Photochemical generation of benzene-naphthalene biplanemers

Article abstract of DOI:10.1016/j.tetlet.2005.05.092

A direct biplanemer synthesis could be achieved by a quantitative [4π+4π]photocycloaddition of benzyloxy substituted benzene and naphthalene rings (3d,e ? 4d,e). Since the products do not show a thermal Cope rearrangement-in contrast to the related longicyclic conjugated 9,10-benzotricyclo[4.2.2.2^2,5]dodeca-3,7,9-trienes-but a quantitative reverse reaction, they are interesting systems for an optical switching.

Full text of DOI:10.1016/j.tetlet.2005.05.092

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 4975–4977
Photochemical generation of benzene–naphthalene biplanemers
Derong Caoa,* and Herbert Meierb
aLCLC, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, 510650 Guangzhou, PR China
bInstitut fu¨r Organische Chemie der Johannes Gutenberg-Universita¨t, Duesbergweg 10-14, D-55099 Mainz, Germany
Received 18 March 2005; revised 18 May 2005; accepted 20 May 2005
Available online 9June 2005
Abstract—A direct biplanemer synthesis could be achieved by a quantitative [4p+4p]photocycloaddition of benzyloxy substituted
benzene and naphthalene rings (3d,e ¢ 4d,e). Since the products do not show a thermal Cope rearrangement—in contrast to the
related longicyclic conjugated 9,10-benzotricyclo[4.2.2.22,5]dodeca-3,7,9-trienes—but a quantitative reverse reaction, they are inter-
esting systems for an optical switching.
Ó 2005 Elsevier Ltd. All rights reserved.
Biplanemers of aromatic hydrocarbons like the title
compounds represent p systems with an interesting
topology. The spatial and the through-bond interaction
of the p centers conveys these compounds special phys-
ical and chemical properties.1–9 According to the Gold-
stein–Hoffmann classification,10 benzene–naphthalene
biplanemers are longicyclic conjugated systems consist-
ing of three olefinic double bonds and a benzene ring.
The crucial reaction step for the preparation of these
compounds is the [4p+4p]photocycloaddition of naph-
thalene and 1,3-cyclohexadienes.1–9 The then still lack-
ing p bond has to be introduced by a subsequent
reaction step. A further disadvantage of this strategy is
due to the fact that different orientations of the two 4p
components can lead to stereoisomers.9
for 3d and 3e to yield the biplanemers 4d13 and 4e
(Scheme 1).14
The UV spectra of 4d revealed the disappearance of the
naphthalene absorption. As a result of the loss of aro-
maticity in the naphthalene and the benzene ring, which
1
were involved in the photocycloaddition, the H NMR
spectrum of 4d showed a typical change relative to that
of the starting compound 3d. The methylene groups in
the five-membered ring gave AB spin patterns at
d = 3.71/3.97 (2J = À8.8 Hz, 4-H) and 4.60/4.66
(2J = À10.3 Hz, 2-H). The methine proton 9-H gave a
dd signal at d = 3.46 because of its coupling with 8-H
(3J = 10.3 Hz) and 17-H (3J = 7.7 Hz). The other
methine group (8-H) gave a ddd signal at d = 3.20
because it coupled with 9-H (3J = 10.3 Hz), 6-H
(4J = 1.8 Hz), and 18-H (4J = 2.2 Hz). The olefinic pro-
tons on the cyclohexadiene ring resonated at relatively
We found now the first direct [4p+4p]photocycloaddi-
tion of benzene and naphthalene rings. Stimulated by
the addition of electron-rich benzene rings and anthra-
cene,11 we prepared compounds 3a–e12 by phase transfer
mediated Williamson syntheses of 1 and 2 and irradiated
3a–e in benzene with a mercury middle pressure lamp
equipped with a Duran glass filter. A slow stream of
Ar purged through the diluted (ca. 10À3 M) solution,
which were kept at 10 5 °C. Whereas 3b and 3c proved
to be photostable under these conditions, 3a showed a
slow but not really productive photoreaction; however,
a quantitative [4p+4p]photocycloaddition was observed
4
high field, namely at d = 4.31 (d, J = 1.8 Hz, 6-H) and
4
d = 4.95 (d, J = 2.2 Hz, 18-H). Analogous results were
obtained for 4e.
In the reverse process, the products 4d and 4e could be
quantitatively cleaved to 3d and 3e, respectively, by
heating to 90–100 °C. The Cope rearrangement, often
observed for such biplanemers,2,4,6,7 could not be found
under the conditions used here; there were no hints for
one of the two possible [3,3]shift which should lead to
5d,e or 6d,e. Presumably the sterically demanding
CH2–O–CH2 clamp in 4d,e is the reason for the absence
of this rearrangement. On the other hand, the CH2–O–
CH2 linker is a precondition, that the [4p+4p]photo-
cycloaddition, which is well-known for anthracenes14
Keywords: Cycloaddition; Cycloreversion; Photoreaction.
*
Corresponding author. Tel.: +86 2085231666; fax: +86
2085232903; e-mail: caodr@mail.gic.ac.cn
0040-4039/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.05.092

4976
D. Cao, H. Meier / Tetrahedron Letters 46 (2005) 4975–4977
5. Kimura, M.; Sirasu, K.; Okamoto, H.; Satake, K.;
R3
Morosawa, S. Tetrahedron Lett. 1992, 33, 6975–6978.
6. Gan, H.; King, J. L.; Yang, N. C. Tetrahedron Lett. 1989,
30, 1205–1208.
7. Kimura, M.; Kura, H.; Nukada, K.; Okamoto, H.;
Satake, K.; Morosawa, S. J. Chem. Soc., Perkin Trans. 1
1988, 3307–3310.
R2
+
R1
R2
R1
KOH
_
α
CH2
O
+
[(CH3)3C]4N Br
CH2OH
CH2Br
CH2
β
1
2
8. Mak, K. T.; Srinivasachar, K.; Yang, N. C. J. Chem. Soc.,
Chem. Commun. 1979, 1038–1040.
9. Yang, N. C.; Lilman, J. J. Am. Chem. Soc. 1972, 94, 9228–
9229.
R2
R2
R3
3
10. Goldstein, M. J.; Hoffmann, R. J. Am. Chem. Soc. 1971,
93, 6193–6204.
11. Cao, D.; Meier, H. Angew. Chem. 2001, 113, 193–195;
Angew. Chem., Int. Ed. 2001, 40, 186–188.
3
a
H
b
H
c
d
e
R1
R2
R3
OCH3 OCH3
OCH3
OCH2–C6H5 OCH3 OCH3 OCH2–C6H5 OCH2–C6H5
12. 1-(Benzyloxymethyl)naphthalenes: compound 3a: color-
less glass; 1H NMR (CDCl3): d = 4.55 (s, 2H, b-CH2), 4.97
(s, 2H, a-CH2), 5.00 (s, 4H, CH2), 6.54 (t, 1H, aromat. H),
6.62 (d, 2H, aromat. H), 7.28–7.52 (m, 14H, aromat. H),
7.85 (m, 2H, aromat. H), 8.10 (m, 1H, aromat. H); FD
MS: m/z (%) = 460 (100, M+Å). Anal. Calcd for C32H28O3:
C, 83.45; H, 6.13. Found: C, 83.39; H, 6.26. Compound
3b: colorless glass; 1H NMR (C6D6): d = 3.37 (s, 6H,
OCH3), 3.85 (s, 3H, OCH3), 4.42 (s, 2H, b-CH2), 4.89(s,
2H, a-CH2), 6.55 (s, 2H, aromat. H), 7.29(m, 3H, aromat.
H), 7.44 (m, 1H, aromat. H), 7.65 (m, 2H, aromat. H),
8.20 (m, 1H, aromat. H); FD MS: m/z (%) = 338 (100,
M+Å). Anal. Calcd for C21H22O4: C, 74.54; H, 6.55. Found:
C, 74.61; H, 6.65. Compound 3c: colorless crystals, mp
79 °C; 1H NMR (CDCl3): d = 3.79(s, 6H, OCH 3), 3.80 (s,
3H, OCH3), 3.93 (s, 3H, OCH3), 4.52 (s, 2H, b-CH2), 5.06
(s, 2H, a-CH2), 6.55 (s, 2H, aromat. H), 7.24–7.35 (m, 3H,
aromat. H), 7.79(m, 2H, aromat. H), 8.08 (m, 1H,
aromat. H); FD MS: m/z (%) = 368 (100, M+Å). Anal.
Calcd for C22H24O5: C, 71.72; H, 6.57. Found: C, 71.81;
H
OCH3 OCH3
62 58
H
69
OCH2–C6H5
74
Yield [%] 63
18
5
O
R2
R2
8
R3
hν
3d,e
1
R1
15
∆ or hν'
16
9
4d,e (100 %)
∆
O
R1
H
O
R2
R2
R2
R3
R2
H
H
1
R1
H, 6.62. Compound 3d: colorless crystals, mp 88 °C; H
NMR (CDCl3): d = 3.92 (s, 3H, OCH3), 4.53 (s, 2H, b-
CH2), 4.96 (s, 4H, CH2), 5.06 (s, 2H, a-CH2), 6.51 (m, 1H,
aromat. H), 6.61 (m, 2H, aromat. H), 7.27–7.49(m, 13H,
aromat. H), 7.78 (m, 2H, aromat. H), 8.10 (m, 1H,
aromat. H); FD MS: m/z (%) = 490 (100, M+Å). Anal.
Calcd for C33H30O4: C, 80.79; H, 6.16. Found: C, 80.69;
R3
5d,e
6d,e
Scheme 1. Reversible formation of biplanemer 4.
could be realized here for naphthalene–benzene systems.
The entirely reversible process 3d,e ¢ 4d,e represents an
interesting molecular basis for optical switching pro-
cesses or for optical data storage.15
1
H, 6.17. Compound 3e: colorless crystals, mp 102°C; H
NMR (CDCl3): d = 3.92 (s, 3H, OCH3), 4.49(s, 2H, b-
CH2), 5.01 (s, 6H, OCH3), 5.05 (s, 2H, a-CH2), 6.64 (s,
2H, aromat. H), 7.23–7.50 (m, 18H, aromat. H), 7.79(m,
2H, aromat. H), 8.10 (m, 1H, aromat. H); FD MS: m/z
(%) = 597 (100, [M+H+]). Anal. Calcd for C40H36O5: C,
80.51; H, 6.08. Found: C, 80.62; H, 6.05.
Acknowledgements
13. 3-Oxatricyclo[7.6.2.25,8]nonadeca-6,10,12,14,16,18-hexa-
1
enes: Compound 4d: colorless solid, mp 90 °C (dec.); H
We are grateful to the Deutsche Forschungsgemein-
schaft, the Fonds der Chemischen Industrie, the
National Natural Science Foundation of China, and
the Guangdong Natural Science Foundation of China
for financial support.
NMR (C6D6): d = 3.12 (s, 3H, OCH3), 3.20 (ddd,
3J = 10.3 Hz, 4J = 2.2 Hz, 4J = 1.8 Hz, 1H, 8-H), 3.46
(dd, 3J = 10.3 Hz, 3J = 7.7 Hz, 1H, 9-H), 3.50/4.01 (AB,
2J = À11.0 Hz, 2H, 7-OCH2), 3.71/3.97 (AB, 2J =
À8.8 Hz, 2H, 4-H), 4.31 (d, 4J = 1.8 Hz, 1H, 6-H), 4.54
2
(ÔsÕ, 2H, 19-OCH2), 4.60/4.66 (AB, J = À10.3 Hz, 2H, 2-
4
3
H), 4.95 (d, J = 2.2 Hz, 1H, 18-H), 5.08 (d, J = 7.7 Hz,
1H, 17-H), 6.92–7.32 (m, 14H, aromat. H); 13C NMR
(C6D6): d = 43.0, 51.3 (C-8, C-9), 55.0 (OCH3), 57.1, 66.7
(C-1, C-5), 69.8, 70.2, 70.4, 80.7 (C-2, C-4, OCH2), 99.5,
104.3, 108.7, 122.5, 124.9, 125.4, 126.4, 127.9, 128.0, 128.1,
128.4, 128.6, 128.7 (aromat. and olefin. CH), 137.6, 137.7,
146.7, 147.6, 164.8, 165.4, 168.5 (aromat. and olefin. Cq);
FD MS: m/z (%) = 490 (100, M+Å). Anal. Calcd for
C33H30O4: C, 80.79; H, 6.16. Found: C, 80.45; H, 6.15.
Compound 4e: colorless solid, mp 100 °C (dec.); 1H NMR
(C6D6): d = 3.08 (s, 3H, OCH3), 3.37/4.01 (AB,
References and notes
1. Gan, H.; Horner, M. G.; Hrnjez, B. J.; McCormack, T.
A.; King, J. L.; Gasyna, Z.; Chen, G.; Gleiter, R.; Yang,
N. C. J. Am. Chem. Soc. 2000, 122, 12098–12111.
2. Reddy, G. D.; Wiest, O.; Hudlicky, T.; Shapiro, V.;
Gonzalez, D. J. Org. Chem. 1999, 64, 2860–2863.
3. Okamoto, H.; Satake, K.; Kimura, M. Bull. Chem. Soc.
Jpn. 1995, 68, 3557–3562.
4. Okamoto, H.; Kimura, M.; Satake, K.; Morosawa, S.
Bull. Chem. Soc. Jpn. 1993, 66, 2436–2439.
2
2J = À11.0 Hz, 2H, OCH2), 3.73/3.98 (AB, J = À8.8 Hz,

D. Cao, H. Meier / Tetrahedron Letters 46 (2005) 4975–4977
4977
2H, 4-H), 3.76 (d, 3J = 8.1 Hz, 1H, 9-H), 4.34 (s, 1H, 6-H),
4.53–4.65 (m, 4H, 2-H and OCH2), 4.91 (ÔsÕ, 2H, OCH2),
5.02 (s, 1H, 18-H), 5.29(d, 3J = 8.1 Hz, 1H, 17-H), 6.83
(m, 1H, aromat. H), 6.95 (m, 1H, aromat. H), 7.05–7.45
(m, 17H, aromat. H); the correlation of the 1H NMR
signals with certain protons is based on 2D measurements;
13C NMR (C6D6): d = 54.7 (C-9), 55.0 (OCH3), 55.6, 66.7
(C-1, C-5), 69.4, 70.0, 70.5, 70.5, 80.7 (C-2, C-4, OCH2),
86.7 (C-8), 100.4, 104.4, 109.0, 122.4, 125.1, 125.4, 127.1,
127.3, 127.9, 128.0, 128.1, 128.2, 128.4, 128.6, 128.7, 128.8
(aromat. and olefin. CH), 137.4, 137.5, 139.9, 146.8, 147.0,
162.7, 163.6, 168.1 (aromat. and olefin. Cq); FD MS: m/z
(%) = 597 (100, [M+H+]). Anal. Calcd for C40H36O5: C,
80.51; H, 6.08. Found: C, 80.60; H, 6.05.
14. Bouas-Laurent, H.; Castellari, A.; Desvergne, J.-P.; Lap-
ouyade, R. Chem. Soc. Rev. 2000, 29, 43–55, and
references cited therein.
15. The direct photolysis leads to the reverse reaction whereas
the triplet sensitized process causes the formation of cage
compounds by intramolecular [2p+2p]cycloadditions.