Bender et al.
43
(4) value 102 to 103o C for non-deuterated 2) after recry-
stallization from 95% ethanol. 1H NMR: 7.22–7.31 (m,
2.67H, 2 aromatics + residual CHCl3), 6.95–7.06 (m, 2.00H,
2 aromatics), 6.75 and 6.73 (d and d, 2.04H, H-5 and H-10,
J5,6 = J9,10 = 11.5), 6.66 (d, 0.07H, residual H-8, J8,9 = 4.5),
6.07 (d, 0.98H, H-9, J9,10 = 11.5), and 5.95 (d, 0.99H, H-6,
3.38 (q, 0.09H, residual H-1, J1,2 = J1,5 = J1,8 = 6.5), 3.19 (d,
1.03H, H-2, J2,8 = 6.5), and 2.94 (d, 1.01H, H-8, J2,8 = 6.5).
The last band gave ca. 1 mg (2%) of tetracycle 4a. 1H NMR:
7.16–7.28 (m, 4.38H, 4 aromatics and residual CHCl3),
4.32–4.36 (m, 2.00H, H-1 and H-6), 3.28 (q, 1.01H, H-5,
J5,1 = J5,2 = J5,6 = 4.5), and 2.91–2.98 (m, 1.00H, H-2 and
residual H-3).
1
J6,5 = 11.5). Also note H NMR data given in entry number
1 in Table 1.
The second band containing the triene starting material
and COT product was rechromatographed on a Silica Gel
60/AgNO3 column (0.9 cm × 11 cm; 0.25% ethyl acetate –
hexane), monitored by UV spectroscopy at λ = 300 nm. The
first band gave 29.0 mg (69%) of recovered triene starting
Direct irradiation of 8-deuterio-COT (2a)
A solution containing 366.5 mg (2.04 mmol) of 2a in
200 mL of cyclohexane was irradiated directly in Cell B
(Pb(NO3)2 filter) for 96 h. The photolysate was concentrated
to 8 mL and chromatographed (in four 2 mL aliquots) on a
Lobar column with 1% ethyl acetate – hexane solvent; the
eluant was monitored by UV spectroscopy at λ = 300 nm.
The last band from the column contained 116.6 mg (32%) of
1
material 1a. H NMR: 7.16–7.22 (m, 1.99H, 2 aromatics),
7.06–7.13 (m, 2.03H, 2 aromatics), 6.71 (d, 1.00H, H-8, J8,1 =
1), 6.42 (d, 1.00H, H-4, J4,5 = 10), 5.93 (d, 0.97H, H-5, J5,4 =
10), 4.22 (br s, 0.99H, H-1), and 4.00 (t, 0.07H, residual H-
6, J6,1 = J6,5 = 4.5). The second band gave 7.0 mg (17%) of
COT product 2b. 1H NMR: 7.22–7.31 (m, 2.07H, 2
aromatics + residual CHCl3), 6.95–7.06 (m, 2.00H, 2
aromatics), 6.75 and 6.73 (d and br s, 1.98H, H-5 and H-10,
J5,6 = 11.5), 6.66 (br s, 0.98H, H-8), 6.07 (dd, 0.10H, resid-
ual H-9, J9,8 = 4.5, J9,10 = 11.5), and 5.95 (d, 1.02H, H-6,
labelled
6-cyano-2,3-benzobicyclo[4.2.0]octa-2,4,7-triene
(5a). 1 H NMR: 7.10–7.30 (m, 4.28H, 4 aromatics + residual
CHCl3), 6.46 (d, 1.00H, H-4, J4,5 = 10), 6.19 (dd, 0.06H, re-
sidual H-7, J7,8 = 2.8, J7,1 = 1), 6.07 (d, 0.95H, H-8, J8,1 =
1), 5.85 (d, 0.98H, H-5, J5,4 = 10), and 4.46 (br s, 0.97H, H-
1). The first band from the column contained COT 2a and
triene 1a, and was rechromatographed in three equal aliquots
on a Silica Gel 60/AgNO3 column (0.9 cm × 11 cm; 0.5%
ethyl acetate – hexane). The first band gave 93.8 mg (26%)
1
J6,5 = 11.5); also note the H NMR data given in entry num-
ber 3, Table 1.
Thermolysis of triene 5a
1
of triene 1a. H NMR: 7.16–7.22 (m, 2.05H, 2 aromatics),
A solution of 8.5 mg (0.047 mmol) of 5a in 5 mL of n-
nonane was refluxed (ca. 150°C) under a nitrogen atmo-
sphere for 5.2 h. The thermolysis product was chromato-
graphed on Silica Gel 60 (0.9 cm × 10 cm) with 3% ethyl
acetate – hexane to give 6.0 mg (71%) of 8-deuterio-COT
7.06–7.13 (m, 2.07H, 2 aromatics), 6.71 (d, 1.00H, H-8, J8,1 =
1), 6.42 (d, 1.00H, H-4, J4,5 = 10), 5.93 (d, 0.98H, H-5, J5,4 =
10), 4.22 (br s, 1.01H, H-1), and 4.00 (t, 0.07H, residual H-
6, J6,1 = J6,5 = 4.5). The second band gave 133.8 mg (37%)
1
of recovered COT starting material (2a). H NMR: 7.22–
1
(2a); for H NMR details note entry 7, Table 1.
7.31 (m, 2.08H, 2 aromatics + residual CHCl3), 6.95–7.06
(m, 2.00H, 2 aromatics), 6.75 and 6.73 (d and d, 1.95H, H-5
and H-10, J5,6 = J9,10 = 11.5), 6.66 (d, 0.08H, residual H-8,
J8,9 = 4.5), 6.07 (d, 0.94H, H-9, J9,10 = 11.5), and 5.95 (d,
0.96H, H-6, J6,5 = 11.5).
Direct irradiation of 7-deuterio-6-cyano-triene (i.e., triene
5a)
A solution containing 20.2 mg (0.09 mmol) of 5a in
40 mL of cyclohexane was irradiated directly in Cell C (Py-
rex filter) for 1.5 h. The photolysate was worked up as in the
case of the direct irradiation of unlabelled triene 5 (2) to
give ca. 1 mg (5%) of 2-cyanonaphthalene and ca. 1 mg
Thermolysis of triene 1a
A solution of 8.0 mg (0.044 mmol) of 1a in 4 mL of n-
nonane was refluxed (ca. 150°C) under a nitrogen atmo-
sphere for 8 h. The thermolysis product was chromatogra-
phed on Silica Gel 60 (0.9 cm × 10 cm) with 3% ethyl
acetate – hexane to give 7.1 mg (89%) of 8-deuterio-COT
1
(5%) of 8-deuterio-COT (2a); for the H NMR details note
entry number 8, Table 1; 8.5 mg (42%) of recovered triene
5a (1H NMR: 7.10–7.30 (m, 4.50H, 4 aromatics + residual
CHCl3), 6.46 (d, 1.00H, H-4, J4,5 = 10), 6.19 (dd, 0.06H, re-
sidual H-7, J7,8 = 2.8, J7,1 = 1), 6.07 (d, 0.98H, H-8, J8,1 =
1), 5.85 (d, 1.00H, H-5, J5,4 = 10), and 4.46 (br s, 1.00H, H-
1)); and 7.5 mg (37%) of semibullvalene 6a (1H NMR:
7.32–7.40 (m, 1.00H, 1 aromatic), 7.06–7.25 (m, 3.10H, 3
1
(2a) (the H NMR data are given in entry 2, Table 1).
Direct irradiation of triene 1a
A solution containing 42.3 mg (0.24 mmol) of 1a in
40 mL of cyclohexane was irradiated directly in Cell C (Py-
rex filter) for 3.2 h. The photolysate was concentrated and
chromatographed on Silica Gel 60 (0.9 cm × 7 cm) with 4%
ethyl acetate – hexane to remove polymeric materials, and
then rechromatographed on a Lobar column with 2% ethyl
acetate – hexane solvent; the eluant was monitored by UV
spectroscopy at λ = 265 nm. The first band off the column
gave 3.3 mg (11%) of naphthalene-d1. The second band con-
tained a mixture of the triene starting material and COT
product. The third band contained ca. 1 mg (2%) of semi-
aromatics + residual CHCl3), 5.70 (d, 0.95H, H-6, J6,5
=
2.5), 5.20 (dd, 0.06H, residual H-7, J7,6 = 5.0, J7,8 = 2.5),
4.22 (d, 1.01H, H-5, J5,6 = 2.5), 3.68 (d, 1.01H, H-2, J2,8
7.0), and 3.35 (d, 1.02H, H-8, J8,2 = 7)).
=
Acknowledgements
The authors thank Paul Bradley England for technical as-
sistance and gratefully acknowledge financial support from
the Natural Sciences and Engineering Research Council of
Canada (NSERC).
1
bullvalene 3a. H NMR: 7.22–7.31 (m, 1.00H, 1 aromatic),
7.03–7.26 (m, 5.14H, 3 aromatics + residual CHCl3), 6.30
(d, 1.03H, H-6, J6,5 = 2.5), 4.04 (d, 1.02H, H-5, J5,6 = 2.5),
© 2003 NRC Canada