3
(
(
100 cm ), the organic phase separated, washed with water
8 and 1), 8.03 (1 H, d, J 8), 8.11 (1 H, d, J 8), 8.24 (1 H, d, J 8)
+
3
3 × 50 cm ), saturated aqueous sodium hydrogen carbonate
and 8.54 (1 H, dd, J 8 and 1); m/z 304 (M , 100%), 276 (67,
3
+
+
solution (2 × 50 cm ), dried with magnesium sulfate, filtered,
and the solvents removed under reduced pressure to give the
ester 23a as a white powder (2.4 g, 31%); mp 108–110 ЊC (from
ethanol, lit., 113–114 ЊC) (Found: C, 78.9; H, 6.15. C H O
requires C, 78.9; H, 6.1%); λ (EtOH)/nm 232 (ε/dm mol
M Ϫ CO), 274 (31, M Ϫ CH O), 138 (45) and 137 (27).
2
7,8-Dioxo-7H,8H-dibenzo[de,hi]naphthacene 20. Improved
procedure
1
4
2
3
8
26
4
Ϫ1
A mixture of the acid 23b (19 g, 51 mmol) and phosphorus
max
Ϫ1
Ϫ1
3
cm 86 500) and 284 (31 000); νmax/cm (film) 1770 (C᎐O) and
pentoxide (18.5 g) in nitrobenzene (100 cm ) was stirred at room
᎐
3
1
7
610 (C᎐C); δ (CDCl ) 0.90 (6 H, t, J 7.1, CH ), 3.9 (4 H, q, J
temp. for 3 d under argon. Water (100 cm ) was added dropwise
᎐
H
3
3
.1, CH ), 4.26 (1 H, d, J 12.0, CHCH), 6.52 (1 H, d, J 12.0,
and the nitrobenzene was removed by steam distillation. The
resulting black solid was filtered off, dried and subjected to
chromatography on alumina eluting first with light petroleum
(bp 40–60 ЊC) then 1:1 light petroleum–dichloromethane, 1:3
light petroleum–dichloromethane, and finally 1:10 light
petroleum–dichloromethane until the eluent was colourless.
Then 1:339 methanol–dichloromethane gave 7,8-dioxo-7H,8H-
dibenzo[de,hi]naphthacene 20 as an acid-sensitive yellow solid
2
CHCH), 7.5 (8 H, m), 7.75 (2 H, d, J 7.1), 7.85 (2 H, d, J 7.5)
and 8.42 (2 H, d, J 7.5); δ (CDCl ) 13.2 (CH ), 40.1 (CH), 58.3
CH), 61.1 (CH ), 123.2, 124.6, 124.9, 125.3, 126.1, 127.4,
C
3
3
(
1
2
28.5, 131.2, 133.7, 137.4 and 167.7 (C᎐O).
᎐
5
Bis(1-naphthyl)methylmalonic acid 23b
A mixture of the foregoing ester 23a (29.1 g, 68 mmol) and
potassium hydroxide (112 g) in ethanol (750 cm ) was refluxed
for 3 h. The ethanol was distilled off and water added. This was
3
3
Ϫ1
Ϫ1
(90 mg, 5%); λmax(EtOH)/nm 205 (ε/dm mol cm 27 500),
Ϫ1
244 (28 600), 362 (8530) and 410 (15 000); νmax/cm (Nujol)
3
also distilled off, a second volume of water (250 cm ) added,
1670 (C᎐O) and 1570 (C᎐C); δ (CDCl ) 7.75 (2 H, t, J 7.8), 7.82
H
3
and the pH adjusted to pH 1 by addition of 36% HCl. The
mixture was cooled to room temp. and filtered. The residue was
recrystallised from ethanol to give the acid 23b as colourless
(2 H, t, J 7.7), 8.18 (2 H, d, J 7.8), 8.23 (2 H, d, J 7.7), 8.25 (2 H,
d, J 7.7) and 8.72 (2 H, d, J 7.8); δ (CDCl ) 125.4, 125.9, 127.6,
128.3, 129.9, 130.3, 131.3, 132.3, 133.3, 134.4, 135.3, 135.4 and
C
3
5
needles (19 g, 75%); mp 190–192 ЊC (lit., 196 ЊC) (Found: C,
181.7 (C᎐O).
7
8.1; H, 5.0. C H O requires C, 78.1; H, 4.9%); λmax(EtOH)/
24 18 4
3 Ϫ1 Ϫ1 Ϫ1
18
nm 246 (ε/dm mol cm 75 100) and 280 (36 600); νmax/cm
4,6-Dichloro-1,3-dimethylbenzene 28
(
3
7
film) 1710 (C᎐O) and 1610 (C᎐C); δ (CDCl ) 3.57 (1 H, d, J
.6, CHCH), 6.52 (1 H, d, J 3.6, CHCH), 7.33 (2 H, t, J 7.6),
.45 (6 H, m), 7.73 (2 H, d, J 7.9), 7.90 (2 H, d, J 7.9) and 7.98 (2
Chlorine gas was bubbled for 30 h through a well-stirred mix-
ture of 1,3-dimethylbenzene (240.5 g, 2.45 mol) and ferric
chloride hexahydrate (18 g, 0.066 mol) maintained at 0–5 ЊC by
external ice–salt bath cooling. When ca. 1 mol of chlorine had
been absorbed (by mass) the mixture was washed with 2
᎐
᎐
H
3
H, d, J 7.6); δ (CDCl ) 42.3 (CH), 53.4 (CH), 123.3, 125.2,
1
C
3
25.2, 126.1, 126.6, 126.8, 128.8, 131.1, 135.3, 139.5 and 173.5
᎐
3
3
(C᎐O).
hydrochloric acid (2 × 500 cm ), water (2 × 500 cm ), dried
CaCl ) and filtered. The filtrate was distilled under reduced
(
2
7
,8-Dioxo-7H,8H-dibenzo[de,hi]naphthacene 20. Attempted
pressure. The fraction boiling at 85–100 ЊC and 0.5 mmHg was
refrigerated at Ϫ4 ЊC for 3 d and filtered to give colourless
needles of 4,6-dichloro-1,3-dimethylbenzene 28 (60 g, 10%); mp
5
preparation by the Clar procedure
Phosphorus pentoxide (2.4 g) was added to the acid 23b (0.6 g,
1
3
18
Ϫ1
.6 mmol) in nitrobenzene (8 cm ) at 155 ЊC under argon. After
70 ЊC (from ethanol, lit., 68.5 ЊC); νmax/cm (Nujol) 1560
(C᎐C); δ (CDCl ) 2.25 (6 H, s, CH ), 7.0 (1 H, s) and 7.25 (1 H,
a further 15 min at 155 ЊC the mixture was cooled to room
temp., water was added dropwise and the nitrobenzene was
removed by steam distillation. The residue was dissolved in
dichloromethane and the dichloromethane solution was
washed with water, aqueous ammonia and water, dried with
magnesium sulfate, filtered and the solvent removed under
reduced pressure. The resulting red–brown gum (520 mg) was
subjected to chromatography on silica eluting first with 9:1
light petroleum (bp 40–60 ЊC)–diethyl ether, then 1:1 light
petroleum–dichloromethane, dichloromethane and finally
᎐
H
3
3
s); δ (CDCl ) 19.3 (CH ), 128.7, 131.8, 132.6 and 134.2.
C
3
3
2
9
4,6-Dibromo-1,3-dimethylbenzene
Iodine (0.5 g) was added over 30 min to a vigorously shaken
mixture of 1,3-dimethylbenzene (26 g, 0.245 mol) and bromine
(43.4 g, 0.27 mol). This mixture was shaken for a further 3 h,
3
and then shaken with 2 sodium hydroxide (200 cm ) for 10
min. The resulting suspension was filtered, the residue washed
with water, and recrystallised from ethanol to give 4,6-dibromo-
2
9
9
7:3 dichloromethane–methanol to give 2,3-dihydro-3-(1-
1,3-dimethylbenzene (14.5 g, 22%); mp 67–69 ЊC (lit., 69 ЊC)
naphthyl)phenalen-1-one 25 as a white crystalline solid (32 mg,
(Found: C, 36.5; H, 3.0; Br, 60.35. C H Br requires C, 36.4; H,
8
8
2
1
7
+
Ϫ1
7
%); mp 75–76 ЊC (lit., 75–76 ЊC) (Found: M , 308.1201.
3.0; Br, 60.6%); νmax/cm (Nujol) 1560 (C᎐C); δ (CDCl ) 2.25
H 3
Ϫ1
C H O requires 308.1201); νmax/cm (CHCl ) 1705 (C᎐O),
(6 H, s, CH ), 7.0 (1 H, s) and 7.6 (1 H, s); δ (CDCl ) 22.0
3 C 3
2
3
16
3
1
590 and 1625 (C᎐C); δ (CDCl ) 2.70 (1 H, dd, J 18 and 1.5,
(CH ), 122.5, 132.5, 135.0 and 136.9.
᎐
H
3
3
CH ), 3.60 (1 H, dd, J 18 and 8, CH ), 5.82 (1 H, dd, J 8 and 1.5,
2
2
CH), 6.70 (1 H, d, J 7), 7.22 (1 H, d, J 7), 7.3–8.2 (10 H, m) and
4,6-Dichlorobenzene-1,3-dicarboxylic acid 29
A vigorously stirred solution of 4,6-dichloro-1,3-dimethyl-
benzene 28 (50 g, 0.29 mol) in nitrobenzene (50 cm ) in an
apparatus fitted with a Dean and Stark separator was heated to
+
8
.47 (1 H, dd, J 7 and 1); m/z 308 (M , 100%), 279 (27,
+
+
3
M Ϫ CHO), 265 (23, M Ϫ C H O), 155 (25), 153 (22,
2
2
3
+
79 Ϫ C H ), 152 (49, 279 Ϫ C H ), 127 (27, C H ) and 126
1
0
6
10
7
10
7
+
3
(21, C H ): 3-(1-naphthyl)phenalen-1-one 26 as a white crys-
150 ЊC. Concentrated nitric acid (d = 1.4, 25 cm ) was added
1
0
6
1
7
talline solid (35 mg, 7%); mp 189–190 ЊC (lit., 189–190 ЊC)
dropwise over 30 h at such a rate that the temperature of the
reaction mixture neither fell below 150 ЊC nor rose above
180 ЊC. Over-rapid addition of the acid resulted in a highly
exothermic process. The reaction was complete at the point at
which (at 160 ЊC) a thick emulsion was produced. The mixture
+
Ϫ1
(Found: M , 306.1035. C H O requires 306.1044); νmax/cm
23 14
(
CHCl ) 1640 (C᎐O), 1610 and 1570 (C᎐C); δ (CDCl ) 6.82 (1
3
᎐
᎐
H
3
H, s, vinyl CH), 7.2–8.1 (11 H, m), 8.24 (1 H, dd, J 8 and 1) and
+
+
8
2
.76 (1 H, dd, J 7 and 1); m/z 306 (M , 28%), 305 (28, M Ϫ H),
+ + +
3
89 (56, M Ϫ OH), 277 (21, M Ϫ CHO), 276 (67, M Ϫ
was cooled to room temp. Carbon tetrachloride (150 cm ) was
CH O), 274 (24), 144 (20), 138 (71) and 137 (29 ): and the
added, and the mixture filtered to give colourless needles of 4,6-
dichlorobenzene-1,3-dicarboxylic acid (24 g, 38%); mp 276–
2
hexacycle 27 as a red solid (220 mg, 44%); mp 280–285 ЊC
+
18
3
decomp. (Found: M , 304.0931. C H O requires 304.0888);
278 ЊC (from ethanol, lit., 280 ЊC); λmax(EtOH)/nm 221 (ε/dm
Ϫ1 Ϫ1 Ϫ1
2
3
12
Ϫ1
νmax/cm
(CHCl ) 1630 (C᎐O), 1600 and 1570 (C᎐C);
mol cm 39 400) and 244 (18 600); νmax/cm (Nujol) 2400–
3200 (OH), 1700 (C᎐O) and 1590 (C᎐C); δ [(CD ) SO] 7.6 (1 H,
3
δ (CDCl ) 7.31 (1 H, s), 7.45 (1 H, t, J 8), 7.48 (1 H, t, J 8), 7.67
H
3
᎐
᎐
H
3 2
(1 H, t, J 8), 7.73 (1 H, d, J 8), 7.81 (2 H, d, J 8), 7.98 (1 H, dd, J
s) and 8.4 (1 H, s); δ [(CD ) SO] 129.0, 132.2, 134.5, 136.1 and
C 3 2
1
54
J. Chem. Soc., Perkin Trans. 2, 1997