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Oxidative Addition of the Central Bond of a Bicyclopentane System to Iron.

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Low-temperature photolysis of Fe(C0)5 in the presence
of tricyclo[3.2.0.02~']hept-3-ene (2)[31 affords the tetracarbony1 complex (3) as a yellow, thermolabile oil. On prolonged
photolysis, (3) decomposes smoothly with loss of carbon
monoxide and subsequent opening of bond a of the bicyclopentane unit to the n-ally1 o-complex (4), whose acyl derivative
can be isolated in crystalline form (21 %, m.p. 60°C). (In
the acyl derivative a carbonyl group is inserted in the F e X
bond.) We have been able to show that the ketone complex
( 6 ) (ca. 95 m. p. 87.5 "C) is formed from ( 4 ) in the presence
of free carbon monoxide at 20°C. If, however, ( 4 ) or its
acyl derivative is allowed to react with cyclohexene-Fe(C0)4~41
at -2O"C, the dinuclear carbene complex (7) is obtained
as main product (22 %, m. p. 98 "C) along with small amounts
of (6).
The ketone complex (6) is formed from a ketene precursor,
which can be trapped as the methyl ester with
From the stereochemistry of the trapped product we believe
that intermediary occurrence of the mononuclear carbene
complex ( 5 ) can be concluded. ( 5 ) is a plausible precursor
x,
?
of the carbene complex (7) in which the carbene carbon
is stabilized by two Fe(C0)3 groups.
Stepwise transformation of the hydrocarbon (2) into the
carbene complex (7) with cleavage of adjacent bondsc6]a
and b of the bicyclopentane unit afforded evidence for the
fragmentation of a metallacycle into a carbene and an olefin
component, as has been postulated in the case of olefin metathesis. The structures of the complexes ( 3 ) , ( 4 ) . ( 6 ) . and (7)
were determined on the basis of IR, 'H-NMR, and 13C-NMR
measurements. In addition, a crystal structure analysis was
carried out on the complex (7) (Fig. 1). The synthesis of
(7) is the first example of the preparation of a hydrocarboncarbene complex["*'] by metal-induced fragmentation of a
strained hydrocarbon.
The bond length (2.63 A) typical for carbene-bridged Fe-Fe
bonds['] is not further increased by the novel bridging of two
iron atoms by a n-bonded, almost planar 1,3-diene unit
(C1O=C11-C12=C7) and also by the carbene carbon (C13).
The Fe-Ccarbene
distances are unequal [I .977(3), 2.064(3)A]
but both lie within the expected range['']. Ccarbene
occupies an
apical position to the trigonal pyramidal Fe2 atom, and also
a position in the trigonal plane of the similar type Fel atom.
The same applies for the rc-bonded part of the molecule.
Hence different bonding (Fe-Cl0-CIl
and Fe2-C7-C12)
occurs in the n-bonded 1,3-diene system. The different FeCcarbene distances are also understandable. Finally, they make
a twisted arrangement of the two Fe(C0)3 groups possible.
Received: June 4, 1976 [Z 493a IE]
German version: Angew. Chem. 88, 640 (1976)
CAS Registry numbers:
Fe(CO),, 13463-40-6; ( I ) , 6006-21-9; (3)% 60064-64-4; (41. 60064-65-5; (6),
60064-66-6 ; f 7), 60064-67-7
[I]
Reactions of Strained C-C Single Bonds with Transition Metals, Part
14. This work was supported by t h e Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen 1ndustrie.-Part 13: R . Aurnanii, Chem.
Ber. IOY, 168 ( I 976).
C. P. Casey and 7: J . Burkhardr, J. Am. Chem. SOC. 96, 7809 (1974);
R. H . Crubba, P. L . Burk, and D. D. Carr, ibid. 97, 3265 (1975); 7:
J . Karz and J . McCiruiis, ibid. 97, 1593 (1975); M . 7: Mocella, M .
A . Busch. and E. L . Muetrerries. h i d . YB, 1284 (1976); cf. N. Calrleron,
E . A . Ofsread, and W A. Judy, Angew. Chem. 88, 433 (1976); Angew.
Chem. Int. Ed. Engl. 15, 401 (1976).
P. R. Story, J. Am. Chem. SOC.83, 3347 (1961).
R . Auniaiiri, Chem. Ber. 108, 1974 (1975).
R. Auriiawi and H . Wijrmaori, unpublished work.
W C . Dauheri and A . J . Kielbariia, Jr., J. Am. Chem. SOC. 94, 3669.
(1972); P. G. Gu.s.sinunand 7: J . Arkiris, ibid. 93, 4597 (1971); M . Sakai
and S. Masamme, h i d . 93, 4610 (1971).
B . Ceriiikaya, M. F. Lapperr, and K . Turner, J. Chem. SOC. Chem.
Commun. 1972.851; R. B. Schrock, J. Am. Chem. SOC.96,6797 (1974).
For methods of measurement and computation see: D. J . Brauer, C .
Kruger. P . J . Roberts, and Y.-H. Tsay, Chem. Ber. 107, 3706 (1974).
A list of parameters and structure amplitudes is available on request
from the authors ( C . K . ) .
0.S . Mills and A . D . Redhouse, J. Chem. SOC.IY68. 2282.
G. Huttiler and W Garrzke, Chem. Ber. 105, 2714 (1972); Y. Yariiurnoto,
K . Aoki. and H . Yarnazoki, J . Am. Chem. SOC.96, 2647 (1974).
OxidativeAddition of the Central Bond of a Bicyclopentane System to Iron[']
U
"03
[Z493al)
1
Oo5
Fig. I . Crystal structure of the dinuclear carbene complex (7). a = 19.273(3),
b = 13.858(l),c= 10.2347(7)A,spacegroupPbca, Z=8, MoK, radiation, 2940
reflections, of which 793 unobserved, R =0.0295 (R,=0.035) 181.
610
By Rudolf Aumann and Heinz Averbeck[']
An ex0 attack of the metal on the bridge of the bicyclic
systemc4]is postulated as the primary step in transition-metal
catalyzed isomerizations['I or cycloadditions of bicyclo[2.1 .O]pentanes to ole fin^[^]. We have now succeeded in isolating
stable iron complexes arising from such an attack.
[*] Priv.-Doz. Dr. R. Aumann and Dipl.-Chem. H. Averbeck
Organisch-Chemisches lnstitut der Universitat
Orkans-Ring 23, 4400 Miinster (Germany)
A~igvir.Chem Inr. Ed. €rig/. / Vol. I 5 (1976) No. 1 0
The light-induced reaction of hydrocarbons (I a) and ( 1 b )
with pentacarbonyliron (20°C, ether, Hg high-pressure lamp,
20 and 3 h, respectively) yields the colorless tetracarbonylferrapolycyclics ( 3 a ) (37 %, m. p. 115 "C, IR v ( M ) d O : 2099,
2040, 2026, 2016cm-', vC=O 1673cm-I) and ( 3 b ) (85 %
m.p. 9 6 T , IR v(M)--CZO: 2097, 2037, 2020, 2012cm-',
vC=O 1673cm- I), which further react with carbon monoxide
smoothly to the bis(acy1) compounds ( 4 a ) (ca. 95 %, slow
decomposition above 1OO"C, IR v ( M ) e O : 2108, 2052,
2050,2016cm-',vC=O 1634cm-') and ( 4 b ) (ca. 95 %,slow
decomposition above 85 "C, IR v(M)-CZO : 2106,2050,2047,
2013cm-', vC=O 1633 cm-I).
The methanotetrahydronaphthalene moiety of (3 a) could
be identified on the basis of experimentally determined proton
coupling constants refined by computer simulation (Fig. 1).
In accord with the proposed structure, on addition of E ~ ( f o d ) ~
to a C6H6 solution of the compound the resonance signals
at STMS=2.35,1.90, 3.23ppm are the most strongly shifted
to low field.
Fig. 1. 'H-NMR spectrum of ( 3 a ) (C,D,, 90MHz). Above: experimental,
below: computer-simulated spectrum using the quoted parameters (6 values,
coupling constants in Hz). S = solvent.
According to 'H-NMR measurements compounds ( 3b),
( 4 a ) , and ( 4 b ) contain the same structural elements as ( 3 a ) .
Received: June 4, 1976 [ Z 493b IE]
German version: Angew. Chem. 88, 641 (1976)
New Synthetic Entry to the Thiepin System.Benzo[d]thiepin and Dibenzo[bd]thiepin
By Kazuhiro Nakasuji, Koichi Kawamura, Toshio Ishihara,
and Ichiro Murata"]
Because of the ease of sulfur extrusion, extremely mild
conditions have to be employed for synthesis of the thiepin
system. We have previously found it possible to prepare benzo[b]thiepinr'l by Rh'-catalyzed isomerization of 6-thiatetracyclo[5.4.0.02~4.03~s]undeca-1(7),8,lO-triene~21,
a valence isomer of benzo[b]thiepin, under mild condition. We now
describe the synthesis of benzo[d]- and dibenzo[bd]thiepin
systems.
The readily accessible dibenzothiopyrylium tetrafluoroborate ( Z ) [ 3 1 reacts with ethyl lithiodia~oacetate[~]
in a 1 : 1 mixture of diethyl ether and tetrahydrofuran at - 120°C to form
diazo compound (2) [yellow oil, 32 % yield]. Treatment of
(2) with x-allylpalladium chloride dimer (5 mole %) in a
1 :2 mixture of chloroform and carbon tetrachloride at 0°C
and allowing to warm to room temperature for 2 h affords
the desired 6-ethoxycarbonyldibenzo[bd]thiepin (3)l5] quantitatively as a pale yellow oil. The spectra of (3) was fully
consistent with the thiepin structure. Despite the presence
of the thiepin skeleton, (3) is a stable compound and fails
to transform into 9-ethoxycarbonylphenanthrene even at elevated temperature in the presence of triphenylphosphane.
Alkaline hydrolysis of (3) gives the free acid ( 4 ) [pale yellow
plates, m. p. 220°C (dec.), 93 % yield]. Decarboxylation of
( 4 ) with copper in quinoline at 150°C for 30min leads to
the parent dibenzo[bd$hiepin ( 5 ) (colorless plates, m. p. 82
to 83°C) which on thermolysis in refluxing xylene in the
presence of triphenylphosphane for 1 day furnishes phenanthrene.
The synthetic utility of the ring enlargement reaction was
illustrated by its application to the diazo compound (7) [yellow oil, 53% yield] which was prepared from benzothiopyrylium tetrafluoroborate (6)[61.When (7) was subjected to
reaction with n-allylpalladium chloride dimer under the same
condition as in the case of ( 2 ) , the product isolated was
CAS Registry numbers:
( I a ) , 7213-64-1; (1 b ) , 279.18-5; ( 3 u ) , 60064-56-4; ( 3 b ) , 60064-57-5; ( 4 a ) ,
60064-58-6; ( 4 b ) , 60064-59-7; Fe(CO),, 13463-40-6
[l] Reactions of Strained C-C Single Bonds wlth Transition Metals, Part
15. This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrk-Part
14: R. Aumann, H .
Wormann, and C . Kriiger, Angew. Chem. 88,640 (1976); Angew. Chem.
Int. Ed. Engl. I S , 609 (1976).
[2] a) K . B. Wiberg and K . C . Bishop, I l l , Tetrahedron Lett. 1973, 2727;
b) M. A. McKinney and S . K . Chou, ibid. 1974, 1145; c ) P . G. Gassman,
7:J . Atkin,, and J . 7: Lumb, J. Am. Chem. SOC.94, 7757 (1972).
[3] R. Noyori, E Kumagai, and H . Takupi, J. Am. Chem. SOC. 96, 634
(1974).
[4] A strain energy of ca. 47 kcal/mol should be released on cleavage of
this bond; cf. R. B. Turner, P . Goebel, B. J . Mallon, W. u. E . Doering,
J . F . Coburn, Jr., and M . Pomerantz, J. Am. Chem. SOC. 90, 4315 (1968);
S. Chang, D . McNally, S . Shary-Trhrarlr, M . J . Hickey, and R. H . Boyd,
ibid. 92, 3109 (1970).
Angrw. Chem. I n r . Ed. Engl. 1 !-+)I. I 5 ( 1 9 7 6 ) No. 10
[*] Dr. K. Nakasuji. K.Kawamura. T. Ishlhara, and Prof. Dr. 1. Murata[+]
['I
Department of Chemistry, Faculty of Science, Osaka University
Toyonaka, Osaka 560 (Japan)
To whom correspondence should be addressed.
61 1
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