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Novel Carbonylcyclopropane Dimers and TrimersЧFree Ketenes or Organometallic Intermediates.

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cyclopentadienyl ligand. O n the basis of reference data,[']
and the fact that couplings to moieties which are oriented
in the eclipsed position with respect to the free electron
pair of the phosphorus atom are larger, a 2-configuration
must be assumed for 3. This finding is confirmed by the Xray structure analysis of 3 at - 162°C (Fig. l)."" The P=C
bond length (170.114) pm) lies in the range (168 to 172 pm)
characteristic for phosphaalkenes.["I The iron atom lies in
a plane with the atoms P, C1 and 0 1 and is linked to the
phosphorus via a single bond (229.8(1) pm). The C l - 0 1
distance (136.515) pm) is markedly shorter than the length
calculated for a C(spz)O single bond (141 pm).['21The angle at the phosphorus is 113.8(2)", while that at 0 1 is considerably widened (144.7(3)"). Complex 3 differs from the
phosphavinyl complex 4 in that the lone pair on the phosphorus is not required for electronic saturation of the metal; hence, 3 can be regarded as a transition metal-substituted phosphaalkene or as a n q'(Fe-P)-phosphaalkenyl
complex.
Received: March I , 1985;
revised: April 12, 1985 [Z 1199 IE]
German version: Angew. Chem. 97 (1985) 583
CAS Registry numbers:
1 , 76586-94-2; 3, 96729-32-7; pivaloyl chloride, 3282-30-2.
[I 11 a) R. Appel, V. Barth, F. Knoch, Chem. Ber. 116 (1983) 938; b) R. Appel,
M. Halstenberg, F. Knoch, H. Kunze, ibrd. 115 (1982) 2371; c) B. Bak,
N. A. Kristiansen, H. Svanholt, Acta Chem. Scand. A 3 6 (1982) I : d) R.
Appel, F. Knoch, B. Laubach, R. Severs, Chem. Ber. 116 (1983) 1873; e)
G. Becker, 0. Mundt, Z . Anorg. ANg. Chem. 443 (1978) 53; f , T. A. van
der Knaap, T. C. Klebach, F. Visser, F. Bickelhaupt, P. Ros, E. J. Baerends, C. H. Stam, M. Konijn, Tetrahedron 40 (1984) 765.
[12] U. Schubert, H. Fischer, P. Hofmann, K. Weiss, K. H. Dotz, F. R.
Kreissl: Tran.rition Mela1 Carbene Complexes, Verlag Chemie, Weinheim
1983, p. 77.
Novel Carbonylcyclopropane Dimers and TrimersFree Ketenes or Organometallic Intermediates?**
By Jan-Michael Wurff and H. M . R . Hoffmann*
We have previously reported on the preparation of dispiro[2.1.2.l]octane-4,8-dionesvia dehalogenation of I bromocyclopropanecarbonyl chlorides with zinc in tetrahydrofuran (THF), e.g. 1 +2.[']
We have now investigated other 1-bromocyclopropanecarbonyl chlorides and also expanded the experimental
conditions for dehalogenation, by using magnesium in addition to zinc as a reducing agent and acetonitrile in addition to tetrahydrofuran as a solvent.
For example, when magnesium was added to 1 in T H F
and the reaction solution was scanned by IR after 5 min,
the band of the acid chloride 1 (1780 c m - ' ) and that of 2
(1708 cm-') were visible in a ratio of 1 :1 in addition to a
new absorption at 2115 c m - ' , which we assign to the cumulated system of double bonds of the free carbonylcyclopropane 3.12]This band had an intensity of ca. 10% with respect to the dominating acid chloride band and had disappeared after ca. 10 min. Hence, permethylated 3 has a considerably longer lifetime than parent carbonylcyclopropane, which stays monomeric at liquid nitrogen temperatures only.131Magnesium and T H F are also optimum for
preparing the cyclic dimer 2 (70-75% isolated yield) from
[I] Summaries: a) R. Appel, F. Knoll, I. Ruppert, Angew. Chem. 93 (1981)
771 : Angew. Chem. I n f . Ed. Engl. 20 (1981) 731; b) G. Becker, W. Becker, 0. Mundt, Phosphorus Sulfur 14 (1983) 267; c) A. H. Cowley, Polyhedron 3 (1984) 389.
12) a) 0. J . Scherer, Nachr. Chem. Tech. Lab. 32 (1984) 582; b) 0. J. Scherer,
R. Walter, W. S. Sheldrick, Angew. Chern. 97 (1985) 132; Angew. Chern.
I n t . Ed. Engl. 24 (1985) 115.
131 a) R. H. Neilson, R. J. Thoma, 1. Vickovic, W. A. Watson, Orgnnomelallics 3 (1984) 1132; b) H. Werner, W. Paul, R. Zolk, Angew. Chem. 96
(1984) 616; Angew. Chem. I n f . Ed. Engl. 23 (1984) 626, and references
cited therein; c) S. Holland, C. Charrier, F. Mathey, J. Fischer, A.
Mitschler, J. Am. Chem. Soc. 106 (1984) 826; d) K. Knoll, G. Huttner,
1.
M. Wasiucionek, L. Zsolnai, Angew. Chem. 96 (1984) 708; Angew. Chern.
In,. Ed. Engl. 23 (1984) 739; e) H. W. Kroto, S. I. Klein, M. F. Meidine,
J. F. Nixon, R. K. Harris, K. J. Packer, P. Reams, J . Organornet. Chem.
280 (1985) 281, and references cited therein.
[4] L. Weber, K. Reizig, Angew. Chem. 97 (1985) 53; Angew. Chem. Int. Ed.
Engl. 24 (1985) 53.
[S] A. H. Cowley, N. C. Norman, S. Quashie, J . Am. Chem. SOC.106 (1984)
1
2
3
5007.
[6] G. Becker, 2. Anorg. Allg. Chem. 423 (1976) 242.
[7] a) H. Schafer, 2. Anorg. Allg. Chem. 467 (1981) 105; b) L. Weber, K.
Reizig, Z. Naturforsch. 8 3 9 (1984) 1350.
With zinc as metal and absolute acetonitrile as solvent
[XI Experimental: 3: A solution of pivaloyl chloride (0.849 g, 7.05 mmol) in
not only 2 was formed, but also dodecamethylhexahydro100 mL of tetrahydrofuran ( T H Q was added dropwise in 1 h at 35°C to
a solution of 1 (2.496 g, 7.05 mmol) in a mixture of pentane (25 mL) and
benzo[l,2-b :3,4-b' :5,6-b'ltrifuran 4 (2 :4 = 77 :23 ; 56%
T H F (75 mL). After removal of the solvent, the oily, brown residue was
combined yield).[41
extracted with ca. SO mL of pentane. The filtered pentane extract was
evaporated to ca. 20 mL and allowed to stand at -78°C for 24 h. A precipitate settled out. The mother liquor was drawn off with a pipette and
the precipitate was recrystallized from a little pentane at -25°C. This
furnished 0.590 g (23%) of brownish-red crystalline 3, m.p. 61 "C.- ' H
ZnlMeCN
NMR (200 MHz, C6D6. 22°C): 6=0.44 (s, 9 H , OSi(Me,),), 1.43 (d,
1 - 2
+
4J(PH)=2.2 Hz,9H,tBu),4.15(d,'J(PH)=2.2Hz,5H,C,H,).-'3C('H}
reflux
NMR (ChD6, 22°C): 6 = 2 . 8 (s, OSiMel), 31.1 (d, 'J(PC)= 14.7 Hz,
C(CHI),), 45.4 (d, 'J(PC)=23.6 Hz, C(CH,),), 86.0 (d, *J(PC)=3.8 Hz,
C,H,), 213.5 (d, 'J(PC)=95.7 Hz, P=C), 215.4 (s, Fe-C-O).--?'P('H)
NMR (C6D6,22°C): 6=215.2.-1R (cyclopentane): 2018 s, 1963s c m - '
4
(v(CO)).-EI-MS (Varian MAT 312. 70 eV. 70°C): 366 ( M + l 338
( M +-CO), 310 ( M i -2CO), 238 [(C,H,)FeP(H)C(O)tBu+], 210
A rational precursor of 4 is the novel trispiro compound
[(C,H,)FeP(H)(tBn)'], 195 ((C,H,)FeP(H)[C(CH,),J+j, 73 (SiMe :), 57
(tBu+).
56 ( F e + ),
5a. which. on contact with the zinc halide generated. will
~
~
,
[9] G. Becker, 0. Mundt, G. Uhl, Z. Anorg. Allg. Chem. 517 (1984) 89.
[lo] Space group: P2,/n; a=673.4(2), b=3147.6(10), r=842.1(4) pm,
[*] Prof. H. M. R. Hoffmann, Dr. J.-M. Wulff
/3=97.91(3)", V = 1.7694(11)x lo9 pm'; Z = 4 , R=0.061. Further details
lnstitut fur Organische Chemie der Universitat
of the crystal structure investigation are available on request from the
Schneiderberg 1 B, D-3000 Hannover (FRG)
Fachinformationszentrum Energie Physik Mathematik, D-7514 Eggenstein-Leopoldshafen 2, on quoting the depository number C S D 51 374,
[**I We thank the Fonds der Chemischen Industrie for support of this
the authors names, and the full citation of the journal.
work.
-
Angew Chew. Inl. Ed. Etigl. 24 11985) N o . 7
0 VCH Verlugsgesellschaft mbH, D-6940 Weinheirn. 1985
0570-0833/85/0707-0605 $ 02.50/0
605
first form the tertiary homoallylic cation 5b and eventually
the arene 4.
5a
5b
5c
Since 1,3,5-trihydroxybenzene (phloroglucinol) is known
to exhibit ketonic properties, we felt that trispirotriketones
other than the hypothetical permethylated 5a might actually be isolable. Surprisingly, dehalogenation of 6[41with
magnesium in acetonitrile gave the p-ketoacid chlorides
8a-d as a mixture of four stereoisomers. Dimers of the
dispiro[2. 1.2.l]octane-4,8-dione type (cf. 9a-d) were
formed only in traces (GC). Attempts to cyclize 8 to 9 with
zinc in TH F and acetonitrile remained unsuccessful.
The major trimer lOaL4Ihad an IR spectrum identical to
that of lob, showing, inter aha, a carbonyl band at 1670
cm-'.
While there can be little doubt that free carbonylcyclopropanes occur on reaction with magnesium in tetrahydrofuran (cf. 3), the formation of coupling products such as
8a-d in acetonitrile is in better agreement with organometallic intermediates such as I-chloroformylcyclopropyl
Grignard compounds 7a, b. Similarly, since the formation
of cyclic trimers of the 1,3,5-cyclohexanetrione type (cf.
10a, b) is unknown in conventional ketene chemistryL6]we
propose that a corresponding organozinc intermediate is
involved in the cyclotrimerization. The hypothetical 1 chloroformylcyclopropylmetal compounds should be both
nucleophilic and electrophilic and thus enter into multiple
coupling, including polymerization. Their finite existence
can be ascribed to several factors, including covalency of
the cyclopropylmetal bond, solvation-or lack thereof-of
the metal atom and impeded enolate resonance due to developing methylenecyclopropane and carbonylcyclopropane strain.
Received: April I , 1985 [Z 1248 IE]
German version: Angew. Chem. 97 (1985) 597
MgIMeCN
COCl
CAS Registry numbers:
1, 81359-22-0; 2 , 81359-25-3; 3, 96929-29-2; 4, 96929-30-5; 6 , 96929-31-6;
Sa, 96929-32-7: Sb, 96997-72-7: SC,96997-73-8; 8d, 96997-74-9; 9a, 9692933-8; 9b, 96997-75-0; 9c, 96997-76-1 ; 9d, 96997-77-2; IOa, 97058-15-6: lob,
96929-34-9; Mg, 7439-95-4: Zn, 7440-66-6; I,l-dibromo-2-(trimethylsilyl)cyclopropane, 17544-73-9; cis-l-bromo-~trimethylsilyl)cyclopropanecarboxylic
acid, 96929-35-0; trans-l-bromo-2-(trimethylsilyl)cyclopropanecarboxylic
acid, 96929-36-1.
reflux
6
8a
8b
0
0
ClCO B r
ClCO B r
SiMe,
8d
8c
However, dehalogenation of 6 with zinc in boiling acetonitrile gave four stereoisomeric dimers, 9a-d,Is1 and two
stereoisomeric trimers, 10a, b (60% combined yield ;
9 : 10 = 88 : 12; 10a : 10b = 2 : 1). After sublimation of the
dimers 9a-d the remaining trimer fraction was separated
by chromatography (basic A1,03, pentane/ether= 10 : I).
The cyclic trimer, formed in only small amounts, could
be identified clearly as 10b by virtue of its C 3 axis. In the
90-MHz and 270-MHz 'H-NMR spectra 10b showed only
one Me& signal at 6 = 0.09 and only one ABM system.'41
0
ZnlMeCN
6reflux
9a-d
(4 stereoisomers)
siivr,
S i M e3
Y
M?,Si
10 a
606
10b
0 V C H Verlagsgesellschafi mbH, 0-6940 Weinheim, I985
[ I ] H. M. R. Hoffmann, J. M. Wulff, A. Kiitz, R. Wartchow, Angew. Chem.
94 (1982) 79; Angew. Chem. h t . Ed. Engl. 21 (1982) 83; Angew. Chem.
Suppl. 1982, 17.
1.11 Carbonylcyclopropane itself shows IR bands at 2125 and 2145 cm ~' [3a].
6-Carbanyibicyclol3. I.0Ihexane shows an TR band at 2126 cm - ' [C. Wentrup, G. Gross, A. Maquestiau, R. Flammang, Angew. Chem. 95 (1983)
551: Angew. Chem. Inr. Ed. Engl. 22 (1983) 542).
[31 a) G. J. Baxter, R. F. C. Brown, F. W. Eastwood, K. J. Harrington, Tetrahedron Len. 1975. 4283: J. L. Ripoll, Tetrahedron 33 (1977) 389. b) The
much greater kinetic stability of di-(err-butylketene compared with the
parent ketene CH,CO is well documented: M. S. Newman, A. Arkell, T.
Fukunaga, J. An]. Chem. Sor. 82 (1960) 2498.
[41 4 has Cjh symmetry: IR (KBr): 2980 (m), 2960 (m), 2930 (m), 2870 (w),
1640 (5, C=C), 1340 (s), 1390 (w), 1375 (w), 1365 (m). 1245 (m), 1225 (w).
I170 (m), 1145 (w), 1130 (w), 1065 (vs), 960 (m), 940 (w), 850 (w). 830 (m).
'H-NMR (CDCI,): 6= 1.19 (5, l8H, 6CH3), 1.26 (s, 18H, 6CH.3). "CNMR (CDCI,): 6=23.05 (9. CHj), 23.17 (4, CH,), 44.95 (s, Me,C-C),
91.45 (s, Me,C-O), 111.08 (s, C=C-0), 153.48 (s, C=C-O).-Preparation of 6 : I,l-Dibromo-2-trimethylsilylcyclopropane
(5.44 g, 20 mmol)
(prepared by addition of dibromocarbene to trimethylvinylsilane) was
dissolved in T H F (100 mL), Et2O (20 mL), and pentane (20 mL). After addition of 12.5 m L of a 1 . 6 ~solution of n-butyllithium (20 mmol) at
- 125°C for 15 min, the mixture was stirred for 30 min at
110°C and
carboxylated by treatment with an excess of divided solid C 0 2 . Work-up
gave a mixture (40 :60, GC) of em-bromo and endo-bromocarboxylic
acids (1.65 g, 35%). After recrystallization from ether/pentane, I-bromo2-trimethylsilylcyclopropanecarboxylicacid (bromine cis to Me,Si group)
was isolated as a white solid, m.p. 135"C, which was converted into 6 by
treatment with SOC12.-lOb: 90- and 270-MHz ' H N M R , ABM system
centered at 6 = 1.50, 2.03 and 2.23, with J(AB)= 1 Hz, J(AM)= 10.5 Hz
and J(BM)= 11.5 Hz. I3C NMR (CDCI,): 6=203.6 (s, C=O), 45.8 (s.
spiro C), 38.9 (m. CH,), 32.7 (m, CH), -0.8 (9, SiMe,).- 1Oa: ' H NMR
(270 MHz, CDCI,): S=0.075, 0.079, 0.081 (3s, 27H, 3SiMe,), 1.44, 1.49,
1.56 (M part of ABM system, 3 H), 1.94, 1.99, 2.06 (A part of ABM system, 3H), 2.11, 2.19, 2.29 ( B part of ABM system, 3 H ) : J(AB)=I Hz,
J(AM)= 10.5 Hz, J(BM)= 11.5 Hz. Due to partial overlapping of signals
only 12 of the expected 15 signals were observed in the ' ) C NMR spectrum: 6=203.6, 203.5 (2s, C=O, only 2 signals), 45.9,45.7,45.6 (3s, spiro
C), 38.0, 37.1, 36.7 (3 m. CHI), 33.3, 32.7 (2m, CH, only 2 signals), -0.7,
-0.8 (2q, SiMe,, only 2 signals).
I S ) The least hindered dimer (Me& groups anri. trans) was formed preferentially (57%), the sterically most hindered dimer (MeiSi groups syn, cis)
was formed in least amount (3.1%).
[6] S. Patai (ed.): The Chemistry ofKerenes. Allenes and Related Compounds,
Purr? I and 2. Wiley, Chichester 1980; D. Seebach in Houben-Weyl:
Methoden der Organischen Chemie. Yo/. 4 / 4 , Thieme, Stuttgart 1971, p.
174: W. T. Brady, Tetrahedron 37 (1981) 2949.
0570-0833/85/0707-0606 $ OLW/O
~
Angew. Chem Int. Ed. Engl. 24 (1985) No. 7
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