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Cyclopentadienone Complexes as Synthons Ring- and Regiospecific Nucleophilic Additions to Cobaltocenium SaltsЧSynthesis of Substituted Cyclopentadienes and Cyclopentenones.

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tetrahydrofuran (THF) into mixtures of 3 and 4 (Table 2).
The observed ring selectivity is clearly suggestive of an
electronic preference to attack the substituted five-membered ring, whereas steric factors force relatively bulky nucleophiles R to add to the unsubstituted ligand. The stereoretention observed in the preparation of 3d4c and 3d/
4d is strongly indicative of a true nucleophilic substitution
mechanism.
The less substituted cobaltocenium salts 5 react with organolithium reagents to give 6-9 (Table 3). The results
show that the additions are governed by a subtle interplay
of steric, charge and orbital control; this is backed up by
extended Huckel calculations.
Cyclopentadienone Complexes as Synthons:
Ring- and Regiospecific Nucleophilic Additions to
Cobaltocenium Salts-Synthesis of
Substituted Cyclopentadienes and Cyclopentenones**
By JeHrey P. Tane and K . Peter C. VollhardP
The recent emergence of a variety of novel cyclopentanoid natural productsr'], particularly those exhibiting physiological activity, has led to a renaissance in synthetic approaches to five-membered ring cornpounds"l. Few have
relied on transition metal mediated or controlled CC bond
formation^",^^. We have reported on the photochemical
[ 2 + 2 + 2) cycloaddition of two alkynes and carbon monoxide to cobalt-complexed cyclopentadienonesr6] and now
describe the exploitation of the metal as a stabilizing and
directing group['].
SiMeQ
2
SiMe?
Table 2. Nucleophilic addition of RLi to 2.
a
b
C
d
e
f
g
h
i
i
k
I-Bu
CHI
n-C6H13-CH=CH (trans)
n-C6H~3-CH=CH (cis)
n-C6H B 3 - W
Me,Si--C--C
CH,O-C=C
t-BuO-C=C
C6H5S-C=C
CI-C*
H
0
29
55
19
73
80
74
69
75
74
75
4
loo
71
45
81
27
20
26
31
25
26
25
Yield
84
98
85
80
95
83
92
94
89
79
100
[*] Prof. Dr. K. P. C. Vollhardt, Dr. J. P. Tane
Department of Chemistry, University of California, Berkeley
Materials and Molecular Research Division,
Lawrence Berkeley Laboratory
Berkeley, California 94720 (USA)
This work was supported by the National Institute of Health (GM
22479). K . P. C. V. is a Camille and Henry Dreyfus Teacher-Scholar
(1978-83).
Angew. Chem. In!. Ed. Engl. 21 (1982) No. 8
R
Yield [Yo]
m
b
c
d
r-Bu
CH,
n-C6H13-CH-CH
Me3Si-CrC
(trans)
59
64
66
68
4
20
21
14
0
0
0
10
37
16
13
8
75
82
89
77
[%I
The neutral q4-2,5-bis(trimethylsilyl)cyclopentadienone(qS-cycIopentadiene)cobalt1 gives 2 on treatment with dimethyl sulfate: 2 is converted by organolithium reagents in
[**I
6 : 7 : 8 : 9
Table 3. Nucleophilic addition of RLi to 5.
The synthetic utility of the method for five-membered
ring compounds is demonstrated by the oxidative demetallation of 3 to furnish the free ligand, or by the application
of
an
oxidation-hydrolysis
sequence
(typically
CuClz . 2 HZO or FeCI3.6 H 2 0 and oxalic acid) to generate
potentially valuable 4-substituted 2-trimethylsilyl-2-cyclopentenones 10-13.
4
3:
9
SiMes
3
R
r(
8
7
6
Me3Si$
R
10, R CH3
11, R = ~ - C ~ H ~ S - C H = C (trans)
H
12, R = n-CeH13-C-C
13, R = H3COCCH2
II
0
Received: April 14, 1982 (Z 10 IE]
German version: Angew. Chem. 94 (1982) 642
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982. 1360- 1372
[I] See the references in B. M. Trost, T. A. Runge, J . Am. Chem. Sac. 103
(1981) 7559.
[2] R. A. Ellison, Synthesis 1973, 397.
I51 A. Bou, M. A. Pericas, F. Serratosa, Terrahedron Lett. 23 (1982) 361; N.
E. Shore, M. C. Croudace, J. Org. Chem. 46 (1981) 5436; R. F. Newton,
P. L. Pauson, R. G. Taylor, J. Chem. Res. (S) 1980. 277; (M)1980. 3501;
A. J. Pearson, M. Chandler, Terrahedron Left. 21 (1980) 3933; T. Hudlicky, F. J. Koszyk, T. M. Kutchan, J. P. Sheth, J. Org. Chem. 45 (1980)
5020; R. C. Larock, K. Oertle, G. F. Potter, J. Am. Chem. Sac. 102 (1980)
190; B. M. Trost, D. M. T. Chan, ibid. 101 (1979) 6429; Y. Ito, H. Aoyama, T. Hirao, A. Mochizuki, T. Saegusa, ibid. 101 (1979) 494; R. Grigg, T.
R. B. Mitchell, A. Ramasubbu, J. Chem. Sac. Chem. Commun. 1979, 669;
J. L. Roustan, J. Y. Merour, C. Charrier, J. Benaim, P. Cadiot, J . Orga-
0 Verlag Chemie GmbH, 6940 Weinheim. 1982
0570-0833/82/0808-0617 $ 02.50/0
617
nomef. Chem. 168 (1979) 61; H. Schmid, P. Naab, K. Hayakawa, Helv.
Chim. Acta 61 (1978) 1427; Y. Hayakawa, K. Yokoyama, R. Noyori, J .
Am. Chem. SOC.lOO(1978) 1799: W. Best, B. Fell, G. Schmitt, Chem. Ber.
109 (1976) 2914; E. Weissberger, P. Laszlo, Ace. Chem. Res. 9 (1976)
209.
[61 E. R. F. Gesing, J. P. Tane, K. P. C. Vollhardt, Angew. Chem. 92 (1980)
1057; Angew. Chem. Int. Ed. Engl. 19 (1980) 1023.
[7] J. E. Sheats, J. Organomer. Chem. Libr. 7 (1979) 461.
0
0
0
Y Y
A0A0
0
o+o
4
Synthesis and Valence Isomerization of
2,7-Dihydro-2,2,7,7-tetramethylpyrene**
By Jean Ackermann, Herbert Angliker, Erich Hasler, and
Jakob Wirz*
The potential to study the photochemical and thermal
valence isomerization shown in Scheme 1 has been our
prime incentive to synthesize the cross-conjugated polyene
2,7-dihydropyrene. We chose the blocked and sterically
shielded 2,2,7,7-tetramethyl derivative 1 as a model compound to protect the system against polymerization, tautomerization, disproportionation, and oxidation. Due to
geometrical constraints, ring opening of a cyclopropane
fused to the peri-positions of naphthalene can proceed
only in a disrotatory manner; the valence isomerizations
1 + syn-2 and 1 + anti-2 can therefore be classified as intramolecular [,6, ,6,] and [,6, ,6J cycloadditions/cycloreversions, respectively. They are thus “forbidden” in
the sense of the Woodward-Hoffmann rules and are likely
to proceed via a reactive diradical intermediate 3I3]
(Scheme 1).
+
@
c
+
@
-$:
x+x
6 , X = OH, B r
Scheme 2.
isomers syn-2 and anti-2 ( 5 : 1 : 1) are formed, which are
readily separated by chromatography. The photoreaction
is reversible upon short wavelength irradiation (A =313
nm), but the photostationary equilibrium is strongly temperature dependent, favoring 2 at room temperature and 1
at 77 K. The thermal equilibrium lies entirely on the side
of 1 in agreement with the predictions of thermochemical
additivity rules (calculated heats of formation:
ArH(1) = 246, ArH(2)= 295 kJ/mol). However, the equilibrium between the two stereochemical isomers syn-2 and
anti-2 proceeds at a rate which is at least two orders of
magnitude faster than that of the rearrangement 2+ 1 (ca.
s-’ at 100 “C). We conclude that the recyclization of
the diradical (3- 2 ) requires a significantly lower activation energy than the cleavage of the second ring ( 3 + l ) although the second reaction leads to the more stable product. Clearly, the cycloreversion 2- 1 is not a concerted
process, since it requires a higher activation energy than
the cleavage of only one bond to form 3.
Received: March 26, 1982 (2 156 IE]
German version: Angew. Chem. 94 (1982) 632
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982, 1429-1439
‘ \’
3
1
CAS Registry numbers:
1,82294-27-7; syn-2,82294-28-8; anti-2, 82336-39-8; 4,81-30-1; 5 , 82294-299; 6 (R=Br), 82294-30-2; 6 (R=OH), 82294-31-3: 7, 82294-32-4.
Scheme 1.
The preparation of 1 was achieved in a five-step synthesis starting from 1,8 :4,5-naphthalenetetracarboxylicacid
dianhydride 4 (Scheme 2). 1 is isolable as a yellow, crystalline solid (decomp. 180 “C) and is stable in solution in
the presence of air if light is rigorously excluded. The
NMR chemical shifts of the vinyl H atoms substantiate the
expected polyene character of 1 and provide no evidence
for the presence of an “aromatic” ring current in the central naphthalene moiety. 1,2,3,6,7,8-Hexahydro-2,2,7,7-tetramethylpyrene is obtained in quantitative yield upon hydrogenation of 1 in presence of PtOz in isooctane.
Solutions of 1 are rapidly bleached in diffuse daylight
or upon irradiation at A=405 nm, whereby the valence
[*I Priv.-Doz. Dr. J. Win, E. Hasler, Dr. H. Angliker, J. Ackermann
[**I
Physikalisch-Chemisches Institut der Universitat
Klingelbergstrasse 80, CH-4056 Basel (Switzerland)
This work was supported by the Swiss National Science Foundation.
618
0 Verlag Chemie GmbH. 6940 Weinheim, 1982
[3] M. Gisin, E. Rommel, J. Win, M. N. Burnett, R. M. Pagni, J . Am. Chem.
Soc. 101 (1979) 2216; M. S. Platz, ibid. I01 (1979) 3398, and references
cited therein.
Fourfold Bridging of the Benzene Ring
in One Step“]**
By Brigitte Klieser and Fritz Vogtle*
Until now, two benzene rings could be linked by more
than three bridges only via multistage indirect route^'^^^,'^.
We have now found that the fourfold intermolecular coupling of ortho-positions can be accomplished in a single
step using the “cesium effect”‘’’.
[*I Prof. Dr. F. Vogtle, B. Klieser
Institut fur Organische Chemie und Biochemie der Universitat
Gerhard-Domagk-Strasse 1, D-5300 Bonn 1 (Germany)
I**] This work was supported by the Fonds der Chemischen Industrie.
0570-0833/82/0808-0618 $! 02.50/0
Angew. Chem. Int. Ed. Engl. 21 (1982) No. 8
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synthons, cyclopentenones, regiospecific, additional, ring, saltsчsynthesis, complexes, substituted, cyclopentadienyl, cobaltocenium, nucleophilic
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