Highly peri- and stereoselective intramolecular photocycloaddition and cyclisation of N-(1-naphthylethyl)prop-2-enamides

Article abstract of DOI:10.1039/b100678i

Control of three modes of intramolecular reactions, [2+2] and [4+2] cycloadditions, and Type-II cyclisation, is attempted in the photochemical reaction of N-(naphthylethyl)prop-2-enamides. The reactions are affected by the enamide substituents and the sen

Full text of DOI:10.1039/b100678i

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Highly peri- and stereoselective intramolecular photocycloaddition
and cyclisation of N-(1-naphthylethyl)prop-2-enamides
Shigeo Kohmoto,* Yoshiyuki Miyaji, Masaru Tsuruoka, Keiki Kishikawa, Makoto Yamamoto
and Kazutoshi Yamada
1
Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33,
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Received (in Cambridge, UK) 18th January 2001, Accepted 3rd July 2001
First published as an Advance Article on the web 9th August 2001
Control of three modes of intramolecular reactions, [2ϩ2] and [4ϩ2] cycloadditions, and Type-II cyclisation, is
attempted in the photochemical reaction of N-(naphthylethyl)prop-2-enamides. The reactions are affected by the
enamide substituents and the sensitisation conditions used. Acryloyl derivatives undergo [2ϩ2] cycloaddition and
Type-II cyclisation. The two reactions occur selectively depending on the sensitiser used, benzophenone sensitisation
affording the [2ϩ2] cycloadducts whereas the Type-II cyclisation products are obtained exclusively by benzene
sensitisation. In contrast, photolysis of cinnamoyl derivatives results in the formation of [4ϩ2] cycloadducts.
Introduction
Bichromophoric compounds have been investigated consider-
ably as models for the study of key photochemical processes,
especially for intramolecular energy-, electron-, or proton-
transfer.1 They may undergo different modes of photochemical
reaction depending on the excited state of the chromophore
involved. Control of the mode of photochemical reactions by
selective excitation of one of the chromophores is interest-
ing from both mechanistic and synthetic viewpoints. In order
to carry out the above-mentioned control of the mode of
photochemical reactions, either wavelength-dependent photo-
chemical reaction2 or selective sensitisation of chromophores
may be required.
As a part of our study of peri- and stereoselective organic
Fig. 1 Irradiation time-dependent product ratios of the photo-
photochemical reactions,3 we have investigated the control of
chemical reaction of 1b in benzene-d6 irradiated by a high-pressure Hg
three types of intramolecular reaction, viz. [2ϩ2] and [4ϩ2]
cycloadditions and Type-II cyclisation in the photoreaction of
N-(naphthylethyl)prop-2-enamide derivatives 1 based on selec-
tive sensitisation and substituent effect. One of the chromo-
phores of 1, the naphthalene π-system, is well known to act as
a 2π or 4π unit in [2ϩ2] or [4ϩ2] photocycloadditions with
alkenes, respectively,4 and also to undergo [3ϩ2] photocyclo-
addition at the 1,8- and 4,5-positions of the naphthalene
ring substituted with electron-withdrawing groups.5 The other
chromophore, the acrylamide moiety, reacts not only with the
naphthalene moiety as a 2π unit, but also undergoes Type-II
cyclisation via hydrogen abstraction by olefinic carbon.6 There-
fore, some different intramolecular photochemical reactions
could occur in this system.
lamp through Pyrex.
In order to confirm this, the progress of the reaction was moni-
tored by 1H NMR spectroscopy. Fig. 1 shows the results for 1b
in benzene-d6. In the early stage of the reaction, both 2b and 3b
were formed, but after 2 h, the amount of 2b started to
decrease, whereas the amount of 3b continued to increase,
which indicated that the formation of 3b was irreversible.
Further confirmation of a retro-[2ϩ2] photocycloaddition of
2b to 1b was achieved when 2b was irradiated in benzene-d6 and
the formation of 1b was observed (Fig. 2). In order to carry out
the photoreaction selectively, photosensitisation of the reaction
was examined. Since 1b has almost no absorption at 366 nm
(absorbance < 0.05) even at the initial concentration (6.7 × 10Ϫ2
M), no reaction was observed when the irradiation was carried
out through combination filters (cut-off range; 340 nm
< λ < 380 nm). In the direct irradiation through Pyrex filter, the
emitted light of 313 nm from a high-pressure Hg lamp should
be utilised for the photoreaction. Fig. 3 shows the UV spectra of
1b and 2b. However, addition of benzophenone as a sensitiser
afforded 2b without the formation of 3b (entry 3 in Table 1). In
contrast, benzene sensitisation of the reaction of 1b (irradiation
of 1b by a low-pressure Hg lamp, sample in benzene) resulted in
the exclusive formation of 3b accompanied by a tiny amount of
2b which was subsequently transformed to 3b via 1b (Fig. 4).
Thus, complete conversion of 1b to 3b was accomplished. It is
Results and discussion
Photoreaction of acryloyl derivatives
Irradiation of compounds 1a–c in benzene with a high-pressure
Hg lamp through Pyrex filter (λ > 280 nm) gave two types of
products, [2ϩ2] photocycloadducts, 2a–c, and azetidin-2-ones,
3a–c (for 3a as a diastereomeric mixture) derived from the
Type-II cyclisation (Scheme 1). The product ratio 2 : 3 depended
on irradiation time. Prolonged irradiation gave a higher yield of
3 and a lower yield of 2. The results indicated the presence of a
retro-[2ϩ2] photocycloaddition7 under the reaction conditions.
2082
J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b100678i

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Scheme 1
Fig. 4 Irradiation time-dependent product ratios of the photo-
Fig. 2 Irradiation time-dependent product ratios of the photo-
chemical reaction of 2b in benzene-d6 irradiated by a high-pressure Hg
lamp.
chemical reaction of 1b in benzene-d6 irradiated by a low-pressure Hg
lamp.
noteworthy that the Type-II cyclisation was the unique reaction
observed in benzophenone sensitisation of acrylamide with an
N-1-phenylethyl instead of an N-1-naphthylethyl group.8 How-
ever, in the present system, we did not observe any Type-II
cyclisation by benzophenone sensitisation; instead, the [2ϩ2]
cycloaddition was the unique reaction. Benzophenone might
sensitise the naphthyl group rather than the enone moiety,
whereas benzene might sensitise the enone more efficiently than
the naphthalene moiety for the Type-II cyclisation.
In order to apply this reaction for diastereoselective
[2ϩ2] photocycloaddition, p-methoxyacetophenone-sensitised
reactions of chiral molecules, 1d and 1e, were carried out.
p-Methoxyacetophenone was chosen as an easily separable
sensitiser from the products by silica gel chromatography.
Single diastereomers, 2d and 2e, were obtained in 78 and
82% yield from 1d and 1e, respectively. Their stereochemistry
was deduced from NOESY spectroscopy. The NOE relation
between the methyl of the pyrrolidin-2-one and the proton Ha
Fig. 3 The UV spectra of 1b and 2b in acetonitrile.
J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088
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Table 1 Isolated product yields in the intramolecular photochemical reaction of 1
Entry
Compd
R1
R2
R3a
Time (t/h)
2 (%)
3 (%)
4 (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
1a
1b
H
H
H
Me
Me
Me
8
5
19
58
82
47
78
82
0
0
0
0
0
59b
23
0
46
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.5c
8
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
H
H
H
Ph
Me
H
Me
H
H
H
H
H
H
H
Ph
Xc
Xc
Me
Me
Me
Xc
Xc
Xc
Xc
1d
1d
0
1.5
1.5
1.5
1.5
1.5
1.5
1.5
94
96
97
92
75
86
97
4-CH3OC6H4
4-NO2C6H4
Ph
4-ClC6H4
4-CH3OC6H4
3,4,5-(CH3O)3C6H2
0
0
a Xc = (S)-1-(1-naphthyl)ethylamino. b Diastereomer ratio; syn-3a : anti-3a = 4 : 5. c With one molar equiv. of benzophenone as sensitizer (340
nm < λ < 380 nm). d With one molar equiv. of p-methoxyacetophenone as sensitizer.
Fig. 5 Orientation of the double bond to the naphthalene moiety in
[2ϩ2] cycloaddition of 1.
established their relationship to be syn. The diastereoselectivity
was governed by the steric hindrance between the hydrogen
atom at the peri-position of the naphthalene ring and the
methyl of the 1-naphthylethyl group. In the two approaches of
the enone moiety to the naphthalene, approach A is preferable
to avoid the above-mentioned steric hindrance (Fig. 5).
Photoreaction of cinnamoyl derivatives
It is reported that substitution on the
β carbon of
α,β-unsaturated amides inhibits the hydrogen abstraction by
the β carbon under photolysis, causing no photochemical reac-
tion to occur.9 We did not observe the Type-II photocyclisation
in our cinnamoyl amide series, whereas we did find [4ϩ2]
cycloaddition. Irradiation of a benzene solution of 1f–l by a
high-pressure Hg lamp through a Pyrex filter afforded the
corresponding [4ϩ2] cycloadducts, 4f–l in 75–97% yield as a
single diastereomer. Benzophenone and benzene sensitisation
also resulted in the formation of [4ϩ2] cycloadducts with no
trace of the corresponding [2ϩ2] or Type-II cyclisation
products. Their stereochemistries were deduced by NOESY
spectroscopy. For the cycloadduct 4i, it is confirmed that the
methyl group is located cis to R2 (=H) and Hb, and away from
the peri-position of the naphthalene ring from the NOE
relations between the methyl and R2, the methyl and Hb, and R2
and Hb. The stereochemistry of the phenyl group (=R1) was
determined to be anti to the adjacent carbonyl from the NOE
relation between Hc and the phenyl (R1) proton. Among four
possible approaches (A–D) of the cinnamoyl double bond to
the naphthalene ring for the [4ϩ2] cycloaddition, the cyclo-
addition proceeded via approach A (Fig. 6). It is easily under-
stood that approaches B and D are unfavourable due to the
steric repulsion between the methyl group and the hydrogen
atom at the peri-position of the naphthalene moiety. Approach
C seems to be sterically unfavourable compared with approach
A. The heat of formation calculated by PM3 for 4c is 1.1 kcal
molϪ1† smaller than that for 6 which might be derived via
Fig. 6 Orientation of the double bond to the naphthalene moiety in
[4ϩ2] cycloaddition of 1.
approach C though it was not obtained. Since a [4ϩ2] cyclo-
addition is photochemically forbidden if the reaction is supra,
supra, the reaction should be stepwise. The biradical 5 might be
the intermediate in which the stereochemistry of the carbon
substituted with the phenyl group should be lost. Including the
stereochemistry of the phenyl group, eight possible diastere-
omers might be formed if there is no such stereocontrol.
In our cinnamoyl amides, only one diastereomer was
obtained out of eight possible ones. In order to investigate how
the Z–E configuration of the cinnamoyl double bond affects
the stereochemistry of the phenyl substituent, the progress of
1
the reaction of 1l was monitored by H NMR spectroscopy in
benzene-d6. We found that a Z–E isomerisation of 1l occurred
in addition to the [4ϩ2] cycloaddition. However, the resulting
[4ϩ2] cyloadduct 4l had the stereochemistry of the phenyl anti
to the adjacent carbonyl. For further confirmation of this fact,
the isolated cis-1l was irradiated under the same conditions.
The same [4ϩ2] cycloadduct 4l was obtained as a single
diastereomer. Since the radical site loses its original stereo-
chemical information, the same biradical intermediate should
be formed from both (E)-1l and (Z)-1l, which results in the
formation of the same sterically favourable cycloadduct. A
† 1 cal = 4.184 J.
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J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088

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thermal retro-[4ϩ2] cycloaddition of the [4ϩ2] adducts was
observed upon heating. The half-life of 1g was determined to
be 3.0 h at 150 ЊC in CDCl3 in a sealed tube by monitoring with
1H NMR spectroscopy.
MHz; CDCl3; Me4Si) 1.89 (3 H, d, J 6.9), 2.19 (3 H, s), 5.52
(1 H, dd, J 10.1 and 1.5), 6.04 (1 H, dd, J 17.0 and 1.5), 6.24 (1
H, dd, J 17.0 and 10.1), 6.52 (1 H, q, J 6.9), 7.41–7.54 (3 H, m),
7.63–7.68 (1 H, m) and 7.75–7.91 (3 H, m); δC (22.4 MHz;
CDCl3; Me4Si) 18.02 (q), 26.28 (q), 50.42 (d), 122.59 (d), 124.50
(d), 125.27 (d), 125.93 (d), 126.29 (d), 128.35 (d), 128.58 (d),
128.88 (t), 130.70 (s), 131.75 (d), 133.36 (s), 134.52 (s), 169.79
(s) and 172.38 (s); m/z (FAB) 268.1339 (MHϩ. C17H18NO2
requires m/z, 268.1337).
For the formation of the [4ϩ2] cycloadduct, the sensitised
photorearrangement of the [2ϩ2] to [4ϩ2] cycloadduct was
reported.10 However, the possibility of this kind of rearrange-
ment may be eliminated in our case, since the [2ϩ2] cyclo-
adducts obtained from acryloyl derivatives were stable under
irradiation with a sensitiser. Recently, photocycloaddition of
2-morpholinoacrylonitrile to substituted 1-acenaphthones was
reported to give [2ϩ2] or [4ϩ2] cycloadducts depending on the
position of the substituent at the naphthalene ring either at C-2
or C-4.11 The peri-selectivity was explained by steric hindrance
encountered in a proposed exciplex intermediate. Again, such a
steric effect is not the controlling factor in the present system.
Though the controlling factor to differentiate the mode of
reaction, either the [2ϩ2] or [4ϩ2] cycloaddition, is not yet
clear, it is possible to carry out three types of photochemical
reaction selectively in N-(naphthylethyl)prop-2-enamides. peri-
Selectivity of either the [2ϩ2] or [4ϩ2] cycloaddition is depend-
ent on the substituents of the enone moiety, acryloyl or
cinnamoyl. In acryloyl derivatives, two types of reactions are
possible, but both reactions can be induced selectively by sensi-
tisation. Stereoselectivity of the [2ϩ2] and [4ϩ2] photocyclo-
additions has been controlled perfectly.
N-(2-Methylprop-2-enoyl)-N-(1-naphthylethyl)acetamide 1b.
Colourless oil (52%); νmax (film)/cmϪ1 1705 (C᎐O) and 1664
᎐
(C᎐O); δ (400 MHz; CDCl ; Me Si) 1.72 (3 H, s), 1.90 (3 H, d,
᎐
H
3
4
J 7.0), 2.10 (3 H, s), 5.15 (1 H, s), 5.23 (1 H, s), 6.60 (1 H, q,
J 7.0), 7.40–7.86 (6 H, m) and 8.12 (1 H, d, J 8.5); δC (22.4 MHz;
CDCl3; Me4Si) 17.90 (q), 18.29 (q), 26.79 (q), 50.72 (d), 123.10
(d), 124.56 (t), 124.95 (d), 125.54 (d), 126.53 (d), 126.71 (d),
128.50 (d), 128.88 (d), 131.48 (s), 133.60 (s), 134.34 (s), 143.32
(s), 171.61 (s) and 175.46 (s); m/z (FAB) 282.1480 (MHϩ.
C18H20NO2 requires m/z, 282.1494).
N-(2-Methylprop-2-enoyl)-N-(1-naphthylethyl)benzamide 1c.
Colourless crystals (58%); mp 150–151 ЊC (Found: C, 80.62; H,
6.33; N, 4.09. C23H21NO2 requires C, 80.44; H, 6.16; N, 4.08%);
νmax (KBr)/cmϪ1 1695 (C᎐O) and 1650 (C᎐O); δ (90 MHz;
᎐
᎐
H
CDCl3; Me4Si) 1.39 (3 H, s), 2.04 (3 H, d, J 7.0), 4.95 (1 H, q,
J 1.5), 5.15 (1 H, q, J 1.5), 6.74 (1 H, q, J 7.0), 7.10–8.00 (11 H,
m) and 8.51 (1 H, d, J 7.9); δC (22.4 MHz; CDCl3; Me4Si) 17.93
(q), 18.02 (q), 51.91 (d), 122.50 (t), 122.98 (d), 124.71 (d), 125.21
(d), 126.23 (d), 126.80 (d), 128.29 (d), 128.67 (d), 131.36 (d),
133.45 (s), 134.31 (s), 138.25 (s), 144.52 (s), 173.28 (s) and and
174.20 (s); m/z (FAB) 344.1658 (MHϩ. C23H22NO2 requires m/z,
344.1650).
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
EX-90, FX-270 and GSX-400 spectrometers for samples in
CDCl3 with Me4Si as an internal standard; J-values are given in
Hz. Mass spectra were measured with an Hitachi RMU-7M
mass spectrometer. Optical rotations were measured on a
Horiba SEPA 300 polarimeter; [α]D-values are given in units
of 10Ϫ1 deg cm2 gϪ1. Elemental analyses were performed on a
Perkin-Elmer 240 analyser. Reaction solutions were concen-
trated on a rotary evaporator at 10–15 mmHg. Chromato-
graphic separation was accomplished by flash column chrom-
atography on silica gel (Fuji gel BW 200; 150–350 mesh) and
further purification was carried out by a preparative HPLC run;
column Merck Si 60 (7 µm; 10 × 250 mm), hexane–ethyl acetate
as eluent. All solvents were freshly distilled and stored over 4 Å
molecular sieves.
N-[(1S)-1-Naphthylethyl]-N-{[(1S)-1-naphthylethyl]-
carbamoyl}prop-2-enamide 1d. Colourless amorphous (34%);
mp 49–51 ЊC; [α]D21 Ϫ81.7 (c 1.00 in CHCl3); νmax (KBr)/cmϪ1
3284 (NH), 1698 (C᎐O), 1658 (C᎐O) and 1620 (C᎐C); δ (270
᎐
᎐
᎐
H
MHz; CDCl3; Me4Si) 1.42 (1 H, d, J 7.3), 1.87 (3 H, d, J 7.3),
5.60 (1 H, dq, J 7.3 and 7.3), 5.67 (1 H, dd, J 8.8 and 3.1), 6.07
(1 H, d, J 7.3), 6.39 (1 H, dd, J 17.0 and 3.1), 6.49 (1 H, dd,
J 17.0 and 8.8), 6.53 (1 H, q, J 7.3), 6.70 (1 H, d, J 7.3), 6.92
(1 H, t, J 7.7) and 7.10–7.92 (13 H, m); δC (22.4 MHz; CDCl3;
Me4Si) 17.93 (q), 20.88 (q), 46.18 (d), 49.40 (d), 121.84 (d),
122.77 (d), 124.65 (d), 125.15 (d), 125.57 (d), 125.63 (d), 126.32
(d), 126.80 (d), 127.96 (d), 128.59 (d), 128.67 (d), 128.85 (t),
129.36 (d), 130.38 (s), 131.00 (s), 133.48 (s), 133.75 (s), 134.49
(s), 137.27 (s), 153.56 (s) and 166.15 (s); m/z (EI) 422.1999 (Mϩ.
C28H26N2O2 requires M, 422.1996).
General procedure for the preparation of N-(1-naphthylethyl)-
prop-2-enamides 1
N-[(1S)-1-Naphthylethyl]-N-{[(1S)-1-naphthylethyl]-
carbamoyl}-2-methylprop-2-enamide 1e. Colourless crystals
(40%); mp 122–123 ЊC (Found: C, 79.69; H, 6.47; N, 6.17.
C29H28N2O2 requires C, 79.79; H, 6.47; N, 6.42%); [α]2D1 ϩ16.1
Achiral enamides were prepared as follows. To a solution of the
carboxamide, prepared from ( )-1-(1-naphthyl)ethylamine and
acryloyl chloride or cinnamoyl chloride (2 mmol), in benzene
(30 cm3) was added triethylamine (1.2 equiv.) at room temper-
ature. To the resulting solution was added dropwise acetyl
chloride or benzoyl chloride (1.2 equiv.). The resulting mixture
was refluxed overnight and was then quenched with saturated
aq. NaHCO3 (30 cm3) and washed successively with 1 M hydro-
chloric acid (30 cm3) and brine (30 cm3). The organic layer was
dried (MgSO4), and concentrated in vacuo. The products were
separated by column chromatography on silica gel [ethyl
acetate–hexane (1 : 4)]. Crystalline compounds were recrystal-
lised from ethyl acetate–hexane (≈1 : 7).
(c 1.02 in CHCl3); νmax (KBr)/cmϪ1 3364 (NH), 1700(C᎐O),
᎐
1648 (C᎐O), and 1624 (C᎐C); δ (270 MHz; CDCl ; Me Si) 1.30
᎐
᎐
H
3
4
(3 H, d, J 7.0), 1.70 (3 H, d, 7.0), 2.00 (3 H, s), 4.85 (1 H, d,
J 7.0), 5.15 (1 H, s), 5.22 (1 H, s), 5.50 (1 H, dq, J 7.0 and 7.0),
6.41 (1 H, q, J 7.0), 6.60–6.74 (2 H, m), 6.87 (1 H, d, J 7.0),
7.20–7.30 (2 H, m) and 7.40–8.00 (9 H, m); δC (22.4 MHz;
CDCl3; Me4Si) 17.36 (q), 19.57 (q), 20.02 (q), 45.76 (d), 48.81
(d), 116.65 (t), 122.02 (d), 122.95 (d), 123.07 (d), 124.65 (d),
125.15 (d), 125.84 (d), 126.53 (d), 126.88 (d), 128.23 (d), 128.61
(d), 128.79 (d), 128.88 (d), 130.61 (s), 131.09 (s), 133.57 (s),
133.84 (s), 134.52 (s), 136.94 (s), 142.46 (s), 154.21 (s) and
172.44 (s); m/z (EI) 438 (M ϩ 2, 2%), 437 (M ϩ 1, 1), 436 (Mϩ,
5), 282 (15), 238 (12), 224 (9), 195 (15), 182 (12), 170 (25) and
100 (100).
Chiral enamides, 1d, 1e, 1i, 1j, 1k and 1l, were prepared as
reported12 from N,NЈ-bis[(S)-1-naphthylethyl]carbodiimide
with the appropriate carboxylic acids.
N-(1-Naphthylethyl)-N-prop-2-enoylacetamide 1a. Colourless
oil (65%); νmax (film)/cmϪ1 1690 (C᎐O) and 1616 (C᎐C); δH (400
N-(1-Naphthylethyl)-N-[(E )-3-phenylprop-2-enoyl]acetamide
1f. Colourless oil (55%); νmax (film)/cmϪ1 1695 (C᎐O), 1660
᎐
᎐
᎐
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(C᎐O) and 1620 (C᎐C), 1510, 1455, 1375, 1335, 1265, 1190,
166.36 (s); m/z (EI) 532.1910 (Mϩ. C34H2935ClN2O2 requires M,
᎐
᎐
1115, 1085, 1025, 980 and 770; δH (270 MHz; CDCl3; Me4Si)
1.92 (3 H, d, J 7.0), 2.27 (3 H, s), 6.41 (1 H, d, J 16.2), 6.63 (1 H,
q, J 7.0), 7.28 (1 H, d, J 16.2), 7.20–7.83 (11 H, m) and 7.97
(1 H, d, J 8.5); δC (22.4 MHz; CDCl3; Me4Si) 18.40 (q), 26.25
(q), 50.33 (d), 122.05 (d), 123.10 (d), 124.74 (d), 125.66 (d),
126.02 (d), 126.65 (d), 128.02 (d), 128.70 (d), 128.88 (d), 130.43
(d), 131.12 (s), 133.72 (s), 133.96 (s), 134.97 (s), 144.25
(d), 170.95 (s) and 172.38 (s); m/z (FAB) 344.1638 (MHϩ.
C23H22NO2 requires m/z, 344.1650).
532.1917).
N-[(E )-3-(4-Methoxyphenyl)prop-2-enoyl]-N,NЈ-bis[(1S)-1-
naphthylethyl]urea 1k. Colourless solid (71%); [α]2D1 ϩ126.0
(c 1.41 in CHCl3); νmax (KBr)/cmϪ1 3350 (NH), 1692 (C᎐O),
᎐
1650 (C᎐O) and 1600 (C᎐C); δ (270 MHz; CDCl ; Me Si) 1.52
᎐
᎐
H
3
4
(3 H, d, J 7.0), 1.88 (3 H, d, J 7.0), 3.80 (3 H, s), 5.72 (1 H, dq,
J 7.0 and 7.0), 6.59 (1 H, d, J 15.4), 6.63 (1 H, q, J 7.0), 6.77–
6.84 (3 H, m), 7.05–7.13 (1 H, m), 7.58 (1 H, d, J 15.4) and 7.20–
8.00 (15 H, m); δC (22.4 MHz; CDCl3; Me4Si) 18.22 (q), 21.30
(q), 46.21 (d), 49.67 (d), 55.16 (q), 114.08 (d), 116.74 (d), 121.81
(d), 122.80 (d), 122.92 (d), 124.62 (d), 125.15 (d), 125.45 (d),
126.26 (d), 126.67 (d), 127.24 (s), 127.81 (d), 128.46 (d), 128.61
(d), 128.76 (d), 129.51 (d), 130.34 (s), 131.06 (s), 133.51 (s),
133.72 (s), 135.18 (s), 137.56 (s), 143.26 (s), 154.00 (s), 161.07 (s)
and 167.01 (s); m/z (FAB) 529.2940 (MHϩ. C35H33N2O3 requires
m/z, 529.2942).
N-[(E )-3-(4-Methoxyphenyl)prop-2-enoyl]-N-(1-naphthyl-
ethyl)acetamide 1g. Colourless oil (63%); νmax (film)/cmϪ1 1740
(C᎐O), 1660 (C᎐O) and 1600 (C᎐C); δ (270 MHz; CDCl3;
᎐
᎐
᎐
H
Me4Si) 1.92 (3 H, d, J 7.0), 2.26 (3 H, s), 3.78 (3 H, s), 6.22 (1 H,
d, J 15.6), 6.64 (1 H, q, J 7.0), 6.80 (2H, dt, J 8.6 and 2.2), 7.16
(2 H, d, J 8.6), 7.22 (1 H, d, J 15.6), 7.36–7.58 (3H, m), 7.67
(1H, d, J 7.4), 7.73 (1H, d, J 8.4), 7.81 (1H dd, J 8.4 and 1.5)
and 8.00 (1 H, d, J 8.4); δC (22.4 MHz; CDCl3; Me4Si) 18.34 (q),
26.01 (q), 50.12 (d), 55.13 (q), 114.08 (d), 119.64 (d), 123.12 (d),
124.71 (d), 125.51 (d), 125.93 (d), 126.53 (d), 128.52 (d), 128.79
(d), 129.78 (d), 131.15 (s), 133.63 (s), 135.03 (s), 144.37 (d),
161.52 (s), 171.25 (s) and 171.99 (s); m/z (FAB) 374.1766 (MHϩ.
C24H24NO3 requires m/z, 374.1761).
N,NЈ-Bis[(IS)-1-naphthylethyl]-N-[(E )-3-(3,4,5-trimethoxy-
phenyl)prop-2-enoyl]urea 1l. Colourless crystals (34%); mp 149–
150 ЊC (Found: C, 75.22; H, 6.35; N, 4.51. C37H36N2O5 requires
C, 75.49; H, 6.16; N, 4.76%); [α]2D1 ϩ114.0 (c 0.71 in CHCl3);
νmax (KBr)/cmϪ1 3420 (NH), 1700 (C᎐O), 1655 (C᎐O), 1610
᎐
᎐
(C᎐C); δ (400 MHz; CDCl3; Me4Si) 1.55 (3 H, d, J 6.8), 1.89
᎐
H
N-(1-Naphthylethyl)-N-[(E )-3-(4-nitrophenyl)prop-2-enoyl]-
acetamide 1h. Yellow crystals (46%); mp 128–129 ЊC (Found: C,
71.26; H, 5.19; N, 7.26. C23H20N2O4 requires C, 71.12; H, 5.19;
N, 7.21%); νmax (KBr)/cmϪ1 1685 (C᎐O) 1625 (C᎐C), 1520
(NO2) and 1380 (NO2); δH (270 MHz; CDCl3; Me4Si) 1.93 (3 H,
d, J 7.0), 2.27 (3 H, s), 6.59 (1 H, d, J 15.4), 6.60 (1 H, q, J 7.0),
7.30 (1 H, d, J 15.4), 7.35–7.90 (9 H, m) and 8.15 (2 H, d, J 8.5);
δC (22.4 MHz; CDCl3; Me4Si) 18.43 (q), 26.19 (q), 50.63 (d),
122.89 (d), 123.84 (d), 124.74 (d), 125.87 (d), 126.82 (d), 128.44
(d), 128.97 (d), 130.85 (s), 133.72 (s), 134.85 (s), 139.98 (d),
140.28 (s), 148.19 (s), 169.73 (s) and 173.04 (s); m/z (FAB)
389.1498 (MHϩ. C23H21N2O4 requires m/z, 389.1501).
(3 H, d, J 7.0), 3.83 (6 H, s), 3.87 (3 H, s), 5.71 (1 H, dq, J 7.0
and 7.0 Hz), 6.62 (1 H, q, J 6.8), 6.63 (1 H, d, J 15.0), 6.75 (1 H,
br s), 6.85 (1 H, d, J 7.2), 7.03–7.08 (1 H, m), 7.61 (1 H, d,
J 15.0), 7.20–7.80 (14 H, m); δC (22.4 MHz; CDCl3; Me4Si)
18.26 (q), 21.24 (q), 46.18 (d), 49.70 (d), 55.73 (q), 60.59 (q),
104.87 (d), 118.32 (d), 121.66 (d), 122.59 (d), 124.59 (d), 125.06
(d), 125.36 (d), 125.45 (d), 126.17 (d), 126.59 (d), 127.72 (d),
128.35 (d), 128.53 (d), 128.67 (d), 129.84 (s), 130.41 (s), 130.85
(s), 133.36 (s), 133.57 (s), 135.09 (s), 137.39 (s), 139.62 (s),
143.41 (d), 153.00 (d), 153.83 (s) and 166.33 (s); m/z (FAB)
589.2696 (MHϩ. C37H37N2O5 requires m/z, 589.2703).
᎐
᎐
N,NЈ-Bis[(IS)-1-naphthylethyl]-N-[(Z )-3-(3,4,5-trimethoxy-
phenyl)prop-2-enoyl]urea [(Z )-1l]. Colourless oil; νmax (KBr)/
cmϪ1 3440 (NH), 1710 (C᎐O), 1650 (C᎐O) and 1585 (C᎐C);
δH (400 MHz; CDCl3; Me4Si) 1.56 (3 H, d, J 6.8), 1.89 (3 H, d,
J 7.0), 3.61 (6 H, s), 3.84 (3 H, s), 5.70 (1 H, dq, J 7.0 and
7.0), 5.89 (1 H, d, J 12.6), 6.42 (1 H, d, J 12.6), 6.53 (1 H, q,
J 6.8), 6.57 (2 H, s), 6.96 (1 H, d, J 7.0) and 7.20–7.90 (14 H,
m); m/z (FAB) 589.2700 (MHϩ. C37H37N2O5 requires m/z,
589.2703).
N,NЈ-Bis[(1S)-1-naphthylethyl]-N-[(2E)-3-phenylprop-2-
enoyl]urea 1i. Colourless crystals (56%); mp 164–165 ЊC
(Found: C, 82.14; H, 6.05; N, 5.99. C34H30N2O2 requires C,
81.90; H, 6.06; N, 5.62%); [α]2D1 ϩ88.6 (c 0.90 in CHCl3); νmax
(KBr)/cmϪ1 3344 (NH), 1708 (C᎐O), 1652 (C᎐O) and 1610 (C᎐
᎐
C); δH (270 MHz; CDCl3; Me4Si) 1.52 (3 H, d, J 7.0), 1.89 (3 H,
d, J 7.0), 5.70 (1 H, dq, J 7.0 and 7.0), 6.55 (1 H, br s), 6.64 (1 H,
q, J 7.0), 6.75 (1 H, d, J 15.4), 6.81 (1 H, d, J 7.3), 7.00–7.10
(1 H, m), 7.65 (1 H, d, J 15.4) and 7.20–8.00 (17 H, m); δC (22.4
MHz; CDCl3; Me4Si) 18.34 (q), 21.39 (q), 46.36 (d), 49.79 (d),
119.43 (d), 121.99 (d), 122.95 (d), 123.01 (d), 124.77 (d), 125.30
(d), 125.66 (d), 125.72 (d), 126.47 (d), 126.88 (d), 127.99 (d),
128.67 (d), 128.79 (d), 128.94 (d), 130.05 (d), 130.52 (s), 131.18
(s), 133.67 (s), 133.87 (s), 134.64 (s), 135.18 (s), 137.63 (s),
143.56 (d), 154.00 (s) and 166.83 (s); m/z (EI) 499 (M ϩ 1, 3%),
344 (2), 302 (2), 197 (31), 182 (54), 170 (75), 155 (77), 131 (100)
and 103 (65).
᎐
᎐
᎐
᎐
᎐
General procedure for the photochemical reaction of 1
Preparative photochemical reactions were carried out in ben-
zene (15 cm3) with ca. 1.0 mmol of an enamide 1 in a Pyrex test
tube (1.5 cm diameter × 16.5 cm) under bubbling of argon
irradiated externally using a Ushio 450 W high-pressure
mercury lamp. The reaction tube was cooled externally in a
water-bath. For the reaction of 1d and 1e, p-methoxyaceto-
phenone (1 equiv.) was added as a sensitiser. The progress of the
reaction was monitored by TLC. After irradiation, the solvent
was removed in vacuo. The products were separated by column
chromatography on silica gel [ethyl acetate–hexane (1 : 4)]. The
[2ϩ2] cycloadducts 2 and azetidin-2-ones 3 were separated and
purified by HPLC [ethyl acetate–hexane (1 : 6)]. The crystalline
compounds were recrystallised from ethyl acetate–hexane
(≈1 : 7).
N-[(E )-3-(4-Chlorophenyl)prop-2-enoyl]-N,NЈ-bis[(1S)-1-
naphthylethyl]urea 1j. Colourless crystals (90%); mp 164.5–
165.5 ЊC; [α]D21 ϩ105.8 (c 1.33 in CHCl3); νmax (KBr)/cmϪ1 3260
(NH), 1708 (C᎐O), 1658 (C᎐O) and 1616 (C᎐C); δH (270 MHz;
᎐
᎐
᎐
CDCl3; Me4Si) 1.51 (3 H, d, J 7.0), 1.86 (3 H, d, J 7.0), 5.71
(1 H, dq, J 7.0 and 7.0), 6.46 (1 H, s), 6.64 (1 H, q, J 7.0), 6.69
(1 H, d, J 15.4), 6.85 (1 H, d, J 7.3), 7.00–7.10 (1 H, m), 7.59
(1 H, d, J 15.4), 7.15–8.00 (16 H, m); δC (22.4 MHz; CDCl3;
Me4Si) 18.29 (q), 21.18 (q), 46.24 (d), 49.79 (d), 117.10 (d),
119.78 (d), 122.14 (d), 122.89 (d), 124.83 (d), 125.27 (d), 125.48
(d), 125.66 (d), 125.75 (d), 126.53 (d), 126.82 (d), 128.08 (d),
128.64 (d), 128.79 (d), 128.91 (d), 129.00 (d), 129.33 (d), 129.63
(d), 130.55 (s), 131.09 (s), 132.94 (s), 133.63 (s), 133.84 (s),
135.39 (s), 135.75 (s), 137.45 (s), 141.95 (d), 153.86 (s) and
1
The monitoring experiments by H NMR spectroscopy (90
MHz) were performed on ca. 0.1 M 1 in benzene-d6. The sample
solution was purged by argon for 15 min prior to irradiation.
For benzophenone sensitisation, a combination of glass filters,
Toshiba UV-35 and UV-D36A (340 nm < λ < 380 nm), was
applied to select the 366 nm mercury arc light. A Ushio 6 W
low-pressure mercury lamp was used for the 254 nm irradiation.
2086
J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088

View Article Online
[2؉2] Cycloadduct 2a. Colourless crystals; mp 131.5–
132.5 ЊC (Found: C, 76.68; H, 6.34; N, 5.03. C17H17NO2
(s), 134.34 (s), 138.91 (s), 152.27 (s) and 181.60 (s); m/z (EI)
436.2143 (Mϩ. C29H28N2O2 requires M, 436.2152).
requires C, 76.38; H, 6.41; N, 5.24%); νmax (KBr)/cmϪ1 1734 (C᎐
᎐
O) and 1690 (C᎐O); δH (270 MHz; CDCl3; Me4Si) 1.32 (3 H, d,
The azetidin-2-one syn-3a. Colourless crystals; mp 139–
140 ЊC (Found: C, 76.28; H, 6.25; N, 5.18. C17H17NO2 requires
᎐
J 6.2), 2.32 (1 H, ddd, J 11.3, 8.5, 1.7), 2.50 (1 H, ddd, J 11.3,
10.0, 8.9), 2.60 (3 H, s), 3.24 (1 H, m), 3.36 (1 H, m), 4.24 (1 H,
q, J 6.2), 5.83 (1 H, dd, J 9.9, 5.9), 6.33 (1 H, d, J 9.9), 7.06–7.10
(1 H, m) and 7.10–7.28 (3 H, m); δC (22.4 MHz; CDCl3; Me4Si)
13.81 (q), 26.22 (q), 31.47 (t), 34.13 (d), 45.91 (s), 53.82 (d),
64.08 (d), 127.15 (d), 127.27 (d), 127.72 (d), 128.29 (d), 133.63
(s), 134.19 (s), 172.44 (s) and 177.75 (s).
C, 76.38; H, 6.41; N, 5.24%); νmax (KBr)/cmϪ1 1790 (C᎐O) and
᎐
1700 (C᎐O); δH (270 MHz; CDCl3; Me4Si) 0.94 (3 H, q, J 7.6),
᎐
2.25 (3 H, s), 2.62 (3 H, s), 3.60 (1 H, q, J 7.6), 7.23–7.53 (4 H,
m), 7.68–7.92 (3 H, m); δC (22.4 MHz; CDCl3; Me4Si) 11.66 (q),
25.39 (q), 25.65 (q), 56.98 (d), 68.86 (s), 125.06 (d), 125.24 (d),
125.30 (d), 125.48 (d), 128.67 (d), 129.36 (d), 129.57 (s), 134.28
(s), 134.37 (s), 169.37 (s) and 169.97 (s); m/z (FAB) 268.1332
(MHϩ. C17H18NO2 requires m/z, 268.1337).
[2؉2] Cycloadduct 2b. Colourless crystals; mp 129–130 ЊC
(Found: C, 77.01; H, 6.94; N, 5.00. C18H19NO2 requires C,
76.84; H, 6.81; N, 4.98%); νmax (KBr)/cmϪ11724 (C᎐O) and 1706
The azetidin-2-one anti-3a. Colourless crystals; mp 135.5–
136.5 ЊC (Found: C, 76.04; H, 6.34; N, 5.14. C17H17NO2
requires C, 76.38; H, 6.41; N, 5.24%); νmax (KBr)/cmϪ1 1785
᎐
(C᎐O); δ (400 MHz; CDCl ; Me Si) 1.12 (3 H, s), 1.30 (3 H, d,
᎐
H
3
4
J 7.0), 1.95 (1 H, dd, J 11.2 and 10.0), 2.45 (1 H, dd, J 11.2 and
8.5), 2.60 (3 H, s), 3.20 (1 H, ddd, J 10.0, 8.5 and 5.8), 4.19 (1 H,
q, J 7.0), 5.83 (1 H, dd, J 10.0 and 5.8), 6.30 (1 H, d, J 10.0),
7.00–7.12 (2 H, m) and 7.20–7.30 (2 H, m); δC (22.4 MHz;
CDCl3; Me4Si) 13.81 (q), 18.85 (q), 26.34 (d), 31.92 (q), 39.41
(t), 49.46 (s), 56.00 (s), 62.65 (d), 126.85 (d), 127.48 (d), 127.63
(d), 127.72 (d), 127.78 (d), 128.61 (d), 130.97 (s), 134.37 (s),
172.74 (s) and 180.71 (s); m/z (EI) 282 (M ϩ 1, 4%), 281 (Mϩ,
12), 238 (14), 212 (39), 170 (41), 155 (39), 127 (18), 69 (55) and
43 (100).
(C᎐O) and 1705 (C᎐O); δ (270 MHz; CDCl ; Me Si) 1.69 (3 H,
᎐
᎐
H
3
4
d, J 7.6), 2.06 (3 H, s), 2.60 (3 H, s), 3.41 (1 H, q, J 7.6), 7.35–
7.56 (4 H, m), 7.60–7.65 (1 H, m), 7.75–7.82 (1 H, m) and 7.85–
7.95 (1 H, m); δC (22.4 MHz; CDCl3; Me4Si) 10.50 (q), 19.66
(q), 25.27 (q), 55.22 (d), 67.84 (s), 123.60 (d), 123.75 (d), 125.15
(d), 125.36 (d), 125.90 (d), 128.50 (d), 129.00 (s), 129.63 (d),
134.28 (s), 139.21 (s), 169.46 (s) and 169.94 (s); m/z (FAB)
268.1330 (MHϩ. C17H18NO2 requires m/z, 268.1337).
The azetidin-2-one 3b. Colourless oil; νmax (film)/cmϪ1 1784
[2؉2] Cycloadduct 2c. Colourless crystals; mp 161–162 ЊC
(C᎐O) and 1708 (C᎐O); δ (270 MHz; CDCl ; Me Si) 0.92 (3 H,
᎐ ᎐
H 3 4
(Found: C, 80.53; H, 6.21; N, 3.96. C23H21NO2 requires C,
s), 1.70 (3 H, s), 2.15 (3 H, s), 2.62 (3 H, s) and 7.20–7.90 (7 H,
m); δC (22.4 MHz; CDCl3; Me4Si) 18.20 (q), 20.31 (q), 22.19 (q),
25.57 (q), 57.55 (s), 72.29 (s), 124.41 (d), 125.00 (d), 125.24 (d),
125.30 (d), 125.51 (d), 128.41 (d), 129.36 (d), 129.90 (s), 134.37
(s), 136.55 (s), 169.55 (s) and 173.28 (s); m/z (FAB) 282.1488
(MHϩ. C18H20NO2 requires m/z, 282.1494).
80.44; H, 6.16; N, 4.08%); νmax (KBr)/cmϪ1 1730 (C᎐O) and
᎐
1675 (C᎐O); δ (270 MHz; CDCl3; Me4Si) 1.07 (3 H, s), 1.29
᎐
H
(3 H, d, J 6.3), 2.03 (1 H, dd, J 11.4 and 10.3), 2.56 (1 H, dd,
J 11.4 and 8.7), 3.47 (1 H, ddd, J 10.3, 8.7 and 5.5), 4.41 (1 H, q,
J 6.3), 5.90 (1 H, dd, J 9.9 and 5.5), 6.34 (1 H, d, J 9.9), 7.04–
7.12 (2 H, m), 7.22–7.27 (2 H, m), 7.42–7.50 (2 H, m), 7.53–7.61
(1 H, m) and 7.75–7.80 (2 H, m); δC (22.4 MHz; CDCl3; Me4Si)
12.29 (q), 18.46 (q), 31.65 (d), 39.88 (t), 49.82 (s), 55.73 (s),
62.20 (s), 126.85 (d), 127.39 (d), 127.69 (d), 127.75 (d), 127.84
(d), 128.08 (d), 128.52 (d), 129.27 (d), 130.67 (s), 132.64 (d),
134.25 (s), 135.03 (s), 171.82 (s) and 179.66 (s); m/z (FAB)
344.1646 (MHϩ. C23H22NO2 requires m/z, 344.1651).
The azetidin-2-one 3c. Colourless solid; νmax (KBr)/cmϪ1 1790
(C᎐O) and 1680 (C᎐O); δH (90 MHz; CDCl3; Me4Si) 1.03 (3 H,
᎐
᎐
s), 1.70 (3 H, s), 2.32 (3 H, s), 7.20–8.10 (12 H, m); δC (22.4
MHz; CDCl3; Me4Si) 18.05 (q), 20.88 (q), 23.33 (q), 56.95 (s),
72.05 (s), 124.05 (d), 125.06 (d), 125.33 (d), 125.42 (d), 125.63
(d), 128.08 (d), 128.41 (d), 129.42 (d), 129.60 (d), 129.99 (s),
133.00 (d), 133.78 (s), 134.52 (s), 136.82 (s), 168.18 (s) and
171.99 (s); m/z (FAB) 344.1645 (MHϩ. C23H22NO2 requires m/z
344.1651).
[2؉2] Cycloadduct 2d. Colourless solid; [α]2D1 Ϫ48.3 (c 0.58
in CHCl3); νmax (KBr)/cmϪ1 3284 (NH) and 1712 (C᎐O); δ (400
᎐
H
MHz; CDCl3; Me4Si) 1.39 (3 H, d, J 6.2), 1.72 (3 H, d, J 7.7),
2.25 (1 H, ddd, J 11.6, 8.5 and 1.5), 2.45 (1 H, ddd, J 11.6, 9.3
and 9.3), 3.30 (2 H, m), 4.35 (1 H, q, J 6.2), 5.75 (1 H, dd, J 9.6
and 6.2), 5.95 (1 H, dq, J 7.7 and 7.7), 6.30 (1 H, d, J 9.6), 7.01
(1 H, d, J 7.2), 7.15–7.65 (7 H, m), 7.80 (1 H, d, J 8.3), 7.88 (1 H,
d, J 8.3), 8.19 (1 H, d, J 8.5) and 8.96 (1 H, d, J 8.0); δC (22.4
MHz; CDCl3; Me4Si) 14.38 (q), 21.98 (q), 31.35 (t), 33.98 (d),
45.58 (d), 46.03 (s), 54.30 (d), 64.77 (d), 122.53 (d), 123.24 (d),
125.39 (d), 125.66 (d), 126.29 (d), 127.15 (d), 127.72 (d), 128.08
(d), 128.29 (d), 128.85 (d), 130.82 (s), 133.66 (s), 133.96 (s),
134.19 (s), 138.82 (s), 152.15 (s) and 178.86 (s); m/z (EI)
422.2003 (Mϩ; C28H26N2O2 requires M, 422.1996).
[4؉2] Adduct 4f. Colourless crystals; mp 188.5–189.5 ЊC
(Found: C, 80.08; H, 6.24; N, 3.90. C23H21NO2 requires C,
80.44; H, 6.16; N, 4.08%); νmax (KBr)/cmϪ1 1755 (C᎐O) and
᎐
1695 (C᎐O); δH (270 MHz; CDCl3; Me4Si) 1.57 (3 H, d, J 6.6),
᎐
2.42 (3 H, s), 2.98 (1 H, d, J 7.0), 3.14 (1 H, dd, J 7.0 and 1.5),
4.22 (1 H, ddd, J 5.4, 1.5 and 1.5), 5.44 (1 H, q, J 6.6), 6.72 (1 H,
dd, J 8.0 and 5.4), 6.79 (1 H, dd, J 8.0 and 1.5) and 7.10–7.40
(9 H, m); δC (22.4 MHz; CDCl3; Me4Si) 14.29 (q), 25.12 (q),
46.24 (d), 47.31 (d), 50.75 (s), 51.82 (d), 57.49 (d), 121.25 (d),
122.47 (d), 125.66 (d), 126.47 (d), 126.71 (d), 127.18 (d), 128.64
(d), 134.61 (d), 134.88 (d), 138.76 (s), 143.50 (s), 146.93 (s),
170.95 (s) and 173.43 (s); m/z (FAB) 344.1647 (MHϩ.
C23H22NO2 requires m/z, 344.1650).
[2؉2] Cycloadduct 2e. Colourless solid; [α]2D1 Ϫ15.3 (c 0.88 in
CHCl3); νmax (KBr)/cmϪ1 3480 (NH) and 1712 (C᎐O); δ (400
᎐
H
MHz; CDCl3; Me4Si) 1.13 (3 H, s), 1.36 (3 H, d, J 6.2), 1.72
(3 H, d, J 7.0), 1.88 (1 H, dd, J 11.2 and 10.0), 2.38 (1 H, dd,
J 11.2 and 8.5), 3.15 (1 H, ddd, J 10.0, 8.5 and 5.8), 4.29 (1 H, q,
J 6.2), 5.78 (1 H, dd, J 10.4 and 5.8), 5.93 (1 H, dq, J 7.7 and
7.7), 6.28 (1 H, d, J 10.4), 7.00–7.30 (4 H, m), 7.45–7.60 (4 H,
m), 7.80 (1 H, d, J 8.1), 7.89 (1 H, d, J 8.1), 8.19 (1 H, d, J 8.5)
and 8.90 (1 H, d, J 7.7); δC (22.4 MHz; CDCl3; Me4Si) 14.35 (q),
18.70 (q), 22.01 (q), 31.65 (d), 39.23 (t), 45.58 (d), 49.52 (s),
56.47 (s), 63.34 (d), 122.47 (d), 123.21 (d), 125.39 (d), 125.66
(d), 126.29 (d), 126.77 (d), 127.45 (d), 127.57 (d), 127.66 (d),
127.72 (d), 128.02 (d), 128.73 (d), 128.85 (d), 130.85 (s), 133.96
[4؉2] Adduct 4g. Colourless crystals; mp 163.5–164.5 ЊC
(Found: C, 77.18; H, 6.06; N, 3.65. C24H23NO3 requires C,
77.19; H, 6.21; N, 3.75%); νmax (KBr)/cmϪ1 1745 (C᎐O) and
᎐
1700 (C᎐O); δ (90 MHz; CDCl3; Me4Si) 1.58 (3 H, d, J 6.5),
᎐
H
2.41 (3 H, s), 2.95 (1 H, d, J 6.9), 3.09 (1 H, dd, J 6.9 and 1.5),
3.79 (3 H, s), 4.19 (1 H, ddd, J 5.6, 1.5 and 1.5), 5.44 (1 H, q,
J 6.5), 6.71 (1 H, dd, J 7.7 and 5.6), 6.79 (1 H, dd, J 7.7 and 1.5),
6.86 (2 H, d, J 8.6), 7.26 (2 H, d, J 8.6) and 7.28 (4 H, m);
δC (22.4 MHz; CDCl3; Me4Si) 14.20 (q), 25.03 (q), 45.40 (d),
47.55 (d), 50.63 (s), 51.73 (d), 55.10 (q), 57.52 (d), 113.94 (d),
121.13 (d), 122.35 (d), 125.51 (d), 126.35 (d), 128.08 (d), 134.52
J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088
2087

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(d), 134.79 (d), 135.57 (s), 138.61 (s), 146.93 (s), 158.30 (s),
170.83 (s) and 173.37 (s); m/z (FAB) 374.1758 (MHϩ.
C24H24NO3 requires m/z, 374.1756).
151.92 (s), 158.42 (s) and 175.31 (s); m/z (FAB) 529.2495 (MHϩ.
C35H33N2O3 requires m/z, 529.2491).
[4؉2] Adduct 4l. Colourless crystals; mp 191–192 ЊC (Found:
C, 75.58; H, 6.31; N, 4.63. C37H36N2O5 requires C, 75.49; H,
6.16; N, 4.76%); [α]D21 Ϫ47.8 (c 1.12 in CHCl3); νmax (KBr)/cmϪ1
3300 (NH), 1720 (C᎐O) and 1685 (C᎐O); δ (400 MHz; CDCl ;
[4؉2] Adduct 4h. Colourless crystals; mp 180–184 ЊC;
νmax (KBr)/cmϪ1 1740 (C᎐O), 1695 (C᎐O), 1520 (NO ) and 1360
᎐
᎐
2
(NO2); δH (270 MHz; CDCl3; Me4Si) 1.60 (3 H, d, J 7.0), 2.43
(3 H, s), 2.93 (1 H, d, J 7.0), 3.24 (1 H, d, J 7.0), 4.25 (1 H,
ddd, J 5.8, 1.5 and 1.5), 5.48 (1 H, q, J 7.0), 6.74 (1 H, dd,
J 8.1 and 5.8), 6.88 (1 H, dd, J 8.1 and 1.5), 7.13–7.30 (4 H, m),
7.48–7.55 (2 H, m) and 8.15–8.25 (2 H, m); δC (22.4 MHz;
CDCl3; Me4Si) 14.35 (q), 25.12 (q), 46.15 (d), 46.69 (d), 50.78
(s), 51.94 (d), 57.49 (d), 121.48 (d), 122.62 (d), 123.90 (d),
126.05 (d), 126.74 (d), 128.17 (d), 133.99 (d), 135.92 (d), 138.46
(s), 146.22 (s), 146.81 (s), 151.05 (s), 170.83 (s) and 172.86 (s);
m/z (FAB) 389.1499 (MHϩ. C23H21N2O4 requires m/z,
389.1451).
᎐
᎐
H
3
Me4Si) 1.59 (3 H, J 6.4), 1.62 (3 H, d, J 6.8), 2.98 (1 H, d, J 7.2),
3.02 (1 H, dd, J 7.2 and 1.5), 3.80 (3 H, s), 3.84 (6 H, s), 4.18
(1 H, ddd, J 5.9, 1.5 and 1.3), 5.47 (1 H, q, J 6.4), 5.91 (1 H, dq,
J 7.9 and 6.8), 6.54 (2 H, s), 6.72 (1 H, dd, J 8.1 and 5.9), 6.82
(1 H, dd, J 8.1 and 1.3), 7.18–7.58 (8 H, m), 7.75 (1 H, d, J 7.5),
7.85 (1 H, d, J 8.1), 8.15 (1 H, d, J 8.2), 8.58 (1 H, d, J 7.9);
δC (22.4 MHz; CDCl3; Me4Si) 14.73 (q), 22.10 (q), 45.58 (d),
46.36 (d), 47.70 (d), 51.34 (s), 52.42 (d), 56.18 (q), 57.76 (d),
60.77 (q), 104.30 (d), 121.75 (d), 122.14 (d), 122.35 (d), 123.04
(d), 125.33 (d), 125.60 (d), 125.81 (d), 126.26 (d), 126.50 (d),
127.93 (d), 128.82 (d), 130.70 (s), 133.90 (s), 134.28 (d), 135.30
(d), 136.94 (s), 138.70 (s), 139.06 (s), 139.24 (s), 146.99 (s),
151.86 (s), 153.29 (s) and 175.10 (s); m/z (FAB) 589.2684 (MHϩ.
C37H37N2O5 requires m/z, 589.2702).
[4؉2] Adduct 4i. Colourless solid; [α]2D1 Ϫ39.2 (c 1.05 in
CHCl3); νmax (KBr)/cmϪ1 3464 (NH), 1716 (C᎐O) and 1686
᎐
(C᎐O); δ (270 MHz; CDCl3; Me4Si) 1.56 (3 H, d, J 6.6), 1.63
᎐
H
(3 H, d, J 7.0), 2.99 (1 H, d, J 7.0), 3.10 (1 H, dd, J 7.0 and
1.5), 4.19 (1 H, ddd, J 5.4, 1.5 and 1.5), 5.45 (1 H, q, J 6.6),
5.90 (1 H, dq, J 7.7, 7.0), 6.68 (1 H, dd, J 7.7, 5.4), 6.75
(1 H, dd, J 7.7, 1.5), 7.15–7.55 (13 H, m), 7.71 (1H, d, J 7.7),
7.81 (1 H, dd, J 8.5 and 1.5), 8.13 (1 H, d, J 8.5) and 8.63
(1 H, d, J 7.7); δC (22.4 MHz; CDCl3; Me4Si) 14.65 (q), 22.13
(q), 45.58 (d), 46.06 (d), 47.40 (d), 51.28 (s), 52.42 (d), 57.70
(d), 121.72 (d), 122.14 (d), 122.35 (d), 123.01 (d), 125.33 (d),
125.57 (d), 125.72 (d), 126.23 (d), 126.44 (d), 126.74 (d),
127.15 (d), 127.90 (d), 128.79 (d), 130.64 (s), 133.87 (s),
134.40 (d), 135.09 (d), 138.82 (s), 139.06 (s), 143.47 (s),
147.08 (s), 151.86 (s) and 175.19 (s); m/z (EI) 498.2296 (Mϩ.
C34H30N2O2 requires M, 498.2309).
References
1 S. Speiser, Chem. Rev., 1996, 96, 1953; M. C. Jimenez, M. A.
Miranda and R. Tormos, J. Org. Chem., 1998, 63, 1323.
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6102.
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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; S. Kohmoto,
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4 T. R. Chamberlain and J. J. McCullough, Can. J. Chem., 1973, 51,
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and M. Sakamoto, J. Am. Chem. Soc., 1989, 111, 9254; K. Mizuno,
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1991, 2001; J. J. McCullough, T. B. McMurry and D. N. Work,
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and K. Mizuno, Org. Lett., 2000, 2, 3457.
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7660; Y. Kubo, M. Yoshioka, K. Kikuchi, S. Nakajima and
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S. Nakajima and I. Inamura, Tetrahedron Lett., 1999, 40, 2335.
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1901; H. Aoyama, Y. Arata and Y. Omote, J. Chem. Soc., Perkin
Trans. 1, 1986, 1165.
[4؉2] Adduct 4j. Colourless solid; [α]2D1 Ϫ40.7 (c 1.38 in
CHCl3); νmax (KBr)/cmϪ1 3310 (C᎐O) and 1715 (C᎐O); δ (400
᎐
᎐
H
MHz; CDCl3; Me4Si) 1.57 (3 H, d, J 6.6), 1.62 (3 H, d, J 7.0),
2.93 (1 H, d, J 7.2), 3.07 (1 H, dd, J 7.2 and 1.5), 4.18 (1 H, ddd,
J 5.9, 1.5 and 1.3), 5.46 (1 H, q, J 6.6), 5.90 (1 H, dq, J 7.9 and
7.0), 6.68 (1 H, dd, J 7.9 and 5.7), 6.81 (1 H, dd, J 7.9 and 1.3),
7.18–7.60 (12 H, m), 7.74 (1 H, d, J 7.5), 7.84 (1 H, d, J 8.4),
8.14 (1 H, d, J 8.2) and 8.57 (1 H, d, J 7.9); δC (22.4 MHz;
CDCl3; Me4Si) 14.62 (q), 22.07 (q), 45.44 (d), 45.55 (d), 47.20
(d), 51.22 (s), 52.42 (d), 57.70 (d), 121.75 (d), 122.11 (d), 122.35
(d), 122.98 (d), 125.30 (d), 125.57 (d), 125.84 (d), 126.23 (d),
126.50 (d), 127.90 (d), 128.53 (d), 128.73 (d), 130.61 (s), 132.52
(s), 133.87 (s), 134.04 (d), 135.45 (d), 138.61 (s), 139.00 (s),
141.95 (s), 146.75 (s), 151.74 (s) and 174.92 (s); m/z (FAB)
533.1987 (MHϩ. C34H3035ClN2O2 requires m/z, 533.1996).
[4؉2] Adduct 4k. Colourless solid; [α]2D1 Ϫ40.4 (c 0.86 in
CHCl3); νmax (KBr)/cmϪ1 3310 (NH), 1715 (C᎐O) and 1615 (C᎐
᎐
᎐
O); δH (400 MHz; CDCl3; Me4Si) 1.57 (3 H, d, J 7.0), 1.61 (3 H,
d, J 7.0), 2.96 (1 H, d, J 7.0), 3.06 (1 H, dd, J 7.0 and 1.5), 3.78
(3 H, s), 4.18 (1 H, dd, J 5.8 and 1.5), 5.45 (1 H, q, J 7.0), 5.90
(1 H, dq, J 7.0 and 7.0), 6.70 (1 H, dd, J 8.5 and 5.9), 6.78 (1 H,
dd, J 8.1 and 1.5), 6.83 (2H, m), 7.20–7.60 (10H, m), 7.73 (1 H,
d, J 7.7), 7.83 (1 H, d, J 8.5), 8.13 (1 H, d, J 8.5) and 8.62 (1 H,
d, J 7.7); δC (22.4 MHz; CDCl3; Me4Si) 14.68 (q), 22.13 (q),
45.35 (d), 45.58 (d), 47.79 (d), 51.28 (s), 52.45 (d), 55.25 (q),
57.85 (d), 114.09 (d), 121.72 (d), 122.17 (d), 122.35 (d), 123.04
(d), 125.36 (d), 125.60 (d), 125.72 (d), 126.26 (d), 126.44 (d),
127.90 (d), 128.14 (d), 128.82 (d), 130.67 (s), 133.93 (s), 134.43
(s), 135.12 (s), 135.66 (s), 138.76 (d), 139.12 (d), 147.20 (s),
7 E. A. Chandross and C. J. Dempster, J. Am. Chem. Soc., 1970, 92,
704.
8 S. Kohmoto, T. Kreher, Y. Miyaji, M. Yamamoto and K. Yamada,
J. Org. Chem., 1992, 57, 3490.
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1977, 33, 485.
10 H.-D. Scharf, H. Leismann, W. Frb, H. W. Gaidetzka and J. Aretz,
Pure Appl. Chem., 1975, 41, 581.
11 H. R. Memarian, M. Nasr-Esfahani, R. Boese and D. Döpp, Liebigs
Ann./Recl., 1997, 1023.
12 K. Kishikawa, M. Yamamoto, S. Kohmoto and K. Yamada, J. Org.
Chem., 1989, 54, 2428.
2088
J. Chem. Soc., Perkin Trans. 1, 2001, 2082–2088