Synthesis and structural properties of novel polycyclic aromatic compounds using photo-induced cyclisation of 2,7-di-tert-butyl-4-(phenylethenyl)pyrenes

Article abstract of DOI:10.3184/030823408X338710

Wittig reaction of 2,7-di-tert-butylpyrene-4-carbaldehyde with benzyltriphenylphosphonium salts in the presense of n-BuLi gave 2,7-di-tert-butyl-4-(phenylethenyl)pyrenes, from which naphthalene condensed aromatic compounds, 2,7-di-tert-butyl-dibenzo[ij,no

Full text of DOI:10.3184/030823408X338710

JOURNAL OF CHEMICAL RESEARCH 2008
AUGUST, 457–460
RESEARCH PAPER 457
Synthesis and structural properties of novel polycyclic aromatic
compounds using photo-induced cyclisation of
2,7-di-tert-butyl-4-(phenylethenyl)pyrenes
Arjun Paudel, Jian-yong Hu and Takehiko Yamato*
Department of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi 1, Saga-shi, Saga 840-8502,
Japan
Wittig reaction of 2,7-di-tert-butylpyrene-4-carbaldehyde with benzyltriphenylphosphonium salts in the presense of
n-BuLi gave 2,7-di-tert-butyl-4-(phenylethenyl)pyrenes, from which naphthalene condensed aromatic compounds,
2,7-di-tert-butyl-dibenzo[ij,no]tetraphenes, were obtained by photo-induced cyclisation in the presense of iodine.
Keywords: pyrenes, Wittig reaction, (phenylethenyl)pyrene, photo-induced cyclisation, dibenzo[ij,no]tetraphene
The phenanthrene nucleus is present in a large number
of natural substances, some of them having valuable
chemotherapeutic properties, which has resulted in
considerable efforts being made to synthesise them.1–4 Despite
WKHꢀYDULRXVꢀDSSURDFKHVꢀQRZꢀDYDODEOHꢁꢀWKHUHꢀH[LVWꢀQRꢀHI¿FLHQWꢀ
method for the preparation of phenanthrene annulated pyrenes
at positions 4 and 5 as in 1.
2 in 90% yield. The reaction of 2 and the (4-methoxy-
benzyl)triphenyl-phosphonium chloride 3b with n-butyl-
lithium in THF gave the desired 2,7-di-tert-butyl-4-(4-meth
oxyphenylethenyl)pyrene 4b in 85% yield, whose E/Z ratio
was 80:20. The E/Z ratio of the product was determined by its
NMR spectrum. The E isomer was isolated pure in 65% yield
by silica gel column chromatography and recrystallisation
from hexane. Attempted isolation of the pure Z-isomer failed.
Similarly, (E)-2,7-di-tert-butyl-4-(phenylethenyl)pyrene 4a
was prepared in 85% yield.
On the other hands, since electrophilic substitution of
pyrene occurred at 1, 3, 6, and 8 positions, but not at the
other positions (2, 4, 5, 7, 9, and 10).5–12 Therefore, pyrenes
substituted at the latter positions must be prepared in ways
other than by direct electrophilic substitution of pyrene itself.13
For example, Moyle et al.10 prepared 4,9-diethylpyrene in a
low total yield from ethylbenzene in 14 steps using Friedel–
Crafts tramolecular acylation to construct a pyrene ring.
Thus there is substantial interest in investigating the selective
introduction of substituents at positions 4, 5, 9 and 10 in ways
other than by direct electrophilic substitution of pyrene itself.
We previously reported the TiCl4-catalysed formylation
of 2,7-di-tert-butylpyrene (1) with dichloromethyl methyl
ether using the tert-butyl group as a positional protective
group to afford only 4-monoformylated product, 2,7-di-tert-
butylpyrene-4-carbaldehyde2in90%yield.14,15Thiscompound
2 was a convenient starting material for the preparation of
4,5-naphthalene annulated pyrenes by using photo-induced
cyclisation of 2,7-di-tert-butyl-4-(phenylethenyl)pyrenes. We
report here synthesis and structural properties of novel 4,5-
naphthalene condensed pyrenes, in which the [4]helicene16,17
structures are contained.
The structures of products (E)-4b and (Z)-4b were
determined on the basis of their elemental analyses and spectral
1
data. +ꢀ 105ꢀ VLJQDOVꢀ RIꢀ WKHꢀ ROH¿QLFꢀ SURWRQVꢀ IRUꢀ EꢂROH¿QVꢀ
VKRXOGꢀ EHꢀ REVHUYHGꢀ DWꢀ ORZHUꢀ PDJQHWLFꢀ ¿HOGꢀ ꢃG > 7.4 ppm)
than that of ZꢂROH¿QVꢀ ꢃG < 6.9 ppm).18 1H NMR spectrum
of (E)-4b in CDCl shows a singlet at G 3.88 for methoxy
3
protons, a pair of doublets (Jꢀ ꢀ ꢄꢅꢆꢇꢀ +]ꢈꢀ DWꢀ Gꢀ 7.35, 7.91
SSPꢀIRUꢀROH¿QLFꢀSURWRQVꢁꢀDQGꢀDꢀSDLUꢀRIꢀGRXEOHWVꢀꢃJꢀ ꢀꢉꢆꢊꢀ+]ꢈꢀ
at G 6.99, 7.63 ppm for aromatic protons. The structure of the
(Z)-isomer (Z)-4b is also readily assigned from the smaller
coupling constant (Jꢀ ꢀꢉꢆꢉꢀ+]ꢈꢀWKDQꢀWKDWꢀRIꢀꢃE)-4b (Jꢀ ꢀꢄꢅꢆꢇꢀ
Hz) at GꢀꢋꢆꢄꢊꢁꢀꢋꢆꢊꢌꢀSSPꢀIRUꢀROH¿QLFꢀSURWRQVꢆꢀ)XUWKHUPRUHꢁꢀWKHꢀ
methoxy protons and the aromatic protons are observed much
KLJKHUꢀ¿HOGꢀꢃG 3.62 ppmꢀꢀand G 6.52, 6.85 ppm) than those
of (E)-4b (G 3.88 ppmꢀꢀand Gꢀ6.99, 7.63 ppm) due to the ring
current of the pyrene ring. Also one of the tert-butyl protons
of (Z)-4bꢀ ZDVꢀ REVHUYHGꢀ DWꢀ KLJKHUꢀ ¿HOGꢁꢀ G 1.46 ppm due to
the shielding effect of the aromatic ring. These data strongly
support that the structure of (E)-4b is the (E)ꢂFRQ¿JXUDWLRQꢁꢀ
and the structure of (Z)-4b is the (Z)ꢂFRQ¿JXUDWLRQꢆ
When a solution of (E)-4a and a stoichiometric amount of
iodine in benzene was irradiated with a high-pressure murcury
lamp (400W) at room temperature for 6 h, the photocyclisation
product, 2,7-di-tert-butyldibenzo[ij,no]tetraphene (5a) was
obtained only 20% along with the recovery of the starting
compound. Prolonging the reaction time to 24 h led to an
increase of the yield to 30%. Interestingly, when the irradiation
Results and discussion
The preparation of 2,7-di-tert-butylpyrene-4-carbaldehyde
2 was carried out according to the reported procedure.14,15
Thus, formylation of 1 with dichloromethyl methyl ether in
the presence of titanium tetrachloride occurred selectively at
4-position to afford the corresponding 4-formyl derivative
2
4
Cl2CHOMe
CHO
4
5
TiCl4
in CH2Cl2
rt for 2h
(90%)
7
2
1
Scheme 1
* Correspondent. E-mail: yamatot@cc.saga-u.ac.jp

458 JOURNAL OF CHEMICAL RESEARCH 2008
R
CH2P(Ph)3+ Cl-
a; R= H
R
H
H
H
3
b; R= OMe
H
2
+
BuLi in THF
rt for 6 h
R
(85%)
(65%)
a; R= H
a; R= H
(Z)-4
(E)-4
b; R= OMe
b; R= OMe
7
Irradiation with
9
high pressure Hg lamp
10
(E)-4a,b
O
I2,
Me
in benzene
rt for 6 h
1
2
R13
(76%)
(66%)
a; R= H
5
b; R= OMe
Scheme 2
was carried out at room temperature for 6 h with a stoichiometric
amount of iodine plus a large amount of propylene oxide19,20 in
the absence of air led to an increase of the yield of the desired
cyclisation product 5a to 76%. The propylene oxide prevents
HI from photoreducing double bond. Also absence of air
prevents photooxidative side reactions, such as causing by a
photogenerated oxidant, possibly hydrogen peroxide.
Me
H
Me
Me
Me
CH2P(Ph)3+ Br-
H
3c
2
BuLi in THF
rt for 6 h
(35%)
A similar result was obtained in the case of (E)-4b and 2,7-
di-tert-butyl-13-methoxydibenzo[ij,no]tetraphene 5b was
obtained in 66% yield as light-yellow prisms.
(E)-4c
The structures of products 5a and 5b were determined on
the basis of their elemental analyses and spectral data. Thus,
the structures of 5a and 5b were established on the basis of
7
Irradiation with
9
the base peak molecular ion at m/z 414 and 444 in their mass
high pressure Hg lamp
10
5
4
1
spectrum, respectively. H NMR spectrum of 5b in CDCl
3
O
shows a singlet at G 4.02 ppm for methoxy proton, a pair of
doublets (Jꢀ ꢀꢇꢆꢍꢀ+]ꢈꢀDWꢀGꢀ8.72, 7.98 ppm for H9, H10 protons,
and a pair of doublets (Jꢀ ꢀꢉꢆꢌꢀ+]ꢈꢀDWꢀGꢀ8.03, 8.06 ppm for H4,
H5 protons. Further the 1- and 14-aryl hydrogens can clearly
be seen to be deshielded at G 9.33 ppm (Jꢀ ꢀꢄꢆꢅꢀ+]ꢈꢀDQGꢀꢉꢆꢅꢋꢀ
ppm (Jꢀ ꢀꢎꢆꢊꢀ+]ꢈꢁꢀUHVSHFWLYHO\ꢀE\ꢀWKHꢀDGMDFHQWꢀULQJꢁꢀDꢀFRPPRQꢀ
consequence of the expanded benzene ring.17
I2,
Me
12
Me
1
Me 14
in benzene
rt for 6 h
(24%)
2
5c
Scheme 3
7Rꢀ LQYHVWLJDWHꢀ WKLVꢀ ¿QGLQJꢀ LQꢀ PRUHꢀ GHWDLOꢁꢀ ZHꢀ KDYHꢀ
introduced methyl group at C14 position for dibenzo[ij,no]
tetraphenes which could lead the increased skeletal distortion
like benzo[c]phenanthrenes.17 Thus, the reaction of 2 and
the (3,5-dimethylbenzyl)triphenylphosphonium bromide 3c
with n-butyllithium in THF gave the desired (E)-2,7-di-tert-
butyl-4-(3,5-dimethylphenylethynyl)pyrene (E)-4c in 35%
yield. When a solution of (E)-4c and a stoichiometric amount
of iodine in the presence of propylene oxide in benzene was
irradiated with a high pressure murcury lamp (400W) under
the same conditions as in (E)-4a, the photocyclisation product,
2,7-di-tert-butyl-12,14-dimethyldibenzo[ij,no]tetraphene
Consequently, we have succeeded in preparing a series
of substituted (phenylethenyl)pyrene derivatives and
4
dibenzo[ij,no]tetraphene derivatives 5. The UV spectra of
(phenylethenyl)pyrene derivatives 4 in CH2Cl2 along with
that of 2,7-di-tert-butylpyrene (1) are shown in Fig. 1. The
spectra were recorded in CH2Cl2 in the range of 10–5–10–6
M
concentration. For these (phenylethenyl)pyrene derivatives
4, the spectra are almost identical and three absorption bands
were observed in the range of 285–360 nm. The longest
wavelength S–S* bands of these (phenylethenyl)pyrene
derivatives 4 are bathochromically shifted by 10–20 nm in
comparison with that of 2,7-di-tert-butylpyrene (1) due to
the introduction of the phenylethenyl group. On the other
hand, the increased bathochromic shift of (E)-4b (e.g. 8 nm)
in comparison with that of (E)-4a were observed which are
ascribed to the increased S-electron density on the benzene
ring arising from methoxy group introduced.
1
(5c) was obtained in 24% yield as light yellow prisms. H
NMR spectrum of 5c in CDCl shows a singlet at G 2.30, 2.63
3
ppm for methyl protons, a pair of doublets (Jꢀ ꢀꢇꢆꢍꢀ+]ꢈꢀDWꢀ
Gꢀ8.67, 7.96 ppm for H9, H10 protons, and a pair of doublets
(Jꢀ ꢀꢉꢆꢌꢀ+]ꢈꢀDWꢀGꢀ8.03 ppm for H4, H5 protons. Further, as
expected, the 1-hydrogen H1 and one of the methyl groups at
the 14-position can clearly be seen to be deshielded at G 8.88
ppm (Jꢀ ꢀꢄꢆꢅꢀ+]ꢈꢀDQGꢀG 2.63 ppm, respectively by the adjacent
ring, a common consequence of the expanded benzene ring.17
On the other hand, the UVspectra of dibenzo[ij,no]tetraphene
derivatives 5 in CH2Cl2 are almost identical and four
absorption bands were observed in the range of 280–380 nm.

JOURNAL OF CHEMICAL RESEARCH 2008 459
Fig. 1 Electronic absorption spectra of compounds 4a–c and 1 in dichloromethane at room temperature (before cyclisation).
in deuteriochloroform with Me4Si as an internal reference. UV-vis
spectra were recorded on a Perkin Elmer Lambda 19 UV/VIS/NIR
spectrometer. Mass spectra were obtained on a Nippon Denshi JMS-
HX110A Ultrahigh Performance Mass Spectrometer at 75 eV using
a direct-inlet system. Elemental analyses were performed by Yanaco
MT-5.
The quite different shape in the UV spectrum of 5 in comparison
with those of 1 and 4 are ascribed to the expanded conjugation
of S-electron system by the cyclisation reaction. Interestingly,
the slightly different shape in the UV spectrum of 5cꢀFRQ¿UPVꢀ
the increased non-planarity of the aromatic ring to avoid the
sterically crowding by the overlapping at the C1 proton and the
methyl group at the C14 position leading to an increase of the
strain of these systems.16,17
Materials: Preparation of 2,7-di-tert-butylpyrene-4-carbaldehyde
(2) was previously described.14,15
Typical procedure for Wittig reactions of 2,7-di-tert-butylpyrene-4-
carbaldehyde 2
Conclusions
To a solution of benzyltriphenylphophonium chloride 3a (1.15 g,
3.0 mmol) in THF (15 cm3) was added n-BuLi (1.6 M solution in
hexane) (3.5 cm3, 3.0 mmol) at room temperature. After the solution
was stirred for 10 min, the solution of 2,7-di-tert-butylpyrene-4-
carbaldehyde 2 (342 mg, 1.0 mmol) in THF (15 cm3) was added. The
reaction mixture was stirred at room temperature for 6 h under argon,
and then it was poured into a large amount of ice-water and extracted
with ethyl acetate (100 cm3 u 2). The extract was washed with water
and brine, dried over anhydrous MgSO4, and concentrated under
reduced pressure. The residue was chromatographed over silica gel
(Wako C-300, 200 g) with hexane-ethyl acetate (5:1) as eluent to give
(E)-4a as light-yellow solids. Recrystallisation from hexane afforded
(E)-2,7-di-tert-butyl-4-(phenylethenyl)pyrene (E)-4a (354 mg, 85%)
as light-yellow prisms, m.p. 188–190°C (dec.); GH (CDCl3): 1.59
(9H, s, tBu), 1.60 (9H, s, tBu), 7.34 (1H, t, Jꢀ ꢀꢋꢆꢅꢀ+]ꢁꢀ$UH), 7.40
(1H, d, Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±&+bꢀ CHa–Ar), 7.46 (2H, t, Jꢀ ꢀꢋꢆꢅꢀ+]ꢁꢀ
ArH), 7.70 (2H, d, Jꢀ ꢀꢋꢆꢅꢀ+]ꢁꢀ$UH), 8.03 (2H, s, pyrene–H9,10), 8.06
(1H, d, Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±CHbꢀ &+a–Ar), 8.16 (1H, d, Jꢀ ꢀꢄꢆꢉꢀ+]ꢁꢀ
pyrene–H1), 8.22, 8.25 (2H, each d, J = 1.8 Hz, pyrene–H6,8), 8.29
Weconclude that theWittigreaction of2,7-di-tert-butylpyrene-
4-carbaldehyde with benzyltriphenylphosphonium salts in
the presense of n-BuLi should be useful for the preparation
of 2,7-di-tert-butyl-4-(phenylethenyl)pyrenes 4. Photo-
induced cyclisation in the presense of iodine and propylene
oxide led to the novel expanded S-conjugated systems,
dibenzo[ij,no]tetraphene derivatives 5, in which WKHꢀ ¿UVWꢀ
number of the [n]helicene structures are contained. Further
chemical and structural properties of the present novel
dibenzo[ij,no]tetraphene derivatives 5 are currently under
study in our laboratory.
Experimental
1
All melting points are uncorrected. H NMR spectra were recorded
at 300 MHz on a Nippon Denshi JEOL FT-300 NMR spectrometer
Fig. 2 Electronic absorption spectra of compounds 5a–c in dichloromethane at room temperature (after cyclisation).

460 JOURNAL OF CHEMICAL RESEARCH 2008
(1H, s, pyrene–H5), 8.49 (1H, d, Jꢀ ꢀꢄꢆꢉꢀ+]ꢁꢀS\UHQH±H3); m/z: 416
(M + ). Anal. calcd. for C32H32 (416.60): C, 92.26; H, 7.74. Found: C,
91.78; H, 7.94.
2,7-Di-tert-butyl-13-methoxydibenzo[ij,no]tetraphene (5b): Light-
yellow prisms, m.p. 173–174°C; GH (CDCl3): 1.63 (9H, s, tBu), 1.62
(9H, s, tBu), 4.02 (3H, s, OMe), 7.30(1H, dd, Jꢀ ꢀꢎꢆꢊꢁꢀꢇꢆꢍꢀ+]ꢁꢀ+12),
7.98 (1H, d, Jꢀ ꢀꢇꢆꢍꢀ+]ꢁꢀ+10), 8.02 (1H, d, Jꢀ ꢀꢇꢆꢍꢀ+]ꢁꢀ+11), 8.03,
8.06 (2H, each d, Jꢀ ꢀꢉꢆꢌꢀ+]ꢁꢀ+4,5), 8.18, 8,20 (2H, each d, Jꢀ ꢀꢄꢆꢅꢀ
Hz, H3,6), 8.57(1H, d, Jꢀ ꢀꢎꢆꢊꢀ+]ꢁꢀ+14), 8.72 (1H, d, Jꢀ ꢀꢇꢆꢍꢀ+]ꢁꢀ+9),
8.93 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+8), 9.33 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+1); m/z: 444
(M + ). Anal. calcd. for C33H32O (444.61): C, 89.15; H, 7.25. Found:
C, 89.09; H, 7.26.
Similarly, (E)-4b and (E)-4c were obtained in 65% and 35% yields,
respectively. In the case of 4b, a mixture of (E)-4b and (Z)-4b was
1
obtained in the ratio of 80:20 (determined by H NMR spectrum) in
85% yield. (E)-4b isomer was obtained pure by recrystallisation from
hexane in 65% yield as light-yellow prisms, but several attempts to
obtain (Z)-isomer in pure failed.
(E)-2,7-Di-tert-butyl-4-(4-methoxyphenylethenyl)pyrene (E)-(4b):
(290 mg, 65%) Light-yellow prisms, m.p. 224–226°C; GH (CDCl3):
1.59(18H,s,tBu),3.88(3H,s,OMe),6.99(2H,d,Jꢀ ꢀꢉꢆꢊꢀ+]ꢁꢀ$UH),7.35
(1H, d, Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±&+bꢀ &+a–Ar), 7.63 (2H, d, Jꢀ ꢀꢉꢆꢊꢀ+]ꢁꢀ
ArH), 7.91 (1H, d Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±CHbꢀ &+a–Ar), 8.02 (2H,
s, pyrene–H9,10), 8.15 (1H, d, Jꢀ ꢀꢄꢆꢉꢀ+]ꢁꢀS\UHQH±H1), 8.21 (2H, d,
Jꢀ ꢀ ꢄꢆꢉꢀ +]ꢁꢀ S\UHQH±H6,8), 8.26 (1H, s, pyrene–H5), 8.49 (1H, d,
Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H3); m/z: 446 (M + ). Anal. calcd. for C33H34O
(446.26): C, 88.74; H, 7.67. Found: C, 88.36; H, 7.61.
2,7-Di-tert-butyl-12,14-dimethyldibenzo[ij,no]tetraphene
(5c):
Light-yellow prisms, m.p. 110–111°C; GH (CDCl3): 1.54 (9H, s, tBu),
1.63 (9H, s, tBu), 2.30 (3H, s, Me12), 2.63 (3H, s, Me14), 7.35 (1H, s,
H13), 7.69 (1H, s, H11), 7.96 (1H, d, Jꢀ ꢀꢉꢆꢋꢀ+]ꢁꢀ+10), 8.03 (2H, each
d, Jꢀ ꢀꢉꢆꢌꢀ+]ꢁꢀ+4,5), 8.15, 8.21 (2H, each d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+3,6), 8.26
(1H, each d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+8), 8.67 (1H, d, Jꢀ ꢀꢉꢆꢋꢀ+]ꢁꢀ+9), 8.88 (1H,
d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+1); m/z: 442 (M + ). Anal. calcd. for C34H34 (442.65):
C, 92.26; H, 7.77. Found: C, 92.37; H, 7.64.
(Z)-2,7-Di-tert-butyl-4-(4-methoxyphenylethenyl)pyrene (Z)-(4b):
GH (CDCl3): 1.46 (9H, s, tBu), 1.55 (9H, s, tBu), 3.62 (3H, s, OMe),
6.52 (2H, d, Jꢀ ꢀꢋꢆꢅꢀ+]ꢁꢀ$UH), 6.85 (2H, d, Jꢀ ꢀꢋꢆꢅꢀ+]ꢁꢀ$UH), 7.14 (1H,
d, Jꢀ ꢀꢉꢆꢉꢀ+]ꢁꢀS\UHQH±&+bꢀ &+a–Ar), 7.43 (1H, d Jꢀ ꢀꢉꢆꢉꢀ+]ꢁꢀS\UHQH±
CHbꢀ &+a–Ar), 7.71 (2H, s, pyrene–H5), 7.82 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ
pyrene–H6), 7.98, 8.12 (1H, each d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H9,10), 8.15
(1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H1), 8.23 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H8),
8.36 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H3).
Received 2 May 2008; accepted 25 June 2008
Paper 08/5255 doi: 10.3184/030823408X338710
Published online: 21 August 2008
References
1
C.S. Wood and F.B. Mallory, J. Org. Chem., 1964, 29, 3373.
F.B. Mallory, C.S. Wood and J.T. Goedon, J. Am. Chem. Soc., 1964, 86,
3094.
2
(E)-2,7-Di-tert-butyl-4-(3,5-dimethylphenylethenyl)pyrene
(E)-(4c): (128 mg, 35%) Light-yellow prisms, m.p. 141–142°C;
GH (CDCl3): 1.58 (9H, s, tBu), 1.59 (9H, s, tBu), 2.41 (6H, s, Me), 7.00
(1H, s, ArH), 7.31 (2H, s, ArH), 7.32 (1H, d, Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±&+b
&+a–Ar), 8.00 (1H, d Jꢀ ꢀꢄꢅꢆꢇꢀ+]ꢁꢀS\UHQH±&Hbꢀ &+a–Ar), 8.028,
8.031 (2H, each s, pyrene–H9,10), 8.16 (1H, d, Jꢀ ꢀꢄꢆꢉꢀ+]ꢁꢀS\UHQH±
H1), 8.21 (2H, d, Jꢀ ꢀꢄꢆꢉꢀ+]ꢁꢀS\UHQH±H6,8), 8.25 (1H, s, pyrene–H5),
8.48 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀS\UHQH±H3); m/z: 444 (M + ). Anal. calcd. for
C34H36 (444.66): C, 91.84; H, 8.16. Found: C, 91.63; H, 8.25.
3
L. Castedo, J.M. Saá, R. Suau and G. Tojo, Tetrahedron Lett., 1983, 24,
5419.
4
5
A.J. Floyd, S.F. Dyke and S.E. Ward, Chem. Rev., 1976, 76, 509.
A. Bjørseth and T. Ramdahl, Handbook of polycyclic aromatic
hydrocarbons, eds. A. Bjørseth and T. Ramdahl, Marcel Dekker, New
York, 1985, p. 1.
6
7
E. Cavalieri and E. Rogan, Environ. Health Perspect., 1985, 64, 69.
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II.
8
9
H. Vollmann, H. Becker, M. Correl and H. Streeck, Justus Liebigs Ann.
Chem., 1937, 531, 1.
Photo-irradiation of 4a: typical procedure
2,7-Di-tert-butyl-4-(phenylethenyl)pyrene 4a (50 mg, 0.119 mmol),
I2 (28.3 mg, 0.12 mmol) and propylene oxide (1.53 cm3, 21.1 mmol)
was dissolved in benzene (260 cm3), and the solution was irradiated
with a high-pressure Hg lamp (400 W) for 6 h. The reaction mixture
was poured into ice-water (300 cm3) and extracted with ethyl acetate
(50 cm3 u 3). After the ethyl acetate solution had been washed
successively with 10% sodium thiosulfate, water and brine the
extract was dried over anhydrous sodium sulfate and concentrated.
The residue was washed with methanol (10 cm3) to afford 2,7-di-tert-
butyl-dibenzo[ij,no]tetraphene 5a (37.6 mg, 76%) as light-yellow
prisms, m.p. 163–165°C; GH (CDCl3): 1.62 (9H, s, tBu), 1.64 (9H, s,
tBu), 7.65–7.68 (2H, m, H12,13), 8.05, 8.06 (2H, each d, Jꢀ ꢀꢉꢆꢌꢀ+]ꢁꢀ
H4,5), 8.08 (1H, d, Jꢀ ꢀꢅꢆꢋꢀ+]ꢁꢀ+11), 8.09 (1H, d, Jꢀ ꢀꢇꢆꢍꢀ+]ꢁꢀ+10),
8.21, 8.23 (2H, each d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+3,6), 8.86 (1H, d, Jꢀ ꢀꢇꢆꢍꢀ+]ꢁꢀ
H9), 8.95 (1H, d, Jꢀ ꢀꢄꢆꢅꢀ+]ꢁꢀ+8), 9.16 (1H, dd, Jꢀ ꢀꢄꢆꢎꢁꢀꢋꢆꢉꢀ+]ꢁꢀ+14),
9.27 (1H, d, Jꢀ ꢀꢄꢆꢎꢀ+]ꢁꢀ+1); m/z: 414 (M + ). Anal. calcd. for C32H30
(414.58): C, 92.71; H, 7.29. Found: C, 92.78; H, 7.49.
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Similarly, 5b and 5c were obtained in 66 and 24% yields,
respectively.
20 I. Ben, L. Castedo, J.M. Saá, J.A. Seijas, R. Suau and G. Tojo, J. Org.
Chem., 1985, 50, 2236.