Cyclohexylene-Bridged Porphyrin Quinones with Variable Acceptor Strength as Biomimetic Models for Photosynthesis: Evidence for Twist-Boat Conformation

Article abstract of DOI:10.1021/jo970752k

Rigidly and covalently linked porphyrin quinones are well-suited as biomimetic model compounds for studying the photoinduced electron transfer (PET) reaction occurring in primary processes of photosynthesis. In this context, the synthesis of new porphyrin quinones with a cis- or trans-1,4-disubstituted cyclohexylene bridge linking the electron donor and the electron acceptor is reported. To study the dependence of the PET rate of the difference of the free enthalpy of the PET reaction, four quinones with different structures and therefore redox potentials were used as electron acceptor components. As a whole, two series of each four new cis- and trans-1,4-cyclohexylene-bridged porphyrin quinones with variable acceptor strength were synthesized. The most important synthetic steps comprised the free radical addition of the ester functionalized cyclohexylene bridge to the quinone, reduction of the ester to the alcohol group with lithium borohydride or DIBALH, oxidation of the alcohol to the corresponding aldehyde with PCC or TEMPO (2,2,6,6-tetramethylpiperidine1-oxyl)/NaOCl, and condensation of these aldehydes with pyrrole and 4-methylbenzaldehyde under equilibrium conditions. Analysis of the ¹H NMR spectra unambiguously indicated the chair conformation for the cyclohexane ring of all porphyrin precursors and Zrarcs-cyclohexane-bridged porphyrin quinones, whereas the cis-cyclohexane-bridged porphyrin quinones had the cyclohexane ring in the unusual twist-boat conformation. This was additionally confirmed by an X-ray crystal structure of one of the cis-porphyrin quinones and the corresponding trans-porphyrin quinone. NOE experiments gave information about the spatial arrangement of the diastereomeric target compounds in solution.

Full text of DOI:10.1021/jo970752k

8666
J . Org. Chem. 1997, 62, 8666-8680
Cycloh exylen e-Br id ged P or p h yr in Qu in on es w ith Va r ia ble
Accep tor Str en gth a s Biom im etic Mod els for P h otosyn th esis:
Evid en ce for Tw ist-Boa t Con for m a tion
Henrik Dieks, Mathias O. Senge, Burkhard Kirste, and Harry Kurreck*
Institut fu¨r Organische Chemie (WE 02), Freie Universita¨t Berlin, Takustrasse 3,
D-14195 Berlin, Germany
Received April 28, 1997X
Rigidly and covalently linked porphyrin quinones are well-suited as biomimetic model compounds
for studying the photoinduced electron transfer (PET) reaction occurring in primary processes of
photosynthesis. In this context, the synthesis of new porphyrin quinones with a cis- or trans-1,4-
disubstituted cyclohexylene bridge linking the electron donor and the electron acceptor is reported.
To study the dependence of the PET rate of the difference of the free enthalpy of the PET reaction,
four quinones with different structures and therefore redox potentials were used as electron acceptor
components. As a whole, two series of each four new cis- and trans-1,4-cyclohexylene-bridged
porphyrin quinones with variable acceptor strength were synthesized. The most important synthetic
steps comprised the free radical addition of the ester functionalized cyclohexylene bridge to the
quinone, reduction of the ester to the alcohol group with lithium borohydride or DIBALH, oxidation
of the alcohol to the corresponding aldehyde with PCC or TEMPO (2,2,6,6-tetramethylpiperidine-
1-oxyl)/NaOCl, and condensation of these aldehydes with pyrrole and 4-methylbenzaldehyde under
equilibrium conditions. Analysis of the 1H NMR spectra unambiguously indicated the chair
conformation for the cyclohexane ring of all porphyrin precursors and trans-cyclohexane-bridged
porphyrin quinones, whereas the cis-cyclohexane-bridged porphyrin quinones had the cyclohexane
ring in the unusual twist-boat conformation. This was additionally confirmed by an X-ray crystal
structure of one of the cis-porphyrin quinones and the corresponding trans-porphyrin quinone. NOE
experiments gave information about the spatial arrangement of the diastereomeric target compounds
in solution.
In tr od u ction
The aliphatic cyclohexylene spacer, linking porphyrin
and quinone either in 1,4-cis or -trans conformation,
respectively, has proved useful in this context.2-4 In the
present paper we take advantage of this system and
report on synthesis and characterization of a variety of
P-Q’s which have in common the donor 10,15,20-tris(4-
methylphenylene)porphyrin-5-yl residue, abbreviated as
P and the cyclohexylene spacer, whereas the quinone
acceptors (Q) are different (Figure 1). The underlying
idea was to essentially keep the basic molecular frame
constant and to modify only one parameter (the driving
force ∆G° of PET). According to Marcus theory this free
energy of reaction significantly influences the PET rate
constants.5 The Marcus theory predicts at first an
increase in the PET rate constant with increasing exer-
gonicity in the “normal region” of the PET reaction, i.e.,
with more negative values for ∆G°. Subsequently, the
PET rate passes through a maximum value and finally
will decrease with further increasing exergonicity in the
“inverted region”.
Photosynthetic reaction centers (RC) consist of the
protein matrix and the donor-acceptor redox active
pigments. In RC photoinduced electron transfer (PET)
takes place within about 3 ps after singlet state excitation
and the initial energy conversion act proceeds with a
quantum yield of nearly unity. The unpaired electron
moves energetically downhill from (bacterio)chlorophylls
or their corresponding dimers to (bacterio)pheophytins
and quinone acceptors QA and QB.
To gain a better insight into the dependencies of PET
rate constants on donor-acceptor distance, relative
orientation, free energy of reaction, and electronic cou-
pling, numerous porphyrin quinone (P-Q) models have
been prepared and studied by different optical and
magnetic resonance spectroscopic techniques. Recent
reviews report on synthesis and investigations of co-
valently linked donors and acceptors extending even to
so-called pentads connecting five different PET active
moieties.1 One of the requirements to define a “good”
model compound is a fairly rigid structure of the ag-
gregate, since flexible spacers result in some uncertainty
in the geometrical relationship between donor and ac-
ceptor. Well-defined geometrical parameters are a pre-
requisite for a sound theoretical interpretation of the
spectroscopic data.
Hence, the goal was to obtain a series of compounds
with gradually increasing exergonicity. Therefore, the
(2) von Gersdorff, J .; Huber, M.; Schubert, H.; Niethammer, D.;
Kirste, B.; Plato, M.; Mo¨bius, K.; Kurreck, H.; Eichberger, R.; Kietz-
mann, R.; Willig, F. Angew. Chem. 1990, 102, 690-692; Angew. Chem.,
Int. Ed. Engl. 1990, 29, 670-672. Lendzian, F.; Schlu¨pmann, J .; von
Gersdorff, J .; Mo¨bius, K.; Kurreck, H. Angew. Chem. 1991, 103, 1536-
1539; Angew. Chem., Int. Ed. Engl. 1991, 30, 1461-1463. von Gers-
dorff, J .; Kirste, B.; Kurreck, H. Liebigs. Ann. Chem. 1993, 897-903.
Schlu¨pmann, J .; Salikhov, K. M.; Plato, M.; J aegermann, P.; Lendzian,
F.; Mo¨bius, K. Appl. Magn. Reson. 1991, 2, 117-142.
X Abstract published in Advance ACS Abstracts, November 1, 1997.
(1) Wasielewski, M. R. Chem. Rev. (Washington, D.C.) 1992, 92,
435-461. Gust, D.; Moore, T. A. Adv. Photochem. 1991, 16, 1-65. Gust,
D.; Moore, T. A. Top. Curr. Chem. 1991, 159, 103-151. Bixon, M.;
Fajer, J .; Feher, G.; Freed, J . H.; Gamliel, D. A.; Hoff, A. J .; Levanon,
H.; Mo¨bius, K.; Nechushtai, R.; Norris, J . R.; Scherz, A.; Sessler, J . L.;
Stehlik, D. Isr. J . Chem. 1992, 32, 469-518. Kurreck, H.; Huber, M.
Angew. Chem. 1995, 107, 929-947; Angew. Chem., Int. Ed. Engl. 1995,
34, 849-866.
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1995, 51, 3535-3548.
(4) Szelinski, H.; Niethammer, D.; Tian, P.; Kurreck, H. Tetrahedron
1996, 52, 8497-8516.
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S0022-3263(97)00752-4 CCC: $14.00 © 1997 American Chemical Society

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8667
Starting from 3-(trifluoromethyl)phenol (5), 3-(trifluo-
romethyl)-1,4-benzoquinone (9) was obtained following
a literature procedure,9 which, however, was simplified
and improved. The bromination of 9, which generally
proceeds rapidly with 1,4-benzoquinones,10 yielded the
dibromo adduct 10. The acid-induced 2-fold tautomer-
ization11 of such quinone dibromides yielded the hydro-
quinone 11, which after oxidation with DDQ gave 2,3-
dibromo-5-(trifluoromethyl)-1,4-benzoquinone (4) in 79%
yield.
Syn th eses of th e P or p h yr in Qu in on es. The reac-
tion pathways for the different porphyrin quinones are
shown in Schemes 2-4. The free radical alkylation of
the quinones in order to link the cyclohexylene bridge to
the quinone (Scheme 2) followed a procedure originally
described by J acobsen et al.12 A cis/trans mixture of
12a /b and the quinones 1-4 were reacted at 40 °C in a
two-phase system of dichloromethane/water with am-
monium peroxodisulfate as oxidant and silver nitrate as
catalyst. The products 13a /b-16a /b were obtained in
30-50% yield with a cis/trans ratio of 3:2. Due to poor
separability of the alkylated quinones with HPLC on a
preparative scale, only small amounts were separated for
analytical purposes.
F igu r e 1. Target molecules with the same electron donor
(10,15,20-tris(4-methylphenylene)porphyrin-5-yl residue, ab-
breviated as P) for all compounds, a cis- or trans-cyclohexylene
spacer, and different quinones (Q) as electron acceptors.
In the next step the alkylated quinones 13a /b-16a /b
were reduced with sodium hyposulfite13 or by catalytic
hydrogenation13 to the corresponding hydroquinones 17a /
b-20a /b without isolation. The subsequent reduction of
the methyl ester group to the alcohol group was per-
formed with lithium borohydride14 or DIBALH15 (Scheme
2). Only the diastereomeric acceptor-substituted hydro-
quinones 24a /b are stable and could be isolated (total
yield 93%) and separated by HPLC. An attempted
isolation of the other hydroquinones 21a /b-23b led to
their decomposition. Hence, 21a /b-23a /b were im-
mediately oxidized with iron(III) chloride or ammonium
cerium(IV) nitrate to the corresponding quinones 25a /
b-27a /b in 57-75% overall yield. With the exception
of 27a /b , all product mixtures of the diastereomeric
alcohols could be separated by HPLC. The method of
choice for the conversion of the alcohols to the corre-
sponding aldehydes (Scheme 3) in the case of 25a , 25b,
26a and 26b proved to be the oxidation with TEMPO as
catalyst and sodium hypochlorite as oxidizing agent.16
The products were obtained in high yield (85-90%) and
are isomerically pure. Unfortunately, this method failed
in the case of 24a , 24b, and 27a /b due to rapid decom-
position of the educts. These aldehydes could be obtained
only with PCC17 (pyridinium chlorochromate) as oxidant
in ca. 75% yield. Due to the acidic character of PCC,17
isomerization reactions of the productssmost probable
via a keto-enol tautomerizationswere observed result-
quinones 1-4 were chosen as acceptors. They span
different redox potentials ranging from -0.70 V (1) to
+0.08 V (4) (measured vs SCE in dichloromethane with
ferrocene as standard) which results in different driving
forces ∆G°.6 Due to the electron-withdrawing substitu-
ents of 4, this quinone is the strongest oxidizing agent
of all electron acceptors used in our model compounds.
Thus, the most exergonic PET reaction is to be expected
which should give rise to observe a PET reaction in the
“Marcus inverted region”.
To introduce some rigidity and to retain similar geo-
metrical arrangements between quinone and bridge, the
quinones bear a methyl or trifluoromethyl group, respec-
tively, next to the linking position. Detailed structural
information could be obtained by X-ray crystallography
of two diastereomeric target P-Q’s. Only the synthesis
of the ubiquinone derivatives has already been outlined
previously in a short communication.7 Optical and
electron paramagnetic resonance spectroscopic studies on
some of these systems have already been8 or will be
published elsewhere.
Resu lts a n d Discu ssion
Syn th esis of 2,3-d ibr om o-5-(tr iflu or om eth yl)-1,4-
ben zoqu in on e. Whereas syntheses for three of the four
electron acceptors, i.e., for the quinones 1,31 2,27 and 3,28
have already been described in the literature, the syn-
thetic pathway for the preparation of the hitherto un-
known quinone 4 is depicted in Scheme 1.
(9) Littell, R.; Allen, G. R., J r. J . Org. Chem. 1968, 33, 2064-2069.
(10) Atkinson, R. C.; de la Mare, P. B. D.; Larsen, D. S. J . Chem.
Soc., Perkin Trans. 2 1983, 271-279.
(11) Savoie, J . Y.; Brassard, P. Can. J . Chem. 1966, 44, 2867-2872.
(12) J acobsen, N.; Torssell, K. Liebigs Ann. Chem. 1972, 763, 135-
147. J acobsen, N.; Torssell, K. Acta Chem. Scand. 1973, 27, 3211-
3216. Goldman J .; J acobsen, N.; Torssell, K. Acta Chem. Scand. 1974,
B28, 492-500.
(6) Rehm, D.; Weller, A. Ber. Bunsen-Ges. 1969, 73, 834-839. Rehm,
D.; Weller, A. Isr. J . Chem. 1970, 8, 259-271. Kavarnos, G. J . Top.
Curr. Chem. 1990, 156, 21-58.
(7) Dieks, H.; Sobek, J .; Tian, P.; Kurreck, H. Tetrahedron Lett. 1992,
33, 5951-5954.
(13) Ulrich, H.; Richter, R. In Houben-Weyl, Methoden der orga-
nischen Chemie; Vol. VII/3a; Grundmann, E., Ed.; G. Thieme: Stut-
tgart, 1977; p 648.
(8) Fuchs, M.; von Gersdorff, J .; Dieks, H.; Kurreck, H.; Mo¨bius, K.;
Prisner, T.; J . Chem. Soc., Faraday Trans. 1996, 92, 949-955. Kurreck,
H.; Aguirre, S.; Batchelor, S. N.; Dieks, H.; von Gersdorff, J .; Kay C.
W. M., Mo¨ssler, H.; Newman, H.; Niethammer, D.; Schlu¨pmann, J .;
Sobek, J .; Speck, M.; Stabingis, T.; Sun, L.; Tian, P.; Wiehe A.; Mo¨bius
K. Sol. En. Mater. Sol. Cells 1995, 38, 91-110. Kurreck, H.; Aguirre
S.; Dieks, H.; Ga¨tschmann, J .; von Gersdorff, J .; Newman H.; Schubert,
H.; Speck, M.; Stabingis, T.; Sobek, J .; Tian, P. Radiat. Phys. Chem.
1995, 45, 853-865. Kurreck, H.; Tian, P.; Dieks, H.; von Gersdorff, J .;
Newman, H.; Schubert, H.; Stabingis, T.; Wiehe A.; Sobek, J . Appl.
Magn. Reson. 1994, 6, 17-27.
(14) Brown, H. C.; Choi, Y. M.; Narasimhan, S. J . Org. Chem. 1982,
47, 1604-1606. Brown, H. C.; Narasimhan, S.; Choi, Y. M. J . Org.
Chem. 1982, 47, 4702-4708.
(15) Winterfeldt, E. Synthesis 1975, 617-630.
(16) Anelli, P. L.; Biffi, C.; Montanari, F.; Quici, S. J . Org. Chem.
1987, 52, 2559-2562. Anelli, P. L.; Montanari, F.; Quici, S. Org. Synth.
1990, 69, 212-219.
(17) Corey, E. J .; Suggs, J . W. Tetrahedron Lett. 1975, 31, 2647-
2650.

8668 J . Org. Chem., Vol. 62, No. 25, 1997
Sch em e 1. Syn th esis of 2,3-Dibr om o-5-(tr iflu or om eth yl)-1,4-ben zoqu in on e (4)
Dieks et al.
Sch em e 2. F r ee Ra d ica l Alk yla tion of th e Qu in on es a n d Red u ction of th e Ester s to th e Alcoh ol Gr ou p s
ing in cis/trans mixtures of the products 28a (cis/trans
ratio 9:1) and 28b (cis/trans ratio 5:95) despite starting
with the isomerically pure educts 24a and 24b, respec-
tively. Likewise, oxidation of 27a /b resulted in a change
of the cis/trans ratio of 3:2 (educts) to 1:1 (products 31a /
b).
The synthesis of the target compounds (Scheme 4)
followed the method originally described by Lindsey et
al. for symmetric porphyrins, which was successfully
applied also for the preparation of unsymmetrical meso-
substituted porphyrins.18 The aldehydes from the pre-
ceding step were reacted with 4-methylbenzaldehyde (33)
and pyrrole (34) in a ratio of 1:3:4 in the presence of
trifluoroacetic acid as catalyst. 28a and 28b were
reduced via catalytic hydrogenation in quantitative yield
to their corresponding hydroquinones 32a and 32b,
respectively, due to a rapid decomposition of the quinone
moieties in the presence of pyrrole and trifluoroacetic acid
yielding a black, tarry product. In a similar case, the
chemical instability of tetrachloro-1,4-benzoquinone in
(18) Lindsey, J . S.; Schreiman, I. C.; Hsu, H. C.; Kearney, P. C.;
Marguerettaz, A. M. J . Org. Chem. 1987, 52, 827-836.
(19) Lindsey, J . S.; MacCrum, K. A.; Tyhonas, J . S.; Chuang, Y.-Y.
J . Org. Chem. 1994, 59, 579-587.

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8669
Sch em e 3. Oxid a tion of th e Alcoh ols to th e Cor r esp on d in g Ald eh yd es
the presence of pyrrole and acid was reported earlier.19
The porphyrin quinones were obtained in 5-13% yield
after repeated purification by column chromatography
and HPLC. No cis-trans isomerization of the acid-
sensitive cis-aldehydes 29a and 30a took place, since both
cis-porphyrin quinones 35a and 36a were formed iso-
merically pure. The separation of the diastereomers 37a
and 37b was achieved by HPLC.
Insertion of zinc into the porphyrin core was performed
using the “acetate method” with zinc(II) acetate in a
mixture of dichloromethane and methanol with nearly
quantitative yields.20,34 Under these conditions 38a and
38b decomposed, presumably due to addition of methanol
or acetate ions to the electron-deficient double bonds of
the quinone. After modification of the reaction conditions
these zinc porphyrin quinones were obtained in about
90% yield by reacting the porphyrin quinones 38a or 38b
with an excess of zinc oxide in the presence of a catalytic
amount of trifluoroacetic acid.
axial and an equatorial (3-5 Hz), two equatorial (2-4
Hz), and two geminally grouped protons (11-15 Hz),
respectively, gave rise to characteristic coupling patterns
that enabled us to discriminate unambiguously between
the cis and trans diastereomers. The most characteristic
coupling patterns were observed for the protons con-
nected to the cyclohexane ring carbons bearing the
substituents, i.e., to C-1 and C-4, respectively. If both
protons bound to C-1 and C-4 are in an axial position
(designated as Ha-1 and Ha-4, respectively), which is true
for all trans isomers, a well-resolved triplet of triplets
due to a large coupling constant of ca. 12 Hz with the
axial neighbor protons and a smaller one of ca. 3.5 Hz
with the equatorial protons bound to the adjacent ring
1
carbons appears in the H NMR spectrum both for Ha-1
and Ha-4. In the corresponding cis isomers (apart from
37a , see below) the proton bound to C-1 is in an axial
position (Ha-1), whereas the proton connected to C-4 is
equatorially bound (He-4). The signal assigned to Ha-1
is a triplet of triplets, for the same reason as it is in the
case of the corresponding trans isomer. On the contrary,
however, the coupling pattern of He-4 results in a broad
multiplet due to vicinal couplings with the axial and
equatorial neighbor protons which are of nearly equal
magnitude and cannot be resolved.
Str u ctu r es a n d Con for m a tion s. The cis and trans
stereochemistry of the diastereomers was investigated
with 1H NMR spectroscopy. The assignments were
confirmed by 1H-1H COSY and selective decoupling
experiments. The results for 15a , 15b, 24a , 24b, 37a ,
and 37b are compiled in Table 1.
The different coupling patterns show clearly, as ex-
pected, the chair conformation for 15a , 15b, 24a , and
24b. The larger (hydro)quinone substituent bound to the
In particular, the different magnitudes of vicinal and
geminal couplings21 between two axial (9-13 Hz), an
(20) Fuhrhop, J .-H.; Smith, K. M. In Porphyrins and Metallopor-
phyrins; Smith, K. M., Ed.; Elsevier: New York, 1975; p 233.
(21) Booth, H. Prog. NMR Spectrosc. 1969, 5, 149-381.

8670 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
Ta ble 1. δH Va lu es (p p m ) a n d Cou p lin g Con sta n ts (Hz) of th e Cycloh exylen e P r oton s fr om 15a , 15b, 24a , 24b, 37a ,
a n d 37b
proton(s)
Ha-1
15a
15b
24a
24b
37a
37b
2.82 (tt)
2.65 (tt)
3.06 (tt)
2.98 (tt)
5.47 (tt)
3J 1 ) 11.0
3J 2 ) 7.2
3.50 (m)
5.38 (tt)
3J aa ) 12.5
3J aa ) 12.5
3J aa ) 12.5
3J aa ≈ 12
3J aa ) 12.5
3J ae ) 3.3
3J ae ) 3.3
3J ae ) 3.6
3J ae ≈ 3
3J ae ) 3.4
Ha-2, Ha-6
He-2, He-6
Ha-3, Ha-5
He-3, He-5
Ha-4
2.01 (qd)
1.97 (qd)
2.34 (qd)
2.30 (qd)
3.24 (qd)
2J ae ) 3J aa ) 13.2
2J ae ) 3J aa ) 13.1
2J ae ) 3J aa ) 13.0
2J ae ) 3J aa ) 12.5
2J ae ) 3J aa ) 12.8
3J ae ) 3.5
3J ae ) 3.7
3J ae ) 3.6
3J ae ) 3.6
3J ae ) 3.4
1.38 (br d)
2J ae ) 13.4
1.59 (br d)
2J ae ) 13.2
1.40 (dq)
1.63 (dq)
2.71 (m)
2.66 (m)
2.10 (m)
2.88 (br d)
2J ae ) 13.6
2J ae ) 13.4
3J ae ) 3J ee ) 3.2
1.58 (tt)
2J ae ) 13.0
3J ae ) 3J ee ) 3.6
1.07 (qd)
1.48 (tt)
1.44 (qd)
2.72 (qd)
2J ae ) 3J aa ) 13.5
2J ae ) 3J aa ) 12.9
2J ae ) 3J aa ) 13.8
2J ae ) 3J aa ) 12.5
2J ae ≈ 14
3J ae ) 4.3
3J ae ) 3.3
3J ae ) 3.9
3J ae ) 3.6
2.21 (br d)
2J ae ) 14.0
2.04 (br d)
2J ae ≈ 14
1.86 (dq)
1.90 (dq)
2.10 (br d)
2J ae ) 13.8
3J ae ) 3J ee ) 3.5
2J ae ) 13.9
3J ae ) 3J ee ) 3.2
1.60 (m)
2J ae ) 13.5
2.37 (tt)
3.44 (tt)
3J aa ) 12.3
3J ae ) 3.4
3J aa ) 12.0
3J ae ≈ 3
He4a
2.66 (m)
1.92 (m)
3.61 (tt)
3J 1 ) 9.6
3J 2 ) 7.2
a
Pseudoaxially positioned in the case of 37a .
Sch em e 4. Syn th esis of th e P or p h yr in Qu in on es.
Ald eh yd es 31a a n d 31b Wer e Rea cted a s a Mixtu r e
of Both Dia ster eom er s. Th e Resu ltin g P or p h yr in
Qu in on es, 37a a n d 37b, Wer e Sep a r a ted by HP LC
ent as well from the size and the alternating sign of the
torsion angles, which are typical of cyclohexane deriva-
tives in a chair conformation (Figure 3). The average
value of 52° deviates from the corresponding value of 56°
for unsubstituted cyclohexane, thus indicating a slightly
flattened ring. The least-squares plane of the cyclohex-
ane ring is orientated perpendicular to the N4-plane of
the porphyrin (dihedral angle 88.2°) and to the quinone
(dihedral angle 89.5°). Both chromophores are positioned
nearly in the same plane (dihedral angle 5.8°). The
center-to-center distance between the porphyrin and
quinone rings amounts to 10.80 Å.
A completely different situation was observed for the
cis-porphyrin quinone 37a . Here, the magnitude of the
coupling constants deviates strongly from the corre-
sponding ones of the cis-substituted precursor 15a (see
Table 1). Especially, the vicinal couplings of the protons
Ha-1 and He-4 at the positions connecting the porphyrin
and quinone substituents (C-1 and C-4) are of equal order
of magnitude (Ha-1, 11.0 and 7.2 Hz; He-4, 9.6 and 7.2
Hz) and thus incompatible with a chair conformation of
the cyclohexylene bridge. Similar couplings were ob-
1
served in the H NMR spectrum of cis-1,4-di-tert-butyl-
cyclohexane indicating a twist-boat conformation of the
cyclohexane ring.22 Force-field calculations23 corrobo-
rated these spectroscopic results.
The molecular structure of 36a , a cis-porphyrin quino-
ne with a different quinone moiety than that of 37a , is
shown in Figure 4. The magnitude and the order of signs
of the torsion angles of unsubstituted cyclohexane in a
twist-boat conformation compared to the corresponding
torsion angles of 36a (Figure 5) show unequivocally that
both the porphyrin and quinone take pseudoequatorial
positions24 of the cyclohexane ring in a twist-boat con-
formation. Obviously, the quinone is too bulky for an
axial position in the chair conformation of the cyclohex-
ane ring. Thus, the cis-porphyrin quinones exist in the
energetically more favored twist-boat conformation, which
ring carbon C-1 resides in the equatorial position in each
compound, whereas the smaller ester and hydroxymethyl
group bound to the ring carbon C-4 takes the axial
position in 15a and 24a (cis diastereomers) and the
equatorial position in 15b and 24b (trans diastereomers),
respectively. Likewise, both the bulky porphyrin (bound
to C-1) and the quinone substituents (bound to C-4) are
arranged in the energetically favored equatorial positions
of the trans-porphyrin quinone 37b.
(22) Remijnse, J . D.; van Bekkum, H; Wepster, B. M. Recl. Trav.
Chim. Pays-Bas 1974, 93, 93-98.
(23) van de Graaf, B.; Baas, J . M. A.; Wepster, B. M. Recl. Trav.
Chim. Pays-Bas 1978, 97, 268-273.
(24) For stereochemistry of the twist-boat conformation and the
distinction between pseudoequatorial, pseudoaxial, and isoclinal posi-
tions, see: Bucourt, R. Top. Stereochem. 1974, 8, 159-224. Kellie, G.
M.; Riddell, F. G. Top. Stereochem. 1974, 8, 225-269.
The molecular structure of 36b, determined by X-ray
crystallography, is shown in Figure 2. 36b is a trans-
porphyrin quinone with similar structure compared to
37b, but with a different quinone moiety. The cyclohex-
ane ring adopts the chair conformation as was also
1
deduced from H NMR spectroscopy. This is also appar-

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8671
F igu r e 2. View of the molecular structure of the porphyrin quinone 36b. Hydrogens have been omitted for clarity.
structures of 1,2,3,4-tetrasubstituted cyclohexanes in a
twist-boat conformation are known.25 Results similar to
those from the crystal structures were obtained with a
MNDO (MOPAC 6.0) calculation35 for the structure of Zn -
37a , which revealed a twist-boat conformation as the
minimum of energy.
Since the PET properties are governed not only by
parameters such as the driving force of the PET reaction
and distance of donor and acceptor etc. but also by the
mutual orientation of the electron donor and acceptor,1
F igu r e 3. (a) Torsion angles of the cyclohexane ring of 36b
information about their relative spatial arrangement are
(P ) porphyrin; MQ ) 2-methyl-1,4-naphthoquinone). (b) For
of utmost importance. Thus, NOE experiments were
undertaken with 37a and 37b to gain insight into the
conformation of the target molecules in solution.
comparison, the torsion angles24 of cyclohexane in the chair
conformation.
NOE measurements with 37b showed NOEs of 15-
20% for the signals of the spatially neighboring protons
(Figure 6) from the porphyrin ring and that of the
cyclohexylene bridge confirming a perpendicular orienta-
tion of the cyclohexane ring relative to porphyrin plain.
This arrangement was also found in the molecular
structure of the structurally related compound 36b (see
above). Additionally, NOEs of 5 and 12%, respectively,
were observed for the signal of the quinoid methyl group
when the signal of the axial cyclohexane protons Ha-4
and Ha-3/Ha-5 was irradiated. These results indicate the
could account for the unexpected NMR spectroscopic
results. Whereas the conformation of the cyclohexane
ring is totally different for both diastereomers, the
remaining conformational properties resemble those of
the trans isomer. The least-squares plane of the cyclo-
hexane ring is nearly perpendicularly orientated to the
plane of the porphyrin (N4-plane) and to the quinone
(dihedral angles 83.9° and 84.5°, respectively). Both
chromophores are nearly coplanar (dihedral angle 6.7°)
with a center-to-center separation of 10.72 Å; this is
nearly the same value as found for the trans isomer.
As far as we are aware, the molecular structure of 36a
is the only example for a cis-1,4-disubstituted cyclohex-
ane existing in a twist-boat conformation, whereas crystal
(28) Weinstock, L. M.; Tull, R.; Handelsmen, B.; Schoenewaldt, E.
F. J . Chem. Eng. Data 1967, 12, 154-155. Minami, N.; Kijima, N.
Chem. Pharm. Bull. 1980, 28, 1648-1650.
(29) Yale, H. L. J . Am. Chem. Soc. 1957, 79, 4762-4765.
(30) Senge, M. O.; Speck, M.; Wiehe, A.; Dieks, H.; Aguirre, S.;
Kurreck, H. Manuscript in preparation.
(31) Fieser L. F.; Ardao, M. I. J . Am. Chem. Soc. 1956, 78, 774-
778.
(32) Whalley, W. B. J . Chem. Soc. 1949, 3016-3020.
(33) Barnett, G. H.; Hudson, M. F.; Smith, K. M. J . Chem. Soc.,
Perkin Trans. 1 1975, 1401-1403.
(34) Fuhrhop, J .-H.; Smith, K. M., ref 20, p 798.
(35) Kirste, B. Unpublished results, 1992.
(25) Bellucci, G.; Berti, G.; Colapietro, M.; Spagna, R.; Zambonelli,
L. J . Chem. Soc., Perkin Trans. 2 1976, 1213-1218. Columbus, I;
Hoffman, R. E.; Biali, S. E. J . Am. Chem. Soc. 1996, 118, 6890-6896.
(26) Kirste, B.; Niethammer, D.; Tian, P.; Kurreck, H. Appl. Magn.
Reson. 1992, 3, 1-18. Kurreck, H.; Tian, P.; von Gersdorff, J .; Newman,
H.; Schubert, H.; Stabingis, T.; Wiehe, A.; Sobek, J . Appl. Magn. Reson.
1994, 6, 17-27. Niethammer, D. Unpublished results, 1995.
(27) Fieser, L. F.; Campbell, W. P.; Fry, E. M.; Gates, M. D., J r. J .
Am. Chem. Soc. 1939, 61, 3216-3223.

8672 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
F igu r e 4. View of the molecular structure of the porphyrin quinone 36a . Hydrogens have been omitted for clarity.
F igu r e 5. (a) Torsion angles of the cyclohexane ring of 36a
(P ) porphyrin; MQ ) 2-methyl-1,4-naphthoquinone). (b) For
comparison, the torsion angles of cyclohexane24 in the twist-
boat conformation.
existence of two conformers differing only in the orienta-
tion of the quinone ring relative to the cyclohexane
moiety. A rapid interconversion of the rotamers takes
place in solution. Such conformers were also detected
in solution (2-propanol) by our ESR, electron nuclear
double resonance (ENDOR), and ENDOR-induced EPR
spectroscopical experiments of paramagnetic species
(semiquinone-anion radicals) which were derived from
cis- and trans-porphyrin quinones and some of their
precursors.7,26
NOE experiments with the cis isomer 37a (Figure 7)
gave NOEs of 5 and 2% for the signal of the porphyrin
proton H-3 and for the pseudoaxial proton Ha-4, respec-
F igu r e 6. NOE experiments with 37b.
tively, revealing a close vicinity of Ha-1 and the porphyrin
ring and of Ha-4 and the quinoid methyl group. Two
different orientations of the quinone ring relative to the
cyclohexylene bridge, as was established for the corre-
sponding trans isomer with NOE experiments, could not
be found. However, the existence of such rotamers could
be deduced not only from the results of MNDO (MOPAC
6.0) calculations35 but also from ESR and ENDOR
measurements as was already mentioned before. The
NOE of 3% for the signal of Ha-4 irradiating the signal
of Ha-1 is indicative of a twist-boat conformation, since
the distance of both protons would be too great in a chair
conformation for an NOE to be observable.
In conclusion, the synthesis of new 1,4-cyclohexylene-
bridged cis- and trans-porphyrin quinones with variable
acceptor strengths and their characterization by 1H NMR
spectroscopy and single-crystal X-ray crystallography has
been described. These compounds are valuable objects

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8673
Sod iu m 4-[4-Hyd r oxy-2-(tr iflu or om eth yl)p h en yla zo]-
ben zen esu lfon a te (7). A precooled (15 °C) solution of 79.0
g (0.46 mol) of 4-aminobenzene sulfonic acid, 24.4 g (0.23 mol)
of sodium carbonate, and 35 g (0.5 mol) of sodium nitrite in
450 mL of water was added to a mixture of 550 g of ice and 96
mL (1.15 mol) of hydrochloric acid (37%, w/w). After 30 min
of standing in an ice bath, the suspension of 6 was gradually
added at 0-5 °C to a solution of 67 g (0.41 mol) of 3-(trifluo-
romethyl)phenol (5) and 32.8 g sodium hydroxide in 300 mL
of water. After addition of sodium chloride the reddish brown
product was filtered off, dried, and used for the next step
without further purification. An analytical sample was ob-
tained after 2-fold recrystallization from water, mp > 350 °C.
1H NMR (250 MHz, DMSO-d6): δ 7.16 (dd, J ) 7.5 Hz, 2.5
Hz, 1H), 7.26 (d, J ) 2.5 Hz, 1H), 7.80 (s, 4H), 7.84 (d, J ) 7.5
Hz, 1H). 19F NMR (DMSO-d6): δ -55.9 (s). UV (water): λmax
(log ꢀ) 234 (4.17), 350 (4.54), 430 (sh) (3.54) nm. FABMS: m/z
(%) 391 (20) ([M + Na]+), 367 (35) ([M - H]-), 345 (100) ([M -
Na]-). Anal. Calcd for C13H8F3N2NaO4S‚2.5H2O: C, 37.78;
H, 3.17; N, 6.78. Found: C, 37.82; H, 3.04; N, 6.66.
F igu r e 7. NOE experiments with 37a .
4-Am in o-3-(tr iflu or om eth yl)p h en ol (8). A vigorously
stirred suspension of the azo dye 7 in 1000 mL of water was
warmed to 50 °C, and 300 g (1.7 mol) of sodium hyposulfite
was added in portions. After the solution was cooled to 20
°C, the product was filtered off, washed with cold water, and
dried. After sublimation (0.1 mbar/85 °C bath temperature)
47.2 g of the product (65% corresponding to 5) was obtained,
mp 158 °C (lit.32 mp 158 °C). 1H NMR (250 MHz, DMSO-d6):
δ 4.88 (br s, 2H), 6.78 (m, 3H), 8.94 (s, 1H). 19F NMR (DMSO-
d6): δ -60.9 (s).
2-(Tr iflu or om eth yl)-1,4-ben zoqu in on e (9). A solution of
11.6 g (65.2 mmol) of 4-amino-3-(trifluoromethyl)phenol (8) in
120 mL of 2.5 M sulfuric acid was added at 5 °C to a
suspension of 13.0 g (150 mmol) of manganese(IV) oxide in
120 mL of 2.5 M sulfuric acid over the course of 3 h. After 2
h of stirring at 5 °C and filtration, the residue was extracted
five times with 200 mL of hexane each. The combined hexane
fractions were cooled to -95 °C and allowed to stand for 1 h.
After filtration and drying 4.2 g (35%) of the product was
obtained which was sufficiently pure for the next step. Hint:
The product is very volatile and should be kept at -30 °C.
For analytical purposes 200 mg was sublimed at 15 mbar/40
°C bath temperature and 15 mbar/rt, mp 54-55 °C (lit.9 mp
54-55 °C), Rf (TLC, dichloromethane) ) 0.8. 1H NMR (250
MHz, CDCl3): δ 6.94 (m, 2H), 7.14 (m, 1H). 13C NMR (62.5
for several interesting spectroscopical investigations
concerning the kinetics of the PET reaction, e.g. forma-
tion and decay of the charge-separated biradical state
with time-resolved picosecond fluorescence and time-
resolved EPR or transient absorption spectroscopy. Work
in this field is already proceeding.
Exp er im en ta l Section
In str u m en ta tion . Conditions and instruments for 1H
NMR, 13C NMR, UV, and mass spectra, elemental analysis,
and melting points were described in a previous publication.3
19F NMR spectra, J EOL FX 90 Q-spectrometer, internal
standard, fluorotrichloromethane. Chromatography: TLC,
glass plates with silica gel 60 coating (0.25 mm) and fluores-
cence indicator (Merck). Flash-column chromatography: silica
gel 60 (Merck, 0.040-0.063 mm, 230-400 mesh). Preparative
HPLC: Waters Delta Preparative Chromatography System
3000 or Knauer modul systems (HPLC Pump 64, MPLC Pump;
variable wavelength detector Nr. A0293). Analytical HPLC
for purity control: modul systems with Gynkotek SP-6-detector
and Waters 510-HPLC Pump or Knauer Pump 64 and Knauer
variable wavelength detector Nr. A0293. Mobile and station-
ary phases are specified below in the individual experimental
descriptions.
MHz, CDCl3): δ 120.41 (q, J C-F ) 277 Hz), 134.60 (q, J C-F
)
Ed u cts. 2-methyl-1,4-naphthoquinone (2),27 2,3-dimethoxy-
5-methyl-1,4-benzoquinone (3),28 and 1,4-cyclohexanedicar-
bonic acid monomethyl ester (12a /b) (4:1 cis/trans mixture)29
were prepared according to established procedures. All other
educts were purchased from Aldrich, Fluka, or Merck and, if
necessary, purified applying standard methods.
4.8 Hz), 135.30 (q, J C-F ) 31.4 Hz), 136.47 (s), 137.02 (s),
181.42 (s), 185.55 (s). 19F NMR (CDCl3): δ -66.4 (s).
(()-tr a n s-5,6-Dibr om o-2-(tr iflu or om eth yl)cycloh ex-2-
en e-1,4-d ion e (10). Bromine (4 g, 25 mmol, 1.3 mL) was
added to a solution of 4.05 g (23 mmol) 9 in 50 mL of
dichloromethane. After the solution was stirred for 2.5 h at
rt, the solvent was evaporated and the colorless residue dried.
Yield: 7.7 g (quantitative yield). The product is sufficiently
pure for the next step. For analysis 100 mg of the crude
product was sublimed at 0.1 mbar/65 °C bath temperature and
0.1 mbar/rt, mp 89-90 °C, Rf (TLC, dichloromethane) ) 0.8.
1H NMR (500 MHz, CDCl3): δ 4.86 (dd, J ) 3.0, 1.90 Hz, 1H),
4.88 (d, J ) 3.0 Hz, 1H), 7.05 (m, J ) 1.90 Hz, 0.95 Hz, 1H).
19F NMR (CDCl3): δ -67.0 (s). EIMS: m/z (%) 334 (6)
[M+(79Br)], 255 (100) [M+(79Br) - 79Br]. HRMS: calcd for C7H3-
Br2F3O2 333.84522, found 333.84554. Anal. Calcd for
C7H3Br2F3O2: C, 25.03; H, 0.90. Found: C, 24.94; H, 0.95.
Cr ysta l Str u ctu r e Deter m in a tion s. 36a : C58H48N4O2‚
2CH2Cl2, at 125 K (Cu KR radiation λ ) 1.54178 Å, 2θmax
)
112.12°), triclinic, space group P1h, a ) 10.652(3), b ) 14.558(5),
and c ) 16.561(5) Å, R ) 94.01(3)°, â ) 91.76(2)°, γ )
103.15(2)°, V ) 2491.8(14) Å,3 Z ) 2, refined against |F2| using
all data, R1 ) 0.120, wR ) 0.27, S ) 1.082 for 6496 reflections
and 629 parameters. 36b: C58H48N4O2‚CH2Cl2 at 126 K (Cu
KR radiation λ ) 1.54178 Å, 2θmax ) 114°), monoclinic, space
group P21/n, a ) 10.388(3), b ) 15.525(4), and c ) 28.804(6)
Å, â ) 98.8(2)°, V ) 4887(2) Å,3 Z ) 4, refined against |F2|
using all data, R1 ) 0.129, wR2 ) 0.322, S ) 1.077 for 6438
reflections and 604 parameters. Full details of the crystal-
lographic studies will be given elsewhere.30
2,3-Dib r om o-5-(t r iflu or om e t h yl)-1,4-d ih yd r oxyb e n -
zen e (11). A total of 50 mL of precooled (0 °C) concentrated
sulfuric acid (98% w/w, F ) 1.84 g/mL) was added to 6.05 g
(18 mmol) of the dibromo adduct 10. After being stirred at
the same temperature for 2.5 h, the reaction mixture was
poured on ice and filtered and the residue was thoroughly
washed with water. After drying and sublimation at 0.1 mbar/
80 °C, 5.3 g (87.7%) product was obtained, mp 145-147 °C, Rf
(TLC, dichloromethane) ) 0.5. 1H NMR (250 MHz, DMSO-
d6): δ 7.14 (s, 1H), 9.66 (s, 1H), 10.60 (s, 1H). 19F-NMR
Tr im eth yl-1,4-ben zoqu in on e (1). Iron(III) chloride (40
g, 145 mmol) was dissolved in 150 mL of water and mixed with
10 g (65.7 mmol) of trimethylhydroquinone in 100 mL of ether.
After the mixture was stirred for 2 h the organic phase was
separated and the aqueous phase extracted with 2 × 50 mL
of ether. After drying (Na2SO4) and filtering of the combined
organic phases, the solvent was evaporated and the residue
was dissolved in dichloromethane and run through a small
column of dry silica gel. After drying 9.2 g (93.5%) of a yellow
solid was obtained, mp 29-30 °C (lit.31 mp 29-30 °C). 1H
NMR (250 MHz, CDCl3): δ 1.94 (s, 3H), 1.96 (s, 3H), 1.97 (d,
J ) 1.6 Hz, 3H), 6.40 (q, J ) 1.6 Hz, 1H).
(DMSO-d6
): δ -62.0 (s). EIMS: m/z (%) 334 (22) [M+(79Br)],
314 (53) [M+(79Br) - HF], 286 (19) [M+(79Br) - CO - HF], 235
(35) [M+(79Br) - 79Br - HF]. HRMS: calcd for C7H3Br2F3O2

8674 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
333.84522, found 333.84504. Anal. Calcd for C7H3Br2F3O2:
C, 25.03; H, 0.90. Found: C, 25.25; H, 0.97.
umn, 32 × 125 mm; stationary phase, Nucleosil 50, 5 µm;
mobile phase, hexane/ethyl acetate 25:1; tR ) 12.6 min (14a );
tR ) 13.6 min (14b); flow rate, 64 mL/min. Analytical HPLC:
column, 4 × 300 mm; stationary phase, Nucleosil 50, 5 µm,
mobile phase, hexane/ethyl acetate 25:1; tR ) 18.7 min (14a );
tR ) 19.7 min; (14b); flow rate, 1.5 mL/min.
2-[4(a )-(Met h oxyca r b on yl)cycloh ex-(e)-yl]-3-m et h yl-
1,4-n a p h th oqu in on e (14a ): mp 117 °C, Rf (TLC, dichlo-
romethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.53 (br d, J
) 13.5 Hz, 2H), 1.61 (tt, J ) 13.5, 3.8 Hz, 2H), 2.22 (qd, J )
13.1, 3.4 Hz, 2H), 2.23 (s, 3H), 2.31 (br d, J ) 14.1 Hz, 2H),
2.77 (m, 1H), 2.82 (tt, J ) 12.5, 3.2 Hz, 1H), 3.80 (s, 3H), 7.69
(m, 2H), 8.03 (m, 2H). EIMS: m/z (%) 312 (100) [M+], 252 (72)
[M+ - CH3OH - CO]. Anal. Calcd for C19H20O4: C, 73.06;
H, 6.45. Found: C, 72.93; H, 6.41.
2-[4(e)-(Met h oxyca r b on yl)cycloh ex-(e)-yl]-3-m et h yl-
1,4-n a p h th oqu in on e (14b): mp 114 °C, Rf (TLC, dichlo-
romethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.53 (qd, J
) 13.0, 3.3 Hz, 2H), 1.68 (br d, J ) 13.5 Hz, 2H), 2.11 (br d, J
) 13.4 Hz, 2H), 2.18 (qd, J ) 13.2, 3.6 Hz, 2H), 2.22 (s, 3H),
2.45 (tt, J ) 12.5, 3.3 Hz, 1H), 2.82 (tt, J ) 12.3, 3.2 Hz, 1H),
3.72 (s, 3H), 7.69 (m, 2H), 8.03 (m, 2H). UV (dichlo-
romethane): λmax (log ꢀ) 242 (4.20), 248 (4.20), 268 (4.20), 274
(4.20), 329 (3.44), 420 (1.87) nm. EIMS: m/z (%) 312 (100)
[M+], 252 (96) [M+ - CH3OH - CO]. Anal. Calcd for
C19H20O4: C, 73.06; H, 6.45. Found: C, 72.81; H, 6.36.
2-[4-(Met h oxyca r b on yl)cycloh exyl]-5,6-d im et h oxy-3-
m eth yl-1,4-ben zoqu in on e (Cis/Tr a n s Mixtu r e 15a /b). Re-
action of 10 g (43.8 mmol) of ammonium peroxodisulfate
dissolved in 100 mL of water, 5 g (27.4 mmol) of the quinone
3, 8 g (43 mmol) of 12a /b, and 1.5 g (8.8 mmol) of silver nitrate,
each dissolved in 50 mL of water and dichloromethane, under
standard conditions gave 3.2 g (35.6%) of a dark red oil after
column chromatography (dichloromethane/ethyl acetate 20:1).
Separation of the diastereomers by preparative HPLC: col-
umn, 32 × 250 mm; stationary phase, Nucleosil 50, 7 µm;
mobile phase, dichloromethane; tR ) 7.06 min (15b); tR ) 8.62
min (15a ); flow rate, 64 mL/min. Analytical HPLC: column,
4 × 120 mm; stationary phase, Eurospher 80, 5 µm; mobile
phase, dichloromethane/water 99.9:0.1; tR ) 1.46 min (15b);
tR ) 1.74 min (15a ); flow rate, 2 mL/min.
2,3-Dibr om o-5-(tr iflu or om eth yl)-1,4-ben zoqu in on e (4).
DDQ (4.1 g, 18 mmol) dissolved in 60 mL of toluene was added
to 5.36 g (16 mmol) of 11 dissolved in 50 mL of ether within
1.5 h. After further stirring for 2 h at rt, the solvent was
removed by distillation, and the residue was dissolved in
dichloromethane and filtered through a short silica gel column.
After evaporation of dichloromethane and sublimation at 0.1
mbar/85 °C bath temperature, 4 was obtained in 90% yield
(4.8 g), mp 162-164 °C, Rf (TLC, toluene/hexane 1:1) ) 0.5.
1H NMR (250 MHz, CDCl3): δ 7.38 (q, J ) 1.0 Hz, 1H). 13C
NMR (62.5 MHz, CDCl3): δ 119.99 (q, J C-F ) 275 Hz), 134.58
(q, J C-F ) 4.8 Hz), 134.97 (q, J C-F ) 31 Hz), 139.78 (s), 140.33
(s), 172.07 (s), 175.89 (s). 19F NMR (CDCl3): δ -66.1 (s). UV
(dichloromethane): λmax (log ꢀ) 251 (4.01), 373 (3.34) nm.
EIMS: m/z (%) 332 (26) [M+(79Br)], 253 (55) [M+(79Br) - 79Br],
225 (61) [M+(79Br) - 79Br - CO], 131 (100) [M+(79Br) - 79Br -
C3HF3 - CO]. HRMS: calcd for C7HBr2F3O2 331.82957, found
331.82938. Anal. Calcd for C7HBr2F3O2: C, 25.18; H, 0.30.
Found: C, 25.25; H, 0.44.
Gen er a l P r oced u r e for th e Ra d ica l Alk yla tion of th e
Qu in on es. The quinone, 12a /b, and silver nitrate were
dissolved in a mixture of equal volumes of water and dichlo-
romethane and heated to reflux. An aqueous solution of
ammonium peroxodisulfate was added within 3-5 h and
heating was continued for 1 h. The organic phase was
separated, the aqueous one was extracted with dichlo-
romethane, and the combined organic phases were dried over
sodium sulfate. After filtration and evaporation of the solvent
the crude product was purified by column chromatography.
In all cases the cis/trans ratio was 3:2. Separation of the
isomers for analytical purposes was achieved by preparative
HPLC.
2-[4-(Meth oxyca r bon yl)cycloh exyl]-3,5,6-tr im eth yl-1,4-
ben zoqu in on e (Cis/Tr a n s Mixtu r e 13a /b). Ammonium per-
oxodisulfate (11.5 g, 50.4 mmol), dissolved in 100 mL of water
and 5 g (33.3 mmol) of the quinone 1, 9.3 g (50 mmol) 12a /b,
1.72 g (10 mmol) of silver nitrate in 50 mL of water, and
dichloromethane each were reacted according to the general
procedure. After column chromatography (eluant: dichlo-
romethane) 5.0 g (51.5%) of a dark yellow oil was obtained.
Separation of the diastereomers by preparative HPLC: col-
umn, 32 × 125 mm; stationary phase, Nucleosil 50, 5 µm;
mobile phase, hexane/ethyl acetate 40:1; tR ) 14.4 min (13a );
tR ) 16.0 min (13b); flow rate, 64 mL/min. Analytical HPLC:
column, 4 × 250 mm; stationary phase, Nucleosil 50, 5 µm;
mobile phase, hexane/ethyl acetate 40:1; tR ) 19.4 min (13a );
tR ) 21.4 min; (13b); flow rate, 1.5 mL/min.
2-[4(a )-(Me t h oxyca r b on yl)cycloh e x-(e )-yl]-3,5,6-t r i-
m eth yl-1,4-ben zoqu in on e (13a ): mp 92-93 °C, Rf (TLC,
dichloromethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.40
(br d, J ) 13.5 Hz, 2H), 1.50 (tt, J ) 13.0, 4.2 Hz, 2H), 1.90 (s,
6H), 2.00 (s, 3H), 2.04 (qd, J ) 13.0 Hz, 3.3 Hz, 2H), 2.22 (br
d, J ) 13.8 Hz, 2H), 2.68 (m, 1H), 2.80 (tt, J ) 12.5, 3.1 Hz,
1H), 3.70 (s, 3H). EIMS: m/z (%) 290 (100) [M+], 230 (70) [M+
- CH3OH - CO]. Anal. Calcd for C17H22O4: C, 70.32; H, 7.63.
Found: C, 70.24; H, 7.63.
2-[4(a )-(Me t h o x y c a r b o n y l)c y c lo h e x -(e )-y l]-5,6-d i-
m eth oxy-3-m eth yl-1,4-ben zoqu in on e (15a ): mp 77-78 °C,
Rf (TLC, dichloromethane/ether 20:1) ) 0.5. 1H NMR (500
2
MHz, CDCl3): δ 1.38 (br d, J 2a2e ) 13.4 Hz, 2H, He-2, He-6),
2
1.48 (tt, J 3a3e ≈ J 2a3a ≈ 13.5 Hz, J 2e3a ≈ J 3a4e ≈ 4.3 Hz, 2H,
2
Ha-3, Ha-5), 2.01 (s, 3H, CH3-quinone), 2.01 (qd, J 2a2e ≈ J 1a2a
≈ J 2a3a ≈ 13.2 Hz, J 2a3e ) 3.5 Hz, 2H, Ha-2, Ha-6), 2.21 (br d,
2J 3a3e ) 14.0 Hz, 2H, He-3, He-5), 2.66 (m, 1H, He-4), 2.82 (tt,
J 1a2a ) J 1a6a ) 12.5 Hz, J 1a2e ) J 1a6e ) 3.3 Hz, 1H, Ha-1), 3.76
(s, 3H, CH3OCO), 3.91 (s, 3H, CH3O), 3.92 (s, 3H, CH3O).
EIMS: m/z (%) 322 (100) [M+], 262 (47) [M+ - CH3OH - CO].
Anal. Calcd for C17H22O6: C, 63.34; H, 6.88. Found: C, 63.32;
H, 6.60.
2-[4(e )-(Me t h o x y c a r b o n y l)c y c lo h e x -(e )-y l]-5,6-d i-
m eth oxy-3-m eth yl-1,4-ben zoqu in on e (15b): mp 65-66 °C,
Rf (TLC, dichloromethane/ether 20:1) ) 0.5. 1H NMR (500
MHz, CDCl3): δ 1.44 (qd, 2J 3a3e ≈ J 2a3a ≈ J 3a4a ≈ 12.9 Hz, J 2e3a
2
2-[4(e )-(Me t h oxyca r b on yl)cycloh e x-(e )-yl]-3,5,6-t r i-
m et h yl-1,4-ben zoq u in on e (13b ): mp 77-78 °C, Rf (TLC,
dichloromethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.46
(qd, J ) 12.6, 3.7 Hz, 2H), 1.58 (br d, J ) 14.0 Hz, 2H), 1.91
(s, 3H), 1.92 (s, 3H), 1.98 (m, 4H), 1.98 (s, 3H), 2.38 (tt, J )
12.2, 3.6 Hz, 1H), 2.64 (tt, J ) 12.5 Hz, 3.5 Hz, 1H), 3.64 (s,
3H). UV (dichloromethane): λmax (log ꢀ) 264 (4.27), 271 (4.26),
) 3.3 Hz, 2H, Ha-3, Ha-5), 1.59 (br d, J 2a2e ) 13.2 Hz, 2H,
2
He-2, He-6), 1.97 (qd, J 2a2e ≈ J 1a2a ≈ J 2a3a ≈ 13.1 Hz, J 2a3e
)
3.7 Hz, 2H, Ha-2, Ha-6), 2.03 (s, 3H, CH3-quinone), 2.04 (br d,
2H, He-3, He-5), 2.37 (tt, J 3a4a ) J 4a5a ) 12.3 Hz, J 3e4a ) J 4a5e
) 3.4 Hz, 1H, Ha-4), 2.65 (tt, J 1a2a ) J 1a6a ) 12.5 Hz, J 1a2e
)
J 1a6e ) 3.3 Hz, 1H, Ha-1), 3.64 (s, 3H, CH3OCO), 3.93 (s, 3H,
CH3O), 3.94 (s, 3H, CH3O). UV (dichloromethane): λmax (log
ꢀ) 280 (4.18), 408 (2.67) nm. EIMS: m/z (%) 322 (100) [M+],
262 (42) [M+ - CH3OH - CO]. Anal. Calcd for C17H22O6: C,
63.34; H, 6.88. Found: C, 63.13; H, 6.70.
344 (2.47) nm. EIMS: m/z (%) 290 (85) [M+], 230 (100) [M+
CH3OH - CO]. Anal. Calcd for C17H22O4: C, 70.32; H, 7.63.
Found: C, 70.24; H, 7.59.
-
2-[4(a )-(Met h oxyca r b on yl)cycloh ex-(e)-yl]-3-m et h yl-
1,4-n a p h th oqu in on e (Cis/Tr a n s Mixtu r e 14a /b). Am-
monium peroxodisulfate (10.3 g, 45 mmol) dissolved in 100 mL
water, and 5 g (29.1 mmol) of the quinone 2, 8.4 g (45 mmol)
12a /b, 1.0 g (5.9 mmol) silver nitrate, each dissolved in 50 mL
water and dichloromethane, were reacted according to the
general procedure. After column chromatography (dichlo-
romethane) 4.6 g (50.7%) of a yellow solid was obtained.
Separation of the diastereomers by preparative HPLC: col-
2,3-Dib r om o-5-[4(a )-(m et h oxyca r b on yl)cycloh ex-(e)-
yl]-6-(tr iflu or om eth yl)-1,4-ben zoqu in on e (Cis/Tr a n s Mix-
tu r e 16a /b). Reaction of 15.0 g (65.7 mmol) of ammonium
peroxodisulfate, dissolved in 100 mL of water, 3 g (8.9 mmol)
of quinone 4, 2.5 g (13.4 mmol) of 12a /b, and 0.5 g (2.9 mmol)
of silver nitrate, each dissolved in 50 mL of water and
dichloromethane following the standard procedure, gave 1.3
g (30%) of a dark yellow oil after column chromatography
(dichloromethane). Separation of the diastereomers by pre-

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8675
parative HPLC: column, 32 × 125 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, hexane/dichloromethane 2:1;
tR ) 21 min (16a ); tR ) 23 min (16b); flow rate, 64 mL/min.
Analytical HPLC: column, 4 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, hexane/dichloromethane 3:2;
tR ) 21.4 min (16a ); tR ) 23.4 min (16b); flow rate, 1.5 mL/
min.
mmol) of lithium borohydride added. After being heated under
reflux for 20 h, the reaction mixture was cautiously hydrolyzed
with water and hydrochloric acid. Subsequently, 100 mL of
ether and within 20 min 100 mL of an aqueous solution of
ammonium cerium(IV) nitrate (23.6 g, 43 mmol) were added.
The ether layer was separated, the aqueous one was extracted
three times with 50 mL of ether, and the combined organic
phases were dried over Na2SO4. After filtration and evapora-
tion of the solvent the yellow residue was purified by column
chromatography (dichloromethane/acetone 10:1) yielding 3.3
g (72%) of product. Separation of the diastereomers with
preparative HPLC: column, 32 × 125 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/ethyl
acetate 97:3; tR ) 12.8 min (25b); tR ) 15 min (25a ); flow rate,
64 mL/min. Analytical HPLC: column, 4 × 250 mm; station-
ary phase, Nucleosil 50, 5 µm; mobile phase, dichloromethane/
ethyl acetate 20:1; tR ) 17.2 min (25b); tR ) 19.8 min (25a );
flow rate, 1.5 mL/min.
2,3-Dib r om o-5-[4(a )-(m et h oxyca r b on yl)cycloh ex-(e)-
yl]-6-(tr iflu or om eth yl)-1,4-ben zoqu in on e) (16a ): mp 116-
118 °C, Rf (TLC, dichloromethane) ) 0.6. 1H NMR (500 MHz,
CDCl3): δ 1.56 (m, 4H), 2.12 (qd, J ) 13.3, 3.7 Hz, 2H), 2.33
(br d, J ) 14.0 Hz, 2H), 2.75 (m, 1H), 3.10 (tt, J ) 12.5, 3.3
Hz, 1H), 3.80 (s, 3H). 13C NMR (62.5 MHz, CDCl3): δ 26.98
(s), 27.24 (s), 38.10 (s), 41.55 (s), 51.88 (s), 121.50 (q, J C-F
)
279 Hz), 131.90 (q, J C-F ) 30 Hz), 139.15 (q, J C-F ) 2 Hz),
139.56 (s), 155.02 (s), 173.39 (s), 174.71 (s), 176.54 (s). 19F
NMR (CDCl3): δ -56.7 (s). EIMS: m/z (%) 472 (11) [M+(79Br)],
412 (47) [M+(79Br) - CH3OH - CO]. HRMS: calcd for C15H13
-
Br2F3O4 471.91330, found 471.91341. Anal. Calcd for
C15H13Br2F3O4: C, 38.00; H, 2.76. Found: C, 38.07; H, 2.75.
2,3-Dib r om o-5-[4(e)-(m et h oxyca r b on yl)cycloh ex-(e)-
yl]-6-(tr iflu or om eth yl)-1,4-ben zoqu in on e (16b): mp 102-
103 °C, Rf (TLC, dichloromethane) ) 0.6. 1H NMR (500 MHz,
CDCl3): δ 1.52 (qd, J ) 13.1, 3.4 Hz, 2H), 1.74 (dq, J ) 13.4,
3.2 Hz, 2H), 2.05 (qd, J ) 13.0, 3.7 Hz, 2H), 2.12 (dq, J ) 13.4,
3.1 Hz, 2H), 2.44 (tt, J ) 12.5, 3.8 Hz, 1H), 3.02 (tt, J ) 12.3,
3.4 Hz, 1H), 3.70 (s, 3H). 13C NMR (62.5 MHz, CDCl3): δ 28.84
2-[4(a)-(Hydr oxym eth yl)cycloh ex-(e)-yl]-3,5,6-tr im eth yl-
1,4-ben zoqu in on e (25a ): mp 91-92 °C, Rf (TLC, dichlo-
romethane/acetone 10:1) ) 0.4. 1H NMR (500 MHz, CDCl3):
δ 1.36 (dq, J ) 13.4, 3.5 Hz, 2H), 1.48 (s, 1H), 1.54 (tt, J )
13.5, 4.2 Hz, 2H), 1.90 (dq, J ) 14.0, 3.4 Hz, 2H), 1.92 (m,
1H), 1.98 (q, J ) 2.0 Hz, 3H), 1.99 (q, J ) 2.0 Hz, 3H), 2.04
(qd, J ) 13.3, 3.6 Hz, 2H), 2.08 (s, 3H), 2.74 (tt, J ) 12.5, 3.4
Hz, 1H), 3.86 (d, J ) 7,5 Hz, 2H). EIMS: m/z (%) 262 (100)
[M+], 244 (42) [M+ - H2O]; 229 (42) [M+ - CH3 - H2O]. Anal.
Calcd for C16H22O3: C, 73.25; H, 8.45. Found: C, 73.24; H,
8.33.
2-[4(e)-(Hydr oxym eth yl)cycloh ex-(e)-yl]-3,5,6-tr im eth yl-
1,4-ben zoqu in on e (25b): mp 73-74 °C, Rf (TLC, dichlo-
romethane/acetone 10:1) ) 0.4. 1H NMR (500 MHz, CDCl3):
δ 1.06 (qd, J ) 12.7, 3.7 Hz, 2H), 1.58 (s, 1H), 1.61 (m, 3H),
1.90 (dq, J ) 14.0, 3.2 Hz, 2H), 1.98 (q, J ) 2 Hz, 3H), 1.99 (q,
J ) 2 Hz, 3H), 3H), 2.01 (qd, J ) 13.0, 3.5 Hz, 2H), 2.08 (s,
3H), 2.70 (tt, J ) 12.5, 3.5 Hz, 1H), 3.50 (d, J ) 7.5 Hz, 2H).
EIMS: m/z (%) 262 (100) [M+], 244 (45) [M+ - H2O]; 229 (39)
[M+ - CH3 - H2O]. Anal. Calcd for C16H22O3: C, 73.25; H,
8.45. Found: C, 73.15; H, 8.35.
(s), 29.33 (s), 41.19 (s), 42.11 (s), 51.71 (s), 121.41 (q, J C-F
)
279 Hz), 132.22 (q, J C-F ) 30 Hz), 139.31 (q, J C-F ) 2 Hz),
139.45 (s), 154.79 (s), 173.24 (s), 175.70 (s), 176.81 (s). 19F
NMR (CDCl3): δ -57.2 (s). UV (dichloromethane): λmax (log
ꢀ) 278 (3.91), 366 (2.99) nm. EIMS: m/z (%) 472 (1) [M+(79Br)],
412 (33) [M+(79Br) - CH3OH - CO], 372 (53) [M+(79Br) - CH3-
OH - CO - 2HF]. HRMS: calcd for C15H13Br2F3O4 471.91330,
found 471.91341. Anal. Calcd for C15H13Br2F3O4: C, 38.00;
H, 2.76. Found: C, 37.93; H, 2.77.
2,3-Dibr om o-5-[4-(m eth oxyca r bon yl)cycloh exyl]-6-(tr i-
flu or om eth yl)-1,4-d ih yd r oxyben zen e (Cis/Tr a n s Mixtu r e
20a /b). Cis/Trans mixture 16a /b (5 g, 10.5 mmol), dissolved
in 100 mL of toluene, was hydrogenated with 50 mg of
palladium catalyst (Pd-C; 10% Pd). After uptake of hydrogen
had ceased, the solution was filtered, the solvent distilled off,
and the remaining colorless oil dried yielding quantitatively
the cis/trans mixture of 20a /b. For analytical purposes, small
amounts of isomerically pure samples of 20a and 20b, respec-
tively, were reduced to the corresponding hydroquinones under
the same conditions as described for the cis/trans mixture of
20a /b.
2,3-Dib r om o-5-[4(a )-(m et h oxyca r b on yl)cycloh ex-(e)-
yl]-6-(tr iflu or om eth yl)-1,4-d ih yd r oxyben zen e (20a ). Es-
ter 16a (50 mg, 0.1 mmol), dissolved in 10 mL of toluene, was
hydrogenated with 5 mg of palladium catalyst in quantitative
yield and worked up as described above. 1H NMR (500 MHz,
CDCl3): δ 1.50 (br d, J ) 13.2 Hz, 2H), 1.58 (tt, J ) 13.4, 4.1
Hz, 2H), 2.28 (br d, J ) 14.0 Hz, 2H), 2.40 (qd, J ) 13.0, 4.1
Hz, 2H), 2.74 (m, 1H), 3.08 (tt, J ) 12.5, 3.5 Hz, 1H), 3.76 (s,
3H), 5.86 (s, 1H), 6.00 (s, 1H). 19F NMR (CDCl3): δ -52.2 (s).
EIMS: m/z (%) 474 (22) [M+(79Br)], 414 (57) [M+(79Br) - CH3-
OH - CO]. HRMS: calcd for C15H15Br2F3O4 473.92895, found
473.92905.
2-[4-(H yd r oxym et h yl)cycloh exyl]-3-m et h yl-1,4-n a p h -
th oqu in on e (Cis/Tr a n s Mixtu r e 26a /b). Esters 14a /b (5
g, 16 mmol) were converted to the corresponding alcohols via
catalytical hydrogenation, reduction of the ester group with
lithium borohydride (1.5 g, 69 mmol), and oxidation of the
hydroquinone with ammonium cerium(IV) nitrate (22 g, 40
mmol) as described for 13a /b. After column chromatography
(dichloromethane/acetone 10:1) 3.4 g (74.7%) of product were
obtained. Separation of the diastereomers with preparative
HPLC: column, 32 × 125 mm; stationary phase, Nucleosil 50,
5 µm; mobile phase, dichloromethane/ethyl acetate 98:2; tR
)
9.3 min (26b); tR ) 10.3 min (26a ); flow rate, 64 mL/min.
Analytical HPLC: column, 4 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/ethyl
acetate 10:1; tR ) 11.8 min (26b); tR ) 12.9 min (26a ); flow
rate, 1.5 mL/min.
2-[4(a )-(Hyd r oxym eth yl)cycloh ex-(e)-yl]-3-m eth yl-1,4-
n aph th oqu in on e (26a): mp 152 °C, Rf (TLC, dichloromethane/
acetone 10:1) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.41 (dq,
J ) 13.9, 3.2 Hz, 2H), 1.50 (s, 1H), 1.58 (tt, J ) 13.7, 4.0 Hz,
2H), 1.92 (dq, J ) 14.0, 3.9 Hz, 2H), 1.99 (m, 1H), 2.21 (qd, J
)13.6, 3.4 Hz, 2H), 2.24 (s, 3H), 2.85 (tt, J ) 12.5, 3.4 Hz,
1H), 3.91 (d, J ) 7.5 Hz, 2H), 7.67 (m, 2H), 8.03 (m, 2H).
EIMS: m/z (%) 284 (100) [M+], 266 (73) [M+ - H2O]; 251 (51)
[M+ - CH3 - H2O]. Anal. Calcd for C18H20O3: C, 76.03; H,
7.09. Found: C, 75.79; H, 6.98.
2-[4(e)-(Hyd r oxym eth yl)cycloh ex-(e)-yl]-3-m eth yl-1,4-
n aph th oqu in on e (26b): mp 124 °C, Rf (TLC, dichloromethane/
acetone 10:1) ) 0.5. 1H NMR (500 MHz, CDCl3): δ 1.11 (qd,
J ) 12.5, 3.8 Hz, 2H), 1.40 (s, 1H), 1.63 (m, 3H), 1.96 (dq, J )
14.0, 3.3 Hz, 2H), 2.14 (qd, J ) 13.3, 3.8 Hz, 2H), 2.22 (s, 3H),
2.84 (tt, J ) 12.5, 3.2 Hz, 1H), 3.52 (d, J ) 7.0 Hz, 2H), 7.70
(m, 2H), 8.06 (m, 2H). EIMS: m/z (%) 284 (100) [M+], 266
(62) [M+ - H2O]; 251 (42) [M+ - CH3 - H2O]. Anal. Calcd
for C18H20O3: C, 76.03; H, 7.09. Found: C, 75.82; H, 7.00.
2-[4-(Hydr oxym eth yl)cycloh exyl]-5,6-dim eth oxy-3-m eth -
yl-1,4-ben zoqu in on e (Cis/Tr a n s Mixtu r e 27a /b). An aque-
ous solution (150 mL) of 25 g (144 mmol) of sodium hyposulfite
2,3-Dib r om o-5-[4(e)-(m et h oxyca r b on yl)cycloh ex-(e)-
yl]-6-(tr iflu or om eth yl)-1,4-d ih yd r oxyben zen e (20b). Es-
ter 16b (50 mg, 0.1 mmol), dissolved in 10 mL of toluene, was
hydrogenated with 5 mg of palladium catalyst in quantitative
yield and worked up as described above. 1H NMR (500 MHz,
CDCl3): δ 1.54 (qd, J ) 13.3, 3.5 Hz, 2H), 1.66 (br d, J ) 13.2
Hz, 2H), 2.08 (br d, J ) 14.0 Hz, 2H), 2.30 (qd, J ) 13.0, 3.6
Hz, 2H), 2.40 (tt, J ) 12.5, 3.2 Hz, 1H), 3.01 (tt, J ) 12.5, 3.2
Hz, 1H), 3.68 (s, 3H), 5.60 (s, 1H), 5.96 (s, 1H). 19F NMR
(CDCl3): δ -52.2 (s). EIMS: m/z (%) 474 (21) [M+(79Br)], 414
(43) [M+(79Br) - CH3OH - CO]. HRMS: calcd for C15H15
Br2F3O4 473.92895, found 473.92882.
-
2-[4-(H yd r oxym et h yl)cycloh exyl]-3,5,6-t r im et h yl-1,4-
ben zoqu in on e (Cis/Tr a n s Mixtu r e 25a /b). 13a /b (5 g, 17.2
mmol), was dissolved in 60 mL of THF, and 100 mg of catalyst
for hydrogenation (Pd-C, 10% Pd) was added. After cessation
of hydrogen uptake, the catalyst was removed and 1.6 g (73.5

8676 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
was added to a solution of 100 mL of 5 g (15.5 mmol) of 15a /b
in dichloromethane and stirring was continued until the
organic phase had turned colorless. The organic phase was
separated, and the aqueous one was extracted three times with
30 mL of dichloromethane. The combined organic phases were
dried over Na2SO4 under an argon atmosphere. After filtration
the solvent was removed, the remaining oil was dissolved in
100 mL of THF, lithium borohydride was added in two portions
of 510 mg each (total 1.02 g, 46.8 mmol), and the solution was
heated under reflux for 20 h. Water, hydrochloric acid (25%
w/w), and 100 mL of ether were added cautiously under cooling
with ice. An aqueous solution (120 mL) of iron(III) chloride
(12.2 g, 45 mmol) was added within 20 min and stirring was
continued for 1 h. The ether phase was separated, the aqueous
one was extracted three times with 30 mL of ether each. After
drying (Na2SO4), filtration, and evaporation of the solvent, the
dark red residue was purified by column chromatography
(dichloromethane/acetone 10:1) yielding 2.6 g (57%) product.
Attempted separation of the diastereomers with preparative
HPLC was unsuccessful. For characterization of 27a and 27b,
the isomerically pure esters 15a and 15b were reduced,
respectively.
2-[4(a)-(Hydr oxym eth yl)cycloh ex-(e)-yl]-5,6-dim eth oxy-
3-m eth yl-1,4-ben zoqu in on e (27a ). With one-tenth of the
reaction scale as described above for the cis/trans mixture, 15a
was reduced to 27a . Yield: 260 mg (56.9%), mp 89-90 °C, Rf
(TLC, dichloromethane/acetone 10:1) ) 0.4. 1H NMR (500
MHz, CDCl3): δ 1.35 (br d, J ) 13.2, 2H), 1.55 (tt, J ) 13.5,
3.6 Hz, 2H), 1.59 (s, 1H), 1.88 (br d, J ) 14.0 Hz, 2H), 1.95
(m, 1H), 2.05 (qd, J ) 12.9, 3.6 Hz, 2H), 2.06 (s, 3H), 2.71 (tt,
J ) 12.5, 3.2 Hz, 1H), 3.84 (d, J ) 7.5 Hz, 2H), 3.98 (s, 3H),
3.99 (s, 3H). EIMS: m/z (%) 294 (100) [M+]. Anal. Calcd for
C16H22O5: C, 65.29; H, 7.53. Found: C, 65.29; H, 7.49.
2-[4(e)-(Hydr oxym eth yl)cycloh ex-(e)-yl]-5,6-dim eth oxy-
3-m eth yl-1,4-ben zoqu in on e (27b). With one-tenth the reac-
tion scale as described above for 15a /b, 15b was reduced to
27b. Yield: 270 mg (59.1%), mp 100-101 °C, Rf (TLC,
dichloromethane/acetone 10:1) ) 0.4. 1H NMR (500 MHz,
CDCl3): δ 1.04 (qd, J ) 12.8, 3.7 Hz, 2H), 1.48 (s, 1H), 1.61
(m, 3H), 1.90 (dq, J ) 13.8, 3.2 Hz, 2H), 1.99 (qd, J ) 12.8, 3.7
Hz, 2H), 2.06 (s, 3H), 2.70 (tt, J ) 12.5, 3.5 Hz, 1H), 3.50 (d,
J ) 7.5 Hz, 2H), 3.98 (s, 3H), 3.99 (s, 3H). EIMS: m/z (%)
294 (100) [M+]. Anal. Calcd for C16H22O5: C, 65.29; H, 7.53.
Found: C, 65.17; H, 7.44.
2,3-Dib r om o-5-[4-(h yd r oxym et h yl)cycloh exyl]-6-(t r i-
flu or om eth yl)-1,4-d ih yd r oxyben zen e (Cis/Tr a n s Mixtu r e
24a /b). A 1 M DIBALH solution (110 mL, 110 mmol) was
added to a solution of 7.5 g (15.8 mmol) of 20a /b in 100 mL of
THF at -50 °C over the course of 40 min. Stirring was
continued for 1 h at the same temperature, and 100 mL of 2
M hydrochloric acid was added. Subsequently the reaction
mixture was warmed to rt, 150 mL of ether was added, and
the organic phase was separated. The aqueous phase was
extracted with five portions of 30 mL of ether each. The
combined organic phases were dried (Na2SO4) and filtered, and
the solvent was removed by distillation yielding 6.6 g (92.7%).
Separation of the diastereomers by preparative HPLC: col-
umn, 32 × 125 mm; stationary phase, Nucleosil 50, 5 µm;
mobile phase, dichloromethane/ethyl acetate 94:6; tR ) 11.2
min (24b); tR ) 13.4 min (24a ); flow rate, 64 mL/min.
Analytical HPLC: column, 4 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/ethyl
acetate 10:1; tR ) 6.9 min (24b); tR ) 9.0 min (24a ); flow rate,
1.5 mL/min.
HRMS: calcd for C14H15Br2F3O3 445.93403, found 445.93415.
Anal. Calcd for C14H15Br2F3O3: C, 37.52; H, 3.37. Found: C,
37.55; H, 3.34.
2,3-Dibr om o-5-[4(e)-(h yd r oxym eth yl)cycloh ex-(e)-yl]-
6-(tr iflu or om eth yl)-1,4-dih ydr oxyben zen e (24b): mp 139-
140 °C, Rf (TLC, dichloromethane/acetone 10:1) ) 0.4. 1H
2
NMR (500 MHz, CDCl3): δ 1.07 (qd, J 3a3e ≈ J 2a3a≈ J 3a4a
≈
12.5 Hz, J 2e3a ) 3.6 Hz, 2H, Ha-3, Ha-5), 1.38 (s, 1H, CH2OH),
2
1.60 (m, 1H, Ha-4), 1.63 (dq, J 2a2e ) 13.0 Hz, J 1a2e ≈ J 2e3a
≈
J 2e3e ≈ 3.6 Hz, 2H, He-2, He-6), 1.90 (dq, 2J 3a3e ) 13.9 Hz, J 2a3e
≈ J 2e3e ≈ J 3e4a ≈ 3.2 Hz, 2H, He-3, He-5), 2.30 (qd, 2J 2a2e ≈ J 1a2a
≈ J 2a3a ≈ 12.5 Hz; J 2a3e ) 3.6 Hz, 2H, Ha-2, Ha-6), 2.98 (tt,
J 1a2a ) J 1a6a ≈ 12 Hz, J 1a2e ) J 1a6e ≈ 3 Hz, 1H, Ha-1), 3.51 (d,
J ) 7.0 Hz, CH2OH), 5.60 (s, 1H, OH), 5.94 (s, 1H, OH). 19F-
NMR (CDCl3): δ -52.2 (s). EIMS: m/z (%) 446 (49) [M+(79Br)],
428 (18) [M+(79Br) - H2O], 360 (35) [M+(79Br) - C5H8 - H2O].
HRMS: calcd for C14H15Br2F3O3 445.93403, found 445.93415.
Anal. Calcd for C14H15Br2F3O3: C, 37.52; H, 3.37. Found: C,
37.43; H, 3.29.
2-[4(a )-F or m ylcycloh ex-(e)-yl]-3,5,6-tr im eth yl-1,4-ben -
zoqu in on e (29a ). 25a (0.71 g, 2.7 mmol), 0.014 g (0.09 mmol)
of TEMPO, and 0.35 g (3 mmol) of potassium bromide were
dissolved in a two-phase system of 8 mL of dichloromethane
and 4 mL of water. After the solution was cooled to 0 °C, 3.5
mL of a sodium hypochlorite solution was added within 20 min
in several portions under vigorous stirring. The pH of the
sodium hypochlorite solution was adjusted with sodium hy-
drogencarbonate to 8.5 prior to addition. Potassium iodide (2
g) (in 3 mL of water) and subsequently 2.5 g of sodium
thiosulfate (in 5 mL of water) were added. The organic phase
was separated, and the aqueous one was extracted with 5 mL
of dichloromethane. After drying over sodium sulfate, filtra-
tion, and removal of the solvent, 0.7 g (98.7%) of the aldehyde
was obtained as a yellow oil. A pure sample of the aldehyde
for elemental analysis could not be obtained, since attempted
purification by chromatography or by recrystallization from
hexane yielded a partially cis/trans isomerized or an oily
product, respectively. However, the crude product was suf-
ficiently pure for the reaction in the next step: Rf (TLC,
dichloromethane/ether 50:1) ) 0.5. 1H NMR (250 MHz,
CDCl3): δ 1.50 (br d, 2H), 1.68 (tt, 2H), 1.98 (s, 3H), 1.99 (s,
3H), 2.00 (qd, 2H), 2.04 (s, 3H), 2.38 (br d, 2H), 2.56 (m, 1H),
2.82 (tt, 1H), 9.84 (s, 1H). EIMS: m/z (%) 260 (100) [M+], 242
(13) [M+ - H2O]. HRMS: calcd for C16H20O3 260.14125, found
260.14120.
2-[4(e)-F or m ylcycloh ex-(e)-yl]-3,5,6-tr im eth yl-1,4-ben -
zoqu in on e (29b). Using the conditions described for 29a ,
0.85 g (3.23 mmol) of 25b, 0.017 g (0.11 mmol) of TEMPO,
and 0.39 g (3.25 mmol) of potassium bromide in a two-phase
system of 10 mL of dichloromethane and 5 mL of water were
treated with 4.5 mL of sodium hypochlorite (12%). Workup
as described above gave 0.73 g (86%) of 29b as a yellow oil. A
pure sample of the aldehyde for elemental analysis could not
be obtained, since attempted purification by chromatography
or by recrystallization from hexane yielded a partially cis/trans
isomerized or an oily product, respectively. However, the
crude product was sufficiently pure for the reaction in the next
step: Rf (TLC, dichloromethane/ether 50:1) ) 0.5. 1H NMR
(250 MHz, CDCl3): δ 1.34 (qd, 2H), 1.58 (br d, 2H), 1.98 (s,
3H), 1.99 (s, 3H), 2.04 (m, 4H), 2.08 (s, 3H), 2.36 (tt, 1H), 2.70
(tt, 1H), 9.68 (s, 1H). EIMS: m/z (%) 260 (100) [M+], 242 (60)
[M+ - H2O], 230 (78) [M+ - CHO - H]. HRMS: calcd for
C16H20O3 260.14125, found 260.14120.
2-[4(a )-F or m ylcycloh ex-(e)-yl]-3-m et h yl-1,4-n a p h t h o-
qu in on e (30a ). Analogous to the synthesis of 29a , 1.0 g (3.5
mmol) of 26a , 0.013 g (0.08 mmol) of TEMPO, and 0.03 g (0.25
mmol) of potassium bromide in a two-phase system of 10 mL
of dichloromethane and 5 mL of water were treated with 3.5
mL of sodium hypochlorite (12%). Workup as described for
29a yielded 0.84 g (85%) of 30a , which was recrystallized from
hexane, mp 144 °C, Rf (TLC, dichloromethane/ether 50:1) )
0.5. 1H NMR (250 MHz, CDCl3): δ 1.54 (br d, 2H), 1.68 (tt,
2H), 2.08 (qd, 2H), 2.20 (s, 3H), 2.36 (br d, 2H), 2.56 (m, 1H),
2.96 (tt, 1H), 7.64 (m, 2H), 8.00 (m, 2H), 9.84 (s, 1H). EIMS:
m/z (%) 282 (100) [M+]. Anal. Calcd for C18H1803: C, 76.57;
H, 6.43. Found: C, 76.46; H, 6.44.
2,3-Dibr om o-5-[4(a )-(h yd r oxym eth yl)cycloh ex-(e)-yl]-
6-(tr iflu or om eth yl)-1,4-dih ydr oxyben zen e (24a): mp 122-
123 °C, Rf (TLC, dichloromethane/acetone 10:1) ) 0.4. 1H
NMR (500 MHz, CDCl3): δ 1.37 (s, 1H, CH2OH), 1.40 (dq, 2J 2a2e
) 13.4 Hz, J 1a2e ≈ J 2e3a ≈ J 2e3e ≈ 3.2 Hz, 2H, He-2, He-6), 1.58
2
(tt, J 3a3e ≈ J 2a3a ≈ 13.8 Hz, J 2e3a ≈ J 3a4e ≈ 3.9 Hz, 2H, Ha-3,
2
Ha-5), 1.86 (dq, J 3a3e ) 13.8 Hz, J 2a3e ≈ J 2e3e ≈ J 3e4e ≈ 3.5 Hz,
2
2H, He-3, He-5), 1.92 (m, 1H, He-4), 2.34 (qd, J 2a2e ≈ J 1a2a
≈
J 2a3a ≈ 13.0 Hz, J 2a3e ) 3.6 Hz, 2H, Ha-2, Ha-6), 3.06 (tt, J 1a2a
) J 1a6a ) 12.5 Hz, J 1a2e ) J 1a6e ) 3.6 Hz, 1H, Ha-1), 3.85 (d, J
) 7.5 Hz, 2H, CH2OH), 5.78 (s, 1H, OH), 5.98 (s, 1H, OH). 19
F
NMR (CDCl3): δ -52.1 (s). EIMS: m/z (%) 446 (13) [M+(79Br)],
428 (32) [M+(79Br) - H2O], 360 (50) [M+(79Br) - C5H8 - H2O].

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8677
2-[4(e)-F or m ylcycloh ex-(e)-yl]-3-m et h yl-1,4-n a p h t h o-
qu in on e (30b). Reaction scale and workup was as described
for 30a . Yield: 0.82 g (83%) of 30b, Rf (TLC, dichloromethane/
ether 50:1) ) 0.5. A pure sample of the aldehyde for elemental
analysis could not be obtained, since attempted purification
by chromatography or by recrystallization from hexane yielded
a partially cis/trans isomerized or an oily product, respectively.
However, the crude product was sufficiently pure for the
reaction in the next step. 1H NMR (250 MHz, CDCl3): δ 1.24
(qd, 2H), 1.64 (br d, 2H), 2.08 (m, 4H), 2.12 (s, 3H), 2.32 (tt,
1H), 2.74 (tt, 1H), 7.52 (m, 2H), 8.84 (m, 2H), 9.56 (s, 1H).
EIMS: m/z (%) 282 (100) [M+]. HRMS: calcd 282.12560, found
282.12529.
tallization from hexane yielded no analytically pure product.
However, the crude product was sufficiently pure for the
reaction in the next step. Rf (TLC, dichloromethane/ether 50:
1) ) 0.6. 1H NMR (250 MHz, CDCl3): δ 1.52 (br d, 2H), 1.68
(tt, 2H), 2.32 (m, 4H), 2.52 (m, 1H), 3.04 (tt, 1H), 5.70 (s, 1H),
6.04 (s, 1H), 9.80 (s, 1H). 19F NMR (CDCl3): δ -52.2 (s).
EIMS: m/z (%) 444 (50) [M+(79Br)], 426 (47) [M+(79Br) - H2O].
HRMS: calcd for C14H13Br2F3O3 443.91838, found 443.91845.
2,3-Dib r om o-5-[4(e)-for m ylcycloh ex-(e)-yl]-6-(t r iflu o-
r om eth yl)-1,4-ben zoqu in on e (28b). 24b (1.5 g, 3.4 mmol)
was oxidized with 3.6 g of (16.9 mmol) PCC as described for
24a . The aldehyde (1.1 g, 73%) was obtained as a yellow oil.
Cis/trans ratio (from 1H NMR spectrum): 5:95. Rf (TLC,
dichloromethane/ether 50:1) ) 0.7. 1H NMR (250 MHz,
CDCl3): δ 1.36 (qd, 2H), 1.82 (br d, 2H), 2.12 (m, 4H), 2.44 (tt,
1H), 3.04 (tt, 1H), 9.54 (s, 1H). 19F NMR (CDCl3): δ -57.2
(s). EIMS: m/z (%) 442 (29) [M+(79Br)], 424 (17) [M+(79Br) -
H2O]. HRMS: calcd for C14H11Br2F3O3 441.90273, found
441.90279.
2,3-Dib r om o-5-[4(e)-for m ylcycloh ex-(e)-yl]-6-(t r iflu o-
r om eth yl)-1,4-d ih yd r oxyben zen e (32b). 28b was hydro-
genated in the same manner as described for 28a to yield 32b
in quantitative yield. Rf (TLC, dichloromethane/ether 50:1)
) 0.6. 1H NMR (250 MHz, CDCl3): δ 1.38 (qd, 2H), 1.76 (dq,
2H), 2.08 (br d, 2H), 2.34 (m, 3H), 3.01 (tt, 1H), 5.70 (s, 1H),
6.06 (s, 1H), 9.64 (s, 1H). 19F NMR (CDCl3): δ -52.5 (s).
EIMS: m/z (%) 444 (51) [M+(79Br)], 426 (36) [M+(79Br) - H2O].
HRMS: calcd for C14H13Br2F3O3 443.91838, found 443.91823.
Gen er a l P r oced u r e for Syn t h esis of t h e P or p h yr in
Qu in on es. Pyrrole (33), 4-methylbenzaldehyde (34), and one
of the cyclohexyl carbaldehydes bearing a (hydro)quinone
substituent (i.e. 29a , 29b, 30a , 30b, 31a /b, 32a , or 32b) were
mixed in an adequate volume of dry dichloromethane in the
ratio 4:3:1, so that the concentration of pyrrole and of both
aldehydes was 0.01 mol L-1. Argon was bubbled through the
solution for 20 min, and an adequate amount of trifluoroacetic
acid was added subsequently, so that the acid concentration
was also 0.01 mol L-1. During the reaction a slight stream of
argon was bubbled through the solution. The reaction mixture
changed its color from yellow to dark red. After 4 h 0.75 equiv
(referring to amount of pyrrole) of tetrachloro-1,4-benzo-
quinone (TCQ) was added all at once and stirring at rt was
continued for 18 h. The volume of the reaction mixture was
then reduced to 150-200 mL, and the solution was deacidified
with 50 mL of a 5% solution of sodium hydrogen carbonate.
The product was purified by filtration over a short and dry
column of silica gel and with repeated column chromatography.
The porphyrin quinone contained about 10% chlorins, which
were converted to the porphyrin via oxidation with DDQ as
described in the literature.33 Other impurities were separated
with HPLC. The product was crystallized from dichlo-
romethane/methanol or dichloromethane/hexane at -30 °C
and dried in vacuo for several days at 40-50 °C.
2-[4-F or m ylcycloh exyl]-5,6-d im et h oxy-3-m et h yl-1,4-
ben zoqu in on e (Cis/Tr a n s Mixtu r e 31a /b). Pyridinium
chlorochromate (PCC) (3.0 g, 16.6 mmol) was added to 1.8 g
(6.1 mmol) of 27a /b in 20 mL of dichloromethane, and the
solution was stirred for 2.5 h. After dilution with 20 mL of
ether, the reaction mixture was filtered over Florisil, the
solvent was evaporated, and the oily residue was dried in
1
vacuo. Yield: 1.4 g (75%). Cis/trans ratio: 1:1 (from H NMR
spectrum). For characterization of 31a and 31b, small amounts
of 27a and 27b were oxidized, respectively.
2-[4(a )-F or m ylcycloh ex-(e)-yl]-5,6-d im eth oxy-3-m eth -
yl-1,4-ben zoqu in on e (31a ). 27a (60 mg, 0.2 mmol) was
dissolved in 5 mL of dichloromethane, and 90 mg (0.4 mmol)
of PCC was added. After workup as described above, 50 mg
(85%) of the aldehyde was obtained as an orange oil. A pure
sample of the aldehyde for elemental analysis could not be
obtained, since attempted purification by chromatography or
by recrystallization from hexane yielded no analytically pure
product. Cis/trans ratio (from 1H NMR spectrum): 15:85. Rf
(TLC, toluene/acetone 10:1) ) 0.5. 1H NMR (250 MHz,
CDCl3): δ 1.50 (br d, 2H), 1.64 (tt, 2H), 1.84 (qd, 2H), 2.04 (s,
3H), 2.36 (br d, 2H), 2.51 (m, 1H), 2.80 (tt, 1H), 3.99 (s, 6H),
9.80 (s, 1H). EIMS: m/z (%) 292 (100) [M+], 264 (13) [M+
-
CO]. HRMS: calcd for C16H20O5 292.13108, found 292.13102.
2-[4(e)-F or m ylcycloh ex-(e)-yl]-5,6-d im eth oxy-3-m eth -
yl-1,4-ben zoqu in on e (31b). 27b was oxidized as described
for 27a yielding 47 mg (81.3%) of aldehyde as an orange oil. A
pure sample of the aldehyde for elemental analysis could not
be obtained, since attempted purification by chromatography
or by recrystallization from hexane yielded no analytically pure
product. However, the crude product was sufficiently pure for
the reaction in the next step. Cis/trans ratio (from 1H NMR
spectrum): 5:95. Rf (TLC, toluene/acetone 10:1) ) 0.5. 1H
NMR (250 MHz, CDCl3): δ 1.32 (qd, 2H), 1.58 (br d, 2H), 2.04
(s, 3H), 2.08 (m, 4H), 2.36 (tt, 1H), 2.66 (tt, 1H), 3.99 (s, 3H),
4.00 (s, 3H), 9.64 (s, 1H). EIMS: m/z (%) 292 (100) [M+], 263
(10) [M+ - CHO]. HRMS: calcd for C16H20O5 292.13108, found
292.13099.
2,3-Dib r om o-5-[4(a )-for m ylcycloh ex-(e)-yl]-6-(t r iflu o-
r om eth yl)-1,4-ben zoqu in on e (28a ). PCC (3.4 g, 15.7 mmol)
was added to 1.4 g (3.1 mmol) of 24a in 20 mL of dichlo-
romethane, and the solution was reacted for 2 h. After dilution
with 20 mL of ether, filtration over Florisil, and drying in
vacuo, 1.1 g (75%) of the aldehyde was obtained as a dark
yellow oil. A pure sample of the aldehyde for elemental
analysis could not be obtained, since attempted purification
by chromatography or by recrystallization from hexane yielded
no analytically pure product. Cis/trans ratio (from 1H NMR
spectrum): 9:1. Rf (TLC, dichloromethane/ether 50:1) ) 0.7.
1H NMR (250 MHz, CDCl3): δ 1.56 (m, 4H), 2.00 (qd, 2H),
2.36 (br d, 2H), 2.54 (m, 1H), 2.80 (tt, 1H), 9.80 (s, 1H). 19F
NMR (CDCl3): δ -57.2 (s). EIMS: m/z (%) 442 (43) [M+(79Br)],
424 (24) [M+(79Br) - H2O]. HRMS: calcd for C14H11Br2F3O3
441.90273, found 441.0279.
2,3-Dib r om o-5-[4(a )-for m ylcycloh ex-(e)-yl]-6-(t r iflu o-
r om eth yl)-1,4-d ih yd r oxyben zen e (32a ). 28a (1.1 g, 2.5
mmol) was dissolved in 25 mL of toluene, and 50 mg of
hydrogenation catalyst (Pd-C; 10% Pd) was added. After
cessation of hydrogen uptake, the catalyst was removed by
filtration through sodium sulfate. After evaporation of the
solvent and drying in vacuo the hydroquinone 32a was
obtained in quantitative yield as a colorless oil. A pure sample
of the aldehyde for elemental analysis could not be obtained,
since attempted purification by chromatography or by recrys-
5-[4(a)-(2,3,5-Tr im eth yl-1,4-ben zoqu in on -6-yl)cycloh ex-
(e)-yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or p h yr in (35a ).
Reaction of 0.7 g (2.68 mmol) of the aldehyde 29a , 0.97 g (8.06
mmol, 0.95 mL) of 4-methylbenzaldehyde with 0.72 g (10.74
mmol, 0.75 mL) of pyrrole, and 1.22 g (10.74 mmol, 0.83 mL)
of trifluoroacetic acid in 1.1 L dichloromethane, followed by
oxidation with 2.0 g (8.05 mmol) of TCQ, proceeded according
to the general procedure. Repetitive column chromatography
(dichloromethane) and oxidation of chlorins with 10 mg (0.044
mmol) of DDQ gave 35a , which was further purified with
preparative HPLC: column, 32 × 125 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/ethyl
acetate 99:1; tR ) 6.3 min; flow, 64 mL/min. Analytical
HPLC: column, 4 × 250 mm; stationary phase, Nucleosil 50,
5 µm; mobile phase, dichloromethane/water 99.88:0.12; tR )
6.1 min; flow rate, 1.5 mL/min. Yield: 250 mg (11.5%), mp
318-320 °C, Rf (TLC, dichloromethane) ) 0.7. 1H NMR (500
MHz, CDCl3): δ -2.65 (br s, 2H), 2.08 (s, 3H), 2.10 (m, 2H),
2.12 (s, 3H), 2.30 (s, 3H), 2.67 (s, 3H), 2.71 (s, 6H), 2.71 (m,
4H), 3.51 (m, 2H), 3.61 (tt, J ) 9.7, 7.2 Hz, 1H), 5.48 (tt, J )
11.0, 7.2 Hz, 1H), 7.54 (AA′BB′ signal, 2H), 7.56 (AA′BB′
signal, 4H), 8.08 (AA′BB′ signal, 2H), 8.11 (AA′BB′ signal, 4H),
8.82 (AB signal, J ) 4.8 Hz, 4H), 8.92 (d, J ) 5.0 Hz, 2H),
9.61 (d, J ) 5.0 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ 12.48,

8678 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
12.51, 21.50, 21.54, 27.17, 33.11, 34.52, 40.20, 119.50, 119.53,
126.12, 127.27, 127.49, 127.93 (br), 130.58 (br), 131.51 (br),
134.40, 134.50, 137.22, 137.25, 138.89, 139.69, 140.11, 140.29,
141.20, 148.53, 187.73, 188.01. UV (dichloromethane): λmax
(log ꢀ) 266 (4.51), 272 (4.51), 373 (4.36), 303 (4.16), 400 (sh)
(4.90), 419 (5.65), 486 (3.54), 517 (4.23), 553 (3.98), 594 (3.71),
649 (3.72) nm. EIMS: m/z (%) 812 (5) [M+ + 2H], 811 (13)
[M+ + H], 810 (21) [M+], 581 (14) [tris(4-methylphenylene)-
porphyrin+ + H], 580 (8) [tris(4-methylphenylene)porphyrin+].
HRMS: calcd for C56H50N4O2 810.39338, found 810.39301.
Anal. Calcd for C56H50N4O2: C, 82.93; H, 6.21; N, 6.90.
Found: C, 82.92; H, 6.18; N, 7.06.
275 (4.45), 302 (4.19), 371 (4.35), 400 (4.87), 418 (5.61), 485
(3.56), 517 (4.23), 552 (3.97), 593 (3.70), 649 (3.72) nm.
EIMS: m/z (%) 833 (1) [M+ + H], 832 (1) [M+], 581 (11) [tris(4-
methylphenylene)porphyrin+ + H], 580 (17) [tris(4-methyl-
phenylene)porphyrin+]. HRMS: calcd for C58H48N4O2
832.37773, found 832.37747. Anal. Calcd for C58H48N4O2‚
0.5H2O: C, 82.73; H, 5.87; N, 6.65. Found: C, 82.61; H, 5.89;
N, 6.70.
5-[4(e)-(2-Meth yl-1,4-n a p h th oqu in on -3-yl)cycloh ex-(e)-
yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or p h yr in (36b). 36b
was synthesized using the same reaction scale as described
for 36a using aldehyde 30b instead of 30a and was further
purified with preparative HPLC: column, 32 × 125 mm;
stationary phase, Nucleosil 50, 5 µm; mobile phase, dichlo-
romethane/hexane 2:1; tR ) 4.8 min; flow rate, 64 mL/min.
Analytical HPLC: column, 4 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/hexane 7:3;
tR ) 8.0 min; flow, 1.5 mL/min. Yield: 202 mg (9.7%), mp
>350 °C, Rf (TLC, dichloromethane) ) 0.7. 1H NMR (500
MHz, CDCl3): δ -2.60 (s, 2H), 2.16 (br d, J ) 13.0 Hz, 2H),
2.52 (s, 3H), 2.66 (s, 3H), 2.70 (s, 6H), 2.89 (m, 4H), 3.30 (qd,
J ) 12.6, 3.2 Hz, 2H), 3.58 (tt, J ) 12, 3 Hz, 1H), 5.44 (tt, J )
12.5, 3.3 Hz, 1H), 7.54 (AA′BB′ signal, 2H), 7.56 (AA′BB′
signal, 4H), 7.72 (td, J ) 7.5, J ) 2.0 Hz, 1H), 7.76 (td, J )
7.2, 2.0 Hz, 1H), 8.06 (AA′BB′ signal, 2H), 8.10 (AA′BB′ signal,
4H), 8.14 (dd, J ) 7.2, 2.0 Hz, 1H), 8.18 (dd, J ) 7.5, 2.0 Hz,
1H) 8.79 (AB signal, J ) 4.8 Hz, 4H), 8.94 (d, J ) 4.8 Hz, 2H),
9.74 (d, J ) 4.8 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ 12.95,
21.51, 21.56, 31.81, 38.85, 41.07, 46.10, 119.58, 124.32, 126.16,
126.28, 127.27, 127.50, 130.59 (br), 131.37 (br), 131.78, 132.80,
133.28, 133.54, 134.41, 134.51, 137.24, 137.27, 138.77, 139.67,
143.59, 150.25, 185.43, 185.59. UV (dichloromethane): λmax
(log ꢀ) 244 (4.46), 249 (4.46), 268 (sh) (4.45), 275 (4.46), 303
(4.19), 371 (4.36), 400 (4.90), 418 (5.63), 485 (3.55), 516 (4.23),
552 (3.97), 593 (3.70), 648 (3.72) nm. EIMS: m/z (%) 833 (5)
[M+ + H], 832 (7) [M+], 581 (45) [tris(4-methylphenylene)-
porphyrin+ + H], 580 (21) [tris(4-methylphenylene)porphy-
rin+]. HRMS: calcd for C58H48N4O2 832.37773, found 832.37707.
Anal. Calcd for C58H48N4O2: C, 83.63; H, 5.81; N, 6.73.
Found: C, 83.61; H, 5.81; N, 6.75.
5-[4-(2,3-Dim eth oxy-5-m eth yl-1,4-ben zoqu in on -6-yl)cy-
cloh exyl]-10,15,20-tr is(4-m eth ylph en ylen e)por ph yr in (Cis/
Tr a n s Mixtu r e 37a /b). Reaction of 1.35 g (4.6 mmol) of the
1:1 cis/trans mixture of aldehydes 31a /b, 1.66 g (13.9 mmol,
1.63 mL) of 4-methylbenzaldehyde with 1.23 g (18.5 mmol, 1.28
mL) of pyrrole, and 2.1 g (18.5 mmol, 1.42 mL) of trifluoroacetic
acid in 1800 mL of dichloromethane followed by oxidation with
3.4 g (13.9 mmol) of TCQ proceeded according to the general
procedure. Repetitive column chromatography (dichloro-
methane/2-propanol 100:1) and oxidation of chlorins with 10
mg (0.044 mmol) of DDQ gave a 2:3 cis/trans mixture (from
1H NMR spectrum) of the porphyrin quinones 37a and 37b.
Separation of the diasterereomers was carried out with
preparative HPLC: column, 16 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/water
99.92:0.08; tR ) 6.5 min (37a ); tR ) 7.5 min (37b); flow rate,
16 mL/min. Analytical HPLC: column, 4 × 250 mm; station-
ary phase, Nucleosil 50, 5 µm; mobile phase, dichloromethane/
water 99.88:0.12; tR ) 4.9 min (37a ); tR ) 5.4 min (37b); flow
rate, 1.0 mL/min.
5-[4(e)-(2,3,5-Tr im eth yl-1,4-ben zoqu in on -6-yl)cycloh ex-
(e)-yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or p h yr in (35b).
Reaction of 0.68 g (2.61 mmol) of the aldehyde 29b, 0.94 g (7.83
mmol, 0.92 mL) of 4-methylbenzaldehyde with 0.70 g (10.45
mmol, 0.73 mL) of pyrrole, and 1.2 g (10.45 mmol, 0.80 mL) of
trifluoroacetic acid in 1050 mL of dichloromethane, followed
by oxidation with 1.93 g (7.83 mmol) of TCQ, proceeded
according to the general procedure. Repetitive column chro-
matography (dichloromethane) and oxidation of chlorins with
10 mg (0.044 mmol) of DDQ gave 35b, which was further
purified with preparative HPLC: column, 32 × 125 mm;
stationary phase, Nucleosil 50, 5 µm; mobile phase, dichlo-
romethane/ethyl acetate 99:1; tR ) 6.3 min; flow, 64 mL/min.
Analytical HPLC: column, 4 × 250 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/water
99.88:0.12; tR ) 7.0 min; flow rate, 1.5 mL/min. Yield: 280
mg (13.2%), mp >350 °C, Rf (TLC, dichloromethane) ) 0.7.
1H NMR (500 MHz, CDCl3): δ -2.63 (s, 2H), 2.08 (s, 3H), 2.10
(br d, 2H), 2.13 (s, 3H), 2.38 (s, 3H), 2.68 (s, 3H), 2.71 (s, 6H),
2.73 (qd, J ) 12.7, 3.3 Hz, 2H), 2.89 (br d, J ) 13.6 Hz, 2H),
3.25 (qd, J ) 12.9, 3.2 Hz, 2H), 3.47 (tt, J ) 12.0, 3.0 Hz, 1H),
5.39 (tt, J ) 12.5, 3.2 Hz, 1H), 7.53 (AA′BB′ signal, 2H), 7.55
(AA′BB′ signal, 4H), 8.06 (AA′BB′ signal, 2H), 8.08 (AA′BB′
signal, 4H), 8.78 (AB signal, J ) 5.0 Hz, 4H), 8.92 (d, J ) 5.0
Hz, 2H), 9.70 (d, J ) 5.0 Hz, 2H). 13C NMR (125 MHz,
CDCl3): δ 12.40, 12.48, 21.51, 21.56, 31.99, 38.89, 40.41, 46.17,
119.55, 119.58, 124.39, 127.28, 127.51, 130.56 (br), 131.39 (br),
134.42, 134.52, 137.25, 137.28, 138.83, 139.72, 140.00, 140.54,
141.20, 147.31, 187.94, 187.98. UV (dichloromethane): λmax
(log ꢀ) 266 (4.28), 272 (4.27), 307 (3.97), 372 (sh) (4.23), 400
(sh) (4.77), 419 (5.51), 485 (sh) (3.41), 517 (4.10), 552 (3.84),
593 (3.57), 649 (3.58) nm. EIMS: m/z (%) 812 (13) [M+ + 2H],
811 (37) [M+ + H], 810 (58) [M+], 581 (71) [tris(4-methylphen-
ylene)-porphyrin+ + H], 580 (12) [tris(4-methylphenylene)-
porphyrin+]. HRMS: calcd for C56H50N4O2 810.39338, found
810.39317. Anal. Calcd for C56H50N4O2: C, 82.93; H, 6.21;
N, 6.90. Found: C, 82.97; H, 6.35; N, 6.68.
5-[4(a )-(2-Meth yl-1,4-n a p h th oqu in on -3-yl)cycloh ex-(e)-
yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or p h yr in (36a ). Re-
action of 0.7 g (2.5 mmol) of the aldehyde 30a , 0.90 g (7.5 mmol,
0.88 mL) of 4-methylbenzaldehyde with 0.67 g (10.0 mmol, 0.69
mL) of pyrrole, and 1.14 g (10.0 mmol, 0.77 mL) of trifluoro-
acetic acid in 1000 mL of dichloromethane, followed by
oxidation with 1.85 g (7.5 mmol) of TCQ, proceeded according
to the general procedure. Repetitive column chromatography
(dichloromethane) and oxidation of chlorins with 10 mg (0.044
mmol) of DDQ gave 36a , which was further purified with
preparative HPLC: column, 32 × 125 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/hexane 2:1;
tR ) 4.0 min; flow: 64 mL/min. Analytical HPLC: column, 4
× 250 mm; stationary phase, Nucleosil 50, 5 µm; mobile phase,
dichloromethane/hexane 7:3; tR ) 10.2 min; flow rate, 1.5 mL/
min. Yield: 113 mg (5.4%), mp 320-322 °C, Rf (TLC,
dichloromethane) ) 0.7. 1H NMR (500 MHz, CDCl3): δ -2.66
(s, 2H), 2.20 (m, 2H), 2.48 (s, 3H), 2.66 (s, 3H), 2.70 (s, 6H),
2.78 (m, 4H), 3.54 (m, 2H), 3.76 (tt, 1H), 5.52 (tt, 1H), 7.54
(AA′BB′ signal, 2H), 7.56 (AA′BB′ signal, 4H), 7.74 (m, 2H),
8.06 (AA′BB′ signal, 2H), 8.10 (AA′BB′ signal, 4H), 8.14 (m,
1H), 8.22 (m, 1H), 8.80 (AB signal, J ) 4.8 Hz, 4H), 8.93 (d, J
) 5.0 Hz, 2H), 9.68 (d, J ) 5.0 Hz, 2H). 13C NMR (125 MHz,
CDCl3): δ 13.11, 21.52, 21.57, 27.06, 33.69, 34.52, 40.16,
119.54, 126.09, 126.21, 126.35, 127.28, 127.49, 131.33 (br),
131.89, 132.82, 133.33, 133.54, 134.41, 134.51, 137.26, 138.86,
139.65, 143.35, 151.51, 185.23, 185.65. UV (dichloro-
methane): λmax (log ꢀ) 244 (4.46), 249 (4.46), 269 (sh) (4.44),
5-[4(a )-(2,3-Dim et h oxy-5-m et h yl-1,4-b en zoq u in on -6-
yl)cycloh ex-(e)-yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or -
p h yr in (37a ). Yield: 140 mg (7.2%), mp 315-317 °C, Rf (TLC,
dichloromethane/2-propanol 99:1) ) 0.4. 1H NMR (500 MHz,
CDCl3): δ -2.65 (s, 2H, NH), 2.10 (m, 2H, He-3, He-5), 2.31 (s,
3H, quinone-3-CH3), 2.66 (m, 2H, Ha-3, Ha-5), 2.68 (s, 3H, 15-
p-phenyl-CH3), 2.71 (m, 2H, He-2, He-6), 2.71 (s, 6H, 10- and
20-p-phenyl-CH3), 3.50 (m, 2H, Ha-2, Ha-6), 3.61 (tt, J 1 ) 9.6
Hz, J 2 ) 7.2 Hz, 1H, Ha-4), 4.06 (s, 3H, CH3O), 4.12 (s, 3H,
CH3O), 5.47 (tt, J 1 ) 11.0 Hz, J 2 ) 7.2 Hz, 1H, Ha-1), 7.54
(AA′BB′, 2H, m-H 15-p-phenyl-CH3), 7.55 (AA′BB′, 4H, m-H
10- and 20-p-phenyl-CH3), 8.07 (AA′BB′, 2H, o-H 15-p-phenyl-
CH3), 8.08 (AA′BB′, 4H, o-H 10- and 20-p-phenyl-CH3), 8.80
(AB, J AB ) 4.7 Hz, 4H, porphyrin-H-12,13,17,18), 8.92 (d, J )
4.8 Hz, 2H, porphyrin-H-2,8), 9.61 (d, J ) 4.8 Hz, 2H,
porphyrin-H-3,7). 13C NMR (CDCl3): δ 12.25, 21.45, 27.08,
32.98, 34.34, 40.12, 61.10, 61.18, 119.46, 125.85, 127.19,

Cyclohexylene-Bridged Porphyrin Quinones
J . Org. Chem., Vol. 62, No. 25, 1997 8679
127.40, 127.80 (br), 130.48 (br), 131.21 (br), 134.33, 134.42,
137.18, 138.87, 139.64, 143.74, 144.46, 146.98, 184.44, 184.79.
UV (dichloromethane): λmax (log ꢀ) 284 (4.44), 368 (sh) (4.33),
400 (sh) (4.88), 419 (5.64), 486 (3.55), 518 (4.22), 553 (3.96),
594 (3.69), 650 (3.70) nm. EIMS: m/z (%) 844 (17) [M+ + 2H],
843 (23) [M+ + H], 842 (33) [M+], 581 (9) [tris(4-methylphen-
ylene)porphyrin+ + H], 580 (16) [tris(4-methylphenylene)por-
phyrin+]. HRMS: calcd for C56H50N4O4 842.38321, found
842.38302. Anal. Calcd for C56H50N4O4: C, 79.78; H, 5.98;
N, 6.64. Found: C, 79.45; H, 5.98; N, 6.49.
C54H41Br2F3N4O2: C, 65.20; H, 4.15; N, 5.63. Found: C, 65.35;
H, 4.20; N, 5.43.
5-[4(e )-(2,3-Dib r om o-5-(t r iflu or om e t h yl)-1,4-b e n zo-
q u in o n -6-y l)c y c lo h e x -(e )-y l]-10,15,20-t r is (4-m e t h y l-
p h en ylen e)p or p h yr in (38b). Reaction of 1.10 g (2.45 mmol)
of the 5:95 cis/trans mixture of aldehydes 32a /b, 0.88 g (7.35
mmol, 0.86 mL) of 4-methylbenzaldehyde with 0.66 g (9.8
mmol, 0.67 mL) of pyrrole, and 1.11 g (9.8 mmol, 0.76 mL) of
trifluoroacetic acid in 1000 mL of dichloromethane followed
by oxidation with 2.4 g (9.8 mmol) of TCQ proceeded according
to the general procedure. Repetitive column chromatography
(trichloromethane) and oxidation of chlorins with 10 mg (0.044
mmol) of DDQ gave the isomerically pure porphyrin quinone
38b (from 1H NMR spectrum), which was further purified by
preparative HPLC: column, 32 × 125 mm; stationary phase,
Nucleosil 50, 5 µm; mobile phase, dichloromethane/hexane 3:2;
tR ) 9.8 min; flow rate, 64 mL/min. Analytical HPLC: column,
4 × 250 mm; stationary phase, Nucleosil 50, 5 µm; mobile
phase, dichloromethane/hexane 1:1; tR ) 8.4 min; flow rate,
1.5 mL/min. Yield: 224 mg (9.2%), mp >350 °C, Rf (TLC,
trichloromethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ -2.63
(s, 2H), 2.23 (br d, J ) 12.6 Hz, 2H), 2.68 (s, 3H), 2.72 (s, 6H),
2.78 (qd, J ) 12.7 Hz, 3.2 Hz, 2H), 2.93 (br d, J ) 13.6 Hz,
2H), 3.28 (qd, J ) 12.5, 3.3 Hz, 2H), 3.78 (tt, J ) 12,0, 3.2 Hz,
1H), 5.41 (tt, J ) 12.5, 3.2 Hz, 1H), 7.54 (AA′BB′ signal, 2H),
7.56 (AA′BB′ signal, 4H), 8.06 (AA′BB′ signal, 2H), 8.08
(AA′BB′ signal, 4H), 8.80 (AB signal, J ) 4.9 Hz, 4H), 8.93 (d,
J ) 4.9 Hz, 2H), 9.65 (d, J ) 4.9 Hz, 2H). 13C NMR (125 MHz,
CDCl3): δ 21.51, 21.55, 32.40, 38.16, 42.32, 45.62), 119.70,
119.77, 120.66, 121.77 (q, J C-F ) 278 Hz), 122.88, 123.28,
127.29, 127.52, 130.66 (br), 131.42 (br), 132.16, 132.28 (q, J C-F
) 30 Hz), 132.39, 134.41, 134.52, 137.29, 137.34, 138.76,
139.52, 139.54, 139.63, 139.68, 155.61, 173.43, 177.26. 19F
NMR (CDCl3): δ -55.1 (s). UV (dichloromethane): λmax (log
ꢀ) 255 (sh) (4.27), 283 (4.32), 374 (4.36), 399 (sh) (4.88), 418
(5.63), 485 (sh) (3.54), 517 (4.22), 552 (3.94), 593 (3.70), 649
(3.69) nm. EIMS: m/z (%) 992 (1) [M+(79Br)], 581 (2) [tris(4-
methylphenylene)porphyrin+ + H], 580 (1) [tris(4-methylphen-
ylene)porphyrin+]. HRMS: calcd for C54H41Br2F3N4O2
992.15486, found 992.15421. Anal. Calcd for C54H41Br2-
F3N4O2: C, 65.20; H, 4.15; N, 5.63. Found: C, 65.07; H, 4.20;
N, 5.45.
Gen er a l P r oced u r e for t h e P r ep a r a t ion of t h e Zin c
P or p h yr in Qu in on es. The zinc porphyrin quinones Zn -35a ,
Zn -35b, Zn -36a , Zn -36b, Zn -37a , and Zn -37b were prepared
using the acetate method:20,34 25-50 mg of the porphyrin
quinone was dissolved in 10-30 mL of dichloromethane and
5 mL of a saturated solution of zinc(II) acetate in methanol
were added. After the insertion of zinc was complete (3-4 h,
check with UV/vis spectroscopy), the organic phase was
extracted three times with brine, dried over sodium sulfate,
and filtered. The zinc porphyrin quinones were crystallized
from dichloromethane/hexane or dichloromethane/methanol at
-30 °C and dried in vacuo for several days at 40-50 °C.
{5-[4(a)-(2,3,5-Tr im eth yl-1,4-ben zoqu in on -6-yl)cycloh ex-
(e)-yl]-10,15,20-t r is(4-m et h ylp h en ylen e)p or p h yr in a t o}-
zin c(II) (Zn -35a ). Zinc was inserted in 30 mg (0.037 mmol)
of 35a following the general procedure, and the product was
crystallized from dichloromethane/methanol. Yield: 30 mg
(92%), mp >350 °C. 1H NMR (500 MHz, CDCl3): δ 2.09 (s,
3H), 2.12 (m, 2H), 2.13 (s, 3H), 2.35 (s, 3H), 2.69 (s, 3H), 2.72
(m, 4H), 2.74 (s, 6H), 3.58 (m, 2H), 3.65 (tt, 1H), 5.62 (tt, J )
11.0, J ) 7.2 Hz, 1H), 7.53 (AA′BB′ signal, 2H), 7.56 (AA′BB′
signal, 4H), 8.07 (AA′BB′ signal, 2H), 8.09 (AA′BB′ signal, 4H),
8.91 (AB signal, J ) 5.0 Hz, 4H), 9.05 (d, J ) 5.0 Hz, 2H),
9.77 (d, J ) 5.0 Hz, 2H). UV (dichloromethane): λmax (log ꢀ)
265 (4.37), 273 (4.37), 305 (4.16), 349 (3.98), 400 (4.54), 421
(5.65), 515 (sh) (3.44), 552 (4.22), 594 (3.73) nm. EIMS: m/z
(%) 872 (100) [M+(64Zn)], 642 (43) [tris(4-methylphenylene)zinc
porphyrin+]. HRMS: calcd for C56H48N4O2Zn 872.30687, found
872.30635. Anal. Calcd for C56H48N4O2Zn: C, 76.92; H, 5.53;
N, 6.40. Found: C, 76.78; H, 5.59; N, 6.23.
5-[4(e)-(2,3-Dim et h oxy-5-m et h yl-1,4-b en zoq u in on -6-
yl)cycloh ex-(e)-yl]-10,15,20-tr is(4-m eth ylp h en ylen e)p or -
p h yr in (37b). Yield: 170 mg (8.7%), mp >350 °C, Rf (TLC,
dichloromethane/2-propanol 99:1) ) 0.4. 1H NMR (500 MHz,
2
CDCl3): δ -2.65 (s, 2H, NH), 2.10 (br d, J 3a3e ) 13.5 Hz, 2H,
He-3, He-5), 2.34 (s, 3H, quinone-3-CH3), 2.68 (s, 3H, 15-p-
phenyl-CH3), 2.72 (s, 6H, 10- and 20-p-phenyl-CH3), 2.72 (qd,
2
2H, Ha-3, Ha-5), 2.88 (br d, J 2a2e ) 13.6 Hz, 2H, He-2, He-6),
2
3.24 (qd, J 2a2e ≈ J 1a2a ≈ J 2a3a ≈ 12.8 Hz, J 2a3e ) 3.4 Hz, 2H,
Ha-2, Ha-6), 3.44 (tt, J 3a4a ) J 4a5a ) 12.0 Hz, J 3e4a ) J 4a5e ≈ 3
Hz, 1H, Ha-4), 4.06 (s, 3H, CH3O), 4.12 (s, 3H, CH3O), 5.38
(tt, J 1a2a ) J 1a6a ) 12.5 Hz, J 1a2e ) J 1a6e ) 3.4 Hz, 1H, Ha-1),
7.53 (AA′BB′, 2H, m-H 15-p-phenyl-CH3), 7.55 (AA′BB′, 4H,
m-H 10- and 20-p-phenyl-CH3), 8.06 (AA′BB′, 2H, o-H 15-p-
phenyl-CH3), 8.08 (AA′BB′, 4H, o-H 10- and 20-p-phenyl-CH3),
8.80 (AB, J AB ) 4.8 Hz, 4H, porphyrin-H-12,13,17,18), 8.92
(d, J ) 4.8 Hz, 2H, porphyrin-H-2,8), 9.70 (d, J ) 4.8 Hz, 2H,
porphyrin-H-3,7). 13C NMR (125 MHz, CDCl3): δ 12.28, 21.50,
21.55, 31.87, 38.77, 40.21, 46.07, 61.18, 61.28, 119.59, 124.21,
127.27, 127.50, 130.55 (br), 131.88 (br), 134.41, 134.50, 137.24,
137.27, 138.79, 139.20, 143.74, 144.46, 145.76, 184.60, 184.85.
UV (dichloromethane): λmax (log ꢀ) 283 (4.43), 368 (sh) (4.33),
400 (sh) (4.88), 419 (5.62), 485 (sh) (3.54), 517 (4.22), 552 (3.95),
593 (3.68), 649 (3.69) nm. EIMS: m/z (%) 844 (67) [M+ + 2H],
843 (67) [M+ + H], 842 (97) [M+], 581 (65) [tris(4-methylphen-
ylene)-porphyrin+ + H], 580 (100) [tris(4-methylphenylene)-
porphyrin+]. HRMS: calcd for C56H50N4O4 842.38321, found
842.38369. Anal. Calcd for C56H50N4O4: C, 79.78; H, 5.98;
N, 6.64. Found: C, 79.50; H, 5.98; N, 6.36.
5-[4(a )-(2,3-Dib r om o-5-(t r iflu or om e t h yl)-1,4-b e n zo-
q u in o n -6-y l)c y c lo h e x -(e )-y l]-10,15,20-t r is (4-m e t h y l-
p h en ylen e)p or p h yr in (38a ). Reaction of 1.13 g (2.5 mmol)
of the 9:1 cis/trans mixture of aldehydes 32a /b , 0.90 g (7.5
mmol, 0.88 mL) of 4-methyl benzaldehyde with 0.67 g (10
mmol, 0.69 mL) of pyrrole, and 1.14 g (10.0 mmol, 0.77 mL) of
trifluoroacetic acid in 1000 mL of dichloromethane followed
by oxidation with 2.45 g (10.0 mmol) of TCQ proceeded
according to the general procedure. Repetitive column chro-
matography (trichloromethane) and oxidation of chlorins with
10 mg (0.044 mmol) of DDQ gave a 8:2 cis/trans mixture of
1
the porphyrin quinones 38a and 38b (from H NMR spectrum).
Separation of the diastereomers with preparative HPLC:
column, 32 × 125 mm; stationary phase, Nucleosil 50, 5 µm;
mobile phase, dichloromethane/hexane 3:2; tR ) 8.6 min (38a );
flow, 64 mL/min. Analytical HPLC: column, 4 × 250 mm;
stationary phase, Nucleosil 50, 5 µm; mobile phase, dichlo-
romethane/hexane 1:1; tR ) 10.5 min (38a ); flow rate, 1.5 mL/
min. Yield: 120 mg (4.8%), mp >350 °C, Rf (TLC, trichlo-
romethane) ) 0.5. 1H NMR (500 MHz, CDCl3): δ -2.63 (s,
2H), 2.20 (m, 2H), 2.69 (s, 3H), 2.72 (s, 6H), 2.73 (m, 4H), 3.54
(m, 2H), 3.92 (tt, J ) 9.6, 7.2 Hz, 1H), 5.49 (tt, J ) 11.0, 7.2
Hz, 1H), 7.54 (AA′BB′ signal, 2H), 7.55 (AA′BB′ signal, 4H),
8.07 (AA′BB′ signal, 2H), 8.08 (AA′BB′ signal, 4H), 8.81 (AB
signal, J ) 5.0 Hz, 4H), 8.94 (d, J ) 5.0 Hz, 2H), 9.57 (d, J )
5.0 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ 21.51, 21.55,
27.66, 33.82, 35.33, 39.50, 119.66, 119.73, 123.99 (q, J C-F
)
279 Hz), 125.16, 127.30, 127.51, 127.30, 127.51, 131.31 (br),
131.88 (q, J C-F ) 30 Hz), 132.00, 134.41, 134.51, 137.28,
137.32, 138.83, 139.60, 139.70, 139.77, 139.78, 156.27, 173.39,
177.10. 19F NMR (CDCl3):
δ -55.1 (s). UV (dichlo-
romethane): λmax (log ꢀ) 257 (sh) (4.27), 284 (4.31), 371 (4.36),
400 (sh) (4.89), 419 (5.63), 486 (3.55), 517 (4.22), 553 (3.95),
594 (3.70), 650 (3.67) nm. EIMS: m/z (%) 992 (1) [M+(79Br)],
581 (1) [tris(4-methylphenylene)-porphyrin+ + H], 580 (1)
{5-[4(e)-(2,3,5-Tr im eth yl-1,4-ben zoqu in on -6-yl)cycloh ex-
(e)-yl]-10,15,20-t r is(4-m et h ylp h en ylen e)p or p h yr in a t o}-
zin c(II) (Zn -35b). Zinc was inserted in 30 mg (0.03 mmol)
of 35b following the general procedure, and the product was
crystallized from dichloromethane/methanol. Yield: 31 mg
[tris(4-methylphenylene)porphyrin+]. HRMS: calcd for C54H41
-
Br2F3N4O2 992.15486, found 992.15469. Anal. Calcd for

8680 J . Org. Chem., Vol. 62, No. 25, 1997
Dieks et al.
(95%), mp 290 °C. 1H NMR (500 MHz, CDCl3): δ 2.08 (s, 3H),
2.11 (br d, 2H), 2.12 (s, 3H), 2.38 (s, 3H), 2.65 (s, 3H), 2.75 (s,
6H), 2.76 (qd, J ) 12.6, 3.6 Hz, 2H), 2.91 (br d, J ) 13.8 Hz,
2H), 3.35 (qd, J ) 13.2, 3.2 Hz, 2H), 3.49 (tt, J ) 12.3, 3.3 Hz,
1H), 5.55 (tt, J ) 12.5, 3.4 Hz, 1H), 7.53 (AA′BB′ signal, 2H),
7.56 (AA′BB′ signal, 4H), 8.07 (AA′BB′ signal, 2H), 8.09
(AA′BB′ signal, 4H), 8.91 (AB signal, J ) 4.8 Hz, 4H), 9.05 (d,
J ) 5.0 Hz, 2H), 9.90 (s (br), 2H). UV (dichloromethane): λmax
(log ꢀ) 265 (4.40), 273 (4.39), 304 (4.16), 348 (4.00), 400 (4.62),
420 (5.71), 515 (3.47), 550 (4.29), 588 (3.72) nm. EIMS: m/z
(%) 872 (100) [M+(64Zn)], 642 (30) [tris(4-methylphenylene)zinc
porphyrin+]. HRMS: calcd for C56H48N4O2Zn 872.30687, found
872.30610. Anal. Calcd for C56H48N4O2Zn‚0.5 CH3OH: C,
76.21; H, 5.66; N, 6.29. Found: C, 76.56; H, 5.58; N, 6.07.
{5-[4(a )-(2-Met h yl-1,4-n a p h t h oq u in on -3-yl)cycloh ex-
(e)-yl]-10,15,20-t r is(4-m et h ylp h en ylen e)p or p h yr in a t o}-
zin c(II) (Zn -36a ). Zinc was inserted in 25 mg (0.03 mmol) of
36a following the general procedure, and the product was
crystallized from dichloromethane/methanol. Yield: 24 mg
(91%), mp 320-322 °C. 1H NMR (500 MHz, CDCl3): δ 2.20
(m, 2H), 2.44 (s, 3H), 2.70 (s, 3H), 2.74 (s, 6H), 2.80 (m, 4H),
3.62 (m, 2H), 3.78 (tt, 1H), 5.64 (tt, 1H), 7.51 (AA′BB′ signal,
2H), 7.53 (AA′BB′ signal, 4H), 7.65 (td, J ) 7.5, 2.0 Hz, 1H),
7.69 (td, J ) 7.5, 2.0 Hz, 1H), 7.96 (dd, J ) 7.5, 2.0 Hz, 1H),
8.11 (AA′BB′ signal, 2H), 8.13 (AA′BB′ signal, 4H), 8.16 (dd,
J ) 7.5, 2.0 Hz, 1H), 8.94 (AB signal, J ) 5.0 Hz, 4H), 9.08 (d,
the product was crystallized from dichloromethane/methanol.
Yield: 24 mg (90%), mp 300 °C. 1H NMR (250 MHz, CDCl3):
δ 2.13 (br d, 2H), 2.35 (s, 3H), 2.65 (s, 3H), 2.75 (s, 6H), 2.75
(qd, 2H), 2.93 (br d, 2H), 3.35 (qd, 2H), 3.49 (tt, 1H), 3.95 (s,
3H), 4.00 (s, 3H), 5.51 (tt, 1H), 7.53 (AA′BB′ signal, 2H), 7.56
(AA′BB′ signal, 4H), 8.07 (AA′BB′ signal, 2H), 8.09 (AA′BB′
signal, 4H), 8.91 (AB signal, J AB ) 5 Hz, 4H), 9.05 (d, J ) 5
Hz, 2H), 9.85 (s (br), 2H). UV (dichloromethane): λmax (log ꢀ)
254 (sh) (4.22), 285 (4.41), 313 (sh) (4.13), 348 (3.99), 400 (sh)
(4.61), 420 (5.72), 507 (sh) (3.43), 550 (4.28), 589 (3.71) nm.
EIMS m/z (%) 904 (100) [M+(64Zn)], 642 (12) [tris(4-methyl-
phenylene)zinc porphyrin+]. HRMS: calcd for C56H48N4O4Zn
904.29670, found 904.29608. Anal. Calcd for C56H48N4O4Zn‚
0.5CH3OH: C, 73.57; H, 5.46; N, 6.07. Found: C, 73.87; H,
5.52; N, 5.81.
{5-[4(a )-(2,3-Dib r om o-5-(t r iflu or om et h yl)-1,4-b en zo-
q u in o n -6-y l)c y c lo h e x -(e )-y l]-10,15,20-t r is (4-m e t h y l-
p h en ylen e)p or p h yr in a to}zin c(II) (Zn -38a ). 38a (30 mg,
0.028 mmol) was added to a suspension of 130 mg (1.6 mmol)
of zinc oxide in 2.5 mL of ether and 1.5 mL of trichloromethane.
Two drops of trifluoroacetic acid were added, and complexation
was complete within 15 min. After dilution with 5 mL of
trichloromethane, filtration over a short column (silica gel 60),
crystallization from trichloromethane/hexane, and drying, 28
mg (88%) of the product was obtained, mp >350 °C. 1H NMR
(500 MHz, CDCl3): δ 2.21 (m, 2H), 2.69 (s, 3H), 2.72 (s, 6H),
2.74 (m, 4H), 3.60 (m, 2H), 3.97 (tt, J ) 9.6, 7.2 Hz, 1H), 5.61
(tt, J ) 11.0, 7.2 Hz, 1H), 7.54 (AA′BB′ signal, 2H), 7.56
(AA′BB′ signal, 4H), 8.07 (AA′BB′ signal, 2H), 8.09 (AA′BB′
signal, 4H), 8.91 (AB signal, J ) 4.8 Hz, 4H), 9.06 (d, J ) 5.0
Hz, 2H), 9.72 (d, J ) 5.0 Hz, 2H). 19F NMR (CDCl3): δ -55.3
(s). UV (dichloromethane): λmax (log ꢀ) 253 (4.28), 290 (4.32),
308 (sh) (4.26), 349 (4.06), 401 (sh) (4.65), 420 (5.75), 483 (sh)
(3.16), 515 (3.51), 550 (4.31), 589 (3.75) nm. EIMS: m/z (%)
1054 (1) [M+(79Br,64Zn)], 642 (2) [tris(4-methylphenylene)zinc
porphyrin+]. HRMS: calcd for C54H39Br2F3N4O2Zn 1054.06840,
found 1054.06820. Anal. Calcd for C54H39Br2F3N4O2Zn: C,
61.30; H, 3.72; N, 5.30. Found: C, 61.21; H, 3.82; N, 5.01.
J
) 5.0 Hz, 2H), 9.80 (d, J ) 5.0 Hz. 2H). UV (dichlo-
romethane): λmax (log ꢀ) 245 (sh) (4.46), 249 (4.47), 270 (sh)
(4.42), 277 (4.43), 307 (4.23), 345 (sh) (4.10), 400 (sh) (4.65),
420 (5.74), 510 (3.49), 550 (4.32), 589 (3.76) nm. EIMS: m/z
(%) 894 (17) [M+(64Zn)], 642 (85) [tris(4-methylphenylene)zinc
porphyrin+]. HRMS: calcd for C58H46N4O2Zn 894.29122, found
894.29110. Anal. Calcd for C58H46N4O2Zn‚CH3OH: C, 76.33;
H, 5.43; N, 6.03. Found: C, 76.56; H, 5.62; N, 5.76.
{5-[4(e)-(2-Met h yl-1,4-n a p h t h oq u in on -3-yl)cycloh ex-
(e)-yl]-10,15,20-t r is(4-m et h ylp h en ylen e)p or p h yr in a t o}-
zin c(II) (Zn -36b). Zinc was inserted in 25 mg (0.03 mmol)
of 36b following the general procedure, and the product was
crystallized from dichloromethane/methanol. Yield: 25 mg
(92%), mp 330-332 °C. 1H NMR (500 MHz, CDCl3): δ 2.19
(br d, J ) 13.0 Hz, 2H), 2.48 (s, 3H), 2.67 (s, 3H), 2.72 (s, 6H),
2.91 (m, 4H), 3.37 (qd, J ) 13.1, 3.4 Hz, 2H), 3.60 (tt, J )
13.0, 3.0 Hz, 1H), 5.58 (tt, J ) 12.5, 3.5 Hz, 1H), 7.53 (AA′BB′
signal, 2H), 7.56 (AA′BB′ signal, 4H), 7.70 (td, J ) 7.5, 2.5
Hz, 1H), 7.73 (td, J ) 7.5, 2.5 Hz, 1H), 8.04 (dd, J ) 7.5, 2.5
Hz, 1H), 8.08 (AA′BB′ signal, 2H), 8.10 (AA′BB′ signal, 4H),
8.18 (dd, J ) 7.5 2.0 Hz, 1H), 8.91 (AB signal, J ) 4.8 Hz,
4H), 9.06 (d, J ) 5.0 Hz, 2H), 9.91 (s (br), 2H). UV (dichlo-
romethane): λmax (log ꢀ) 245 (sh) (4.43), 249 (4.44), 271 (sh)
(4.40), 276 (4.44), 308 (4.20), 343 (sh) (4.07), 400 (sh) (4.61),
420 (5.71), 510 (sh) (3.46), 550 (4.29), 589 (3.72) nm. EIMS:
m/z (%) 894 (4) [M+(64Zn)], 642 (28) [tris(4-methylphenylene)-
zinc porphyrin+]. HRMS: calcd for C58H46N4O2Zn 894.29122,
found 894.29101. Anal. Calcd for C58H46N4O2Zn‚2CH3OH: C,
75.03; H, 5.67; N, 5.83. Found: C, 75.28; H, 5.34; N, 5.89.
{5-[4(a )-(2,3-Dim et h oxy-5-m et h yl-1,4-b en zoq u in on -6-
yl)cycloh e x-(e )-yl]-10,15,20-t r is(4-m e t h ylp h e n yle n e )-
p or p h yr in a to}zin c(II) (Zn -37a ). Zinc was inserted in 25 mg
(0.03 mmol) of 37a following the general procedure, and the
product was crystallized from dichloromethane/methanol.
Yield: 24 mg (90%), mp 310-312 °C. 1H NMR (250 MHz,
CDCl3): δ 2.12 (m, 2H), 2.32 (s, 3H), 2.69 (s, 3H), 2.72 (m,
4H), 2.74 (s, 6H), 3.54 (m, 3H), 4.02 (s, 3H), 4.08 (s, 3H), 5.58
(tt, 1H), 7.53 (AA′BB′ signal, 2H), 7.56 (AA′BB′ signal, 4 H),
8.07 (AA′BB′ signal, 2H), 8.09 (AA′BB′ signal, 4H), 8.90 (AB
signal, J ) 5 Hz, 4H), 9.05 (d, J ) 5.0 Hz, 2H), 9.76 (d, J )
5.0 Hz, 2H). UV (dichloromethane): λmax (log ꢀ) 255 (sh) (4.24),
286 (4.44), 313 (sh) (4.16), 350 (4.02), 420 (5.74), 510 (sh) (3.48),
550 (4.32), 589 (3.75) nm. EIMS: m/z (%) 904 (100) [M+(64Zn)],
642 (22) [tris(4-methylphenylene)zinc porphyrin+]. HRMS:
calcd for C56H48N4O4Zn 904.29670, found 904.29600. Anal.
Calcd for C56H48N4O4Zn‚CH3OH: C, 72.95; H, 5.59; N, 5.97.
Found: C, 73.11; H, 5.59; N, 5.82.
{5-[4(e)-(2,3-Dib r om o-5-(t r iflu or om et h yl)-1,4-b en zo-
q u in o n -6-y l)c y c lo h e x -(e )-y l]-10,15,20-t r is (4-m e t h y l-
p h en ylen e)p or p h yr in a to}zin c(II) (Zn -38b). Insertion of
zinc in 38b followed the same manner as described for 38a .
Yield: 29 mg (91%), mp >350 °C. 1H NMR (500 MHz,
CDCl3): δ 2.23 (br d, J ) 13.0 Hz, 2H), 2.68 (s, 3H), 2.71 (s,
6H), 2.81 (qd, J ) 12.5, 3.3 Hz, 2H), 2.93 (br d, J ) 14.0 Hz,
2H), 3.37 (qd, J ) 13.0, 3.4 Hz, 2H), 3.81 (tt, J ) 12.3, 3.2 Hz,
1H), 5.55 (tt, J ) 12.5, 3.3 Hz, 1H), 7.53 (AA′BB′ signal, 2H),
7.56 (AA′BB′ signal, 4H), 8.07 (AA′BB′ signal, 2H), 8.09
(AA′BB′ signal, 4H), 8.91 (AB signal, J ) 4.8 Hz, 4H), 9.06 (d,
J ) 5.0 Hz, 2H), 9.81 (s (br), 2H). 19F NMR (CDCl3): δ -55.1
(s). UV (dichloromethane): λmax (log ꢀ) 252 (4.27), 286 (4.31),
310 (sh) (4.23), 350 (4.05), 401 (sh) (4.64), 420 (5.74), 484 (sh)
(3.17), 514 (3.51), 550 (4.31), 589 (3.73) nm. EIMS: m/z (%)
1054 (1) [M+(79Br,64Zn)], 642 (2) [tris(4-methylphenylene)zinc
porphyrin+]. HRMS: calcd for C54H39Br2F3N4O2Zn 1054.06840,
found 1054.06846. Anal. Calcd for C54H39Br2F3N4O2Zn: C,
61.30; H, 3.72; N, 5.30. Found: C, 61.63; H, 3.80; N, 4.90.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft (SFB 337, Normal-
verfahren and Heisenberg stipend for M.O.S.), by the
Volkswagenstiftung and by the Fonds der Chemischen
Industrie.
Su p p or tin g In for m a tion Ava ila ble: Structures of 37a
obtained from MNDO (MOPAC 6.0) calculations and the 1H
NMR spectra (500 MHz, CDCl3) of 15a , 15b, 24a , 24b, 37a ,
and 37b (10 pages). This material is contained in libraries
on microfiche, immediately follows this article in the microfilm
version of this journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
{5-[4(e)-(2,3-Dim et h oxy-5-m et h yl-1,4-b en zoq u in on -6-
yl)cycloh e x-(e )-yl]-10,15,20-t r is(4-m e t h ylp h e n yle n e )-
p or p h yr in a to}zin c(II) (Zn -37b). Zinc was inserted in 25
mg (0.03 mmol) of 37b following the general procedure, and
J O970752K