; Academic Press: New
York, 1979. (c) Sakakura, T.; Sodeyama, T.; Sakaki, K.; Wada, K.; Tanaka,
M. J. Am. Chem. Soc. 1990, 112, 7221.
(51) For photoirradiated ligand dissociation, see:(a) Wada, M.; Kumazoe,
M. J. Chem. Soc., Chem. Commun. 1985, 1204. (b) Wink, D. A.; Ford,
P. C. J. Am. Chem. Soc. 1986, 108, 4838. (c) Ruiz, J.; Garland, M.; Roman,
E.; Astruc, D. J. Organomet. Chem. 1989, 377, 309.
(52) The cis vinyl platinum complex was also detected as a kinetic
product in the early stages of the reaction of 7j with 2a.
(53) Complex 9 was hardly soluble in C6D6.
j
(54) Crystal data for 27a: space group P1(#2), a ) 12.631(1) Å, b )
17.188(2) Å, c ) 11.455(1) Å, R ) 90.219(4)°, ꢀ ) 114.082(5)°, γ )
107.153(3)°, Z ) 2, F ) 1.518 g/cm3, R ) 0.028, Rw ) 0.038.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4797
Scheme 11. Plausible Reaction Pathway for the Pt-Catalyzed
Reaction of Alkyne (2) with Diaryl Disulfide (30) (PPh3 on Pt
omitted)
Figure 9. Hammet plot of the rates of insertion of 2t into the S-Pt
bond of 9b-f.
Table 7. Pt-Catalyzed Dimerization-Bisthiolation of 2 with 30
Figure 10. Hammet plot of the rates of insertion of 2t into the
S-Pt bond of 9e and 9h-k.
Scheme 10. Plausible Reaction Pathways for the Insertion of
2t into the S-Pt Bond of 9
29. Given the fact that cis-insertion took place, the formation
of 29 and cis-migration of SAr is more likely.55 The EDG in
ArS would facilitate the formation of 29 due to the nucleophilic
character of complex 9 for the formation of 29 or the
nucleophilic migration of an ArS group onto the coordinated
alkyne moiety in 29.
Pt-Catalyzed Dimerization-Bisthiolaton of Alkyne (2)
by Diaryl Disulfide (ArS)2 (30). The result of the reaction of
trans-8a with 2b (eq 4) suggests that the reaction of 2 with
(ArS)2 (30) giving (Z,Z)-(ArS)(R)CdC(H)-C(H)dC(SAr)(R)
(19) is catalyzed by a PPh3-ligated Pt(0) complex on the basis
of the reaction mechanism shown in Scheme 11: (1) oxidative
addition of 30 to Pt(PPh3)n to afford 8;45 (2) insertion of 2 into
the S-Pt bond of 8 to generate vinyl platinum 16; (3) insertion
of another 2 into the remaining S-Pt bond of 16 to yield
bisvinyl platinum 20; and (4) C-C bond-forming reductive
elimination of 19 with regeneration of Pt(0).38 The results of
the Pt(PPh3)4-catalyzed reaction of some alkynes (2) with diaryl
disulfide (30) are summarized in Table 7. The treatment of
1-octyne (2b, 2.4 mmol) with (PhS)2 (30a, 1.0 mmol) in the
presence of Pt(PPh3)4 (0.05 mmol) under toluene (1 mL) reflux
for 20 h resulted in the production of the anticipated 19b in
86% yield (entry 1). Functional groups such as p-Me (30b),
p-Br (30c), o-Br (30d), and 2,4,5-tri-Cl (30e) on aromatic rings
in 30 barely interfered with the reactions to furnish the
corresponding symmetrical 1:3-dienes (1:2 adducts) in good
yields (entries 2-5). When propargyl alcohol (2n) was em-
(55) It has been proposed that the insertion of CF2dCF2 into the O-Pt
bond of Pt(OMe)(CH3)(dppe) proceeds via a similar five-ligand-coordinated
complex; see:Bryndza, H. Organometallics 1985, 4, 406.

4798 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
Conclusion
The significance of the present paper is summarized as
follows: (1) solid evidence for the insertion of 2 between the
sulfur and the group 10 metal bond of the PR3-ligated complexes
has been provided; (2) the “o-halogen effect” was discovered
under insertion reactions with trans-Pt(SAr)(Cl)(PPh3)2 (7) and
trans-Pt(SAr)2(PPh3)2 (8); (3) the photofacilitated insertion of
alkyne 2 into the S-Pt bond of trans-Pt(SAr)2(PPh3)2 (8) was
revealed; (4) the preference of alkynes for the insertion into
S-Pt bonds, which differs according to the species of phosphine
ligand, was presented; and (5) the insertion of 2 into the S-Pt
bonds of 8 was successfully applied to the Pt-catalyzed
dimerization-bisthiolation of alkyne (2) by disulfide (30). We
do believe these findings make a great contribution toward a
deeper understanding of the mechanisms of M-catalyzed addi-
tion reactions, such as RS-G (1) to alkynes (Scheme 1).
Experimental Section
General Comments. 1H, 13C, and 31P NMR spectra in benzene-
d6, CDCl3, and CD2Cl2 solution were recorded using JEOL JNM-
GSX-270 (270 MHz) and JEOL JNM-Alice 400 (400 MHz)
Figure 11. ORTEP diagram of 19k.
Scheme 12. Pd-Catalyzed vs Pt-Catalyzed Reaction of 2 with
30
1
spectrometers. The chemical shifts in the H and 13C NMR were
recorded relative to Me4Si as an internal standard. The chemical
shifts in the 31P NMR spectra were recorded relative to 85% H3PO4
asanexternalstandard.InordertocalculateNMRyield,SdP(C6H4Me-
p)3 or OdP(C6H4Me)3 was used as an internal standard after relative
intensities with products were measured. IR spectra were recorded
with a Perkin-Elmer model 1600 spectrometer. Combustion analyses
were performed in the Instrumental Analysis Center of the Faculty
of Engineering, Osaka University. GC-mass spectra were recorded
with a Shimazu QP-5000 spectrometer. Preparative TLC was carried
out using Wakogel B-5F silica gel. All reactions were carried out
under a N2 atmosphere. All solvents were distilled before use.
Complex trans-7 was prepared according to the method we have
developed.26 Complex trans-Pt(SAr)2(PPh3)2 (Ar ) C6H4Br-p)
(trans-8) and anti-[Pt(SAr)2(PPh3)]2 (8′) were synthesized by the
oxidative addition of (ArS)2 to Pt(PPh3)4.45 The complex cis-
Pt(SAr)2(PPh3)2 (cis-8) was also prepared according to the litera-
ture.39 Complex Pt(SAr)(Ar′)(dppe) (9) was prepared from the
reaction of trans-Pt(I)(Ph)(PPh3)2 with ArSNa in the presence of
dppe. The m- and p-substituted phenylacetylenes were synthesized
according to the literature.57 Other acetylenes and (ArS)2 (30) were
commercially available. Photoirradiation was performed using a
Toshiba 500 W tungsten lamp. Toshiba UV-33, Y-43, and O-54
were used to filter the light. The X-ray crystal data of trans-Z-10a,
trans-Z-10d, trans-Z-10e, 7j, 27a, and 19k were collected by
Rigaku AFC5R diffraction, ORTEP diagrams of them are shown
with 50% probability ellipsoids, and the crystal and data collection
parameters of them can be accessed either in the Supporting
Information of this article or in the Supporting Information of
literature shown in ref 27.
ployed as an alkyne, the 1:2 adduct (19f; 46%), as well as 1:3
adducts, the formation of which was suggested by mass
spectroscopy, was produced in 14% yield. This result demon-
strates that the multiple insertion of 2 into the S-Pt bond of 8
takes place when 2n was employed as an alkyne. The reactions
with phenylacetylene (2a) and alkynes having OH (2u) and CN
(2v) groups also occurred to afford 19g, 19h, and 19i in
moderate yields (entries 7-9). When eneyne 2w was employed,
conjugated tetraene 19j was obtained in 80% yield as a single
isomer (entry 10). Ethyl phenylpropiolate (2d) also reacted with
30a under xylene reflux (48 h) to afford 38% of the
dimerization-bisthiolation product 19k, the structure of which
was unambiguously determined by X-ray crystallographic
analysis; EtOC(O) groups are located at the 2,3-position of the
1,3-diene moiety (Figure 11).56 The regio- and stereoselectivity
are consistent with those anticipated from the structure of vinyl
platinum 10d, as shown in Figure 2. It should be noted that the
pattern of the reaction of 2 with 30 can be facilely converted
from the simple 1:1 addition producing 32 into a 1:2 addition
and affording 19 by just changing the catalysts from Pd(PPh3)4
to Pt(PPh3)4 (Scheme 12).13 These contrastive reactivities are
attributable to the differing tendencies for C-S bond-forming
reductive elimination of vinyl palladium 31 and vinyl platinum
16; the former underwent C-S bond-forming reductive elimina-
tion, whereas the latter is thermodynamically stable and C-C
bond-formation took place via bisvinyl platinum complex 20.10a
Reaction of Pt(SC6H4Cl-p)(Cl)(PPh3)2 (7a) with Phenylacety-
lene (2a) (eq 1). trans-7a (9.0 mg, 0.01 mmol), SdP(C6H4Me-p)3
(1.7 mg, 0.0051 mmol as an internal standard), and toluene-d8 (0.6
mL) were added to a Pyrex NMR tube under a N2 atmosphere.
After the initial ratio of signals of trans-7a and SdP(C6H4-p-Me)3
was checked by 1H and 31P NMR spectra, 2a (1.0 mg, 0.01 mmol)
was added in the NMR tube under a N2 atmosphere. The reaction
1
at 110 °C was then monitored by H and 31P NMR spectra. The
formation of trans-10a was confirmed in 83% yield after 6 h. The
reactions using other alkynes shown in eq 1 were similarly carried
1
out and monitored by H and 31P NMR spectroscopies.
Reaction of Pt(SC6H4Br-p)(Cl)(PPh3)2 (7b) with an Excess
Amount of p-CF3-Substituted Arylacetylene (2f) (Table 1,
entry 1). trans-7b (9.8 mg, 0.010 mmol), SdP(C6H4-p-Me)3 (1.7
mg, 0.0051 mmol as an internal standard), and C6D6 (0.6 mL) were
(56) Crystal data for Z,Z-19k: space group P21 (#4), a ) 8.1456(4) Å,
b ) 16.984(1) Å, c ) 11.5882(6) Å, ꢀ ) 111.984(2)°, Z ) 2, F ) 1.271
g/cm3, R ) 0.047, Rw ) 0.117.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4799
1
added in a Pyrex NMR tube under a N2 atmosphere. After the ratio
of signals of trans-7a and SdP(C6H4Me-p)3 was checked by H
16a: yellow solid; mp 123 °C; H NMR (400 MHz, C6D6) δ
1
0.83 (t, J ) 7.2 Hz, 3 H), 0.85-0.93 (m, 4 H), 1.00-1.07 (m, 2
H), 1.09-1.17 (m, 2 H), 1.66-1.74 (m, 2 H), 6.39 (d, J ) 8.6 Hz,
2 H), 6.73 (d, J ) 8.4 Hz, 2 H), 6.97-7.05 (m, 20 H), 7.07 (d, J
) 8.6 Hz, 2 H), 7.29 (t, J ) 3.4 Hz, 1 H), 7.80-7.82 (m, 12 H);
31P NMR (160 MHz, C6D6) δ 20.3 (s, JPt-P ) 3065 Hz); IR (KBr)
3054, 2922, 1480, 1463, 1434, 1085, 1006, 808, 742, 692, 522,
512 cm-1. Anal. Calcd for C56H52Br2P2S2Pt: C, 55.77; H, 4.35.
Found: C, 56.00; H, 4.43.
Reaction of trans-8b with 2a (eq 5). trans-8b (10 mg, 0.01
mmol), SdP(C6H4OMe-p)3 (2.3 mg, 0.0060 mmol as an internal
standard), C6D6 (0.6 mL), and phenylacetylene (2a, 10 mg, 0.1
mmol) were added to a Pyrex NMR tube under a N2 atmosphere.
The reaction was then monitored by 1H and 31P NMR spec-
troscopies at 25 °C. The formation of cis-Pt[(Z)-C(H)dC(SAr)-
(Ph)](SAr)(PPh3)2 (Ar ) C6H4Cl-o) (cis-Z-16b) was confirmed in
40% yield after 4 h. After 55 h, complex Z-16b was formed in
95% yield as a mixture of stereoisomers (cis/trans ) 85/15). On
the other hand, the reaction of cis-8b with 2a did not produce 16b
at all after 4 h at 25 °C (eq 6). The authentic 16b was prepared by
the reaction of (Z)-(ArS) (Ph)CdC(SAr)(H) (0.01 mmol) with
Pt(PPh3)2(C2H4) (0.01 mmol) in C6D6 at 25 °C to give 16b (85%
yield with cis/trans ) 95/5 after 22 h).36
and 31P NMR spectroscopies, 2f (17.0 mg, 0.1 mmol) was added
to the NMR tube under a N2 atmosphere. The reaction at 70 °C
was then monitored by 1H and 31P NMR spectroscopies. The
consumption rate of the starting trans-7b obeyed pseudo-first-order
kinetics. The half-life of trans-7b was calculated to be 10.2 h. The
reactions with other arylacetylenes 2 shown in Table 1 were
similarly carried out and monitored by NMR spectroscopy. The
half-lives of trans-7b are summarized in Table 1. Figure 4 shows
the correlation between the values of log(kobs/kobs(H)) and Hammett’s
substituent constants σ and σ+ of X in XC6H4Ct CH.
Reaction of trans-7a with an Excess Amount of 2a (Table 2,
entry 2). trans-7a (9.0 mg, 0.010 mmol), SdP(C6H4Me-p)3 (1.7
mg, 0.0051 mmol as an internal standard), and C6D6 (0.6 mL) were
added to a Pyrex NMR tube under a N2 atmosphere. After the ratio
1
of signals of trans-4a and SdP(C6H4Me-p)3 was checked by H
and 31P NMR spectroscopies, 2a (10.2 mg, 0.1 mmol) was added
to the NMR tube under a N2 atmosphere. The reaction at 70 °C
was then monitored by 1H and 31P NMR spectroscopies. The
consumption rate of the starting trans-7a obeyed pseudo-first-order
kinetics. The half-life of trans-7a was calculated to be 6.1 h.
The reactions using other platinum complexes trans-7 shown in
Table 2 were similarly carried out and monitored by NMR
spectroscopy. The half-lives of trans-7 are summarized in Table
cis-Pt[(Z)-C(H)dC(SAr)(Ph)](SAr)(PPh3)2 (Ar ) C6H4Cl-o)
(cis-16b): 31P NMR (160 MHz, C6D6) δ 19.1 (d, JP-P ) 18 Hz,
JPt-P ) 3327 Hz), 17.5 (d, JP-P ) 18 Hz, JPt-P ) 1855 Hz).
2. Figure 5 shows the correlation between the values of log(kobs
/
kobs(H)) and the Hammett’s substituent constants σ of X in trans-
Pt(SC6H4X-p)(Cl)(PPh3)2.
trans-Pt[(Z)-C(H)dC(SAr)(Ph)](SAr)(PPh3)2 (Ar ) C6H4-
Cl-o) (trans-16b): 31P NMR (160 MHz, C6D6) δ 18.3 (s, JPt-P
)
Ligand-ExchangeReactionbetween7aandtrans-Pt(SC6H4Cl-p)-
(Cl)[P(C6H4Me-p)3]2 (7a′) (eq 2). trans-7a (4.5 mg, 0.005 mmol),
trans-7a′ (4.9 mg, 0.005 mmol), SdP(C6H4Me-p)3 (1.7 mg, 0.0051
mmol as an internal standard), and C6D6 (0.6 mL) were added to
2982 Hz).
Reaction of Pt(SAr)2(PPh3)2 (Ar ) C6H4Br-p, 8a) with
Methyl Propargyl Ether (2n). Photoirradiated Insertion (Table
3). Into a Pyrex NMR tube were added trans-8a (11.0 mg, 0.01
mmol), 2n (7.0 mg, 0.1 mmol), and 0.5 mL of C6D6 under a N2
atmosphere. The tube immersed into a water bath (25 °C) was
irradiated with a 500 W tungsten lamp placed at 5 cm from the
tube, and the reaction was monitored by 1H and 31P NMR
spectroscopies (entry 1). The spectrum taken after 10 min of
photoirradiation showed the formation of 14% cis-Z-16c ac-
companied with the isomerization of trans-8a to cis-8a (cis/trans
) 80/20). After 1 h, Z-16c was formed in 91% yield (cis/trans )
83/17). The cis-Z-16c was isolated by a similar 0.18 mmol scale
reaction carried out in 10 NMR tubes (0.018 mmol scale each)
followed by recrystallization from benzene/hexane to provide 102
mg of pure cis-Z-16c (48% yield).
cis-Z-16c: colorless solid; mp 151 °C; 1H NMR (270 MHz, C6D6)
δ 2.73 (s, 3 H), 3.44 (s, 2 H), 6.82-6.89 (m, 18 H), 7.08 (d, J )
8.4 Hz, 2 H), 7.27 (d, J ) 8.4 Hz, 2 H), 7.46 (dd, JH-P ) 5.4 Hz,
JH-P ) 7.3 Hz, 1 H), 7.53 (d, J ) 8.4 Hz, 22 H), 7.62-7.68 (m,
14 H); 31P NMR (109 MHz, C6D6) δ 19.3 (d, JP-P ) 17.2 Hz,
JPt-P ) 1810 Hz), 21.7 (d, JP-P ) 17.2 Hz, JPt-P ) 3306 Hz); IR
(KBr) 3094, 1559, 1464, 1435, 1180, 1002, 693, 523 cm-1. Anal.
Calcd for C52H44Br2OP2PtS2: C, 53.57; H, 3.80. Found: C, 53.45;
H, 3.75.
1
a Pyrex NMR tube. The reaction was then monitored by H and
31P NMR spectra at 25 °C. The formation of trans-Pt(SC6H4Cl-
p)(Cl)(PPh3)[P(C6H4Me-p)3] (7a′′) was confirmed. The reaction time
and yield of 7a′′ were as follows: 0.5 h, 13%; 1 h, 23%; 24 h,
48%.
7a′′: 31P NMR (160 MHz, C6D6) δ 23.7 (s, JPt-P ) 2692 Hz),
23.3 (s, JPt-P ) 2715 Hz).
The reaction of 7i with 7i′ was similarly carried out and
monitored by NMR spectroscopy. The reaction time and yield of
trans-Pt(SC6H4Cl-o)(Cl)(PPh3)[P(C6H4Cl-p)3] (7i′′) were as follows:
0.5 h, 5%; 1 h, 12%; 24 h, 44%.
7i′′: 31P NMR (160 MHz, C6D6) δ 22.5 (s, JPt-P ) 2710 Hz),
21.9 (s, JPt-P ) 2688 Hz).
Reaction of Pt(SAr)2(PPh3)2 (8a, Ar ) C6H4Br-p) with 2b
(eq 4). Into a Pyrex NMR tube were added 8a (10 mg, 0.01 mmol),
PPh3 (5.2 mg, 0.02 mmol), OdP(C6H4Me-p)3 (3.0 mg, 0.01 mmol
as an internal standard), 2b (26.4 mg, 0.24 mmol), and C6D6 (0.6
mL) under a N2 atmosphere. When the sample was heated at 80
°C for 1 h, the formation of Pt[(Z)-C(H)dC(SAr)(n-C6H13)]-
(SAr)(PPh3)2 (16a) was confirmed by 31P NMR spectroscopy in
29% yield. While the yield of 16a was decreased to 26% after 8 h,
formation of S-bridged complexes 16a′ and 17a was confirmed at
16% (syn/anti ) 31/69) and 5% (40/60) yields, respectively. The
formation of Pt(0) complex 18a and 1,3-diene 19a was also
confirmed at 28% and 35% yields, respectively. The yields of 18a
and 19a reached 78% and 93%, respectively, after 40 h, whereas
the complexes trans-8a, 16a, 16a′, and 17a disappeared.
The reaction of trans-8a (0.01 mmol) with 2n (0.1 mmol) in
darkness was monitored by 31P NMR spectrum, with no insertion
confirmed after 5 days (entry 2). When the photoirradiated reactions
were conducted in the presence of additional PPh3 (0.01 mmol,
0.02 and 0.1 mmol), the formation of 16c was significantly
suppressed (28%, 19%, and 5% of Z-16c, respectively) (entries
3-5). The photoirradiated reaction of trans-8a (0.0025 mmol) with
2n (0.25 mmol) and the reaction of cis-8a (0.0025 mmol) with 2n
(0.25 mmol) were performed for 30 s (entries 6 and 7): The former
provided 2.4% cis-Z-16c (with the remaining cis-8a/trans-8a )
1/99); however, the latter did not produce any detectable amount
of insertion product (cis-8a/trans-8a ) 81/19). The treatment of
anti-[Pt(SAr)2(PPh3)]2 (anti-8a′) (0.005 mmol) with 2n (0.1 mmol)
in the presence of PPh3 (2.6 mg, 0.01 mmol) produced no insertion
Preparation of Authentic 16a.36 Into a two-necked 5 mL
reaction vessel equipped with a stirring bar were added (Z)-(ArS)(n-
C6H13)CdC[C(O)SAr](H) (Ar ) C6H4Br-p) (102 mg, 0.20 mmol),
Pt(PPh3)2(C2H4) (143 mg, 0.20 mmol), and C6H6 (4 mL) under a
N2 atmosphere. After the solution was stirred at 25 °C for 3 h, the
solvent was removed in Vacuo to give trans-Pt[(Z)-C(H)dC(SAr)(n-
C6H13)](SAr)(PPh3)2 (trans-16a) as a yellow solid (182 mg, 0.15
mmol, 75% yield).

4800 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
product even after 2 h of photoirradiation; only the isomerization
of 8a′ was observed (syn-8a′ (δ 19.5)/anti-8a′ (δ 18.9) ) 24/76)
(entry 8). When the reaction of trans-8a with 1 equiv of 2n (0.01
mmol each) was carried out under photoirradiation for 2 h, the
formation of 25% Z-16c (cis/trans ) 83/17) and 19% 8a′ (syn/anti
) 24/76) was confirmed (entry 9). Irradiation of the solutions of
trans-8a (0.01 mmol) and 2n (0.1 mmol) with >330 and >430
nm light using UY33 and Y43 as filters for 1 h resulted in the
formation of 16c in 91% (only Z, cis/trans ) 83/17) and 83% yield
(only cis-Z), respectively (entries 10 and 11). On the other hand,
no insertion took place from irradiation of light at <1770 nm using
O54 as the filter (entry 12). When the reaction of 2n (0.1 mmol)
with trans-8a (0.01 mmol) was performed under the irradiation of
a UV(Hg) lamp (500 W), the complete disappearance of 8a and
the formation of 76% 16c (52% cis-Z, 10% trans-Z, and 14% cis-
E) with a small amount of undetermined products were confirmed
by 31P NMR spectroscopy after 10 min.
Photoinduced Isomerization of cis-Z-16c. The isolated complex
cis-Z-16c (0.01 mmol) and C6D6 (0.5 mL) were placed in a NMR
tube, and the solution was irradiated using a tungsten lamp for 5 h.
The formation of trans-Z-16c (16%) (δ 19.8, s, JPt-P ) 3093 Hz),
cis-E-16c (10%) (δ 19.2, J P-P) 17.2 H, δ 20.9, JP-P ) 17.2 Hz,
JPt-P unreadable), and trans-E-16c (8%) (δ 19.52, s, the value of
JPt-P was unreadable) was confirmed by 31P NMR spectrum.
MHz, C6D6) δ 19.4 (d, JP-P ) 18.3 Hz, JPt-P ) 1865 Hz), 20.9 (d,
JP-P ) 18.3 Hz, JPt-P ) 3286 Hz). cis-Z-16i: 31P NMR (160 MHz,
C6D6) δ 19.5 (d, JP-P ) 17.8 Hz, JPt-P ) 1853 Hz), 20.7 (d, JP-P
) 17.8 Hz, JPt-P ) 3304 Hz). cis-Z-16j: 31P NMR (160 MHz, C6D6)
δ 19.5 (d, JP-P ) 17.8 Hz, JPt-P ) 1849 Hz), 20.75 (d, JP-P
)
17.8 Hz, JPt-P ) 3312 Hz). cis-16k: 31P NMR (160 MHz, C6D6)
Z-isomer: δ 19.5 (d, JP-P ) 17.7 Hz, JPt-P ) 1849 Hz), 20.7 (d,
JP-P ) 17.7 Hz, JPt-P ) 3310 Hz); E-isomer: δ 20.9 (d, JP-P
)
18.4 Hz), 22.4 (d, JP-P ) 18.4 Hz). cis-16l: 31P NMR (160 MHz,
C6D6) Z-isomer: δ 19.5 (d, JP-P ) 17.2 Hz, JPt-P ) 1848 Hz),
21.7 (d, JP-P ) 17.2 Hz, JPt-P ) 3315 Hz); E-isomer: δ 18.8 (d,
JP-P ) 18.4 Hz, JPt-P ) 1741 Hz), 22.2 (d, JP-P ) 18.4 Hz, JPt-P
) 3270 Hz). cis-16m: 31P NMR (160 MHz, C6D6) Z-isomer: δ
19.6 (d, JP-P ) 17.2 Hz, JPt-P ) 1841 Hz), 20.5 (d, JP-P ) 17.2
Hz, JPt-P ) 3337 Hz); E-isomer: δ 18.9 (d, JP-P ) 17.2 Hz), 22.4
(d, JP-P ) 17.2 Hz).
Measurement of Quantum Yield for the Formation of
cis-Z-16c from the Reaction of trans-8a with 2n. The quantum
yield for the formation of cis-Z-16c was determined with 313 nm
light using a 2-hexanone actinometer. Into four NMR tubes were
placed trans-8a (0.01 mmol), 2n (0.1mmol), and C6D6 (0.6 mL),
respectively. Then into four other NMR tubes was placed 2-hex-
anone (58 mM) in C6D6, which was set to match the absorbance
of cis-Z-16c. The samples were irradiated by 313 nm light using
K2CrO4-Na2CO3 aqueous solution as a cutoff filter at 25 °C for
4 h on a merry-go-round apparatus (300 W). The quantum yield of
8a was estimated to be ca. 0.7 by assuming the quantum yield of
the disappearance of 2-hexanone to be 0.327 (Murov, S. L.
Handbook of Photochemistry; Marcel Dekker: New York, 1973; p
207).
Insertion of Other Alkynes into the S-Pt Bond of 8a (eq
7). The reactions of 0.1 mmol of phenylacetylene (2a), 1-octyne
(2b), and 1,1-dimethyl-3-butyne (2o) with 0.01 mmol of trans-8a
were carried out in C6D6 under photoirradiation and were monitored
by 31P NMR spectroscopies in a manner similar to the case of
reactions with 2n. Each reaction provided the corresponding
insertion product Pt[(Z)-C(H)dC(SAr)(R)](SAr)(PPh3)2 (Z-16). The
reaction times and the yields were as follows: 16d (R ) Ph), (cis-
Z, 10 min, 15%), (cis, E/Z ) 17/83, 1 h, 98%); 16a (R ) n-C6H13),
(cis-Z, 10 min, 11%), (Z, cis/trans ) 97/3, 1 h, 87%); 16e (R )
t-Bu), (cis-Z, 1 h, 69%). Z-16d: 31P NMR (109 MHz, C6D6) cis-
isomer: δ 18.4 (d, JP-P ) 17.2 Hz, JPt-P ) 1803 Hz), 21.0 (d, JP-P
) 17.2 Hz, JPt-P ) 3336 Hz); trans-isomer: δ 20.3 (s, JPt-P 3065
Hz). cis-Z-16a: 31P NMR (109 MHz, C6D6) δ 18.3 (d, JP-P ) 18.4
Hz, JPt-P ) 1755 Hz), 22.0 (d, JP-P ) 17.2 Hz, JPt-P ) 3336 Hz).
cis-E-16e: 31P NMR (160 MHz, C6D6) (data collected from a
mixture of stereoisomers) δ 18.8 (d, JPt-P ) 18.3 Hz, JPt-P ) 1756
Hz), 21.8 (d, JP-P ) 18.3 Hz, JPt-P ) 3273 Hz). The spectral data
of 16d and 16e were confirmed by comparison with those of
authentic samples produced by the oxidative addition of corre-
sponding vinylsulfides to Pt(PPh3)2(C2H4).36 The attempted reac-
tions of trans-8a with 4-octyne, diphenylacetylene, and 2-octynoic
acid produced only 8a′ (syn/anti ) 13/87) after 2 h of photoirra-
diation.
Photoinduced Ligand Exchange of 8a with PAr′3 (Ar′ )
C6H4OMe-p; 23) (eq 8). Into both of two NMR tubes were added
trans-8a (0.01 mmol), 23 (2.0 mg, 0.1 mmol), and C6D6 (0.5 mL).
The 31P NMR spectrum taken after 1 h of photoirradiation showed
the formation of 77% Pt(SAr)2(PAr′3)2 (8c) (77/23) and 15%
Pt(SAr)2(PPh3)(PAr′3) (8d) (cis/trans ) 17/83). On the other hand,
no reaction was confirmed by the 31P NMR spectra of the other
sample in darkness for 1 h. The authentic complex 8c was prepared
from the reaction of Pt(Cl)2(PAr′3)2 (0.15 mmol) with p-BrC6H4SH
(0.45 mmol) in CH2Cl2 (10 mL) in the presence of Et3N at 25 °C
for 3 h (58% yield). 8c: a major isomer; 1H NMR (270 MHz, C6D6)
δ 3.17 (s, 18 H), 6.59 (d, J ) 8.8 Hz, 12 H), 6.90 (d, J ) 8.8 Hz,
4 H), 7.10 (d, J ) 8.8 Hz, 4 H), 7.66 (dd, J ) 8.8 Hz, JP-H ) 5.4
Hz, 12 H); 31P NMR (109 MHz, C6D6) δ 21.16 (s, JPt-P ) 2972
Hz). Anal. Calcd for C54H50Br2O6P2PtS2: C, 50.59; H, 4.40. Found:
C, 50.79; H, 4.00. 8c: a minor isomer (data collected from a mixture
of stereoisomers) 1H NMR (270 MHz, C6D6) δ 3.20 (s, 18 H),
6.63 (d, J ) 8.8 Hz, 12 H), 6.89 (d, J ) 8.8 Hz, 4 H), 7.20 (d, J
) 8.8 Hz, 4 H), 7.80 (dd, J ) 8.8 Hz, JH-P ) 5.1 Hz, 12 H); 31P
NMR (109 MHz, C6D6) δ 21.5 (s, JPt-P ) 2745 Hz). 8d: 31P NMR
(109 MHz, C6D6) cis-isomer: δ 20.4 (d, JP-P ) 18.4 Hz), 25.3 (d,
Competitive Insertion between 2a and Substituted Arylacety-
lene (Table 4). The C6D6 solutions of mixtures of 2a (0.1 mmol),
2 (0.1 mmol), and trans-8a (0.01 mmol) were photoirradiated for
1 h, and the ratios of cis-16 (E/Z combined)/cis-16d (E/Z combined)
were calculated by taking 31P NMR spectra: 16g/16d ) 0.17/1;
16f/16d ) 0.28/1; 16h/16d ) 0.72/1; 16i/16d ) 1.1/1; 16j/16d )
1.2/1; 16k/16d ) 1.6/1; 16l/16d ) 4.6/1; 16m/16d ) 4.3/1. The
31P NMR chemical shifts of 16 were confirmed independently by
either the photoirradiated reactions of 2 with trans-8a or the
oxidative addition of the corresponding vinyl sulfide to
Pt(PPh3)2(C2H4).36
JP-P ) 18.4 Hz); trans-isomer: δ 19.3 (d, JP-P ) 505 Hz, JPt-P
2750 Hz), 24.8 (d, JP-P ) 505 Hz, JPt-P ) 2812).
)
Reaction of Pt(SAr)(Ar)(dppe) (Ar ) C6H4OMe-p, 9a) with
DMAD (2t) (eq 9). Into a Pyrex NMR tube were added 9a (8.4
mg, 0.005 mmol), 2t (14.9 mg, 0.10 mmol), and CD2Cl2 (0.6 mL)
under a N2 atmosphere. The reaction at 25 °C was monitored by
31P NMR spectroscopies. The chart taken after 1 h showed the
formation of 27a in 90% yield.
cis-Z-16f: 31P NMR (160 MHz, C6D6) δ 19.3 (d, JP-P ) 17.2
Hz, JPt-P ) 1803 Hz), 21.9 (d, JP-P ) 17.2 Hz, JPt-P ) 3336 Hz).
Preparation of 27a. In a dry two-necked flask equipped with a
magnetic stirring bar were placed 9a (84 mg, 0.1 mmol), CH2Cl2
(6 mL), and DMAD (284 mg, 2.0 mmol). Then the solution was
stirred at 25 °C for 5 h. The resultant mixture was filtered, dried
under vacuum, and purified by recrystallization from CH2Cl2/hexane
to give 27a as a white solid (324 mg, 33%).
cis-16g: 31P NMR (160 MHz, C6D6) Z-isomer: δ 19.3 (d, JP-P
)
18.4 Hz, JPt-P ) 1869 Hz), 20.9 (d, JP-P ) 18.4 Hz, JPt-P ) 3275
Hz); E-isomer: δ 18.6 (d, JP-P ) 18.3 Hz, JPt-P ) 3231 Hz), 21.7
(d, JP-P ) 18.3 Hz, JPt-P ) 3231 Hz). cis-Z-16h: 31P NMR (160
27a: colorless solid; mp 161-163 °C; 1H NMR (270 MHz,
CD2Cl2) δ 2.03 (m, 2 H), 2.43 (m, 2 H), 3.64 (s, 3 H), 3.72 (s, 3
(57) Christine, G.; Andrea, A. Tetrahedron Lett. 2002, 43, 7091.

Insertion of Alkynes into an ArS-Pt Bond
Organometallics, Vol. 27, No. 18, 2008 4801
(s, 2 H), 7.09 (d, J ) 8.1 Hz, 4 H), 7.22 (d, J ) 8.1 Hz, 4 H); 13
H), 6.40 (t, J ) 7.6 Hz, 2 H), 6.65 (dd, J ) 9.6 Hz, J ) 22.0 Hz,
4 H), 6.69-7.87 (m, 22 H); 31P NMR (109 MHz, CD2Cl2) δ 40.2
(d, JP-P ) 2.5 Hz, JPt-P ) 2247 Hz), 41.9 (d, JP-P ) 2.5 Hz, JPt-P
) 1744 Hz); IR (KBr) 3446, 2944, 1709, 1690, 1492, 1435, 1230,
C
NMR (68 MHz, CDCl3) δ 14.06, 21.06, 22.52, 28.56, 28.67, 31.56,
37.47, 129.62, 129.64, 130.79, 131.10, 136.50, 137.89; IR (NaCl)
3019, 2987, 2927, 2855, 1561, 1491, 1462, 1456, 1399, 1378, 1302,
1274, 1210, 1180, 1117, 1104, 1089, 1018, 807, 725 cm-1; mass
spectrum (EI) m/e 466 (M+, 3). Anal. Calcd for C30H42S2: C, 77.19;
H, 9.07; S, 13.74. Found: C, 76.76; H, 9.03; S, 13.39.
1103, 1028, 826, 747, 694, 532 cm-1
. Anal. Calcd for
C46H44O6P2PtS: C, 56.27; H, 4.52. Found: C, 56.20; H, 4.38.
The following data were collected by the reactions of 9 with 2t.
27b: 31P NMR (160 MHz, CD2Cl2) δ 40.2 (d, JP-P ) 2.7 Hz,
JPt-P ) 2358 Hz), 42.6 (d, JP-P ) 2.7 Hz, JPt-P ) 1583 Hz). 27c:
1
19a (entry 3): pale yellow oil; 485 mg, 81%; H NMR (270
MHz, CDCl3) δ 0.84 (t, J ) 6.7 Hz, 6 H), 1.12-1.34 (m, 12 H),
1.38-1.52 (m, 4 H), 2.20 (t, J ) 7.5 Hz, 4 H), 6.98 (s, 2 H), 7.15
(d, J ) 8.5 Hz, 4 H), 7.40 (d, J ) 8.5 Hz, 4 H); 13C NMR (68
MHz, CDCl3) δ 14.05, 22.51, 28.51, 28.60, 31.51, 37.72, 120.28,
131.00, 131.46, 131.95, 134.23, 137.49; IR (NaCl) 2954, 2928,
2855, 1566, 1471, 1387, 1087, 1068, 1009, 813, 728 cm-1; mass
spectrum (EI) m/e 594 (M+, 38). Anal. Calcd for C28H36Br2S2: C,
56.38; H, 6.08. Found: C, 56.51; H, 6.12.
31P NMR (160 MHz, CD2Cl2) δ 40.3 (d, JP-P ) 2.7 Hz, JPt-P
)
2275 Hz), 42.2 (d, JP-P ) 2.7 Hz, JPt-P ) 1660 Hz). 27d: 31P
NMR (160 MHz, CD2Cl2) δ 40.3 (d, JP-P ) 2.7 Hz, JPt-P ) 2230
Hz), 41.9 (d, JP-P ) 2.7 Hz, JPt-P ) 1697 Hz). 27e: 31P NMR
(160 MHz, CD2Cl2) δ 40.4 (d, JP-P ) 2.7 Hz, JPt-P ) 2228 Hz),
41.6 (d, JP-P ) 2.7 Hz, JPt-P ) 1697 Hz). 27f: 31P NMR (160
MHz, CD2Cl2) δ 40.2 (d, JP-P ) 2.7 Hz, JPt-P ) 2224 Hz), 41.9
(d, JP-P ) 2.7 Hz, JPt-P ) 1697 Hz). 27g: 31P NMR (160 MHz,
CD2Cl2) δ 40.6 (d, JP-P ) 2.7 Hz, JPt-P ) 2424 Hz), 43.4 (d, JP-P
) 2.7 Hz, JPt-P ) 1502 Hz).. 27h: 31P NMR (160 MHz, CD2Cl2)
δ 41.1 (d, JP-P ) 2.7 Hz, JPt-P ) 2213 Hz), 42.2 (d, JP-P ) 2.7
Hz, JPt-P ) 1728 Hz). 27i: 31P NMR (160 MHz, CD2Cl2) δ 41.0
(d, JP-P ) 2.7 Hz, JPt-P ) 2206 Hz), 42.4 (d, JP-P ) 2.7 Hz, JPt-P
1
19d (entry 4): pale yellow oil; 440 mg, 74%; H NMR (400
MHz, CDCl3) δ 0.83 (t, J ) 6.8 Hz, 6 H), 1.19-1.26 (m, 12 H),
1.47-1.54 (m, 4 H), 2.23 (t, J ) 7.3 Hz, 4 H), 7.02-7.07 (m, 2
H), 7.08 (s, 2 H), 7.15-7.17 (m, 2 H), 7.20-7.24 (m, 2 H),
7.54-7.56 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 14.04, 22.51,
28.56, 28.67, 31.51, 38.16, 123.81, 127.15, 127.60, 130.13, 132.56,
133.08, 136.60, 137.37; IR (NaCl) 2927, 2855, 1574, 1446, 1427,
1251, 1106, 1020, 889, 747 cm-1; mass spectrum (EI) m/e 594
(M+, 14); HRMS calcd for C28H36Br2S2 594.0625, found 594.0623.
19e (entry 5): colorless solid; 472 mg, 73%; mp 82 °C; 1H NMR
(270 MHz, CDCl3) δ 0.85 (t, J ) 6.7 Hz, 6 H), 1.14-1.35 (m, 12
H), 1.44-1.55 (m, 4 H), 2.25 (t, J ) 7.5 Hz, 4 H), 7.06 (s, 2 H),
7.20 (s, 2 H), 7.45 (s, 2 H); 13C NMR (68 MHz, CDCl3) δ 14.03,
22.50, 28.48, 28.62, 31.48, 38.12, 130.42, 130.51, 130.87, 131.55,
132.25, 133.15, 134.75, 136.83; IR (KBr) 2930, 2836, 1570, 1461,
1433, 1322, 1252, 1112, 1059, 874, 752, 727, 643, 434 cm-1; mass
spectrum (EI) m/e 644 (M+, 24). Anal. Calcd for C28H32Cl6S2: C,
52.11; 5.00. Found: C, 52.56; H, 4.94.
) 1753 Hz); 27j: 31P NMR (160 MHz, CD2Cl2) δ 39.8 (d, JP-P
2.7 Hz, JPt-P ) 2397 Hz), 42.5 (d, JP-P ) 2.7 Hz, JPt-P ) 1542
Hz). 27k: 31P NMR (160 MHz, CD2Cl2) δ 40.0 (d, JP-P ) 2.7 Hz,
JPt-P ) 2387 Hz), 42.6 (d, JP-P ) 2.7 Hz, JPt-P ) 1566 Hz).
)
Reaction of 9f with an Excess Amount of 2t (entry 5, Table
5). 9f (8.1 mg, 0.010 mmol), SdP(C6H4-p-OMe)3 (1.9 mg, 0.0049
mmol as an internal standard), and CD2Cl2 (0.6 mL) were added
to a Pyrex NMR tube under a N2 atmosphere. After the ratio of
signals of 9f and SdP(C6H4-p-OMe)3 was checked by 1H and 31
P
NMR spectra, 2t (10.2 mg, 0.1 mmol) was added to the NMR tube
under a N2 atmosphere. The reaction was then monitored by H
1
and 31P NMR spectroscopies at room temperature. The consumption
rate of the starting 9f obeyed pseudo-first-order kinetics. The half-
life of 9f was calculated to be 0.34 h. The reactions using other
platinum complexes 9, shown in Tables 5 and 6, were similarly
carried out and monitored by NMR spectroscopy. The half-lives
for each reaction are shown in Tables 5 and 6.
19f (entry 6): 46%; colorless solid; mp 135 °C; 1H NMR (270
MHz, CDCl3) δ 3.27 (s, 6 H), 3.93 (s, 4 H), 7.21 (d, J ) 8.6 Hz,
4 H), 7.30 (s, 2 H), 7.42 (d, J ) 8.6 Hz, 4 H); 13C NMR (68 MHz,
CDCl3) δ 58.16, 74.61, 120.93, 130.46, 131.85, 131.97, 132.92,
135.07; IR (KBr) 2922, 2851, 2821, 1470, 1386, 1377, 1261, 1194,
1116, 1085, 1006, 891, 807, 783, 476 cm-1; mass spectrum (EI)
m/e 514 (M+, 14). Anal. Calcd for C20H20Br2O2S2: C, 46.53; H,
3.90. Found: C, 46.77; H, 3.80.
General Procedure of the Pt-Catalyzed Reaction of 2 with
30 (Table 7). Into a 3 mL reaction flask equipped with reflux
condenser and stirring bar were placed 30 (1 mmol), Pt(PPh3)4 (62
mg, 0.05 mmol), toluene (0.5 mL), and 2 (2.4 mmol) under a N2
atmosphere. After the solution was vigorously refluxed for 20 h,
the resultant mixture was separated by PTLC to afford the desired
1:2 adduct 19. When the reaction of (PhS)2 (30) with
MeOCH2Ct CH (2n) was performed in a 5 mL reaction flask
equipped with a Teflon cock at 120 °C for 41 h, 19f was isolated
by recrystallization from Et2O/MeOH (235 mg, 46%). Separation
of the residue by HPLC afforded a mixture of suspected 1:3 adducts
(84 mg, 14% yield), whose formula was tentatively determined by
mass spectroscopy. The reaction of 30a with PhCt CC(O)(OEt)
(2d) was performed using xylene as a solvent at 140 °C for 48 h.
Suspected 1:3 adduct: yellow oil; 1H NMR (270 MHz, CDCl3)
δ 3.30 (s, 6 H), 3.31 (s, 3 H), 3.92 (d, J ) 1.3 Hz, 2 H), 3.93
(s, 2 H), 4.17 (s, 2 H) (the other peaks were unreadable because
the vinyl protons and aromatic protons overlapped with each other);
mass spectrum (EI) m/e 584 (M+, 32); HRMS calcd for
C24H26Br2O3S2 583.9690, found 583.9668.
19g (entry 7): yellow solid; 262 mg, 62%; mp 195-197 °C;
1H NMR (270 MHz, CDCl3) δ 7.01-7.29 (m, 16 H), 7.64 (d, J )
7.8 Hz, 4 H), 7.75 (s, 2 H); 13C NMR (68 MHz, CDCl3) δ 125.82,
127.86, 128.30, 128.68, 128.79, 133.41, 135.58, 138.13, 139.60 (two
signals overlapped); IR (KBr) 3050, 1580, 1478, 1438, 1076, 1025,
895, 892, 765, 737, 700, 689, 600, 473 cm-1; mass spectrum (EI)
m/e 422 (M+, 44). Anal. Calcd for C28H22S2: C, 79.58; H, 5.25; S,
15.17. Found: C, 79.29; H, 5.35; S, 15.04.
1
19b (entry 1): pale yellow oil; 377 mg, 86%; H NMR (270
MHz, CDCl3) δ 0.83 (t, J ) 7.1 Hz, 6 H), 1.10-1.34 (m, 12 H),
1.39-1.52 (m, 4 H), 2.21 (t, J ) 7.3 Hz, 4 H), 7.01 (s, 2 H),
7.16-7.34 (m, 10 H). NOE experiment: Irradiation of a vinyl singlet
at δ 7.01 resulted in a 20% enhancement of the signal of an allyl
proton at δ 2.21; 13C NMR (68 MHz, CDCl3) δ 14.16, 22.53, 28.55,
28.63, 31.53, 37.71, 126.32, 128.86, 130.07, 130.68, 135.00, 137.58;
IR (NaCl) 2956, 2929, 2856, 1583, 1562, 1477, 1465, 1440, 1024,
740, 691 cm-1; mass spectrum (EI) m/e 438 (M+, 27). Anal. Calcd
for C28H38S2: C, 76.65; H, 8.73; S, 14.62. Found: C, 76.25; H, 8.63;
S, 14.45.
19h (entry 8): colorless solid; 255 mg, 62%; mp 84-85 °C; 1H
NMR (270 MHz, CDCl3) δ 1.14 (br, 2 H), 1.36-1.56 (m, 10 H),
2.19 (t, J ) 7.0 Hz, 4 H), 3.31-3.43 (m, 4 H), 6.95 (s, 2 H),
7.14-7.39 (m, 10 H); 13C NMR (68 MHz, CDCl3) δ 25.11, 32.21,
37.65, 62.89, 126.55, 128.97, 130.26, 130.26, 130.77, 134.75,
137.42; IR (KBr) 3285, 2934, 2862, 1582, 1576, 1555, 1476, 1438,
1066, 1056, 1024, 749, 739, 692 cm-1; mass spectrum (EI) m/e
414 (M+, 29). Anal. Calcd for C24H30O2S2: C, 69.52; H, 7.29; S,
15.46. Found: C, 69.21; H, 7.17; S, 15.03.
1
19c (entry 2): pale yellow oil; 370 mg, 82%; H NMR (270
MHz, CDCl3) δ 0.83 (t, J ) 6.8 Hz, 6 H), 1.11-1.34 (m, 12 H),
1.38-1.53 (m, 4 H), 2.18 (t, J ) 7.6 Hz, 4 H), 2.33 (s, 6 H), 6.96
19i (entry 9): colorless solid; 260 mg, 64%; mp 88-90 °C; 1H
NMR (270 MHz, CDCl3) δ 1.84 (quint, J ) 7.2 Hz, 4 H), 2.23 (t,

4802 Organometallics, Vol. 27, No. 18, 2008
Kuniyasu et al.
J ) 7.2 Hz, 4 H), 2.38 (t, J ) 7.2 Hz, 4 H), 7.03 (s, 2 H), 7.18-7.35
(m, 10 H); 13C NMR (68 MHz, CDCl3) δ 16.12, 24.22, 36.07,
119.27, 127.17, 129.21, 130.65, 131.12, 133.53, 136.40; IR (KBr)
2241, 1587, 1562, 1477, 1460, 1440, 1423, 1294, 1070, 1024, 900,
892, 840, 737, 699, 688, 603, 466, 436, 418 cm-1; mass spectrum
(EI) m/e 404 (M+, 16). Anal. Calcd for C24H24N2S2: C, 71.25; H,
5.98; N, 6.92. Found: C, 70.72; H, 5.98; N, 6.85.
0.49 mmol), NiCl2(PPh3)2 (9.9 mg, 0.015 mmol), and THF (6 mL)
under a N2 atmosphere. PhMgBr (1.0 mL of a 0.8 M solution in
THF, 0.8 mmol) was added from the addition funnel at 0 °C over
a period of 5 min. After the mixture was refluxed for 19 h, 6 mL
of HCl (1 N) was added. The reaction mixture was extracted with
Et2O/H2O and dried over MgSO4. The sample was subjected to
PTLC to give 10% (n-C6H13)(PhS)CdCH-CHdC(Ph)(n-C6H13)
with vinyl protons (J ) 12.2 Hz), indicating that two vinyl protons
of 19b were located at the vicinal positions.
19j (entry 10): yellow solid; 345 mg, 80%; mp 120-121 °C;
1H NMR (270 MHz, CDCl3) δ 1.41-1.65 (m, 8 H), 2.00-2.13
(m, 4 H), 2.16-2.27 (m, 4 H), 6.43-6.50 (m, 2 H), 7.05-7.30
(m, 10 H), 7.47 (s, 2 H); 13C NMR (68 MHz, CDCl3) δ 22.04,
22.79, 26.23, 27.01, 125.06, 127.37, 128.67, 130.74, 131.23, 135.81,
137.56, 137.69; IR (KBr) 2944, 2922, 2855, 2819, 1613, 1580,
Acknowledgment. Partial support of this work was
through the Grant-in-Aid for Scientific Research, Ministry
of Education and Science. Thanks are due to the Instrumental
Analysis Center, Faculty of Engineering, Osaka University,
for assistance in obtaining mass spectra with a JEOL JMS-
DX303 instrument. One of the authors, F.Y., expresses his
special thanks to The Global Center of Excellence Program
“Global Education and Research Center for Bio-Environ-
mental Chemistry” of Osaka University.
1477, 1438, 1261, 1108, 1100, 1024, 842, 798, 736, 687 cm-1
;
mass spectrum (EI) m/e 430 (M+, 32); HRMS calcd for C28H30S2
430.1789, found 430.1782.
19k (entry 11): yellow solid; 106 mg, 38%; mp 156-157 °C;
1H NMR (400 MHz, CDCl3) δ 0.90 (t, J ) 7.3 Hz, 6 H), 3.94 (q,
J ) 7.1 Hz, 4 H), 7.02-7.14 (m, 12 H), 7.23-7.26 (m, 8 H); 13
C
NMR (100 MHz, CDCl3) δ 13.63, 60.54, 127.34, 127.70, 127.80,
127.98, 128.39, 129.21, 131.75, 133.94, 137.52, 154.54, 165.99;
IR (KBr) 3057, 2986, 1710, 1581, 1482, 1440, 1363, 1259, 1208,
1040, 746, 698, 532 cm-1. Anal. Calcd for C34H30O4S2: C, 72.06;
H, 5.34. Found: C, 71.79; H, 5.27. The structure of 19k was
unambiguously determined by X-ray crystallographic analysis.
Confirmation of Regiochemistry of 19 (Ni-catalyzed reac-
tion of 19b with PhMgBr). Into a 10 mL flask equipped with an
addition funnel and a reflux condenser were placed 19b (213 mg,
Supporting Information Available: X-ray crystal data for 19k
and 27a (CIF) and UV-vis spectra of trans-8a and cis-Z-16c.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM800464Y