Apparatus for photolysis
J = 8.1 Hz), 7.65–7.70 (m, 2H), 7.58 (dd, 2H, J = 8.1, 7.0 Hz),
7.49–7.54 (m, 2H), 6.98 (dd, 1H, J = 2.8, 1.0 Hz), 6.62 (d, 1H,
J = 8.8 Hz), 6.61 (d, 1H, J = 8.0 Hz), 6.55 (dd, 1H, J = 8.8,
2.8 Hz), 5.35 (dd, 1H, J = 8.0, 1.0 Hz), 4.35 (br s, 1H).
13C-NMR (100 MHz, CDCl3): δ 153.7, 149.8, 144.1, 141.9,
137.3, 131.6, 129.1, 128.4, 128.3, 125.6, 123.7, 121.9, 119.0,
115.3, 111.8, 110.3, 88.8, 52.4.
As the light source, a high-pressure mercury lamp was
employed with colored-glass filters. The merry-go-round
apparatus for irradiation is described elsewhere.39 Filtering of
> 420 nm and > 500 nm light was according to the previous
method.40
CT absorption spectra of ACN with BQs and measurement of Keq
6b,10b-Dihydrobenzo[3,4]cyclobuta[1,2-a]acenaphthylene-
7,10-dione (5a). Dark red prisms, mp > 300 ЊC. EI-MS: m/z 258.
1H-NMR (400 MHz, CDCl3): δ 7.71 (d, 2H, J = 8.3 Hz), 7.56 (d,
2H, J = 7.5 Hz), 7.50 (dd, 2H, J = 8.3, 7.5 Hz), 6.48 (s, 2H), 5.24
(s, 2H). 13C-NMR (100 MHz, CDCl3): δ 182.1, 152.3, 138.9,
137.6, 136.4, 132.4, 127.9, 124.6, 121.8, 52.9.
A solution of 2.0 × 10Ϫ1 M of ACN in DCE was prepared in a
quartz cuvette and the UV-Vis absorption spectrum was
recorded. Then a stock solution (0.10 M) of BQs in DCE was
added with a microsyringe and the absorption spectrum of the
resultant solution was recorded. To determine the equilibrium
constant of CT complexes, BQs were incrementally added so
that the concentration of BQs typically ranged from 2.0 × 10Ϫ3
to 1.0 × 10Ϫ2 M, and the absorption change at an appro-
priate wavelength which does not overlap with that of ACN
and BQs was chosen to apply to the procedure of Benesi and
Hildebrand.10 Except for the case of DDQ, the λmax of the CT
complex is concealed among the intensive absorption of ACN
and BQs in the region of 400–500 nm, so a wavelength with a
large absorption gap in the presence and in the absence of BQs
was chosen to determine Keq as shown in Table 1.
2’-Chloro-6b,8a-dihydrospiro[acenaphtho[1,2-b]oxete-8,1’-
cyclohexa[2’,5’]dien]-4’-one (3d). Colorless solid. EI-MS: m/z
1
294 (Mϩ), 296 (Mϩ ϩ 2). H-NMR (400 MHz, CDCl3): δ 7.88
(m, 1H), 7.82 (d, 1H, J = 8.3 Hz), 7.63 (m, 2H), 7.57
(dd, 1H, J = 7.0, 8.0 Hz), 7.26 (d, 1H, J = 7.0 Hz), 6.55 (d, 1H,
J = 5.6 Hz), 6.50 (d, 1H, J = 2.0 Hz), 6.12 (d, J = 10.0 Hz), 5.70
(dd, 1H, J = 10.0, 2.0 Hz), 4.88 (d, 1H, J = 5.6 Hz).
9-Chloro-6b,11b-dihydroacenaphtho[1,2-b][1]benzofuran-10-
ol (4d). Colorless powder, mp 182.0–183.0 ЊC (dec.). Anal.
Calcd for C18H11ClO2: C, 73.35; H, 3.76; Cl, 12.03; O, 10.86.
Found: C, 73.22; H, 3.99; Cl, 11.89. EI-MS: m/z 294 (Mϩ),
Photochemical reaction of ACN in the presence of BQs
1
296 (Mϩ ϩ 2). H-NMR (400 MHz, CDCl3): δ 7.79 (d, 1H,
As a typical run, irradiation of ACN in the presence of TMBQ
in DCE will be described. A solution of 304.0 mg (2.0 mmol) of
ACN and 328.0 mg (2.0 mmol) of TMBQ in 100 ml of DCE
was prepared in two Pyrex test tubes and purged with argon
gas for 30 min and sealed. This solution was then irradi-
ated with > 420 nm light in a merry-go round apparatus for
24 hours. After evaporation of the solvent under reduced pres-
sure, the residual solid (642 mg) was flash-chromatographed
(silica gel, eluent: hexane), which gave 18.3 mg (6.0%) of ACN,
25.2 mg (8.3%) of cisoid-1, and 36.2 mg (11.9%) of transoid-1.
Gradient elution (hexane–ethyl acetate 20 : 1 then 8 : 1) gave
61.8 mg (18.8%) of TMBQ and 488.5 mg (77.3%) of cisoid-2a
in this order. Irradiation in AN gave a similar result.
J = 8.0 Hz), 7.69 (t, 1H, J = 6.0 Hz), 7.68 (d, 1H, J = 7.8 Hz),
7.59 (dd, 1H, J = 8.0, 7.8 Hz), 7.52 (d, 2H, J = 6.0 Hz), 7.14
(s, 1H), 6.73 (s, 1H), 6.62 (d, 1H, J = 8.0 Hz), 5.33 (d, 1H,
J = 8.0 Hz), 5.05–5.18 (br s, 1H). 13C-NMR (100 MHz, CDCl3):
δ 153.4, 145.6, 143.5, 141.3, 137.2, 131.5, 128.5, 128.4, 128.3,
125.7, 123.8, 122.0, 119.0, 112.5, 110.1, 110.0, 89.3, 52.2.
cis-cisoid-cis-6c-Bromo-6b,6c,10a,10b-tetrahydrobenzo[3,4]-
cyclobuta[1,2-a]acenaphthylene-7,10-dione (cisoid-2e). This
compound was obtained as
a dark brown solid being
contaminated by cyclobutene 5a. EI-MS: m/z 338 (Mϩ), 340
(Mϩ ϩ 2). 1H-NMR (400 MHz, CDCl3): δ 7.88 (d, 1H,
J = 8.4 Hz), 7.82 (d, 1H, J = 8.4 Hz), 7.72 (t, 1H, J = 8.4 Hz),
7.64 (d, 1H, J = 8.4 Hz), 7.59 (dd, 1H, J = 8.4, 7.3 Hz), 7.46
(d, 1H, J = 7.3 Hz), 7.17 (d, 1H, J = 10.5 Hz), 7.00 (dd, 1H,
J = 10.5, 1.2 Hz), 4.75 (dd, 1H, J = 7.0, 1.0 Hz), 4.32 (t, 1H,
J = 7.0 Hz), 3.62 (dt, 1H, J = 7.0, 1.0 Hz).
cis-cisoid-cis-6c,8,9,10a-Tetramethyl-6b,6c,10a,10b-tetra-
hydrobenzo[3,4]cyclobuta[1,2-a]acenaphthylene-7,10-dione
(cisoid-2a). Yellow prisms, mp 201.0–202.0 ЊC. Anal. Calcd for
C22H20O2: C, 83.52; H, 6.37; O, 10.11. Found: C, 83.44; H,
1
6.51%. EI-MS: m/z 316 (Mϩ). H-NMR (400 MHz, CDCl3):
δ 7.58 (d, 2H, J = 8.1 Hz), 7.40 (dd, 2H, J = 8.1, 7.2 Hz),
7.09 (d, 2H, J = 7.2 Hz), 4.13 (s, 2H), 1.70 (s, 6H), 1.01 (s, 6H).
13C-NMR (100 MHz, CDCl3): δ 199.3, 145.0, 143.2, 141.7,
131.0, 128.0, 123.3, 121.7, 53.2, 52.9, 19.9, 12.4.
9-Bromo-6b,11b-dihydroacenaphtho[1,2-b][1]benzofuran-10-
ol (4e). Pale brown powder. EI-MS: m/z 338 (Mϩ), 340
(Mϩ ϩ 2). 1H-NMR (400 MHz, CDCl3): δ 7.72 (d, 1H, J = 7.8
Hz), 7.67 (t, 1H, J = 6.3 Hz), 7.64 (d, 1H, J = 7.7 Hz), 7.57
(dd, 1H, J = 7.8, 7.7 Hz), 7.52 (d, 2H, J = 6.3 Hz), 7.14 (d, 1H,
J = 0.6 Hz), 6.86 (d, 1H, J = 0.6 Hz), 6.62 (d, 1H, J = 7.9 Hz),
5.30 (d, 1H, J = 7.9 Hz), 5.02–5.18 (br s, 1H). 13C-NMR (100
MHz, CDCl3): δ 153.8, 146.6, 143.5, 141.4, 137.3, 131.7, 129.6,
128.36, 128.33, 125.7, 123.8, 122.0, 119.1, 112.8, 111.8, 109.1,
89.4, 52.2.
2’,5’-Dimethyl-6b,8a-dihydrospiro[acenaphtho[1,2-b]oxete-
8,1’-cyclohexa[2’,5’]dien]-4’-one (3b). Recrystallized from
dichloromethane–hexane, pale yellow prisms which were
significantly sensitive to white light, mp 104.5–108.5 (dec.) ЊC.
Anal. Calcd for C20H16O2: C, 83.31; H, 5.59; O, 11.10. Found:
C, 83.20, H, 5.72%. EI-MS: m/z 288 (Mϩ). 1H NMR (400 MHz,
CDCl3): δ 7.82 (dd, 1H, J = 7.2, 2.2 Hz), 7.80 (d, 1H, J =
8.3 Hz), 7.52–7.64 (m, 3H), 7.33 (dd, 1H, J = 3.2, 1.2 Hz),
7.23 (d, 1H, J = 7.2 Hz), 6.35 (d, 1H, J = 5.2 Hz), 5.86 (dd, 1H,
J = 3.2, 1.2 Hz), 4.59 (d, 1H, J = 5.2 Hz), 2.00 (d, 3H, J =
1.2 Hz), 1.65 (d, 3H, J = 1.2 Hz). 13C-NMR (100 MHz, CDCl3):
δ 186.4, 143.8, 143.1, 141.5, 141.0, 139.9, 135.5, 134.2, 131.8,
128.20, 128.17, 125.7, 124.3, 121.4, 121.3, 81.7, 80.9, 52.9, 16.0,
15.9.
8-Chloro-6b,10b-dihydrobenzo[3,4]cyclobuta[1,2-a]ace-
naphthylene-7,10-dione (5b). Dark red powder, mp 191.0–
193.5 ЊC (dec.). EI-MS: m/z 292 (Mϩ), 294 (Mϩ ϩ 2). 1H-NMR
(400 MHz, CDCl3): δ 7.72 (d, 2H, J = 7.8 Hz), 7.58 (d, 1H,
J = 7.0 Hz), 7.56 (d, 1H, J = 7.0 Hz), 7.51 (dd, 1H, J = 8.0,
7.0 Hz), 7.50 (dd, 1H, J = 8.0, 7.0 Hz), 6.73 (s, 1H), 5.21–5.27
(m, 2H). 13C-NMR (100 MHz, CDCl3): δ 179.4, 173.4, 152.3,
150.8, 143.4, 136.94, 136.88, 133.3, 133.2, 132.2, 127.81, 127.85,
124.63, 124.67, 121.77, 121.81, 52.5, 52.2.
6b,11b-Dihydroacenaphtho[1,2-b][1]benzofuran-10-ol
(4c).
Recrystallized from dichloromethane–hexane, dark brown
cubes, mp 212.0–213.5 ЊC (dec.). Anal. Calcd for C18H12O2:
C, 83.06; H, 4.65; O, 12.29. Found: C, 82.92, H, 4.85%.
cis-cisoid-cis-6c,8-Dichloro-6b,6c,10a,10b-tetrahydrobenzo-
[3,4]cyclobuta[1,2-a]acenaphthylene-7,10-dione (cisoid-2g). This
compound was obtained as a dark red powder being contamin-
ated by cyclobutene 5b. EI-MS: m/z 328 (Mϩ), 330 (Mϩ ϩ 2),
1
EI-MS: m/z 260. H-NMR (400 MHz, CDCl3): δ 7.78 (d, 1H,
J. Chem. Soc., Perkin Trans. 2, 2002, 734–745
743