Oxocarbons and related compounds. Part 28. Polycycle-fused dihydrobenzocyclobutenediones and benzocyclobutenediones. Synthesis of cyclobuta[c]- and cyclobuta[a]-phenanthrene-1,2-diones and cyclobuta[a]triphenylene-11,12-dione

Article abstract of DOI:10.1039/a809527b

The Diels-Alder reaction of semisquaric chloride 5 with 1-(alk-1-enyl)naphthalenes, 2-(alk-1-enyl)naphthalenes and 9-vinylphenanthrene is used to prepare dihydrocyclobuta[c]phenanthrene-1,2-diones 8a-c, dihydrocyclobuta[a]phenanthrene-1,2-diones 12a-c, and dihydrocyclobuta[a]triphenylene-11,12-dione 18, respectively. Treatment of the dihydrocyclobutaarenediones with bromine effects aromatization and opens up a route for the synthesis of cyclobuta[c]phenanthrene-1,2-diones 9a-c, cyclobuta[a]phenanthrene-1,2-diones 13a-c and cyclobuta[a]triphenylene-11,12-dione 19. The range of Diels-Alder reactions with semisquaric chloride 5 is extended to the use of 4-(prop-1-enyl)-1,2-dihydronaphthalene 14. Tetrahydrocyclobuta[a]phenanthrene-1,2-dione 15 is obtained in 69% yield, which can be oxidized, stepwise or at once, to give cyclobuta[a]phenanthrene-1,2-dione 13b in good yields.

Full text of DOI:10.1039/a809527b

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1
Oxocarbons and related compounds. Part 28. Polycycle-fused
dihydrobenzocyclobutenediones and benzocyclobutenediones.
Synthesis of cyclobuta[c]- and cyclobuta[a]-phenanthrene-1,2-
diones and cyclobuta[a]triphenylene-11,12-dione
Arthur H. Schmidt,* Gunnar Kircher, Jörg Zylla and Stephan Veit
Abteilung für Organische Chemie und Biochemie, Europa Fachhochschule Fresenius,
Limburger Strasse 2, D-65510 Idstein, Germany
Received (in Cambridge) 7th December 1998, Accepted 14th December 1998
The Diels–Alder reaction of semisquaric chloride 5 with 1-(alk-1-enyl)naphthalenes, 2-(alk-1-enyl)naphthalenes
and 9-vinylphenanthrene is used to prepare dihydrocyclobuta[c]phenanthrene-1,2-diones 8a–c, dihydrocyclobuta-
[
a]phenanthrene-1,2-diones 12a–c, and dihydrocyclobuta[a]triphenylene-11,12-dione 18, respectively. Treatment
of the dihydrocyclobutaarenediones with bromine effects aromatization and opens up a route for the synthesis of
cyclobuta[c]phenanthrene-1,2-diones 9a–c, cyclobuta[a]phenanthrene-1,2-diones 13a–c and cyclobuta[a]triphenyl-
ene-11,12-dione 19. The range of Diels–Alder reactions with semisquaric chloride 5 is extended to the use of 4-(prop-
1
-enyl)-1,2-dihydronaphthalene 14. Tetrahydrocyclobuta[a]phenanthrene-1,2-dione 15 is obtained in 69% yield,
which can be oxidized, stepwise or at once, to give cyclobuta[a]phenanthrene-1,2-dione 13b in good yields.
Introduction
3-chlorocyclobut-3-ene-1,2-dione (semisquaric chloride) in
Diels–Alder reactions for the construction of dihydrobenzo-
cyclobutenediones and benzocyclobutenediones. Application
of this methodology to 5-(alk-1-enyl)benzodioxoles and 1,2-
dialkoxy-4-(alk-1-enyl)benzenes provided a simple and efficient
Benzocyclobutene-1,2-dione (BBD) and substituted benzo-
cyclobutenediones have become useful intermediates in
organic synthesis. They are furthermore used as synthons for
the construction of complex organic compounds. Several effi-
cient methods have been developed for their synthesis and
have given access to their preparation on a gram scale. By con-
trast, only a small number of carbocycle-fused benzocyclo-
butene-1,2-diones (higher analogs of BBD) have been described
so far. At the outset of our work two general routes existed for
2
3
4
5
17
route to cyclobuta[5,6]naphtho[2,3-d][1,3]dioxole-1,2-diones
2,6
1
and 6,7-dialkoxycyclobuta[a]naphthalene-1,2-diones. In the
following we report on the extension of this method for the
preparation of cyclobuta[c]- and cyclobuta[a]-phenanthrene-
1
,2-diones as well as cyclobuta[a]triphenylene-11,12-dione, the
first pentacyclic representative of this type.
7
their preparation: The ‘pyrolytic procedure’ developed by Rees
8
and McOmie which has been used for the preparation of the
9
10
naphtho[a]cyclobutene-1,2-diones 1a and 1b, the naphtho[b]-
Results and discussion
Cyclobuta[c]phenanthrene-1,2-diones
A solution of semisquaric chloride 5 and 1 equiv. of 2-vinyl-
naphthalene 6a in dichloromethane was kept at room temper-
ature for 24 h. During this time the solution took on a dark red
colour. The solvent was removed and the remaining oil was kept
at 70–80 ЊC at reduced pressure until the colour of the highly
viscous oil turned to brown (method A). It was then subjected
to column chromatography. As a result one major product A
and one minor product B were obtained along with some
unreacted starting material 6a. The elemental analysis of A
required the loss of HCl from the educts. This was confirmed by
the mass spectrum which showed a molecular ion at m/z 234.
Since ring closure with semisquaric chloride 5 might take place
in the 1- or 3- position of 2-vinylnaphthalene 6a the two struc-
tures 8a and 8Јa came into question for compound A.
1
The H NMR spectrum provided unambiguous identifi-
cation. The appearance of four doublet signals and two triplet
11
cyclobutene-1,2-dione 2c, and the phenanthro[c]cyclobutene-
1
2
13
1
,2-dione 3, while the naphtho[b]cyclobutene-1,2-diones 2a
14 15
and 2b and phenanthro[l]cyclobutene-1,2-dione 4 were
obtained by Cava’s ‘hydrolysis of annulated tetrahalogenated
cyclobutenes’.
6e
16
Recently we have introduced and established the use of
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414
409

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signals in the aromatic region is in accordance with the aro-
matic proton pattern of 3,4-dihydrocyclobuta[c]phenanthrene-
skeleton. Reaction of semisquaric chloride 5 with 1-vinyl-
naphthalene 10a under the conditions of method A afforded
the 9,10-dihydrocyclobuta[a]phenanthrene-1,2-dione 12a in
29% yield as the only product. 1-(Prop-1-enyl)naphthalene 10b
and 5 were allowed to react according to method B and
afforded 10-methyl-9,10-dihydrocyclobuta[a]phenanthrene-1,2-
dione 12b in slightly higher yield (32%). For reasons of
comparison 1-(isopropenyl)naphthalene 10c and semisquaric
chloride 5 were allowed to react using both methods. Method
A afforded a mixture of the 9,10-dihydrocyclobuta[a]phen-
anthrene-1,2-dione 12c (9%) and the dehydrogenation product
13c (8%). Following method B the same products were obtained
with 15 and 22% yield, respectively. The results are summarized
in Scheme 2. Furthermore it shows that the reaction pathway
1
,2-dione 8a† but not with that of 8Јa. This finding is in
agreement with reports on the reactions of 2-vinylnaphthalene
1
8,19
6
a and 2-(alk-1-enyl)naphthalenes with maleic anhydride
20
and 4-acetoxycyclopent-2-enone which also led to the form-
ation of phenanthrene systems.
On the basis of the structure elucidation of A, compound
B—exhibiting a molecular ion at m/z 232—was readily shown
,
12
to be cyclobuta[c]phenanthrene-1,2-dione 9a (≡3).‡ It is
apparent that 9a results from dehydrogenation of 3,4-dihydro-
cyclobuta[c]phenanthrene-1,2-dione 8a under the experimental
conditions applied.
In extension of the before mentioned results semisquaric
chloride 5 was reacted with 2-(prop-1-enyl)naphthalene 6b and
2
-(isopropenyl)naphthalene 6c without a solvent at elevated
temperature (method B). The expected alkyl-3,4-dihydro-
cyclobuta[c]phenanthrene-1,2-diones 8b,c were obtained,
accompanied by small amounts of the corresponding
dehydrogenated products 9b,c. The results are illustrated and
summarized in Scheme 1.
Scheme 2 Reagents and conditions: i, method A: CH Cl , room temp.
2
2
for 24 h, then heating to ca. 75 ЊC; method B: neat, room temp. to 70 ЊC
within 6 h; ii, CCl , Br , reflux, 3 h.
4
2
leading to 12a–c is completely analogous to that for the
generation of cyclobuta[c]phenanthrene-1,2-diones.
The dihydrocyclobuta[a]phenanthrene-1,2-diones 12a–c were
readily dehydrogenated by treatment with 1.2 equiv. of bromine
and gave the cyclobuta[a]phenanthrene-1,2-diones 13a–c in
good yields.
An alternative route to cyclobuta[a]phenanthrene-1,2-diones
is outlined in Scheme 3. Reaction of semisquaric chloride 5
with 4-(prop-1-enyl)-1,2-dihydronaphthalene 14 led to cis/trans-
10-methyl-2b,3,4-10-tetrahydrocyclobuta[a]phenanthrene-1,2-
dione 15 in good yield. On treatment of 15 with 1.1 equiv. of
bromine regioselective dehydrogenation is observed to give the
3,4-dihydrocyclobuta[a]phenanthrene-1,2-dione 16. This par-
tial dehydrogenation of tetrahydrocyclobuta[a]phenanthrene-
1,2-dione 15 can also be easily accomplished by DDQ.
Subsequent reaction of 16 with one (further) equivalent of
bromine led to 13b.
Scheme 1 Reagents and conditions: i, method A: CH Cl , room temp.
2
2
for 24 h, then heating to ca. 75 ЊC; method B: neat, room temp. to 70 ЊC
within 6 h; ii, CCl , Br , reflux, 3 h.
4
2
According to Scheme 1 the primary cycloadducts from
semisquaric chloride 5 and 2-(alk-1-enyl)naphthalenes 6 suffer
elimination of HCl to give the intermediates 7. The aromatic
naphthalene moiety of 8 is then derived from the rapid double
bond isomerization in the tetracyclic intermediates 7. The 3,4-
dihydrocyclobuta[c]phenanthrene-1,2-diones 8 readily under-
went dehydrogenation. Thus, treatment of 8a–c with 1.2 equiv.
of bromine in boiling tetrachloromethane gave the correspond-
ing cyclobuta[c]phenanthrene-1,2-diones 9a–c in good yields
(
Scheme 1).
Cyclobuta[a]phenanthrene-1,2-diones
Treatment of the tetrahydro compound 15 with 2.1 equiv. of
bromine allowed a one step conversion to the fully aromatized
cyclobuta[a]phenanthrene-1,2-dione 13b. The reaction
sequence 5 ϩ 14→15→13b is experimentally easy to perform
and works with high yields (69 and 91%). Thus it represents
the method of choice for the preparation of cyclobuta[a]-
phenanthrene-1,2-diones.
At the outset of our work cyclobuta[a]phenanthrene-1,2-diones
were unknown. They seemed of special interest since their
four rings are arranged in the same manner as in the steroidal
1
13
†
The H and C chemical shift assignments (see Experimental) were
1 1 1 13
achieved from 2D H– H, H– C connectivities (COSY and HETCOR
experiments).
‡
2
9a prepared by the ‘pyrolytic procedure’ was reported to have mp
Cyclobuta[a]triphenylene-11,12-dione
1
2
77–278 ЊC (decomp.) (ethyl acetate–light petroleum). This value
9
-Vinylphenanthrene 17 reacts analogously, in the diene syn-
21
differs substantially from the mp 248–250 ЊC (toluene) found by us for
an analytically pure sample.
thesis, to vinylnaphthalenes. Its reaction with semisquaric
4
10
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414

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reaction with semisquaric chloride 5. This short methodology
is potentially adaptable to the preparation of even higher
polycycle-fused dihydrobenzocyclobutene-1,2-diones and
benzocyclobutene-1,2-diones, starting from easily available
alken-1-yl) aromatics and (alken-1-yl)dihydro aromatics.
(
Experimental
Melting points were measured in capillary tubes and are
uncorrected. IR spectra were recorded on a Perkin-Elmer 1310
spectrometer, UV spectra on a Perkin-Elmer Lambda 2 spec-
trometer. Mass spectra were determined by electron impact on
a Varian CH 7A spectrometer at an ionizing voltage of 70 eV.
NMR spectra were obtained on a Bruker AM 400 or on a
Bruker AMX 500 spectrometer. GC/MS spectra were recorded
on a Hewlett-Packard 5890, Series II. Injection temperature
was 260 ЊC; column temperature: 60 ЊC at the beginning, gradi-
Ϫ1
ent 10 ЊC min to 250 ЊC, and then 250 ЊC isothermal for 15
min; capillary column DB 624, J&W (30 m × 0.25 mm × 0.25
µm) with He as carrier gas. Elemental analyses were performed
by the Institute of Chemistry, University of Mainz. Analytical
thin layer chromatography was performed on precoated sheets
of silica gel (silica gel 60, F 254, layer thickness 0.2 mm; Riedel
de Haen, Seelze). Column chromatography was performed with
silica gel (silica gel 60, 70–230 mesh; Merck, Darmstadt).
Starting materials
Semisquaric chloride 5 was obtained by reacting semisquaric
16a
Scheme 3
acid with oxalic dichloride. 1-Naphthaldehyde, 2-naphthalde-
hyde, 9-formylphenanthrene, 1-acetylnaphthalene, 2-acetyl-
naphthalene, 2-vinylnaphthalene, 1-tetralone and 1-bromo-
prop-1-ene were obtained from Aldrich.
chloride 5 should, therefore, open up a route to hitherto
unknown pentacyclic diones.
A solution of semisquaric chloride 5 and 9-vinylphenanthrene
1
1
9
7 in dichloromethane was kept at room temperature. After
2 h yellow crystals had deposited. These were identified as
,10-dihydrocyclobuta[a]triphenylene-11,12-dione 18. This
Preparation of the (alk-1-enyl) aromatics 6b,c, 10a–c, 17
Method 1. A solution of the appropriate aldehyde or ketone
3
(
10.00 g) in dry THF (50 cm ) was added slowly to a suspension
finding shows that, in contrast to the formation of dihydrocyclo-
buta[c]- and dihydrocyclobuta[a]-phenanthrene-1,2-diones, the
primary Diels–Alder adduct from 5 and 17 eliminates HCl very
easily, heating being unnecessary for this step. Thus, it may be
concluded that HCl elimination of the primary Diels–Alder
adducts is facilitated by a high degree of annulation. Dehydro-
genation of 18 to cyclobuta[a]triphenylene-11,12-dione 19 was
easily effected, in the usual manner, by treatment with 1.1 equiv.
of bromine.
of 1.5 equiv. of methyltriphenylphosphonium bromide and 1.5
t
3
equiv. of KOBu in dry THF (200 cm ). After magnetic stirring
3
for 30 min at room temperature, water (100 cm ) was added.
The organic layer was separated. The aqueous layer was washed
3
with diethyl ether (3 × 50 cm ). The combined organic layers
3
were washed with water (2 × 100 cm ) and dried (MgSO ). The
4
solvent was then removed under reduced pressure. The residue
3
obtained was extracted with light petroleum (5 × 50 cm ). The
light petroleum was then removed under reduced pressure. The
residue was distilled in vacuo or recrystallized.
Method 2. A solution of 1- or 2-naphthaldehyde (15.00 g, 96
3
mmol) in dry THF (80 cm ) was added slowly at 5 ЊC to a
solution of ethylmagnesium bromide (115 mmol) in dry THF
3
(
80 cm ). The reaction mixture was heated to reflux for 45 min.
3
After cooling to 5 ЊC, water (80 cm ) was added, then HCl
18%, 40 ml). The organic layer was separated. The aqueous
layer was washed with diethyl ether (3 × 50 cm ). The combined
(
3
3
organic layers were washed with water (3 × 50 cm ) and dried
(
MgSO ). The solvent was then removed under reduced pres-
4
sure. The oil obtained was dissolved in a mixture of light
3
petroleum (boiling range 90–110 ЊC)–toluene (1:1) (150 cm ).
To this solution, P O (30 g, 105 mmol) was added and the
4
10
mixture was then heated to reflux for 5 min under vigorous
stirring. The solution was then filtered, and the solvent was
removed under reduced pressure. The residue was subjected to
column chromatography (Al O , neutral, light petroleum as
2
3
Scheme 4 Reagents and conditions: i, CH Cl , room temp. for 12 h;
2
2
eluent). The oil obtained was distilled in vacuo.
ii, AcOH, Br , reflux, 3 h.
2
Preparation of 1,2-dihydro-4-(prop-1-enyl)naphthalene 14
In conclusion, we have described two step syntheses of
cyclobuta[c]- and cyclobuta[a]-phenanthrene-1,2-diones and
cyclobuta[a]triphenylene-11,12-dione based on the Diels–Alder
Method 3. A solution of 1-tetralone (10.00 g, 68 mmol) in dry
3
THF (50 cm ) was added slowly at 5 ЊC to a solution of prop-1-
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414
411

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Table 1 Yields and physical properties of the prepared dienes 6b,c, 10a–c, 14, 17
Diene
Method
Bp or Mp/ЊC
Yield (%)
Purity (%)
88
>98
>98
97
>98
>98
>98
E:Z ratio (%)
6
6
b
c
2
1
1
2
1
3
1
70–73/0.15 mbar
48–50 (MeOH)
75–76/0.1 mbar
110/2 torr
108–110/0.12 mbar
not determined
38 (EtOH–hexane)
41
69
76
28
79
70
66
95:5
—
—
94:6
—
94:6
—
1
1
1
1
1
0a
0b
0c
4
7
enylmagnesium bromide (95 mmol), which was prepared in the
usual manner from 1-bromoprop-1-ene (12.41 g, 103 mmol)
7.38–7.40 (1 H, d, J 8.3), 7.49–7.52 (1 H, t, J 7.5), 7.62–7.66
(1 H, m), 7.78–7.81 (1 H, d, J 8.2), 7.93–7.95 (1 H, d, J 8.3),
8.79–8.81 (1 H, d, J 8.5); δ (100 MHz; CDCl ) 16.57, 28.71,
3
and magnesium turnings (2.31 g, 95 mmol), in THF (80 cm ).
C
3
3
After heating to reflux for 1 h, water (80 cm ) was added, and
37.10, 124.06, 126.54, 126.64, 126.95, 128.17, 128.67, 130.56,
3
then HCl (18%, 40 cm ). The organic layer was separated. The
132.87, 134.61, 137.74, 193.40, 193.52, 194.48, 200.82; m/z 248
3
ϩ
aqueous layer was washed with diethyl ether (3 × 50 cm ). The
(M , 76%), 220 (60), 192 (85), 191 (100), 165 (40).
3
combined organic layers were washed with water (3 × 50 cm )
and dried. Then the solvent was removed under reduced pres-
sure. Column chromatography (silica gel, dichloromethane as
eluent) of the residue afforded 8.15 g (70%) of 14. To avoid any
polymerization the product was not purified by distillation.
4-Methyl-3,4-dihydrocyclobuta[c]phenanthrene-1,2-dione 8c
(Method B). Unreacted 6c: (0.10 g, 6%); 9c: Pale yellow crystals
(0.21 g, 9%), mp 232–233 ЊC; 8b: Yellow crystals from ethyl
acetate (0.87 g, 37%), mp 145–147 ЊC (Found: C, 81.83; H, 4.81.
Ϫ1
C H O requires C, 82.24; H, 4.87%); νmax(KBr)/cm 1770–
1
7
12
2
3
Reaction of semisquaric chloride 5 with (alk-1-enyl)naphthalenes
1745, 1580, 1540 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
mol cm ) 266 (4.27), 230 (4.64), 221 (4.64); δ (400 MHz;
᎐
᎐
Ϫ1
Ϫ1
6
a–c and 10a–c. Preparation of 3,4-dihydrocyclobuta[c]phen-
H
anthrene-1,2-diones 8a–c and 9,10-dihydrocyclobuta[a]phen-
CDCl ) 1.26–1.28 (3 H, d, J 7.2), 3.05–3.10 (1 H, dd, J 3.5,
3
anthrene-1,2-diones 12a–c; general methods
19.0), 3.17–3.19 (1 H, dd, J 7.9, 19.0), 3.43–3.48 (1 H, m), 7.44–
7
7
.46 (1 H, d, J 8.4), 7.51–7.55 (1 H, m), 7.65–7.69 (1 H, m),
.81–7.83 (1 H, d, J 8.2), 7.99–8.01 (1 H, d, J 8.4), 8.86–8.88
Method A. Semisquaric chloride 5 (1.16 g 10 mmol) and the
appropriate (alk-1-enyl)naphthalene 6a, 10a,c (10 mmol) were
dissolved in dichloromethane (20 cm ). After magnetic stir-
ring for 24 h the solvent was removed under reduced pressure.
The obtained red reaction mixture was kept at 70–80 ЊC under
reduced pressure for 45 min. The dark brown, highly viscous oil
was then subjected to column chromatography using dichloro-
methane as eluent. Components are listed in the order of
elution.
3
(1 H, dd, J 0.7, 8.5); δ
C
(100 MHz; CDCl
) 22.84, 28.89, 34.17,
3
1
1
23.20, 126.21, 126.81, 128.19, 128.79, 130.79, 132.82, 135.13,
43.83, 193.20, 193.91, 195.36, 196.92; m/z 248 (M , 77%), 220
ϩ
(
71), 192 (72), 191 (100), 165 (42).
9
,10-Dihydrocyclobuta[a]phenanthrene-1,2-dione
12a
(
Method A). Unreacted 10a: (0.55 g, 18%); 12a: Yellow crystals
from toluene (0.68 g, 52%), mp 221–222 ЊC (Found: C, 81.91;
H, 4.23. C H O requires C, 82.04; H, 4.30%); νmax(KBr)/cm
Ϫ1
Method B. Semisquaric chloride 5 (1.16 g 10 mmol) and the
appropriate (alk-1-enyl)naphthalene 6b,c, 10b,c (10 mmol) were
combined and the solution was stirred magnetically for 6 h.
During this time the reaction mixture was heated from 40 ЊC to
16 10
2
3
1
775, 1760, 1600, 1560 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
᎐ ᎐
Ϫ1 Ϫ1
mol cm ) 285 (4.61), 275 (4.50), 219 (4.52); δ (500 MHz;
H
C D Cl ) 3.20–3.23 (2 H, t, J 8.7), 3.53–3.56 (2 H, t, J 8.7),
2
2
4
7
.55–7.59 (2 H, m), 7.75–7.85 (3 H, m), 8.04–8.05 (1 H, d,
8
0 ЊC. At ca. 70 ЊC HCl was released and removed in vacuo. The
J 7.1); δ (125 MHz, C D Cl ) 22.16, 23.38, 122.83, 123.25,
brown, highly viscous oil was subjected to column chrom-
atography using dichloromethane as eluent. Components are
listed in the order of elution.
C
2
2
4
1
1
1
25.06, 127.86, 128.61, 129.08, 129.65, 131.49, 135.94, 136.51,
ϩ
94.36, 194.65, 195.43, 197.70; m/z 234 (M , 46%), 206 (42),
78 (100), 152 (12).
3
,4-Dihydrocyclobuta[c]phenanthrene-1,2-dione 8a (Method
A). Unreacted 6a: (0.69 g, 44%). 9a: Pale yellow crystals (0.13 g,
%), mp 245–247 ЊC; 8a: yellow crystals from ethyl acetate–
10-Methyl-9,10-dihydrocyclobuta[a]phenanthrene-1,2-dione
12b (Method B). Unreacted 10b: (0.74 g, 44%); 12b: Orange
crystals from ethyl acetate (0.44 g, 32%), mp 175–176 ЊC
8
hexane (0.68 g, 52%), mp 171–172 ЊC (Found: C, 82.14; H, 4.37.
Ϫ1
C H O requires C, 82.04; H, 4.30%); νmax(KBr)/cm 1780,
(Found: C, 82.45; H, 4.87. C17
H
12
O
2
requires C, 82.24; H,
16
10
2
Ϫ1
1
760, 1620, 1595, 1575, 1550 (C᎐O, C᎐C); λmax(MeOH)/nm (log
ε/dm mol cm ) 264 (4.09), 233 (4.55), 219 (4.55); δ (400
MHz; CDCl ) 3.08–3.13 (2 H, m), 3.22–3.27 (2 H, m), 7.38–7.40
1 H, d, J 8.3), 7.49–7.53 (1 H, m), 7.62–7.66 (1 H, m), 7.78–
.80 (1 H, d, J 8.2), 8.78–8.80 (1H, d, J 8.5); δ (100 MHz,
CDCl ) 21.21, 28.26, 124.30, 126.54, 126.71, 126.82, 128.20,
28.72, 130.65, 132.88, 134.64, 137.98, 193.07, 194.49, 194.74,
97.63; m/z 234 (M , 38%), 206 (36), 178 (100), 152 (15).
4.87%); νmax(KBr)/cm 1790–1760, 1595, 1550 (C᎐O, C᎐C);
᎐
᎐
3
Ϫ1
Ϫ1
3
Ϫ1
Ϫ1
λ
max(MeOH)/nm (log ε/dm mol cm ) 286 (4.65), 275 (4.54),
H
219 (4.56); δ (400 MHz; CDCl ) 1.43–1.44 (3 H, d, J 7.2), 3.10–
3
H
3
(
3.17 (1 H, dd, J 9.5, 17.1), 3.42–3.51 (1 H, m), 3.65–3.72 (1 H,
dd, J 8.5, 17.1), 7.50–7.58 (2 H, m), 7.71–7.84 (3 H, m), 8.06–
7
C
8.10 (1 H, m); δ (100 MHz; CDCl ) 16.90, 28.66, 31.38, 121.89,
3
C
3
1
1
122.09, 124.27, 126.78, 127.51, 127.95, 128.63, 130.80, 134.94,
ϩ
ϩ
135.61, 192.16, 193.97, 194.39, 200.04; m/z 248 (M , 53%), 220
(
40), 192 (84), 191 (100), 165 (39).
3
-Methyl-3,4-dihydrocyclobuta[c]phenanthrene-1,2-dione 8b
(
Method B). Unreacted 6b: (0.72 g, 43%); 9b: Pale yellow crys-
9-Methyl-9,10-dihydrocyclobuta[a]phenanthrene-1,2-dione
tals (0.07 g, 5%), mp 255–257 ЊC. 8b: Yellow crystals from ethyl
acetate (0.94 g, 66%), mp 157–158 ЊC (Found: C, 82.20; H, 4.90.
12c (Method A). Unreacted 10c: (1.03 g, 61%); 13c: Pale yellow
crystals (0.08 g, 8%), mp 261–262 ЊC; 12c: Orange crystals from
ethyl acetate (0.09 g, 9%), mp 175–176 ЊC (Found: C, 82.11;
Ϫ1
C H O requires C, 82.24; H, 4.87%); νmax(KBr)/cm 1760–
1
7
12
2
3
Ϫ1
1
740, 1580, 1565, 1535 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
mol cm ) 266 (4.22), 232 (4.62), 222 (4.62); δ (400 MHz;
H, 4.79. C H O requires C, 82.24; H, 4.87%); νmax(KBr)/cm 3
᎐
᎐
17 12
2
Ϫ1
Ϫ1
1790–1760, 1600, 1550 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
H
Ϫ1
Ϫ1
CDCl ) 1.42–1.44 (3 H, d, J 7.1), 2.92–2.99 (1 H, dd, J 10.0,
mol cm ) 285 (4.64), 275 (4.53), 219 (4.53); δ (400 MHz;
3
H
J 16.5), 3.17–3.19 (1 H, dd, J 8.0, 16.5), 3.43–3.42 (1 H, m),
CDCl ) 1.24–1.25 (3 H, d, J 7.3), 3.22–3.24 (2 H, m), 4.16–4.20
3
4
12
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414

View Article Online
(
(
1
1
1 H, m), 7.59–7.63 (2 H, m), 7.82–7.91 (3 H, m), 8.12–8.15
82.72; H, 4.01. C H O requires C, 82.91; H, 4.09%); νmax-
17 10 2
Ϫ1
1 H, m); δ (100 MHz; CDCl ) 22.56, 29.09, 29.68, 121.64,
(KBr)/cm 1780–1750, 1585, 1550 (C᎐O, C᎐C); λmax(MeOH)/
3 Ϫ1 Ϫ1
C
3
23.17, 124.51, 127.58, 128.32, 128.49, 129.54, 130.49, 136.67,
nm (log ε/dm mol cm ) 304 (4.60), 295 (4.60), 262 (4.56), 207
(4.43); δ (500 MHz; C D Cl ) 3.25 (3 H, s), 7.74–7.77 (2 H, m),
ϩ
41.46, 193.25, 194.29, 195.95, 196.53; m/z 248 (M , 76%), 220
H
2
2
4
(
(
74), 205 (88), 192 (51), 43 (100). (Method B): Unreacted 10c:
0.58 g, 35%); 13c: (0.36 g, 22%); 12c: (0.25 g, 15%).
7.94 (1 H, s), 8.02–8.07 (2 H, m), 8.32–8.34 (1 H, d, J 8.6), 8.88–
8.90 (1 H, m); δ (125 MHz; C D Cl ) 29.33, 122.35, 123.63,
C
2
2
4
1
27.09, 128.04, 128.66, 129.05, 130.36, 131.01, 132.75, 134.39,
ϩ
Preparation of cyclobuta[c]phenanthrene-1,2-diones 9a–c and
cyclobuta[a]phenanthrene-1,2-diones 13a–c; general method
135.98, 147.63, 172.84, 172.88, 194.53, 194.61; m/z 4246 (M ,
31%), 218 (79), 190 (100), 163 (21), 95 (27).
To a boiling solution of a dihydrocyclobutaphenanthrene-1,2-
3
cis/trans-10-Methyl-2b,3,4,10-tetrahydrocyclobuta[a]phen-
anthrene-1,2-dione 15
dione (0.3 g) in tetrachloromethane (25 cm ) was added a solu-
3
tion of bromine (1.1 equiv.) in the same solvent (10 cm ) in one
portion. It was heated to reflux until no further HBr was
evolved (ca. 3 h). Within this period of time the product precipi-
tated. After cooling to Ϫ15 ЊC the product was collected by
filtration and recrystallized.
A solution of 1,2-dihydro-4-(prop-1-enyl)naphthalene 14 (3.40
g, 20 mmol) in dichloromethane (30 cm ) was combined with
3
semisquaric chloride 5 (2.32 g, 20 mmol) dissolved in dichloro-
3
methane (10 cm ). The resulting mixture heated up and took on
an intense dark red colour. It was stirred magnetically at room
temperature for 30 min. The solvent was then removed under
reduced pressure and the red oil left behind was kept at 70–
80 ЊC in vacuo for 30 min. The resulting brown, highly viscous
oil was crystallized twice from ethanol to give 15. Orange crys-
tals from ethanol (3.46 g, 69%), mp 128 ЊC (Found: C, 81.64;
Cyclobuta[c]phenanthrene-1,2-dione 9a. Pale yellow crystals
from toluene (0.27 g, 91%), mp 248–250 ЊC (Found: C, 82.51;
Ϫ1
H, 3.43. C H O requires C, 82.75; H, 3.47%); νmax(KBr)/cm 3
16
8
2
1
765–1740, 1590, 1570 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
᎐ ᎐
Ϫ1 Ϫ1
mol cm ) 306 (4.56), 224 (4.80); δ [500 MHz; (CD ) SO]
H
3 2
Ϫ1
7
8
9
1
1
3
.85–7.87 (1 H, m), 7.90–7.93 (1 H, m), 8.15–8.18 (2 H, m),
.21–8.24 (1 H, m), 8.27–8.30 (1 H, m), 8.49–8.52 (1 H, m),
.40–9.42 (1 H, m); δ [125 MHz; (CD ) SO] 117.94, 125.57,
H, 5.51. C H O requires C, 81.58; H, 5.64%); νmax(KBr)/cm 3
17
14
2
1790–1760, 1595, 1550 (C᎐O, C᎐C); λ (MeOH)/nm (log ε/dm
᎐
᎐
max
1
Ϫ1
Ϫ1
13
C
3
2
mol cm ) 214 (4.45); signals in the H and C NMR spectra
26.12, 126.79, 127.86, 128.01, 128.51, 128.71, 132.31, 132.34,
appeared in pairs, indicating a mixture of isomers; m/z 250
ϩ
ϩ
35.13, 138.07, 172.49, 173.03, 192.52, 192.71; m/z 232 (M ,
(M , 52%), 222 (20), 207 (25), 194 (30), 179 (100), 165 (42).
5%), 204 (57), 176 (100), 119 (11), 88 (19).
1
0-Methylcyclobuta[a]phenanthrene-1,2-dione 13b from 15
3
-Methylcyclobuta[c]phenanthrene-1,2-dione 9b. Pale yellow
The dehydrogenation was carried out in analogy to the prepar-
ation of cyclobutaphenanthrenediones from dihydrocyclobuta-
phenanthrenediones (see general procedure), with the exception
that 2.2 equiv. of bromine were used. 13b was obtained in 85%
yield.
crystals from toluene (0.29 g, 97%), mp 255–257 ЊC (Found:
C, 82.63; H, 3.97. C H O requires C, 82.91; H, 4.09%);
17
10
2
Ϫ1
νmax(KBr)/cm 1750, 1595 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/
3
Ϫ1
Ϫ1
dm mol cm ) 309 (4.67), 226 (4.91); δ (500 MHz; C D Cl )
H
2
2
4
2
8
.69 (3 H, s), 7.70–7.85 (4 H, m), 7.91–7.93 (1 H, d, J 7.9), 8.00–
.02 (1 H, d, J 8.7), 9.29–9.31 (1 H, d, J 8.3); δ (125 MHz;
C D Cl ) 18.25, 125.53, 126.37, 128.24, 128.89, 129.27, 129.54,
2
C
10-Methyl-3,4-dihydrocyclobuta[a]phenanthrene-1,2-dione 16
2
4
1
1
30.09, 131.68, 133.06, 133.89, 136.75, 138.33, 174.06, 174.08,
94.28, 194.67; m/z 246 (M , 46%), 218 (84), 190 (99), 189
By dehydrogenation with DDQ.
tetrahydrocyclobuta[a]phenanthrene-1,2-dione 15 (0.6 g, 2.4
mmol) and DDQ (0.6 g, 2.6 mmol) in dioxane (50 cm ) was
A solution of the
ϩ
(
100), 95 (53).
3
heated to reflux for 3 h under magnetic stirring. The solution
was then cooled to room temperature and filtered from precipi-
tated hydroquinone. The solvent was removed under reduced
pressure to leave 16. Orange crystals from ethyl acetate (0.38 g,
4
-Methylcyclobuta[c]phenanthrene-1,2-dione 9c. Pale yellow
crystals from toluene (0.24 g, 81%), mp 233–234 ЊC (Found:
C, 82.99; H, 4.16. C H O requires C, 82.91; H, 4.09%);
νmax(KBr)/cm 1750, 1595 (C᎐O, C᎐C); λmax(MeOH)/nm (log
ε/dm mol cm ) 306 (4.54), 227 (4.74); m/z 246 (M , 46%),
17
10
2
Ϫ1
6
4%), mp 185–186 ЊC (Found: C, 82.19; H, 4.88. C17H O2
12
3
Ϫ1
Ϫ1
ϩ
Ϫ1
requires C, 82.24; H, 4.87%); νmax(KBr)/cm 1770–1750, 1610,
2
18 (84), 190 (99), 189 (100), 95 (53).
3
Ϫ1
1
600, 1550 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm mol
᎐ ᎐
Ϫ1
cm ) 284 (4.49), 238 (4.25), 207 (4.26); δ (400 MHz; CDCl )
H
3
Cyclobuta[a]phenanthrene-1,2-dione 13a. Pale yellow crystals
from xylene (0.20 g, 67%), mp 286–287 ЊC (Found: C, 82.38; H,
1
7
.27 (3 H, s), 2.89–2.94 (2 H, t, J 6.9), 3.13–3.16 (2 H, t), 7.28–
.30 (1 H, m), 7.33–7.36 (2 H, m), 7.79–7.81 (1 H, m), 7.83 (1 H,
Ϫ1
3
1
.30. C H O requires C, 82.75; H, 3.47%); νmax(KBr)/cm 3
16
8
2
s); δ (100 MHz; CDCl ) 18.01, 24.06, 27.63, 125.28, 127.53,
C
3
770–1750, 1580 (C᎐O, C᎐C); λmax(MeOH)/nm (log ε/dm
᎐
᎐
128.81, 130.07, 130.35, 131.81, 131.99, 133.66, 138.25, 141.69,
Ϫ1
Ϫ1
ϩ
mol cm ) 297 (4.56), 262 (4.56), 207 (4.40); m/z 232 (M ,
0%), 204 (50), 176 (100), 88 (25).
ϩ
1
1
70.86, 171.10, 194.66, 195.68; m/z 248 (M , 22%), 220 (100),
92 (80), 191 (42), 165 (18).
3
1
0-Methylcyclobuta[a]phenanthrene-1,2-dione 13b. Pale yel-
By dehydrogenation of 15 with bromine. To a solution of the
low crystals from toluene (0.22 g, 74%), mp 282–283 ЊC (Found:
C, 82.50; H, 3.96. C H O requires C, 82.91; H, 4.09%);
νmax(KBr)/cm 1760–1745, 1605, 1590 (C᎐O, C᎐C); λmax-
MeOH)/nm (log ε/dm mol cm ) 300 (4.55), 266 (4.59), 207
4.37); δ (500 MHz; C D Cl ) 2.76 (3 H, s), 7.73–7.74 (2 H, m),
.96–7.98 (2 H, m), 8.20–8.21 (1 H, m), 8.64–8.66 (2 H, m);
δ (125 MHz; C D Cl ) 18.82, 123.00, 123.78, 124.46, 128.76,
29.50, 129.75, 129.96, 131.42, 131.67, 131.77, 134.70, 134.74,
74.40 (2 C), 195.01, 195.16; m/z 246 (M , 39%), 218 (74), 190
tetrahydrocyclobuta[a]phenanthrene-1,2-dione 15 (0.5 g, 2
17
10
2
3
mmol) in tetrachloromethane (30 cm ) was added bromine
Ϫ1
3
(
0.35 g, 2.2 mmol) in tetrachloromethane (10 cm ) within 10
3
Ϫ1
Ϫ1
(
(
7
min at room temperature. The reaction solution was stirred
magnetically at room temperature until the brown colour faded
and HBr started to evolve. It was then heated to reflux for 3 h
and the solvent removed under reduced pressure. The solid
obtained was recrystallized from ethyl acetate to give 16 as
orange crystals (0.26 g, 52%).
H
2
2
4
C
2
2
4
1
1
(
ϩ
100), 95 (33).
1
0-Methylcyclobuta[a]phenanthrene-1,2-dione 13b from 16
9
-Methylcyclobuta[a]phenanthrene-1,2-dione 13c. Pale yellow
crystals from toluene (0.24 g, 81%), mp 261–262 ЊC (Found: C,
The reaction was carried out as described for the preparation
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414
413

View Article Online
of cyclobutaphenanthrenediones from dihydrocyclobutaphen-
anthrenediones to give 13b as pale yellow crystals (0.23 g, 77%).
1972, 94, 7087; (c) J. W. Barton, M C. Goodland, K. J. Gould,
J. Hadley and J. F. W. McOmie, Tetrahedron, 1978, 34, 495; J. W.
Barton, M. C. Goodland, K. J. Gould, J. F. W. McOmie, W. R.
Mound and S. A. Saleh, Tetrahedron, 1979, 35, 241.
9
,10-Dihydrocyclobuta[a]triphenylene-11,12-dione 18
4
(a) H. A. Staab and J. Ipaktschi, Tetrahedron Lett., 1966, 583; (b)
H. A. Staab and J. Ipaktschi, Chem. Ber., 1968, 101, 1457; (c) M. E.
Jung and J. A. Lowe, J. Org. Chem., 1977, 42, 2371; (d) L. A.
Spangler and J. S. Swenton, J. Org. Chem., 1984, 49, 1800 and
references cited therein; (e) C. F. Wilcox, Jr. and E. N. Farley, J. Org.
Chem., 1985, 50, 351; ( f ) L. S. Liebeskind, S. L. Baysdon, M. S.
South, S. Iyer and J. P. Leeds, Tetrahedron, 1985, 41, 5839 and
references cited therein; (g) L. A. Spangler and J. S. Swenton,
J. Chem. Soc., Chem. Commun., 1986, 828; (h) L. S. Liebeskind,
S. Iyer and C. F. Jewell, Jr., J. Org. Chem., 1986, 51, 3065; (i) S. T.
Petri, L. D. Foland, O. H. W. Decker and H. W. Moore, J. Org.
Chem., 1986, 51, 3067; (j) O. H. W. Decker and H. W. Moore,
J. Org. Chem., 1987, 52, 1174; (k) L. S. Liebeskind, R. Chidam-
baram, D. Mitchell and B. S. Foster, Pure Appl. Chem., 1988, 60, 27;
A solution of 9-vinylphenanthrene 17 (1.53 g, 7.5 mmol) and
semisquaric chloride 5 (0.87 g, 7.5 mmol) in dichloromethane
3
(
25 cm ) was stirred magnetically for 12 h at room temperature.
During this time yellow crystals precipitated from the solution.
After cooling to Ϫ15 ЊC the crystals were collected by filtration
to give 18. Orange crystals from THF (0.51 g, 24%), mp 220–
2
21 ЊC (Found: C, 84.46; H, 4.31. C H O requires C, 84.49;
20 12 2
Ϫ1
H, 4.25%); νmax(KBr)/cm 1780, 1750, 1590, 1560 (C᎐O, C᎐C);
3
Ϫ1
Ϫ1
λmax(MeOH)/nm (log ε/dm mol cm ) 256 (4.68), 213 (4.60);
δ (500 MHz; C D Cl ) 3.17–3.21 (2 H, t, J 8.9), 3.53–3.56 (2H,
H
2
2
4
t, J 8.9), 7.64–7.74 (4 H, m), 8.11–8.13 (1 H, d, J 8.3), 8.60–8.62
1 H, d, J 8.2), 8.66–8.68 (1 H, d, J 8.3), 8.75–8.77 (1 H, d,
J 8.0); δ (125 MHz; C D Cl ) 21.40, 24.48, 123.02, 123.88,
(
l) L. D. Foland, O. H. W. Decker and H. W. Moore, J. Am. Chem.
(
Soc., 1989, 111, 989; (m) L. S. Liebeskind, Tetrahedron, 1989, 44,
C
2
2
4
3
1
053; (n) D. Mitchell and L. S. Liebeskind, J. Am. Chem. Soc., 1990,
12, 291.
1
1
24.30, 126.14, 127.43, 127.98, 128.05, 128.19, 128.59, 129.77,
29.90, 129.99, 133.09, 137.00, 193.26, 194.80, 195.91, 197.82;
5
6
For a review, see: H. W. Moore and B. R. Yerxa, Chemtracts: Org.
Chem., 1992, 5, 273.
ϩ
m/z 284 (M , 60%), 256 (41), 228 (100), 226 (87), 224 (23).
Newer methods not mentioned in ref. 2: (a) G. Seitz, R. Sutrisno and
T. Kämpchen, Chem.-Ztg., 1980, 104, 12; (b) M. S. South and L. S.
Liebeskind, J. Org. Chem., 1982, 47, 3815; (c) D. J. Burton and B. A.
Link, J. Fluorine Chem., 1983, 22, 397; (d) L. S. Liebeskind, L. J.
Lescosky and C. M. McSwain, Jr., J. Org. Chem., 1989, 54, 1435; (e)
A. H. Schmidt and Ch. Künz, Synthesis, 1991, 78; ( f ) J. P. Edwards,
D. J. Krysan and L. S. Liebeskind, J. Org. Chem., 1993, 58, 3942;
Cyclobuta[a]triphenylene-11,12-dione 19
The dehydrogenation of 18 was performed in analogy to the
preparation of cyclobutaphenanthrenediones (see general pro-
cedure), with the exception that acetic acid was used as the
solvent to give 19. Yellow crystals from xylene (0.28 g, 94%),
mp 278–279 ЊC (Found: C, 85.10; H, 3.68. C H O requires C,
(
g) T. Hosoya, T. Hasegawa, Y. Kuriyama, T. Matsumoto and
2
0
12
2
K. Suzuki, Synlett, 1995, 177.
Ϫ1
8
5.09; H, 3.57%); νmax(KBr)/cm 1790–1750, 1610, 1590 (C᎐O,
7 D. L. Forster, T. L. Gilchrist, C. W. Rees and E. Stanton, J. Chem.
Soc., Chem. Commun., 1971, 695.
8 J. F. W. McOmie and D. H. Perry, J. Chem. Soc., Chem. Commun.,
3 Ϫ1 Ϫ1
C᎐C); λ (MeOH)/nm (log ε/dm mol cm ) 304 (4.49), 272
᎐
max
ϩ
(
(
4.46), 240 (4.49); m/z 282 (M , 34%), 254 (55), 226 (100), 145
1
973, 248.
25), 119 (37).
9
K. J. Gould, N. P. Hacker, J. F. McOmie and D. H. Perry, J. Chem.
Soc., Perkin Trans. 1, 1980, 1834.
Acknowledgements
The authors gratefully acknowledge financial support for this
work from the Deutsche Forschungsgemeinschaft (DFG),
Bonn-Bad Godesberg (Grant: Schm 309-6/2 and Schm 309-6/
10 R. F. C. Brown, K. J. Coulston, F. W. Eastwood and S. Saminathan,
Aust. J. Chem., 1987, 40, 107.
11 R. F. C. Brown, N. R. Browne, K. J. Coulston and F. W. Eastwood,
Aust. J. Chem., 1990, 43, 1935.
1
2 M. Adeney, R. F. C. Brown, K. J. Coulston, F. W. Eastwood and
I. W. James, Aust. J. Chem., 1991, 44, 967.
3
). They are also grateful to Professor Dr H. Meier, Universität
1
1
1
3 A. C. Hsu and M. P. Cava, J. Org. Chem., 1979, 44, 3790.
4 M. P. Cava and B. Hwang, Tetrahedron Lett., 1965, 2297.
5 N. P. Hacker, J. F. W. McOmie, J. Meunier-Piret and M.
VanMeerssche, J. Chem. Soc., Perkin Trans. 1, 1982, 19.
Mainz, for permission to record NMR and mass spectra, to
H. Kolshorn, Universität Mainz, for carrying out 2D NMR
experiments, to H. Reisch, Max-Planck Institut für Polymer-
forschung, Mainz, for recording the NMR spectra of several
compounds on a Bruker AMX 500 spectrometer, and to Dr
G. Penzlin, Beilstein-Institut, Frankfurt am Main, for his
advice on nomenclature.
16 (a) A. H. Schmidt, C. Künz, M. Malmbak and J. Zylla, Synthesis,
994, 422; (b) A. H. Schmidt, K. O. Lechler, T. Pretz and I. Franz,
1
J. Chem. Soc., Perkin Trans. 1, 1996, 497.
1
7 A. H. Schmidt, G. Kircher, C. Künz, S. Wahl and M. W. Hendriok,
J. Org. Chem., 1995, 60, 3890.
1
1
8 A. Cohen and F. L. Warren, J. Chem. Soc., 1937, 1315.
9 (a) F. Bergmann and A. Weizmann, J. Org. Chem., 1944, 9, 352; (b)
F. Bergmann and A. Weizmann, J. Org. Chem., 1946, 11, 592.
References
1
Part 27, A. H. Schmidt, G. Kircher, M. Spring, M. W. Hendriok and
C. Künz, J. Prakt. Chem./Chem.-Ztg., 1997, 339, 564.
20 L. Minuti and A. Taticchi, Tetrahedron, 1994, 50, 10359.
21 E. Bergmann and F. Bergmann, J. Am. Chem. Soc., 1937, 57, 1443.
2
3
For a review, see: A. H. Schmidt and W. Ried, Synthesis, 1978, 869.
(a) M. P. Cava, R. J. Pohl and M. J. Mitchell, J. Am. Chem. Soc.,
1963, 85, 2080; M. P. Cava and R. P. Stein, J. Org. Chem., 1966, 31,
866; (b) P. J. Garratt and K. P. C. Volhardt, J. Am. Chem. Soc.,
1
Paper 8/09527B
4
14
J. Chem. Soc., Perkin Trans. 1, 1999, 409–414