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Donor-Acceptor-Stabilized 1 6-Methano[10]annulene Derivatives.

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141 For the synthesis of 1,4-benzodioxins cf. E. Schrnidf. Diplomarbeit, University of Wiirrburg 1981.
151 W. Adam, H. J . Eggelte, J. Org. Chem. 42, 3987 (1977).
(n[6] ( I f f ) . 41% yield, yellow crystalline solid, m.p.=70-72"C
CSHIL/CHICL), >98% peroxide content by iodometric titration, satisfactory elemental analysis; 'H-NMR (CCI,, TMS): 6=6.33 (I H, s,
4 - H ) , 7.16 (4H, s, arom. protons), 7.45-7.61 and 7.83-7.97 (5H, m,
phenyl); IR (CCI,): v=3080,2960, 1620, 1500, 1470, 1460 cm-'.
171 (Sa). 82% yield, b.p.= 110°C/0.15 torr, n$= 1.5701; satisfactory elemental analysis; 'H-NMR (CCI,, TMS): 6=7.00--7.50 and 7.90-8.09
(SH, m, phenyl), 7.12 (4H, s, arom. protons), 7.95 ( I H, s, H-C02); IR
(CCI,): v=3080 (aromatic CH), 1750 ( C 4 ) cm-'.
IS] (Ib). 35% yield, yellow crystalline solid, m.p.=72-76"C
(nC S H I ~ K H ~ C >98%
I ~ ) , peroxide content by iodometric titration, satisfactory elemental analysis: 'H-NMR (CCI4, TMS): 6= 1.41 (3H, s,
CH,), 7.06 (4H, s, arom. protons), 7.40-7.57 and 7.73-7.88 ( 5 H, m,
phenyl); IR (CCI,): 3080, 2950, 1615, 1495, 1455, 1395 cm-'.
191 (lc), 33% yield, yellow crystalline solid, m. p. = 1 18 - 122 "C (dec.) (nC5HI2/CH2CI2),satisfactory elemental analysis; 'H-NMR (CCI,, TMS):
6= 1.81 (6H, s, CHJ and 6.99 (4H, s, arom. protons); IR (CCI,): 3040,
3000, 1612, 1495, and 1264 cm-'.
[lo] (Sb), 83% yield, b.p. = 15OoC/0.IO torr, RE'= 1.5631, satisfactory elemental analysis; 'H-NMR (CCI,, TMS): 6=2.15 (3H, s, CH,), 7.45 (4H, s,
arom. protons), 7.65-7.87 and 8.30-8.35 (SH, m, phenyl); IR (CCI,):
3080, 2960, 1775, 1755 cm-'.
[ I I ] (5c) formed quantitatively and IR and 'H-NMR identical with literature
data, H. Nimr. K. Das. N. M. Minernura. Chem. Ber. 104, 1871 (1971).
quinoid partial structure is not derived from a benzoid aromatic system.
The synthetic route to (2a) starting from the tautomerid
valence isomeric mixture (-?)I3] is outlined in Scheme I.
x@
(2c)
Scheme 1. A : 5-methyl-1.3-benzodithiolylium perchlorate 141, anhydrous
CH,CN, N2, 20"C, 12 h; B: NEt,, CH2C12,20°C; C: Reaction to give (5) or
(6): dicyanoketene [5] or 9-carbonylfluorene [6], anhydrous toluene, N2, 1.5 2 h.
Donor-Acceptor-Stabilized
1,6-MethanoflOlannulene Derivatives'"'
By Richard Neidlein and Hartmut Zeiner"'
Dedicated to Professor Rolf Huisgen on the occasion of
his 60th birthday
The diketo derivative (la) of 1,6-methano[IO]annulene, a
homologue of 1,4-naphthoquinone, cannot be synthesized"] since it is thermodynamically less stable than its
valence isomer (lb).
The bicyclic cycloheptatriene structure of (2a) is based
on spectroscopic evidence: in the 'H-NMR spectrum, the
CH,-bridge protons form an AX system with geminal coupling 2JAx=10.7 Hz; in contrast, 4-5 Hz would be expected for a tricyclic norcaradiene structure such as in
(2b)[71.
A further index for (2a) is provided by the absorption of H-7 to H-10[81(ABCD system at relatively low field
strengthL6.7). The "push-pull" effect in (24 produces a
carbonyl absorption at conspicuously low wavenumber, as
well as a relatively high basicity; the negative solvatochromism of the longest wavelength UV bands indicates a
marked contribution of the polar mesomeric structure (2a')
to the ground state.
Conversion of the basic (2a) into the conjugated red-violet acid (2c) (Scheme 1) shifts the absorption of the CH2bridge protons (AB signal) 1.18 ppm upfield. With
Table 1. Selected physical data for compounds (2a). (5). and (6).
In contrast, however, the bicyclic quinoid structure is
considerably more stable than the tricyclic structure if it is
incorporated into an integral part of a ''push-pull'' system
as in (2a). No evidence that the valence isomer (2b) exists
has been obtained to datei2].To the best of our knowledge,
(2a) is the first "push-pull"-stabilized quinomethide whose
['I Prof. Dr.
["I
R. Neidlein, Dr. H. Zeiner
Pharmazeutisch-chemisches lnstitut der Universitat
Im Neuenheimer Feld 364, D-6900 Heidelberg (Germany)
This work was supported by the Fonds der Chemischen Industrie and
by the Deutsche Forschungsgemeinschaft.
1032
8 Verlag Chernie GmbH. 6940 Weinheirn, 1981
(20): M.p.=70-71°C:
yield 82%; M f=322.0485 (calc. 322.0484); 'HNMR (90 MHz, CDCI3, TMS): 6=0.65 (d, AX signal, %,= 10.7 Hz, I H,
CH,), 3.29 (d, AX-signal, 'JAx= 10.7 Hz, 1 H, CH,), 2.37 (s, CH,), 5.85 (d, AB
signal, 3J3.4=11.8 Hz, H-41, 7.29 (d, AB-signal, '.I3,= 11.8 Hz, H-3). 6.867.34 (m, H-7 to H-I0 and 3 arom. H) 181; UV (CH,CN): d,,,=244 nm
(E= 10094). 316 (3154, sh), 445 (8306); UV (CH2CI2): d.,,,=245
(11 478, sh),
254 (10655, sh), 295 (4364, sh), 316 (3540, sh), 458 (9253); IR (KBr): 1610
cm-'(CO), 1535 ( C 4 ) ; MS (100 eV, 170°C): rn/r 322 (IWh, M')
(2c)G(2a) in CFKOOD: 'H-NMR (90 MHz, TMS): 6=0.21 (d, AB-signal,
'JAB=10.8 Hz, 1 H, CH,), 1.37 (d, AB-signal, 2JAB=
10.8 Hz, I H, CH,), 2.63
(s, CH,), 6.63 (6,,, ,J3.4= 10.2 Hz, H-4), 7.34-8.19 (m,H-3, H-7 to H-I0 and
3 arom. H)
(5): yield 52%; M + =370.0597 (calc. 370.0597); 'H-NMR (90 MHz, CD,C12,
TMS): 6=0.80 (d, AX signal, ,JAx=10.9 Hz, 1 H, CH,), 2.75 (d, AX signal,
'JAx=10.9Hz, 1H,CHz),2.39(s,CH,),6.49(d,ABsignal,'J,.4=11.1 Hz,H4), 6.98 (d, AB signal, 'Ju= 11.1 Hz, H-3), 7.05-7.46 (m,H-7 to H-10 and 3
arom. H)
(6): M.p.= 128°C;yield46%; 'H-NMR(90 MHz,CDC13,TMS):6=0.89(d,
AX system, ' J A X = 10.6 Hz, I H, CH2), 3.22 (d, AX signal, 2JAx= 10.6 Hz, I H,
'J3..,= 11.6 Hz, H-4). 6.86-7.86 (m, H-3, H-7
CH2), 2.32 (s, C H A 6.50
to H-10 and I I arom. H): UV (CH3CN): d,.,=204
nm (&=74976), 230
(72179). 252 (43083). 264 (34131, sh), 318 (3917, sh), 340 (3357, sh), 522
(16226); UV (CH2C12):d2,:,,=305 nm (~=13885,sh), 322 (7295, sh), 342
(5648, sh), 540 (17415); MS (100 eV, 250°C): rn/r 470 (62%, M ' )
0570-0833/81/1212-1032 $ 02.50/0
Angew. Chem. Inl. Ed. Engl. 20 (t98t) No. 12
6,,,= 0.79 (CF3COOD) they lie close to the characteristic
high-field region of disubstituted 1,6-methano[l01annulenes (S= - 0.5 to 0.5). Furthermore, aromatization of
the C,, bicycle in (2c) is also indicated by the paramagnetic
shift of the low-field multiplet by 0.67 ppm, as well as the
reduction of 353.4by ca. 1.6 Hz, suggesting a decrease of
the bond order between C-3 and C-4.
Similar results are obtained with the ''push-pull'' stabilized quinodimethanes (5) and (6). which are readily accessible from (2a) (Scheme 1); however, only (6) can be protonated at the exocyclic double bond (CS-Cl').
+
Received: June 3, 1980,
in altered form: July 8, 1981 [Z 927 IE]
German version: Angew. Chem. 93. I117 (1981)
CAS-Registry numbers:
(20). 79839-35-3; /2c). 79855-11-1; (3) isomer I, 10474-50-7; (3) isomer 11,
79839-36-4; (5). 79855- 12-2; (6). 10474-55-2; 5-methyl- 1,3-benzodithiolylium
perchlorate, 72939-27-6; dicyancarbene, 4361-47- I ; 9-carbonylfluorene. 48625-9.
111 E. Vogel, E. Lohrnar, W. A. Boll, B. Sohngen, K. Miillen, H . Giinther, Angew. Chem. 83, 401 (1971); Angew. Chem. Int. Ed. Engl. 10. 397 (1971).
121 Temperature-dependent 'H-, and above all, "C-NMR measurements are
planned.
131 E. Vogel. W. Schrock. W. A. Boll, Angew. Chem. 78, 753 (1966); Angew.
Chem. Int. Ed. Engl. 5, 732 (1966).
141 L. Soder. R. Wizinger, Helv. Chim. Acta 42, 1733 (1959).
151 R. Neidlein. E. Bernhard, Angew. Chem. 90, 395 (1978); Angew. Chem.
Int. Ed. Engl. 17. 369 (1978).
161 H. Staudinger. Ber. Dtsch. Chem. Ges. 39. 3062 (1906).
[7] D. J. Patel. M . E . H . Howden. J . D. Roberts, J. Am. Chem. SOC.85. 3218
(1963).
I81 H-7 to H-I0 absorb, together with the benzoid aromatic protons, in a
complex non-analyzable multiplet.
Potassium Metal Dispersed on Silica:
A Versatile Reagent in Organic Chemistry'**'
By Jaacov Levy, Dov Tamarkin, Henry Selig, and
Mordecai Rabinovitz"'
In recent years there has been much interest in reagents
supported on silica
on graphiter3', and on alumina[,]. We report here the preparation and some reactions of
a new reagent in this class-potassium metal dispersed on
silica gel.
Silica gel (1.500 g, BDH, 70-100 mesh, dried for 3
weeks at 100-120°C) was heated to 170°C and stirred
under argon with metallic potassium (0.780 g, 0.02 mol,
BDH, washed with petroleum ether, and I-butanol in petroleum ether) for 20 min, and cooled to room temperature. A gray free flowing, relatively air stable powder (1)
was obtained. X-ray powder diffraction studies show the
material to be amorphous. Quenching (1) with water released hydrogen gas from whose volume it was determined
that 85-9Oo/o of the potassium is in elemental form.
Several investigations were carried out in order to study
the reactivity of (1). Addition of benzophenone (1.82 g,
0.01 mol) in petroleum ether to (I), prepared as above from
0.02 rnol potassium under argon at room temperature, produced a strong blue coloration after 5 min. After 8 h at
room temperature the mixture was quenched with water:
(1'
Prof. Dr. M. Rabinovitz, J. Levy, D. Tamarkin, H. Selig
Department of Organic Chemistry
and DeDartment of Inoraanic and Analvtical Chemistrv
The Hebrew University of Jerusalem
Jerusalem 91 904 (Israel)
-
["I
This work was supported by the Israel Commission for Basic Research.
Angew. Chem. I n t . Ed. Engl. 20 (1981) No. 12
isolation of the organic products afforded benzopinacol
(1,1,2,2-tetraphenyl-1,2-ethanediol) (m. p. 179- 18O"C,
72% yield, 1.3176 g, 0.0036 rnol); and benzhydrol (m.p.
65-68"C, 8% yield, 0.1450 g, 0.0008 mol). In contrast, no
reaction was observed at room temperature with potassium
metal; when heated to reflux a reaction took place which
yielded a 1 : 1 mixture of benzopinacol and benzophenone
in 60-80% total yield.
(I), prepared from 0.02 rnol potassium was reacted with
bromobenzene (1.490 g, 0.0095 mol) in diethyl ether and
petroleum ether to afford biphenyl (m. p. 65 "C, 82% yield,
0.603 g, 0.00389 rnol); no polyphenylenes were observed.
Similarly, iodobenzene afforded 8 I% biphenyl. The Fittig
reaction of aryl halides with metallic potassium takes place
at higher temperatures, and yields only 20-30% biaryIs['l.
These examples show that the dispersion of potassium
on silica ( I ) has greater reactivity and different selectivity
than metallic potassium. The tendency of (1) to facilitate
formation of "dimers" (benzopinacol, biphenyl) as exemplified by its reactions with benzophenone, bromobenzene
and iodobenzene, may originate from the proximity of two
reaction centers on the surface of the silica; on average
4.5-S active sites per 100 A' are found'"].
Received: May 29, 1981 [Z 926 IE]
German version: Angew. Chem. 93. 1123 (1981)
CAS-Registry numbers:
Silica, 7631-86-9; potassium, 7440-09-7; benzophenone, 119-61-9; benzopinacol, 464-72-2; benzhydrol, 91-01-0; bromobenzene, 108-86-1; iodobenzene,
591-50-4; biphenyl, 92-52-4.
[I] For general review: A. McKillop, D. W. Young, Synthesis 1979. 401.
121 K . M . Gitis, V . N. Meduedeu. 0.D. Sterlisou, M . 1. Rozensart. V. 1. Barisbnikoua, Izv. Akad. Nauk SSSR, ser. Khim. 1976, 570. K . G. Allum, R.
D. Hancock, I . V . Howell, T. E. Lester, S. McKenzie. R. C. Pitkethly. P. J .
Robinson, J. Catal. 43. 331 (1976); K . J. A. Clarke, L. Manninger. T.
Baird. ibid. 54. 230 (1978); J . T. Richardson. R. J. Dubus. ibid. 54, 207
(1978); B. N. Kusnetsou, I . A. Ougyannikoua, Y. A. Ryndin. S. B. Erenburg, A. B. Gil'uar, Y. I . Emtakou. Kinet. Katal. 19. 749 (1978).
131 H. Selig. M . Rabinouitz, I . Agranat. C. H . Lin. L. Ebert, J. Am. Chem.
SOC.98, 1601 (1976); M. Rabinouitz. I. Agranat, H. Selig, C. H . Lin. L.
Ebert, J. Chem. Res. (S) 1977. 216, ( M ) 1977. 2353; I . Agranat, M . Rabinouitz, M. Selig. C. H. Lin. Chem. Lett. 1975, 1271; H . Selig. L. Ebert.
Adv. Inorg. Radiochem. 23, 281 (1980).
[4] E. Czaran. J. Finster, K . H . Schnabel, Z . Anorg. Allg. Chem. 443. 175
(1978); J. Rebek. R. McCready, Tetrahedron Lett. 1979. 4437.
[S] 0. Blurn-Bergrnann, J. Am. Chem. SOC.60, 1999 (1938).
161 M . Zarnora, J. Chem. Phys. 82, 588 (1978).
[ F ~ ~ s ( s ~ c , ~ H ~ ~:The
) ~ ] *First
- Synthetic
~
~Iron-sulfur
i Cluster~Compound
~
~
BY Gerald Henkel, Wolfgang Tremel, and Bernt Krebs"]
Preliminary results of an X-ray structure analysis by
Stout et al.['I as well as Mossbauer spectroscopic investigations by Emptage et al.[*Ion a ferredoxin-like iron-sulfur
protein ("iron-sulfur protein 111") from A. vinelandii. first
described by Shethnd3] and Yoch and ArnonL4]about 10
years ago, would suggest that the center with the low redox
potential of - 420 mV represents a novel type of trinuclear
cluster.
Stout et al."] interpret this cluster as a 3Fe-3S center,
whose structure can be derived from the dimeric Fe2S2unit
of the 2Fe-2S ferredoxins by insertion of a distorted planar FeS, group.
I*] Prof. Dr. B. Krebs, Dr. G. Henkel, DipLChem. W.Tremel
Anorganisch-chemisches lnstitut der Universitilt
Gievenbecker Weg 9, D-4400 Miinster (Germany)
0 Verlag Chemie GrnbH. 6940 Weinheim, 1981
0570-0833/81/1212-1033 S 02.SO/O
1033
l
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stabilizer, annulene, acceptor, donor, derivatives, methane
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