The Pt-Catalyzed Carboselenation of Alkynes by Selenoesters

Article abstract of DOI:10.1021/ol0354223

(Matrix presented) The Pt-catalyzed carboselenation of terminal alkynes with selenoesters provided vinylselenides regio- and stereoselectively in moderate yields.

Full text of DOI:10.1021/ol0354223

ORGANIC
LETTERS
2003
Vol. 5, No. 21
3871-3873
The Pt-Catalyzed Carboselenation of
Alkynes by Selenoesters
Takayoshi Hirai, Hitoshi Kuniyasu,* Tomohiro Kato, Yumi Kurata, and
Nobuaki Kambe*
Department of Molecular Chemistry & Frontier Research Center, Graduate School of
Engineering, Osaka UniVersity, Suita, Osaka 565-0871, Japan
kuni@chem.eng.osaka-u.ac.jp; kambe@chem.eng.osaka-u.ac.jp
Received July 29, 2003
ABSTRACT
The Pt-catalyzed carboselenation of terminal alkynes with selenoesters provided vinylselenides regio- and stereoselectively in moderate yields.
Although the transition-metal-catalyzed additions of het-
eroatom-containing compounds to C-C unsaturated com-
pounds represented by hydrosilylation have been studied for
more than three decades,1 the utilities of organochalcogenides
with Y-X bonds (Y ) SR1, SeR1; X ) element or functional
group) have been recognized only lately.2 We have recently
demonstrated that basic knowledge of the ligand behavior
of thiolates on Pd and Pt complexes3 could be exploited to
develop new reactions, that is, the Pt-catalyzed carbothiola-
tion of alkynes RCCH (1).4 The concept we have elucidated
is quite simple: (1) formation of an intermediate with the
S-Pt-C fragment patterned after Pd-catalyzed S-C bond-
forming cross-coupling reaction;5 (2) insertion of 1 into the
S-Pt bond to furnish a complex with a vinyl-C-Pt-C
fragment; and (3) vinyl-C-C bond-forming reductive
elimination with regeneration of Pt(0) (Scheme 1, Y ) SR1).
Herein we wish to report on the Pt-catalyzed carboselenation
of 1, an extension of the protocol to selenium analogues (Y
) SeR1).6
Scheme 1. Schematic Strategy for Carbothiolation and
Carboselenation of 1
First, the reaction of 1-octyne (1a) (1.2 mmol) with PhSeC-
(O)Ph (2a) (1.0 mmol) was carried out in the presence 0.05
mmol of Pt(PPh3)4 in toluene (0.5 mL) under vigorous reflux
conditions for 20 h. The crude reaction mixture was then
subjected to preparative TLC. The anticipated Z-(n-C6H13)-
(PhSe)CdCH(Ph) (3a),7 the product of decarbonylatiVe
arylselenation, was isolated in 89% yield (entry 1 of Table
1). Neither the regio- and stereoisomers of 3a nor PhSePh
(1) (a) Ojima, I.; Li, Z.; Zhu, J. In The Chemistry of Organic Sillicon
Compounds; Rappoport, Z., Apeloig, Y., Eds.; Wiley-Intercience: Chish-
ester, UK, 1989; Chapter 29. (b) Collman, J. P.; Hegedus, L. S.; Norton, J.
R.; Finke, R. G. Principles and Applications of Organotransition Metal
Chemistry; University Science Books: Mill Valley, CA, 1987; p 523.
(2) Kuniyasu, H. In Catalytic Heterofunctionalization; Togni, A., Gru¨tz-
macher, H. Eds.; Wiley: Zu¨rich, Switzerland, 2001; p 217.
(3) (a) Kuniyasu, H.; Sugoh, K.; Moon, S.; Kurosawa, H. J. Am. Chem.
Soc. 1997, 119, 4669. (b) Kuniyasu, H.; Ohtaka, A.; Nakazono, T.;
Kinomoto, M.; Kurosawa, H. J. Am. Chem. Soc. 2000, 122, 2375.
(4) (a) Kuniyasu, H.; Kurosawa, H. Chem. Eur. J. 2002, 8, 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.
(5) Kondo, T.; Mitsudo, T. Chem. ReV. 2000, 100, 3205.
(6) The Pd-catalyzed Se-C bond-forming reductive elimination has been
reported. (a) Kuniyasu, H.; Ogawa, A.; Miyazaki, S.; Ryu, I.; Kambe, N.;
Sonoda, N. J. Am. Chem. Soc. 1991, 113, 9796. (b) Beletskaya, I. P.; Sigeev,
A. S.; Peregudov, A. S.; Petrovskii, P. V. J. Organomet. Chem. 2000, 605,
96. (c) Nishiyama, Y.; Tokunaga, K.; Sonoda, N. Org. Lett. 1999, 1, 1725.
(7) The stereo- and regiochemistry of 3a were determined by NOE and
the value of JC-Se, respectively. Cullen, E. R.; Guziec, F. S.; Murphy, C.
J.; Wong, T. C.; Andersen, K. K. J. Chem. Soc., Perkin Trans. 2 1982,
473.
10.1021/ol0354223 CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/16/2003

Table 1. The Pt-Catalyzed Carboselenation of 1a with 2a
Table 2. The Pt-Catalyzed Carboselenation of 1 with 2aa
isolated yield
of 3 (%)
isolated yield
entry
1
R
entry
2
R1
R2
of 3 (%)
1
2
3
4
5
6
1b
1c
1d
1e
1f
PhCH2
3k ; 72
1
2b
3
4
5
6
7
8f
9
2a Ph
2a Ph
2b 4-CF3C6H4
2c 4-MeC6H4
2d Ph
Ph
Ph
Ph
Ph
3a ; 89
3a ; 0c
3b; 80
3c; 81
3d ; 68d
3e; 83
3f; 65e
3g; 81g
3h ; 35
3i; 24
3j; 0
HO(CH2)3
HO(1-cyclohexyl)
NC(CH2)3
Ph
3l; 56b
3m ;86
3n ; 68
3o; 61c,d
3p ; 31e,f
C6H4CF3-4
C6H3Cl2-2,4
C6H4OMe-4
1g
4-MeOC6H4
2e Ph
a 1.2 mmol of 1, 1.0 mmol of 2, and 0.05 mmol of Pt(PPh3)4 under
toluene (0.5 mL) reflux for 20-30 h. b E/Z ) 5/95. c 3o E/Z ) 10/90. d 5c
(19%). e 3p E/Z ) 12/88. f 5d (31%).
2f
Ph
2g 4-MeOC6H4 C6H4OMe-4
2h Ph trans-C(H)dC(H)Ph
10h
11h
2i
2j
Ph
4-MeC6H4
C(H)dCMe2
t-Bu
cm2 of CO afforded 5e in 42% yield with a trace amount of
3q (<1%) (Scheme 2).
a Unless otherwise noted, 1.2 mmol of 1a, 1.0 mmol of 2, and 0.05 mmol
of Pt(PPh3)4 under toluene (0.5 mL) reflux for 20-40 h. b Pd(PPh3)4 (0.05
mmol). c PhSePh (4a) 72%. d 2-(Phenylseleno)-1-octene (18%). e Z-(n-
C6H13)(R1Se)CdC(H)C(O)(R2) (5a) (11%). f 40 h. g 5b (9%). h 7 days.
Scheme 2
(4a) was obtained. In stark contrast, when the reaction was
performed with Pd(PPh3)4 instead of Pt(PPh3)4, 3a was hardly
obtained (<1%) and the major product was 4a (72%),
indicating that Se-C bond-forming reductive elimination was
facile from the Pd(II) complex after decarbonylation even
in the presence of 1a (entry 2).6 The results of the reactions
of 1a with various R1SeC(O)R2 (2) are summarized in Table
1. All reactions performed with electron-withdrawing or
-donating groups in aromatic rings in R1 and R2 provided
the desired arylselenation products as major products (entries
3-8). When PhSeC(O)C6H4CF3-4 (2d) was employed,
2-(phenylseleno)-1-octene was also produced in 18% yield
(entry 5). It must be noted that, in the case of R2 ) C6H4-
OMe-4, Z-(n-C6H13)(R1Se)CdC(H)C(O)(R2) (R1 ) Ph, 5a;
R1 ) C6H4OMe-p, 5b), the products of aroylselenation,8 were
also produced in 11% and 9% yields, respectively. The
Vinylselenation took place with use of 2h and 2i to give the
corresponding dienes albeit in low yields (entries 9 and 10).
On the other hand, the selenoester with t-Bu as R2 was totally
ineffective (entry 11).
A possible mechanism for the present carboselenation of
1 by 2 is shown in Scheme 3 (PPh3 omitted). The oxidative
Scheme 3. A Possible Reaction Pathway for the Pt-Catalyzed
Carboselenation of 1 (PPh3 Omitted)
The results of reactions of some alkynes (1) with 2a are
summarized in Table 2. The functionalities such as PhCH2-,
HO-, and NC- were tolerant toward the arylselenation of
2a (entries 1-4). The reaction employing phenylacetylene
(1f) formed 5c in 19% yield together with 61% (E/Z ) 10/
90) of 3o (entry 5) and the yield of 5 was increased by
introducing 4-MeO in the phenyl group to furnish 5d in 31%
yield (entry 6). Then, to anticipate the increment of the
formation of 5, some reactions of 1g with 2f were next
examined. As a result, the reaction performed under 10 kg/
addition of the Se-C bond of 2 to Pt(0) would trigger the
reaction to give Pt(SeR1)[C(O)R2] (6). The following de-
carbonylation produced R1Se-Pt-R2 (7) and then stereo-
and regioselective insertion of 1 into the Se-Pt bond would
furnish vinyl platinum 8,9 making the C-C bond-forming
reductive elimination from Pt(II) possible to afford 3 with
(8) The aroylselenation of alkyne by selenoester through the Cu-catalyzed
Sonogashira-type coupling and subsequent addition of in situ generated
selenol to R,â-alkynone are known. Zhao, C. Q.; Huang, X.; Meng, J. B.
Tetrahedron Lett. 1998, 39, 1933.
3872
Org. Lett., Vol. 5, No. 21, 2003

regeneration of Pt(0).10 If 1 inserted into the Se-Pt bond of
6 prior to the decarbonylation and then reductive elimination
occurred from the resultant vinyl platinum 9, 5 would be
obtained.
In conclusion, this study substantiated that the strategy for
arylthiolation of 1 shown in Scheme 1 (Y ) SR1) also can
be successfully applied to arylselenation (Y ) SeR1),
providing a new entry for the facile preparation of function-
alized vinylselenides.11 Furthermore, the possibility of aroyl-
selenation was also implicated.
Acknowledgment. The authors gratefully acknowledge
the support for this work by a Grant-in-aid for Scientific
Research, Ministry of Education, Culture, Sports, Science
and Technology of Japan. 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.
(9) The insertion of 1 into the Se-Pt bond also can be involved in Pt-
catalyzed hydroselenation of 1. Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu,
I.; Sonoda, N. Tetrahedron Lett. 1992, 33, 5525.
(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) As to the synthetic utility of vinylselenides, see: (a) Comasseto, J.
V.; Ling, L. W.; Petragnani, N.; Stefani, H. A. Synthesis 1997, 373. (b)
Paulmier, C. Selenium Reagents and Intermediates in Organic Synthesis;
Pergamon Press: Oxford, UK, 1986. (c) Yamazaki, S. ReV. Heteroatom
Chem. 1999, 21, 43.
Supporting Information Available: Synthetic details.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OL0354223
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