9.10 (2 H, m), 8.36 (1 H, m), 8.03 (1 H, dd, J 7.8 and 1.7), 7.92
(1 H, AB system, J 8.5), 7.89 (1 H, s), 7.82 (1 H, AB system,
J 8.5), 7.67 (4 H, m), 5.92 (1 H, d, J 1.1) and 5.73 (1 H, d, J 1.1);
δC(75.47 MHz, CDCl3) 138.6, 135.5, 133.9, 130.6, 130.4, 129.9,
129.8, 128.6, 128.4, 128.2, 128.1, 127.9, 127.5, 126.6, 126.4 (two
isochronous carbon atoms), 126.3 (two isochronous carbon
chloride (0.14 g, 0.2 mmol) and copper() iodide (0.01 g, 0.05
mmol) was added to a deaerated solution of 6-bromochrysene
(16, 0.4 g, 1.3 mmol)22 and ethynyltrimethylsilane (0.19 g, 1.9
mmol) in triethylamine (40 ml) and the reaction mixture was
heated at reflux for 48 h.21 After cooling to room temperature
the reaction mixture was filtered and the filtrate was concen-
trated in vacuo. Crude 6-(trimethylsilylethynyl)chrysene (17)
was purified by column chromatography [silica, eluent light
petroleum (40–60)–ethyl acetate 15:1 v/v]. Yield 17 (0.28 g, 0.9
mmol, 69%, brownish waxy solid). δH (300.13 MHz, CDCl3)
9.00 (1 H, s), 8.77 (2 H, m), 8.68 (1 H, d, J 9.1), 8.53 (1 H, m),
8.02 (1 H, d, J 9.1), 7.98 (1 H, dd, J 8.0 and 1.3), 7.70 (4 H, m)
and 0.40 (9 H, s). Compound 17 (0.28 g, 0.9 mmol) was con-
verted into 5 by treatment with anhydrous potassium carbonate
(0.03 g) in methanol (30 ml) at room temperature for 5 h. After
removal of the solvent under reduced pressure dichloro-
methane (60 ml) was added, the organic layer was dried over
magnesium sulfate, filtered and concentrated under reduced
pressure. Pure 5 was obtained as a brownish solid (yield 0.14 g,
0.56 mmol, 65%). Mp 146 ЊC (decomp.); δH (300.13 MHz,
CDCl3) 9.05 (1 H, s), 8.77 (3 H, m), 8.57 (1 H, dd, J 6.5 and 2.4),
8.03 (2 H, m), 7.72 (4 H, m) and 3.58 (1 H, s); δC(75.47 MHz,
CDCl3) 132.2, 131.5, 130.3, 128.8, 128.6 (two isochronous car-
bon atoms), 127.3, 127.2 (two isochronous carbon atoms),
127.1, 127.0, 126.8, 126.7, 126.4, 123.3, 123.0, 121.2, 120.9,
atoms), 126.0 and 117.9; m/z (MS) 290 and 288 (M ϩ with iso-
tope pattern).
6-(1-Chloroethenyl)chrysene (7). A mixture of 9 (1.50 g, 5.6
mmol) in CH2Cl2 and PCl5 (1.50 g, 7.2 mmol) in CH2Cl2 (50 ml)
was heated at reflux for 48 h. After cooling to room tem-
perature, water (50 ml) was added. The organic layer was separ-
ated, washed with a saturated sodium bicarbonate solution (50
ml) and water (50 ml), dried over magnesium sulfate, filtered
and concentrated under reduced pressure. Crude 6-(1-chloro-
ethenyl)chrysene (7) was purified by column chromatography
(silica, eluent diethyl ether–hexane 2:1 v/v). Yield 7, 0.77 g (2.7
mmol, 48%, brownish solid). Mp 151–154 ЊC; δH (300.13
MHz, CDCl3) 8.80 (2 H, m), 8.76 (1 H, s), 8.70 (1 H, d, J 9.1),
8.34 (1 H, m), 8.04 (1 H, d, J 9.1), 8.00 (1 H, dd, J 7.9 and 1.4),
7.70 (4 H, m), 5.96 (1 H, d, J 1.1) and 5.74 (1 H, d, J 1.1);
δC(75.47 MHz, CDCl3) 139.8, 135.7, 132.2, 130.8, 130.5, 129.2,
128.9, 128.6, 128.3, 127.2 (two isochronous carbon atoms),
127.0, 126.7, 126.3, 126.2, 123.5, 123.0, 122.3, 120.9 and 118.0;
m/z (MS) 290 and 288 (M ϩ with isotope pattern).
118.9 and 81.9; ν/cmϪ1 3277 (᎐C–H stretch), 2100 (C᎐C–H
᎐
᎐
᎐
2-Bromobenzo[c]phenanthrene (14). 70.0 mg (0.31 mmol) of
benzo[c]phenanthrene (10) was treated with 0.62 g (0.91 mmol)
of alumina supported copper() bromide in carbon tetra-
chloride (25 ml)20 at 35 ЊC for 2 days. After filtration the residue
was washed with 20 ml of carbon tetrachloride. The combined
filtrate was concentrated under reduced pressure and the resi-
due purified by column chromatography (silica, eluent hexane)
giving 70.0 mg (0.23 mmol, 74%) of pure 14 as pale yellow oil.
δH (300.13 MHz, CDCl3) 9.11 (1 H, m), 9.04 (1 H, d, J 8.6), 8.50
(1 H, m), 8.18 (1 H, s), 8.02 (1 H, dd, J 7.5 and 1.8), 7.91 (1 H, d,
J 8.5) and 7.70 (5 H, m); δC(75.47 MHz, CDCl3) 133.6, 131.5,
131.4, 131.1, 130.7, 130.4, 130.0, 128.7, 128.3, 128.2, 128.0,
127.7, 126.9, 126.8, 126.5, 126.2, 125.7 and 121.8; m/z (MS) 306
᎐
stretch); m/z (MS) 252 (M ϩ) (Found: C, 95.05; H, 4.76. Calc.
for C20H12: C, 95.21; H, 4.79).
Benz[l]acephenanthrylene (2). Compound 2 was initially
purified from the 900 ЊC pyrolysate by column chromatography
(silica, eluent hexane–benzene 7:3 v/v) followed by recrystal-
lization from ethanol. Analytically pure 2 was obtained using
preparative HPLC. Mp 175–177 ЊC; δH (300.13 MHz, CDCl3)
9.21 (1 H, d, J 8.4), 8.95 (1 H, m), 8.09 (1 H, s), 8.02 (1 H, dd, J
7.9 and 1.2), 7.95 (1 H, AB system, J 8.7), 7.92 (1 H, AB
system, J 8.7), 7.74 (3 H, m), 7.64 (1 H, m), 7.23 (1 H, AB
system, J 5.3) and 7.14 (1 H, AB system, J 5.3); δC(75.47 MHz,
CDCl3) 140.0, 139.0, 134.0, 133.3, 131.9, 131.3, 129.0, 128.7,
128.4, 128.0, 127.9, 127.3, 126.9, 126.6, 126.5, 126.4, 126.0 and
122.6 (two 13C resonances are not resolved); m/z (MS) 252
(M ϩ with isotope pattern).
2-Ethynylbenzo[c]phenanthrene (4). Bis(triphenylphosphine)-
palladium dichloride (8.0 mg, 0.01 mmol) and copper() iodide
(4 mg, 0.03 mmol) was added to a deaerated solution of 60.0
mg (0.20 mmol) of 14 and 40.0 mg (0.40 mmol) of ethynyltri-
methylsilane in anhydrous triethylamine (20 ml) and the reac-
tion mixture was stirred for two days.21 After filtration the resi-
due was washed with triethylamine (10 ml) and the combined
filtrate was concentrated under reduced pressure. The residue
was purified by column chromatography (silica, eluent hexane)
giving 25.9 mg (0.08 mmol, 40%) of pure 2-(trimethylsilyl-
ethynyl)benzo[c]phenanthrene (15) as yellow oil. δH (300.13
MHz, CDCl3) 9.09 (2 H, m), 8.58 (1 H, m), 8.10 (1 H, s), 8.01 (1
H, dd, J 7.6 and 1.7), 7.89 (1 H, AB system, J 8.5), 7.77 (1 H,
AB system, J 8.5), 7.70 (4 H, m) and 0.38 (9 H, s). Compound
15 (20.0 mg, 0.06 mmol) was converted into 4 by treatment with
anhydrous potassium carbonate (5 mg) in methanol (5 ml) at
room temperature for 4 h. After removal of the solvent under
reduced pressure chloroform (10 ml) was added and the result-
ing solution washed with water (2 × 10 ml). The organic layer
was dried over magnesium sulfate and concentrated under
reduced pressure. Pure 4 was obtained as a brown oil (14 mg,
0.05 mmol, 95%). δH (300.13 MHz, CDCl3) 9.10 (2 H, m), 8.60
(1 H, m), 8.14 (1 H, s), 8.02 (1 H, dd, J 7.5 and 1.8), 7.91 (1 H,
AB system, J 8.5), 7.78 (1 H, AB system, J 8.5), 7.70 (4 H, m)
and 3.54 (1 H, s); δC(75.47 MHz, CDCl3) 134.0, 132.7, 132.5,
130.1, 129.9, 128.6, 128.5, 128.2, 128.1, 128.0, 127.9, 126.6,
126.6, 126.5, 126.4, 126.4, 126.3, 118.8, 82.2 and 81.8; ν/cmϪ1
(M ϩ) (Found: C, 94.89; H, 4.77. Calc. for C20H12: C, 95.21; H,
4.79).
Benz[j]acephenanthrylene (3). Compound 3 was isolated from
the 1000 ЊC pyrolysate by column chromatography (silica,
eluent hexane–benzene 9:1 v/v) followed by recrystallization
from ethanol. Mp 172–173 ЊC (mp 170–171 ЊC);9 all analytical
data were in agreement with those previously reported.9
Benzo[j]fluoranthene (1). All analytical data were in agree-
ment with those previously reported.10
General flash vacuum thermolysis procedure
A commercial Thermolyne 21100 tube furnace containing an
unpacked quartz tube (length 40 cm and diameter 2.5 cm) was
used for all FVT experiments. Temperature–conversion curves
were determined by evaporating 50 mg aliquots of either 6 or 7
(sublimation temperature 140 ЊC and sublimation rate 50 mg
h
Ϫ1) into the quartz tube at a pressure of 10Ϫ2 Torr and the
temperatures are shown in Table 1. In the case of FVT of 5 and
19 50 mg aliquots were used (5; sublimation temperature 140 ЊC
and 19; sublimation temperature 90 ЊC and sublimation rate 60
mg hϪ1). The pyrolysate product composition was determined
1
with H, 13C NMR spectroscopy, capillary GC, capillary GC–
MS and HPLC.
Semi-empirical AM1 calculations
Calculations were performed with AM1 as implemented in
MOPAC 6.0.19 Geometry optimization was performed without
symmetry constraints (keyword PRECISE). Transition states
(TS)§ were located using a reaction coordinate and, sub-
sequently, refined using the Eigenvector Following routine
᎐
᎐
3300 (᎐C–H stretch), 2100 (C᎐C–H stretch); m/z (MS) 252
᎐
᎐
(M ϩ) (Found: C, 95.16; H, 4.75. Calc. for C20H12: C, 95.21; H,
4.79).
6-Ethynylchrysene (5). Bis(triphenylphosphine)palladium
J. Chem. Soc., Perkin Trans. 2, 1997
707