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Coupling of Epoxides to PtII-Complexes with Carbon Dioxide and the Structure of a Cyclic Metallacarbonate.

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L. A. Paquette, H. Kiinzer, K. E. Green, 0. De Lucchi, G. Licini, L.
Pasquato, G. Valle, J. Am. Chem. SOC.108 (1986) 3453; L. A. Paquette,
T. M. Kravetz, P. Chdrumilind, Teiruhedron 42 (1986) 1789; T.M.
Kravetz, L. A. Paquette, J. Am. Chem. SOC.107 (1985) 6400; L. A. Paquette, U. s. Racherla, J. Urg. Chem. 52 (1987)3250; L. A. Paquette, M.
Kugelchuk, M. L. McLaughlin, ibrd. 52 (1987)4732.
IUPAC name: Dinaphtho[Z,l -e: 1’,2’-g][l,4]dithiocinS,S,S.S-tetraoxide.
Control experiments confirm the higher reactivity of 1 compared to the
bis(phenylsu1fonyl)ethylenes. The reason may be attributed to the relief of
strain at the dienophilic carbons upon change of hybridization from spz to
sp3. 1.4-Benzodithiin S,S,S,S-tetraoxide, which is structurally related to I ,
has also been reported to be more reactive: E. Wenkert. C. A. Broka, Finn.
Chem. Lett. 1984,126;J. Nakayama, Y Nakamura, M. Hoshino, Hetero-
G. Heimchen, R. Karge, I. Weetrnan in R. Scheffold (Ed.): Modern Sjniheiic Methods, Vol. 4, Springer, Berlin 1986, p. 261 ; L. A. Paquette in
J. D. Morrison (Ed.): Asymmetric Synthesis, Vol. 3 , Academic Press, New
York 1984, p. 455; W Oppolzer, Angen. Chem. 96 (1984) 840; Angew.
Chem. Inf. Ed. EngI. 23 (1984) 876; Tetrahedron 43 (1987) 1969; H.
Wiirziger, Kontukte 1984 (Darmstadtj ( 2 j , 3.
D. J. Cram, R. C. Helgeson, K. Koga, E. P. Kyba, K. Madan, L. R. Sousa,
M. G. Siege], P. Moreau, G. W. Gokel, J. M. Timko, G. D. Y. Sogah, J.
Org. Chem. 43 (1978)2758.
W. L. F. Armarego, E. E. Turner, L Chem. Soc. 1957, 13.
[lo] F.Di Furia, G. Licini, G. Modena, 0. De Lucchi, Tetrahedron Lett. 30
(1989)2575.
[ l l ] S. Danishefsky, T. Kitahara, C.-F. Yan, J. Morris, 1 Am. Chem. SOC.1Of
(1979) 6996.
[12] All reactions for checking the diastereoselectivity were carried out directly
in the NMR tube in deuterochloroform mixtures and for the preparative
runs in dichloromethane. All reactions were complete within 24-48 h at
room temperature, except for isoprene whose reaction was run in refluxing
chloroform. Isolated yields are in all cases > 90%. All the new compounds
have been fully characterized. The simplicity of the reaction is remarkable
as in many instances simple mixing of the reagents at room temperature
leads to precipitation of a single crystalline adduct.
1131 An X-ray structure determination confirms the stereochemical assignment. The diffrdctometric analysis was performed by Dr. G . VuNe (Centro
Studi Biopolimeri del C.N.R.. via Marzolo 1,1-35131Padova, Italy).
co2
Scheme 1.
simple epoxides to the co_mplexes [PtMe,(N%)] (1 a:
NX = 2,2’-bipyridine; 1 b: NN = 1,lO-phenanthroline), in
which the unstable complexes B are trapped by reaction with
carbon dioxide to give the stable metallacarbonate complexes C . Similar metallacarbonates have recently been reported
to be formed upon reaction of carbon dioxide with
[Ir(CH,CMe,O)(q-C,Me,)(PMe,)j and with [RhCIH(CH,COMe)(PMe,),] .[‘‘I
Reaction of 1 a or 1 b, which are highly reactive towards
oxidative addition,’”, “1 with ethylene oxide under inert atmosphere gave a mixture of products, but under one atmosphere of CO, the products 2 a and 2 b were formed cleanly.
The reactions are complete within 1-2 days at 0 “C, and even
ambient CO, pressure is sufficient to give 2a and 2b as major
products.
Coupling of Epoxides to Pt“-Complexes
with Carbon Dioxide and the Structure of a
Cyclic Metallacarbonate**
By Khin-Than Aye, George Ferguson,* Alan .
I
Lough
and Richard J. Puddephatt *
The use of both epoxides and carbon dioxide as reagents
in organic synthesis has been increasing rapidly, and transition metal catalysts are often necessary.[‘ -61 One important
example is the coupling of epoxides with CO, to give cyclic
carbonate^;^^-^] and for electron rich catalysts such as
[M(PR,),], M = Ni or Pd, the general mechanism of Scheme
1 has been
The formation of oxametallacyclobutanes, B, by oxidative
addition of epoxides has been observed only with activated
epoxides such as tetracyanoethylene oxider7]or in a cryo-.
genic matrix.“] This is especially unfortunate since oxametallacyclobutanes are also thought to be key intermediates in the oxidation of alkenes to epoxides by cytochrome
P-450, and the catalytic step in which the epoxide is formed
by reductive elimination is obviously related to the reverse of
the first step in Scheme 1 (A -+B).[91We are therefore prompted to report the oxidative addition of some
[*] Dr. R. J. Puddephatt, K.-T. Aye
[**I
Department of Chemistry, University of Western Ontario
London N6A 5B7 (Canada)
Dr. G. Ferguson, Dr. A. J. Lough
Department of Chemistry, University of Guelph
Guelph N f G 2WI (Canada)
This work was supported by N.S.E.R.C. (Canada)
A n w i Chem. Ini. Ed. Engl. 28 (1989) No. 6
Me
Me
Cpd
r N
R
Cpd
r N
R
Za,
bpy
phen
bpy
phen
bpy
phen
H
H
Ph
Ph
CH,OPh
CH,OPh
3a’,
3b‘,
bpy
phen
bpy
phen
Ph
Ph
CH,OPh
CH,OPh
2b,
3a,
3b,
4a,
4b,
4a’,
4b’,
Figure 1 shows the crystal structure of 2b.[‘31The sixmembered platinum-containing heterocycle adopts a boat
conformation and there is a marked bowing of the 1,lOphenanthroline ring.
The analogous compounds 3a,b and 4a,b are formed
upon reaction of styrene oxide and 2-(phenoxymethyl)oxirane, respectively, with 1 a, b, and each was shown by NMR
to exist as a mixture of isomeric forms (for example, 3a/3a’)
which could not be separated. The NMR data, especially the
NMR data, showed clearly that the substituent R was in
the P-position to the platinium in all cases studied. Thus, the
a-carbon atom could easily be identified by the large value of
0 VCH Verlugsgesellschujf mbH. 0-6940
Weinheim, 1989
OS70-0833/89/0606-0767
$02..70/0
767
Table 1. Selected spectroscopic properties of complexes 2-4 [a].
Complex
'H NMR
IR
&(Mea) ,J(PtH) &(Meb) 'J(PtH) b(CH,") 6(CHP) i.(C=O)
[cm-'l
2a
2b
0.43
0.37
78
78
1.28
1.39
70
70
2.20
2.24
3.9
4.0
3a
3a'
3b
3b'
4a
0.39
0.32
0.35
0.44
76
74
77
76
1.43
1.41
1.54
1.59
68
68
68
68
2.2
5.0
1669
1630,
1670
1655
2.3
5.1
1649
0.48
77
1.46
68
2.3
4.3
1636.
1651
4 a'
4b
0.58
0.39
76
77
1.34
1.46
68
68
2.3
4.2
1647.
1666 [b]
4b'
0.48
76
1.35
68
&(Me") 'J(PtC)
'T NMR
b(Meb) 'J(PtC) &C=) h(CP) 'J(PtC')
'J(PtCP) 6(C =0)
3.02
15.48
698
734
- 2.88
- 2.00
698
721
19.2
17.5
64.6
61.9
663
69 3
2.67
3.19
15.59
15.6
- 15.39
719
719
720
720
719
-2.43
[c]
- 1.11
- 1.59
- 1.13
719
Lcl
720
[cl
719
26.3
24.6
25.9
18.4
74.9
[c]
79.4
[cl
75.8
701
666
696
Icl
701
187.2
[cl
[cl
[CI
187.3
-
15.57
15.53
719
722
-
3.08
1.75
683
718
16.3
18.1
[c]
72.1
647
707
[ci
158.5 [d]
-
19.25
720
- 3.51
720
16.1
[c]
687
157.7 Id]
-
-
[cl
45
56
187.6
[CI
[a] For pairs of isomers such as 3a/3a', the major isomer is arbitrarily assigned the structure 3a. The opposite assignment is possible also. [b] In 4 b * , prepared from
"CO,, i(C=O) = 1599, 1624cm-'. [c] Not resolved. [d] Measured for 4b*.
Table 2. Kinetic data for the reactions in acetone solution [a].
Complex
k,[L mol-' s-'1
Epoxide
AH*[kJ mol'']
AS*[J K - ' mol-'l
~-
PhOCH,CHCH,O
la
9.2 x
w5
48 +_ 2
-160 f 15
[a] k,, at 25 "C, is measured for disappearance of 1 a but, when measured in the presence of CO,, also applies to formation
of 3a/a' or 4a/a' (see text).
in Scheme 1,[5,101 and also suggests that the formation of
epoxides in transition metal catalysis[91may involve dipolar
intermediates.
Received: January 30, 1989 [Z 3147 IE]
German version: Angew. Chem. 101 (1989) 765
CAS Registry numbers:
I a, 52594-52-2; 1b, 52594-55-5; Za, 120610-86-8; 2b, 120610-87-9;
2b-0.5 C,H,, 120610-88-0;3a, 120610-82-4; 3a', 120709-21-9; 3b, 120610435; 3b', 120707-80-4; 4a, 120610-84-6; 4a', 120707-81-5; 4b, 120610-85-7; 4b',
120707-82-6; PhCHCH,O, 96-09-3; PhOCH,CHCH,O, 122-60-1; CO,, 12438-9; ethylene oxide, 75-21-8.
-
C.
w -C46
d c21
Fig. 1. Crystal structure of 2b. Important bond lengths [A] and angles ["I:
Pt - 0 1 5 21.144(9); 0 15 -C16 1.235(16); C 16- 0 1 7 1.236(16); C16 - 0 1 8
1.388(15); 018-C19 1.428(17); C19-C20 1.480(22); C20-Pt 2.034(14); 0 1 5 PI-C20 89.3(5).
lJpCc
= 663-707 Hz and was shown to be a CH, group in
every case by APT measurements (Table 1).
The kinetics of the reaction could be followed by monitoring the decay of the band due to 1 at 475 nm in the UVjVIS
spectrum. Using a large excess of epoxide, the reactions followed first order kinetics and the first order rate constants
were linearly dependent on the concentration of epoxide but
were independent of the concentration of CO,. Thus, overall
second order kinetics, first order in both platinum@) and
epoxide reagent, were established. This indicates that the
rate determining step involves oxidative addition of the epoxide (formation of B in Scheme 1) and that the subsequent
CO, insertion is fast. The activation parameters given in
Table 2 are typical of those expected for an S,2 oxidative
addition-mechanism, and suggest that a dipolar intermediate
[Me,(NN)Pt@- CH,CHRO@]is formed by nucleophilic attack by platinum(r1) on the least substituted carbon atom of
the epoxide steric effects are then responsible for the observed selectivity on formation of complexes 3 and 4. This
finding gives strong support for the mechanism of catalysis
768
Q VCH Verfagsgesefi.~chaf~
mbH. 0-6940 Wemheim. 1989
-
[I] D. Walther, Coord. Chem. Rev. 79 (1987) 135.
[2] A. Behr, U. Kanne, 1 Organumet. Chem. 309 (1986) 215; review: A. Behr,
Angew. Chem. 100 (1988) 681; Angew. Chem. Ini. Ed. Engl. 27 (1988) 661.
(31 B. M. Trost, S. R. Angle, 1 Am. Chem. Sor. 107 (1985) 6123.
[41 H. Kisch, R. Millini, I.-J. Wang, Chem. Eer. 119 (1986) 1090.
151 R. J. De Pasquale, 1 Chem. Soc. Chem. Commun. 1973, 157.
[6] T. Fujinanii, T. Suzuki, M. Kamiya, S. Fukuzawa, S. Sakai, Chem. Letr.
1985, 199.
[7] R. Schlodder, J. A. Ibers, M. Lenarda, M. Graziani, J. Am. Chem. SOC.96
(1974) 6893.
[8] Z. H. Kafafi, R. H. Hauge, W. E. Billups, J. L. Margrave, 1 Am. Chem.
SOC.109 (1987) 4775.
[9] J. T. Groves, Y. Watanabe, 1 Am. Chem. SOC.108 (1986) 507.
[lo1 D. P. Klein, J. C. Hayes, R. G. Bergman, J. Am. Chem. Soc. 110 (1988)
I
Chem. SOC.Chem.
3704. M. Farmer, M. A. Khan, K . M. Nicholas, .
Commun. 1988 1384.
1111 G. Ferguson, P. K. Monaghan, M. Parvez, R. J. Puddephatt,
Organomerallirs4 (1985) 1669.
[12] K.-T. Aye, D. Colpitts, G. Ferguson, R. J. Puddephatt, Organometallics 7
(1988) 1454.
[13] Crystallstructure data of 2b: C,,H,,N,O,Pt. 0.5C5H,,, M , = 1059.02,
monoclinic, space group C2/c (No. IS), a = 28.793(7) A, b = 11.823(3) A,
c = 12.473(2) A, fl = 93.30(2)", V = 4239.0 AY3, 2 = 8, pcalCd
= 1.66 g
cm-,, F(000) = 2056, Mo,, radiation (J. = 0.71073 A), p(MoK.) =
67.1 cm-'. Intensity data were measured at 23°C using an Enraf-Nonius
CAD4 diffractometer; Lorentz, polarization, and absorption corrections
were applied to the data. The structure was solved by the heavy atom
method. A loosely held n-pentane molecule of solvation with 0.5 occupancy was also found. Full matrix least-squares refinement, with hydrogens
allowed for as riding atoms, gave R , = 0.045 and R, = 0.063 for 2451
reflections with I 2 341). A final difference map was devoid of chemically
significant features. -The atomic coordinates for this work are available
on request from the Director of the Cambridge Crystallographic Data
Centre, University Chemical Laboratory, Lensfield Road, Cambridge
CB2 1 EW (UK). Any request should be accompanied by the full literature
citation for this communication.
0570-0833/89~0606-076R$02.SOIO
Angew. Chem. Inr. Ed. Engf. 28 (1989) No. 6
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structure, dioxide, cyclic, couplings, epoxide, ptii, metallacarbonate, complexes, carbon
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