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Intramolecular Carbene-Carbon Monoxide Coupling in Chromium and Tungsten Complexes.

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elimination rather than to a lower reactivity of [Ru] towards an sp3-C-H bond. 5d-Metals (such as, e.g.. iridium)
form more stable M-H and M-C bonds than 4d-metals
(such as, e. g., ruthenium), another finding consistent with
the results published recently by Jones and FehedSb1.We
assume that a higher charge density at the central atom
caused by the ligand in addition to the greater number of
electrons of the metal effects stabilization of the M-H and
M-C bonds. This hypothesis is supported by the fact that
the complex 7 (with the better donor C6Me6 compared to
C&),
unlike 3, does not react with C6D6 to give
(C6Me6)RuD(C6D,)(PMe3) even on prolonged heating at
50°C.
Received: July 13, 1983 [Z 465 IE]
German version: Angew. Chem. 95 (1983) 916
CAS Registry numbers:
1, 85413-08-7; 2, 87556-34-1; 3, 87556-30-9; 4 (isomer l), 87556-31-8; 4
(isomer 2), 87585-20-4; 5, 82498-40-6; 6, 87556-32-9; 7, 87556-33-0.
[I] a) G. W. Parshall: Homogeneous Caralpis, Wiley-Interscience, New York
1980; b) J. Chatt, J. M. Davidson, J. Chem. SOC.1965, 843; c) M. L. H.
Green, P. J. Knowles, J. Chem. SOC.Chem. Commun. 1970, 1677; M. L.
H. Green, G. Gianotti, ibid. 1972. 1114; M. Berry, K. Elmitt, M. L. H.
Green, J. Chem. Sac. Dalton Trans. 1979, 1950.
[21 a) A. H. Janowicz, R. G. Bergman, J. A m . Chem. SOC.104 (1982) 352; IOS
(1983) 3929; b) J. K. Hoyano, W. A. G. Graham, ibid. 104 (1982) 3723.
[3] a) H. Werner, H. KIetzin, J. Organornet. Chem. 243 (1983) C59; b) ibid.
228 (1982) 289.
[4] All the compounds gave correct elemental analyses. NMR in CaD6 (4 in
C6Di2)at room temperature. 2: yellow oil; 'H-NMR: 6(C6H4)=7.56 (m),
6.78 (m),6(CcjH6)=5.00 (m), 6(CsHdCH3)=2.33 ( S ) , 6(PCHCH3)= 1.80
(m). 6(PCHCH3)=1.00 and 0.97 (dd, JpH=12.8, JHH=6.8 Hz),
& R u m = -9.06(d,JpH=50.0 Hz); "P-NMR:6=70.18 (s). 3:yellowoil;
'H-NMR: 6(C6ff5)=7.81 (m), 6.94 (m), 6(C6H6)=5.00 (m),
= 12.2,
6(PCHCH3)= 1.80 (m), G(PCHCH3)= 1.00 and 0.96 (dd, JpH
J ~ ~ s 6Hz),
. 4 &(Rum= -9.00 (d, JPH=SO.OHZ); "P-NMR: 6=69.77
(s). 4 : yellow oil (obtained as 70 :30-mixture of two diastereomers); 'HNMR: 6(C&6)=4.98 (m), 6(PCHCH,)= 1.69 (m), 6(PCHCH,)= 1.15
(m),G(RuH)= -8.16 and -8.63 (dd, JpH=43.0,JHH=3.2Hz), signals of
C'H2, C2H and C2CH3masked by PiPrz signals; "C-NMR (400 MHz,
10°C): 6(CsH6)=82.88 (s), 82.64 (s), 6(C')= - 10.74 (d, Jpc=45.9 Hz),
-7.16 (d, Jpcx42.3 Hz), 6(C2)=42.80 (d, Jpc=35.9 Hz), 44.85 (d,
Jpc=32.6 Hz). 6 : bright yellow crystals, decomp.> 78°C; 'H-NMR:
6(C,H4)=6.95 (m), 6(C6H4CH,)=2.33 (s), 6(C6Me6)= 1.93 (m),
6(PMe3)=0.95 (d, J p ~ = 8 . 5Hz),G(RuH)= -lO.SO(d, JpH=58.0 Hz); "PNMR: 6=6.41 (s). 7 : bright yellow crystals, decomp.>52"C; 'H-NMR:
6(C6H5)=7.33 (m), 6(C&fe6)=1.93 (m), G(PMe3)=0.95 (d, JpH=8.5 Hz),
&(Ruff)= -10.80 (d, J p ~ = 5 8 . 0Hz); 3'P-NMR: 6=6.58 (s).
151 a) W. D. Jones, F. J. Feher, J. A m . Chem. SOC.104 (1982) 4240; b) Organometallics 2 (1983) 562.
Intramolecular Carbene-Carbon Monoxide Coupling
in Chromium and Tungsten Complexes**
By Helmut Fixher*
Transition-metal induced CC bond-forming reactions
between CO and CR2 as well as between two CR2 moieties
have recently been proposed as possible steps in the Fischer-Tropsch synthesis. Bond formation between two CR2 ligands giving the dimer is a reaction characteristic of the
decomposition of carbene complexes: thermolysis of pen[*] Dr. H. Fischer
[**I
Anorganisch-chemisches
Institut der Technischen
Universitlt
Miinchen
Lichtenbergstrasse 4, D-8046 Garching (Germany)
Kinetic and Mechanistic Studies of Reactions of Transition-Metal Complexes, Part 14. This work was supported by the Deutsche Forschungsgemeinschaft. Priv.-Doz. Dr. F. R. Kreissl is thanked for the mass spectra.-Part 13: H. Fischer, E. 0. Fischer, R. Cai, D. Himmelreich, Chem.
Ber. 116 (1983) 1009.
874
0 Verlag Chemie GmbH. 6940 Weinheim. 1983
tacarbonyl(dipheny1carbene)tungsten 1 in refluxing heptane gives diphenylmethane 2 (10%) and tetraphenylethylene 3 (35%)"'. Among the organic products formed in the
mild thermolysis (20 to 50°C) of dilute solutions of 1
5x
to
mol/L) in polar or nonpolar solvents
(methylcyclohexane, toluene, dibutyl ether, 1,1,2-trichloroethane), in addition to 2 and 3 the product of CO-carbene coupling, diphenylketene 4 was detected in 20 to 70%
yield.
0
c
IJ
OC-W=C,
Cl'
o c
o
/Ph
Ph
Ph
Ph\
+
CH2
Pk:
+
Ph
lC=Cl
Ph
Ph
+
Ph\
/C=C=O
Ph
+
W(CO),+..
0
1
2
3
4
Diphenylketene was identified by comparison of its
spectra and its gas chromatogram with those of an authentic sample. At 50°C the half-life of 1 upon thermolysis in
1,1,2-trichloroethane is cu. 1400 s ([ l]0=0.008 mol/L).
With increasing concentration of the complex the reaction
rate increases slightly, whereas the yield of 4 decreases.
The thermolysis proceeds significantly slower in nonpolar
solvents than in polar. The reaction rate is reduced by the
presence of free CO in the solvent, particularly with nonpolar solvents. The chromium compound analogous to 1
reacts at least 50 times faster or under even milder conditions (half-life at 32"C, cu. 150 s). 4 is also formed from
the chromium complex by warming the solid substance in
oucuo (32"C, cu. 15 min). If the thermolysis of 1 under
I3CO is interrupted after cu. 25% conversion and the resultant 4 subsequently converted by treatment with methanol
into methyl diphenylacetate, mass spectroscopic analysis
of this ester indicates that I3CO is not incorporated into 4.
The CO group in the diphenylketene therefore originates
from the coordination sphere of the metal. Hexacarbonyltungsten, which is formed simultaneously, consists of a
mixture of ('2co)6-,('3co)"w (n=O to 4).
These results together with the results of kinetic studies
and the determination of the yield of 4 as a function of the
concentration of complex indicate that bond formation between a CO and the CPh2 ligand to give diphenylketene
proceeds intramoleculurly in a (CO),W(CPh,) complex
fragment produced by elimination of CO. In contrast, the
dimerization of the carbene ligand to tetraphenylethylene
presumably proceeds via a dinuclear intermediate.
Whether this intermediate dissociates directly, eliminating
olefin 3,or whether carbene transfer occurs to form a biscarbene complex from which 3 cleaves off cannot yet be
clarified. A corresponding bimolecular mechanism involving formation of a biscarbene complex has been proposed
for the thermolysis of pentacarbonyl(2-oxacyclopentylidene)chromium on the basis of kinetic studies1']. Scheme 1
may, therefore, be the best description of the course of the
thermolysis of 1.
Tricarbonyl(viny1carbene)iron complexes related to intermediate B are known. In the presence of CO at room
temperature, they insert CO into the metal-carbene carbon
Carbonylation of a diphenylcarbene- to afford a diphenylketene-ligand has previously been reported using manganese complexes; however, the reaction is slower and requires high pre~sure'~].
In contrast to these reactions, the
coupling of coordinated CO and CPh2 in 1 and the analogous chromium complex occurs spontaneously under very
0570-0833/83/1111-0874 $02.50/0
Angew. Chem. In[. Ed. Engl. 22 (1983) No. I 1
,Ph
(CO)5M-C,
Ph
I
-{
lPhjPh
-co
i-1
(C0)4M=C,
Ph\
/
Ph
+"
A
Ph
+...
/C=C,
Ph
3
J
C=C=O
+
M(C0)s
C
Scheme I
mild conditions without having to be induced by external
CO or other nucleophiles. These results corroborate the
mechanism proposed by Riichardt and Schrauzer for the
formation of ketenes in the reaction of diazoalkanes with
tetra~arbonylnickel[~"'.The ready interconversion (carbene)carbonyl complex/ketene complex (corresponding to
A + C) could be proved in an iron system by labeling exp e r i m e n t ~ and
~ ~ ~corresponds
~,
to the predictions of MO
calculations['"I.
For chromium and tungsten compounds, both types of
C-C coupling reactions-carbene-carbene and CO-carbene-have now been shown to occur simultaneously and
at the same complex.
report here a seven-step synthesis of the racemic 6-deoxycarminornycinone 2at***]from the readily accessible aloeemodin 5a.
The acetal of the keto bromide 7, which can be prepared
in three stages from 5a (70% yield)"'], surprisingly does
not cyclize to the linearly condensed naphthacenequinone
3a after reduction to the leuco form, but to a benzo[a]anthracene['81. Since aldehydes always add to phenols at the
ortho-position to the OH group, we synthesized the aldehyde 9 in order to study its cyclization.
Bromide 7 reacts with silver acetate in glacial acetic acid
to afford a product (87%) which, according to the 'HNMR spectrum (CDCI,), is a mixture of the keto alcohol
l l a and the cyclic hemiacetal l l b . The keto aldehyde 9
(55%) is formed by oxidation of l l a / l l b . Reduction of aldehyde 9 with alkaline dithionite to give leuco-anthraquinone is followed within a few minutes by the spontaneous
cyclization to the 3 : 1 mixture of alcohols 12 and 13 (80%).
The cis- and trans-compounds 12 and 13, respectively, can
be readily separated by chromatography. Because of the
trans-diaxial interaction between 9(a)-H and 10-H the
structure of 12 can be assigned straightforwardly from the
'H-NMR spectrum. The synthesis of 2a is completed by
hydroxylating C-8; for this purpose, the stereoisomers 12
and 13 need not be separated.
0
?H
OH 0
OH 0 OH
Received: July 13, 1983;
revised: August 23, 1983 [Z 463 IE]
German version: Angew. Chem. 95 (1983) 913
[I] C. P. Casey, T. J. Burkhardt, J. Am. Chem. Soc. 95 (1973) 5833.
I21 C. P. Casey, R. L. Anderson, J. Chem. Soe. Chem. Commun. 1975, 895.
[3] T. Mitsudo, T. Sasaki, Y. Watanabe, Y. Takegami, S. Nishigaki, K. Nakatsu, J. Chem. SOC.Chem. Commun. 1978, 252; J. mimes, E. Weiss, Angew. Chem. 94 (1982) 207; Angew. Chem. Int. Ed. Engl. 21 (1982) 205; Angew. Chem. Suppl. 1982,'477.
141 W. A. Herrmann, J. Plank, Angew. Chem. 90 (1978) 555; Angew. Chem.
Int. Ed. Enql. 17 (1978) 525.
[ 5 ] a) C. Riichardt, G. N. Schrauzer, Chem. Be?. 93 (1960) 1840; b) W. A.
Herrmann, J. Gimeno, J. Weichmann, M. L. Ziegler, B. Balbach, J . Organomet. Chem. 213 (1981) C26; c) P. Hofmann, L. A. Perez-Moya, unpublished results.
e
OH 0
lla
OH 0
[**I
[***I
Prof. Dr. K. Krohn, Dr. B. Sarstedt
Institut fur Organische Chemie der Technischen Universitat
Schieinitzstrasse, D-3300 Braunschweig (Germany)
Synthetic Anthracyclinones, Part 24. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. Prof. F. Areamone (Farmitalia, Milano) is thanked for a sample
of 6-deoxydaunomycinone.-Part 23: K. Krohn, Liebigs Ann. Chem..
in press.
The numbering follows IUPAC Nomenclature.
Anqew. Chem. Int. Ed. Engl. 22 (1983) No. I 1
Br.
Q$J-?J)"
/
llb
OH
0
2a,
2b,
3a,
12,
13,
14,
9
Facile Synthesis of the
['I
OH
OH 0 OH
OH
OH
( & )-6-Deoxycarminomycinone from Aloe-Emodin**
By Karsten Krohn* and Burkhard Sarstedt
Dedicated to Professor Hans Brockmann on the occasion
of his 80th birthday
The daunorubicin group of antitumour antibiotics[51has
recently been extended by the discovery of the possibly
less toxic analogous 6-deoxy compounds (e. g. 2b)"I. We
9
0
..._..
R'
R'
= R 2 = H, R3 = R4 = OH
= CH,,R Z = H,R 3 = R 4 =
R'-K4 = H
R' = R3 = H4 = H , RZ = OH
R' = R 2 = R4 = H, R3 = OH
R' = R3 = H,RZ = R4 = O H
OH
Oxygenation of the enolate obtained from 12/13 (dimethy1 formarnide, potassium tert-butoxide, - 20°C) in the
presence of triethyl phosphite leads to a mixture of ( + ) - 6 deoxycarminornycinone 2a (11%) and the epimer 14
(32%), which equilibrates upon addition of trifluoracetic
acid (2a :14 = 8 :l)I3]. The spectroscopic data of racemic
2a (m. p. = 215 -216°C) are consistent with the literature
valuesrpJ.Chromatographically, (_t)-2a behaves like optically active 6-deoxycarmonomycinone (m. p. = 176177"C), which was obtained from naturally occumng 6deoxydaunomycinone 2brZJ
by cleavage of the methyl ether
(~c13)'28'.
Received: July 7, 1983 [ Z 455 IE]
German version: Angew. Chem. 95 (1983) 897
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983. 1267-1282
0 Verlag Chemie GmbH. 6940 Weinheim, 1983
0570-0833/83/1111-0875 S 02.50/0
875
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