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Degenerate Butadienylcyclopropane Rearrangement in Tricyclo[5.3.0

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10,l I-Dihydrocyclobuta[b]triphenylene and 1,2,5,6,9,1O-Hexahydrotriscyclobuta[ b,k,nltriphenylene[**I
By R. L. Funk and K . P. C. Vo/lhardf[*l
The synthesis and properties of various aromatic carbocycles
fused to one strained ring have been the subject of considerable
recent research activity. There are considerably fewer structures known consisting of two strained rings fused to an
aromatic system. We now wish to report the synthesis of
1,2,5,6,9,10-hexahydrotriscyclobuta[b,h,n]triphenylene ( I ) , a
benzenoid tetracycle to which three strained rings are symmetrically fused"].
For comparison model (41 with one annelated cyclobutane
ring (10,l I-dihydrocyclobuta[b]triphenylene) was prepared
by the iodine catalyzed oxidative photocyclization[31of 43diphenyl- 1,2-dihydro~yclobutabenzene[~~
followed by preparative thin layer chromatography (yield 82 38 conversion;
m.p. 168-169°C). The structure assignment is based on the
physical and chemical properties. Hydrogenation (Pt)leads
to the phenanthrene derivative (5)l2] [m. p. 151-1 52"CI.
(x, 'x
(4)
(51
The increasing strain in the series triphenylene, ( 4 ) and
( 1 ) is reflected in the physical and chemical properties of
131
Treatment of a concentrated (1.2 M) solution of 4-bromo-5iodo-l,2-dihydrocyclobutabenzenewith magnesium (room
temperature; 12h) leads to a complex mixture of halogenated
coupled products, in addition to the biphenylene derivative
(3) and the desired triphenylene derivative (Z)[*]. The new
cyclobutaarene ( I ) was obtained after repeated preparative
thin layer chromatography on silica (3% ether in pentane)
and fractional crystallization from ether as colorless plates
(yield 0.5 'x)which decomposed above 260°C without melting.
The structural assignment is based on the spectral and chemical
properties [MS: m/e=306.1406 (calcd. 306.1408), M'; 'HNMR (CDCI,): T = 1.70 (s), 6.57 (s); electronic spectrum: Fig.
11. Hydrogenation with Pt (in ethanol) proceeds unusually rapidly to the partially hydrogenated benzene derivative (2)[2,61,
a colorless oil ['H-NMR (CCI,): r=6.6-8.3 (m); UV (ether):
h,,,,= 227 sh, 238 sh, 2701.
these compounds. Thus, fusing one cyclobutane ring to triphenylene seems to lead to increased bond localization in
one benzene ring as indicated in structure ( 4 ) . This is evidenced
by the chemical shift for 4-H, 5-H (T= 1.32), intermediate
between the corresponding absorptions in the phenanthrene
derivative ( 5 ) (T = 1.25)and triphenylene (T = 1.44)15.']the
, relatively high chemical shift for 9-H, 12-H ( T = 1.60) and the ease
of hydrogenation of / 4 ) [ h 1Fusion
.
of three cyclobutane rings
seems to result in increased bond fixation as suggested in
formula (Z). The aromatic signals are shifted an additional
0.1 ppm to higher field due to the cumulative influence of
three four-membered rings['], and hydrogenation is rapidIhl
but leaves the central benzene ring intact. This is, of course,
in striking contrast to the stringent conditions required to
hydrogenate triphenyIeneI"! Finally, the electronic spectra
(Fig. 1 ) exhibit strong bathochromic shifts along this series.
Received: October 30. 1975 [ Z 344 IE]
German version: Angew. Chem XH. 61 (1976)
CAS Registry numbers
( 1 ) . 57674.78-9: (21. 57674-79.0: / . < J . 57674-xn-z:
141. S7674-81-3:
___
( 5 ) . 57674-82-5
A dodecafluorohexahydrotriscyclobuta[~.c,i~]benzenehas been claimed,
but no structural proof was provided: M. 0.Rile!. and J . 0. P a d .
Tetrahedron Lett. IY71, 2871.
[2] All new compounds gave satisfactory analytical andior spectral data.
[3] F. B. ,!4rr//ori., C. S. Wood, and J. 7: GorrloJf. J. Am. Chem. Soc. N6,
[I]
3094 (1964).
K . P. C . Vo//hard~and R. G. Bergrimn, J. Am. Chem. Soc. YO. 4996
( 1974).
[ 5 ] R. If. ,Murfiii, N . Orfur. and F. Giwfs-Eirrrr.il, Tetrahedron 20. 1091
11964).
[6] As shown by competition studies 4.5-diphenyl-1.2-dihydrocyclobutaben[4]
zene is not hydrogenated under these conditions.
[7] The degree of bond fixation may be larger than indicated by N M R
[S]
[Y]
:i
2
220
260
I
I
300
A. [ n m l -
3LO
Fig. 1. Electronic spectra of triphenylene (---J,
in YS":, ethanol.
I
\\
1
chemical shifts since hybridization [8] and ring current effects ( c . g .
relative size of the ring currents of triphenylene. phenanthrene, benzene)
may induce opposing trends.
See Y. q. A . Srruirwirsru. G. R. Zieqlcr, P. C . Moiwrr. A . Lc'wi,. and
R. G. Loidrr, J. Am. Chem. Soc. YO, 1357 11968).
S. FrfrdJmJI. s. Mi,I/iri, A. swdi, and 1. We!fi/i,r. I. Org. Chem. 24,
1287 (1959): J. J. W h l . W R. K i r n r r . and N C . Hoii,uri/, J. Am. Chcni.
and 1. M'iwdiv. J.
SOC.67. 246 (1945): S. Friediififu, M . L. Ki/iffffIu~i.
Org. Chem. 36, 694 (1971).
,
380
( 4 ) (.-....) . and ( I ) (- - - I
[*] R L Funk and Professor Dr K . P. C . Vollhardt
Departmem or Chemistry, University or California
Degenerate Butadienylcyclopropane Rearrangement in
Tricyclo[5.3.0.02~O]deca-3,5-diene
By Klaus Heger and Wolfram Grimme[']
We were recently able to show that above 110-C bicyclo[5.1 .0]octa-2,4-diene ( 1 ) undergoes degenerate butadienyl-
Berkeley. California 94720 (USA)
[**I This work rcas supported by thc Petroleum Research Fund, administered
[*] Dipl.-Chem. K. Heger and Dr. W. Grimme
by the American Chemic;il Society. the Research Corporation and the Energy
Institut fur Orpanische Chemie der L'niversitat
Reseal-ch and Development Administratioti.
5 Kiiln 41. Greinstrasse 4 (Germany)
53
cyclopropane rearrangement; of the two quantum mechanically "allowed" transition states having cisoid or transoid
conformation only the latter is involved[']. However, the tricarbonyliron complex (2) having a fixed cisoid conformation
formally undergoes the same rearrangement already at 90°Crz'.
The metal apparently lowers the activation barrier for the
geometrically less favorable process.
We here report the butadienylcyclopropane rearrangement
in tricycl0[5.3.0.0~~
1°]deca-3,5-diene / 3 a ) whose cisoid geometry is fixed by the ethano bridge; no metal is involved
in this rearrangement. O n treatment with thionyl chloride
and tri-n-butylamine in ether, tricycl0[5.3.0.O~~'~]deca-3,5dien-9-01 (3b)'31 affords the chloride (3c), which is reduced
directly by lithium tetrahydridoaluminate in boiling tetrahydrofuran without further purification. Gas chromatography of
the resulting hydrocarbon mixture (3 m, 20
Reoplex on
kieselguhr, 45ml He/min, 120°C) affords ( 3 a ) [17% based
on (3b), retention time 7min; NMR (CDC13, TMS internal):
~ = 3 . 8(m) (2 olefinic H), 4.2 (m) (2 olefinic H), 6.9 (m) (7-H),
7.7-9.0 (m) (7 aliphatic H ) ; UV (dioxane): hm,,=267nm
( E =4200)] alongside the tetrahydroazulenes ( 4 ), ( 5 ) , and (6),
probably formed by rearrangement of the chloride (3c).
R2 R'
R' = H , K~ = H
(3b), R' = H,R 2 = OH
(3aj,
(3cj,
R'
=
H,R2
= c1
( 3 d ) , R'-H2 = 0
( 3 e ) , R' = H , R~ = O ~ C - C ~ H , - C O ~ H
/3f), K' = H ,R2 = 02C-C6H4-C02Q
0
(+)-H,N-CH( C H ~ ) - C S H ~
141
a
(5)
02
16i
(3a) is stable up to 250°C in the gas phase-the degenerate
rearrangement is not manifested by this compound-and
undergoes uniform rearrangement to (6) at higher temperature. A homopentadienyl hydrogen shift of the endo 9-H
rationalizes this process.
Detection of the butadienylcyclopropane rearrangement
was accomplished with the labeled compound [D5]-(3a) (the
heavily drawn positions are deuterated) prepared in conventional manner : on H/D exchange of 2,4,6-cycloheptatrien-I ylmethyl diazomethyl ketoneI3' in [OD]-ethanol (20°C, pH
9) the diazomethyl position is labeled ; this site becomes position 10 in [D,]-(3u). Using the same technique (20"C, pH
14) the two a-methylene protons (8-H) are replaced in ( 3 d ) .
Use of LiAID4 in the subsequent stepwise reduction of the
ketone [D3]-(3d) leads to [D5]-(3u) [NMR (CDCI3, TMS
internal): olefinic H as in (3a), ~ = 6 . 9 2 (t) (7-H), 8.4 (m)
(I-H), 8.8ppm (m)(2-H)[41.Above 200°C [D,]-(Ja) undergoes
butadienylcyclopropane rearrangement in the gas phase to
54
give its labeling isomer [D5]-(3'a) with which it equilibrates
[NMR (CDCI3, TMS internal): olefinic H as in ( 3 a ) , z=6.92
(broadened t) (0.5 7-H), 8.4 (m) (I-H), 8.8 ppm (m) (2-H and
0.5 10-H)[4]].
The rearrangement established for [D5]-(3a) by isotopic
labeling converts ( 3 a ) into its mirror image (3'a). Because
of the rather unproductive route to ( 3 a ) we have determined
the kinetics of the rearrangement by polarimetry: (3b) is
converted into the half-ester ( 3 ~ (40"/,,
)
m.p. 117-119°C)
by treatment with phthalic anhydride in pyridine; reaction
of (3 e) with (+ )-a-phenylethylamine in ethanol/hexane (1 : 1)
gives the salt (3f) (79"/,, m.p. 132--135°C). After four recrystallizations from ethanol/hexane (1 : 1) a fraction of constant
melting point (46%, m.p. 141--142°C) is obtained, whose
cleavage with 5 hydrochloric acid furnishes the half-ester
(-)-(3e)["(75';/,, m.p. 119-121 "C). Reduction with LiAlH4
in ether gives the alcohol ( - ) - ( 3 b ) [97%, [2],3°=-34.50
(in CHC13)] which is transformed into the chloride and reduced
as described above. Gas chromatography of the product mixtureyields (-)-f3u) [14%, [ n y = - 10.0", [ ~ ] $ 8 ~ . , = = 19.5"
(both in n-dodecane)].
Racemization of (-)-(3a) was followed up to a loss of
at least 60% of rotatory power in 0.1 M dodecane solution
at four temperatures between 179 and 193°C. Tetralin was
added as an internal standard to the degassed samples which
were then sealed into glass ampoules; each polarimetric measurement ( h = 407.7nm) was accompanied by a gas chromatographic loss analy~is'~!
The racemization follows first order kinetics, and the temperature dependence of its rate constant
is reproduced by the Arrhenius equation
'x
logkz(13.53 *0.2)-(37800*
300)/2.303RT
The free energy of activation of the butadienylcyclopropane
rearrangement in (3a) is thus about 5.0 kcal/mol higher than
that in (f)['I. Bearing in mind that ( I ) must first be transformed
into its higher energy transoid conformer, the energy difference
for the pericyclic reaction itself in the cisoid as against the
transoid transition state should be taken as AAF* >6kcal/
mol. It remains to be established whether this difference
is overcome also in the case of (3a) by coordination to
the Fe(CO), group.
Received: October 20. 1975 [Z 345 IE]
German version: Angew Chem 88. 60 (1976)
CAS Registry numbers:
( ? ) - / 3 ~ )57674-70-1
.
: ( - ) - ( 3 < 0 ,57674-71-7: ( + )-/.?hI. 57674-72-3:
( - ) - i 3 b J . 57674-73-4; (?)-f.<c). 57674-74-5: ( 3 d j . 15719-07-0:
( ?)-(.?e)3 57674-75-6; ( - ) - / 3 e 1 . 57674-76-7: 131). 57759-53-2:
(4). 57674-17-8: i s ) , 57739-04-5
W! Grimmie and M! 1'017 E . Doering, Chem. Ber. 106, 1765 (1973).
R. Aionunn. Angew. Chem. 85. 628 (1973): Angew. Chem. Int. Ed. Engl.
12. 574 (1973).
W w n E. Dowing, B. M . Frrrier. E. 7: Fossei. J . H . Hariensrriii, M
Jones, Jr., C. Kluinpp, R. M. R u h m and M. Suunders, Tetrahedron
23, 3943 ( 1 967).
Assignment of the signals corresponds to that established by double
resonance for [ D 2 ] - ( 3 d )[ i ]
The absolute configuration or ( - ) - ( 3 v l and its reaction products is
unknown. the enantiomeric configuration ( 3 ' ) is just as likely.
Losses never exceeded lo'?,,.
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