Synthesis of syn-3a(12c),9a(9b)-dihomoperylene-3,10-dione, (E)-syn-2,2′-bi(7H-1,6-methano[10]annulenylidene)-7,7′-dione and of its rearrangement product, trans-12a, 12b-dihydro-3a(12c), 9a(9b)-dihomoperylene-3,10-dione

Article abstract of DOI:10.1039/b001786h

The main objective of the present work was to evaluate the synthesis of 1,6-methano[10]annulene derivatives of perylene and perylene-3,10-dione. The starting material for the synthetic sequence was 2,7-dibromo-1,6-methano-[10]annulene (I), which was converted by methoxy- and ethoxy-debromination S_NAr-type reactions to 2-bromo-7-methoxy- and -7-ethoxy-1,6-methano[10]annulenes (II). The reactions were much more facile than those of the apparently similar halogenonaphthalenes. Compounds II were reductively coupled, using a Ni(0) complex, to give isomeric mixtures of rac- and meso-7,7-dimethoxy- and -diethoxy-2,2′-bi(1,6-methano[10]annulenyl)s (IIIA and IIIB). Oxidative coupling of a mixture of compounds IIIA and IIIB with thallium(in) trifluoroacetate in acetonitrile gave (E)-syn-2,2′-bi(7H-1,6-methano[10]annulenylidene)-7,7′-dione IV as the main reaction product, accompanied by a small amount of syn-3a(12c),9a(9b)-dihomoperylene-3,10-dione, VI. Subsequent experiments showed that the meso-form (IIIB) produced the syH-dihomoperylenedione (VI); while the rac-form (IIIA) gave (E)-syn-2,2???-bi(7H-1,6-methano[10]annulenylidene)-7,7′-dione IV. The low yield of the dihomoperylenedione suggests decomposition reactions occur, with various by-products remaining undetected. A solution of the annulene-quinone (IV) in carbon tetrachloride, when refluxed and illuminated rearranged to give trans-12a,12b-dihydro-3a(12c),9a(9b)dihomoperylene-3,10-dione (V). The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b001786h

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Synthesis of syn-3a(12c),9a(9b)-dihomoperylene-3,10-dione,
(E)-syn-2,2Ј-bi(7H-1,6-methano[10]annulenylidene)-7,7Ј-dione
and of its rearrangement product, trans-12a,12b-dihydro-
3a(12c),9a(9b)-dihomoperylene-3,10-dione
1
Aderson de Farias Dias,a Thomas Helwig,b Johann Lex,b Joseph Miller*a and
Hans Schmicklerb
a Universidade Federal da Paraiba/Laboratório de Tecnologia Farmacêutica, Campus I,
Caixa Postal 5009, 58051-970 João Pessoa PB, Brazil
b Institut für Organische Chemie der Universität Köln, Greinstraße 4, 50939 Köln, Germany
Received (in Cambridge, UK) 6th March 2000, Accepted 4th April 2000
Published on the Web 13th June 2000
The main objective of the present work was to evaluate the synthesis of 1,6-methano[10]annulene derivatives of
perylene and perylene-3,10-dione. The starting material for the synthetic sequence was 2,7-dibromo-1,6-methano-
[10]annulene (I), which was converted by methoxy- and ethoxy-debromination SNAr-type reactions to 2-bromo-7-
methoxy- and -7-ethoxy-1,6-methano[10]annulenes (II). The reactions were much more facile than those of the
apparently similar halogenonaphthalenes. Compounds II were reductively coupled, using a Ni(0) complex, to give
isomeric mixtures of rac- and meso-7,7-dimethoxy- and -diethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)s (IIIA and
IIIB). Oxidative coupling of a mixture of compounds IIIA and IIIB with thallium(III) trifluoroacetate in acetonitrile
gave (E)-syn-2,2Ј-bi(7H-1,6-methano[10]annulenylidene)-7,7Ј-dione IV as the main reaction product, accompanied
by a small amount of syn-3a(12c),9a(9b)-dihomoperylene-3,10-dione, VI. Subsequent experiments showed that the
meso-form (IIIB) produced the syn-dihomoperylenedione (VI); while the rac-form (IIIA) gave (E)-syn-2,2Ј-bi(7H-
1,6-methano[10]annulenylidene)-7,7Ј-dione IV. The low yield of the dihomoperylenedione suggests decomposition
reactions occur, with various by-products remaining undetected. A solution of the annulene-quinone (IV) in
carbon tetrachloride, when refluxed and illuminated rearranged to give trans-12a,12b-dihydro-3a(12c),9a(9b)-
dihomoperylene-3,10-dione (V).
iodide are similar.6 We can therefore confidently ascribe the
much greater facility of the reactions to the markedly greater
stabilization of the intermediate (σ) complexes and their
flanking transition states, resulting from full delocalization of
π-electrons and negative charge over the 10-membered ring.
This is supported by the formation of monoalkoxy bromo
products cleanly in good yield. This is a consequence of the
Introduction
The present work describes the synthesis and structural deter-
mination of the title compounds and corresponding inter-
mediates. They have not previously been reported in the
literature, where there are but few references to bi(annulenyl)
derivatives.1–4
transmission of the deactivating effect of the entering alkoxy
group via the π-system of the 10-membered ring from the 2- to
the 7-position.
Discussion
The synthetic sequence used to obtain the title compounds
is shown in Scheme 1, in which RO = MeO and EtO. The
starting material was 2,7-dibromo-1,6-methano[10]annulene
(I). Methoxide and ethoxide ions were used in parallel
reactions.
In the second step the bromoalkoxyannulenes were reduc-
tively coupled using tetrakis(triphenylphosphine)nickel(0).
This reagent was prepared in situ (see Experimental section).
This reaction led to a mixture of rac- and meso-7,7Ј-dialkoxy-
2,2Ј-bi(1,6-methano[10]annulenyl)s (IIIA and IIIB).
The first step in the synthetic sequence is an SNAr type
alkoxy-debromination reaction forming 2-bromo-7-alkoxy-1,6-
methano[10]annulenes cleanly in good yields. It is noteworthy
that the reactions proceed under very mild conditions. This
is in marked contrast with alkoxy-dehalogenation reactions
of simple halogenobenzenes and halogenonaphthalenes.
For example, the methoxy-dechlorination (MeOϪ–MeOH)
of chlorobenzene proceeds slowly even close to the critical
temperature of the solvent (232 ЊC).5 The admixture in our
reactions of a dipolar aprotic solvent can contribute only
modestly to the difference. It is relevant that (a) halogenonaph-
thalenes are a little more reactive then corresponding halogeno-
benzenes, (b) a second halogen has only a weak activating effect
and (c) the leaving group mobilities of chloride, bromide and
While the reaction with the bromoethoxy compound had the
advantage of better solubility we could not separate the rac-
and meso-forms. However this was possible with the bromo-
methoxy compound, as confirmed by X-ray diffraction (Fig.
1a,b), so that it was used for the next stage of the synthetic
sequence (Scheme 1).
The rac-form of 7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) (IIIA) was oxidized with thallium() trifluoro-
acetate (TTFA) in anhydrous acetonitrile forming (E)-syn-2,2Ј-
bi(7H-1,6-methano[10]annulenylidene)-7,7Ј-dione (IV) in 60%
yield.
When dissolved in carbon tetrachloride and refluxed in
daylight, it underwent a rearrangement, accompanied by a
colour change from violet to yellow. It gave a 50% isolated yield
DOI: 10.1039/b001786h
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This journal is © The Royal Society of Chemistry 2000
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Scheme 1 Reagents and conditions: (A) ROϪ in HMPT (2:1 v/v) at 40 ЊC; (B) Ni(0)(PPh3)4 prepared in situ, in THF; (C) Tl()(CF3CO2)3 in
anhydrous CH3CN; (D) hv and ∆ in CCl4. The separate reaction of rac- and meso-forms (IIIA, IIIB) was possible only with OR = OMe.
Scheme 2 Preparation of rac- and meso-forms (IIIA and IIIB) by oxidative coupling of the lithium compound IIB.
of trans-12a,12b-dihydro-3a(12c),9a(9b)-dihomoperylene-3,10-
dione (V), as confirmed by X-ray diffraction (Fig. 1d) and
spectral data.
We also carried out oxidative, instead of reductive, coupling
of the bromoalkoxy annulenes: oxidative coupling has been
used by Rapson and by Wittig and their co-workers7,8 for some
other syntheses.
In our oxidative reactions (Scheme 2) we obtained a 30%
yield of a mixture of rac- and meso-7,7Ј-dimethoxy-2,2Ј-bi-
(1,6-methano[10]annulenyl)s. This compared with 52% yield by
the reductive coupling method.
absorbs as a triplet centred at 7.14 ppm. Signals at δ = 6.83
and 6.51 can be assigned to H-9 and H-8. H-3 is responsible for
the very broad signal at δ = 7.39–7.48. The protons of the
methylene bridge absorb as an AB-system at δ = 0.07 and Ϫ0.43
(H-11a, H-11b). The methyl protons produce a singlet at
δ = 3.88.
At Ϫ40 ЊC the two conformational isomers (R1 and R2) exist
1
side by side. The assignment of the H NMR signals is shown
in Table 1. The protons H-3 in R1 and H-9 and H-10 in R2
are shifted to a higher field due to the shielding effect of the
other annulenyl group. On the other hand, the protons H-3 of
R2 and H-9/H-10 of R1 are shifted downfield due to the
deshielding effect of the other annulenyl moiety. The difference
in the chemical shifts for H-3 amounts to 1.18 ppm, for H-9,
0.41 ppm and for H-10, 1.52 ppm. R1 is probably the
rotational isomer (IIIAa) or (IIIAc). NMR analysis does not
serve to distinguish between them.
The twisting of the arene moieties in solution is greater than
in the crystal, so that the torsion angle of approximately 36Њ
determined by crystallography indicates the existence of
(IIIAa).
When
meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) was oxidized by thallium() trifluoroacetate we
obtained a 32% yield of syn-3a(12c),9a(9b)-dihomoperylene-
3,10-dione (VI), confirmed by X-ray (Fig. 1c) and spectral data.
We also carried out the oxidation with vanadium() oxytri-
fluoride in anhydrous CH2Cl2. The same product was obtained
but in only 18% yield.
In the temperature-dependent 1H NMR spectrum of the
racemic bi(annulenyl)s we observe at ambient temperature a
singlet for the methyl group at 3.88 ppm, as well as two doublets
at 7.67 ppm for H-5 and at Ϫ0.52 ppm for H-11b.
The stereoisomers (IIIAb) and (IIIAd) are considered to be
R2. As with R1 no decision can be made, on the basis of the
1H NMR spectrum, in favour of (IIIAb) or (IIIAd). At 22 ЊC
At 100 ЊC the protons H-3 and H-10 exhibit only broad
absorptions. H-5 appears as a doublet with δ = 7.76; H-4
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Fig. 1 X-Ray structures of (a) rac-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]annulenyl) (IIIA), (b) meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano-
[10]annulenyl) (IIIB), (c) syn-3a(12c),9a(9b)-dihomoperylene-3,10-dione (VI), and (d) trans-12a,12b-dihydro-3a(12c),9a(9b)-dihomoperylene-3,10-
dione (V).
the signals of H-11b coalesce, equivalent to a rotational barrier
signals, corresponding to the existence of the pairs of enantio-
mers (IIIBa)/(IIIBb) and (IIIBc)/(IIIBd), respectively (Fig. 2).
The resonance absorptions of the isomers are given in Table 1.
Despite our inability to separate the rac- and meso-forms of
7,7Ј-diethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)s we decided
to repeat the second part of the synthetic sequence with the
mixture. This proceeded well and we obtained the same product
(vide supra).
Torsional isomerism involving planar chiral structures has
been studied extensively.9 In addition to torsional isomerism,
the compounds described in this paper are characterized by the
so-called “annulene chirality”.10 As a consequence, the coupling
of II produces a diastereomeric mixture of rac-IIIA and
meso-IIIB.
of 15 kcal molϪ1
.
1
The H NMR spectrum of the meso-form (IIIB) shows a
broad absorption for H-10 at ambient temperature due to the
lower activation enthalpy for the racemization. At 40 ЊC the
rapid interchange of the stereoisomers causes the signals of
the protons of (IIIB) to exchange quickly. H-5 generates a
doublet δ = 7.59, H-3 absorbs at 7.14 ppm as a doublet. The
protons H-8, H-9 and H-10 absorb at 6.46, 6.78 and 6.54 ppm.
The methyl group appears at 3.89 ppm and the bridge-protons
form an AB system with δ = 0.04 and Ϫ0.52 (H-11a, H-11b).
At Ϫ100 ЊC the interchange of the stereoisomers of (IIIB) is
very slow.
1
In the H NMR spectrum, one can recognize 18 different
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Table 1 1H NMR chemical shifts (ppm) and coupling constants (Hz) of IIIA and IIIB (300 MHz, THF-d8 at T = Ϫ100 to Ϫ50 ЊC and THF-d8–
C2D2Cl4 at T = 50–100 ЊC
H-3/H-3Ј
H-4/H-4Ј
H-5/H-5Ј
H-8/H-8Ј
H-9/H-9Ј
H-10/H-10Ј O–CH3/O–CH3Ј
H-11a/H-11aЈ
H-11b/H-11bЈ
IIIBa
7.14
7.05
7.59
6.46
6.78
6.54
3.89
0.04
Ϫ0.52
JAB = Ϫ9.7
J3,4 = 9.9; J4,5 = 8.0
6.99/
J8,9 = 9.8; J9,10 = 9.5
M1
6.64/
7.75
7.57/
7.62
6.64/
6.36
7.17/
6.53
7.70/
5.34
3.98/
3.77
0.11/
Ϫ0.05
Ϫ0.62
Ϫ0.75
M2b
7.35
J3,4 = 9.9; J4,5 = 8.0
J8,9 = 9.8; J9,10 = 9.5
JAB = Ϫ9.7
JAB = Ϫ9.7
Ϫ0.43
JAB = Ϫ9.7
Ϫ0.61
JAB = Ϫ9.7
Ϫ0.61
JAB = Ϫ9.7
IIIAc
R1d
7.39–7.48
7.14
J4,5 = 8.4
7.15
7.67
7.71
7.73
6.51
6.66
6.55
6.83
J8,9 = 9.8
7.12
7.11–7.17
8.00
3.88
3.86
3.78
0.07
0.11
6.93
J3,4 = 9.8; J4,5 = 8.2
J8,9 = 9.7; J9,10 = 9.3
R2d
8.11
7.34
6.71
6.48
Ϫ0.02
J3,4 = 9.98; J4,5 = 8.2
J8,9 = 9.4; J9,10 = 9.8
a T = 40 ЊC. b T = Ϫ100 ЊC. c T = 100 ЊC. d T = Ϫ40 ЊC; M1, M2 = rotational isomers of IIIB; R1, R2 = rotational isomers of IIIA.
Fig. 2 syn- and anti-stereoisomers of rac-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]annulenyl) and meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) (IIIA/IIIB).
The rotational isomers IIIBa and b, c and d are pairs of
enantiomers and in achiral solvents should exhibit identical
NMR spectra, whereas IIIAa and c, and b and d are diastereo-
isomers and so may have different NMR spectra.
positions are always equivalent. The atropisomers of the
rac-form IIIA are diastereoisomers and should have different
spectra.
With a torsion angle of 0Њ, IIIB belongs to symmetry group
Cs, while a rotation of 180Њ changes it to the Ci point group. As
a consequence in both cases the protons of the corresponding
positions in the annulenyl moieties (that is, H-3 and H-3Ј,
H-4 and H-4Ј, etc.) are magnetically equivalent and absorb at
the same frequency in the NMR spectrum.
At any other torsion angle the symmetry decreases to C1
and the structure becomes asymmetric. Consequently the
protons at the corresponding positions are diastereotopic with
differences in chemical shifts. With any torsion angle between
0Њ and 360Њ IIIA has a C2-axis. The protons at corresponding
Experimental
1H and 13C NMR spectra were recorded on a Bruker AM 300
or a VARIAN EM 390 spectrometer. Mass spectra were
recorded using Finningan 3000 Datensystem 6100, VARIAN
MAT 212, Datensystem 6100 SS 200 and VARIAN MAT
CH7A Datensystem SS 200 spectrometers. UV spectra were
recorded on a Beckmann MUI spectrometer. IR spectra
were recorded on a Perkin-Elmer 283 spectrometer. X-Ray dif-
fraction studies were performed on an Enraf-Nonius CAD-4
diffractometer.
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X-Ray analysis†
anol (100 ml) and treated with methanolic sodium methoxide
solution (prepared by reaction of metallic sodium (12 g, 0.52
mol) in 120 ml of anhydrous methanol). The reaction mixture
was stirred at 30 ЊC for two days and was then quenched with a
saturated solution of NiCl2. Stirring was continued for a further
half-hour and the reaction mixture was then extracted with
diethyl ether (5 × 250 ml). The ether extract was washed with
water (2 × 100 ml) and dried over anhydrous sodium sulfate.
The yellow viscous residue was chromatographed over Al2O3
(Brockmann) and eluted with hexane. The first fraction con-
sisted of unchanged starting material (3.1 g, 10%). Elution with
hexane–dichloromethane (8:2 v/v) furnished the desired
compound 2-bromo-7-methoxy-1,6-methano[10]annulene II as
a yellow oil (19.4 g, 77.5%). Elution with hexane–dichloro-
methane (1:1) then yielded 2,7-dimethoxy-1,6-methano[10]-
annulene (2.4 g, 12%) as a crystalline compound with melting
point 66–66.5 ЊC.
The configurations of rac- and meso-compounds (IIIA and
IIIB), as well as of syn-3a(12c),9a(9b)-dihomoperylene-3,10-
dione (VI) and the rearrangement product trans-12a,12b-
dihydro-3a(12c),9a(9b)-dihomoperylene-3,10-dione (V) were
established on the basis of their X-ray crystallographic analysis.
The crystal structures were solved by direct methods and
refined by full matrix least squares with anisotropic thermal
parameters for C and O and isotropic thermal parameters
for H.
1. meso-7,7Ј-Dimethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)
(IIIB). C24H22O2, M 342.45, d (calcd) = 1.268 g cmϪ3, µ = 0.73
cmϪ1, number of independent reflections (I > 3σ(I) 4039), space
¯
group P1, a = 12.625(3), b = 12.775(3), c = 12.798(3) Å, α =
86.67(2), β = 79.32(2), γ = 62.29(2)Њ, V = 1794.7 Å3.
The compound crystallizes in the triclinic form with 4
molecules per unit cell in two independent isomeric conform-
ations with different torsion angles (C-1–C-2–C-2Ј–C-1Ј). For
meso-IIIBa the angle is 69.5Њ and for IIIBb it is 55.9Њ. The final
R value was 0.039.
Elemental analysis: C12H11BrO [251.11], calculated: C =
57.39, H = 4.41. Found: C = 57.7, H = 4.4%. δH (90 MHz; CCl4–
TMS) Ϫ0.4, 0.16 (AB system, 2 H, methylene bridge), Ϫ0.46
(d, H-11a, Ja,b = 10 Hz), 0.1 (d, H-11b, Jb,a = 10.5 Hz), 3.94
(s, OCH3), 6.5–7.76 (m, 6 H, peripheral protons, two super-
imposed ABC systems); δH (300 MHz; CD3CN) 7.54 (J5,11b
=
2.
rac-7,7Ј-Dimethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)
0.9 Hz, H-5), 7.31 (J3,4 = 10.2 Hz, H-3), 7.25 (J10,11a = 1.2 Hz,
H-10), 7.00 (J9,10 = 9.8 Hz, H-9), 6.99 (J4,5 = 8.1 Hz, H-4), 6.48
(J8,9 = 9.8 Hz, H-8), 3.75 (OCH3), 0.75 (H-11a), 0.05 (H-11b)
(IIIA). The title compound crystallizes in the monoclinic
form in the space group P21/c with 4 molecules per unit cell,
in a conformation similar to rac-structure IIIAa. The torsion
angle of 36Њ is smaller than that of the meso-compound and
the C-2–C-2Ј bond length is 0.01 Å shorter than in meso-IIIB.
C24H22O2, M 342.45, d (calcd.) = 1.284 g cmϪ3, a = 8.847, b =
12.812, c = 15.629 Å, β = 91.72Њ, torsion angles C-1–C-2–C-2Ј–
C-1Ј 39.9Њ, C-1–C-2–C-2Ј–C-3Ј Ϫ143.2Њ, C-3–C-2–C-2Ј–C-3Ј
31.2, C-3–C-2–C-2Ј–C-1Ј Ϫ145.7Њ. The final R value was 0.040.
The number of independent reflections with I > 2σ(I) was 1971.
Evidence for the predicted non-equivalence of protons H-3
and H-3Ј, H-4 and H-4Ј of the meso-compound can be deduced
from its X-ray crystal structure.
(J11a,1b = Ϫ10.5 Hz, gem); m/z (70 eV) 250, 252 (8.6, 8.9%)
[M] ϩ, 171 (36%) [M Ϫ Br]ϩ, 140 (9%) [M Ϫ Br Ϫ OCH3]
,
ϩ
᝽
᝽
128 (100%) [M Ϫ Br Ϫ OCH3 Ϫ CH2] ϩ. ν(KBr)/cmϪ1 3047,
᝽
3005 and 2952 (C–H stretching), 1576 (C᎐C stretching), 1251
᎐
(C–O stretching); λ(dichloromethane)/nm 265 (ε = 40289), 310
(5212), 330 (6622), 415 (1238).
Similarly 2,7-dibromo-1,6-methano[10]annulene (30 g, 0.1
mol) was dissolved in HMPT (200 ml) and treated at ambient
temperature with an ethanolic sodium ethoxide solution
(prepared by reacting metallic sodium (2.3 g, 0.1 mol) in 100 ml
anhydrous ethanol). The deep brown mixture was stirred during
5 hours at 40 ЊC and then overnight at ambient temperature.
The work-up was effected according to the procedure for
the reaction with sodium methoxide. Very little unchanged
starting material was isolated in the first fraction. The next
main fraction was evaporated and the oily residue was distilled
under vacuum and consisted of the desired product 2-bromo-7-
ethoxy-1,6-methano[10]annulene, IIA, in the form of a yellow
oil (23.7 g, 90% yield). The third fraction (2.3 g, 6%) consisted
of a highly viscous oil, which was identified as 2,7-diethoxy-1,6-
methano[10]annulene. It solidified on standing at Ϫ25 ЊC.
The smaller torsion angle of 26.7Њ for the rac-form than the
average values for meso-forms IIIBa and b suggests that
the conjugative interaction through the C-2–C-2Ј bond is more
significant in rac- than in meso-compounds.
3. syn-3a(12c),9a(9b)-Dihomoperylene-3,10-dione (VI). Com-
pound VI crystallizes in the monoclinic form in the space group
P21/c with 4 molecules per unit cell. The central 6-membered
ring lies in the conformation of a flat tub and its benzenoid
character is evident in the C-6a–C-6b bond length of 1.476 Å
in syn-dihomoperylene11 and of 1.429 Å in VI. C22H14O2, M
310.36, d (calcd.) = 1.383 g cmϪ3, µ = 0.817 cmϪ1, a = 15.389(4),
b = 11.183(3), c = 8.838(2) Å, α = 90, β = 101.61(2), γ = 90Њ,
V = 1489.9 Å3. The final R value was 0.048 and the number
of independent reflections with I > 2σ(I) was 3092.
rac- and meso-7,7Ј-dimethoxy-2,2Ј-bis(1,6-methano[10]-
annulenyl)s
(a) Oxidative coupling of 2-bromo-7-methoxy-1,6-methano-
[10]annulenes (II) with CuCl2. Compound IIA (8.5 g, 33 mmol)
was dissolved in anhydrous diethyl ether (100 ml) and treated
at Ϫ50 ЊC with an ethereal solution of n-butyllithium (33 ml,
33 mmol). The mixture was stirred and transferred via cannula
to a precooled suspension of copper() chloride (4.6 g, 34 mmol)
in anhydrous diethyl ether (300 ml). The temperature of the
reaction mixture was maintained at Ϫ78 ЊC while the reaction
was stirred for 6 hours. It was then quenched with cold water
(5 ml) and decanted over folded filter paper. The solid inorganic
residue was washed with diethyl ether (2 × 50 ml) and the com-
bined ethereal solutions were washed with water (4 × 50 ml)
and dried over anhydrous sodium sulfate. After evaporation of
the solvent the solid residue was chromatographed over Al2O3
(Woelm, activity III, l = 80 cm, id = 3 cm). Elution with hexane–
dichloromethane (8:2) yielded a bright yellow fraction from
which 1.73 g (30%) of a crystalline yellow substance (mixture
of both rac- and meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano-
[10]annulenyl)s) was obtained.
4.
trans-12a,12b-Dihydro-3a(12c),9a(9b)-dihomoperylene-
3,10-dione (V). The anti-configuration of the methylene bridges,
the norcaradiene structure and the trans cyclization at C-12a–
C-12b are important stereochemical features shown in Fig. 1d.
The average of the bond lengths C-3a–C-12c and C-9a–C-9b is
equal to 1.586 Å and is coherent with the cyclopropane rings
of the norcaradiene form. C22H16O2, M 312.37, a = 9.226(2),
b = 11.375(3), c = 15.582(4) Å, α = 109.90(2), β = 98.37(2),
3
¯
γ = 90.04(2)Њ, V = 1519 Å , Z = 4, triclinic, space group P1, d
(calcd.) = 1.366 g cmϪ3, µ = 0.81 cmϪ1, number of reflections
I > 3σ(I): 3665, R = 0.056.
2-Bromo-7-methoxy-1,6-methano[10]annulene
2,7-Dibromo-1,6-methano[10]annulene (15 g, 50 mmol) was
dissolved in a mixture of anhydrous HMPT (20 ml) and meth-
† CCDC reference number 207/423.
J. Chem. Soc., Perkin Trans. 1, 2000, 2083–2089
2087

View Article Online
(b) Reductive coupling of 2-bromo-7-methoxy-1,6-methano-
[10]annulene (II) with [Ni(PPh3)2Cl2]–Zn–Et4NI–THF.
Because of hindrance to rotation, the rac-form exhibits a
rather broad absorption pattern for the peripheral protons. H-3
and H-10 from two of the four rotational isomers appear at
δ 8.05–8.15 and 7.9–8.0, respectively. H-11a and H-11b absorb
at δ 0.08 and Ϫ0.2.
Dichlorobis(triphenylphosphine)nickel() (13 g, 20 mmol),
activated zinc (2.612 g, 40 mmol) and tetraethylammonium
iodide (5.138 g, 20 mmol) were mixed together and dried by
heating in an oil bath at 100 ЊC for four hours under vacuum
(0.1 Torr). Anhydrous THF (100 ml) was added at ambient
temperature and the suspension was sonicated to accelerate
complex formation. Then a solution of II (5 g, 19 mmol) in
anhydrous THF (50 ml) was added via cannula to the nickel
complex suspension and the resultant reaction mixture was
further sonicated for 6 hours. The mixture was passed through a
sintered filter and the sediment was washed with ethyl ether
(5 × 20 ml). The solution was dried over sodium sulfate, the
solvent was evaporated and the residue was chromatographed
over Al2O3 (Woelm, activity III, l = 50 cm, id = 2.5 cm). Elution
with hexane gave triphenylphosphine and with hexane–
dichloromethane (8:2) furnished the mixture of isomers (2.99
g, 52%) in an approximate ratio of 1:1.
Pure rac-IIIA (mp 195–196 ЊC) was obtained by recrystalliz-
ation from anhydrous ethanol while the meso-form (mp 122–
123 ЊC) was purified by column chromatography over silica gel
of the IIIB enriched mother liquor from IIIA. Elution with
pentane–tert-butyl methyl ether (97:3) produced firstly the
meso-compound and further elution produced the rac-form
(IIIA).
(Found: 370.1935. Calc. for C26H26O2: 370.1933); δH (300
MHz; CDCl3) of the mixture of rac- and meso-7,7Ј-diethoxy-
2,2Ј-bi(1,6-methano[10]annulenyl)s (IIIC, D): 8.15–8.05 (H-3
of R1*), 8.00–7.90 (H-10 of R2*), 7.76 (d, H-5, rac-form),
7.65 (d, H-5, meso-form), 7.25–7.05 (m, H-3, H-4, meso-form),
6.81 (t, H-9, meso-form), 6.60–6.50 (br d, H-10, meso-form),
6.47 (d, H-8, meso-form), 4.40–3.80 (m, methylene protons),
1.40 (m, methyl protons), 0.08–0.20 (H-11a, rac-form), 0.03
(dd, H-11a, meso-form), Ϫ0.47 (d, H-11b, rac-form);
λ(CH2Cl2)/nm 384 (ε/dm3 molϪ1 cmϪ1 = 11800), 275 (ε = 52000),
260 (ε = 62400); ν(film)/cmϪ1 3044 (᎐C–H stretching), 2984 and
᎐
2949 (–C–H stretching), 1568, 1531 and 1499 (C᎐C stretching),
᎐
1252 (C–O stretching); m/z (70 eV) 370 (7%) [M] ϩ, 356 (1%)
᝽
[M Ϫ CH2] ϩ, 355 (1%) [M Ϫ CH3]ϩ, 341 (5%) [M Ϫ C2H5]ϩ,
᝽
325 (2%), 313 (6%) [M Ϫ C2H5 Ϫ CO] ϩ, 297 (14%) [M Ϫ
᝽
OC2H5 Ϫ C2H4] ϩ, 280 (5%) [M Ϫ 2OC2H5] ϩ, 252 (36%)
᝽
᝽
[M Ϫ 2OC2H5 Ϫ 2CH2] ϩ, 239 (58%), 226 (30%), 215 (34%),
᝽
202 (26%), 185 (25%), 55 (100%); * rotational isomers.
syn-3a(12c),9a(9b)-Dihomoperylene-3,10-dione (VI)
Oxidation of meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) (IIIB) with Tl(OCOCF3)3. Thallium trifluoro-
acetate (Aldrich, 560 mg, 1.0 mmol) was dissolved in anhydrous
acetonitrile (50 ml) and maintained at Ϫ40 ЊC under inert gas.
A solution of the meso-compound (IIIB) (140 mg, 0.4 mmol)
in carbon tetrachloride was then added and stirring was
maintained for 1 hour at the same temperature. The solvent
was evaporated at 0 ЊC under vacuum and the residue was
filtered through a short path column (l = 25 cm, id = 3 cm).
Recrystallization from diethyl ether afforded the title com-
pound (VI) (40 mg, 32%) as orange coloured needles which
decomposed at 250 ЊC without melting.
rac- and meso-7,7Ј-Diethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)s
(IIIC, D)
The isomeric mixture of compounds IIIC and IIID was
obtained through reductive coupling of 2-bromo-7-ethoxy-1,6-
methano[10]annulene with the nickel(0) complex according
to the procedure described for obtaining the rac- and meso-7,7Ј-
dimethoxy-2,2Ј-bi(1,6-methano[10]annulenyl)s (IIIA, B). The
isomeric mixture was purified by column chromatography
on Al2O3 (Woelm, activity III, l = 40 cm, diam. = 4.0 cm) with
hexane as the mobile phase. The title compounds were obtained
as a hard yellow wax of melting point 55–57 ЊC, yield 1.92 g
(69%), which could not be separated into the pure isomers
through conventional methods.
Oxidation of meso-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) (IIIB) with VOF3. Vanadium() oxytrifluoride,
VOF3 (150 mg, 1.2 mmol) suspended in anhydrous dichloro-
methane was treated dropwise with a solution of the meso-
compound (IIIB) (140 mg, 0.4 mmol) in dichloromethane
under inert gas. The reaction mixture was stirred for 1 hour
at ambient temperature and quenched with a 5% solution of
sodium hydrogen carbonate (25 ml). The organic phase was
washed with 5% sodium hydrogen carbonate (2 × 25 ml), then
with water (3 × 50 ml) and dried over magnesium sulfate. After
evaporation of the solvent the residue was chromatographed
over silica gel (l = 25 cm, id = 3 cm) with diethyl ether. It
yielded 22 mg (18%) of syn-3a(12c),9a(9b)-dihomoperylene-
3,10-dione (VI).
meso-Form. Found: 342.16. Calc. for C24H22O2: 342.43;
λ(CH2Cl2)/nm 252.5 (ε/dm3 cmϪ1 molϪ1 = 61613), 277 (ε = 4648),
370 (ε = 16002); ν(CsI)/cmϪ1 3047 and 3010 (᎐C–H stretching),
᎐
1532 and 1500 (C᎐C stretching), 1252 (C–O stretching); m/z
᎐
(70 eV) 342 (<1%) [M] ϩ, 327 (<1%) [M Ϫ CH3]ϩ, 311 (<1%)
᝽
[M Ϫ OCH3]ϩ, 296 (<1%) [M Ϫ OCH3 Ϫ CH3]ϩ, 280 (<1%)
[M Ϫ 2OCH3] ϩ, 266 (5%) [M Ϫ 2OCH3 Ϫ CH2] ϩ, 252 (8%)
᝽
᝽
[M Ϫ 2OCH3 Ϫ 2CH2] ϩ, 239 (17%), 113 (26%), 45 (100%);
᝽
δH (300 MHz; THF-d8) 7.14 (H-3/H-3Ј), 7.05 (H-4/H-4Ј), 7.59
(H-5/H-5Ј), 6.46 (H-8/H-8Ј), 6.78 (H-9/H-9Ј), 6.54 (H-10/H-10Ј),
3.89 (O–CH3/O–CH3Ј), 0.04 (H-11a/H-11aЈ), Ϫ0.52 (H-11b/H-
11bЈ) (J3,4 = 9.9; J4,5 = 8.0; J8.9 = 9.8; J9,10 = 9.5; JAB = 9.75 Hz).
rac-Form. (Found: C, 84.1; H, 6.6. Calc. for C24H22O2: C,
(Found: C, 84.95; H, 4.5. Calc. for C22H12O2: C, 85.14; H,
4.55%); δH (300 MHz; CD2Cl2) 6.35 (H-4,9), 7.13 (H-5,8), 8.10
(H-6,7) (parts A, M and X of an AMX-system), 6.28 (H-2,11),
7.60 (H-1,12) (parts A and X of an AX-system), 1.48 (H-
13b,14b), 3.97 (H-13a,14a) (parts A and X of an AX-system);
84.18; H, 6.48%); λ(CH2Cl2)/nm 371 (ε/dm3 molϪ1 cmϪ1
=
16100), 275 (ε = 42300), 253 (ε = 56800); ν(KBr)/cmϪ1 3051
and 3010 (᎐C–H stretching), 2967, 2945 and 2839 (–C–H
᎐
stretching), 1532 and 1502 (C᎐C stretching), 1253 (C–O stretch-
᎐
ing); m/z (70 eV) 342 (<1%) [M] ϩ, 327 (<1%) [M Ϫ CH3]ϩ,
(J1,2 = J11,12 = 11.84; J4,5 = J8,9 = 5.23; J4,6 = J7,9 = 0.12; J5,6 = J7,8
11.23; J13a,13b = J14a,14b = Ϫ10.89; J4,13a = J9,14a = 0.08; J4,13b
=
=
᝽
ϩ
280 (<1%) [M Ϫ 2OCH3]
,
252 (20%) [M Ϫ 2OCH3 Ϫ
᝽
2CH2] ϩ, 239 (34%), 113 (100%); δH (300 MHz; THF-d8) (IIIB)
7.67 (H-5), 7.39–7.48 (H-3), 7.14 (H-4), 7.11–7.17 (H-10), 6.83
(H-9), 6.51 (H-8), 3.88 (O–CH3), 0.07 (H-11a), Ϫ0.43 (H-11B)
(J4,5 = 8.4; J8,9 = 9.8; JAB = 9.7).
J9,14b = 0.66; RMS-error = 0.03 Hz); δC (75.5 MHz; CD2Cl2)
᝽
1
189.52 (C-3,10), 133.94 (C-1,12, JC-H = 162.4), 132.88 (C-6,7,
1JC-H = 158.5, 2JC-H = 7.6), 130.73 (C-2,11, 1JC-H = 162.4), 129.13
1
1
(C-5,8, JC-H = 159.9), 121.74 (C-4,9, JC-H = 162.1), 117.81
1
2
In the meso-form the proton H-5 appears as a doublet at
7.65 ppm while H-3 and H-4 absorb as a multiplet at δ 7.05–
7.25. H-9 absorbs as a triplet at δ 6.81 and H-8 appears at
δ 6.47 as a doublet. At δ 6.5–6.6 H-10 absorbs as a broad
doublet and H-11a, H-11b appear at 0.03 and Ϫ0.52 ppm,
respectively.
(C-3a,9a), 33.16 (C-13,14, JC-H = 139.1, JC-H = 6.9), 134.54,
129.18 and 128.85 (C-6a,6b,9b,12a,12b,12c); λ(dioxane)/nm
467w (ε/dm3 molϪ1 cmϪ1 = 1500), 393 (ε = 20300), 343 (ε =
16000), 239 (ε = 25600); ν(CsI)/cmϪ1 3144 (᎐C–H stretching),
᎐
2931 (–C–H stretching), 1644 (C᎐O stretching), 1587, 1577,
᎐
1543 and 1300 (C᎐C stretching), 836, 827 and 820 (᎐C–H def.);
᎐
᎐
2088
J. Chem. Soc., Perkin Trans. 1, 2000, 2083–2089

View Article Online
m/z (70 eV) 310 (12%) [M] ϩ, 309 (3%) [M Ϫ H]ϩ, 281 (17%)
J11,12 = 10.8;
J4,5 = J8,9 = 9.2;
J5,7 = J7,8 = 6.4;
J13a,13b =
᝽
[M Ϫ H Ϫ CO] ϩ, 252 (39%) [M Ϫ 2H Ϫ 2CO] ϩ, 239 (49%)
J14a,14b = 4); δC (75.5 MHz; CD2Cl2) 193.07 (C-3,10), 142.37
᝽
᝽
[M Ϫ H Ϫ 2CO Ϫ CH2]ϩ, 226 (38%) [M Ϫ 2CO Ϫ 2CH2]ϩ, 125
(C-1,12, JC-H = 164.0), 139.25 (C-6a,6b), 127.50 (C-2,11,
1
1
(51%), 44 (100%).
1JC-H = 165.4), 122.18 (C-4,9, JC-H = 167.0), 121.02 (C-5,8,
1JC-H = 161.7), 117.69 (C-6,7, JC-H = 161.7, JC-H = 9.9), 43.51
1
2
1
(C-9b,12c), 43.29 (C-12a,12b, JC-H = 134.0), 41.18 (C-3a,9a),
(E)-syn-2,2Ј-Bi(7H-1,6-methano[10]annulenylidene)-7,7Ј-dione
(IV)
1
22.74 (C-13,14, JC-H = 166.1 and 168.8); m/z (70 eV) 312 (8%)
[M] ϩ, 311 (3%) [M Ϫ H]ϩ, 297 (5%) [M Ϫ H Ϫ CH2]ϩ, 283
᝽
Oxidation of rac-7,7Ј-dimethoxy-2,2Ј-bi(1,6-methano[10]-
annulenyl) (IIIA) with thallium trifluoroacetate, Tl(OCOCF3)3.
The procedure used for the oxidation of the meso-form
IIIB was also used in this case. Compound IV was obtained in
60% yield (95 mg) in the form of deep violet crystals of mp
119–120 ЊC.
(12%) [M Ϫ H Ϫ CO] ϩ, 269 (24%) [M Ϫ H Ϫ CO Ϫ CH2]
,
ϩ
᝽
᝽
255 (36%) [M Ϫ H Ϫ 2CO]ϩ, 252 (48%), 239 (100%) [M Ϫ
3H Ϫ 2CO Ϫ CH2]ϩ, 226 (66%) [M Ϫ 2H Ϫ 2CO Ϫ 2CH2]ϩ,
215 (52%), 202 (51%), 119 (78%), 113 (82%); ν(CsI)/cmϪ1
2932 (᎐C–H stretching), 1682 (C᎐O stretching); λ(dioxane)/nm
᎐
᎐
322 (ε/dm3 molϪ1 cmϪ1 = 8300), 233 (ε = 16800).
(Found: 312.1148. Calc. for C22H16O2: 312.1150); δH (300
MHz; CD2Cl2) 6.45 (H-4), 6.51 (H-5), 7.11 (H-3) (parts A, B
and X of an ABX-system), 5.71 (H-10), 6.21 (H-8), 6.83
(H-9) (parts A, M and X of an AMX-system), 2.46 (H-11b),
3.32 (H-11a); (J3,4 = 11.0 Hz; J4,5 = 5.5; J8,9 = 11.8; J9,10 = 5.7;
J11a,11b = Ϫ11.3); NOE observed between H-3 and H-10;
δC (75.5 MHz; CD2Cl2) 191.05 (C-7), 141.82, 141.70 (C-1,2,6),
Acknowledgements
The authors thank Professor Dr Emanuel Vogel for suggesting
the project and Dr W. Klug for supplying a quantity of 1,6-
methano[10]annulene.
1
1
140.74, 138.01 (C-9, JC-H = 156.8), 134.63 (C-3, JC-H = 158.6,
2JC-H = 7.2), 131.14 (C-3, JC-H = 162.5, JC-H = 7.2), 129.76
1
2
References
1
1
(C-5, JC-H = 159.2), 128.24 (C-4, JC-H = 158.3), 127.72 (C-10,
1JC-H = 164.5), 33.71 (C-11, JC-H = 136.2); ν(CsI)/cmϪ1 3023,
1
1 I. T. Stone and F. Sondheimer, Tetrahedron Lett., 1978, 19, 4567.
2 R. H. Mitchell, M. Chandry, T. W. Dingle and R. V. Williams,
J. Am. Chem. Soc., 1984, 106, 7776.
3 M. Iyoda, K. Sato and M. Oda, Tetrahedron Lett., 1985, 14,
3829.
4 R. H. Mitchell and J. Zang, Tetrahedron Lett., 1997, 38, 6517.
5 J. Miller and K. Y. Wan, J. Chem. Soc., 1963, 3492.
6 J. Miller, Aromatic Nucleophilic Substitution, Elsevier, Amsterdam,
London and New York, 1968, ch. 1, 4–6.
7 W. S. Rapson, R. G. Shuttleworth and J. N. van Niekerk, J. Chem.
Soc., 1943, 326.
3012 (᎐C–H stretching), 2936 (–C–H stretching), 1631 (C᎐O
᎐
᎐
stretching), 1592, 1536 (C᎐C stretching); m/z (70 eV) 312 (66%)
᎐
[M] ϩ, 311 (16%) [M Ϫ H]ϩ, 297 (10%) [M Ϫ H Ϫ CH2]ϩ,
᝽
295 (9%), 283 (14%) [M Ϫ H Ϫ CO] ϩ, 269 (17%) [M Ϫ
᝽
ϩ
H Ϫ CO Ϫ CH2]
,
252 (23%), 239 (57%) [M Ϫ 3H Ϫ
᝽
2CO Ϫ CH2]ϩ, 43 (100%); λ(CH2Cl2)/nm 515 (ε/dm3 molϪ1
cmϪ1 = 21600), 405 (ε = 5400), 337 (ε = 4700), 286 (ε = 7900),
228 (ε = 25500).
8 (a) G. Wittig and G. Lehmann, Chem. Ber., 1957, 90, 875;
(b) G. Wittig, Q. Rev. Chem. Soc., 1960, 20, 205; (c) G. Wittig and
E. Klar, Liebigs Ann. Chem., 1967, 704, 91; (d) G. Wittig and
K.-D. Rümpler, Liebigs Ann. Chem., 1971, 751, 1; (e) G. Wittig,
S. Fischer and G. Reiff, Liebigs Ann. Chem., 1973, 767, 495.
9 (a) R. B. Kress, E. N. Duesler, M. C. Etter, I. C. Paul and
D. Y. Curtin, J. Am. Chem. Soc., 1980, 102, 7709; (b) K. A. Ken and
J. M. Robertson, J. Chem. Soc. B, 1969, 1146; (c) W. A. C. Brown,
J. Trotter and J. M. Robertson, Proc. Chem. Soc. London, 1961, 115.
10 (a) A. Meyer, K. Schlögl, U. Lerch and E. Vogel, Chem. Ber., 1988,
121, 917; (b) K. R. Wilson and R. E. Pincock, J. Am. Chem. Soc.,
1975, 97, 1474; (c) A. K. Colter and L. M. Clemens, J. Am. Chem.
Soc., 1965, 87, 846; (d) T. Hattori, N. Koike, Y. Oklaishi and
S. Miyano, Tetrahedron Lett., 1966, 37, 2057.
Rearrangement to trans-12a,12b-dihydro-3a(12c),9a(9b)-di-
homoperylene-3,10-dione (V). (E)-syn-2,2Ј-Bi(7H-1,6-methano-
[10]annulenylidene)-7,7Ј-dione (IV) (160 mg, 0.5 mmol) was
dissolved in carbon tetrachloride (100 ml) and heated under
reflux for 2 hours, while exposed to daylight. After evaporation
of the carbon tetrachloride at ambient temperature, the residue
was recrystallized from diethyl ether. The title compound was
obtained in 50% yield as yellow crystals which decomposed at
around 230 ЊC without melting.
(Found: 312.1151. Calc. for C22H16O2: 312.1150); δH (300
MHz; CD2Cl2) 6.08 (H-6,7), 6.12 (H-5,8), 6.79 (H-4,9) (parts A,
M and X of an AMX-system), 6.00 (H-2,11), 6.43 (H-1,12),
11 E. Vogel, K. D. Sturm, A. de F. Dias, J. Lex, H. Schmickler and
F. Wudl, Angew. Chem., Int. Ed. Engl., 1985, 24, 590.
2.91 (H-12a,12b), 2.22 (H-13a,14a), 0.49 (H-13b,14b) (J1,2
=
J. Chem. Soc., Perkin Trans. 1, 2000, 2083–2089
2089