Diastereoselective intramolecular [4 + 4] photocycloaddition reaction of N-(naphthylcarbonyl)anthracene-9-carboxamides: Temperature effects and reversal of diastereoselectivity

Article abstract of DOI:10.1039/b005142j

Intramolecular diastereoselective [4 + 4] photocycloadditions of acyclic imides 1a and 1b possessing anthracene and naphthalene moieties were carried out in the solid state and in solution. For la, novel reversal of diastereoselectivity was observed on ch

Full text of DOI:10.1039/b005142j

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Diastereoselective intramolecular [4 ؉ 4] photocycloaddition
reaction of N-(naphthylcarbonyl)anthracene-9-carboxamides:
temperature effects and reversal of diastereoselectivity
1
Shigeo Kohmoto,*a Hyuma Masu,a Chuya Tatsuno,a Keiki Kishikawa,a Makoto Yamamotoa
and Kentaro Yamaguchib
a Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33,
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
b Chemical Analysis Centre, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522,
Japan
Received (in Cambridge, UK) 27th June 2000, Accepted 1st November 2000
First published as an Advance Article on the web 5th December 2000
Intramolecular diastereoselective [4 ϩ 4] photocycloadditions of acyclic imides 1a and 1b possessing anthracene and
naphthalene moieties were carried out in the solid state and in solution. For 1a, novel reversal of diastereoselectivity
was observed on changing the reaction phase. The diastereomeric excess was changed from Ϫ60% de in the solid state
at 60 ЊC to 70% de in acetone at Ϫ78 ЊC. Almost 100% de was observed for the solid-state photocycloaddition of 1b.
The reactivity of 1a in the solid state was discussed based on its single crystal X-ray analysis.
Introduction
Control of stereoselectivity is currently a topic of great interest
in organic photochemistry. Asymmetric induction has been
carried out successfully in solid-state photochemistry of some
chiral crystals formed by spontaneous resolution of chiral
substrates on crystallisation.1 Diastereoselective reactions have
also been achieved in solid-state photochemistry using
covalently bound chiral auxiliaries2 or with noncovalent linkers
forming organic salts,3 which causes conformational biases
of the transition states. However, the reversal of diastereo-
selectivity starting from the same compound is rarely attained
in photochemical reactions by merely changing the reaction
conditions. However, there are numerous examples of this in
ground-state organic chemistry, especially in aldol conden-
sations.4 In order to obtain the other diastereomer as a photo-
product, the reaction should be carried out with the chiral
auxiliary possessing the opposite absolute configuration, as is
Fig. 1 ORTEP diagram of the molecular structure of 1a with thermal
ellipsoids drawn at the 50% probability level. The distances between two
usual in asymmetric synthesis. One promising exception was the
temperature dependent enantioselective photoisomerization of
cyclooctene in which the entropy term of the reaction was not
negligible, thus the enantioselectivity was inverted according to
the increase of the reaction temperature.5 In thermal reactions,
similar temperature dependent diastereofacial selectivity has
also been reported.6 A reversal of de was observed in the
addition reaction of butyllithium.7
As a continuation of our study on the photochemistry of
aromatic amides,8 we have examined the diastereoselective
intramolecular photocycloaddition of acyclic imides possessing
anthracene and naphthalene moieties as 4π reactants. Among
the photocycloadditions of aromatic compounds,9 the [4 ϩ 4]
and [4 ϩ 2] cycloadditions of anthracene10 and naphthalene
derivatives11 are well known reactions. Diastereoselective
[4 ϩ 4]12 and [4 ϩ 2]13 cycloadditions of anthracene derivatives
using chiral auxiliaries have been reported, intermolecularly
in the solid state and intramolecularly in solution, respectively.
In this paper, we report on temperature effects on the [4 ϩ 4]
photocycloaddition reaction of anthracene–naphthalene system
both in solution and in the solid state, and the reversal of the
diastereoselectivity.
reaction sites: C10–C21, 2.89 Å; C17–C28, 4.80 Å. The torsion angle,
C17–C10–C21–C28, 42.8Њ.
Results and discussion
In order to have efficient overlap of π-orbitals of two chromo-
phores, the anthracene and naphthalene moieties, we planned
to connect them with an iminodicarbonyl linkage, and thus
prepared acyclic imides 1a and 1b. The single crystal X-ray
structure of 1a possessing an N-(1S)-1-phenylethyl group as a
chiral auxiliary shows that the naphthalene and anthracene
rings face each other with a torsion angle (C17–C10–C21–C28)
of 42.8Њ and distances of 2.89 and 4.80 Å for C10–C21 and
C17–C28, respectively (Fig. 1). Due to the π–π interactions
between the two aromatic rings, these two rings are located
preferentially in positions in which they face each other.
Moreover, this orientation of the aromatic rings can also be
influenced by the nature of the iminodicarbonyl group which
may be considered to be a sequence of two amide functions.
Therefore, the two carbonyls tend to be located in nearly the
same plane in a W-shape due to electronic repulsion. Similar cis
favorable conformations were observed in N-methyl aromatic
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J. Chem. Soc., Perkin Trans. 1, 2000, 4464–4468
This journal is © The Royal Society of Chemistry 2000
DOI: 10.1039/b005142j

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amides and N,NЈ-dimethyl aromatic ureas.14 In contrast,
similar aromatics possessing amino,15 propylene,16 and ester17
linkages instead of an iminodicarbonyl were reported to lack
this tendency in their crystalline structures. In addition to
these, 1a has the following features. After the [4 ϩ 4] cyclo-
addition, the iminodicarbonyl linkage creates a five-membered
imido ring, a favorable ring formation in photocycloaddition
according to the Rule of Five.18 Carbonyl groups contribute to
the construction of networks which assist the formation of
the crystal structure owing to their C–H ؒ ؒ ؒ O interactions.19
Interatomic distances (between the two molecules) of 2.46
and 2.37 Å were observed for O1–H13 and O2–H12, respec-
tively, which indicated the existence of such interactions.
If the photocycloaddition proceeds stereoselectively from
this conformation (the conformation in the crystal structure
shown as conformation A in Scheme 1) 1a should afford the
Fig. 2 Temperature effect on the conversion and diastereoselectivity
of the solid-state photocycloaddition of 1a after 6 h irradiation.
Fig. 3 ORTEP diagram of the molecular structure of 2a with thermal
ellipsoids drawn at the 50% probability level.
version yields and the diastereoselectivity (% de) of the photo-
cycloaddition of 1a in the solid state at various reaction
temperatures. The diastereoselectivity was determined based on
the comparison of the integration of methyl groups after 6 h at
various reaction temperatures. Melting of the resulting reaction
mixture was not observed during or after the irradiation. Up
to 50% conversion (reaction temperature below 74 ЊC), the de
was in the range of 45–60%. With an increase of the reaction
temperature, the conversion yield increased. Complete con-
version was observed at 87 ЊC with 24% de.
Two diastereomeric cycloadducts were separated by HPLC
and their absolute configurations were determined to be 2a and
3a as the major and minor isomers, respectively by their single
crystal X-ray analyses. Their space groups belong to the chiral
space group P212121. Fig. 3 and 4 show the ORTEP diagrams of
the major and minor diastereomers 2a and 3a, respectively.
Their absolute configurations were deduced from the known
chiral centre, the attached (1S)-1-phenylethyl group. Their
configurations indicate that the photocycloaddition proceeds
predominantly from the conformation A as observed in the
X-ray structure of 1a. In spite of the existence of disorder
originating in the higher reaction temperature and the progress
of the reaction, moderate diastereoselectivity was observed
Scheme 1
[4 ϩ 4] cycloadduct 2a predominantly. Powdered single crystals
of 1a were sandwiched between two Pyrex cover glasses
wrapped with a polyethylene bag and irradiated for 6 h in
an ice–water bath. However, almost no reaction (conversion of
2% with 60% de) occurred at this temperature. The lack of
reactivity is probably due to the larger torsion angle between
the anthracene and the naphthalene rings and the long C10–
C21 distance (4.80 Å) which is longer than the distance limit
(4.2 Å) between two double bonds for photocycloaddition.20
These cause ineffective overlap between the π-orbitals. We
considered that the photocycloaddition might proceed at an
elevated temperature upon irradiation since the molecule
would be forced to vibrate in the crystal lattice and to locate two
π planes in suitable positions for the cycloaddition by reducing
the C10–C21 distance and the torsion angle between the
anthracene and the naphthalene rings. Fig. 2 shows the con-
1
after complete conversion. The H NMR spectrum of 2a was
almost identical to that of 3a except for the chemical shifts of
the methyl group of the 1-phenylethyl group (δMe 2a: 2.12, 3a:
2.16) and one of the aromatic protons which showed an up-field
shift of 0.15 ppm (δHa 2a: 6.37, δHb 3a: 6.52) compared to
that of 3a. This up-field shift could be interpreted in terms of
J. Chem. Soc., Perkin Trans. 1, 2000, 4464–4468
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Fig. 5 Arrhenius plots of the ratio of diastereomers (3a:2a) against
1/T.
Fig. 4 ORTEP diagram of the molecular structure of 3a with thermal
ellipsoids drawn at the 50% probability level.
the slightly stronger shielding effect caused by the phenyl group
of the 1-phenylethyl group of 2a than that of 3a on the facing
peri-position of aromatic proton Ha and Hb, respectively.
Recrystallisation of acyclic imide 1b with the bulkier chiral
auxiliary, 1-naphthylethyl group, gave powdery fine crystals
which were not appropriate for single crystal X-ray analysis. In
contrast to the solid-state photocycloaddition of 1a, the intra-
molecular [4 ϩ 4] photocycloaddition of 1b proceeded in the
solid state even at lower temperatures (ca. 15 ЊC) with almost
100% de within experimental error after complete conversion.
Since the cycloadduct did not afford a suitable single crystal for
X-ray diffraction analysis, the configurational determination of
1
[4 ϩ 4] cycloadduct was carried out based on H NMR study.
Unlike the solid-state photocycloaddition, two diastereomers
were obtained in the reaction of 1b in solution. Irradiation of a
toluene solution of 1b at 15 ЊC for 10 min gave a mixture of two
diastereomeric isomers in a 74:26 ratio in almost quantitative
yield. These two diastereomers were hard to separate by HPLC.
The major diastereomer was the same as obtained from the
solid-state photochemical reaction and its configuration was
deduced to be 3b from the following 1H NMR spectral
comparison. As mentioned above, the aromatic proton of 2a
(Ha) appears at higher field than that of 3a (Hb). A similar
shielding tendency should be observed in diastereomers 2b and
3b. Therefore, the diastereomer possessing the aromatic proton
(Ha) whose chemical shift was 0.27 ppm higher than the other
(Hb) was assigned as 2b (δHa: 5.98, δHb: 6.25). As for the methyl
protons, this was also consistent with the observations for those
of 2a and 3a. The methyl protons of 3b (δ 2.28) appeared at
slightly lower field than that of 2b (δ 2.25). The results indicate
that 1b has the conformation B in its solid state, which is
different from that of 1a.
In order to examine the selectivity of the cycloaddition in
different reaction phases, either in the solid state or in solution,
and also the temperature effect, the photocycloaddition of 1a
and 1b was examined in solution. Three solvents, acetone (47 to
Ϫ78 ЊC), chloroform (47 to Ϫ78 ЊC), and toluene (90 to
Ϫ78 ЊC) were employed at various reaction temperatures. The
irradiation was performed using a high-pressure mercury lamp
to afford [4 ϩ 4] cycloadducts with various diastereoisomeric
ratios in almost quantitative yields. The best diastereoselectivi-
ties were observed in acetone at Ϫ78 ЊC and were 70 and 86%
de for 1a and 1b affording 2b and 3b, respectively. In all solv-
ents, the 1-naphthylethyl derivative 1b resulted in a better
diastereoselectivity. At higher reaction temperature, the
decrease of diastereoselectivity was observed for both 1a and
1b in all three solvents. However, the reversal of diastereo-
selectivity, from 19% de at Ϫ78 ЊC to Ϫ4% de at 90 ЊC, was
observed for 1a in toluene. Except for 1a in toluene, the
cycloadducts derived from the conformation B were obtained
Fig. 6 Arrhenius plots of the ratio of diastereomers (3b:2b) against
1/T.
as the major diastereomers, in contrast to the solid-state
cycloaddition of 1a in which 2a was the major diastereomer.
Solvation of 1a with toluene via π–π stacking might affect
the conformation of the transition state. The diastereoselec-
tivity of the photocycloaddition can be explained by the steric
hindrance between the anthracene ring and the phenyl of the
1-phenylethyl group or the naphthyl of the 1-(1-naphthyl)ethyl
group in the conformation B. Arrhenius plots were carried out,
plotting the logarithm of the ratios of diastereomers (3a:2a or
3b:2b) against 1/T (Fig. 5 and Fig. 6). The differences in
activation energy (∆Ea) between the formation of two diastereo-
mers were 0.5, 0.4, and 0.1 kcal molϪ1 for 1a in acetone, chloro-
form, and toluene, respectively, and 0.4, 0.2, 0.2 kcal molϪ1 for
1b in acetone, chloroform, and toluene, respectively.
Since 1a and 1b contain two chromophores, it is conceivable
that the reaction involves an excited naphthyl or anthryl
moiety. Therefore, the effect of irradiation wavelength was
examined in solution. The UV spectra of 1a and 1b showed
absorptions at 380 (379) and 399 nm corresponding to the
anthryl group, which was missing in the related carboxamide
with two naphthyl moieties21 instead of one anthryl and one
naphthyl moieties. Thus, selective irradiation of the anthryl
moiety was carried out in benzene with a high-pressure Hg
lamp through the UV cut-off filter (Toshiba L-39: trans-
mittance 85 and 1% at 405 and 365 nm, respectively) at 0 ЊC.
Almost the same results were obtained as in the irradiation of
them with a Pyrex filter. Diastereoselectivities of (Ϫ8) 2%
de and 61 2% de were obtained independent of irradiation
wavelengths for the reactions of 1a and 1b, respectively.
Therefore, the photocycloadditions should involve the excited
anthryl moiety. The PM3 calculation of 1a showed that the
molecular orbital of its LUMO localised completely on the
anthryl moiety.
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J. Chem. Soc., Perkin Trans. 1, 2000, 4464–4468

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The present findings show the novel temperature effect on the
photocycloaddition in the solid state and the reversal of the
diastereoselectivity depending on the reaction phases.
5.14; N, 2.64%); λmax(CH3CN)/nm 262.5 (ε/dm3 molϪ1 cmϪ1 37
000), 283 (13 800), 295 (10 300), 327 (5500), 379 (4500) and 399
(3800); νmax(KBr)/cmϪ1 1650 (C=O); δH(400 MHz; CDCl3
Me4Si) 2.59 (3 H, br), 5.95 (1 H, br), 6.25 (1 H, br), 6.48 (1 H, d,
J 7.8), 6.58 (1 H, t, J 7.8), 6.68–6.67 (1 H, md, J 6.4), 6.96 (1 H,
t, J 7.2,), 7.07 (1 H, d, J 7.6), 8.11–7.15 (16 H, m) and 8.92 (1 H,
br); δC(125 MHz; CDCl3; Me4Si) 18.34 (q), 51.25 (d), 122.60
(d), 122.83 (d), 123.46 (d), 123.51 (d), 123.77 (d), 124.82 (d),
124.95 (d), 125.07 (d), 125.17 (d), 125.63 (d), 125.70 (d), 125.99
(d), 126.51 (d), 126.55 (s), 126.60 (d), 126.89 (d), 127.13 (d),
128.03 (s), 128.15 (d), 128.24 (d), 128.73 (d), 128.90 (d), 129.31
(d), 129.67 (s), 130.09 (s), 130.19 (s), 131.76 (s), 131.82 (s),
132.56 (s), 133.81 (s), 170.78 (s) and 173.82 (s); m/z (EI) 529
(Mϩ, 41%), 408 (6), 374 (98), 331 (37), 303 (17), 205 (49), 177
(80), 155 (99), 127 (100) and 57 (49).
Experimental
General
Mps were determined on a Yanaco MP-S3 apparatus and are
uncorrected. IR spectra were recorded on a Hitachi I-2000
spectrometer. 1H and 13C NMR spectra were recorded on JEOL
GSX-400 and GSX-500 spectrometers in CDCl3 with Me4Si as
an internal standard; J values are given in Hz. EI mass spectra
were measured with a Hitachi RMU-7M mass spectrometer.
Reaction mixtures were concentrated on a rotary evaporator
at 10–15 mmHg. Chromatographic separations were accom-
plished by flash column chromatography on silica gel (Fuji gel
BW 200; 150–350 mesh). Separation of diastereomers was
carried out by a preparative HPLC run; column Merck Si 60 (7
µm, 10 × 250 mm), hexane–ethyl acetate as eluent. Photo-
cycloaddition reactions were carried out using a USHIO 450 W
high-pressure mercury lamp. All solvents were freshly distilled
and stored over 4 Å molecular sieves.
Photocycloaddition of 1a and 1b
For preparative runs, a benzene solution (15 cm3) of 1a or 1b
(0.30 mmol) was irradiated through Pyrex glass filter for 20
min. The reaction was almost quantitative and the evaporation
of solvent gave the corresponding [4 ϩ 4] cycloadducts. Solid-
state photoreaction of 1a was carried out as follows. Carbox-
amide 1a (10.0 mg, 0.021 mmol) was sandwiched between two
Pyrex slide glasses which were placed in a polyethylene bag and
irradiated in a temperature controlled water bath ( 0.5 ЊC) for
6 h (3 h for each side). The ratio of diastereomer was determined
based on the comparison of integrals of methyl protons of both
Preparation of carboxamide 1
N-((1S)-1-Phenylethyl)-N-(1-naphthylcarbonyl)anthracene-9-
carboxamide 1a. To a solution of N-((1S)-1-phenylethyl)-
anthracene-9-carboxamide (0.400 g, 1.23 mmol; prepared from
(1S)-1-phenylethylamine and anthracene-9-carbonyl chloride)
in toluene (30 cm3) was added triethylamine (2.0 equiv.) at room
temperature. To the resulting solution was added dropwise
naphthalenecarbonyl chloride (0.37 cm3, 2.46 mmol). The
resulting mixture was heated at reflux for 15 h and then it
was quenched with saturated NaHCO3 (20 cm3) and washed
with 1 M hydrochloric acid (20 cm3) and brine (20 cm3). The
organic layer was dried (MgSO4) and concentrated in vacuo.
The product was recrystallised from n-hexane–ethyl acetate
to give yellow crystals of 1a (0.613 g, 65%); mp 195–196 ЊC
(from n-hexane–ethyl acetate) (Found: C, 84.89; H, 5.19; N,
2.92. C34H25NO2 requires C, 85.15; H, 5.25; N, 2.92%);
λmax(CH3CN)/nm 262.5 (ε/dm3 molϪ1 cmϪ1 41 100), 326 (6500),
380 (4800) and 399 (4500); νmax(KBr)/cmϪ1 1660 (C=O);
δH(400 MHz; CDCl3; Me4Si) 2.29 (3 H, br s, Me), 6.39 (1 H, br),
6.52–6.57 (2 H, m), 6.65 (1 H, td, J 8.0 and 1.0,), 6.86 (1 H, d,
J 8.0), 7.02 (2 H, t, J 7.1), 7.15–7.50 (12 H, m), 7.84 (1 H, d,
J 8.8) and 7.96 (2 H, br); δC (125 MHz; CDCl3; Me4Si) 17.86
(q), 55.68 (d), 123.02 (d), 123.24 (d), 124.96 (d), 125.35 (d),
125.42 (d), 126.15 (d), 126.86 (d), 127.10 (d), 127.97 (d), 128.11
(s), 128.18 (s), 128.31 (s), 128.36 (d), 128.42 (d), 129.10 (d),
129.31 (d), 130.06 (s), 130.33 (s), 132.14 (s), 133.11 (s), 171.36
(s) and 173.77 (s); m/z (EI) 479 (Mϩ, 46%), 374 (100), 331 (24),
303 (9), 205 (57), 177 (49), 155 (35) and 127 (32).
1
diastereomers in their H NMR spectra. For solution photo-
reaction, carboxamide 1a or 1b (1.25 × 10Ϫ2 M) in an appropri-
ate solvent was irradiated under bubbling of argon through
Pyrex filter for 20 min and the diastereomer ratio was deter-
mined by 1H NMR spectroscopy.
[4 ؉ 4] Cycloadduct 2a. Colorless crystals; mp 187–189 ЊC
(from n-hexane–ethyl acetate) (Found: C, 84.91; H, 5.19; N,
2.78. C34H25NO2 requires C, 85.15; H, 5.25; N, 2.92%); δH(400
MHz; CDCl3; Me4Si) 2.12 (3 H, d, J 7.3), 4.11 (1 H, ddd,
J 10.7, 7.3 and 1.5), 4.50 (1 H, d, J 10.7), 5.86–5.97 (2 H, m),
6.18 (1 H, dd, J 8.4 and 7.3), 6.37 (1 H, d, J 7.6), 6.69–7.24
(11 H, m), 7.38 (1 H, t, J 7.6), 7.45 (2 H, t, J 8.0) and 7.68
(2 H, d, J 7.5); δC(125 MHz; CDCl3; Me4Si) 16.75 (q), 48.01 (d),
50.85 (d), 53.02 (d), 63.31 (s), 66.89 (s), 124.16 (d), 124.39 (d),
125.44 (d), 125.59 (d), 125.79 (d), 126.11 (d), 126.48 (d), 126.56
(d), 127.02 (d), 127.17 (d), 127.32 (d), 127.57 (d), 128.11 (d),
128.59 (d), 134.05 (d), 137.83 (d), 139.23 (s), 139.77 (s), 140.92
(s), 141.14 (s), 143.02 (s), 143.06 (s), 143.75 (s), 176.44 (s) and
177.62 (s); m/z (EI) 479 (Mϩ, 42%), 374 (92), 331 (19), 303 (11),
205 (84), 177 (100), 155 (93), 127 (81), 105 (66), 77 (29).
Crystallographic data for 2a.† C34H25NO2, M = 479.58,
orthorhombic, space group P212121 (#19), a = 13.294(2),
b = 15.467(2), c = 12.047(1) Å, V = 2477.0(5) Å3, Z = 4,
Dcalc = 1.286
g
cmϪ3
,
T = 296.2 K, µ = 6.19 cmϪ1
Crystallographic data for 1a.† C34H25NO2, M = 479.58, ortho-
rhombic, space group P212121 (#19), a = 13.9906(9),
b = 22.060(1), c = 8.082(1) Å, V = 2494.2(4) Å3, Z = 4,
(CuKα = 1.5418Å), R = 0.088 (Rw = 0.089) for 1589 observed
reflections [I > 0.70σ(I)].
Dcalc = 1.277
g
cmϪ3
,
T = 296.2 K, µ = 6.23 cmϪ1
[4 ؉ 4] Cycloadduct 3a. Colorless crystals; mp 187–189 ЊC
(from n-hexane–ethyl acetate) (Found: C, 84.87; H, 5.21; N,
2.91. C34H25NO2 requires C, 85.15; H, 5.25; N, 2.92%);
(CuKα = 1.5418 Å), R = 0.040 (Rw = 0.038) for 1864 observed
reflections [I > 2.00σ(I)].
νmax(KBr)/cmϪ1 1700 (C᎐O); δ (400 MHz; CDCl ; Me Si) 2.16
᎐
H
3
4
N-((1S)-1-Naphthylethyl)-N-(1-naphthylcarbonyl)anthracene-
9-carboxamide 1b. In a similar manner as for the preparation of
1a, 1b was prepared from N-((1S)-1-naphthylethyl)anthracene-
9-carboxamide with naphthalenecarbonyl chloride as yellow
needles; mp 170–172 ЊC (from n-hexane–ethyl acetate) (Found:
C, 86.03; H, 5.02; N, 2.61. C38H27NO2 requires C, 86.18; H,
(3 H, d, J 7.3), 4.15 (1 H, ddd, J 10.8, 7.2 and 1.5), 4.53 (1 H, d,
J 11.0), 5.89 (2 H, dd, J 8.3 and 1.4), 5.93 (1 H, q, J 7.2), 6.20
(1 H, dd, J 8.4 and 7.3), 6.52 (1 H, d, J 7.8), 6.61–7.25 (11 H,
m), 7.38 (1 H, t, J 7.6), 7.46 (2 H, t, J 8.0), 7.70 (2 H, d, J 7.6);
δC(125 MHz; CDCl3; Me4Si) 17.13 (q), 48.07 (d), 51.30 (d),
53.09 (d), 63.41 (s), 66.87 (s), 124.24 (d), 124.45 (d), 125.45 (d),
125.64 (d), 125.80 (d), 126.17 (d), 126.53 (d), 127.06 (d), 127.25
(d), 127.32 (d), 127.35 (d), 127.42 (d), 128.03 (d), 128.70 (d),
134.09 (d), 137.80 (d), 139.49 (s), 139.84 (s), 140.95 (s), 141.20
† CCDC reference number 207/496. See http://www.rsc.org/suppdata/
p1/b0/b005142j/ for crystallographic files in .cif format.
J. Chem. Soc., Perkin Trans. 1, 2000, 4464–4468
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m/z (EI) 479 (Mϩ, 41%), 374 (100), 331 (27), 303 (11), 205 (66),
177 (53), 155 (44), 127 (37), 105 (43), 77 (16).
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6 G. Cainelli, D. Giacomini and P. Galletti, Chem. Commun., 1999,
567.
7 G. Cainelli, G. Giacomini and M. Walzl, Angew. Chem., Int. Ed.
Engl., 1995, 34, 2150.
Crystallographic data for 3a.† C34H25NO2, M = 479.58,
orthorhombic, space group P212121 (#19), a = 12.384(2),
b = 21.405(2), c = 9.292(2) Å, V = 2463.2(6) Å3, Z = 4,
Dcalc = 1.293
g
cmϪ3
,
T = 296.2 K, µ = 6.27 cmϪ1
(CuKα = 1.5418Å), R = 0.039 (Rw = 0.040) for 1589 observed
reflections [I > 3.00σ(I)].
[4 ؉ 4] Cycloadduct 2b. Characteristic peaks assigned for
the minor diastereomer 2b from the 1H NMR spectrum of
the mixture of 2b and 3b (together with those of major 3b for
comparison); δH(500 MHz; CDCl3; Me4Si) Me; 2.25 (d, J 7.3,
2b), 2.28 (d, J 7.3, 3b); CH; 4.07 (ddd, J 10.7, 7.1, 1.2, 2b), 4.10
(ddd, J 10.9, 7.2 and 1.0, 3b); CH; 4.46 (2b),* 4.49 (d, J 10.9,
8 S. Kohmoto, T. Kobayashi, T. Nishio, I. Iida, K. Kishikawa,
M. Yamamoto and K. Yamada, J. Chem. Soc., Perkin Trans. 1, 1996,
529; K. Kishikawa, S. Akimoto, S. Kohmoto, M. Yamamoto and
K. Yamada, J. Chem. Soc., Perkin Trans. 1, 1997, 77.
3b); CH᎐CH; 5.88 (dd, J 8.5 and 1.2, 2b), 5.81 (dd, J 8.5 and
᎐
1.2, 3b); CH᎐CH; 6.15 (2b),* 6.14 (dd, J 8.5 and 7.2, 3b) (*due
᎐
9 J. J. McCullough, Chem. Rev., 1987, 87, 811.
to the overlap of peaks, coupling constants were difficult to
determine).
10 D. E. Applequist, M. A. Lintner and R. Searle, J. Org. Chem., 1968,
33, 254; H. Bouas-Laurent, A. Castellan and J.-P. Desvergne, Pure
Appl. Chem., 1980, 52, 2633; H.-D. Becker, V. Langer and
H.-C. Becker, J. Org. Chem., 1993, 58, 6394; H.-D. Becker,
H.-C. Becker and V. Langer, J. Photochem. Photobiol. A: Chem.,
1996, 97, 25; Y. Ito and G. Olovsson, J. Chem. Soc., Perkin Trans. 1,
1997, 127; C.-H. Tung, L.-Z. Wu, Z.-Y. Yuan and N. Su, J. Am.
Chem. Soc., 1998, 120, 11594.
[4 ؉ 4] Cycloadduct 3b. Colorless crystals; mp 178–181 ЊC
(from n-hexane–ethyl acetate) (Found: C, 85.80; H, 5.04; N,
2.57. C38H27NO2 requires C, 86.18; H, 5.14; N, 2.64%);
νmax(KBr)/cmϪ1 IR 1705 (C᎐O); δ (400 MHz; CDCl ; Me Si)
᎐
H
3
4
11 E. A. Chandross and C. J. Dempster, J. Am. Chem. Soc., 1970, 92,
704; G. Kaupp and I. Zimmermann, Angew. Chem., Int. Ed. Engl.,
1976, 15, 441; D. Döpp, C. Kruger, H. R. Memarian and Y.-H. Tsay,
Angew. Chem., Int. Ed. Engl., 1985, 24, 1048; T. Nishiyama,
K. Mizuno, Y. Otsuji and H. Inoue, Tetrahedron Lett., 1995, 51,
6695; T. Noh, D. Kim and Y.-J. Kim, J. Org, Chem., 1998, 63, 1212;
C.-H. Tung, Z.-Y. Yuan and L.-Z. Wu, J. Org. Chem., 1999, 64,
5156.
12 M. Lahav, F. Laub, E. Gati, L. Leiserowitz and Z. Ludmer, J. Am.
Chem. Soc., 1976, 98, 1620.
13 K. Okada, F. Samizo and M. Oda, Tetrahedron Lett., 1987, 33, 3819.
14 A. Itai, Y. Toriumi, N. Tomiokam, H. Kagechika, I. Azumaya and
K. Shudo, Tetrahedron Lett., 1989, 30, 6177; K. Yamaguchi,
G. Matsumura, H. Kagechika, Azumaya, Y. Ito, A. Itai and
K. Shudo, K. J. Am. Chem. Soc., 1991, 113, 547.
2.28 (3 H, d, J 7.3), 4.10 (1 H, ddd, J 10.9, 7.2 and 1.0), 4.49
(1 H, d, J 10.9), 5.81 (1 H, dd, J 8.5 and 1.2), 6.14 (1 H, dd,
J 8.5 and 7.2), 6.25 (1 H, d, J 7.5), 6.58 (1 H, td, J 7.8 and 1.2),
6.66 (2 H, q, J 7.3), 6.72–6.83 (5 H, m), 7.08–7.18 (3 H, m),
7.22 (1 H, d, J 7.0), 7.55–7.62 (2 H, m), 7.69 (1 H, td, J 7.0
and 1.4), 7.91 (1 H, d, J 8.2), 7.95 (1 H, d, J 8.3), 8.15 (1 H, d,
J 7.3) and 8.48 (1 H, d, J 8.6); δC(125 MHz; CDCl3; Me4Si)
17.87 (q), 47.58 (d), 48.05 (d), 53.07 (d), 63.35 (s), 66.80 (s),
123.20 (d), 124.44 (d), 124.59 (d), 125.24 (d), 125.32 (d), 125.50
(d), 125.75 (d), 126.11 (d), 126.44 (d), 126.58 (d), 126.90
(d), 126.97 (d), 127.20 (d), 127.24 (d), 127.26 (d), 128.95 (d),
129.19 (d), 131.13 (s), 133.62 (s), 133.90 (s), 134.13 (d), 137.71
(d), 139.81 (s), 140.89 (s), 141.17 (s), 142.88 (s), 143.08 (s),
143.75 (s), 176.56 (s) and 177.73 (s); m/z (EI) 529 (Mϩ,
18%), 374 (100), 331 (19), 303 (9), 205 (32), 177 (39), 155 (76)
and 127 (49).
15 Y. Mori and K. Maeda, Bull. Chem. Soc. Jpn., 1997, 70, 869.
16 Y. Mori and K. Maeda, J. Chem. Soc., Perkin Trans. 2, 1996, 113.
17 S. Kohmoto, H. Fukunaga, K. Yamaguchi, K. Kishikawa and
M. Yamamoto, unpublished work.
18 N. J. Turro, Modern Molecular Photochemistry, Benjamin
Cummings Publishing, Menlo Park, CA, 1978, p. 429 and references
cited therein.
References
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M. Yamamoto, unpublished work.
4468
J. Chem. Soc., Perkin Trans. 1, 2000, 4464–4468