Highly selective conversion of N-aroyl-α-dehydronaphthylalaninamides into 3,4-dihydrobenzoquinolinone derivatives via photoinduced intermolecular electron transfer

Article abstract of DOI:10.1016/j.tet.2004.08.096

The irradiation of substituted (Z)-N-aroyl-α- dehydronaphthylalaninamides [(Z)-1] in methanol containing triethylamine (TEA) with Pyrex-filtered light was found to give 3,4-dihydrobenzoquinolinone derivatives (2) in high yields along with minor amounts of 4,5-dihydrooxazole derivatives (3). Analysis of the substituent effects on product composition revealed that both the photoreactivity of 1 and the selectivity of 2 are decreased with increasing electron-withdrawing ability of the substituent introduced at the para-position on the N-benzoyl benzene ring. From the analysis of the dependence of the quantum yield for the formation of 2 on the TEA concentration, it was found that back electron transfer occurs efficiently within an (E)-1 anion radical-TEA cation radical pair intermediate. Graphical Abstract

Full text of DOI:10.1016/j.tet.2004.08.096

Tetrahedron 60 (2004) 10293–10304
Highly selective conversion of
N-aroyl-a-dehydronaphthylalaninamides into
3,4-dihydrobenzoquinolinone derivatives via photoinduced
intermolecular electron transfer
*
Kei Maekawa, Ayana Shinozuka, Michiko Naito, Tetsutaro Igarashi and Tadamitsu Sakurai
*
Department of Applied Chemistry, Faculty of Engineering, Kanagawa University, Kanagawa-ku, Yokohama 221-8686, Japan
Received 30 June 2004; accepted 23 August 2004
Abstract—The irradiation of substituted (Z)-N-aroyl-a-dehydronaphthylalaninamides [(Z)-1] in methanol containing triethylamine (TEA)
with Pyrex-filtered light was found to give 3,4-dihydrobenzoquinolinone derivatives (2) in high yields along with minor amounts of
4,5-dihydrooxazole derivatives (3). Analysis of the substituent effects on product composition revealed that both the photoreactivity of 1 and
the selectivity of 2 are decreased with increasing electron-withdrawing ability of the substituent introduced at the para-position on the
N-benzoyl benzene ring. From the analysis of the dependence of the quantum yield for the formation of 2 on the TEA concentration, it was
found that back electron transfer occurs efficiently within an (E)-1 anion radical–TEA cation radical pair intermediate.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
study we discovered a novel intermolecular ET-initiated
photocyclization reaction of substituted N-acetyl-a-dehy-
dronaphthylalaninamides that afford 3,4-dihydrobenzo[f]-
quinolinones.6 Because many heterocyclic compounds
having a dihydroquinolinone ring exhibit pharmacological
and physiological activities, it is of fundamental signifi-
cance to develop synthetic methods for the construction of
the quinolinone ring.8 If we consider that PET reactions of
Organic photochemistry has continued to contribute to the
development of efficient and selective transformations for
the preparation of complicated molecules which could not
have been synthesized by conventional methods. In recent
years much attention is being devoted to the synthetic
application of photoinduced electron transfer (PET) reac-
tions, owing to the fact that many of these reactions enable
the construction of various heterocyclic rings.1 On the other
hand, a-dehydroamino acid derivative is one of the
important intermediates for the synthesis of natural and
biologically active products. Many useful synthetic methods
of substituted a-dehydroamino acid derivatives have been
reported but there have been only limited investigations of
the photochemistry of these amino acid derivatives.2,3
Taking into account the fact that aromatic olefins undergo
efficient PET reactions in their excited states,4 it can be
expected that a-dehydroamino acids having the aromatic
olefin chromophore are subject to PET reactions. Keeping
this expectation in mind, we embarked on a systematic study
toward the characterization of the excited-state reactivity of
substituted a-dehydroamino acids.5–7 In the course of this
Keywords: Amino acids and derivatives; Photochemistry; Electron transfer;
Photocyclization; Dihydrobenzoquinolinones.
N-aroyl-a-dehydronaphthylalaninamides may afford the
corresponding dihydrobenzoquinolinone derivatives in
high selectivities, it is possible to extend synthetic utility
of the ET-initiated photocyclization reactions described
* Corresponding authors. Tel.: C81 45 481 5661; fax: C81 45 491 7915;
e-mail addresses: maekako2@kanagawa-u.ac.jp;
sakurt01@kanagawa-u.ac.jp
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.08.096

10294
K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
above. For this end we synthesized (Z)-N-aroyl-a-dehydro-
naphthylalaninamides [(Z)-1a–l] and investigated substitu-
ent effects on both the reactivity of (Z)-1 and the selectivity
of each photoproduct. Additionally, we analyzed quantum
yield for the photoisomerization of (E)-1 as well as the
effects of TEA concentration on the quantum yield for the
formation of dihydrobenzoquinolinone derivative, hoping to
shed much light on the mechanism of novel ET-initiated
photocyclization reactions.
distribution was obtained by the irradiation of other
a-dehydro(1-naphthyl)alaninamide derivatives (1b–i).
The finding that the photoproducts (2a and 3a) are stable
enough such that they undergo only negligible decompo-
sition under the irradiation conditions employed (450 W
high-pressure Hg lamp; Pyrex-filtered light; [(Z)-1a]Z
3.75!10K3 mol dmK3; [TEA]Z0.10 mol dmK3) made it
1
possible to monitor the reactions by means of H NMR
spectroscopy, as typically shown in Table 1. The result
obtained for (Z)-1a demonstrates the rapid production of
(E)-1a and the subsequent increase in compositions for 2a
and 3a with the decrease of (E)- and (Z)-isomer compo-
sitions, being consistent with the mechanism in which the
excited-state (E)- and (Z)-isomers serve as precursors of
these products. Based on our previous findings,6,7 we are
able to propose Scheme 2 as the formation mechanism of
dihydrobenzoquinolinone (2) and dihydrooxazole deriva-
tives (3). The result that at the early stage of the reaction
(0.5-h irradiation) the composition ratio of (Z)-1a to its
isomer exhibits a negligible dependence on the TEA
concentration (0–0.10 mol dmK3) strongly suggests a
minor contribution of the isomerization from (Z)-1aK% to
its isomer anion radical, (E)-1aK%. It is, thus, very likely that
the (Z)-1-derived ion radical pair (Z)-IA undergoes an
exclusive back ET to regenerate (Z)-1 and TEA (Scheme 2).
An ET from the ground-state TEA to the singlet excited-
state (E)-isomer produces the ion radical pair intermediate
(E)-IA which may be in equilibrium with the ion radical pair
(E)-IB formed via intramolecular ET. Hydrogen transfer
from the amide nitrogen to the amide carbonyl oxygen in the
intermediate (E)-IA and the subsequent back ET to the TEA
cation radical afford TEA and the enol-type biradical
intermediate II, the coupling and tautomerization of which
generate the cyclization product III. The process that
reaches the dihydrobenzoquinolinone derivative (2) is
completed by aromatization of III via hydrogen shift. In
competition with this cyclization process, the nucleophilic
attack of the N-acyl carbonyl oxygen anion upon the olefinic
carbon in (E)-IB takes place to give the cyclized anion
radical. A back ET to the TEA cation radical followed by
2. Results and discussion
2.1. Photocyclization of (Z)-1a–l
The starting (Z)-isomers (1a–l) were prepared in good yields
by the ring-opening reactions of (Z)-naphthyl-substituted
oxazolones with primary amines.9 After a nitrogen-
saturated methanol solution of (Z)-1a (3.75!10K3
mol dmK3) containing TEA (0.10 mol dmK3) was irra-
diated with Pyrex-filtered light (O280 nm) from a 400 W
high-pressure Hg lamp for 3 h at room temperature, the
product mixture obtained was washed with a small amount
of EtOH and then with hexane, giving the analytically pure
3,4-dihydrobenzo[f]quinolinone derivative (2a, 67%; con-
version, O99%). Preparative TLC (silica gel) of the residual
solid [that was obtained by evaporating the filtrate (EtOH–
hexane) to dryness] enabled the isolation of the cis-4,5-
dihydrooxazole derivative (cis-3a, 5%). In addition, we
succeeded in isolating the (E)-isomer from the reaction
mixture obtained by the 0.5-h irradiation of (Z)-1a
(conversion, 7%; Scheme 1). The structures of isolated
products were determined based on their spectroscopic and
physical properties and were confirmed by the H–1H and
1
13C–1H COSY spectra of these products. Careful H NMR
1
spectral analysis of the product mixture suggested that there
is very little formation of the trans-4,5-dihydrooxazole
derivative (trans-3a) whose ring-proton signals with the J4,5
value of 6.4 Hz were detected at 4.75 and 6.57 ppm,7 though
attempts to isolate trans-3a from the mixture were
unsuccessful owing to its poor yield. The same product
Scheme 1.
Table 1. Relation between irradiation time and composition (%) of each compound obtained by the 5-h irradiation of (Z)-1a in MeOH–TEA at room
temperature
Irradiation time (h)
Composition (%)
(Z)-1a
(E)-1a
2a
cis-3a
trans-3a
0
100
85.6
52.8
36.1
0
12.8
25.3
20.5
0
1.4
19.7
39.3
0
0.2
1.9
3.5
0
0
0.3
0.6
0.5
3.0
5.0

K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
10295
Scheme 2.
hydrogen shift leads to cis- and trans-3 (Scheme 2).
Evidence in support of this mechanism comes from the
finding that the free energy change (DGet) for an ET from
(0.10 mol dmK3) at room temperature (450 W high-pres-
sure Hg lamp; Pyrex-filtered light). An inspection of Table 2
demonstrates that the reactivity of 1 has a clear propensity to
decrease with increasing the electron-withdrawing ability of
the substituent introduced at the para-position on the
benzoyl benzene ring (1bO1az1cO1d[1e). It is likely
that anion radical produced by an ET from TEA migrates to
the benzoyl moiety in the presence of stronger electron-
withdrawing substituent to a more extent. Therefore, we see
that the introduction of trifluoromethyl or cyano group
promotes a back ET from the anion radical to the TEA
cation radical to result in a decrease in the conversion of 1.
Additionally, the observation that the selectivity of 2 is also
decreased by introducing these substituents allows us to
propose that the shift of equilibrium between (E)-IA and
(E)-IB to the latter intermediate lowers the relative rate for
hydrogen abstraction in the former intermediate (Scheme 2).
Taking into account the fact that the irradiation of 1b having
the electron-donating methoxy substituent at the para-
position on the benzoyl benzene ring gives 2 in higher
selectivity than that of 1a, it can be predicted that the
conversion of 1 and the selectivity of 2 is enhanced with
decreasing the electron-withdrawing ability of aroyl group.
From the data given in Table 2 we can see that the
conversion of 1g having the trimethylacetyl group is higher
than that of 1a having the benzoyl and also that the
selectivity of 2g is greater as compared to that of 2a.
TEA to the singlet excited-state (E)-1f is K85 kJ molK1
.
This DGet was estimated by using the simplified Weller
equation: DGet/kJ molK1Z96.5 (EoxKEred)KES,10 where
Eox, Ered and ES refer to the oxidation potential of TEA
(0.76 V vs. Ag/AgCl in MeCN), the reduction potential of
(E)-1f (K2.09 V vs. Ag/AgCl in MeCN) and the first singlet
excitation energy of (E)-1f (360 kJ molK1 in MeCN),
respectively. In addition, a methanol solution of 1a
(3.75!10K3 mol dmK3) containing deuteriated TEA
(0.10 mol dmK3) was irradiated with Pyrex-filtered light
from a 450 W high pressure Hg lamp for 3.0 h at room
temperature. 1H NMR spectral analysis of the product
mixture in DMSO-d6, obtained after usual work-up, clearly
showed no disappearance of the 4.86 ppm signal which is
ascribed to the proton attached to the 3-position of the
dihydrobenzoquinolinone ring. This finding substantiates
that proton transfer from the TEA cation radical to the
(E)-1-derived anion radical occurs within the intermediate
(E)-IA to, if any, only a small extent and, hence, consistent
with the formation mechanism shown in Scheme 2.
In Table 2 is summarized composition of each compound
obtained by the 0.5- and 5-h irradiation of methanol
solutions of 1a–i (3.75!10K3 mol dmK3) containing TEA

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K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
Table 2. Substituent effects on the conversion of 1 and selectivity of each compound, obtained by the irradiation of (Z)-1 in MeOH containing TEA at room
temperature
Compound
Irradiation time
(h)
Composition (%)
Conversiona
(%)
Selectivity of 2
(%)b
(Z)-1
(E)-1
2
3c
1a
1b
1c
1d
1e
1f
0.5
5
85.6
36.1
12.8
20.5
1.4
39.3
0.2
4.1
43
78
38
23
15
44
62
36
35
91
97
90
82
74
100
97
76
81
0.5
5
78.9
14.8
16.7
7.4
4.4
75.6
0
2.2
0.5
5
87.0
40.0
11.6
21.8
1.3
34.2
0.2
3.9
0.5
5
93.2
51.6
6.8
25.5
0
18.8
0
4.1
0.5
10
97.9
60.1
2.1
25.0
0
11.1
0
3.8
0.5
5
86.9
48.8
9.4
7.4
3.6
43.8
0
0
1g
1h
1i
0.5
5
79.3
21.6
18.2
16.9
2.5
59.9
0
1.6
0.5
5
82.4
37.8
16.0
26.2
1.1
27.3
0.5
8.7
0.5
5
82.7
36.4
16.0
28.2
0.6
28.6
0.4
6.7
a
Conversion was estimated by the sum of compostion for 2 and 3.
Selectivity for 2 was evaluated by dividing the composition for 2 by the sum of compostion for 2 and 3.
The sum of composition for cis-3 and trans-3.
b
c
Interestingly, ET-initiated photocyclization of 1f bearing
the 2,4-dimethoxybenzoyl group afforded 2f in quantitative
yield without forming 3f, though the expected high
conversion of 1f was not attained. Because the rate for
isomerization of (Z)-1f is much slower as compared to that
of (Z)-1b (Table 2, 0.5-h irradiation), it is reasonable to
explain the decreased photoreactivity of 2,4-dimethoxyben-
zoyl-substituted 1f in terms of the enhanced deactivation of
the excited-state (Z)-1f. Electronic effects of the ortho-
methoxy group in the (Z)-isomer may play a role in slowing
Table 3. Composition of each compound, conversion of 1 and selectivity of 2, obtained by the 5-h irradiation of (Z)-1 in MeOH containing DBU at room
temperature
Compound
Composition (%)
Conversion (%)
Selectivity of 2
(%)
(Z)-1
(E)-1
2
3a
1j
1k
1l
48.1
53.8
62.8
27.1
15.2
19.1
17.6
25.7
11.4
7.2
5.3
6.7
25
31
18
71
83
63
a
The mixture of cis- and trans-isomers.

K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
10297
down the isomerization into (E)-1f. These considerations,
therefore, substantiate the mechanism proposed by us.
less than 4% conversion of (E)-1f employed as the starting
isomer. By applying the steady-state approximation to
Scheme 3, we obtain Eqs. 1 and 2, where F2f and Fi refer to
the quantum yields for the formation of 2f and for the
isomerization, respectively.
In order to explore the scope and limitations of the observed
ET-initiated photocyclization, we attempted PET reactions
of a-dehydronaphthylalaninamides (1j–l) in which the
2-naphthyl group was introduced instead of the 1-naphthyl.
ꢀ
ꢁꢂ
ꢃ
kKet
k2f
kd Cki
FK2f1 Z 1 C
1 C
(1)
(2)
When a methanol solution of 1j (3.75!10K3 mol dmK3
)
ket½TEAꢀ
containing TEA (0.10 mol dmK3) was irradiated with
Pyrex-filtered light from a 450 W high-pressure Hg lamp
at room temperature, complicated product mixtures were
obtained. However, the use of 1,8-diazabicyclo[5.4.0]un-
dec-7-ene (DBU, 0.10 mol dmK3) as an electron donor
enabled the estimation of composition for each compound
obtained by the 5-h irradiation of 1j, as shown in Table 3.
Because DBU possesses greater electron-donating ability
than TEA, the presence of DBU is considered to markedly
enhance the relative rate of ET process affording only the
products derived from PET reaction. The same product
distribution was observed by the irradiation of methanol
solutions of 1k and 1l (Table 3). A comparison of the
selectivity for 2a,b,f with that for 2j–l reveals that
replacement of the 1-naphthyl group by the 2-naphthyl
lowers the selectivity of a given dihydrobenzoquinolinone.
The 2-naphthyl substituent in (E)-1j–l is considered to exert
less steric hindrance than the 1-naphthyl in (E)-1a–i in the
cyclization process from the anion radical in IB. This less
steric hindrance accelerates the cyclization reaction that
proceeds through IB to result in a decrease in the selectivity
of 2 as observed.
ki
Fi Z
ðki CkdÞ
As typically depicted in Figure 1, there was a linear
relationship between the reciprocals of F2f (FK2f 1) and TEA
concentration ([TEA]K1). From the intercept and the ratio
of slope to the intercept of linear plot obtained, we were able
to evaluate the relative rates of ET and back ET processes,
that is, the magnitude of ket/(kdCki) and kKet/k2f, respec-
2.2. Effects of TEA concentration on the quantum yield
for formation of 2
As described in Section 2.1, the ET-initiated photocycliza-
tion of 1f selectively produces the corresponding dihydro-
benzoquinolinone derivative (2f). This result allows us to
obtain quantitative information concerning the relative rates
of ET and related processes (that control the formation
efficiency of 2), through analysis of the TEA concentration
dependence of the quantum yield (F) for appearance of 2.
We are able to propose Scheme 3 based on the findings that
the presence of TEA affects the rate for photoisomerization
from (E)-1 into (Z)-1 to a negligible extent and, in addition,
the singlet excited-state (E)-isomer serves as a precursor of
2. In order to exclude the contribution of (Z)-1f-derived ET
reaction process, quantum yields for the isomerization into
(Z)-1f as well as for appearance of 2f were determined at
K1
2f
Figure 1. Double reciprocal plot of F
versus [TEA]K1 for the
ET-initiated photocyclization of (E)-1f in methanol at room temperature.
tively. Furthermore, there was no formation of 2f when a
methanol solution of (E)-1f containing no TEA was
irradiated,6 so that we were able to determine quantum
yield for the isomerization (Fi) and then to estimate the
relative rates of given processes by the use of Fi (Z0.35G
0.01) and Eqs. 3–5.
ket
ket
Z
(3)
(4)
(5)
Fiðkd CkiÞ ki
kd
FKi 1 K1 Z
ki
ꢀ
ꢁꢀ
ꢁ
ket
ki
ki
ket
kd
Z
kd
In Table 4 are summarized these relative rates which
demonstrate that the ET rate (ket[TEA], [TEA]Z
0.10 mol dmK3) is faster than the rate for deactivation and
isomerization (kdCki) of the excited-state (E)-1f by a factor
of about 2. In addition, the magnitude of ki/kd confirms that
isomerization into (Z)-1f is the minor deactivation pathway
of the excited-state (E)-isomer in the absence of TEA.
Despite the rapid progress of PET reaction, the F2f value
Scheme 3.

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K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
Table 4. Relative rates for given processes
ket[TEA]/(kdCki)a
1.9
kKet/k2f
a
ki/kd
ket[TEA]/kd
ket[TEA]/kia
0.54
2.9
5.4
14
a
Value estimated at [TEA]Z0.10 mol dmK3
.
was not so large (F2fZ0.045 at [TEA]Z0.10 mol dmK3).
The fact that the rate for a back ET from the (E)-1 anion
radical to the TEA cation radical (kKet) is 14 times as fast as
that for the cyclization (k2f), therefore, led us to conclude
that the relative rate for this back ET is a major factor that
controls the overall efficiency of PET reactions examined.
employed to determine quantum yields for appearance of
2f and (Z)-1f at low conversions of the starting (E)-1f (!
4%).13 A 450 W high-pressure Hg lamp was used as the
light source from which 313 nm light was selected with
1.0 wt% potassium carbonate solution of potassium chro-
mate (2.0!10K3 mol dmK3), CORNING 7-54 and
TOSHIBA IRA-25S glass filters. Linear calibration curves
for 2f and (Z)-1f, made under the same analytical
conditions, were utilized to quantify the formation of
these two compounds. All of the quantum yields are an
average of more than three determinations.
3. Conclusions
Although there are many synthetic methods for the construc-
tion of significant heterocyclic rings,11 convenient photo-
chemical route to dihydrobenzoquinolinone derivatives is
scarcely known.12 Because itis faciletoprepare the starting N-
aroyl-a-dehydronaphthylalaninamides (1) and related a-
dehydroarylalaninamides, a wide variety of substituted
dihydroquinolinones can be synthesized by the ET-initiated
photocyclization of these alaninamide derivatives. The facts
that dihydrobenzoquinolinones are extremely stable under
irradiation conditions and then obtained in high selectivities
renderour PET reactions inmethanolcontainingTEA orDBU
very useful in constructing the dihydroquinolinone ring. We
were also able to obtain quantitative information about the
relative rates of ET and related processes, through analysis of
the dependence of quantum yield for formation of 2 on the
TEA concentration.
4.2. General procedure for the synthesis of (Z)-4-
(1-naphthylmethylene)-2-(substituted phenyl)-5(4H)-
oxazolones, (Z)-4-(2-naphthylmethylene)-2-(substituted
phenyl)-5(4H)-oxazolones and (Z)-2-(tert-butyl)-4-
(1-naphthylmethylene)-5(4H)-oxazolone
N-(Substituted benzoyl)glycine or trimethylacetylglycine
(0.04 mol), 1-naphthaldehyde or 2-naphthaldehyde (0.05 mol),
and sodium acetate (0.02 mol) were added to acetic anhydride
(25 mL) and the resulting mixture was heated at 65–75 8C for
1–2 h [N-(substituted benzoyl)glycine] or 6 h (N-trimethyl-
acetylglycine) with stirring. The mixture was cooled with ice
and the solid separated out was collected by filtration with
suction and washed with water, a small amount of cold EtOH
andthenwithdryhexane. Afterthecrudeproducthadbeenair-
dried at room temperature, it was recrystallized from hexane–
CHCl3 to give yellow crystals (50–70%).
4. Experimental
4.1. General
4.2.1. (Z)-2-Phenyl-4-(1-naphthylmethylene)-5(4H)-oxa-
zolone. Mp 166.0–167.0 8C. IR (KBr): 1797, 1647,
1
1167 cmK1. H NMR (500 MHz, CDCl3): d 7.54 (2H, dd,
1H and 13C NMR and IR spectra were taken with a JEOL
JNM-A500 spectrometer and a HITACHI 270-30 infrared
spectrometer, respectively. Chemical shifts were deter-
mined using tetramethylsilane as an internal standard.
HPLC analysis was performed on a SHIMADZU LC-
10AT high-performance liquid chromatography system
equipped with a 4.6!250-mm ODS (Zorbax) column and
a SHIMADZU SPD-10A UV detector (detection wave-
lengthZ240 nm; mobile phase, MeCN/H2OZ60:40, v/v).
UV absorption and fluorescence spectra were measured at
room temperature with a HITACHI U-3300 spectro-
photometer and a HITACHI F-4500 spectrofluorimeter,
respectively. A cell with a 10-mm pathlength was used.
Elemental analysis was performed on a PERKIN–ELMER
PE2400 series II CHNS/O analyzer. Oxidation and
reduction potentials were measured with a YANACO
P-1100 polarographic analyzer. Mass spectra were recorded
on a JEOL JMS-01SG-2 spectrometer. MeOH was purified
according to the standard procedure and freshly distilled
prior to use. TEA and DBU were fractionally distilled from
sodium hydroxide. All other reagents used were obtained
from commercial sources and of the highest grade available.
JZ7.3, 7.6 Hz), 7.55 (1H, dd, JZ8.6, 8.6 Hz), 7.62 (1H, dd,
JZ7.3, 7.3 Hz), 7.63 (1H, dd, JZ8.6, 8.6 Hz), 7.64 (1H, dd,
JZ6.7, 8.6 Hz), 7.90 (1H, d, JZ8.6 Hz), 7.97 (1H, d, JZ
8.6 Hz), 8.13 (1H, s), 8.21 (2H, d, JZ7.6 Hz), 8.31 (1H, d,
JZ8.6 Hz), 9.03 (1H, d, JZ6.7 Hz).
4.2.2. (Z)-2-(4-Methoxyphenyl)-4-(1-naphthylmethyl-
ene)-5(4H)-oxazolone. Mp 207.0–208.0 8C. IR (KBr):
1
1788, 1644, 1170 cmK1. H NMR (500 MHz, CDCl3): d
3.91 (3H, s), 7.03 (2H, d, JZ8.8 Hz), 7.54–7.66 (3H, m),
7.90 (1H, d, JZ7.9 Hz), 7.95 (1H, d, JZ7.9 Hz), 8.07 (1H,
s), 8.16 (2H, d, JZ8.8 Hz), 8.32 (1H, d, JZ8.5 Hz), 9.02
(1H, d, JZ7.3 Hz).
4.2.3. (Z)-2-(4-Bromophenyl)-4-(1-naphthylmethylene)-
5(4H)-oxazolone. Mp 201.0–201.5 8C. IR (KBr): 1799,
1650, 1180 cmK1. 1H NMR (500 MHz, CDCl3): d 7.57 (1H,
dd, JZ7.6, 7.6 Hz), 7.63–7.66 (2H, m), 7.69 (2H, d, JZ
8.3 Hz), 7.92 (1H, d, JZ8.2 Hz), 7.99 (1H, d, JZ8.3 Hz),
8.07 (2H, d, JZ8.3 Hz), 8.17 (1H, s), 8.31 (1H, d, JZ
8.2 Hz), 9.00 (1H, d, JZ7.6 Hz).
4.2.4. (Z)-2-(4-Trifluoromethylphenyl)-4-(1-naphthyl-
methylene)-5(4H)-oxazolone. Mp 201.0–202.0 8C. IR
A potassium tris(oxalato)ferrate(III) actinometer was

K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
10299
(KBr): 1797, 1641, 1167 cmK1
.
1H NMR (500 MHz,
5(4H)-oxazolone (for 1a–f,h,i, 0.010 mol), (Z)-2-(tert-
butyl)-4-(1-naphthylmethylene)-5(4H)-oxazolone (for 1g,
0.010 mol) or (Z)-4-(2-naphthylmethylene)-2-(substituted
phenyl)-5(4H)-oxazolone (for 1j–l, 0.010 mol) was added
to dry CHCl3 (30 mL) containing primary amine
(0.012 mol) and the resulting solution was stirred for
0.5–1 h at room temperature. After removal of the solvent
under reduced pressure, the crystalline solid obtained was
recrystallized twice from EtOH–hexane affording colorless
crystals (50–80%).
CDCl3): d 7.58 (1H, dd, JZ6.7, 7.9 Hz), 7.65–7.69 (2H,
m), 7.81 (2H, d, JZ8.6 Hz), 7.93 (1H, d, JZ8.2 Hz), 8.10
(1H, d, JZ8.2 Hz), 8.24 (1H, s), 8.33 (2H, d, JZ8.6 Hz),
8.33 (1H, d, JZ7.9 Hz), 9.02 (1H, d, JZ7.6 Hz).
4.2.5. (Z)-2-(4-Cyanophenyl)-4-(1-naphthylmethylene)-
5(4H)-oxazolone. Mp 237.0–238.0 8C. IR (KBr): 2236,
1
1794, 1641, 1164 cmK1. H NMR (500 MHz, CDCl3): d
7.59 (1H, dd, JZ7.3, 7.9 Hz), 7.64–7.68 (2H, m), 7.84 (2H,
d, JZ8.2 Hz), 7.93 (1H, d, JZ7.9 Hz), 8.02 (1H, d, JZ
7.9 Hz), 8.25 (1H, s), 8.31 (2H, d, JZ8.2 Hz), 8.32 (1H, d,
JZ8.5 Hz), 9.00 (1H, d, JZ7.3 Hz).
4.3.1. (Z)-2-Benzoylamino-N-methyl-3-(1-naphthyl)-2-
propenamide [(Z)-1a]. Mp 205.0–206.0 8C. IR (KBr):
1650, 1670, 3080, 3300 cmK1 1H NMR (500 MHz,
.
4.2.6. (Z)-2-(2,4-Dimethoxyphenyl)-4-(1-naphthylmethyl-
ene)-5(4H)-oxazolone. Mp 174.0–175.5 8C. IR (KBr):
DMSO-d6): d 2.75 (3H, d, JZ4.9 Hz) 7.43 (2H, dd, JZ
7.3, 7.3 Hz), 7.43 (1H, dd, JZ6.7, 7.9 Hz), 7.52 (1H, dd,
JZ7.3, 7.3 Hz), 7.54 (1H, dd, JZ6.7, 7.0 Hz), 7.56 (1H, dd,
JZ6.7, 7.9 Hz), 7.62 (1H, d, JZ6.7 Hz), 7.76 (1H, s), 7.84
(2H, d, JZ7.3 Hz), 7.86 (1H, d, JZ7.9 Hz), 7.93 (1H, d,
JZ7.0 Hz), 8.04 (1H, d, JZ7.9 Hz), 8.19 (1H, q, JZ
4.9 Hz), 9.75 (1H, s). 13C NMR (125 MHz, DMSO-d6): d
26.3, 124.2, 125.3, 125.99, 126.02, 126.03, 126.3, 127.8
(2C), 128.0 (2C), 128.4 (2C), 131.1, 131.5 (2C), 132.4,
133.1, 133.7, 165.2, 166.2. Anal. Calcd (found) for
C21H18N2O2: C, 76.34 (75.97); H, 5.49 (5.18); N, 8.48%
(8.45%).
1
1768, 1643, 1165 cmK1. H NMR (500 MHz, CDCl3): d
3.91 (3H, s), 4.01 (3H, s), 6.56 (1H, d, JZ2.4 Hz), 6.63 (1H,
dd, JZ2.4, 8.5 Hz), 7.55 (1H, dd, JZ7.3, 6.7 Hz), 7.6–7.60
(2H, m), 7.89 (1H, d, JZ7.9 Hz), 7.94 (1H, d, JZ8.5 Hz),
8.05 (1H, s), 8.08 (1H, d, JZ8.5 Hz), 8.33 (1H, d, JZ
8.5 Hz), 9.07 (1H, d, JZ7.3 Hz).
4.2.7. (Z)-2-(tert-Butyl)-4-(1-naphthylmethylene)-5(4H)-
oxazolone. Mp 89.0–90.0 8C. IR (KBr): 1794, 1652, 1647,
1
1150 cmK1. H NMR (500 MHz, CDCl3): d 1.41 (9H, s),
7.54 (1H, dd, JZ6.9, 8.2 Hz), 7.60 (1H, dd, JZ7.6, 8.2 Hz),
7.61 (1H, dd, JZ6.9, 8.9 Hz), 7.89 (1H, d, JZ8.2 Hz), 7.94
(1H, d, JZ8.2 Hz), 8.04 (1H, s), 8.27 (1H, d, JZ8.9 Hz),
8.89 (1H, d, JZ7.6 Hz).
4.3.2. (Z)-2-(4-Anisoylamino)-N-methyl-3-(1-naphthyl)-
2-propenamide [(Z)-1b]. Mp 226.0–227.0 8C. IR (KBr):
1670, 1650, 3080, 3300 cmK1 1H NMR (500 MHz,
.
DMSO-d6): d 2.74 (3H, d, JZ4.3 Hz), 3.79 (3H, s), 6.96
(2H, d, JZ8.6 Hz), 7.42 (1H, dd, JZ7.3, 7.9 Hz), 7.57–7.53
(2H, m), 7.60 (1H, d, JZ7.3 Hz), 7.71 (1H, s), 7.83 (2H, d,
JZ8.6 Hz), 7.85 (1H, d, JZ7.9 Hz), 7.93 (1H, d, JZ
7.6 Hz), 8.03 (1H, d, JZ7.9 Hz), 8.16 (1H, q, JZ4.3 Hz),
9.61 (1H, s). 13C NMR (125 MHz, DMSO-d6): d 26.3, 55.4,
113.3 (2C), 124.3, 125.4, 125.5, 126.0 (2C), 126.03, 126.4,
128.38, 128.40, 129.8 (2C), 131.2 (2C), 131.5, 132.6, 161.9,
165.4, 165.7. Anal. Calcd (found) for C22H20N2O3: C, 73.32
(73.53); H, 5.59 (5.51); N, 7.77% (7.37%).
4.2.8. (Z)-4-(2-Naphthylmethylene)-2-phenyl-5(4H)-oxa-
zolone. Mp142.0–143.0 8C. IR (KBr): 1797, 1626, 1167 cmK1
.
1H NMR (500 MHz, CDCl3): d 7.51 (1H, dd, JZ7.9, 7.9 Hz),
7.54 (1H, dd, JZ7.9, 7.9 Hz), 7.54 (2H, dd, JZ7.9, 7.9 Hz),
7.61 (1H, dd, JZ7.9, 7.9 Hz), 7.83 (1H, d, JZ7.9 Hz), 7.89
(1H, d, JZ8.5 Hz), 7.91 (1H, d, JZ7.9 Hz), 8.19 (2H, d, JZ
7.9 Hz), 8.43 (1H, s), 8.49 (1H, d, JZ8.5 Hz).
4.2.9. (Z)-2-(4-Methoxyphenyl)-4-(2-naphthylmethyl-
ene)-5(4H)-oxazolone. Mp 198.0–199.0 8C. IR (KBr):
1
1788, 1653, 1167 cmK1. H NMR (500 MHz, CDCl3): d
4.3.3. (Z)-2-(4-Bromobenzoylamino)-N-methyl-3-(1-
naphthyl)-2-propenamide [(Z)-1c]. Mp 220.0–221.0 8C.
3.91 (3H, s), 7.04 (2H, d, JZ8.9 Hz), 7.32 (1H, s), 7.49–
7.58 (2H, m), 7.83–7.94 (3H, m), 8.17 (2H, d, JZ8.9 Hz),
8.46–8.52 (2H, m).
IR (KBr): 1630, 1650, 3200, 3350 cmK1 1H NMR
.
(500 MHz, DMSO-d6): d 2.74 (3H, d, JZ4.9 Hz), 7.43
(1H, dd, JZ7.3, 7.9 Hz), 7.56–7.52 (2H, m), 7.58 (1H, d,
JZ7.3 Hz), 7.66 (2H, d, JZ8.6 Hz), 7.76 (1H, s), 7.78 (2H,
d, JZ8.6 Hz), 7.86 (1H, d, JZ7.9 Hz), 7.93 (1H, d, JZ
9.2 Hz), 8.02 (1H, d, JZ7.3 Hz), 8.22 (1H, q, JZ4.9 Hz),
9.84 (1H, s). 13C NMR (125 MHz, DMSO-d6): d 26.3,
124.2, 125.3, 125.4, 125.99, 126.00, 126.3, 126.4, 128.4,
128.5, 130.0 (2C), 131.1, 131.13 (2C), 131.4, 132.1, 132.9,
133.1, 165.0, 165.3. Anal. Calcd (found) for
C21H17Br1N2O2: C, 61.63 (61.26); H, 4.19 (3.90); N,
6.84% (7.00%).
4.2.10. (Z)-2-(2,4-Dimethoxyphenyl)-4-(2-naphthyl-
methylene)-5(4H)-oxazolone. Mp 173.5–174.5 8C. IR
(KBr): 1775, 1655, 1170 cmK1 1H NMR (500 MHz,
.
CDCl3): d 3.92 (3H, s), 4.06 (3H, s), 6.58 (1H, d, JZ
2.1 Hz), 6.64 (1H, dd, JZ2.1, 8.6 Hz), 7.32 (1H, s), 7.51–
7.56 (2H, m), 7.84–7.93 (3H, m), 8.08 (1H, d, JZ8.6 Hz),
8.47 (1H, d, JZ8.9 Hz), 8.56 (1H, s).
4.3. General procedure for the synthesis of (Z)-N-alkyl-
3-(1-naphthyl)-2-(substituted benzoylamino)-2-propen-
amides [(Z)-1a–f,i], (Z)-N-methyl-3-(1-naphthyl)-2-
trimethylacetylamino-2-propenamide [(Z)-1g], (Z)-3-(1-
naphthyl)-2-benzoylamino-2-propenamide [(Z)-1h], and
(Z)-N-methyl-3-(2-naphthyl)-2-(substituted benzoyl-
amino)-2-propenamides [(Z)-1j–l]
4.3.4. (Z)-N-Methyl-3-(1-naphthyl)-2-(4-trifluoromethyl-
benzoylamino)-2-propenamide [(Z)-1d]. Mp 195.0–
196.0 8C. IR (KBr): 1650, 1675, 3170, 3290 cmK1 1H
.
NMR (500 MHz, DMSO-d6): d 2.76 (3H, d, JZ4.9 Hz),
7.44 (1H, dd, JZ6.7, 7.9 Hz), 7.54 (1H, dd, JZ6.1, 7.3 Hz),
7.57 (1H, dd, JZ6.1, 8.9 Hz), 7.61 (1H, d, JZ6.7 Hz), 7.81
(1H, s), 7.83 (2H, d, JZ7.9 Hz), 7.87 (1H, d, JZ7.9 Hz),
(Z)-4-(1-Naphthylmethylene)-2-(substituted phenyl)-

10300
K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
7.94 (1H, d, JZ8.9 Hz), 8.03 (2H, d, JZ7.9 Hz), 8.03 (1H,
d, JZ7.3 Hz), 8.26 (1H, q, JZ4.9 Hz), 10.01 (1H, s). 13C
NMR (125 MHz, DMSO-d6): d 26.3, 123.9 (1C, q, JZ
273.1 Hz), 124.2, 125.1 (2C, q, JZ3.0 Hz), 125.4, 126.0,
126.1, 126.4, 126.7, 128.5, 128.6, 128.7 (2C), 131.1, 131.3,
131.5 (1C, q, JZ31.0 Hz), 131.9, 133.2, 137.6, 164.9,
165.1. Anal. Calcd (found) for C22H17F3N2O2: C, 66.33
(66.12); H, 4.30 (4.06); N, 7.03% (7.16%).
4.3.9. (Z)-2-Benzoylamino-N-benzyl-3-(1-naphthyl)-2-
propenamide [(Z)-1i]. Mp 178.0–178.5 8C. IR (KBr):
1610, 1650, 3060, 3250 cmK1 1H NMR (500 MHz,
.
DMSO-d6): d 4.47 (2H, d, JZ6.1 Hz), 7.25 (1H, dd, JZ
7.3, 7.3 Hz), 7.34 (2H, dd, JZ7.3, 7.3 Hz), 7.40 (2H, d, JZ
7.3 Hz), 7.42–7.46 (3H, m), 7.52 (1H, dd, JZ7.9, 7.9 Hz),
7.55 (1H, dd, JZ7.3, 8.5 Hz), 7.58 (1H, dd, JZ7.3, 7.9 Hz),
7.66 (1H, d, JZ6.7 Hz), 7.84 (1H, s), 7.86 (2H, d, JZ
7.9 Hz), 7.86 (1H, d, JZ7.9 Hz), 7.94 (1H, d, JZ8.5 Hz),
8.05 (1H, d, JZ7.9 Hz), 8.84 (1H, t, JZ6.1 Hz), 9.83 (1H,
s). 13C NMR (125 MHz, DMSO-d6): d 42.6, 124.3, 125.4,
126.0, 126.1, 126.4, 126.6 (2C), 127.2 (2C), 127.9 (2C),
128.1, 128.2, 128.45, 128.53, 131.1, 131.4, 131.5 (2C),
132.4, 133.2 (2C), 133.8, 139.8, 164.9, 166.4. Anal. Calcd
(found) for C27H22N2O2: C, 79.78 (79.51); H, 5.46 (5.87);
N, 6.89% (6.70%).
4.3.5. (Z)-2-(4-Cyanobenzoylamino)-N-methyl-3-(1-
naphthyl)-2-propenamide [(Z)-1e]. Mp 210.0–211.0 8C.
1
IR (KBr): 1650, 1670, 2230, 3290, 3400 cmK1. H NMR
(500 MHz, DMSO-d6): d 2.74 (3H, d, JZ4.9 Hz), 7.42 (1H,
dd, JZ7.3, 8.5 Hz), 7.52–7.55 (2H, m), 7.57 (1H, d, JZ
7.3 Hz), 7.79 (1H, s), 7.85 (1H, d, JZ8.5 Hz), 7.96–7.91
(5H, m), 8.00 (1H, d, JZ7.3 Hz), 8.24 (1H, q, JZ4.9 Hz),
9.99 (1H, s). 13C NMR (125 MHz, DMSO-d6): d 26.3,
113.8, 118.3, 124.2, 125.4, 126.0, 126.1, 126.4, 126.8, 128.5
(2C), 128.6 (2C), 131.1, 131.3, 131.8, 132.2 (2C), 133.2,
137.8, 164.8, 164.9. Anal. Calcd (found) for C22H17N3O2:
C, 74.35 (73.98); H, 4.82 (4.72); N, 11.82% (12.14%).
4.3.10. (Z)-2-Benzoylamino-N-methyl-3-(2-naphthyl)-2-
propenamide [(Z)-1j]. Mp 189.0–190.0 8C. IR (KBr):
1
1628, 3052, 3248 cmK1. H NMR (500 MHz, DMSO-d6):
d 2.72 (3H, d, JZ4.9 Hz) 7.42 (1H, s), 7.49 (1H, dd, JZ6.7,
7.6 Hz), 7.50 (1H, dd, JZ6.7, 7.6 Hz), 7.53 (2H, dd, JZ7.3,
7.9 Hz), 7.60 (1H, dd, JZ7.9, 7.9 Hz), 7.71 (1H, d, JZ
8.5 Hz), 7.78 (1H, d, JZ6.7 Hz), 7.83 (1H, d, JZ8.5 Hz),
7.85 (1H, d, JZ6.7 Hz), 8.03 (2H, d, JZ7.9 Hz), 8.08 (1H,
s), 8.14 (1H, q, JZ4.9 Hz), 9.98 (1H, s). 13C NMR
(125 MHz, DMSO-d6): d 26.3, 126.1, 126.5, 126.7, 127.4,
127.7, 127.9 (2C), 128.0, 128.3 (2C), 128.8, 129.3, 130.5,
131.6, 132.0, 132.6, 132.7, 133.8, 165.4, 165.9. Anal. Calcd
(found) for C21H18N2O2: C, 76.34 (76.30); H, 5.49 (5.60);
N, 8.48% (8.31%).
4.3.6. (Z)-2-(2,4-Dimethoxybenzoylamino)-N-methyl-3-
(1-naphthyl)-2-propenamide [(Z)-1f]. Mp 176.0–
176.5 8C. IR (KBr): 1640, 1665, 3348 cmK1 1H NMR
.
(500 MHz, DMSO-d6): d 2.76 (3H, d, JZ4.3 Hz), 3.59 (3H,
s), 3.79 (3H, s), 6.58 (1H, d, JZ2.5 Hz), 6.62 (1H, dd, JZ
2.5, 8.9 Hz), 7.27 (1H, s), 7.54–7.57 (3H, m), 7.62 (1H, d,
JZ7.3 Hz), 7.77 (1H, d, JZ8.9 Hz), 7.92 (1H, d, JZ
7.9 Hz), 7.98–7.96 (1H, m), 8.08–8.06 (1H, m), 8.22 (1H, q,
JZ4.3 Hz), 9.47 (1H, s). 13C NMR (125 MHz, DMSO-d6):
d 26.2, 55.6, 56.0, 98.5, 106.1, 113.6, 120.1, 124.5, 125.4,
126.10, 126.15, 126.4, 128.2, 128.4, 130.9, 131.4, 132.7,
133.2, 133.4, 158.6, 162.6, 163.4, 165.4. Anal. Calcd
(found) for C23H22N2O4: C, 70.75 (70.41); H, 5.68 (5.61);
N, 7.17% (6.87%).
4.3.11. (Z)-2-(4-Anisoylamino)-N-methyl-3-(2-naphthyl)-
2-propenamide [(Z)-1k]. Mp 138.0–139.5 8C. IR (KBr):
1610, 1640, 3090, 3250 cmK1 1H NMR (500 MHz,
.
DMSO-d6): d 2.72 (3H, d, JZ4.6 Hz), 3.84 (3H, s), 7.07
(2H, d, JZ8.9 Hz), 7.38 (1H, s), 7.48–7.52 (2H, m), 7.70
(1H, d, JZ8.5 Hz), 7.78 (1H, d, JZ8.5 Hz), 7.82 (1H, d,
JZ8.5 Hz), 7.85 (1H, d, JZ7.2 Hz), 8.02 (2H, d, JZ
8.9 Hz), 8.06 (1H, s), 8.13 (1H, q, JZ4.6 Hz), 9.85 (1H, s).
13C NMR (125 MHz, DMSO-d6): d 26.3, 55.4, 113.5 (2C),
126.1, 126.2, 126.5, 126.7, 127.4, 127.7, 128.0, 128.5,
129.3, 129.9 (2C), 130.7, 132.1, 132.6, 132.8, 162.0, 165.5,
165.6. Anal. Calcd (found) for C22H20N2O3: C, 73.32
(72.98); H, 5.59 (5.93); N, 7.77% (7.43%).
4.3.7. (Z)-N-Methyl-3-(1-naphthyl)-2-trimethylacetyl-
amino-2-propenamide [(Z)-1g]. Mp 180.0–181.5 8C. IR
(KBr): 1630, 1650, 3300, 3350 cmK1. 1H NMR (500 MHz,
DMSO-d6): d 1.03 (9H, s), 2.75 (3H, d, JZ4.9 Hz), 7.47
(1H, dd, JZ7.3, 7.9 Hz), 7.53–7.55 (4H, m), 7.84 (1H, q,
JZ4.9 Hz), 7.88 (1H, d, JZ7.9 Hz), 7.93–7.95 (1H, m),
7.98–8.00 (1H, m), 8.75 (1H, s). 13C NMR (125 MHz,
DMSO-d6): d 26.3, 26.9 (3C), 38.3, 124.4, 124.8, 125.2,
125.9, 126.2, 126.3, 128.3, 128.4, 131.0, 131.5, 132.8,
133.1, 165.6, 176.9. Anal. Calcd (found) for C19H22N2O2:
C, 73.52 (73.80); H, 7.14 (7.04); N, 9.03% (9.10%).
4.3.12. (Z)-2-(2,4-Dimethoxybenzoylamino)-N-methyl-3-
(2-naphthyl)-2-propenamide [(Z)-1l]. Mp 173.5–174.5 8C.
1
IR (KBr): 1630, 1643, 3323 cmK1. H NMR (500 MHz,
DMSO-d6): d 2.72 (3H, d, JZ4.6 Hz), 3.85 (3H, s), 3.89
(3H, s), 6.68 (1H, dd, JZ2.3, 8.6 Hz), 6.74 (1H, dd, JZ
2.3 Hz), 7.12 (1H, s), 7.51–7.53 (2H, m), 7.74 (1H, d, JZ
8.6 Hz), 7.82–7.90 (4H, m), 8.06 (1H, q, JZ4.6 Hz), 8.10
(1H, s), 9.63 (1H, s). 13C NMR (125 MHz, DMSO-d6): d
26.2, 55.6, 56.2, 98.5, 106.0, 114.3, 125.3, 126.3, 126.5,
126.6, 127.5, 127.8, 128.0, 128.8, 130.8, 132.1, 132.5,
132.7, 132.8, 158.9, 163.4 (2C), 165.6. Anal. Calcd (found)
for C23H22N2O4: C, 70.75 (70.93); H, 5.68 (6.01); N, 7.17%
(7.08%).
4.3.8. (Z)-2-Benzoylamino-3-(1-naphthyl)-2-propen-
amide [(Z)-1h]. Mp 159.5–160.0 8C. IR (KBr): 1650,
1
1690, 3190, 3280 cmK1. H NMR (500 MHz, DMSO-d6):
d 7.30 (1H, br s), 7.41 (2H, dd, JZ7.3, 7.3 Hz), 7.43 (1H,
dd, JZ7.3, 8.5 Hz), 7.50 (1H, dd, JZ7.3, 7.3 Hz), 7.54 (1H,
dd, JZ6.7, 8.6 Hz), 7.57 (1H, dd, JZ6.7, 7.9 Hz), 7.62 (1H,
d, JZ7.3 Hz), 7.75 (1H, s), 7.75 (1H, br s), 7.82 (2H, d, JZ
7.3 Hz), 7.85 (1H, d, JZ8.5 Hz), 7.92 (1H, d, JZ8.6 Hz),
8.04 (1H, d, JZ7.9 Hz), 9.71 (1H, s). 13C NMR (125 MHz,
DMSO-d6): d 124.3, 125.4, 126.1, 126.2 (2C), 126.4, 127.8
(2C), 128.2 (2C), 128.47, 128.5, 131.2, 131.5, 131.6, 132.5,
133.2, 133.9, 166.2, 166.7. Anal. Calcd (found) for
C20H16N2O2: C, 75.93 (75.61); H, 5.10 (5.13); N, 8.86%
(8.96%).
4.4. General procedure for the irradiation of (Z)-1a–l
In order to examine the dependence of product distribution

K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
10301
and composition on irradiation time, a MeOH solution
(45 mL) of (Z)-1 (3.75!10K3 mol dmK3) containing TEA
(0.10 mol dmK3, for 1a–i), or DBU (0.10 mol dmK3, for
1j–l) placed in a Pyrex vessel, was irradiated under nitrogen
at room temperature with Pyrex-filtered light from a 450 W
high-pressure Hg lamp (external irradiation). At suitable
time intervals, an aliquot (5 mL) of the solution was pipetted
off and concentrated to dryness in vacuo. The resulting
4.8 Hz), 7.84 (1H, d, JZ8.6 Hz), 7.92–7.95 (2H, m), 7.93
(1H, s), 8.08 (1H, d, JZ7.9 Hz), 9.96 (1H, s). 13C NMR
(125 MHz, DMSO-d6): d 25.9, 55.6, 56.4, 98.7, 106.3,
114.0, 114.1, 124.6, 125.4, 125.7, 125.9, 126.1, 127.4,
128.3, 131.3, 132.4, 132.7, 133.2, 133.8, 158.7, 162.8,
163.5, 165.3. Anal. Calcd (found) for C23H22N2O4: C, 70.75
(70.62); H, 5.68 (5.77); N, 7.17% (7.32%).
1
residue was dissolved in DMSO-d6 and subjected to H
4.4.3. (E)-1h. Yield, 12% (conversion, 6%). Mp 160.5–
161.5 8C. IR (KBr): 1666, 1690, 3368, 3464 cmK1 1H
.
NMR spectral analysis. When DBU was used as an electron
donor, the resulting residue was at first dissolved in CHCl3
and subsequently washed with 0.2 mol dmK3 HCl solution
(20 mL). After removal of CHCl3 under reduced pressure,
the resulting residue was dissolved in DMSO-d6 and
subjected to 1H NMR spectral analysis. The product
composition was estimated from the area ratio of a given
1H NMR signal for each compound.
NMR (500 MHz, DMSO-d6): d 7.14 (1H, br s), 7.30 (1H, s),
7.34 (1H, br s), 7.46 (1H, dd, JZ7.3, 8.2 Hz), 7.54 (2H, dd,
JZ7.3, 8.5 Hz), 7.54–7.58 (3H, m), 7.61 (1H, dd, JZ7.3,
7.3 Hz), 7.84 (1H, d, JZ8.2 Hz), 7.93–7.95 (1H, m), 7.99
(2H, d, JZ8.5 Hz), 8.05–8.07 (1H, m), 10.24 (1H, s). 13C
NMR (125 MHz, DMSO-d6): d 116.2, 124.6, 125.4, 125.9,
126.0, 126.1, 127.4, 127.7 (2C), 128.26 (2C), 128.32 (2C),
131.3, 131.7, 132.3, 133.1, 133.9, 165.0, 166.0. Anal. Calcd
(found) for C20H16N2O2: C, 75.93 (75.72); H, 5.10 (5.35);
N, 8.86% (8.75%).
On the other hand, a MeOH solution (200 mL) of (Z)-1a–l
(3.75!10K3 mol dmK3) containing TEA (0.10 mol dmK3
,
for 1a–i) or DBU (0.10 mol dmK3, for 1j–l), placed in a
Pyrex vessel, was irradiated for a given period of time under
nitrogen with Pyrex-filtered light from a 400 W high-
pressure Hg lamp at room temperature (internal irradiation).
After 3-h (1b), 6-h (1a,c,f–l), 10-h (1d), or 30-h (1e)
irradiation, an appropriate amount of the solution (5 mL)
being irradiated was pipetted off and concentrated to
dryness in vacuo giving the residue which was subjected
to 1H NMR spectral analysis in DMSO-d6. DBU was
removed according to the same procedure as above. The
remaining solutions of 1a–l were concentrated to dryness
under reduced pressure. The resulting residues were washed
with a small amount of EtOH, allowing us to obtain
analytical-grade 2a–l. The combined filtrates were concen-
trated to dryness and subjected to column chromatography
over silica gel (230 mesh, Merck) eluting with EtOAc–
hexane. For the purpose of isolating and purifying the
photoproducts, preparative TLC plate (silica gel) was also
used. Physical and spectroscopic properties of the isolated
isomers [(E)-1a,f,h–j], 3,4-dihydrobenzo[f]quinolinones
(2a–i), 3,4-dihydrobenzo[h]quinolinones (2j–l) and 4,5-
dihydrooxazoles (cis-3a,h,i) are as follows. Conversion was
estimated by the sum of composition for 2 and 3.
4.4.4. (E)-1i. Yield, 10% (conversion, 6%). Mp 155.5–
157.0 8C. IR (KBr): 1627, 1644, 3256, 3330 cmK1 1H
.
NMR (500 MHz, DMSO-d6): d 4.19 (2H, d, JZ6.1 Hz),
6.97–6.99 (2H, m), 7.14–7.16 (3H, m), 7.32 (1H, s), 7.33
(1H, dd, JZ7.3, 8.5 Hz), 7.42 (1H, d, JZ6.7 Hz), 7.53–7.57
(2H, m), 7.55 (2H, dd, JZ7.3, 7.9 Hz), 7.62 (1H, dd, JZ7.9,
7.9 Hz), 7.84 (1H, d, JZ8.5 Hz), 7.94 (1H, d, JZ7.9 Hz),
8.01 (2H, d, JZ7.3 Hz), 8.07 (2H, d, JZ7.3 Hz), 8.44 (1H,
t, JZ6.1 Hz), 10.34 (1H, s). 13C NMR (125 MHz, DMSO-
d6): d 42.3, 124.7, 125.4, 125.9, 126.0 (2C), 126.4, 127.3
(2C), 127.4 (2C), 127.8 (2C), 127.9 (2C), 128.3, 128.4 (2C),
131.4, 131.8, 132.1, 133.1, 133.9, 134.9, 138.9, 164.6,
165.0. Anal. Calcd (found) for C27H22N2O2: C, 79.78
(79.37); H, 5.46 (5.87); N, 6.89% (6.80%).
4.4.5. (E)-1j. Yield, 10% (conversion, 4%). Mp 167.0–
168.0 8C. IR (KBr): 1643, 3059, 3260 cmK1 1H NMR
.
(500 MHz, DMSO-d6): d 2.60 (3H, d, JZ4.9 Hz), 6.89 (1H,
s), 7.43 (1H, d, JZ8.5 Hz), 7.47 (1H, dd, JZ7.3, 7.3 Hz),
7.49 (1H, dd, JZ7.3, 7.3 Hz), 7.53 (2H, dd, JZ7.3, 8.3 Hz),
7.60 (1H, dd, JZ7.3, 7.3 Hz), 7.79 (1H, s), 7.83 (1H, d, JZ
7.3 Hz), 7.85 (1H, d, JZ8.5 Hz), 7.95 (2H, d, JZ8.3 Hz),
8.08 (1H, q, JZ4.9 Hz), 10.20 (1H, s). 13C NMR (125 MHz,
DMSO-d6): d 25.8, 118.0, 125.9, 126.1, 126.2, 126.9, 127.3
(2C), 127.7 (3C), 128.3 (2C), 131.7, 131.9, 132.7, 132.9,
133.8, 133.9, 164.8, 165.1. Anal. Calcd (found) for
C21H18N2O2: C, 76.34 (76.18); H, 5.49 (5.32); N, 8.48%
(8.40%).
4.4.1. (E)-1a. Yield, 10% (conversion, 7%). Mp 171.0–
172.0 8C. IR (KBr): 1678, 1664, 3264, 3320 cmK1 1H
.
NMR (500 MHz, DMSO-d6): d 2.46 (3H, d, JZ4.9 Hz),
7.33 (1H, s), 7.43–7.47 (2H, m), 7.54 (2H, dd, JZ7.3,
7.9 Hz), 7.54–7.58 (2H, m), 7.61 (1H, dd, JZ7.3, 7.3 Hz),
7.83 (1H, d, JZ7.3 Hz), 7.83 (1H, q, JZ4.9 Hz), 7.94 (1H,
d, JZ6.4 Hz), 7.98 (2H, d, JZ7.9 Hz), 8.07 (1H, d, JZ
7.9 Hz), 10.27 (1H, s). 13C NMR (125 MHz, DMSO-d6): d
25.7, 115.7, 124.4, 125.3, 125.4, 125.8, 126.0, 127.3, 127.7
(2C), 128.2, 128.3 (2C), 131.2, 131.7, 132.0, 133.0, 133.7,
134.8, 164.8, 164.9. Anal. Calcd (found) for C21H18N2O2:
C, 76.34 (76.34); H, 5.49 (5.81); N, 8.48% (8.47%).
4.4.6. 3-Benzoylamino-3,4-dihydro-1-methyl-2(1H)-benzo-
[f]quinolinone (2a). Yield, 67% (conversion, O99%). Mp
167.0–168.0 8C. IR (KBr): 1630, 1690, 3090, 3340 cmK1
.
1H NMR (500 MHz, DMSO-d6): d 3.28 (1H, dd, JZ15.3,
15.3 Hz), 3.45 (3H, s), 3.74 (1H, dd, JZ6.7, 15.3 Hz), 4.86
(1H, ddd, JZ6.7, 8.5, 15.3 Hz), 7.46 (1H, dd, JZ6.7,
7.3 Hz), 7.52 (1H, d, JZ8.5 Hz), 7.53 (2H, dd, JZ6.7,
7.3 Hz), 7.57 (1H, dd, JZ6.7, 8.5 Hz), 7.59 (1H, dd, JZ7.3,
7.3 Hz), 7.93 (1H, d, JZ7.3 Hz), 7.96 (2H, d, JZ6.7 Hz),
7.96 (1H, d, JZ8.5 Hz), 8.06 (1H, d, JZ8.5 Hz), 8.86 (1H,
d, JZ8.5 Hz). 13C NMR (125 MHz, DMSO-d6): d 26.7,
30.4, 48.5, 116.1, 117.6, 123.0, 124.5, 127.1, 127.3 (2C),
128.1, 128.4 (3C), 129.6, 130.5, 131.5, 134.1, 137.2, 166.2,
4.4.2. (E)-1f. Yield, 6% (conversion, 12%). Mp 191.0–
192.0 8C. IR (KBr): 1608, 1636, 2945, 3347 cmK1 1H
.
NMR (500 MHz, DMSO-d6): d 2.45 (3H, d, JZ4.8 Hz),
3.87 (3H, s), 4.00 (3H, s), 6.72 (1H, dd, JZ2.1, 8.6 Hz),
6.74 (1H, d, JZ2.1 Hz), 7.38 (1H, d, JZ7.6 Hz), 7.46 (1H,
dd, JZ7.6, 7.9 Hz), 7.54–7.60 (2H, m), 7.65 (1H, q, JZ

10302
K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
168.3. Anal. Calcd (found) for C21H18N2O2: C, 76.34
(76.10); H, 5.49 (5.50); N, 8.48% (8.70%).
129.6, 130.4, 132.4 (2C), 137.0, 138.0, 164.8, 167.9. Anal.
Calcd (found) for C22H17N3O2: C, 74.35 (74.36); H, 4.82
(4.86); N, 11.82% (11.71%).
4.4.7. 3-(4-Anisoylamino)-3,4-dihydro-1-methyl-2(1H)-
benzo[f]quinolinone (2b). Yield, 80% (conversion,
O99%). Mp 172.0–173.0 8C. IR (KBr): 1640, 1690, 3300,
4.4.11. 3,4-Dihydro-3-(2,4-dimethoxybenzoylamino)-1-
methyl-2(1H)-benzo[f]quinolinone (2f). Yield, 87% (con-
version, O99%). Mp 198.0–199.0 8C. IR (KBr): 1610,
1
3400 cmK1. H NMR (500 MHz, DMSO-d6): d 3.25 (1H,
1
dd, JZ14.7, 15.3 Hz), 3.33 (3H, s), 3.44 (3H, s), 3.72 (1H,
dd, JZ6.1, 15.3 Hz), 4.84 (1H, ddd, JZ6.1, 7.9, 14.7 Hz),
7.06 (2H, d, JZ9.2 Hz), 7.45 (1H, dd, JZ7.3, 7.9 Hz), 7.51
(1H, d, JZ9.2 Hz), 7.56 (1H, dd, JZ7.9, 8.5 Hz), 7.96–7.92
(4H, m), 8.06 (1H, d, JZ8.5 Hz), 8.70 (1H, d, JZ7.9 Hz).
13C NMR (125 MHz, DMSO-d6): d 26.7, 30.3, 48.3, 55.3,
113.5 (2C), 116.0, 117.6, 123.0, 124.4, 126.2, 126.9, 127.9,
128.3, 129.1 (2C), 129.5, 130.5, 137.1, 161.6, 165.5, 168.4.
Anal. Calcd (found) for C22H20N2O3: C, 73.32 (73.69); H,
5.59 (5.63); N, 7.77% (7.78%).
1643, 3352 cmK1. H NMR (500 MHz, DMSO-d6): d 3.05
(1H, dd, JZ15.3, 14.7 Hz), 3.47 (3H, s), 3.86 (3H, s), 3.99
(3H, s), 4.04 (1H, dd, JZ15.3, 6.1 Hz), 4.63 (1H, ddd, JZ
14.7, 6.1, 5.5 Hz), 6.69 (1H, dd, JZ8.8, 2.4 Hz), 6.73 (1H,
d, JZ2.4 Hz), 7.47 (1H, d, JZ7.3, 6.7 Hz), 7.53 (1H, d, JZ
9.2 Hz), 7.58 (1H, dd, JZ8.5, 6.7 Hz), 7.94 (1H, d, JZ
9.2 Hz), 7.95 (1H, d, JZ7.3 Hz), 7.98 (1H, d, JZ8.8 Hz),
8.03 (1H, d, JZ8.5 Hz), 8.90 (1H, d, JZ5.5 Hz). 13C NMR
(125 MHz, DMSO-d6): d 168.4, 164.0, 163.3, 159.0, 137.0,
132.8, 130.6, 129.7, 128.4, 128.0, 127.1, 124.6, 123.1,
118.0, 116.2, 113.7, 106.0, 98.7, 56.3, 55.5, 49.2, 30.5, 26.6.
Anal. Calcd (found) for C22H22N2O4: C, 70.75 (70.43); H,
5.68 (5.41); N, 7.17% (7.13%).
4.4.8. 3-(4-Bromobenzoylamino)-3,4-dihydro-1-methyl-
2(1H)-benzo[f]quinolinone (2c). Yield, 77% (conversion,
O99%). Mp 209.0–210.0 8C. IR (KBr): 1640, 1685, 3300,
1
3350 cmK1. H NMR (500 MHz, DMSO-d6): d 3.26 (1H,
4.4.12. 3,4-Dihydro-1-methyl-3-trimethylacetylamino-
2(1H)-benzo[f]quinolinone (2g). Yield, 75% (conversion,
O99%). Mp 220.0–221.5 8C. IR (KBr): 1650, 1690,
dd, JZ14.7, 15.3 Hz) 3.44 (3H, s), 3.73 (1H, dd, JZ6.1,
15.3 Hz), 4.84 (1H, ddd, JZ6.1, 8.5, 14.7 Hz), 7.46 (1H, dd,
JZ6.7, 7.9 Hz), 7.51 (1H, d, JZ9.2 Hz), 7.56 (1H, dd, JZ
7.3, 7.9 Hz), 7.75 (2H, d, JZ8.5 Hz), 7.91 (2H, d, JZ
8.5 Hz), 7.93 (1H, d, JZ9.2 Hz), 7.95 (1H, d, JZ6.7 Hz),
8.06 (1H, d, JZ7.3 Hz), 8.98 (1H, d, JZ8.5 Hz). 13C NMR
(125 MHz, DMSO-d6): d 20.6, 30.4, 48.6, 116.1, 117.5,
123.1, 124.6, 125.3, 127.1, 128.1, 128.4, 129.6 (2C), 129.7,
130.6, 131.5 (2C), 133.2, 137.2, 165.4, 168.2. Anal. Calcd
(found) for C21H17BrN2O2: C, 61.63 (61.47); H, 4.19 (4.20);
N, 6.84% (7.08%).
1
3360 cmK1. H NMR (500 MHz, DMSO-d6): d 1.20 (9H,
s), 3.15 (1H, dd, JZ14.6, 15.3 Hz), 3.41 (3H, s), 3.60 (1H,
dd, JZ6.7, 15.3 Hz), 4.59 (1H, ddd, JZ6.7, 7.3, 14.6 Hz),
7.44 (1H, dd, JZ7.3, 7.3 Hz), 7.48 (1H, d, JZ8.6 Hz), 7.56
(1H, dd, JZ7.3, 8.5 Hz), 7.76 (1H, d, JZ7.3 Hz), 7.92 (1H,
d, JZ7.3 Hz), 7.93 (1H, d, JZ8.6 Hz), 8.02 (1H, d, JZ
8.5 Hz). 13C NMR (125 MHz, DMSO-d6): d 26.5, 27.4 (3C),
30.3, 38.2, 47.9, 116.1, 117.7, 123.0, 124.5, 127.0, 127.9,
128.3, 129.6, 130.5, 137.1, 168.5, 177.5. Anal. Calcd
(found) for C19H22N2O2: C, 73.52 (73.92); H, 7.14 (7.21);
N, 9.03% (9.18%).
4.4.9. 3,4-Dihydro-1-methyl-3-(4-trifluoromethylbenzoyl-
amino)-2(1H)-benzo[f]quinolinone (2d). Yield, 75% (con-
version, O99%). Mp 213.0–214.0 8C. IR (KBr): 1640,
4.4.13. 3-Benzoylamino-3,4-dihydro-2(1H)-benzo[f]quino-
linone (2h). Yield, 59% (conversion, 94%). Mp 184.0–
1
1690, 3310 cmK1. H NMR (500 MHz, DMSO-d6): d 3.28
(1H, dd, JZ14.6, 15.3 Hz), 3.45 (3H, s), 3.77 (1H, dd, JZ
6.1, 15.3 Hz), 4.88 (1H, ddd, JZ6.1, 8.5, 14.6 Hz), 7.46
(1H, dd, JZ7.3, 7.9 Hz), 7.52 (1H, d, JZ8.6 Hz), 7.56 (1H,
dd, JZ7.3, 8.5 Hz), 7.93 (2H, d, JZ8.2 Hz), 7.94 (1H, d,
JZ7.9 Hz), 7.96 (1H, d, JZ8.6 Hz), 8.07 (1H, d, JZ
8.5 Hz), 8.16 (2H, d, JZ8.2 Hz), 9.15 (1H, d, JZ8.5 Hz).
13C NMR (125 MHz, DMSO-d6): d 26.5, 30.4, 48.6, 116.1,
117.5, 123.1, 123.9 (1C, q, JZ272.1 Hz), 124.5, 125.4 (2C,
q, JZ4.1 Hz), 127.0, 128.1, 128.3 (2C), 128.34, 129.6,
130.5, 131.3 (1C, q, JZ31.0 Hz), 137.1, 137.9, 165.1,
168.1. Anal. Calcd (found) for C22H17F3N2O2: C, 66.20
(66.20); H, 4.30 (3.97); N, 7.03% (6.87%).
186.0 8C. IR (KBr): 1650, 1680, 1746, 2944, 3404 cmK1
.
1H NMR (500 MHz, DMSO-d6): d 1.54 (3H, d, JZ6.7 Hz),
3.29 (1H, dd, JZ15.2, 14.6 Hz), 3.62 (3H, s), 3.70 (1H, dd,
JZ15.2, 6.1 Hz), 4.80 (1H, ddd, JZ14.6, 8.6, 6.1 Hz), 5.35
(1H, q, JZ6.7 Hz), 7.48 (1H, dd, JZ7.9, 7.9 Hz), 7.52 (2H,
dd, JZ7.3, 7.9 Hz), 7.58 (1H, d, JZ9.2 Hz), 7.58–7.60 (2H,
m), 7.94 (1H, d, JZ9.2 Hz), 7.94 (1H, d, JZ7.9 Hz), 7.95
(2H, d, JZ7.3 Hz), 8.09 (1H, d, JZ8.5 Hz), 8.90 (1H, d,
JZ8.6 Hz). 13C NMR (125 MHz, DMSO-d6): d 15.1, 26.8,
48.6, 52.1, 53.5, 116.1, 119.1, 123.3, 124.8, 127.2, 127.4
(2C), 128.2, 128.3 (3C), 129.9, 130.6, 131.5, 134.0, 136.3,
166.1, 168.3, 171.0. Anal. Calcd (found) for C24H22N2O4:
C, 71.63 (71.80); H, 5.51 (5.34); N, 6.96% (6.59%).
4.4.10. 3-(4-Cyanobenzoylamino)-3,4-dihydro-1-methyl-
2(1H)-benzo[f]quinolinone (2e). Yield, 60% (conversion,
O99%). Mp 217.0–218.0 8C. IR (KBr): 1632, 1674, 2230,
4.4.14. 3-Benzoylamino-1-benzyl-3,4-dihydro-2(1H)-
benzo[f]quinolinone (2i). Yield, 55% (conversion, 96%).
1
3316 cmK1. H NMR (500 MHz, DMSO-d6): d 3.27 (1H,
Mp194.0–195.0 8C. IR(KBr): 1640, 1690, 3090, 3340 cmK1
.
dd, JZ15.2, 15.2 Hz), 3.44 (3H, s), 3.76 (1H, dd, JZ6.7,
15.2 Hz), 4.86 (1H, ddd, JZ6.7, 8.5, 15.2 Hz), 7.46 (1H, dd,
JZ6.7, 7.3 Hz), 7.52 (1H, d, JZ8.6 Hz), 7.57 (1H, dd, JZ
6.7, 8.5 Hz), 7.93 (1H, d, JZ7.3 Hz), 7.95 (1H, d, JZ
8.6 Hz), 8.03 (2H, d, JZ8.6 Hz), 8.06 (1H, d, JZ8.5 Hz),
8.11 (2H, d, JZ8.6 Hz), 9.17 (1H, d, JZ8.5 Hz). 13C NMR
(125 MHz, DMSO-d6): d 26.4, 30.3, 48.6, 113.7, 116.0,
117.4, 118.2, 123.0, 124.5, 127.0, 128.0, 128.1 (2C), 128.3,
1H NMR (500 MHz, DMSO-d6): d 3.37 (1H, dd, JZ14.3,
14.3 Hz), 3.82 (1H, dd, JZ6.4, 14.3 Hz), 5.06 (1H, ddd, JZ
6.4, 8.2, 14.3 Hz), 5.33 (1H, d, JZ16.5 Hz), 5.37 (1H, d,
JZ16.5 Hz), 7.24–7.20 (1H, m), 7.34–7.28 (4H, m), 7.38
(1H, d, JZ9.2 Hz), 7.44 (1H, dd, JZ7.0, 7.0 Hz), 7.54 (2H,
dd, JZ7.0, 7.6 Hz), 7.56 (1H, dd, JZ7.0, 7.6 Hz), 7.60 (1H,
dd, JZ7.6, 7.6 Hz), 7.80 (1H, d, JZ9.2 Hz), 7.85 (1H, d,
JZ7.0 Hz), 8.00 (2H, d, JZ7.0 Hz), 8.07 (1H, d, JZ

K. Maekawa et al. / Tetrahedron 60 (2004) 10293–10304
10303
7.6 Hz), 8.96 (1H, d, JZ8.2 Hz). 13C NMR (125 MHz,
DMSO-d6): d 26.8, 45.4, 48.5, 116.4, 118.2, 123.2, 124.7,
126.5 (2C), 127.0, 127.1, 127.4 (2C), 128.0, 128.3, 128.4
(2C), 128.6 (2C), 129.7, 130.7, 131.5, 134.1, 136.1, 137.2,
166.3, 168.8. Anal. Calcd (found) for C27H22N2O2: C, 79.78
(79.95); H, 5.46 (5.55); N, 6.89% (6.99%).
7.3 Hz), 8.07 (2H, d, JZ7.3 Hz), 8.07 (1H, d, JZ7.3 Hz).
13C NMR (500 MHz, DMSO-d6): d 25.0, 73.6, 80.2, 123.3,
123.8, 124.8, 125.5, 125.8, 127.1, 128.0, 128.2, 128.3 (2C),
128.6 (2C), 130.2, 132.0, 132.7, 132.9, 164.8, 167.9. EI-MS
(m/z, %): 330 (MC, 56.91).
4.4.19. cis-4-Aminocarbonyl-5-(1-naphthyl)-2-phenyl-
4,5-dihydrooxazole (3h). Yield, 3% (conversion, 94%).
4.4.15. 3-Benzoylamino-3,4-dihydro-1-methyl-2(1H)-
benzo[h]quinolinone (2j). Yield, 35% (conversion, 72%).
Mp 153.0–154.0 8C. IR (KBr): 1636, 1690, 3237 cmK1. 1H
NMR (500 MHz, DMSO-d6): d 3.06–3.10 (1H, m), 3.30–
3.36 (1H, m), 3.50 (3H, s), 4.73–4.78 (1H, m), 7.48 (1H, d,
JZ8.5 Hz), 7.53 (2H, dd, JZ7.3, 7.3 Hz), 7.54 (1H, dd, JZ
7.3, 8.5 Hz), 7.56 (1H, dd, JZ7.3, 8.6 Hz), 7.58 (1H, dd,
JZ7.3, 7.3 Hz), 7.75 (1H, d, JZ8.6 Hz), 7.95 (1H, d, JZ
7.3 Hz), 7.97 (1H, d, JZ8.5 Hz), 8.03 (1H, d, JZ8.6 Hz),
8.74 (1H, d, JZ7.9 Hz). 13C NMR (125 MHz, DMSO-d6): d
31.6, 37.9, 49.2, 123.4, 124.8, 124.9, 125.3, 125.5, 125.7,
125.9, 127.3 (2C), 128.3 (2C), 128.6, 131.4, 133.8, 134.0,
136.5, 166.2, 171.1. Anal. Calcd (found) for C21H18N2O2:
C, 76.34 (76.28); H, 5.49 (5.24); N, 8.48% (8.35%).
1
IR (KBr): 3453, 3321, 1667 cmK1. H NMR (500 MHz,
DMSO-d6): d 5.32 (1H, d, JZ10.4 Hz), 6.67 (1H, s), 6.76
(1H, d, JZ10.4 Hz), 7.02 (1H, s), 7.45 (1H, dd, JZ7.3,
7.9 Hz), 7.53–7.51 (3H, m), 7.56 (2H, dd, JZ6.7, 7.9 Hz),
7.63 (1H, dd, JZ7.9, 7.9 Hz), 7.84 (1H, d, JZ7.9 Hz), 7.91
(1H, d, JZ7.3 Hz), 8.05 (2H, d, JZ6.7 Hz), 8.05 (1H, d,
JZ7.9 Hz). 13C NMR (500 MHz, DMSO-d6): d 73.2, 80.3,
123.6, 124.1, 125.1, 125.6, 126.0, 127.2, 128.1, 128.3 (3C),
128.7 (2C), 130.3, 132.0, 132.9, 133.0, 164.6, 169.6. EI-MS
(m/z, %): 316 (MC, 48.36).
4.4.20. cis-4-Benzylaminocarbonyl-5-(1-naphthyl)-2-
phenyl-4,5-dihydrooxazole (3i). Yield, 10% (conversion,
96%). IR (KBr): 3265, 1657, 1645 cmK1 1H NMR
.
4.4.16. 3-(4-Anisoylamino)-3,4-dihydro-1-methyl-2(1H)-
benzo[h]quinolinone (2k). Yield, 40% (conversion, 85%).
Mp 224.0–225.0 8C. IR (KBr): 1660, 1680, 3400 cmK1. 1H
NMR (500 MHz, DMSO-d6): d 3.07 (1H, dd, JZ5.5,
15.6 Hz), 3.29–3.38 (1H, m), 3.50 (3H, s), 3.84 (3H, s), 4.75
(1H, ddd, JZ5.5, 7.9, 14.2 Hz), 7.05 (2H, d, JZ9.2 Hz),
7.47 (1H, d, JZ8.5 Hz), 7.53 (1H, dd, JZ7.9, 9.2 Hz), 7.57
(1H, dd, JZ7.9, 8.5 Hz), 7.75 (1H, d, JZ8.5 Hz), 7.94 (2H,
d, JZ9.2 Hz), 7.97 (1H, d, JZ9.2 Hz), 8.02 (1H, d, JZ
8.5 Hz), 8.60 (1H, d, JZ7.9 Hz). 13C NMR (125 MHz,
DMSO-d6): d 31.7, 37.8, 49.0, 55.3, 113.5 (2C), 123.3,
124.7, 124.8, 125.3, 125.4, 125.6, 125.8, 126.1, 128.6, 129.2
(2C), 133.7, 136.5, 161.7, 165.6, 171.3. Anal. Calcd (found)
for C22H20N2O3: C, 73.32 (73.14); H, 5.59 (5.63); N, 7.77%
(7.74%).
(500 MHz, DMSO-d6): d 3.77 (1H, dd, JZ5.8, 15.3 Hz),
3.81 (1H, dd, JZ6.1, 15.3 Hz), 5.47 (1H, d, JZ10.7 Hz),
6.43 (2H, d, JZ7.3 Hz), 6.83 (1H, d, JZ10.7 Hz), 7.02 (2H,
dd, JZ7.0, 7.3 Hz), 7.07 (1H, dd, JZ7.0, 7.0 Hz), 7.45 (1H,
dd, JZ7.6, 7.6 Hz), 7.59–7.53 (5H, m), 7.65 (1H, dd, JZ
7.3, 7.3 Hz), 7.90 (1H, d, JZ7.6 Hz), 7.99–7.97 (1H, m),
8.08 (2H, d, JZ8.6 Hz), 8.11–8.07 (1H, m), 8.13 (1H, dd,
JZ5.8, 6.1 Hz). 13C NMR (500 MHz, DMSO-d6): d 41.6,
73.3, 80.4, 123.6, 123.9, 125.1, 125.6, 126.0, 126.2, 126.5
(2C), 127.1, 127.8 (2C), 128.1, 128.25 (2C), 128.3, 128.7
(2C), 130.2, 132.0, 132.6, 132.9, 137.6, 138.6, 164.7, 167.6.
EI-MS (m/z, %): 406 (MC, 32.06).
Acknowledgements
4.4.17. 3,4-Dihydro-3-(2,4-dimethoxybenzoylamino)-1-
methyl-2(1H)-benzo[h]quinolinone (2l). Yield, 30% (con-
version, 70%). Mp 198.0–198.5 8C. IR (KBr): 3360, 1672,
This research was partially supported by a ‘High-Tech
Research Project’ from the Ministry of Education, Sports,
Culture, Science and Technology, Japan.
1
1639 cmK1. H NMR (500 MHz, DMSO-d6): d 3.07 (1H,
dd, JZ14.4, 15.1 Hz), 3.41 (1H, dd, JZ5.5, 15.1 Hz), 3.52
(3H, s), 3.85 (3H, s), 4.00 (3H, s), 4.58 (1H, ddd, JZ5.5,
5.5, 14.4 Hz), 6.69 (1H, dd, JZ2.1, 8.3 Hz), 6.73 (1H, d,
JZ2.1 Hz), 7.49 (1H, d, JZ8.3 Hz), 7.54 (1H, dd, JZ6.9,
7.6 Hz), 7.57 (1H, dd, JZ6.9, 8.3 Hz), 7.77 (1H, d, JZ
8.3 Hz), 7.95 (1H, d, JZ8.3 Hz), 7.98 (1H, d, JZ7.6 Hz),
8.01 (1H, d, JZ8.3 Hz), 8.95 (1H, d, JZ5.5 Hz). 13C NMR
(125 MHz, DMSO-d6): d 33.6, 39.5, 51.5, 57.2, 57.9, 100.3,
107.7, 115.2, 125.0, 126.5, 126.8, 126.9, 127.2, 127.4,
127.6, 130.3, 134.4, 135.4, 138.1, 160.7, 164.9, 165.3,
172.8. Anal. Calcd (found) for C22H22N2O4: C, 70.75
(70.76); H, 5.68 (5.95); N, 7.17% (7.22%).
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