Catalytic synthesis of thiobutyrolactones via CO insertion into the C-S bond of thietanes in the presence of a heterodinuclear organoplatinum-cobalt complex

Article abstract of DOI:10.1039/b305799b

Heterodinuclear organoplatinum-cobalt complex having a 1,2-bis(diphenylphosphino)ethane ligand (dppe)MePt-Co(CO)₄ catalyzes CO insertion into the C-S bond of thietanes in THF at 100°C under 1.0 MPa of CO for 2 h to give γ-thiobutyrolactone in q

Full text of DOI:10.1039/b305799b

Catalytic synthesis of thiobutyrolactones via CO insertion into the C–S
bond of thietanes in the presence of a heterodinuclear
organoplatinum–cobalt complex
Masaki Furuya, Susumu Tsutsuminai, Hiroto Nagasawa, Nobuyuki Komine, Masafumi Hirano and
Sanshiro Komiya*
Department of Applied Chemistry, Faculty of Technology, Tokyo University of Agriculture and Technology,
2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan. E-mail: komiya@cc.tuat.ac.jp; Fax: +81-42-387-7500;
Tel: +81-42-388-7043
Received (in Cambridge, UK) 23rd May 2003, Accepted 26th June 2003
First published as an Advance Article on the web 9th July 2003
Heterodinuclear organoplatinum-cobalt complex having a
1,2-bis(diphenylphosphino)ethane ligand (dppe)MePt–
Co(CO)4 catalyzes CO insertion into the C–S bond of
thietanes in THF at 100 °C under 1.0 MPa of CO for 2 h to
give g-thiobutyrolactone in quantitative yield.
role in this catalytic carbonylation. In contrast, the analogous
heterodinuclear Pt–Mn, –Fe, and –Mo complexes (dppe)MePt–
MLn[MLn = Mn(CO)5 (2),2c,h FeCp(CO)2 (3),2c MoCp(CO)3
(4)2c] and the Pd–Co complex (dppe)MePd–Co(CO)4 (5)2f,j
showed no or low catalytic activity for the carbonylation of
thietane (runs 3–6). Although the catalytic carbonylation of
thietane is known to be catalyzed by Co2(CO)8 or a mixed metal
system Co2(CO)8/Ru3(CO)12, their catalytic activities are less
than in our case.4 When the ancillary methyl ligand in the
heterodinuclear Pt–Co complex was displaced by other organic
ligands, a slight change in catalytic activity for this carbonyla-
tion was observed. The catalytic activities for neopentyl- and
The cooperative effect of transition metals both in homo- and
heterogeneous catalyses is one of the most intriguing unsolved
subjects.1 We previously prepared a series of heterodinuclear
organometallic complexes having both M–MA and M–C bonds,
LnRM–MALAnLBm (M = Pt, Pd; MA = Mo, W, Co, Fe, Mn, Re;
L = cod, dppe, bpy; LA,LB = Cp, CO)2 and found significantly
accelerated stoichiometric CO insertion reactions into the Pd–C
or Pt–C bonds in the Pd–Co or Pt–Co complex (dppe)MeM–
Co(CO)4, giving (dppe)(MeCO)M–Co(CO)4 (M = Pd, Pt),2f,j
in which facile alkyl group transfer and CO insertion at Co
followed by oxidative addition to the acyl–cobalt bond are
involved. We now report the highly efficient catalytic carbony-
lation of thietanes promoted by organoplatinum–cobalt hetero-
dinuclear complexes giving thiobutyrolactones. The synthesis
of such thiolactones by simple carbonylative ring expansion
may also provide a useful tool in organic synthesis.3
phenylplatinum(II) derivatives [(dppe)RPt–Co(CO)4: R
=
CH2CMe3 (6), Ph (7)]† decreased to give slightly lower yields
than 1 under the same conditions, whereas the acetylplatinum–
cobalt complex (dppe)(MeCO)Pt–Co(CO)4 (8)† showed com-
parable catalytic activity to 1 (runs 7–9). When 2-methyl-
thietane4 was used as a reactant, g-thiovalerolactone5 was
exclusively formed in 89% yield (run 10). The result indicates
that insertion of carbon monoxide took place at the less hindered
C–S bond of 2-methylthietane, suggesting involvement of an
SN2 type C–S bond cleavage reaction. In fact, carbonylation of
2,5-dimethylthietane4 failed under the same reaction condi-
tions.
In order to obtain further mechanistic insights into the present
catalytic carbonylation reaction, the stoichiometric reaction of 1
was carried out. When organoplatinum–cobalt complex 1 was
treated with thietane in acetone-d6 at room temperature for 1 h,
heterolytic cleavage of the Pt–Co bond took place to give a
cationic (thietane-kS)platinum(II) complex with [Co(CO)4]2
anion, [PtMe(thietane-kS)(dppe)]+[Co(CO)4]2 (9) [eqn. (2)].‡
When thietane was heated to 100 °C under 1.0 MPa of CO in
THF for 2 h in the presence of 2 mol% of (dppe)MePt–Co(CO)4
(1),2c g-thiobutyrolactone was selectively formed in quantita-
tive yield (eqn. (1), Table 1, run 1). This carbonylation of
thietanes could be achieved quantitatively even at ambient
temperature, if the reaction was performed for a day (run 2).
(1)
(2)
Since the corresponding mononuclear platinum(II) com-
plexes such as PtMeCl(dppe) and [PtMe(MeCN)(dp-
pe)]+[BF4]2
and
the
anionic
cobalt
complex
[PPN]+[Co(CO)4]2 showed no catalytic activity, the presence
Further treatment of 9 with 0.1 MPa of CO at room
temperature afforded a mixture of 1 (71%) and acetylplatinum
of the Pt–Co bond is considered to play an important synergistic
Table 1 Catalytic carbonylation of thietane by heterodinuclear organoplatinum–cobalt complexes
Temper-
Run
Catalyst (mol%)
ature/ °C
Time/h
Yield(%)
1
2
3
4
5
6
7
8
9
H
H
H
H
H
H
H
H
H
Me
(dppe)MePt–Co(CO)4 (1) (2.0)
1 (5.0)
100
30
2
24
5
5
5
2
2
2
2
99
96
0
0
8
16
60
84
96
89
(dppe)MePt–Mn(CO)5 (2) (5.0)
(dppe)MePt–FeCp(CO)2 (3) (5.0)
(dppe)MePt–MoCp(CO)3 (4) (5.0)
(dppe)MePd–Co(CO)4 (5) (2.0)
(dppe)(Me3CCH2)Pt–Co(CO)4 (6) (2.0)
(dppe)PhPt–Co(CO)4 (7) (2.0)
(dppe)(MeCO)Pt–Co(CO)4 (8) (2.0)
1 (2.0)
100
100
100
100
100
100
100
100
10
2
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CHEM. COMMUN., 2003, 2046–2047
This journal is © The Royal Society of Chemistry 2003

complex 8 (25%) with concomitant formation of g-thiobutyr-
olactone in 91% yield in 2 days.
materials” in Tokyo University of Agriculture and Technol-
ogy.
A plausible mechanism of this catalytic reaction is proposed
as shown in Scheme 1.
Notes and references
† Heterodinuclear Pt–Co complexes, (dppe)RPt–Co(CO)4 [R = CH2CMe3
(6); Ph (7)] were prepared in good yields by simple metathesis reactions of
PtR(NO3)(dppe) [R = CH2C(Me)3, Ph] with sodium tetracarbonylcobaltate
Na[Co(CO)4].2c 6: Yield 87%, mp 155–157 °C (dec.). Anal. Calcd. for
C35H35CoO4P2Pt: C, 50.31; H, 4.22. Found: C, 49.98; H, 4.28%. IR (KBr,
cm21): 2020, 1934, 1900, 1847 (nCO). 1H NMR (acetone-d6, rt, 300.4
MHz): d 0.65 (s, CH2CMe3), 2.10 (br, 2JPtH = 64 Hz, CH2Me3), 2.3–2.7 (m,
dppe CH2), 7.5–7.9 (m, dppe Ph). 31P{1H} NMR (acetone-d6, rt, 121.6
MHz): d 42.0 (s, 1JPtP = 3999 Hz, P trans to Co), 47.8 (s, 1JPtP = 1521 Hz,
P trans to CH2CMe3). 7: Yield 85%, mp 193–198 °C (dec.). Anal. Calcd. for
C36H29CoO4P2Pt: C, 51.38; H, 3.47. Found: C, 51.74; H, 3.67%. IR (KBr,
cm21): 2027, 1954, 1927, 1886 (nCO). 1H NMR (acetone-d6, rt, 300.4
MHz): d 2.3–2.7 (m, dppe CH2), 6.53 (t, 3JHH = 7.2 Hz, p-H of Ph), 6.66
(dt, 5JPH = 1.6 Hz, 3JHH = 7.2 Hz, m-H of Ph), 7.02 (t, 4JPH
=
3JHH = 7.2
3
Hz, JPtH = 37 Hz, o-H of Ph), 7.4–7.9 (m, dppe Ph). 31P{1H} NMR
2
1
(acetone-d6, rt, 121.6 MHz): d 42.0 (d, JPP = 2 Hz, JPtP = 3809 Hz, P
2
1
trans to Co), 47.8 (d, JPP = 2 Hz, JPtP = 1661 Hz, P trans to Ph).
(dppe)(MeCO)Pt–Co(CO)4 (8)2f,j was synthesized by the oxidative addition
of Co(COMe)(CO)4 to Pt(styrene)(dppe).
‡ Spectroscopic data for 9: 1H NMR (acetone-d6, rt, 300.4 MHz): d 0.46
(dd, 3JPH = 3.9, 6.0 Hz, 2JPtH = 56.8 Hz, Pt–Me), 2.4–2.7 (m, dppe CH2),
3.0–3.4 (br, SCH2CH2), 3.5–3.8 (br, SCH2), 7.4–7.9 (m, dppe Ph). 31P{1H}
NMR (acetone-d6, rt, 121.6 MHz): d 42.9 (d, 2JPP = 2 Hz, 1JPtP = 3510 Hz,
P trans to S), 47.8 (d, 2JPP = 2 Hz, 1JPtP = 1820 Hz, P trans to Ph).
Scheme 1
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The first step of the catalytic cycle is coordination of thietane
to Pt to induce heterolytic cleavage of the Pt–Co bond, giving
[PtMe(thietane-kS)(dppe)]+[Co(CO)4]2. Then the [Co(CO)4]2
anion attacks the less-substituted a-S carbon of the coordinated
thietane to cause C–S bond cleavage giving the dinuclear
complex (dppe)MePt–SCHR(CH2)2–Co(CO)4. The formation
of such ring-opened products has been shown for the analogous
reactions of heterodinuclear complexes (dppe)RPt–M(CO)5 (M
= Mn, Re) with three-membered heterocycles such as thiir-
anes.2h A facile insertion of CO into the cobalt–carbon bond
followed by C–S bond formation results in the formation of g-
thiobutyrolactone and regeneration of the starting Pt–Co
heterodinuclear complex to close the catalytic cycle.
In conclusion, organoplatinum–cobalt heterodinuclear com-
plexes are shown to catalyze the efficient carbonylation of
thietanes under mild conditions. This high catalytic activity is
considered to be caused by the presence of a platinum–cobalt
bond. Elucidation of the origin of this cooperative effect is
under investigation.
The work was financially supported by Grant-in-Aid for
Scientific Research from the Ministry of Education, Science,
Culture, Sports and Technology, Japan and the 21st Century
COE (Center of Excellence) program of “Future Nano-
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