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Bicyclo[4.4.2]dodeca-1-eneЦ The First УHyperstableФ Bridgehead Olefin

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Received: May 29, 1980 [Z 53 IE]
German version: Angew. Chem. 94 (1982) 312
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982. 654-659
[I] F. Gerson, H. Ohya-Nishiguchi, C. Wylder, Angew. Chem. 88 (1976)
617: Angew. Chem. Inr. Ed. Engl. I5 (1976) 552.
[Z] F. Gerson, W. B. Martin, Jr., J. Am. Chem. SOC.91 (1969) 1883.
[6] T. Sato, K. Torizuka, M. Shimizu, Y. Kurihara, N. Yoda, Bull. Chem.
SOC.Jpn. 52 (1979) 2420.
[lo] H. J. Reich, D. J. Cram, J. Am. Chem. Sot. 90 (1968) 1365.
Bicyclo[4.4.2ldodeca-l-eneThe First "Hyperstable" Bridgehead Olefin**
By Hanspeter Kukuk, Ehrhardt Proksch. and
Armin de Meijere*
Bridgehead olefins have long lost their uniqueness"'. O n
the basis of force field calculations the possible existence
of "hyperstable" bridgehead olefins has recently been predicted, yet no experimental evidence of such species has so
far appeared in the literature[']. We therefore describe the
surprising result of unsuccessful attempts to prepare a
bridged trishomocycloheptatrienyl cation, which unexpectedly led to the formation of the hyperstable compound
7 (Scheme 1).
Catalytic hydrogenation of the exo,exo-bishomobullvalene 1 13] afforded pentacyclo[4.4.2.02~4.05~7.08~~o]dodecane
2,
an ethano-bridged cis-trishomocycloheptatriene. 2 can be
oxidized to the bridgehead alcohol 3 (42% yield) by dry
o z ~ n a t i o n [on
~ l silica gel deactivated with 5 wt-% of potassium hydroxide. Reaction of 3 with sulfinyl chloride in the
presence of diethylaminomethylpolystyrene does not lead
2
1
4
3
5
7
6
8
Scheme I . [a] R 0 2 / H Z , MeOH, RT; [b] 03/SiOZ-KOH; [c] SOC12, polymer
base, CH2Clz, -40°C to RT: [d] SbF3, SOZCIF, - 110 to -78°C; [el PtOJ
H2, Et20, 24 h; [fl as [el, but 72 h.
to the expected bridgehead chloride 4, even under mild
conditions (-40 to +2O"C). Rather, according to its 'Hand I3C-NMR spectra the product (61%) is the 10exo-chlorobicyclo[4.4.2]dodeca-1,4,7-triene6 [S('H) = 5.82 (dddd,
H-5), 5.52-5.65 (m, H-2,4,7), 5.12 (dddd, H-8), 4.37 (ddd,
H-10""'"); S(I3C)= 140.5 (C-I), 5 doublets at 138.1, 131.7,
130.8, 128.8, 117.9 (C-2,4,5,7,8)].
[*] Prof. Dr. A. de Meijere, H. Kukuk, Dr. E. Proksch
[**I
lnstitut fur Organische Chemie und Biochemie der Universitat
Martin-Luther-King-Platz 6, D-2000 Hamburg 13 (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and BASF AG, Ludwigshafen.
306
D Verlag Chemie GmbH. 6940 Weinheim, 1982
Obviously 4 is so labile that it rearranges in a
[,2, ,2, ,2,]-cycloreversion via the bridgehead cation to
6, even in the weakly polar solvent dichloromethane. Several attempts by spectroscopic investigation to directly demonstrate the presumed intermediary formation of the
bridged trishomocycloheptatrienyl cation 5 as the first representative of its kind[51have failed. Under superacidic
conditions (HS03F/SbF, or SbF,/SO,CIF) only polymers
were obtained, both from 3 as well as from 6.
6 is a bridgehead olefin of the hitherto little known bicyclo[4.4.2]dodecane system. Such bridgehead olefins
should, according to molecular mechanics calculations, exhibit less strain energy than the corresponding saturated
hydrocarbons[21.6 can be reductively dehalogenated over
prehydrogenated platinum dioxide in ether, and selectively
hydrogenated to the monoolefin 7 [6(' H ) = 5.35 (br. dd, H2 ) ; S(l3C)= 142.26 (s, C-I), 126.95 (d, C-2), 10 signals between 36.84 and 24.351. The finding that further hydrogenation to bicyclo[4.4.2]dodecane 8 requires at least three
times longer reaction time, seems to indicate that there is a
"hyperstability effect"[*] in 7.
+ +
Received: November 19, 1981 [Z 56 IE]
German version: Angew. Chem. 94 (1982) 304
The complete manuscript of this communicatlon appears in:
Angew Chem. Suppl. 1982. 696-701
[ I ] Cf. G. Kobrich, Angew. Chem. 85 (1973) 494: Angew. Chem. I n t . Ed. Engl.
12 (1973) 464; R. Keese, ibid. 8 7 (1975) 568 and 14 (1975) 528, and references cited therein.
[2] W. F. Maier, P. yon R. Schleyer, J. Am. Chem. Soc. 103 (1981) 1891.
[3] A. de Meijere, C. Weitemeyer, 0. Schallner, Chem. Eer. I10 (1977)
1504.
141 E. Proksch, A. d e Meijere, Atrgew. Chem. 88 (1976) 802: Angew. Chem.
In,. Ed. Engl. 15 (1976) 761, and references cited therein.
151 Cf. K. Ohkata, L. A. Paquette, J . Am. Chem. SOC.102 (1980) 1082; L. A.
Paquette, P. B. Lavrik, R. H. Summerville, J. Org. Chem. 42 (1977) 2659,
and references cited therein.
Synthesis of Bicyclo[3.3.l]nonane Derivatives
under Physiological Conditions
By Steven H . Bertz* and Gary Dabbagh
Prelog et al. prepared a variety of phenols from 1,3-dicarbonyl compounds and diethyl 3-oxoglutarate or ethyl
acetoacetate in hot ethanolic sodium ethoxideI'"]. It has
been shown that in some cases better yields can be obtained by conducting the reaction at room temperature in
aqueous solution containing 0.1 to 1 equivalents of NaOH
(pH 7- 8) and methanol cosolvent[Ib1. Organic chemists
often refer to such buffered"'] aqueous solutions as "physiological conditions"['d1. We wish to report that when they
are treated with dimethyl 3-oxoglutarate 1 under these
OHCyCHO
E
E
R
I
R
4
5
2,R=H
3, R = I I - C ~ H ~ ~
E = CO,CH,
6
7
[*I Dr. S . H. Bertz, G. Dabbagh
Bell Laboratories
600 Mountain Avenue, Murray Hill, New Jersey 07974 (USA)
0570-0833/82./0404-0306 S 02.50/0
Angew. Chem. Inl. Ed. Engl. 21 (1982) No. 4
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