The key to oxidative addition of acyclic vinyl sulfide to M(0) complex [3]

Full text of DOI:10.1021/ja993796e

J. Am. Chem. Soc. 2000, 122, 2375-2376
Scheme 1. Oxidative Addition of Vinyl Sulfide 1 to M
2375
The Key to Oxidative Addition of Acyclic Vinyl
Sulfide to M(0) Complex
Hitoshi Kuniyasu,* Atsushi Ohtaka, Takeo Nakazono,
Masanori Kinomoto, and Hideo Kurosawa*
Table 1. OA of 1 to 2 in C6D6 (C6H6)
Department of Applied Chemistry, Faculty of Engineering
run
1
conditiona
time
12 h
20 min
24 h
12 h
20 min
48 h
24 h
3, yield %
Osaka UniVersity, Suita, Osaka 565-0871, Japan
1
2
1a
1a
a
b
C6H6
C6D6
3a, 78b
3a, 12c,d
3a, 92c
3b, 86b
3b, 9c,e
3f, 54b
ReceiVed October 25, 1999
3
4
5
6
1b
1b
1f
a
b
a
b
C6H6
C6D6
C6D6
C6D6
The C-S bond activation by transition-metal complexes has
received increasing attention for efficient catalytic and stoichio-
metric transformations using organic sulfides. For example, great
effort has been devoted to the cleavage of the thiophen C-S bond
to get insight about hydrodesulfurization that is of great impor-
tance in petrochemistry.1 The oxidative addition (OA) of the C-S
bond has also been reported on aryl-S,2 allyl-S,3 aroyl-S,4
imidoyl-S,5 and strained alkyl-S6 bonds. However, the funda-
mental insight on the OA of acyclic vinyl sulfide 1 to low-valent
metal (M) (Scheme 1), the simplest sp2-C-S bond cleavage, is
much more sparse, though the process has been postulated to be
involved in a number of nickel-catalyzed cross coupling reactions
using 1 and organometallic reagents.7 To our knowledge, since
an early example of OA of 1 with Fe2(CO)10 affording a dinuclear
complex in 1961,8 no practical progress has been made to shed
light on such a fundamental subject in organometallic chemistry.9
We wish to report here the first example of OA of 1 to Pt(0)
(M ) Pt), in which substituents at A and B in 1 are proved to
play a pivotal role in realizing the reaction. A variety of vinyl
1gf
3g, 13c,g
a Conditions: (a) preparative scale (0.17-1.0 mmol); (b) 0.02-0.03
mmol scale in an NMR tube. b Isolated yield. c NMR yield. d No
intermediate was confirmed. e 13% of Pt[(E)-(p-tolS)(Ph)CdC(H)(Stol-
p)](PPh3)2 (5b) was formed. f 10 equiv of 1g to 2 was used. g 15% of
Pt[(Z)-(p-tolS)(CH3OCH2)CdC(H)(Stol-p)](PPh3)2 (5g) was formed.
(1) For recent examples: (a) Αre´valo, A.; Berne´s, S.; Garcia, J. J.; Maitlis,
P. M. Organometallics 1999, 18, 1680. (b) Jones, W. D.; Chin, R. M.; Hoaglin,
C. L. Organometallics 1999, 18, 1786. (c) Palmer, M. S.; Rowe, S.; Harris,
S. Organometallics 1998, 17, 3798. (d) Garcia, J. J.; Mann, B. E.; Adams,
H.; Bailey, N. A.; Maitlis, P. M. J. Am. Chem. Soc. 1995, 117, 2179. (e)
Dong, L.; Duckett, S. B.; Ohman, K. F.; Jones, W. D. J. Am. Chem. Soc.
1992, 114, 151. (f) Bianchini, C.; Meli, A. Synlett 1997, 643. (g) Zhang, X.;
Dullaghan, C. A.; Watson, E. J.; Carpenter, G. B.; Sweigart, D. A.
Organometallics 1998, 17, 2067. (h) Bianchini, C.; Meli, A. Acc. Chem. Res.
1998, 31, 109.
(2) (a) Osakada, K.; Maeda, M.; Nakamura, Y.; Yamamoto, T.; Yamamoto,
A. J. Chem. Soc., Chem. Commun. 1986, 442. (b) Han, L.; Choi, N.; Tanaka,
M. J. Am. Chem. Soc. 1997, 119, 1795. (c) Adams, R. D.; Katahira, D. A.;
Yang, L. Organometallics 1982, 1, 235.
Figure 1. ORTEP diagram of 4 (Ph on DPPE omitted).
sulfides 1 shown in Scheme 2 were prepared and the feasibility
of OA to Pt(PPh3)2(C2H4) (2) was investigated (eq 1 and Table
1). After many attempts, we have ultimately found that the
(3) (a) Yamamoto, T.; Akimoto, M.; Saito, O.; Yamamoto, A. Organo-
metallics 1986, 5, 1559. (b) Osakada, K.; Chiba, T.; Nakamura, Y.; Yamamoto,
T.; Yamamoto, A. Organometallics 1989, 8, 2602. (c) Osakada, K.; Matsu-
moto, K.; Yamamoto, T.; Yamamoto, A. Organometallics 1985, 4, 857. (d)
Osakada, K.; Ozawa, Y.; Yamamoto, A. J. Organomet. Chem. 1990, 399,
341. (e) Miyauch, Y.; Watanabe, S.; Kuniyasu, H.; Kurosawa, H. Organo-
metallics 1995, 14, 5450. (f) Planas, J. G.; Hirano, M.; Komiya, S. Chem.
Lett. 1998, 123.
(4) (a) Shaver, A.; Uhm. H. L.; Singleton, E.; Liles, D. C. Inorg. Chem.
1989, 28, 847. (b) Osakada, K.; Yamamoto, T.; Yamamoto, A. Tetrahedron
Lett. 1987, 28, 6321. (c) Crudden, C. M.; Alper, H. J. Org. Chem. 1995, 60,
5579.
(5) Kuniyasu, H.; Sugoh, K.; Moon, S.; Kurosawa, H. J. Am. Chem. Soc.
1997, 119, 4669.
reaction of (Z)-1,2-bis(p-tolylthio)styrene (1a) with 2 under very
mild conditions (25 °C) in benzene indeed provided the desired
OA product cis-Pt[(Z)-C(H)dC(Stol-p)(Ph)](Stol-p)(PPh3)2 (3a)
in 78% isolated yield as a single product by simple filtration of
the crude reaction mixture (eq 1). The 31P NMR spectrum of 3a
showed a couple of doublets centered at δ 18.9 (JP-P ) 17 Hz,
JPt-P ) 1847 Hz) and δ 20.1 (JP-P ) 17 Hz, JPt-P ) 3240 Hz),
meaning two PPh3s positioned cis. No intermediates or byproducts
were observed, when a small-scale reaction was monitored by
1H and 31P NMR spectra (run 2). Because the complex 3a
isomerized to trans-isomer in C6D6 at 50 °C in the presence of
PPh3 (cis/trans ) 20/80 after 22 h), the cis-3a was definitely the
kinetic product of the OA of 1a to 2. Although efforts to obtain
a high-quality crystal of 3a were unsuccessful, a single X-ray
crystallographic analysis of Pt[(Z)-C(H)dC(Stol-p)(C6H4Cl-p)]-
(Stol-p)(DPPE) (4; DPPE; bis(diphenylphosphino)ethane) pro-
duced by the OA of 1c to 2 followed by the clean PPh3-for-DPPE
substitution demonstrated that OA took place at the terminal vinyl-
C-S bond with the stereochemistry of the vinyl moiety retained
(Figure 1).10
(6) (a) Matsunaga, P. T.; Hillhouse, G. L. Angew. Chem., Int. Ed. Engl.
1994, 33, 1748. (b) Adams, R. D.; Pompeo, M. P. Organometallics 1990, 9,
1718. (c) Adams, R. D.; Pompeo, M. P. Organametallics 1992, 11, 2281. (d)
Adams, R. D.; Perrin, J. L. J. Am. Chem. Soc. 1999, 121, 3984.
(7) (a) Okamura, H.; Miura, M.; Takei, H. Tetrahedron Lett. 1979, 43. (b)
Cristau, H. J.; Chabaud, B.; Labaudiniere, R.; Christol, H. J. Org. Chem. 1986,
51, 875. (c) Cristau, H. J.; Chabaud, B.; Labaudiniere, R.; Christol, H.
Organometallics 1985, 4, 657. (d) Pridgen, L. N.; Killmer, L. B. J. Org. Chem.
1981, 46, 5402. (e) Wenkert, E.; Ferreira, T. W. J. Chem. Soc., Chem.
Commun. 1982, 840. (f) Fiandanese, V.; Marchese, G.; Mascolo, G.; Naso,
F.; Ronzini, L. Tetrahedron Lett. 1988, 29, 3705.
(8) King, R. B.; Treichel, P. M.; Stone, F. G. A. J. Am. Chem. Soc. 1961,
83, 3600.
(9) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles
and Application of Organotransition-Metal Chemistry; University Science
Books: Mill Valley, CA, 1987; pp 279-353.
(10) Crystal data of 4: space group P1h(No. 2) with a ) 21.111(9) Å, b )
25.113(9) Å, c ) 11.598(8) Å, R ) 90.01(5)°, â ) 105.96(5)°, γ ) 108.46-
(3)°, Z ) 4, F ) 1.162 g/cm3, R ) 0.059, and Rw ) 0.067.
The OA of the E-isomer 1b to 2 provided 86% of cis-Pt[(E)-
C(H)dC(Stol-p)(Ph)](Stol-p)(PPh3)2 (3b) by a similar preparative
10.1021/ja993796e CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/26/2000

2376 J. Am. Chem. Soc., Vol. 122, No. 10, 2000
Communications to the Editor
Scheme 2
Scheme 3. A Proposed Route of OA of 1 to 2
Scheme 4. A Proposed Route of RE of the C-S Bond18
procedure (run 3). Contrary to the reaction using 1a, the formation
of olefin-coordinated complex11 Pt[(E)-(p-tolS)(Ph)CdC(H)(Stol-
1
p)](PPh3)2 (5b) was confirmed by H and 31P NMR spectra at
the early stage of the reaction (run 4). To understand the electronic
effect of substrates on the present OA of 1 to 2 in more detail,
competitive reactions were performed by using vinyl sulfides (1a
and 1c-e) possessing different substituents in p-XC6H4 at A (eq
2). The results clearly indicated that the electron-withdrawing
group facilitated the OA; 1c (X ) Cl) reacted about 2.0 times
faster than 1a (X ) H), and 1a about 2.2 times faster than 1d (X
) Me) and 14 times faster than 1e (X ) NH2).
vinyl sulfides 1h (A ) B ) C ) H), 1i (A ) C ) H, B ) Ph),
1j (A ) Ph, B ) H, C ) Stol-p), 1k (A ) Stol-p, B ) C ) H),
1l (A ) n-C6H13, B ) Stol-p, C ) H), 1m (A ) t-Bu, B ) Stol-
p, C ) H), and 1n (A ) C ) Ph, B ) H) did not give any desired
OA products and ended in no reaction (1l, 1m, and 1n) or
formation of olefin-coordinated complex (1h, 1i, 1j, and 1k) even
under more forcing conditions (50 °C).12
On the basis of the above observations, we propose the reaction
mechanism of the OA of 1 to 2 as follows. The olefin-coordinated
complex 5 generated by the ligand exchange of ethylene for 1
would be an intermediate, where all four substituents are bent
down (Scheme 3).13 Then Pt(0) would move toward sterically
less hindered terminal vinyl carbon to form a zwitterionic species
6 possessing anionic charge at â-carbon. The complex 6 can be
stabilized to a great extent by both Ar14 (or Me3Si15 or MeOCH2)
and ArS16 groups at A and B through delocalization of the negative
charge, and presumably that is why the electron-withdrawing
group in Ar at A accelerates the reaction. Finally, after a minimum
rotation about the C-C bond to direct the anion lobe coplanar
with the C-S antibonding orbital to afford 7,17 the SAr- group
would be pushed out and migrate onto the Pt atom, resulting in
the formation of 3. During the process, the two PPh3s on Pt remain
cis coordinated and the stereochemistry of substituents on vinyl
is retained. Recently, Hartwig and co-workers have reported the
mechanism of C-S bond-forming reductive elimination (RE)
from Pd(II), in which they found that the electron-withdrawing
group in C6H4X in 8 promoted RE and proposed intriguing
transition state 9 (Scheme 4).18 Considering the microscopic
reversibility between RE and OA, similar electronic effects to
stabilize the transition state of OA of the C-S bond to M(0) could
be equally rationalized.19
The OA of vinyl sulfide 1f having Me3Si or 1g (10 equiv)
having MeOCH2 in place of Ar at A also took place to furnish
the corresponding vinyl platinum complexes 3f and 3g in 54%
(48 h) and 13% (24 h) yield, respectively (runs 5 and 6). Both
Ar (or R3Si or MeOCH2) and ArS groups at A and B (not C) in
1 were indispensable to achieve the OA; attempted reactions using
(11) Chaloner, P. A.; Davies, S. E.; Hitchcock, P. B. J. Organomet. Chem.
1997, 527, 145 and references therein.
(12) To ascertain whether the failure of OA in these substrates is attributed
to a kinetic or thermodynamic factor, vinyl thiolate platinum trans-Pt(CHd
CH2)(SPh)(PPh3)2 (9) was synthesized and the possibility of its reductive
elimination to form 1h was examined. However, a solution of 9 with 2 equiv
of PPh3 at 70 °C provided [Pt(CHdCH2)(SPh)(PPh3)2]2 (48%) with 10% of
1,3-butadiene after 21 h, and no formation of 1h was observed. Some examples
of stable vinyl platinum thiolate complexes have been known. Stang, P. J.;
Zhong, Z.; Kowalski, M. H. Organometallics 1990, 9, 833.
(13) (a) Bland, W. J.; Burgess, J.; Kemmitt, R. D. W. J. Organomet. Chem.
1968, 15, 217. (b) Bland, W.; Kemmitt, R. D. J. Chem. Soc. A 1968, 1278.
(14) Bordwell, F. G.; Bares, J. E.; Bartmess, J. E.; McCollum, G. J.; Puy,
M. V. D.; Vanier, N. R.; Matthews, W. S. J. Org. Chem. 1977, 42, 321.
(15) Originating from pπ-σ* conjugation (negative hyperconjugation)
t
which is absent in the Bu group. (a) Ojima, I. In The Chemistry of Organic
In summary, we substantiated here the first experimental
evidence of OA of vinyl sulfide to a platinum complex, in which
the modulation of the electronic factor of substituents as well as
their position on vinyl was the secret to attain the reaction. The
generality of the present methodology for the cleavage of other
vinylic compounds is currently under investigation.
Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley-Interscience:
Chichester, 1989. (b) Wiberg, K. B.; Castejon, H. J. Am. Chem. Soc. 1994,
116, 10489.
(16) (a) Negishi, E. Organometallics in Organic Synthesis; Wiley: New
York, 1980; Vol. 1. (b) Bordwell, F. G.; Puy, M. V. D.; Vanier, N. R. J. Org.
Chem. 1976, 41, 1885. (c) Gro¨bel, B. T.; Seebach, D. Synthesis 1977, 357.
(17) Rappoport, Z. Acc. Chem. Res. 1981, 14, 7.
(18) Mann, G.; Baran˜ano, D.; Hartwig, J. F.; Rheingold, A. L.; Guzei, I.
A. J. Am. Chem. Soc. 1998, 120, 9205.
(19) Similar stabilization effects have also been reported with C-O and
C-N bond forming RE. (a) Hartwig, J. F.; Richards, S.; Baranano, D.; Paul,
F. J. Am. Chem. Soc. 1996, 118, 3626. (b) Mann, G.; Hartwig, J. F. J. Am.
Chem. Soc. 1996, 118, 13109. (c) Widenhoefer, R. A.; Buchwald, S. L. J.
Am. Chem. Soc. 1998, 120, 6504. (d) Driver, M. S.; Hartwig, J. F.
Organometallics 1997, 16, 5706.
Supporting Information Available: Experimental details, X-ray data,
and tables of atomic coordiates and Biso/Beq,anisotropic displacement
parameters, bond lengths, and bond angles (PDF). This material is
available free of charge via the Internet at http://pubs.acs.org.
JA993796E