A prototype of transition-metal-catalyzed carbothiolation of alkynes

Full text of DOI:10.1021/ja010261o

5108
J. Am. Chem. Soc. 2001, 123, 5108-5109
Scheme 1. General Trend of RE and OA of the S-C Bond
from/to Pd and Pt Complexes
A Prototype of Transition-Metal-Catalyzed
Carbothiolation of Alkynes
Kunihiko Sugoh, Hitoshi Kuniyasu,* Taeko Sugae,
Atsushi Ohtaka, Yasutomo Takai, Aoi Tanaka,
Chikako Machino, Nobuaki Kambe,* and Hideo Kurosawa*
Scheme 2. Schematic Strategy for Carbothiolation of Alkyne
Department of Applied Chemistry, Faculty of Engineering
Osaka UniVersity, Suita, Osaka 565-0871, Japan
ReceiVed January 30, 2001
conversion into C-Pt-C by the insertion (IS) of alkyne into the
S-Pt bond,5f,j and (3) subsequent C-C bond-forming RE10
(Scheme 2).
The organic sulfides, which once had been considered to be
catalyst poison,1 have been proved to be versatile reagents for a
variety of transition-metal-catalyzed reactions.2-5 These trans-
formations offered unique methodologies to build up desired
organic compounds and clearly revealed the high reactivities of
thiolate ligands on transition metals. The Pd-catalyzed decarbo-
nylation of thioester R1SC(O)R2 (1) (R1 ) aryl or alkyl; R2 )
aryl or vinyl)3 and cross-coupling reactions of R1SM (2) (M:
typical metal) with R2X (3) (X: halogen or OTf),4 both furnishing
R1SR2 (4), are among the typical examples. It was also reported
that the Pd-catalyzed addition of diaryl disulfide (ArS)2 (5) to
terminal alkyne R3CCH (6) gave vinyl sulfide (Z)-R3(ArS)Cd
CH(SAr) (7).5k These reactions indicated that facile S-C bond-
forming reductive elimination (RE) from Pd(II) occurred to
complete the catalytic cycles.6 In marked contrast, we have
recently found that the stoichiometric S-C bond-cleaving oxida-
tive addition (OA) of vinyl sulfide 7 (R3 ) aryl, SiMe3, CH2-
OMe) to Pt0Ln afforded cis-Pt[(Z)-CHdC(SAr)(R3)](SAr)Ln (8),7
sugesting that the S-C bond-forming RE could be suppressed
by simply switching metals from Pd to Pt in the above catalyses
(Scheme 1).8,9 Disclosed herein is a novel method for regio- and
stereoselective additions of carbon and sulfur functionalities to
alkynes based on the following working hypothesis: (1) S-Pt-C
unit formation patterned after the Pd-catalyzed reactions, (2)
It became evident that the reaction of PhSC(O)Ph (1a) (1.0
mmol) with 1-octyne (6a) (1.2 mmol) carried out in the presence
of Pt(PPh3)4 (0.05 mmol) under toluene (0.5 mL) reflux for 10 h
indeed produced the anticipated (Z)-2-(phenylthio)-1-phenyl-1-
octene (9a) in 77% yield (eq 1, run 1 of Table 1).11 Neither
isomers of 9a nor PhSPh (4a) was detected.12 When the reaction
of 1a with 6a was performed with Pd(PPh3)4 as a catalyst,3 4a
was formed in 40% yield; however, no formation of 9a was
confirmed (run 2).13 The functional groups such as p-Me (1b),
p-Br (1c), and p-NO2 (1d) on aromatic rings of R1 did not
adversely interfere with the reactions (runs 3-5). The reactions
of BuSC(O)Ph (1e) or PhCH2SC(O)Ph (1f) with 6a were very
sluggish to give 33% and 46% of adducts (9e or 9f) under xylenes
reflux for 46 h, respectively (runs 6-9). The platinum-catalyzed
arylthiolation of alkynes was not so sensitive to the electronic
effect on the aromatic rings in R2; i.e., 74% of 9g (p-Me) and
79% of 9h (p-CN) were isolated (runs 10 and 11). The group R2
can be replaced by a vinyl group to afford the vinylthiolation
product 9i in 63% yield with the stereochemistry of vinyl moiety
retained (run 12). On the other hand, PhSC(O)Me (1j) was inert
(run 13), while the reaction with PhSC(O)C8H17-n (1k) produced
hydrothiolation product,5c,j 2-phenylthio-1-octene in 73% yield
(run 14). Terminal alkynes such as 6-hydroxy-1-hexyne (6b),
5-cyano-1-pentyne (6c), phenyl acetylene (6d), and (trimethyl-
silyl)acetylene (6e) all underwent the carbothiolation by 1c to
furnish the corresponding adducts (9l-9o) in moderate yields
(runs 15-18). The carbothiolation proceeded at both of the C-C
triple bonds smoothly when 1,7-octadiyne (6f) was employed (run
19).
(1) (a) Hegedus, L. L.; McCabe, R. W. Catalyst Poisoning; Marcel
Deckker: New York, 1984. (b) Hutton, A. T. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon
Press: Oxford, U.K., 1984; Vol. 5, p 1151.
(2) For reviews, see: (a) Ogawa, A. J. Organomet. Chem. 2000, 611, 463.
(b) Kondo, T.; Mitsudo, T. Chem. ReV. 2000, 100, 3205. (c) Han, L.; Tanaka,
M. J. Chem. Soc., Chem. Commun. 1999, 395.
(3) Osakada, K.; Yamamoto, T.; Yamamoto, A. Tetrahedron Lett. 1987,
28, 6321.
(4) (a) Zheng, N.; McWilliams, J. C.; Fleitz, F. J.; Armstrong, J. D., III;
Volante, R. P. J. Org. Chem. 1998, 63, 9606. (b) Ishiyama, T.; Mori, M.;
Suzuki, A.; Miyaura, N. J. Organomet. Chem. 1996, 525, 225. (c) Mart´ınez,
A. G.; Barcina, J. O.; Cerezo, A. F.; Subramanian, L. R. Synlett 1994, 561.
(d) Dickens, M. J.; Gilday, J. P.; Mowlem, T. J.; Widdowson, D. A.
Tetrahedron 1991, 47, 8621. (e) Carpita, A.; Rossi, R.; Scamuzzi, B.
Tetrahedron Lett. 1989, 30, 2699. (f) Kosugi, M.; Ogata, T.; Terada, M.; Sano,
H.; Migita, T. Bull. Chem. Soc. Jpn. 1985, 58, 3657. (g) Migita, T.; Shimizu,
T.; Asami, Y.; Shiobara, J.; Kato, Y.; Kosugi, M. Bull. Chem. Soc. Jpn. 1980,
53, 1385. (h) Murahashi, S.-I.; Yamamura, M.; Yanagisawa, K.; Mita, N.;
Kondo, K. J. Org. Chem. 1979, 44, 2408. (i) Kosugi, M.; Shimizu, T.; Migita,
T. Chem. Lett. 1978, 13.
Then to get the convincing information on the mechanism of
Pt-catalyzed carbothiolation of alkynes by thioester, some sto-
ichiometric reactions were monitored by 31P NMR spectra as
follows. The OA of 1c (0.02 mmol) to Pt(PPh3)4 (0.01 mmol) in
C6D6 (0.6 mL) proceeded at 25 °C to give a mixture of trans-
Pt(SR1)[C(O)Ph](PPh3)2 (R1 ) C6H4Br-p) (trans-10c) (76%) and
anti-(PPh3)[PhC(O)]Pt(µ-SR1)2Pt[C(O)Ph](PPh3) (anti-10c′) (7%)
after 1 h (eq 2).14 The decarbonylation required more stringent
conditions; a solution of isolated trans-10c (0.01 mmol) in
(5) (a) Hua, R.; Takeda, H.; Onozawa, S.; Abe, Y.; Tanaka, M. J. Am.
Chem. Soc. 2001, 123, 2899. (b) Arisawa, M.; Yamaguchi, M. Org. Lett. 2001,
3, 763. (c) Ogawa, A.; Ikeda, T.; Kimura, K.; Hirao, T. J. Am. Chem. Soc.
1999, 121, 5108. (d) Han, L.; Tanaka, M. Chem. Lett. 1999, 863. (e) Ogawa,
A.; Kuniyasu, H.; Takeba, M.; Ikeda, T.; Sonoda, N.; Hirao, T. J. Organomet.
Chem. 1998, 564, 1. (f) Han, L.; Tanaka, M. J. Am. Chem. Soc. 1998, 120,
8249. (g) Ogawa, A.; Kawakami, J.; Mihara, M.; Ikeda, T.; Sonoda, N.; Hirao,
T. J. Am. Chem. Soc. 1997, 119, 12380. (h) Ogawa, A.; Takeba, M.;
Kawakami, J.; Ryu, I.; Kambe, N.; Sonoda, N. J. Am. Chem. Soc. 1995, 117,
7564. (i) Ishiyama, T.; Nishijima, K.; Miyaura, N.; Suzuki, A. J. Am. Chem.
Soc. 1993, 115, 7219. (j) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Kambe,
N.; Sonoda, N. J. Am. Chem. Soc. 1992, 114, 5902. (k) Kuniyasu, H.; Ogawa,
A.; Miyazaki, S.; Ryu, I.; Kambe, N.; Sonoda, N. J. Am. Chem. Soc. 1991,
113, 9796.
(8) The result of palladium- and platinum-catalyzed reaction of 5 with
isocyanide also supported this propensity. Kuniyasu, H.; Sugoh, K.; Moon,
S.; Kurosawa, H. J. Am. Chem. Soc. 1997, 119, 4669.
(9) Low, J. J.; Goddard, W. A., III. J. Am. Chem. Soc. 1984, 106, 6928.
(10) (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.
(11) The regiochemistry of 9 was confirmed by the reduction of the ArS
group and the stereochemistry was determined by N.O.E. experiment between
vinyl and C-3 methylene protons. Trost, B. M.; Ornstein, P. L. Tetrahedron
Lett. 1981, 22, 3463.
(12) The decarbonylation of 1a (in the absence of 6a) was not catalyzed at
all by Pt(PPh3)4 at 110 °C after 15 h.
(13) Other effective catalysts for the formation of 9a among those examined
were RhCl(PPh3)3 (21%), [RhCl(CO)2]2 (29%), and IrCl(PPh3)2 (CO) (11%).
(14) The authentic trans-10c, anti-10c′, trans-11c, and 11c′ were indepen-
dently prepared and fully characterized by NMR spectra and elementary
analyses. The structure of anti-10c′ was unambiguously determined by X-ray
analysis. See the Supporting Information for more details.
(6) The details of S-C bond-forming RE from Pd(II) have been investi-
gated. Mann, G.; Baranano, D.; Hartwig, J. F.; Rheingold, A. L.; Guzei, I. A.
J. Am. Chem. Soc. 1998, 120, 9205.
(7) Kuniyasu, H.; Ohtaka, A.; Nakazono, T.; Kinomoto, M.; Kurosawa,
H. J. Am. Chem. Soc. 2000, 122, 2375.
10.1021/ja010261o CCC: $20.00 © 2001 American Chemical Society
Published on Web 05/02/2001

Communications to the Editor
J. Am. Chem. Soc., Vol. 123, No. 21, 2001 5109
Table 1. The Pt-Catalyzed Carbothiolation of 6 with 1a
Scheme 3. Proposed Fates of S-M-C units in the Presence of
Alkyne
and Pt(PPh3)4 (0.05 mmol) under toluene (0.5 mL) reflux for 17
h also generated the desired 9a in 83% yield (eq 5).18 Moreover,
unlike the case of Pd-catalyzed reaction forming 7,5k the reaction
of (PhS)2 (5a) (1.0 mmol) with 6a (2.4 mmol) performed in the
presence of Pt(PPh3)4 (0.05 mmol) under toluene (0.5 mL) reflux
for 20 h furnished Z,Z-R3(PhS)CdCHCHdCR3(SPh) (R3
C6H13-n) (13a) in 86% yield (eq 6).
)
The different outcomes between Pd- and Pt-catalyzed reactions
described above can be explained as follows (Scheme 3). Both
of the Pd- and Pt-catalyzed reactions would generate similar M(II)
complexes with S-M-C fragments such as R1S-M-R2 (M )
Pd, 14; M ) Pt, 11) and M[(Z)-CHdC(SAr)(R3)](SAr) (M )
Pd, 15; M ) Pt, 8). When M is Pd, after the formation of 14 and
15, 4 and 7 would be smoothly eliminated without incorporating
6 under toluene reflux condition.6 In stark contrast, when M is
a Unless otherwise noted, 1.0 mmol of 1, 1.2 mmol of 6, 0.05 mmol
of Pt(PPh3)4 under toluene (0.5 mL) reflux for 10-15 h. b Pd(PPh3)4
(0.05 mmol). c PhSPh (4a) 40%. d Xylenes reflux, 46 h. e 2-phenylthio-
1-octene (73%). f 2.4 mmol of 6e, 42 h in a sealed tube. g 1.2 mmol of
1c, 0.5 mmol of 6f.
2
Pt, due to the thermodynamical disadvantage of S-sp C bond-
toluene-d8 (0.6 mL) at 110 °C afforded decarbonylated complexes
trans-Pt(SAr)(Ph)(PPh3)2 (trans-11c) (16%) and (Ph)(PPh3)Pt(µ-
SR1)2Pt(Ph)(PPh3) (11c′) (syn/anti ) 50/50) (81% based on Pt)
after 1 h (eq 3). The reaction of isolated trans-11c (0.01 mmol)
with 6a (0.14 mmol) in toluene-d8 (0.5 mL) at 110 °C formed
Pt(PPh3)2(R3CCH) (R3 ) C6H13-n) (12a) in 62% yield after 6 h
(eq 4). It should be noted that p-BrC6H4SPh (4c) was not detected
at all from the reaction mixture, while 9c (65%) was obtained,
meaning a catalytic cycle of the carbothiolation could be
composed of a series of reactions of eqs 2-4.15-17
forming RE of 4 and 7, 11 and 8 would have enough lifetime to
undergo the regio- and stereoselective IS of 6 into the S-Pt bonds
to give vinyl platinum 16 and divinyl platinum 17, leading to the
2
2
formation of 9 and 13 by the more facile sp C-sp C bond-forming
RE from Pt(II).10,19
In conclusion, this study provided a simple concept to achieve
the transition-metal-catalyzed carbothiolation of alkynes by
exploiting contrastive reactivities of thiolate ligands on palladium
and platinum complexes. Our continuous efforts will be focused
on the extension of the present model to other addition systems.
Acknowledgment. Partial support of this work through CREST of
the Japan Science and Technology Cooperation and Grants-in-Aid for
Scientific Research, Ministry of Education, Culture, Sports, Science and
Technology of Japan, is gratefully acknowledged. 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.
Supporting Information Available: Experimental procedures, spec-
tral data of the products, and X-ray data (PDF). This material is available
free of charge via the Internet at http://pubs.acs.org.
JA010261O
(16) The reaction of 11c′ (0.005 mmol) with 6a (0.14 mmol) in the presence
of PPh3 (0.01 mmol) provided 32% of 12a and 60% of 9c after 6 h. Because
trans-11c was regenerated by the reaction of 11c′ with PPh3 in toluene at 110
°C, there may be an equilibrium between 11c and 11c′.
(17) Because some unidentified signals together with those of anti-10c′,
trans-11c, 11c′, and 12a were detected in the 31P NMR spectra of the reaction
of trans-10c with 6a (14 equiv) at 110 °C, the possibility of the IS of 6 into
the complex 10 cannot be precluded at the moment. On the other hand, no
reaction took place on a similar treatment of anti-10c′ with 6a in the absence
of PPh3 at 110 °C.
Finally, the generality of the present strategy shown in Scheme
2 was further tested. The reaction of PhSNa (2a) (1.1 mmol) with
PhI (3a) (1.0 mmol)4g,i conducted in the presence of 6a (1.3 mmol)
(18) The reaction with Pd(PPh3)4 instead of Pt(PPh3)4 produced 4a in 79%
yield; however, no formation of 9a was confirmed.
(19) The failure of carbothiolation in the reactions of runs 13 and 14 in
3
2
(15) No intermediate was detected even if the reaction of trans-11c with
6a was conducted at 70 °C (70% of 12a and 72% of 9c after 62 h).
Table 1 may be attributable to sp C-sp C bond-forming RE in the process from
16 to 9.