W. Wang et al. / Tetrahedron 63 (2007) 12367–12372
12371
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s, ]CH), 5.81 (2H, s, ]CH), 7.44 (4H, s, ArH). IR (KBr)
1742 cmꢁ1. LRMS m/z 355 (MH+). HRMS (MH+) calcd
for C20H19O6 355.1182, found: 355.1182. Anal. Calcd for
C20H18O6: C, 67.79; H, 5.12. Found: C, 67.59; H, 5.10.
5a and 5a0 in 88% yield (conversion was 4%) from the H
NMR spectral analysis using pyrazine. Compound 5a: mp
1
249–252 ꢂC. H NMR (CDCl3) d 1.65 (6H, s, Me), 4.11
(each 2H, d, J¼12.0 Hz, OCH2), 4.14 (2H, s, CH), 4.53
(each 2H, d, J¼11.6 Hz, OCH2), 5.14(2H, s, ]CH), 7.16–
7.44 (24H, m ArH). IR (KBr) 1717, 1636 cmꢁ1. LRMS m/z
719 (MH+). HRMS (MH+) calcd for C46H39O8 719.2645,
found: 719.2625. Compound 5a0: mp 238–241 ꢂC. 1H
NMR (CDCl3) d 1.63 (6H, s, Me), 4.11 (2H, s, CH), 4.11
(each 2H, d, J¼11.6 Hz, OCH2), 4.70 (each 2H, d,
J¼11.6 Hz, OCH2), 5.16 (each 2H, s, ]CH), 7.16–7.44
(24H, m ArH). IR (KBr) 1717, 1636 cmꢁ1. LRMS m/z 719
(MH+). HRMS (MH+) calcd for C46H39O8 719.2645, found:
719.2619.
4.3. 6,60-Dimethyl-4,40-[1,3-bis(methylenoxy)-
phenylene]-di-2-pyrone (4b)
Compound 4b (2.34 g, 17%) was prepared by a method sim-
ilar to that of 4a by using 4-hydroxy-6-methyl-2-pyrone
(5.00 g, 39.6 mmol), DBU (6.03 g, 39.6 mmol), and 1,3-
bis(chloromethyl) benzene (3.47 g, 19.8 mmol). Compound
1
4b: mp 191–194 ꢂC. H NMR (CDCl3) d 2.22 (6H, s, Me),
5.03 (4H, s, OCH2), 5.48 (2H, s, ]CH), 5.85 (2H, s,
]CH), 7.37 (2H, d, J¼8.0 Hz, ArH), 7.38 (1H, s, ArH),
7.44 (1H, t, J¼8.0 Hz, ArH). IR (KBr) 1713 cmꢁ1. LRMS
m/z 355 (MH+). HRMS (MH+) calcd for C20H19O6
355.1182, found: 355.1113. Anal. Calcd for C20H18O6: C,
67.79; H, 5.12. Found: C, 67.88; H, 4.99.
4.6. 5,50-[1,3-Bis(methylenoxy)phenylene]bis(1-methyl-
7,7-diphenyl-2,8-dioxabicyclo-[4.2.0]oct-4-en-3-one) (5b)
A 1:2 mixture of 4b(88 mg, 0.25 mmol, mp 191–194 ꢂC) and
2a (91 mg, 0.50 mmol, mp 48–50 ꢂC) was ground for 10 min
to give a solid solution (mp 40–43 ꢂC), which was sand-
wiched between two Pyrex glass plates. The solid solution
was irradiated for 6 h under nitrogen atmosphere at room
temperature. The reaction solid was separated by preparative
TLC using ethyl acetate–hexane (1:1 v/v) as eluent to give 5b
(19 mg, 11% yield). The calculated yields of 5b in the photo-
reactions of the 1:2 mixture of 4b (35 mg, 0.10 mmol) and 2a
(36 mg, 0.20 mmol) for 1.5, 3, 6, 9 h were 89, 95, 51, 47%
(conversions were 9, 20, 45, 53%, respectively) from the
1H NMR spectral analyses using pyrazine (4.0 mg,
0.05 mmol) as internal standard substance. Similar photore-
action to 1:2 mixed crystals (mp 142–146 ꢂC) of 4b (35 mg,
0.10 mmol) and 2a (36 mg, 0.20 mmol) prepared by crystal-
lization from CHCl3 for 3 h gave 5b in 99% yield (conversion
was 28%). Similar photoreaction of the 1:2 mixture of 4b and
2a without crystallization for 3 h in water as the disperse
phase gave 5b in 93% yield (conversion was 7%). Compound
4.4. 6,60-Dimethyl-4,40-[1,4-bis(methylenoxy)-
phenylene]-di-2-pyrone (4c)
Compound 4c (2.52 g, 18%) was prepared by a method sim-
ilar to that of 4a by using 4-hydroxy-6-methyl-2-pyrone
(5.00 g, 39.6 mmol), DBU (6.03 g, 39.6 mmol), and 1,4-
bis(chloromethyl) benzene (3.47 g, 19.8 mmol). Compound
1
4c: mp 210–212 ꢂC. H NMR (CDCl3) d 2.22 (6H, s, Me),
5.03 (4H, s, ]CH2), 5.47 (2H, s, ]CH), 5.84 (2H, s, 5-
H), 7.40 (4H, s, ArH). IR (KBr) 1722 cmꢁ1. LRMS m/z
355 (MH+). Anal. Calcd for C20H18O6: C, 67.79; H, 5.12.
Found: C, 67.66; H, 5.16.
4.5. 5,50-[1,2-Bis(methylenoxy)phenylene]bis(1-methyl-
7,7-diphenyl-2,8-dioxabicyclo-[4.2.0]oct-4-en-3-one)
(5a) and (5a0)
1
A 1:2 mixture of 4a (88 mg, 0.25 mmol, mp 190–193 ꢂC) and
2a (91 mg, 0.50 mmol, mp 48–50 ꢂC) was ground for 10 min
to give a solid solution (mp 41–44 ꢂC), which was sand-
wiched between two Pyrex glass plates. The solid solution
was irradiated for 6 h under nitrogen atmosphere at room
temperature. The reaction solid was separated by preparative
TLC using ethyl acetate–hexane (1:1 v/v) as eluent to give
a mixture of 5a and 5a0 (1:1 mixture) (18 mg, 10% yield),
which were separated by repeated crystallization from di-
ethyl ether. The calculated yields were obtained as follows.
The 1:2 mixture of 4a (35 mg, 0.10 mmol) and 2a (36 mg,
0.20 mmol) was irradiated for 1.5, 3, 6, 9 h under nitrogen at-
mosphere at room temperature, respectively. The photoreac-
tion gave a 1:1 mixture of 5a and 5a0 in 86, 91, 54, 29% yields
(conversions were 4, 11, 22, 47%, respectively) from the 1H
NMR spectral analysis using pyrazine (4.0 mg, 0.05 mmol)
as internal standard substance. The 1:2 mixed crystals (mp
134–138 ꢂC) of 4a (35 mg, 0.10 mmol) and 2a (36 mg,
0.20 mmol) prepared by crystallization from CHCl3 was irra-
diated for 3 h under nitrogen atmosphere at room tempera-
ture. The photoreaction gave a 1:1 mixture of 5a and 5a0 in
94% yield (conversion was 18%) from the 1H NMR spectral
analysis using pyrazine as internal standard substance. The
same amount of 1:2 mixture of 4a and 2a without crystalliza-
tion was irradiated for 3 h in water as the disperse phase at
room temperature. The photoreaction gave a 1:1 mixture of
5b: mp 252–255 ꢂC. H NMR (CDCl3) d 1.63 (6H, s, Me),
4.17 (2H, m, CH2), 4.23 (each 2H, d, J¼11.6 Hz, OCH2),
4.65 (each 2H, d, J¼11.6 Hz, OCH2), 5.14 (2H, s, ]CH),
7.19–7.49 (24H, m, ArH). IR (KBr) 1713, 1638 cmꢁ1
.
LRMS m/z 719 (MH+). HRMS (MH+) calcd for C46H39O8
719.2645, found: 719.2692.
4.7. 5,50-[1,4-Bis(methylenoxy)phenylene]bis(1-methyl-
7,7-diphenyl-2,8-dioxabicyclo-[4.2.0]oct-4-en-3-one) (5c)
A 1:2 mixture of 4c (88 mg, 0.25 mmol, mp 210–212 ꢂC)
and 2a (91 mg, 0.50 mmol, mp 48–50 ꢂC) was ground for
10 min to give a solid solution (mp 39–42 ꢂC), which was
sandwiched between two Pyrex glass plates. The solid solu-
tion was irradiated for 6 h under nitrogen atmosphere at
room temperature. The reaction solid was separated by pre-
parative TLC using ethyl acetate–hexane (1:1 v/v) as eluent
to give 5c (19 mg, 11% yield). The calculated yields of 5c in
the photoreactions of the 1:2 mixture of 4c (35 mg,
0.10 mmol) and 2a (36 mg, 0.20 mmol) for 1.5, 3, 6, 9 h
were 81, 87, 38, 35% (conversions were 10, 18, 50, 63%, re-
1
spectively) from the H NMR spectral analyses using pyr-
azine (4.0 mg, 0.05 mmol) as internal standard substance.
Similar photoreaction to 1:2 mixed crystals (mp 142–
146 ꢂC) of 4c (35 mg, 0.10 mmol) and 2a (36 mg,
0.20 mmol) prepared by crystallization from CHCl3 for 3 h