Synthesis of dibenzopyrenes and pyrenes via photolytic sulfur extrusion and intramolecular cross-coupling reactions of dithia[3.3] (1,3)naphthalenophanes and dithia[3.3]metacyclophanes

Article abstract of DOI:10.1021/jo970181w

The syntheses of several substituted dithia[3.3]metacyclophanes and dithia[3.3](1,3)naphthalenophanes are reported and their photolyses in triethyl or trimethyl phosphite are described. Under these conditions, the corresponding tetrahydrodibenzopyrenes and tetrahydropyrenes are produced in a one-pot procedure when the precursor dithianaphthalenophanes and dithiacyclophanes possess at least one intraannular methoxyl group. A mechanism with supporting evidence is proposed to account for these results. Structural determinations of the four isomeric 11,22-dimethoxy-2,13- dithia[3.3](1,3)naphthalenophanes by NMR and X-ray single-crystal diffraction studies are also described. The syntheses of the novel anti-transoid- and anti-cisoid-[2.2](1,3)naphthalenophanes are also described.

Full text of DOI:10.1021/jo970181w

6476
J . Org. Chem. 1997, 62, 6476-6484
Syn th esis of Diben zop yr en es a n d P yr en es via P h otolytic Su lfu r
Extr u sion a n d In tr a m olecu la r Cr oss-Cou p lin g Rea ction s of
Dith ia [3.3](1,3)n a p h th a len op h a n es a n d
Dith ia [3.3]m eta cyclop h a n es
Muhammad Ashram,† David O. Miller,‡ J ohn N. Bridson,‡ and Paris E. Georghiou*,†
Department of Chemistry and X-ray Crystallographic Unit, Memorial University of Newfoundland,
St. J ohn’s, Newfoundland, Canada A1B 3X7
Received J anuary 30, 1997X
The syntheses of several substituted dithia[3.3]metacyclophanes and dithia[3.3](1,3)naphthalenophanes
are reported and their photolyses in triethyl or trimethyl phosphite are described. Under these
conditions, the corresponding tetrahydrodibenzopyrenes and tetrahydropyrenes are produced in a
one-pot procedure when the precursor dithianaphthalenophanes and dithiacyclophanes possess at
least one intraannular methoxyl group. A mechanism with supporting evidence is proposed to
account for these results. Structural determinations of the four isomeric 11,22-dimethoxy-2,13-
dithia[3.3](1,3)naphthalenophanes by NMR and X-ray single-crystal diffraction studies are also
described. The syntheses of the novel anti-transoid- and anti-cisoid-[2.2](1,3)naphthalenophanes
are also described.
In connection with our ongoing research into the
minations of the isomeric dithianaphthalenophanes 3-6
and the novel [2.2](1,3)naphthalenophanes 41 and 42.
chemistry of the calixnaphthalenes1,2 and their ana-
logues,3 we were interested in the synthesis of tetrahomo-
calix[4]naphthalene (1) and its structural isomers. The
synthetic approach which we employed was similar to
that used for the synthesis of (1,3)dihomocalix[4]naph-
thalenes.3 The latter compounds, which are the first
[1.2.1.2](1,3)naphthalenophanes to be reported, were
obtained via a final photolytic sulfur extrusion reaction
in triethyl phosphite. Such photolytic sulfur extrusion
reactions have also been used by others to synthesize
cyclophanes.4,5 During attempts to produce the tetra-
thia[3.3.3.3](1,3)naphthalenophane (2), which is the po-
tential precursor to 1, the four isomeric 11,22-dimethoxy-
2,13-dithia[3.3](1,3)naphthalenophanes (3-6) were ob-
tained. These products are analogous to the corresponding
11,22-dimethyl- and 11,22-unsubstituted-2,13-dithia-
[3.3](1,3)naphthalenophanes (13-16) reported by Mitch-
ell et al.6 However, when each of the compounds 3-6
was photolyzed in triethyl or trimethyl phosphite, tet-
rahydro-3,4:8,9-dibenzopyrene (7) or tetrahydro-3,4:9,10-
dibenzopyrene (8) was obtained instead of the expected
corresponding naphthalenophane. Facile oxidation of
these tetrahydro compounds produced dibenzopyrenes 9
and 10, respectively. In this paper we report that this
type of sulfur extrusion with concomitant transannular
cyclization appears to be a general one which could offer
some advantages for the synthesis of dibenzopyrenes and
pyrenes. A mechanism is proposed to account for the
observed results. We also describe the structural deter-
Resu lts a n d Discu ssion
Base-mediated coupling of bis(bromomethyl)methoxy-
naphthalene 11 with bis(mercaptomethyl)methoxynaph-
thalene 12 produced a mixture which, after preparative
layer chromatographic (PLC) separation, afforded four
isomeric 11,22-dimethoxy-2,13-dithia[3.3](1,3)naphthaleno-
phanes (3-6) in 10%, 18%, 34% and 19% yields, respec-
tively (Scheme 1). Isomer 3 was the least polar, followed
by 4, 5, and 6 being increasing more polar. A fifth
fraction was also isolated (17%) whose spectral properties
(NMR and FAB MS) were distinctly different from those
of any of the compounds 3-6. This fraction, which is
homogeneous on TLC, appears to be a mixture of possibly
all four isomeric tetrathia[3.3.3.3](1,3)naphthalenophanes.
Work is presently ongoing on this fraction with results
to be published in a forthcoming paper.
1
The H NMR spectrum of 3 has well-resolved signals
with simple splitting patterns (as do, to varying degrees,
the spectra of each of the other isomers 4-6) that are
consistent with a transoid-anti structure.6 Support for
the NMR assignments (of this and the other isomers,
Figure 1) is based upon 2-D and NOED experiments and
by comparison with arguments presented by Mitchell et
al.6 for their closely related compounds 13-16. The
methoxyl groups of 3 at δ ) 2.93 are shielded by 0.64
ppm relative to those of its syn isomer 5. The bridging
methylene protons of 3 are diasteretopic and appear as
two sets of AB quartets, one which is poorly resolved and
is centered at δ ) 3.26. Since H-5 (H-16) is the only
naphthalene-ring singlet, it was used as the reference
signal together with NOED determinations to unequivo-
cally assign the remaining naphthalene-ring protons H-6
to H-9 (H-16 to H-20) and also the remainder of the
protons. The AB quartet at δ ) 3.26 is attributed to the
H-3 (and H-14) protons since irradiation of this system
produces a 5.6% NOED enhancement of the H-5 (and
H-16) singlet and also a 2.4% NOED enhancement of the
doublet at δ ) 8.18 which is due to H-20 (and H-9).
Molecular models indicate that H-20 and H-9 can only
† Department of Chemistry.
‡ X-ray Crystallographic Unit.
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) Georghiou, P. E.; Li, Z. Tetrahedron Lett. 1993, 34, 2887.
(2) Georghiou, P. E.; Ashram, M.; Li, Z.; Chaulk, S. G. J . Org.Chem.
1995, 60, 7284.
(3) Georghiou, P. E.; Li, Z.; Ashram, M.; Miller, D. O. J . Org.Chem.
1996, 61, 3865.
(4) Boekelheide, V.; Reingold, I. D.; Tuttle, M. J . Chem. Soc. Chem.
Commun. 1973, 406.
(5) Yamato, T.; Miyazawa, A.; Tashiro, M. Chem. Ber. 1993, 126,
2505.
(6) Mitchell, R. H.; Williams, R. V.; Dingle, T. W. J . Am. Chem. Soc.
1982, 104, 2560; see also Mitchell, R. H. In Cyclophanes; Academic
Press, New York, 1983; Vol. 1.
S0022-3263(97)00181-3 CCC: $14.00 © 1997 American Chemical Society

Synthesis of Dibenzopyrenes and Pyrenes
J . Org. Chem., Vol. 62, No. 19, 1997 6477
Sch em e 1
Sch em e 2
be in close proximity to H-3x and H-14x, respectively,
when the intraannular 12-membered dithia ring is in a
conformation with S-2 pointing down and S-13 pointing
up, as indicated in Figure 1. This is in agreement with
the conformation proposed by Mitchell et al.6 for the
analogous compound anti-14. The other AB quartet has
two clearly defined doublets; one centered at δ ) 4.00 (J
) 11.7 Hz; H-1y and H-12y; pseudo-equatorial7) which
is NOED-enhanced by 6.2% when H-9 is irradiated, and
the other at δ ) 4.33 (J ) 11.7 Hz; H-1x and H-12x;
pseudo-axial7), which is not. A single crystal X-ray
diffraction analysis on 3 (Figure 2) confirms the struc-
tural assignments and indicates that the preferred
conformation in the solid state is the same as that in
solution. Molecular modeling calculations8 are also
consistent with the conformational assignment depicted
in Figure 1.
Unequivocal chemical proof of the transoid structure
of 3 (and of 5 and also of the cisoid structures of isomers
4 and 6; see below) was obtained unexpectedly from its
photolysis in triethyl phosphite,4 which produced, instead
of the anticipated naphthalenophane 17, a product whose
NMR spectra showed it to be highly symmetrical and
lacking the methoxyl groups. Mass spectral data indi-
cated, and single crystal X-ray crystallography (Figure
3) confirmed, it to be 1,2,6,7-tetrahydro-3,4:8,9-diben-
zopyrene (7). DDQ oxidation easily converted 7 to 3,4:
8,9-dibenzopyrene (9).9
1
The methoxyl groups in the H NMR spectrum of the
(7) In this paper, “pseudo-axial” protons refer to bridging methylene
group protons which are in, or are directed toward, the planes of the
naphthalene rings; “pseudo-equatorial” protons refer to bridging
methylene group protons which are out of, or are directed out of, the
planes of the rings.
syn isomer 5 are at δ ) 3.57, which is more typical for
an unshielded 2-naphthyl methoxyl group (δ ) 3.92 in
(9) Clar, E. Polycyclic Hydrocarbons, Academic Press, London, 1964;
Vol. II.
(8) SPARTAN, version 4.1, Wavefunction, Inc., Irvine, CA.

6478 J . Org. Chem., Vol. 62, No. 19, 1997
Ashram et al.
of the C-1-S-2-C-3 bridge which would place the S-2-
C-3-C-4 bonds in a nearly coplanar arrangement with
the C-4-C-11 naphthalene ring (in dynamic equilibrium
with the conformation which places S-2-C-1-C-21 bonds
in a nearly coplanar arrangement with the C-21-C-22
naphthalene ring). Since only H-9 (H-16) is NOED
enhanced when H-12y (H-14y) is irradiated, the other (C-
12-S-13-C-14) bridge cannot be similarly skewed. This
is also in general agreement with the interpretations
made without any such NOED data, by Mitchell et al.
1
for the H-NMR spectra of their analogous anti-16.
The line shapes and chemical shifts for the bridging
methylene protons in the cisoid-syn compound 6 are
similar to those observed in the transoid-syn isomer 5.
In 6, one AB quartet has a doublet centered at δ ) 5.00
(J ) 14.7 Hz) assigned to H-12x (and H-14x), which is
coupled to the doublet centered at δ ) 3.83 (H-12y,
H-14y). The other AB quartet due to the protons on C-1
(and C-3) has a doublet centered at δ ) 4.54 (J ) 15.0
Hz) assigned to H-1x (and H-3x) and its coupled doublet
at δ ) 3.60 assigned to H-1y (and H-3y). Mitchell et al.
assigned a preferred conformation to the analogous
compound syn-16 in which they postulated that, in order
to minimize the peri interactions between the methylene
bridge protons and the protons on the A-rings (H-5 and
H-20 in 6), the C-1-S-2-C-3 bridge should be pointing
up and the C-12-S-13-C-14 bridge pointing down in a
boat-chair type of conformation. NOED determinations
did not permit distinguishing unequivocally between such
a boat-chair type of conformation and one in which both
bridges are pointing down in a chair-chair type of
conformation. Molecular modeling calculations however
clearly indicate that the latter is energetically favored
(by 6.35 kcal/mol). Also, the optimized geometries of the
two conformations reveal that the distance between H-3y
and H-5 (the peri interaction referred to above) is only
2.40 Å in the boat-chair but 2.71 Å in the chair-chair
conformation.
1
F igu r e 1. Selected H δ values and preferred conformations
of compounds 3-6.
2-methoxynaphthalene, and δ ) 3.86 in bis(2-methoxy-
1-naphthyl)methane). The bridging methylene protons
are diasteretopic and appear as two sets of AB quartets
each having a pair of clearly defined doublets. One AB
quartet has a doublet centered at δ ) 4.84 (J ) 13.5 Hz)
assigned to H-1x and H-12x which is coupled to the
doublet centered at δ ) 3.84 assigned to hydrogens H-1y
and H-12y. The other AB quartet, assigned to the H-3x
(and H-14x) protons, has a doublet centered at δ ) 4.59
(J ) 16.4 Hz) which is coupled to the doublet at δ ) 3.51
(H-3y; H-14y). The transoid hydrogens H-5 and H-16 are
eclipsed by the opposing naphthalene rings and thus
appear as a singlet at δ ) 6.96 which is shielded by 1.16
ppm compared to the corresponding signal in 3. The
conformational assignment shown is further supported
by NOED determinations and molecular modeling cal-
culations. For example, there is NOED enhancement of
H-1x (H-12x) by H-3x (H-14x) and vice versa. Photolysis
of 5 under the conditions employed for 3 also produced
7, but no 17.
Photolysis of either 4 or 6, under the same conditions
employed for 3, and 5 produced only 1,2,6,7-tetrahydro-
3,4:9,10-dibenzopyrene (8) and no 10,20-dimethoxy(1,3)-
naphthalenophane (18). DDQ oxidation of 8 afforded 3,4:
9,10-dibenzopyrene (10). Both of the isomeric benzopy-
renes 9 and 10 had identical physical properties with
those previously reported.9
We are unaware of any other reports of similar one-
pot sulfur extrusion/transannular cyclizations from 2,13-
dithia[3.3]naphthalenophanes or 2,11-dithia-[3.3]cyclo-
phanes leading to either tetrahydrodibenzopyrenes or
tetrahydropyrenes, respectively. Boekelheide et al.4 first
reported the photochemical transformation in trimethyl
phosphite of 6-methyl- and 9-methyl-2,11-dithia[3.3]cyclo-
phane to the corresponding [2.2]metacyclophanes but did
not report the formation of any of the corresponding
pyrenes. Earlier, Mitchell and Boekelheide10 had re-
ported the transformation of 9,18-dimethyl-2,11-dithia-
[3.3]metacyclophanes into the corresponding 15,16-di-
methyldihydropyrene, but the sequence involved several
steps including a Stevens rearrangement and an elimi-
nation step. On the other hand, there are many ex-
amples that have been reported in which halogen-
induced11-13 and photolytically induced14 transannular
The 1H NMR spectrum of 4 is consistent with its cisoid-
anti structure. The methoxyl groups of 4 are at δ ) 2.92
indicating shielding by 0.64 ppm relative to those of its
cisoid-syn isomer 6. The bridging methylene protons
appear as two overlapping sets of AB quartets whose
respective pairs of coupled doublets are centered at δ )
4.05 (J ) 13.8 Hz; H-12x, H-14x) and δ ) 3.88 (H-12y,
H-14y); and at δ ) 3.89 (J ) 13.8 Hz, H-1x, H-3x) and δ
) 3.62 (H-1y, H-3y). The singlet at δ ) 7.88 due to the
cisoid hydrogens H-5 and H-20 is deshielded relative to
the corresponding signal (at δ ) 7.46) for 6. NOED
experiments on 4 reveal that irradiation of either H-3x
(H-1x) or H-3y (H-1y) enhances H-5 (H-20) by 1.9% and
1.4%, respectively. However, irradiation of only H-12y
(H-14y) enhances H-9 (H-16) by 7.7%. Irradiation of
H-12x (H-14x) does not enhance H-9 (H-16). To account
for these NMR observations, the preferred conformation
appears to be one in which there is, on average, a skewing
(10) Mitchell, R. H.; Boekelheide, V. Tetrahedron Lett. 1970, 1197;
Mitchell, R. H.; Boekelheide, V. J . Am. Chem. Soc. 1974, 96, 1547.
(11) Sato, T.; Nishiyama, K.; Murai, A. J . Chem. Soc. Chem.
Commun. 1972, 163.

Synthesis of Dibenzopyrenes and Pyrenes
J . Org. Chem., Vol. 62, No. 19, 1997 6479
F igu r e 2. Stereoview of 3.
produce the tetrahydropyrenes 33-35. At least one
intraannular methoxyl group therefore appears to be
necessary to allow for the in situ transannular cyclization
step. The presence of an electron-withdrawing group at
the 6- or 15-position, e.g. bromine in the case of 30,
however, appears to inhibit the sulfur elimination/
intrannular cyclization. It can be noted that Yamato and
co-workers13 have reported the cyclization of various
substituted 8-methoxy[2.2]metacyclophanes themselves
to the corresponding tetrahydropyrenes using benzyltri-
methyl ammonium tribromide (BTMA-Br3). However, in
agreement with our findings with 30, they too were
unable to effect cyclization when a bromine atom or other
electron-withdrawing groups were present in the para-
positions (R2 or R4, in Scheme 4). DDQ oxidation easily
converted 33-35 into the corresponding pyrenes.
To further support our findings, dithia[3.3](1,3)naph-
thalenophanes 37 and 38, in which the methoxyl groups
are situated at the 5- and 16- positions and the 5- and
20-positions, respectively, were synthesized and subjected
to the same photolytic conditions. Synthesis of 37 and
38 was achieved by the base-mediated coupling of 39 and
40 (Scheme 4). It was possible by repeated PLC separa-
tion to obtain small amounts of the less polar transoid-
anti-dithianaphthalenophane 37 in a pure enough state
to enable it to be unambiguously characterized. Cisoid-
anti-38 however, was always contaminated with small
amounts of 37. That 37 and 38 are conformationally
more mobile than 3-6 is evident by the fact that the
bridging methylene protons appear as sharp singlets in
F igu r e 3. ORTEP diagram of X-ray structure of 7.
cyclization of various [2.2]metacyclophanes produce the
corresponding tetrahydropyrenes. However, all of these
instances involve prior formation of the cyclophanes from
the precursor dithiaphanes, a process which usually
requires two separate steps involving oxidation of the
disulfides to the bissulfones, followed by a vacuum
pyrolysis.
1
their respective ambient temperature H NMR spectra.
Photolysis of PLC-purified fractions which contained a
mixture of 37 and 38 afforded two easily separable
products whose spectral properties are consistent with
the novel transoid-anti and cisoid-anti-[2.2](1,3)naph-
thalenophane structures 41 and 42, respectively. These
are the first [2.2](1,3)naphthalenophanes to be reported.
In light of the previous discussions, 37 is most likely the
precursor of 41, and 38 the precursor of 42. That both
compounds are anti is evident by the fact that the
intraannular protons appear upfield at δ ) 4.51 in both
cases. Although the chemical shifts for the ethano bridge
protons in both compounds are nearly identical, their line
shapes are dramatically different. In 42 they appear as
two distinct AX systems, centered at δ ) 3.97 and 2.01
(J ) 10.1 Hz) and at δ ) 3.72 and 2.16 (J ) 9.0 Hz),
whereas in 41 they appear as two AMPX multiplets, one
set of signals consisting of a doublet of triplets centered
at δ ) 3.95 which is coupled to a triplet of doublets
centered at δ ) 2.24 and the second set consisting of a
doublet of triplets centered at δ ) 3.72 which is coupled
to a triplet of doublets centered at δ ) 2.00. No
transannular cyclized products were detected from the
photolyses.
In order to ascertain whether our observation on the
photolyses of compounds 3-6 was a general one, we
examined the reactions leading to the dithia[3.3]metacyclo-
phane precursors 26-30 of the tetrahydropyrenes 33-
36, respectively, as summarized in Scheme 3. Boekel-
heide et al.4 had not observed any cyclization during the
photolytic sulfur elimination reaction of dithiacyclophane
31, in which only hydrogen atoms are present at both
the 9- and 18-positions, or 32, in which a methyl group
and a hydrogen atom are present at the 9- and 18-
positions, respectively. The reactions of dithia[3.3]-
metacyclophanes 26-30, in which at least one methoxyl
group was present at these intraannular positions, were
therefore examined. Intermediate compounds 20-25
were all synthesized and coupled by standard procedures
to give the corresponding dithiacyclophanes 26-30 in
good yields. Photolytic sulfur elimination/intraannular
cyclization occurred in all cases, except with 30, to
(12) Sato, T.; Wakabayashi, M.; Okamura, T.; Amada, T.; Hata, K.
Bull. Chem. Soc. J pn. 1967, 40, 2363.
(13) Yamato, T.; Ide, S.; Tokuhisa, K.; Tashiro, M. J . Org. Chem.
1992, 57, 271 and references cited therein.
(14) Sato, T.; Wakabayashi, M.; Hayashi, S.; Hata, K. Chem. Soc.
J pn. 1969, 42, 773.
The mechanism depicted in Scheme 5 is consistent
with the results found for a typical example in which

6480 J . Org. Chem., Vol. 62, No. 19, 1997
Ashram et al.
Sch em e 3
Sch em e 4
photolytic sulfur elimination/intrannular cyclization re-
action did occur. Thus, when the photolysis of 5 was
interrupted after 7 h, three new products in addition to
7 were isolated and characterized. These were, in order
of increasing polarity, 7 and the three intermediate
compounds anti-dimethoxy[2.2](1,3)naphthalenophane
(17a ), monothia compound 43, and the syn-dimethoxy-
[2.2](1,3)naphthalenophane (17b), which convert to 7
upon further photolysis.
In conclusion, we have observed that the photolysis in
trimethyl or triethyl phosphite solution of various sub-
stituted dithiacyclophanes which possess either one or
two intraannular methoxyl groups can produce, in a
single step, the corresponding tetrahydropyrenes. Simi-
larly, the photolysis of similar intraannularly substituted
methoxydithia[3.3](1,3)naphthalenophanes produced, in
a single step, the corresponding tetrahydrodibenzopy-
renes. Photolysis of 5,16-dimethoxy and 5,20-dimethoxy-
2,13-dithia[3.3](1,3)naphthalenophanes (37 and 38) af-
forded the anticipated 4,14-dimethoxy- and 4,18-dimeth-
oxy[2.2]naphalenophanes 41 and 42, respectively.
Exp er im en ta l Section
Gen er a l Meth od s. For general experimental data, see ref
2. 1H-NMR and 13C-NMR spectra were recorded at 300 and
75.47 M Hz, respectively in CDCl3 unless otherwise noted. All
photochemical reactions were conducted in a Rayonet photo-
chemical reactor. Where compounds have been reported by
others, only the spectral data which have not previously been
reported are presented here.
1,3-Bis(br om om eth yl)-2-m eth oxyn a p h th a len e (11). To
a solution of 2-(hydroxymethyl)-3-methoxynaphthalene (14.1
g, 11.7 mmol) and paraformaldehyde (4.54 g, 150 mmol) in
200 mL of glacial acetic acid was added a 10% solution (200
mL) of HBr in glacial acetic acid. After stirring for 36 h, a
precipitate formed which was filtered and washed several
times with petroleum ether to afford 7.44 g of a colorless

Synthesis of Dibenzopyrenes and Pyrenes
J . Org. Chem., Vol. 62, No. 19, 1997 6481
Sch em e 5
powder. The filtrate was diluted with CH2Cl2 (200 mL) and
washed several times with water and finally with aqueous
saturated NaHCO3 solution until the washes were neutral. The
organic layer was dried over MgSO4 and the solvent evapo-
rated on a rotary evaporator. The residue was washed with
several portions of diethyl ether to give another 5.18 g of the
crude product. The combined product (12.64 g; 49%), mp 114-
116 °C, was used directly in subsequent steps, without further
purification: 1H-NMR δ 4.14 (s, 3H), 4.72 (s, 2H), 5.05 (s, 2H),
7.51-7.46 (m, 1H), 7.65-7.60 (m, 1H), 7.82 (d, J ) 7.8 Hz 1H),
7.94 (s, 1H), 8.08 (d, J ) 8.4 Hz, 1H). 13C-NMR δ 24.69, 28.23,
62.35, 123.48, 125.28, 125.79, 127.56, 127.69, 128.63, 130.92,
132.44, 132.70, 154.70; MS m/ z (%) 344 (16), 342 (9), 266 (14),
265 (100), 264 (14.5), 263 (96.5), 235 (13), 233 (15), 183 (13),
169 (17.5), 156 (24), 155 (90), 154 (20), 153 (19.5), 152 (13),
141 (32); HRMS M+ 341.9250, calcd for C13H12Br2O 341.9255.
1,3-Bis(m er ca p tom eth yl)-2-m eth oxyn a p h th a len e (12).
A solution of 11 (0.41 g, 1.2 mmol) and thiourea (0.22 g, 2.9
mmol) in 25 mL of DMSO was stirred at room temperature
under Ar for 5 h. The mixture was poured into 50 mL of
aqueous 10% NaOH which was cooled in an ice bath. The
reaction mixture was stirred for an additional 2 h at room
temperature, under Ar, and then cooled in an ice bath, and
aqueous 4 N HCl was added until the solution become acidic.
The reaction mixture was extracted twice with 30-mL portions
of CH2Cl2. The combined organic layer was washed with two
20-mL portions of H2O and then with three 20-mL portions of
aqueous saturated NaCl. After drying over anhydrous MgSO4,
filtering, and evaporating the solvent, the crude product was
flash chromatographed using CH2Cl2:petroleum ether (50:50)
to give 0.21 g (0.84 mmol, 70%) of 12 as an oil: 1H-NMR δ
1.97 (t, 1H), 1.99 (t, 1H), 3.89 (d, J ) 7.8 Hz, 2H), 3.99 (s, 3H),
4.22 (d, J ) 6.9 Hz, 2H), 7.54-7.39 (m, 2H), 7.73 (s, 1H), 7.76
(d, J ) 7.8 Hz 1H), 7.96 (d, J ) 8.4 Hz 1H); 13C-NMR δ 19.23,
24.13, 62.63, 123.30, 125.58, 126.58, 128.36, 128.48, 128.83,
131.26, 134.21; MS m/ z (%) 250 (75, M+), 218 (16), 217 (100),
172 (19), 171 (99), 143 (17.5), 141 (23); HRMS M+ 250.0467,
calcd for C13H14S2O 250.0485.
CH2Cl2 (50 mL) and the organic solution was washed with
portions of aqueous 10% HCl until the aqueous layers become
acidic. The organic layer was dried over anhydrous MgSO4
and filtered, and the solvent was evaporated on a rotary
evaporator. A portion of the crude product (250 mg) was
chromatographed by PLC using CH2Cl2:petroleum ether (60:
40) to give five fractions in the following order of increasing
polarity:
tr a n soid -a n ti-11,22-Dim et h oxy-2,13-d it h ia -[3.3](1,3)-
n a p h th a len op h a n e (3) was obtained as a colorless crystal-
line compound (from CHCl3, chlorobenzene, or toluene) (25
1
mg): mp 268-270 °C; H-NMR δ 2.93 (s, 6H), 3.26 (m, 4H),
4.0 (d, J ) 11.7 Hz, 2H), 4.33 (d, J ) 11.7 Hz, 2H), 7.44 (m,
2H), 7.54 (m, 2H), 7.86 (d, J ) 7.8 Hz, 2H), 8.12 (s, 2H), 8.18
(d, J ) 8.4 Hz, 2H); 13C-NMR δ 22.89, 25.88, 61.10, 119.81,
123.1, 124.44, 126.10, 128.27, 131.11, 131.29, 131.48, 132.50,
156.68; MS m/ z (%) 432 (6, M+), 368 (11), 218 (10), 217 (17),
216 (14), 215 (12), 186 (45), 185 (100), 183 (14), 171 (19). 155
(54); HRMS M+ 432.1193, calcd for C26H24S2O2 432.1216.
ci soi d -a n t i -11,22-D im e t h o x y -2,13-d it h ia [3.3](1,3)-
n a p h th a len op h a n e (4) was obtained as a colorless powder
(37 mg): mp 123-125 °C; 1H-NMR δ 2.93 (s, 6H), 3.62 (d, J )
13.8 Hz, 2H), 3.88 (d, J ) 13.8 Hz, 2H), 3.89 (d, J ) 13.8 Hz,
2H), 4.05 (d, J ) 13.8 Hz, 2H), 7.43 (m, 2H), 7.53 (m, 2H),
7.81 (d, J ) 7.8 Hz, 2H), 7.88 (s, 2H), 8.31 (d, J ) 8.4 Hz, 2H)
;
13C-NMR δ 24.05 , 26.6, 61.18, 121.98, 123.86, 124.33, 125.60,
128.02, 128.97, 131.57, 133.03, 156.37; MS m/ z (%) 432 (100,
M+), 247 (29), 217 (18), 216 (61), 215 (58), 214 (39), 201 (17),
186 (28), 185 (47), 184 (17), 183 (17), 171 (20), 167 (22), 155
(37); HRMS M+ 432.1213, calcd for C26H24S2O2 432.1216.
Tr a n soid -syn -11,22-d im e t h oxy-2,13-d it h ia [3.3](1,3)-
n a p h th a len op h a n e (5) was obtained as a colorless crystal-
line powder (52 mg): mp 208-209 °C; 1H-NMR δ 3.51 (d, J )
16.4 Hz, 2H), 3.57 (s, 6H), 3.84 (d, J ) 13.5 Hz, 2H), 4.59 (d,
J ) 16.4 Hz, 2H), 4.84 (d, J ) 13.5 Hz, 2H), 6.75 (d, J ) 7.8
Hz, 2H), 6.96 (s, 2H), 7.04 (m, 2H), 7.37 (m, 2H), 7.85 (d, J )
8.4 Hz, 2H); 13C-NMR δ 27.59 , 28.94, 61.98, 121.95, 123.29,
124.13, 124.90, 127.90, 128.75, 130.37, 130.53, 130.87, 155.25;
MS m/z (%) 432 (46, M+), 247 (11), 217 (10), 215 (20), 186 (10),
185 (36), 184 (22), 183 (16), 169 (20), 155 (14); +FAB MS
(matrix: 3-nitrobenzyl alcohol) m/ z (%) 433 (19, M+ + 1), 432
(41, M+), 431 (6), 307 (10), 289 (10), 217 (14), 215 (44), 185
(61), 171 (26), 169 (30), 155 (43), 154 (100); HRMS M+
432.1231, calcd for C26H24S2O2 432.1216.
Ba se-Med ia ted Cou p lin g of 11 w ith 12. To a solution
of ethanolic KOH (481 mg in 170 mL 95% ethanol) was added
a solution of 11 (397 mg, 1.16 mmol) and 12 (290 mg, 1.16
mmol) in 70 mL of benzene, dropwise over (24 h) under Ar at
room temperature. The reaction was left stirring for an
additional 24 h after which the reaction solvent was evapo-
rated on a rotary evaporator. The residue was dissolved in

6482 J . Org. Chem., Vol. 62, No. 19, 1997
Ashram et al.
cisoid -syn -11,22-d im et h oxy-2,13-d it h ia [3.3](1,3)n a p h -
th a len op h a n e (6) was obtained as a colorless crystalline
powder (48 mg): mp 238-240 °C; 1H-NMR δ 3.56 (s, 6H), 3.60
(d, J ) 15.0 Hz, 2H), 3.83 (d, J ) 14.7 Hz, 2H), 4.54 (d, J )
15.0 Hz, 2H), 5.00 (d, J ) 14.7 Hz, 2H), 7.00-6.88 (m, 4H),
7.22 (d, J ) 8.1 Hz, 2H), 7.46 (s, 2H), 7.84 (d, J ) 7.8 Hz, 2H);
13C-NMR δ 27.43, 30.41, 62.44, 122.47, 123.95, 124.25, 124.34,
127.13, 130.29, 130.53, 130.67, 130.83, 155.09; MS m/ z (%)
432 (88, M+), 247 (44), 217 (28), 216 (58), 215 (100), 202 (10),
201 (32), 200 (18), 199 (5), 187 (13), 186 (52), 185 (10), 184
(87), 173 (10), 172 (18), 171 (35), 170 (15), 169 (35); HRMS
M+ 432.1185, calcd for C26H24S2O2 432.1216.
A fifth fraction, which was the most polar one, was also
isolated as an amorphous solid (42 mg) which decomposes at
138-140 °C. NMR spectral properties indicated this product
to be a mixture which could not be resolved by TLC. +FAB
MS revealed the presence of several pseudo-molecular ions,
suggestive of tetrameric species such as 2 and/or its isomers.
X-r a y Da ta for tr a n soid -a n ti-11,22-Dim eth oxy-2,13-
d ith ia [3.3](1,3)n a p h th a len op h a n e (3). Crystal (ex toluene)
data for 3: C26H24S2O2, triclinic, space group P1 (#2), a )
8.599(2) Å, b ) 9.192(2) Å, c ) 8.273(2)Å, R ) 108.68 (2)°, â )
112.54 (2)°, γ ) 103.00 (2)°, Z ) 1, Dcalc ) 1.368 g/cm3, crystal
size ) 0.400 × 0.350 × 0.250 mm. Intensity data were
measured at 299 K on a Rigaku AFC6S diffractometer with
Mo KR (λ ) 0.71069 Å) to 2θmax (deg) ) 50.1°; 1853 unique
reflections converged to a final R ) 0.034, for 1587 reflections
with I > 2.00σ(I); Rw ) 0.036, gof ) 2.62. Atomic coordinates
of the structure have been deposited with the Cambridge
Crystallographic Data Centre. These coordinates are avail-
able, upon request, from the Director, Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2 1EK,
U.K.
) 8.1 Hz, 2H); 13C-NMR δ 23.89, 33.30, 62.16, 122.72, 123.07,
124.38, 124.83, 127.35, 127.43, 130.26, 131.75, 133.61, 158.48;
MS m/ z (%) 368 (40, M+), 337 (22), 306 (100), 305 (18), 293
(4), 289 (4), 279 (4), 265 (4), 183 (14), 169 (8), 155 (11); HRMS
M+ 368.1735, calcd for C26H24O2 368.1776.
1,2,6,7-Tetr a h yd r o-3,4:8,9-d iben zop yr en e (7) fr om 3.
Irradiation of 3 under identical conditions as were used with
5 afforded a product whose spectral and physical properties
were identical with those of 7.
X-r a y Da ta for 1,2,6,7-tetr a h yd r o-3,4:8,9-d iben zop y-
r en e (7). Crystal data for 7: C24H18, triclinic, space group
P21 (#4), a ) 11.229(5) Å, b ) 15.31(1) Å, c ) 14.338(4)Å, â )
105.08 (3)°, Z ) 6, Dcalc ) 1.283 g/cm3, crystal size ) 0.400 ×
0.400 × 0.100 mm. Intensity data were measured at 299 K
on a Rigaku AFC6S diffractometer with Mo KR (λ ) 0.71069
Å) to 2θmax (deg) ) 50.1°; 4394 unique reflections converged
to a final R ) 0.046, for 2123 reflections with I > 2.00σ(I); Rw
) 0.030, gof ) 1.18. Atomic coordinates of the structure have
been deposited with the Cambridge Crystallographic Data
Centre. These coordinates are available, upon request, from
the Director, Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EK, U.K.
3,4:8,9-Diben zop yr en e (9) fr om 7. A solution of 7 (20 mg,
0.065 mmol) and DDQ (41 mg, 0.163 mmol) in 8 mL of benzene
was refluxed for 4 h. The solution was cooled to room
temperature and then filtered through a short Florisil column
and eluted with benzene. Evaporation of the solvent afforded
9 (12 mg, 61%) which was crystallized from benzene to give
pale orange crystals, mp 310-312 °C (308 °C).9
1,2,6,7-Tetr a h yd r o-3,4:9,10-d iben zop yr en e (8) fr om 4.
A solution of 4 (84 mg, 0.194 mmol) in 6 mL of trimethyl
phosphite was irradiated for 24 h at 254 nm as described for
5. After removal of the trimethyl phosphite by vacuum
distillation, the crude product was dried under vacuum and
then chromatographed by PLC using CH2Cl2:hexane (20:80)
to give 8 as a pale yellow solid (18 mg, 30%): mp 175-177 °C;
1H-NMR δ 3.10 (s, 4H), 3.4 (s, 4H), 7.50-741 (m, 4H), 7.59 (s,
2H), 7.80-7.74 (m, 2H), 8.13 and 8.01 (dd, 2H); 13C-NMR δ
23.27, 29.90, 121.67, 122.86, 123.56, 124.36, 125.32, 125.48,
125.82, 126.52, 127.91, 127.99, 129.26, 130.53, 131.03, 133.15,
134.69; MS m/ z (%) 306 (100, M+), 305 (37), 304 (18), 304 (18),
303 (20), 302 (24), 290 (11), 289 (15), 153 (25), 150 (24), 145
(23), 138 (15); HRMS M+ 306.1411, calcd for C24H18 306.1409.
3,4:9,10-Diben zop yr en e (10) fr om 8. A solution of 8 (22
mg, 0.072 mmol) and DDQ (41 mg, 0.163 mmol) in 8 mL of
benzene was refluxed for 4 h. The solution was cooled to room
temperature, filtered through a short Florisil column, and
eluted with benzene. Evaporation of the solvent afforded 10,
17 mg (85%) of which was crystallized from benzene to give
yellow leafy crystals, mp 281-282 °C (280 °C).9
2,6-Bis(br om om eth yl)-4-ter t-bu tyla n isole (20). To a
solution of 4.95 g (0.033 mol) of p-tert-butylanisole and 3.96 g
(0.132 mol) of paraformaldehyde in 25 mL of acetic acid was
added 25 mL of a solution of 15% hydrogen bromide in acetic
acid dropwise over 10 min, at room temperature under N2. The
reaction temperature was raised to 90-95 °C and after 2 days,
the reaction mixture was cooled to room temperature and then
diluted with 50 mL of CHCl3. The solution was washed several
times with water and then with saturated aqueous NaHCO3.
The organic layer was separated and dried over anhydrous
MgSO4 and filtered and the solvent evaporated. The oily
product was purified by column chromatography on SiO2 using
CHCl3:petroleum ether (20:80) to give 4.66 g (40%) of a
colorless solid: mp 95-96 °C; 1H-NMR δ 1.31 (s, 9H), 4.01 (s,
3H), 4.56 (s, 4H) and 7.36 (s, 2H); 13C-NMR δ 28.13, 31.25,
34.43, 62.11, 129.28, 131.0, 147.89, 154.27; MS m/ z (%) 348
(9, M+), 350 (18), 337 (6), 335 (12), 333 (6), 272 (14), 271 (100),
269 (99), 241 (16).
1,2,6,7-Tet r a h yd r o-3,4:8,9-d ib en zop yr en e (7) fr om 5.
(a ) Ir r a d ia tion for 24 h . A solution of 5 (141 mg, 0.326
mmol) in 10 mL of trimethyl phosphite under Ar in a quartz
tube was irradiated at 254 nm with stirring, for 24 h. The
triethyl phosphite was removed by vacuum distillation and the
yellow residue was dried under vacuum. Chromatography by
PLC using CH2Cl2:hexane 40:60 gave 7 (33 mg 33%) as yellow
1
crystals: mp 250-252 °C; H-NMR δ 3.18 and 3.21 (dd, 4H),
3.32 and 3.35 (dd, 4H), 7.50-7.42 (m, 4H), 7.62 (s, 2H), 7.81-
7.78 (m, 2H), 8.12-8.1 (m, 2H); 13C-NMR δ 23.82, 29.25,
123.48, 124.06, 125.33, 125.56, 127.98, 129.18, 130.87, 131.68,
133.14, 134.16; MS m/ z (%) 306 (100, M+), 305 (33), 303 (15),
302 (18), 289 (12), 153 (13), 151 (17), 145 (22); HRMS M+
306.1413, calcd for C24H18 306.1409. (b) Ir r a d ia tion for 7
h . When a solution of 5 (100 mg, 0.231 mmol) in 6.0 mL of
trimethyl phosphite under Ar in a quartz tube was irradiated
at 254 nm with stirring for 7 h and worked up as before,
chromatography by PLC using CH2Cl2:hexane (40:60) afforded
the following in order of increasing polarity: 7 (6 mg, 9%),
tr a n soid -a n ti-10,20-d im et h oxy-[2.2](1,3)n a p h t h a len o-
p h a n e (17a ) (13 mg, 15%) [as a colorless solid: mp >300 °C;
1H-NMR δ 2.67 (s, 6H), 2.75 (m, 2H), 2.82 (m, 2H), 2.97-3.00
(m, 2H), 3.56-3.60 (m, 2H), 7.38 (m, 2H), 7.45 (m, 2H), 7.69
(s, 2H), 7.81 (dd, J ) 8.1; 1.2 Hz, 2H); 8.10 (dd, J ) 8.1, 1.2
Hz, 2H); 13C-NMR δ 26.87, 31.40, 57.42, 117.55, 119.61, 120.63,
121.57, 124.74, 125.31, 129.62, 130.65, 131.44, 154.06; MS m/ z
(%) 368 (59, M+), 337 (23), 306 (100), 305 (20), 293 (3), 289
(4), 279 (4), 265 (4), 183 (13), 169 (7), 155 (12); HRMS M+
368.1703, calcd for C26H24O2 368.1776], tr a n soid -a n ti-11,21-
d im eth oxy-2-th ia -[3.2](1,3)n a p h th a len op h a n e (43) (6 mg,
1
6%) [as a colorless solid: mp 188-190 °C; H-NMR δ 2.64 (s,
3H), 2.94 (s, 3H), 3.05-2.83 (m, 3H), 3.60-3.48 (m, 2H), 3.63
(d, J ) 13.2 Hz, 1H), 3.76 (d, J ) 12.9 Hz, 1H), 4.22 (d, J )
13.2 Hz, 1H), 7.51-7.37 (m 4H), 7.72 (s, 1H), 7.78 (d, J ) 8.1
Hz, 1H), 7.83 (d, J ) 8.1 Hz, 1H), 7.94 (s, 1H), 8.05 (d, J ) 8.7
Hz, 1H), 8.17 (d, J ) 8.7 Hz, 1H); MS m/ z (%) 400 (94, M+),
216 (13), 215 (89), 201 (7), 200 (6), 198 (7), 197 (8), 185 (100),
183 (24), 170 (14), 168 (57); HRMS M+ 400.1493, calcd for
C26H24O2S, 400.1497], and tr a n soid -syn -10,20-d im eth oxy-
[2.2](1,3)n a p h th a len op h a n e (17b) (7 mg, 8%) [as a colorless
solid: mp 195-197 °C; 1H-NMR δ 2.74 (m, 2H), 3.46-3.36 (m,
4H), 3.65 (s, 6H), 3.94-3.84 (m, 2H), 5.91 (s, 2H), 6.88 (d, J )
8.1 Hz, 2H), 7.01- 6.97 (m, 2H), 7.27-7.22 (m, 2H), 7.63 (d, J
2,6-Bis(br om om eth yl)a n isole (21). To a solution of 1.17
g (8.57 mmol) of 2,6-dimethylanisole in refluxing CCl4 (100
mL) under N2, was added 3.66 g of N-bromosuccinimide (20.6
mmol) and 0.275 g of benzoyl peroxide15 in portions, over 1 h.
The reaction mixture was refluxed with stirring for an ad-
(15) Tashiro, M.; Yamato, T. J . Org. Chem. 1981, 46, 1543.

Synthesis of Dibenzopyrenes and Pyrenes
J . Org. Chem., Vol. 62, No. 19, 1997 6483
ditional 24 h. The solution was cooled to room temperature
and filtered. The filtrate was washed with aqueous saturated
NaHSO3. After drying and filtering, the solvent was evapo-
rated on a rotary evaporator and the residue was chromato-
graphed on SiO2 using CHCl3:petroleum ether (20:80) to give
21 as a colorless solid (0.98 g, 40%): mp 83-85 °C (lit.16 mp
a n t i -6-t er t -B u t y l-9,18-d im e t h o x y -2,11-d it h ia [3.3]-
m eta cyclop h a n e (27a ) was a colorless solid (0.075 g): mp
163-165 °C; 1H-NMR δ 1.37 (s, 9H), 3.20 (s, 3H), 3.27 (s, 3H),
3.39 (d, J ) 13.5 Hz, 2H), 3.42 (d, J ) 13.5 Hz, 2H), 3.77 (d,
J ) 13.5 Hz, 2H), 3.80 (d, J ) 13.5 Hz, 2H), 7.01 (t, J ) 7.5
Hz, 1H), 7.29 (d, J ) 7.5 Hz, 2H), 7.30 (s, 2H); 13C-NMR δ
26.34, 27.53, 29.66, 31.42, 34.27, 60.94, 123.72, 127.33, 127.87,
129.03, 130.45, 145.94, 156.6, 158.42; MS m/ e (%) 388 (59,
M+), 373 (4), 331 (3), 253 (13), 223 (13), 221 (25), 220 (11), 207
(13), 192 (13), 191 (43), 175 (74); HRMS M+ 388.1520, calcd
for C22H28S2O2 388.1529.
syn -6-t er t -B u t y l-9,18-d im e t h o x y -2,11-d it h ia [3.3]-
m eta cyclop h a n e (27b) was a colorless glassy oil which
solidified after refrigeration to give a colorless solid (0.35 g):
mp 107-108 °C; 1H-NMR δ 1.19 (s, 9H), 3.35 (d, J ) 14.7 Hz,
2H), 3.51 (s, 3H), 3.52 (s, 3H), 4.41 (d, J ) 14.7 Hz, 2H), 6.64
(t, J ) 7.5 Hz, 1H), 6.95 (d, J ) 7.5 Hz, 2H), 6.97 (s, 2H); 13C-
NMR δ 14.2, 30.11, 30.46, 31.23, 34.15, 62.19, 124.45, 126.45,
129.18, 129.50, 130.70, 145.56, 154.95, 156.97; MS m/ e (%)
388 (79, M+), 373 (5), 331 (4), 253 (16), 223 (17), 221 (29), 220
(16), 207 (15), 197 (13), 192 (19), 191(60), 177 (13), 176(13),
175 (83); HRMS M+ 388.1515, calcd for C22H28S2O2 388.1529.
a n ti- an d syn -9,18-Dim eth oxy-2,11-dith ia[3.3]m etacyclo-
p h a n e (28a a n d 28b). A solution of 21 (0.33 g) and 25 (0.23
g) in 60 mL of benzene was added to ethanolic KOH (0.73 g in
150 mL) over 8 h and the reaction was left stirring overnight.
PLC separation using CHCl3 gave two compounds in order of
increasing polarity: 28a and 28b.
1
75 °C); H-NMR δ 4.05 (s, 3H), 4.57 (s, 4H), 7.12 (q, 1H), and
7.38 (d, 2H); 13C-NMR δ 27.50, 62.25, 125.07, 131.94, 132.24
and 156.56; MS m/ e (%) 294 (12, M1+), 292 (6, M2+), 215 (81,
M1+ - Br), 213 (84, M2+ - Br), 185 (21) 183 (20), 119 (10), 106
(27), 105 (100), 104 (22), 103 (16), 79 (6), 77 (12), 65 (26), 63
(12), 51 (14), 39 (19).
1-Br om o-3,5-bis(br om om eth yl)ben zen e (23). The pro-
cedure described above for 21 was employed to prepare 23 from
1-bromo-3,5-dimethylbenzene (2.58 g, 13.90 mmol). The crude
product was chromatographed on SiO2 using CH2Cl2:petroleum
ether (10:90) and crystallized from hexane to give 23 (1.37 g,
29%); mp 97.5-99.0 °C (95-98 °C).17
1,3-Bis(m er ca p t om et h yl)-2-m et h oxy-5-ter t-b u t ylb en -
zen e (24). To a solution of 20 (1.25 g, 3.60 mmol) in 50 mL of
DMSO was added thiourea (0.66 g, 8.64 mmol), with stirring
under N2. After 5 h at room temperature the reaction was
quenched by pouring the mixture into a cold aqueous 10%
solution of NaOH (50 mL). The mixture was stirred at room
temperature for 2 h, after which it was cooled to 0 °C and
neutralized by addition of aqueous 3 M HCl. The ensuing
precipitate was filtered, washed with water, and air-dried. The
colorless solid obtained was purified by flash chromatography
on SiO2 using CHCl3:petroleum ether (70:30) to give 24 as a
colorless solid (0.820 g, 89%): mp 80-81 °C (lit.17 mp 81-82
a n ti-9,18-Dim et h oxy-2,11-d it h ia [3.3]m et a cyclop h a n e
1
(28a ) was a colorless solid (36 mg, 10%): mp 248-25 °C; H-
1
°C); H-NMR δ 1.31 (s, 9H), 1.90 (t, J ) 7.5 Hz, 2H), 3.77 (d,
NMR δ 3.26 (s, 6H), 3.43 (d, J ) 13.5 Hz, 4H), 3.80 (d, J )
13.5 Hz, 4H), 7.04 (t, J ) 7.5 Hz, 2H), 7.30 (d,J ) 7.5 Hz, 4H);
13C-NMR δ 26.93, 61.18, 123.82, 128.83, 130.69 and 158.67;
MS m/ e (%) 332 (43, M+), 197 (19), 167 (16), 165 (25), 151
(15), 136 (12), 135 (40), 134 (27), 121 (29), 119 (27) 105 (44);
HRMS M+ 332.0903, calcd for C18H20S2O2 332.0905.
J ) 7.5 Hz, 4H), 3.88 (s, 3H) and 7.23 (s, 2H). 13C-NMR
(CDCl3) δ 23.51, 31.38, 34.45, 62.22, 126.20, 133.80, 147.62,
153.10; MS m/ e (%) 258 (7), 257 (12), 256 (72, M+), 243 (5),
242 (7), 241 (47), 223 (48), 178 (13), 177 (100), 165 (17), 161
(11).
syn -9,18-Dim et h oxy-2,11-d it h ia [3.3]m et a cyclop h a n e
(28b) was a colorless solid (136 mg, 36%): mp 220-223 °C;
1H-NMR δ 3.37 (d, J ) 14.7 Hz, 4H), 3.52 (s, 6H), 4.42 (d, J )
14.7 Hz, 4H), 6.64 (t, J ) 7.8 Hz, 2H), 6.97 (d, J ) 7.8 Hz,
4H); 13C-NMR δ 30.16, 62.18, 124.23, 129.56, 130.55, 156.98;
MS m/ e (%), 332 (100, M+), 298 (3), 198 (5), 197 (48), 167 (35),
166 (16), 165 (47), 164 (28), 151 (20), 136 (32), 135 (79), 134
(52), 133 (56), 121 (42), 119 (36); HRMS M+ 332.0896, calcd
for C18H20S2O2 332.0905.
6-t er t -B u t y l-9-m e t h ox y-2,11-d it h ia [3.3]m e t a c y c lo -
p h a n e (29). A solution of 22 (0.63 g, 2.47 mmol) and 24 (0.65
g, 2.47 mmol) in 50 mL of benzene was added to ethanolic KOH
(300 mL) over 6 h. The reaction mixture was stirred for an
additional 2 h before workup. The crude product was flash
chromatographed on SiO2 using CHCl3:petroleum ether (80:
20) to give 29 as a colorless solid (0.655 g), which could be
crystallized from hexane:benzene (10:1) to give needles (0.45
g): mp 177-178 °C (lit.18 mp 182.5-183 °C); 13C-NMR δ 31.10,
31.31, 34.10, 37.88, 62.10, 126.39, 126.61, 128.55, 129.25,
130.10, 137.79, 146.39, 154.10.
15-B r o m o -6-t er t -b u t y l-9-m e t h o x y -2,11-d it h ia [3.3]-
m eta cyclop h a n e (30). A solution of 23 (1.44 g, 4.26 mmol)
and 24 (1.09 g, 4.26 mmol) in 230 mL of benzene was added
dropwise to the ethanolic KOH solution (570 mL) over 16 h.
The crude product was chromatographed on SiO2 using CHCl3:
petroleum ether (80:20) to give 30 as a colorless solid (0.61 g,
58%) which was crystallized from hexane/benzene (1:1): mp
212-214 °C (lit.18 mp 218-219 °C).
2,7-Di-ter t-bu tyl-4,5,9,10-tetr a h yd r op yr en e (33). Typ i-
ca l P r oced u r e. A solution of 26 (97 mg, 0.22 mmol) in 4.5
mL of triethyl phosphite in a quartz tube was irradiated at
254 nm with stirring and under Ar for 18 h. The triethyl
phosphite was removed by vacuum distillation, and the crude
product was dried under vacuum and then chromatographed
by PLC using CHCl3:petroleum ether (1:9) to give 33 as a
colorless solid (39 mg, 56%): mp 232-233 °C (lit.19 mp 234-
235 °C); 1H-NMR δ 1.34 (s, 18H), 2.87 (s, 8H), 7.07 (s, 4H);
2,6-Bis(m er ca p tom eth yl)a n isole (25). The procedure
described above for 24 was employed to prepare 25 from 21.
Flash chromatography on SiO2 using CHCl3:petroleum ether
(60:40) gave 25 as a colorless solid (0.24 g, 65%): mp 28-29
1
°C; H-NMR δ 1.89 (t, J ) 7.8 Hz, 2H), 3.78 (d, J ) 7.8 Hz,
4H), 3.90 (s, 3H), 7.23-7.05 (m, 3H); 13C-NMR δ 23.18, 62.32,
124.91, 129.22, 134.76, 155.36.
P r ep a r a tion of d ith ia [3.3]m eta cyclop h a n es: 6,15-d i-
t er t -b u t yl-9,18-d im e t h oxy-2,11-d it h ia [3.3]m e t a cyclo-
p h a n e (26). Typ ica l p r oced u r e. A solution of 24 (0.54 g,
2.11 mmol) and 20 (0.72 g, 2.1 mmol) in 55 mL of benzene
was added dropwise over 10 h with stirring to a solution of
0.35 g of KOH in 250 mL of ethanol, under N2. After the
addition was complete the reaction was stirred for an ad-
ditional 6 h. The mixture was then concentrated on a rotary
evaporator and the residue dissolved in 50 mL of CHCl3. The
organic layer was washed with two 25-mL portions of aqueous
10% HCl, dried over MgSO4 and filtered. The solvent was
evaporated on a rotary evaporator and the residue was flash
chromotographed on SiO2 using CHCl3:petroleum ether (80:
20) to give 26 as a colorless solid (0.38 g, 38%): mp 253-255
°C (lit.15 mp 257-258 °C); 1H-NMR δ 1.36 (s, 18H), 3.21 (s,
6H), 3.39 (d, J ) 13.5 Hz, 4H), 3.79 (d, J ) 13.5 Hz, 4H), 7.29
(s, 4H); 13C-NMR δ 26.96, 31.42, 34.31, 60.70, 127.59, 127.73,
145.85, 156.35; MS m/ e (%) 444 (61, M+), 4.29 (4), 387 (3),
267 (3), 253 (33), 223 (29), 222 (12), 221 (38), 220 (13), 192
(33), 191 (71), 189 (16), 177 (18), 176 (13), 175 (87), 165 (18).
Compounds 27-29 were obtained in the same manner as
described above.
a n ti- a n d syn -6-ter t-Bu tyl-9,18-d im eth oxy-2,11-d ith ia -
[3.3]m eta cyclop h a n e (27a a n d 27b). A solution of 21
(0.69g) and 24 (0.60 g) in 50 mL of benzene was added to
ethanolic KOH (0.32 g in 250 mL) over 16 h. Chromatographic
separation on SiO2 using CHCl3:petroleum ether (70:30) gave
two compounds in order of increasing polarity: 27a and 27b.
(16) Vogtle, F.; Neumann, P. Tetrahedron 1970, 26, 5299.
(17) Sherrod, S. A.; da Costa, R. L.; Barnes, R. A.; Boekelheide, V.
J . Am. Chem. Soc. 1974, 96, 1565.
(18) Tashiro, M.; Yamato, T. Org. Prep. Proced. Int. 1981, 13, 1.

6484 J . Org. Chem., Vol. 62, No. 19, 1997
Ashram et al.
13C-NMR δ 28.73, 31.46, 34.54, 122.78, 128.12, 134.55, 149.60;
MS m/ e (%) 318 (79, M+), 304 (26), 303 (100), 273 (8), 205 (8),
203 (8), 202 (7), 144 (28).
2-ter t-Bu tyl-4,5,9,10-tetr a h yd r op yr en e (34). A solution
of 27 (0.16 g, 0.44 mmol) in 4.5 mL of triethyl phosphite was
photolyzed as above for 18 h. After workup, the crude product
was chromatographed by PLC using CHCl3:petroleum ether
(20:80) to give 34 as a colorless solid (26 mg, 22%): mp 94-95
°C (lit.19 mp 108-109.5 °C); 13C-NMR (CDCl3) δ 28.43, 28.61,
31.43, 34.58, 122.91, 122.75, 125.77, 126.62, 128.1, 130.62,
134.90, 135.05, 150.11.
rated on a rotary evaporator. The residue was dissolved in
50 mL of CH2Cl2 and the organic solution was washed with
two 25-mL portions of aqueous 10% HCl. The organic layers
were combined, dried over anhydrous MgSO4, and filtered, and
the solvent was evaporated on a rotary evaporator. The crude
product was flash chromatographed on SiO2 using CH2Cl2:
petroleum ether (40:60) to give 0.711 g (1.65 mmol, 91%) of a
mixture of isomers 37 and 38. A small amount of 5,16-
dimethoxy-2,13-dithia[3.3](1,3)naphthalenophane (37) was ob-
tained in a pure enough state from repeated PLC separation
using CH2Cl2:petroleum ether (40:60) to be characterized: mp
191-193 °C; 1H-NMR δ 3.82 (s, 6H), 4.02 (s, 4H), 4.18 (s, 4H),
7.21 (s, 2H), 7.24-7.29 (m, 4H), 7.78-7.81 (m, 2H), 7.97-8.00
(m, 2H); 13C-NMR δ 31.59, 35.92, 62.19, 122.14, 124.32, 124.46,
125.22, 125.42, 127.71, 130.98, 131.21, 152.75; MS m/ e (%)
433 (16, M+ + 1), 432 (48, M+), 247 (11), 216 (11), 215 (35),
201 (10), 186 (17), 185 (100), 183 (14), 172 (7), 171 (23), 170
(25), 154 (11), 153 (13), 141 (25), 139 (11), 129 (11), 128 (11).
The mixture consisting of 37 and 38 could not be further
separated using either flash chromatography or PLC and was
used as a mixture directly in the subsequent photolytic step.
tr a n soid -a n ti-4,14-Dim et h oxy[2.2](1,3)n a p h t h a len o-
ph a n e (41) a n d cisoid-a n ti-4,18-Dim eth oxy[2.2](1,3)n a p h -
th a len op h a n e (42). A solution of the mixture of 37 and 38
(150 mg, 0.35 mmol), obtained as described above, in 3.5 mL
of trimethyl phosphite in a quartz tube was irradiated at 254
nm with stirring and under Ar for 24 h. The trimethyl
phosphite was removed by vacuum distillation and the yellow
residue was dried under vacuum and then chromatographed
by PLC with CH2Cl2:hexane (45:55) to give two fractions, in
order of increasing polarity: 41 and 42.
Alternatively, 34 (25 mg, 34%) was also obtained from the
photolysis of 29 (110 mg, 0.284 mmol) in 4.0 mL of triethyl
phosphite.
4,5,9,10-Tetr a h yd r op yr en e (35). A solution of 28 (0.15
g, 0.35 mmol) in 4.5 mL of triethyl phosphite was photolyzed
as above for 18 h. After workup, the crude product was
purified by PLC using CHCl3:petroleum ether (20:80) to give
35 as a colorless solid (15 mg, 33%): mp 132-134 °C (lit.19
1
mp 136-138 °C); H-NMR δ 2.88 (s, 8H) and 7.51-7.05 (m,
6H); 13C-NMR δ 28.33, 125.90, 127.02, 130.59 and 135.38; MS
m/ e (%) 206 (100, M+).
P h otolysis of 30. A solution of 30 (0.150 g, 0.35 mmol) in
5.0 mL of triethyl phosphite was photolyzed as above for 6 h.
After workup, the crude product was chromatographed by PLC
using CHCl3:petroleum ether (20:80) to give three fractions
in increasing order of polarity which consisted of 2, 6, and 20
mg. None of the spectral characteristics of these products were
consistent with those anticipated for 2-bromo-7-tert-butyl-
4,5,9,10-tetrahydropyrene. These products could not be fur-
ther characterized.
tr a n soid -a n ti-4,14-Dim et h oxy[2.2]-(1,3)n a p h t h a len o-
p h a n e (41) was obtained as a colorless solid (21 mg, 15%):
Oxid a tion of 33 w ith DDQ. Typ ica l P r oced u r e.
A
solution of 33 (65 mg, 0.204 mmol) and 116 mg of DDQ in 25
mL of benzene was refluxed for 8 h. After cooling, the reaction
mixture was filtered through a short column of Florisil and
washed with benzene. The solvent was evaporated to dryness
on a rotary evaporator to give 62 mg (97%) of 2,7-di-tert-
butylpyrene, which after crystallization from hexane afforded
pale yellow crystals: mp 204-206 °C (lit.19 mp 210-212 °C).
In a similar manner, 2-tert-butylpyrene19 and pyrene were
obtained from 34 and 35, respectively.
1
mp 230-233 °C; H-NMR δ 2.00 (m, 2H), 2.24 (m, 2H), 3.72
(m, 2H), 3.95 (m, 2H), 4.10 (s, 6H), 4.51 (s, 2H), 7.52-7.55 (m,
4H), 8.13-8.16 (m, 4H), 8.21-8.24 (m, 2H); 13C-NMR δ 33.14,
35.23, 62.99, 122.98, 123.65, 125.22, 125.35, 128.67, 129.45,
131.87, 136.26, 152.49; MS m/ e (%) 369 (21, M+ + 1), 368 (53,
M+), 367 (26), 354 (16), 353 (12), 352 (55), 339 (16), 336 (28),
335 (18), 321 (12), 307 (7), 184 (20), 183 (100), 169 (17), 155
(28), 141 (58), 115 (57), 28 (37); HRMS M+ 368.1777, calcd for
C26H24O2 368.1775.
2,4-Bis(m er ca p tom eth yl)-1-m eth oxyn a p h th a len e (40).
To a solution of 0.85 g (2.5 mmol) of 2,4-bis(bromomethyl)-1-
methoxynaphthalene (39)2 in 50 mL of DMSO was added 0.473
g (0.21 mmol) of thiourea, with stirring, under N2. After 6 h
at room temperature the reaction was quenched by pouring
the mixture into a cold aqueous 10% solution of NaOH (50
mL). The mixture was stirred at room temperature for 2 h,
after which it was cooled to 0 °C and acidified by addition of
aqueous 4 M HCl. The reaction mixture was extracted twice
with 30-mL portions of CH2Cl2. The organic layers were
combined and washed with two 20-mL portions of water. The
organic layers were combined and dried over anhydrous
MgSO4 and filtered, and the solvent was evaporated on a
rotary evaporator. The crude product was flash chromato-
graphed on SiO2 using CH2Cl2:petroleum ether (40:60) to give
0.45 g (1.8 mmol, 73%) of 40 as an oil: 1H-NMR δ 1.89 (t, J )
6.9 Hz, 1H), 1.92 (t, J ) 7.5 Hz, 1H), 3.92 (d, J ) 7.5 Hz, 2H),
3.99 (s, 3H), 4.15 (d, J ) 6.9 Hz, 2H), 7.42 (s, 1H), 7.52-7.58
(m, 2H), 8.02-8.05 (m, 1H), 8.11-8.14 (m, 1H); 13C-NMR δ
23.00, 26.35, 62.70, 123.08, 124.09, 126.20, 126.44, 127.67,
128.55, 128.98, 131.36, 133.48, 152.77; MS m/ e (%) 251 (5,
M+ + 1), 250 (35, M+), 218 (15), 217 (100), 184 (10), 183 (32),
171 (10), 154 (10), 141 (18), 115 (15), 28 (33); HRMS M+
250.0486, calcd for C13H14S2O 250.0485.
ci soi d -a n t i -4,18-D im e t h o x y [2.2](1,3)n a p h t h a le n o -
p h a n e (42) was obtained as a colorless solid which was further
purified by PLC using ethyl acetate: petroleum ether (1:9) to
1
give 28 mg (22%) of 42: mp 189-191 °C; H-NMR δ 2.01 (d,
J ) 10 Hz, 2H), 2.16 (d, J ) 9 Hz, 2H), 3.72 (d, J ) 9 Hz, 2H),
3.97 (d, J ) 10 Hz, 2H), 4.08 (s, 6H), 4.45 (s, 2H), 7.52-7.55
(m, 4H), 8.16-8.23 (m, 2H); 13C-NMR δ 33.64, 34.66, 62.98,
122.99, 123.53, 125.29, 125.39, 127.39, 128.72, 130.68, 132.04,
136.16, 152.25 MS m/ e (%) 368 (86, M+), 353 (56), 340 (17),
339 (17), 338 (24), 337 (17), 337 (63), 322 (8), 321 (9), 306 (12),
184 (44), 183 (99), 169 (26), 155 (22), 154 (52), 153 (34), 152
(34), 144 (10), 141 (62); HRMS M+ 368.1765, calcd for C26H24O2
368.1775.
Ack n ow led gm en t. We are grateful to Mu’Tah Uni-
versity, J ordan, for providing a scholarship to one of us
(M.A.) and to The Natural Sciences and Engineering
Research Council of Canada (NSERC) and Memorial
University for financial support. We thank Dr. C. R.
J ablonski for the high-resolution NMR spectra and Ms.
M. Baggs for the mass spectra. All FAB/MS and some
HRMS were obtained by Mr. D. Drummond, Depart-
ment of Chemistry, University of New Brunswick.
Ba se-Med ia ted Cou p lin g of 39 w ith 40. To a solution
of ethanolic KOH (398 mg in 250 mL 95% ethanol) was added
a solution of 39 (610 mg, 1.78 mmol) and 40 (445 mg, 1.78
mmol) in 110 mL of benzene dropwise over 12 h under Ar at
room temperature. The reaction was left stirring for an
additional 24 h, after which the reaction solvent was evapo-
1
Su p p or tin g In for m a tion Ava ila ble: High-resolution H,
13C NMR spectra and mass spectra of all the new compounds
reported in this paper (61 pages). This material is contained
in libraries on microfiche, immediately follows the article in
the microfilm version of the journal, and can be ordered from
the ACS; see any current masthead page for the ordering
information.
(19) Tashiro, M.; Yamato, T.; Kobayashi, K.; Arimura, T. J . Org.
Chem. 1987, 52, 3196.
J O970181W