(
(
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