Electron transfer-initiated photocyclization of substituted N-acetyl-α-dehydro(1-naphthyl)alanines to 1,2-dihydrobenzo[f]quinolinone derivatives: Scope and limitations

Article abstract of DOI:10.1016/S0040-4020(01)00477-X

The irradiation of substituted N-acetyl-α-dehydro(1-naphthyl)alanines (1) in MeOH containing triethylamine with Pyrex-filtered light gave 1,2-dihydrobenzo[f]quinolinones (2) in preference to benzo[f]isoquinolines (3) and 1-azetines (4). Analysis of substituent effects on the product compositions revealed that the selectivity of 2 has a strong tendency to decrease with increasing steric bulkiness of the alkyl substituent introduced into the starting (Z)-1. From control and fluorescence quenching experiments it was shown that the photocyclization reaction of 1 affording 2 proceeds by an electron-transfer mechanism. The mechanism of this novel cyclization was discussed mainly based on substituent and solvent effects on both the reactivities of the excited singlet-state 1 and the selectivities of the products 2-4.

Full text of DOI:10.1016/S0040-4020(01)00477-X

TETRAHEDRON
Pergamon
Tetrahedron 57 &2001) 5515±5526
Electron transfer-initiated photocyclization of substituted
N-acetyl-a-dehydroꢀ1-naphthyl)alanines to
1,2-dihydrobenzo[f]quinolinone derivatives:
scope and limitations
Kei Maekawa,a Tetsutaro Igarashi,a Kanji Kubob and Tadamitsu Sakuraia,p
aDepartment of Applied Chemistry, Faculty of Engineering, Kanagawa University, Kanagawa-ku, Yokohama 221-8686, Japan
bInstitute of Advanced Material Study, 86 Kyushu University, Kasuga-Koen, Kasuga, Fukuoka 816-0811, Japan
Received 13 March 2001; accepted 1 May 2001
AbstractÐThe irradiation of substituted N-acetyl-a-dehydro&1-naphthyl)alanines &1) in MeOH containing triethylamine with Pyrex-®ltered
light gave 1,2-dihydrobenzo[f]quinolinones &2) in preference to benzo[f]isoquinolines &3) and 1-azetines &4). Analysis of substituent effects
on the product compositions revealed that the selectivity of 2 has a strong tendency to decrease with increasing steric bulkiness of the alkyl
substituent introduced into the starting &Z)-1. From control and ¯uorescence quenching experiments it was shown that the photocyclization
reaction of 1 affording 2 proceeds by an electron-transfer mechanism. The mechanism of this novel cyclization was discussed mainly based
on substituent and solvent effects on both the reactivities of the excited singlet-state 1 and the selectivities of the products 2±4. q 2001
Elsevier Science Ltd. All rights reserved.
1. Introduction
induced ET reactions proceed in high chemical and
quantum yields enabling the construction of heteroatom-
containing polycyclic compounds.5,6 In the course of our
systematic study towards the characterization of the
excited-state reactions of substituted a-dehydrophenyl-
alanines, we have discovered interesting photocyclization
reactions giving isoquinoline and/or 1-azetine derivatives.7
If we introduce a naphthyl group &instead of a phenyl) into
a-dehydroamino acids, it is expected that we might be
able to explore ET-initiated photoreactions of naphthyl-
substituted a-dehydroamino acid derivatives in the presence
of an aliphatic amine.8 Taking into account the fact that
aromatic ole®ns such as styrene and stilbene derivatives
show diverse excited-state reactivities of synthetic utility,5,9
our attention is focused on the photo-induced ET reactions
of N-acetyl-a-dehydro&1-naphthyl)alanine derivatives &1) in
the presence of triethylamine &TEA) which may serve as an
electron donor. In this paper, we highlight the scope and
limitations of ET photochemistry of 1 in the synthesis of
heterocyclic compounds having the benzoquinolinone
skeleton, as well as the mechanism of the novel photo-
cyclization reactions initiated by ET.
Synthetic organic photochemistry has continued to
contribute to the development of ef®cient and selective
transformations for the preparation of natural products as
well as complicated molecules which could not have been
synthesized by conventional methods.1 It is well-known that
many of naturally occurring a,b-unsaturated-a-amino acids
&a-dehydroamino acids) and a-dehydropeptides possess a
variety of biological activities,2 allowing us to expect the
potential pharmacological and physiological usefulness
of these dehydroamino acid-derived products. Ef®cient
synthetic routes to a-dehydroamino acids and their deriva-
tives have been discovered,3 whereas there has been only
limited preliminary investigation of the photochemistry of
these dehydroamino acid derivatives.4 In this sense, the
photochemistry of substituted a-dehydroamino acids is an
unexplored ®eld of research. Accordingly, systematic study
is required to characterize the photochemical processes of
substituted a-dehydroamino acids.
In recent years, much attention has been devoted to the
synthetic application of excited-state processes initiated by
electron transfer &ET), owing to the fact that many photo-
2. Results and discussion
Keywords: amino acids and derivatives; photochemistry; electron transfer;
dihydrobenzoquinolinones; benzoisoquinolines.
Corresponding author. Tel.: 181-45-481-5661, ext. 3879; fax: 181-45-
491-7915; e-mail: sakurt01@kanagawa-u.ac.jp
2.1. Product distribution and composition in methanol
The starting &Z)-isomers 1a±k were prepared in good yields
p
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020&01)00477-X

5516
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
Scheme 2.
The ®nding that the photoproducts 2±4 are stable enough
such that they undergo only negligible decomposition under
the irradiation conditions employed &450 W high-pressure
Hg lamp; Pyrex glass ®lter; [&Z)-1]ˆ3.75£1023 mol dm23
1
reactions by means of H NMR spectroscopy, as typically
;
[TEA]ˆ0.10 mol dm23) made it possible to monitor the
by the ring-opening reactions of &Z)-1-naphthyl-substituted
oxazolones with primary amines.10 After a nitrogen-purged
MeOH solution of 1f &5.0£1023 mol dm23) containing TEA
&0.10 mol dm23) was irradiated with Pyrex-®ltered light
&.280 nm) from a 400 W high-pressure Hg lamp for 1.5 h
at room temperature, the product mixture obtained was
subjected to column chromatography over silica gel,
which allowed us to isolate the starting &Z)-1f &6%, isolated
yield), &E)-isomer of 1f &5%), substituted 1,2-dihydro-
benzo[f]quinolinone 2f &45%) and benzo[f]isoquinoline 3f
&14%). The structures of the isolated products were deter-
mined based on their spectroscopic and physical properties
and were con®rmed by the 1H±1H and 13C±1H COSY
shown in Table 1. The result obtained for &Z)-1f demon-
strates the rapid production of &E)-1f and the subsequent
increase in compositions for 2f±4f with the decrease of
&E)- and &Z)-isomer compositions, being consistent with
the mechanism in which these excited-state isomers serve
as precursors of these products. On the other hand, there was
no formation of the dihydrobenzoquinolinone derivative
2f when a nitrogen-purged MeOH solution of &Z)-1f
&6.6£1023 mol dm23) containing no TEA was irradiated
with Pyrex-®ltered light from a 450 W high-pressure Hg
lampfor 40 h & 1H NMR analysis), suggesting that ET
from TEA to the excited-state naphthylmethylene moiety
in 1f participates in the appearance of 2f as the primary
process. Instead, the benzo[f]quinolinone derivative 5f
was isolated as major product &22%) along with 3f &15%),
1
spectra of these products. A careful H NMR analysis of
the product mixture suggested the detectable formation of
the cis-1-azetine isomer 4f whose ring-proton signals with
the J3,4 value of 10.7 Hz were detected at 5.04 and
6.50 ppm,7c though attempts to isolate 4f from the mixture
were unsuccessful owing to its poor yield &Scheme 1). The
same product distribution was obtained by the irradiation of
other dehydronaphthylalanine derivatives 1a±e and 1g±i,
but 1j,k gave negligible amounts of dihydrobenzoquino-
linone derivatives.
1
&E)-1f &14%) and &Z)-1f &10%) &Scheme 2). A H NMR
analysis of the product mixture revealed that the presence
of unknown products makes it very dif®cult to detect proton
signals attributable to 4f. The structure of 5f was established
by measurements of its physical and spectroscopic para-
meters, as well as of its 2D NOESY spectrum in which
strong correlation was observed between the ring proton at
the 5-position, &the signal of which appears at 7.54 ppm),
and the protons of the butyl methylene group &giving their
signal at 4.50 ppm) attached to the ring nitrogen. It is likely
that molecular oxygen incorporated into gaseous nitrogen as
a contaminant is involved in the dehydrogenation of an
intermediate &formed via the excited-state &E)-isomer) to
eventually afford 5f. However, the fact that molecular
oxygen affects the reaction to only a negligible extent
requires further studies for elucidating the formation
mechanism of this quinolinone derivative.
On the other hand, the ¯uorescence of &Z)-1f &5.0£
1025 mol dm23) in nitrogen-saturated MeOH was quenched
by TEA &0.020±0.10 mol dm23; excitation wavelength,
280 nm) according to the Stern±Volmer equation, I0/Iˆ
114.5^0.5[TEA], where I and I0 refer to the ¯uorescence
intensities of 1f with and without TEA. It is evident from
a comparison of the UV absorption spectrum of TEA with
that of &Z)-1f that the ®rst singlet excitation energy of
the latter molecule is much lower than that of the former
and, hence, the ¯uorescence quenching observed is due to
ET but not due to singlet±singlet energy transfer. Unfortu-
nately, we could not determine the ¯uorescence lifetimes of
substituted naphthylalanines owing to their weak or very
weak emissions. Furthermore, it is well-known that the
photoinduced ET reactions of amine±aromatic systems
are thermodynamically favorable process and proceed
Scheme 1.
Table 1. Relation between irradiation time and composition &%) of each
compound obtained by the irradiation of &Z)-If in MeOH±TEA at room
temperature
Compound
Irradiation time &h)
1.5 2.0
100 60.7 43.5 34.2 27.3 18.0
0
0.5
1.0
3.0
4.0
9.3
5.0
&Z)-1f
&E)-1f
2f
3f
cis-4f
4.0
5.6
0
0
0
0
31.6 38.0 35.8 32.0 22.5 11.8
4.3 11.7 20.4 28.8 43.8 59.3 69.0
3.2
0.1
6.5
0.3
9.0 11.0 14.5 17.8 19.6
0.6 0.9 1.2 1.8 1.8

K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
5517
same results were obtained by the irradiation of a MeOD
solution of &Z)-1a having no alkyl substituent attached to the
amide nitrogen, as well as by the irradiation of deuteriated
1f in MeCN. Furthermore, a 1H NMR analysis of the
reaction mixture obtained by the irradiation of a CD3OD
solution of &Z)-1f &2.5£1022 mol dm23) containing TEA
and 1,4-dioxane &internal standard,
&0.10 mol dm23
)
0.10 mol dm23) for a given period of time showed no sign
of a change in this amine concentration during the
reaction. These ®ndings are consistent with our prediction,
thereby substantiating the mechanism proposed for the
formation of 2.
If the rate for the cyclization reaction from the excited-state
&E)-isomer via ET does not differ greatly from that for the
isomerization into the &Z)-isomer, Scheme 3 may allow us to
expect that the use of &E)-1f as the starting isomer enhances
Scheme 3.
Scheme 4.
ef®ciently to give mechanistically interesting products.1,6,8
Accordingly, these considerations &in addition to the
previous results7 and the fact that no 2f is formed without
TEA) lead us to propose Scheme 3 in which ET from the
ground-state TEA to the excited singlet-state &E)-isomer
forms the radical ion pair intermediate I, in competition
with the intramolecular cyclization of this isomer eventually
giving the 1-azetine derivative 4. Hydrogen transfer from
the amide nitrogen to the amide carbonyl oxygen within the
intermediate I and the subsequent back ET to TEA radical
cation affords 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.
the composition of 2f relative to that of 3f at the early stage
of the reaction. A nitrogen-purged MeOH solution of &E)-1f
&3.75£1023 mol dm23) was irradiated under the same condi-
tions as those for the irradiation of &Z)-1f and the results
obtained are shown in Table 2. A comparison of the compo-
sition of each compound given in Tables 1 and 2 &0.5 h
irradiation) reveals that the reaction starting from the
excited-state &E)-isomer increases signi®cantly the relative
composition of 2f [2f/3fˆ1.3 for &Z)-1f and 17.6 for &E)-1f]
and then the composition of 4f is also increased by a factor
of about 5. In addition, prolonged irradiation reduces the
difference in product composition between the &Z)- and
&E)-isomers. These ®ndings are in accord with our expecta-
tion and, hence, lead us to conclude that the isomerization is
not so fast as compared to the ET and cyclization processes
in which the excited-state &E)-isomer serves as a precursor
of dihydrobenzoquinolinone and 1-azetine derivatives. It is
According to Scheme 3, we predict that the N-alkyl amide
hydrogen in the starting 1 should migrate to the 2-position of
the benzoquinolinone ring upon forming 2, and that the
TEA concentration should remain constant during the
reaction. After the H±D exchange reaction for the amide
protons of &Z)-1f &3.75£1023 mol dm23) in MeOD±TEA
Table 2. Relation between irradiation time and composition &%) of each
compound obtained by the irradiation of &E)-If in MeOH±TEA at room
temperature
Compound
Irradiation time &h)
1.5 2.0
&0.10 mol dm23
)
was completed &12 h incubation),
0
0.5
1.0
3.0
4.0
5.0
deuteriated 1f was irradiated with Pyrex-®ltered light from
a 450 W high-pressure Hg lamp for 5.0 h at room tempera-
&Z)-1f
&E)-1f
2f
3f
cis-4f
0 26.9 30.6 27.4 21.7 12.7
100 56.0 40.2 31.4 25.5 15.6
6.1
8.1
1.8
2.6
1
ture. H NMR spectra of the product mixture in DMSO-d6,
0
0
0
15.8 25.8 35.4 44.6 60.2 71.7 80.1
obtained after usual work-up, clearly showed disappearance
of the 4.56 ppm signal which was ascribed to the proton
attached to the 2-position of the ring &Scheme 4). The
0.9
0.5
2.5
0.8
4.8
1.0
6.8
1.4
9.9 12.3 13.8
1.6 1.8 1.7

5518
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
Table 3. Substituent effects on the composition of each compound obtained by the irradiation of the strating &Z)-1 in MeOH containing TEA at room
temperature
Compound
Irradiation
time &h)
Composition &%)
&Z)-1
&E)-1
2
3
cis-4
trans-4
1a &RˆH)
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
0.5
5.0
1.0
9.0
1.0
9.0
59.1
2.2
71.3
1.4
69.8
4.1
67.9
5.7
65.5
8.9
60.7
4.0
61.9
1.8
56.8
3.7
35.7
3.4
22.9
1.7
25.1
4.9
27.0
7.3
31.3
14.2
31.6
5.6
32.4
3.5
34.7
4.4
35.5
9.8
3.9
76.3
4.0
85.0
3.0
74.5
2.8
68.4
0.0
43.3
4.3
69.0
3.2
70.8
5.7
69.2
2.5
0.7
13.0
1.8
11.0
2.1
14.9
2.2
17.4
3.2
26.2
3.2
19.6
2.5
20.8
2.9
21.6
2.1
0.6
5.2
0.0
0.9
0.0
1.5
0.0
1.2
0.0
5.8
0.1
1.8
0.0
3.1
0.0
1.2
0.0
3.7
0.7
10.3
0.0
9.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.7
6.2
0.0
1.3
1b &RˆMe)
1c &RˆEt)
1d &RˆPr)
1e &Rˆi-Pr)
1f &RˆBu)
1g &RˆPhCH2)
1h &Rˆ4-OMeC6H4CH2)
1i &Rˆ4-CF3C6H4CH2)
1j &Rˆt-Bu)
59.9
7.2
52.1
14.8
82.2
44.1
62.7
0.0
0.0
0.0
16.5
6.4
47.8
0.7
40.0
20.8
17.1
34.5
1k &RˆPh)
0.0
10.4
very likely that the &Z)-isomer radical anion generated by
ET from TEA reverts to the starting &Z)-1f through back
ET to the TEA radical cation, owing to the unfavorable
con®guration of this radical anion for the cyclization
reaction eventually affording 2f.
collected in Table 4. Interestingly, the selectivity of 2,
except 2a, decreases with an increse in steric bulkiness of
the substituent R: 2b.2c.2d 2f<2g<2h<2i 2e@2jˆ2k.
This decrease in selectivity is re¯ected in the enhanced
selectivity for substituted benzoisoquinolines &3) and
1-azetines &4), being consistent with the mechanism in
which ET to the excited-state &E)-1 occurs in competition
with both the cyclization giving eventually 4 and the
isomerization into &Z)-1, as shown in Scheme 3. In addition,
the introduction of bulky tert-butyl &1j) and phenyl &1k)
groups into 1 completely inhibits the appearance of
the corresponding benzoquinolinone derivative 2 &the
selectivity of 2 becomes zero). Because the ¯uorescence
of 1j &5.0£1025 mol dm23) is also quenched by TEA
2.2. Substituent effects on the product composition
In order to shed light on the scope and limitations of ET-
induced cyclization reactions in the synthesis of substituted
1,2-dihydrobenzo[f]quinolinones, we investigated sub-
stituent effects on the product composition obtained in
MeOH &Table 3). Table 3 clearly shows that both the
photoreactivities of the &Z)- and &E)-isomers have a
tendency to decrease with increasing steric bulkiness of
the alkyl substituent attached to the amide nitrogen
&RˆMe!i-Pr!t-Bu), whereas this increase in steric
bulkiness accelerates the isomerization into the &E)-isomer.
These ®ndings suggest that the introduction of sterically
bulky substituent at the ole®nic carbon of &Z)-1 enhances
the rate for deactivation of the excited-state &Z)-isomer
accompanying its isomerization. It should be also pointed
out here that the phenyl substituent in 1k substantially
lowers the excited-state reactivity of this naphthylalanine
derivative, and that the reactivity of 1g &RˆPhCH2) under-
goes electronic effects of the methoxy &1h) and tri¯uoro-
methyl &1i) groups to only a very small extent.
&I0/Iˆ113.0^0.4[TEA]; [TEA]ˆ0.020±0.10 mol dm23
;
excitation wavelength, 273 nm), ET from TEA to the
excited-state &E)-1j should take place giving the 1j radical
anion and TEA radical cation pair I &Scheme 3). Taking into
account that the enol-type biradical II may adopt an
approximately planar structure, it is reasonable to conclude
that the bulky tert-butyl and phenyl substituents exert their
Table 4. Substituent effects on the selectivity of each product obtained by
the irradiation of the starting &Z)-1
Compound
Selectivity &%)
2
3
cis-4
trans-4
1a
1b
1c
1d
1e
1f
1g
1h
1i
80.5
87.7
81.6
77.3
54.4
75.0
74.5
74.5
75.0
0.0
12.7
11.4
16.7
21.2
36.0
23.0
22.2
23.4
20.6
74.5
48.3
6.7
0.9
1.7
1.6
7.6
2.1
3.3
2.1
0.0
0.0
0.0
0.0
2.1
0.0
0.0
0.0
0.0
9.7
6.6
Because both the isomers are consumed completely by
much longer irradiation, we may de®ne a selectivity for
the dihydrobenzoquinolinone derivative 2 as the ratio of
composition for this derivative to the sum of product
composition, namely, 2/&21314) which is independent of
irradiation time. The selectivity of each product was
estimated by employing the compositions obtained at
three different irradiation times &3.0, 4.0 and 5.0 h for
1a±i; 5.0, 7.0 and 9.0 h for 1j,k) and its average value is
4.3
15.8
45.1
1j
1k
0.0

K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
5519
Table 5. Relation between irradiation time and composition &%) of each
compound obtained by the irradiation of &Z)-If in MeCN±TEA at room
temperature
MeOH, than in the aprotic polar solvent, MeCN, being not
consistent with our expectation. Additionally, the latter
solvent lowers not only the relative rate for the Z!E
isomerization &0.5 h irradiation) but also the selectivity of
2f &75.0!69.4%, average values). Similar results were
obtained with &Z)-1a &RˆH) and &Z)-1g &RˆPhCH2).
These observations cannot be explained in terms of the
disappearance of hydrogen-bonding solvation of TEA in
MeCN. Since the amide carbonyl oxygen has been found
to readily forms a hydrogen bond to a protic solvent
molecule,12 we examined solvent effects on the UV
absorption &[&Z)-1f]ˆ5.0£1025 mol dm23), ¯uorescence
Compound
Irradiation time &h)
1.5 2.0
100 77.4 70.0 65.0 60.6 53.1 44.6 38.0
0
0.5
1.0
3.0
4.0
5.0
&Z)-1f
&E)-1f
2f
0
0
0
0
20.1 24.3 26.2 27.5 27.8 28.1 26.3
1.6
0.9
0.0
3.6
2.0
0.0
5.8
3.1
0.0
8.1 12.7 19.3 25.3
3f
cis-4f
3.9
0.0
6.3
0.0
8.0 10.5
0.0 0.0
&5.0£1025 mol dm23) and 13C NMR &1.0£1022 mol dm23
)
great steric effects on the coupling process of II so as to
completely inhibit this process. This conclusion is substan-
tiated by MM2 calculations of 2f and 2j &which demonstrate
that the replacement of butyl group by tert-butyl as the
substituent R results in a great destabilization of the former
dihydrobenzoquinolinone derivative &57.6 kJ mol21)) and,
thus, provides a piece of evidence for the mechanism
shown in Scheme 3. There were negligible products other
than &E)-1, 3 and 4 in the reaction mixtures obtained by the
irradition of 1j and 1k in the presence of TEA &1H NMR
analysis). This observation suggests that on prevention of
the cyclization of II affording 2 via III, the intermediate II
eventually reverts to the &E)-isomer. On the other hand,
contrary to our expectation the starting 1a having no
N-alkyl substituent afforded 2a in lower selectivity than
that of 2b &Table 4). The ®nding that the selectivity of 4a
is much larger than that of 4b con®rms that the substitution
of hydrogen for the methyl grouplowers the relative rate of
ET from TEA to the excited-state &E)-isomer, probably
owing to the decreased reactivity of the intermediate I
toward intramolecular hydrogen transfer &Scheme 3).
spectra of &Z)-1f in order to obtain evidence for the
hydrogen-bonding solvation of this dehydronaphthylalanine
derivative in the ground and excited singlet states &Table 6).
The spectroscopic data obtained clearly show that the
alteration in solvent from MeCN to MeOH causes a
negligible shift of the ®rst absorption band with an increase
in its molar absorption coef®cient, while in the latter solvent
the ¯uorescence intensity is enhanced with no shift of the
emission maximum. Because MeCN and MeOH have
almost the same polarity &Table 6), these observations
strongly suggest the occurrence of the hydrogen-bonding
solvation of 1f by the latter protic solvent in both the ground
state and the excited singlet state. Interestingly, the amide
carbonyl carbon signal of the starting 1f was subject to a
down®eld shift &0.8±1.2 ppm) on changing the solvent from
CD3CN to CD3OD, thus providing additional proof for the
formation of hydrogen bonds in the ground state. It is, thus,
very likely that the solvation of the excited singlet-state 1f
by MeOH accelerates the Z!E isomerization and then
greatly enhances the electron-accepting ability of the
naphthylmethylene moiety.
The ¯uorescence of &Z)-1f &5.0£1025 mol dm23) was
quenched by TEA &0.020±0.10 mol dm23; excitation wave-
length, 283 nm) according to the equation, I0/Iˆ112.8^
0.2[TEA], in MeCN. A comparison with the emission
quenching in MeOH demonstrates that the quenching
constant &4.5^0.5) in this protic solvent is larger than that
in MeCN. If we are allowed to assume that the ¯uorescence
lifetime of 1f in the former solvent is not much different
from that in the latter,8 the result shown above &in addition
to the fact that MeOH forms a hydrogen bond to TEA to
lower the effective concentration of this amine) sub-
stantiates the enhanced electron-accepting ability of the
excited singlet-state 1f in MeOH.
2.3. Solvent effects on the product composition
It was previously shown that ET from the tertiary amino
nitrogen takes place more ef®ciently in MeCN than in
MeOH because of the formation of hydrogen bonding in
the latter solvent.8,11 Thus, we may expect the enhancement
of both the photoreactivity of &Z)-1 and the selectivity of the
dihydrobenzoquinolinone derivative 2. In Table 5 are shown
compositions of 1f±4f obtained by the irradiation of &Z)-1f
&3.75£1023 mol dm23
)
in MeCN containing TEA
&0.10 mol dm23) under the same conditions. A comparison
of Tables 1 and 5 reveals that the excited-state reactivities of
both isomers are much higher in the protic polar solvent,
Table 6. Solvent effects on the spectroscopic parameters of &Z)-1f at room temperature
Solvent
UV
emaxb &dm3 mol21 cm21
Fluorescence
lf,maxc &nm)
13C NMR
d
lmaxa &nm)
)
If,max
d&±CONH±) &ppm)
MeCN &35.94)e
MeOH &32.66)e
CD3CN
309
309
12 300
13 300
373 &lexˆ280 nm)f
373 &lexˆ280 nm)f
25.1
37.4
165.6, 170.8
166.4, 172.0
CD3OD
a
UV absorption maximum.
Molar absorption coef®cient.
Fluorescence maximum.
Fluorescence intensity.
Relative permittivity at 258C &see Ref. 15).
Excitation wavelength.
b
c
d
e
f

5520
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
3. Conclusions
8.24 &1H, d, Jˆ8.6 Hz), 8.75 &1H, d, Jˆ7.3 Hz). 13C NMR
&125.7 MHz, CDCl3): d 15.8, 122.8, 125.7, 126.3, 127.1,
127.4, 128.9, 129.1, 131.4, 131.8, 132.3, 133.3, 133.6,
166.8, 167.8.
Although there are many synthetic routes to medium-sized
lactams fused to an aromatic ring,13 convenient photo-
chemical routes to substituted dihydrobenzoquinolinones
are scarcely known.14 The procedure for preparing the
starting 1 is very simple and is easily applicable to its related
compounds. Taking into consideration the fact that the
dihydrobenzoquinolinone derivative 2 obtained is photo-
chemically very stable, we were led to conclude that the
photoreaction of substituted a-dehydro&1-naphthyl)alanine
having an N-alkyl group&that is not so much bulky) in
MeOH containing TEA presents a new method for
constructing the dihydrobenzoquinolinone skeleton. We
were also able to obtain signi®cant information regarding
the mechanism for the ET-initiated photocyclization
reaction of 1, through analyses of the product compositions
&derived from the starting &Z)-1, &E)-1f and deuteriated
&Z)-1a,f), as well as of substituent and solvent effects on
both the photoreactivities of 1 and the selectivities of the
products 2±4.
4.3. General procedure for the synthesis of ꢀZ)-2-acetyl-
amino-3-ꢀ1-naphthyl)-2-propenamide [ꢀZ)-1a], ꢀZ)-2-
acetylamino-N-alkyl-3-ꢀ1-naphthyl)-2-propenamides
[ꢀZ)-1b±j] and ꢀZ)-2-acetylamino-3-ꢀ1-naphthyl)-N-
phenyl-2-propenamide [ꢀZ)-1k]
&Z)-2-Methyl-4-&1-naphthylmethylene)-5&4H)-oxazolone
&0.020 mol) was added to dry CHCl3 &200 mL) containing
primary amine &0.021 mol) and the resulting solution was
re¯uxed for 0.5±1.5 h. The reaction mixture was concen-
trated to dryness and the resulting residue was dissolved in
EtOH &50 mL) and then treated with activated charcoal
powder. After removal of the solvent under reduced pres-
sure, the crystalline solid obtained was recrystallized twice
from EtOH±hexane affording colorless crystals &40±60%).
4.3.1. ꢀZ)-2-Acetylamino-3-ꢀ1-naphthyl)-2-propenamide
[ꢀZ)-1a]. Mp192.0±194.0 8C. IR &KBr): 3364, 3264, 3210,
1
1647, 1610 cm21. H NMR &500 MHz, DMSO-d6): d 1.84
4. Experimental
4.1. General
&3H, s,), 7.24 &1H, s), 7.51±7.59 &6H, m), 7.90 &1H, d,
Jˆ8.2 Hz), 7.94±7.99 &2H, m), 9.22 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 22.6, 124.1, 124.3, 125.4,
125.9, 126.2, 126.3, 128.3, 128.4, 131.0, 131.3, 132.4,
133.1, 166.5, 169.3. Anal. calcd &found) for C15H14N2O2:
C, 70.85 &70.82); H, 5.55 &5.17); N, 11.02% &10.91%).
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. UV
absorption spectra were recorded on a Shimadzu UV-2200
spectrophotometer. A cell with a 10-mm pathlength was
used. The ¯uorescence spectra of &Z)-1 at room temperature
were measured in the presence and absence of TEA under
nitrogen with a Shimadzu RF-5000 spectro¯uorimeter.
Elemental analyses were performed on a Perkin±Elmer
PE2400 series II CHNS/O analyzer. MeOH and MeCN
were puri®ed according to the standard procedures and
freshly distilled prior to use.15 TEA was fractionally
distilled from sodium hydroxide. All other reagents used
were obtained from commercial sources and were of the
highest grade available. MM2 calculations were accom-
plished by using the Mac spartan Plus available from
Wavefunction, Inc.
4.3.2. ꢀZ)-2-Acetylamino-N-methyl-3-ꢀ1-naphthyl)-2-pro-
penamide [ꢀZ)-1b]. Mp190.0±190.5 8C. IR &KBr): 3340,
.
3236, 3180, 1644, 1628 cm21 1H NMR &500 MHz,
DMSO-d6): d 1.84 &3H, s), 2.72 &3H, d, Jˆ4.6 Hz), 7.51±
7.58 &5H, m), 7.90 &1H, d, Jˆ8.3 Hz), 7.94±7.98 &2H, m),
8.04 &1H, q, Jˆ4.6 Hz), 9.24 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 22.7, 26.2, 124.16, 124.23, 125.5, 126.0,
126.2, 126.3, 128.3, 128.4, 131.1, 131.3, 132.5, 133.2,
165.2, 169.5. Anal. calcd &found) for C16H16N2O2: C,
71.62 &71.49); H, 6.01 &5.73); N, 10.44% &10.31%).
4.3.3. ꢀZ)-2-Acetylamino-N-ethyl-3-ꢀ1-naphthyl)-2-pro-
penamide [ꢀZ)-1c]. Mp182.0±183.0 8C. IR &KBr): 3310,
.
3240, 3180, 1656, 1623 cm21 1H NMR &500 MHz,
DMSO-d6): d 1.10 &3H, t, Jˆ7.3 Hz), 1.84 &3H, s), 3.22
&2H, dt, Jˆ7.3, 7.3 Hz), 7.49 &1H, s), 7.50±7.58 &4H, m),
7.90 &1H, d, Jˆ7.9 Hz), 7.94±7.98 &2H, m), 8.10 &1H, t,
Jˆ7.3 Hz), 9.22 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 14.7, 22.7, 34.0, 123.9, 124.2, 125.4, 126.0, 126.2,
126.3, 128.3, 128.4, 131.0, 131.4, 132.7, 133.2, 164.5,
169.4. Anal. calcd &found) for C17H18N2O2: C, 72.32
&71.97); H, 6.43 &6.30); N, 9.92% &9.83%).
4.2. General procedure for the synthesis of ꢀZ)-2-methyl-
4-ꢀ1-naphthylmethylene)-5ꢀ4H)-oxazolone
N-Acetylglycine &30.0 g, 0.26 mol), 1-naphthaldehyde
&48.4 g, 0.31 mol) and sodium acetate &16.0 g, 0.20 mol)
were added to acetic anhydride &150 mL) and the resulting
mixture was heated at 80±858C for 6±7 h with stirring. The
mixture was cooled with ice and the solid separated out was
collected by ®ltration with suction and washed with water,
small amounts of cold EtOH and then with dry hexane.
After the crude product had been air-dried at room tempera-
ture, it was recrystallized from hexane±CHCl3 to give
yellow crystals &24.4 g, 40%). Mp159.0±160.0 8C. IR
4.3.4. ꢀZ)-2-Acetylamino-3-ꢀ1-naphthyl)-N-propyl-2-pro-
penamide [ꢀZ)-1d]. Mp170.0±171.0 8C. IR &KBr): 3304,
.
3240, 3160, 1650, 1628 cm21 1H NMR &500 MHz,
DMSO-d6): d 0.90 &3H, t, Jˆ7.3 Hz), 1.51 &2H, m), 1.84
&3H, s), 3.13±3.18 &2H, m), 7.48 &1H, s), 7.51±7.59 &4H, m),
7.90 &1H, d, Jˆ7.9 Hz), 7.94±7.98 &2H, m), 8.08 &1H, t,
Jˆ6.7 Hz), 9.21 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 11.3, 22.3, 22.6, 40.8, 123.7, 124.1, 125.4, 125.9,
126.16, 126.24, 128.2, 128.4, 131.0, 131.3, 132.7, 133.1,
&KBr): 1760, 1650, 1260 cm21 1H NMR &500 MHz,
.
CDCl3): d 2.43 &3H, s), 7.54 &1H, dd, Jˆ7.3, 7.9 Hz), 7.58
&1H, dd, Jˆ7.3, 8.6 Hz), 7.61 &1H, dd, Jˆ7.3, 8.6 Hz), 7.88
&1H, d, Jˆ7.9 Hz), 7.93 &1H, d, Jˆ8.6 Hz), 8.02 &1H, s),

K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
5521
164.6, 169.3. Anal. calcd &found) for C18H20N2O2: C, 72.95
&73.01); H, 6.80 &6.57); N, 9.45% &9.44%).
q, Jˆ272 Hz), 124.5, 125.0 &2C, q, Jˆ4 Hz), 125.5, 126.0,
126.4 &2C), 127.3 &1C, q, Jˆ31 Hz), 127.8 &2C), 128.4 &2C),
131.0, 131.2, 132.5, 133.2, 144.7, 165.1, 169.8. Anal. calcd
&found) for C23H19F3N2O2: C, 66.98 &66.89); H, 4.64 &4.21);
N, 6.79% &6.83%).
4.3.5. ꢀZ)-2-Acetylamino-N-isopropyl-3-ꢀ1-naphthyl)-2-
propenamide [ꢀZ)-1e]. Mp201.5±202.5 8C. IR &KBr):
3334, 3270, 3214, 3160, 1650, 1623 cm21 1H NMR
.
4.3.10. ꢀZ)-2-Acetylamino-N-ꢀtert-butyl)-3-ꢀ1-naphthyl)-
2-propenamide [ꢀZ)-1j]. Mp181.0±182.0 8C. IR &KBr):
&500 MHz, DMSO-d6): d 1.15 &6H, d, Jˆ6.1 Hz), 1.83
&3H, s), 3.98±4.05 &1H, m), 7.39 &1H, s), 7.51±7.58 &4H,
m), 7.85 &1H, d, Jˆ7.9 Hz), 7.86 &1H, d, Jˆ7.9 Hz), 7.89±
7.98 &2H, m), 9.18 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 22.2 &2C), 22.7, 40.9, 123.1, 124.3, 125.5, 126.0,
126.3 &2C), 128.2, 128.4, 131.0, 131.5, 133.0, 133.2,
164.0, 169.2. Anal. calcd &found) for C18H20N2O2: C,
72.95 &72.84); H, 6.80 &6.48); N, 9.45% &9.50%).
1
3250, 1647, 1625 cm21. H NMR &500 MHz, DMSO-d6):
d 1.36 &9H, s), 1.82 &3H, s), 7.32 &1H, s), 7.37 &1H, s),
7.50±7.57 &4H, m), 7.89 &1H, d, Jˆ7.9 Hz), 7.93±7.98
&2H, m), 9.18 &1H, s). 13C NMR &125.7 MHz, DMSO-d6):
d 22.6, 28.5 &3C), 50.5, 122.6, 124.4, 125.5, 126.0, 126.2
&2C), 128.1, 128.4, 131.0, 131.6, 133.2, 133.5, 164.5, 169.0.
Anal. calcd &found) for C19H22N2O2: C, 73.52 &73.51); H,
7.14 &6.97); N, 9.03% &9.00%).
4.3.6. ꢀZ)-2-Acetylamino-N-butyl-3-ꢀ1-naphthyl)-2-pro-
penamide [ꢀZ)-1f]. Mp187.0±188.5 8C. IR &KBr): 3306,
3226, 3156, 1660, 1625 cm21
.
1H NMR &500 MHz,
4.3.11. ꢀZ)-2-Acetylamino-3-ꢀ1-naphthyl)-N-phenyl-2-
propenamide [ꢀZ)-1k]. Mp214.0±214.5 8C. IR &KBr):
DMSO-d6): d 0.90 &3H, t, Jˆ7.3 Hz), 1.33 &2H, tq, Jˆ7.3,
7.6 Hz), 1.48 &2H, tt, Jˆ6.7, 7.6 Hz), 1.83 &3H, s), 3.17 &2H,
dt, Jˆ6.4, 6.7 Hz), 7.46 &1H, s), 7.50±7.57 &4H, m), 7.89
&1H, d, Jˆ7.9 Hz), 7.93±7.96 &2H, m), 8.06 &1H, t,
Jˆ6.4 Hz), 9.20 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 13.7, 19.5, 22.6, 31.2, 38.8, 123.7, 124.1, 125.4,
125.9, 126.2 &2C), 128.2, 128.3, 131.0, 131.3, 132.7,
133.1, 164.6, 169.3. Anal. calcd &found) for C19H22N2O2:
C, 73.52 &73.54); H, 7.14 &7.02); N, 9.03% &9.13%).
1
3256, 1659, 1640 cm21. H NMR &500 MHz, DMSO-d6):
d 1.89 &3H, s), 7.09 &1H, dd, Jˆ7.3, 7.6 Hz), 7.34 &2H,
dd, Jˆ7.6, 8.2 Hz), 7.42 &1H, s), 7.54±7.58 &3H, m), 7.67
&1H, d, Jˆ7.3 Hz), 7.76 &2H, d, Jˆ7.6 Hz), 7.93 &1H, d,
Jˆ8.2 Hz), 7.96±7.99 &1H, m), 8.04±8.06 &1H, m), 9.44
&1H, s), 10.08 &1H, s). 13C NMR &125.7 MHz, DMSO-d6):
d 22.5, 120.1 &2C), 122.9, 123.4, 124.4, 125.5, 126.1, 126.4,
126.7, 128.5 &2C), 131.0, 131.2, 133.3, 133.4, 139.3, 164.0,
169.5. Anal. calcd &found) for C21H18N2O2: C, 76.34
&76.14); H, 5.49 &5.39); N, 8.48% &8.61%).
4.3.7. ꢀZ)-2-Acetylamino-N-benzyl-3-ꢀ1-naphthyl)-2-pro-
penamide [ꢀZ)-1g]. Mp185.0±186.5 8C. IR &KBr): 3280,
1
3230, 1650, 1630 cm21. H NMR &500 MHz, DMSO-d6):
4.4. General procedure for the irradiation of ꢀZ)-1a±k
d 1.86 &3H, s), 4.43 &2H, d, Jˆ6.1 Hz), 7.24 &1H, dd,
Jˆ6.7, 7.3 Hz), 7.23±7.32 &4H, m), 7.52±7.62 &5H, m),
7.91 &1H, d, Jˆ7.9 Hz), 7.91±7.95 &2H, m), 8.69 &1H, t,
Jˆ6.1 Hz), 9.31 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 22.6, 42.5, 124.1, 124.4, 125.4, 126.0, 126.2, 126.3,
126.5, 127.0 &2C), 128.0 &2C), 128.4 &2C), 131.0, 131.2,
132.5, 133.1, 139.6, 164.8, 169.6. Anal. calcd &found) for
C22H20N2O2: C, 76.72 &76.42); H, 5.85 &5.75); N, 8.13%
&7.92%).
In order to examine the irradiation time dependence of the
product distribution and composition, a MeOH solution
&45 mL) of &Z)-1 &3.75£1023 mol dm23) containing TEA
&0.10 mol dm23), placed in a Pyrex vessel, was irradiated
under nitrogen at room temperature with Pyrex-®ltered light
from a 450 W high-pressure Hg lamp. At suitable time inter-
vals, an aliquot &5 mL) of the solution was pipetted off and
concentrated to dryness in vacuo. The resulting residue was
1
dissolved in DMSO-d6 and subjected to H NMR analysis.
The composition was estimated from the area ratio of a
4.3.8.
naphthyl)-2-propenamide [ꢀZ)-1h]. Mp175.5±177.5 8C.
IR &KBr): 3304, 3270, 1650, 1626 cm21 1H NMR
ꢀZ)-2-Acetylamino-N-ꢀ4-methoxybenzyl)-3-ꢀ1-
1
2
given H NMR signal for each compound. For the H &D)
tracer experiment a MeOD solution &45 mL) of &Z)-1a or
&Z)-1f &3.75£1023 mol dm23) was allowed to stand for 12 h
in the presence of TEA &0.10 mol dm23) and then irradiated
for 5.0 h with Pyrex-®ltered light under an atmosphere of
prepuri®ed nitrogen. After 5.0 h irradiation, an aliquot
&5 mL) of the solution was pipetted off and concentrated
to dryness in vacuo. The resulting residue was dissolved
in DMSO-d6 and subjected to 1H NMR analysis. The
remaining solution of &Z)-1a was concentrated to dryness
in vacuo and the resulting crystalline solid was washed
several times with MeOH in order to obtain the analytical-
grade deuteriated 2a from the reaction mixture.
.
&500 MHz, DMSO-d6): d 1.85 &3H, s), 3.74 &3H, s), 4.35
&2H, d, Jˆ6.1 Hz), 6.89 &2H, d, Jˆ8.6 Hz), 7.29 &2H, d,
Jˆ8.6 Hz), 7.51±7.57 &4H, m), 7.60 &1H, d, Jˆ7.3 Hz),
7.91 &1H, d, Jˆ7.9 Hz), 7.95±7.98 &2H, m), 8.62 &1H, t,
Jˆ6.1 Hz), 9.28 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 22.6, 41.9, 55.0, 113.5 &3C), 124.1, 124.4, 125.4,
125.9, 126.2, 126.3, 128.4 &3C), 131.0, 131.3, 131.6,
132.5, 133.1, 158.0, 164.7, 169.5. Anal. calcd &found) for
C23H22N2O3: C, 73.78 &73.65); H, 5.92 &5.72); N, 7.48%
&7.35%).
4.3.9. ꢀZ)-2-Acetylamino-3-ꢀ1-naphthyl)-N-[4-ꢀtri¯uoro-
methyl)benzyl]-2-propenamide [ꢀZ)-1i]. Mp201.5±
On the other hand, a solution &500 mL) of &Z)-1a±k
202.58C. IR &KBr): 3298, 3208, 3150, 1647, 1629 cm21
.
&5.0£1023 mol dm23
)
in MeOH containing TEA
1H NMR &500 MHz, DMSO-d6): d 1.87 &3H, s), 4.50 &2H,
d, Jˆ5.5 Hz), 7.60 &2H, d, Jˆ7.9 Hz), 7.53±7.62 &5H, m),
7.70 &2H, d, Jˆ7.9 Hz), 7.92 &1H, d, Jˆ7.9 Hz), 7.95±7.99
&2H, m), 8.78 &1H, t, Jˆ5.5 Hz), 9.35 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 22.6, 42.3, 124.2, 124.4 &1C,
&0.10 mol dm23), placed in a Pyrex vessel, was irradiated
for a given period of time under nitrogen with Pyrex-®ltered
light from a 400 W high-pressure Hg lamp at room tempera-
ture. After 1.5 h &1a±i) or 8 h &1j,k) irradiation, an appro-
priate amount of the solution &5 mL) being irradiated was

5522
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
pipetted off and concentrated to dryness in vacuo giving the
residue which was subjected to 1H NMR analysis in DMSO-
d6. The remaining solutions of 1b±g and 1i±k were concen-
trated to dryness under reduced pressure and the resulting
residues were subjected to column chromatography over
silica gel &230 mesh, Merck) eluting with EtOAc±hexane.
The crystalline residues derived from 1a and 1h were
washed with small amounts of MeOH and then recrystal-
lized from EtOH, allowing us to obtain analytical-grade 2a
and 2h. The combined ®ltrates were concentrated to dryness
and subjected to column chromatography in the same
manner as above. 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±k], 1,2-dihydrobenzo[f]quino-
linones &2a±i), benzo[f]isoquinolines &3a±k) and 1-azetines
&4j,k) are as follows.
112.5, 124.6, 125.3, 125.6, 125.8, 125.9, 127.1, 128.2,
131.2, 132.6, 133.1, 135.1, 164.4, 168.5. Anal. calcd
&found) for C18H20N2O2: C, 72.95 &73.14); H, 6.80 &6.83);
N, 9.45% &9.20%).
4.4.5. ꢀE)-1e. Mp185.0±186.0 8C. IR &KBr): 3274, 1639,
1
1629 cm21. H NMR &500 MHz, DMSO-d6): d 0.77 &6H,
d, Jˆ6.7 Hz), 2.03 &3H, s), 3.77 &1H, dq, Jˆ6.7, 7.9 Hz),
7.39 &1H, dd, Jˆ7.3, 7.9 Hz), 7.42 &1H, d, Jˆ7.3 Hz), 7.50
&1H, s), 7.53 &1H, dd, Jˆ7.3, 7.7 Hz), 7.55 &1H, dd, Jˆ7.7,
7.9 Hz), 7.59 &1H, d, Jˆ7.9 Hz), 7.79 &1H, d, Jˆ7.3 Hz),
7.90 &1H, d, Jˆ7.9 Hz), 8.00 &1H, d, Jˆ7.9 Hz), 9.68 &1H,
s). 13C NMR &125.7 MHz, DMSO-d6): d 21.4 &2C), 23.5,
40.2, 112.0, 124.5, 125.1, 125.5, 125.7, 125.8, 127.0, 128.1,
131.2, 132.4, 133.0, 135.1, 163.3, 168.5. Anal. calcd &found)
for C18H20N2O2: C, 72.95 &72.53); H, 6.80 &6.66); N, 9.45%
&9.45%).
4.4.1. ꢀE)-1a. Mp199.5±201.0 8C. IR &KBr): 3334, 3250,
4.4.6. ꢀE)-1f. Mp148.0±149.0 8C. IR &KBr): 3250, 1650,
1
1
3166, 1653, 1610 cm21. H NMR &500 MHz, DMSO-d6):
1629 cm21. H NMR &500 MHz, DMSO-d6): d 0.66 &3H,
d 2.03 &3H, s,), 7.16 &1H, br s), 7.28 &1H, br s), 7.42 &1H,
s), 7.42 &1H, dd, Jˆ6.7, 7.3 Hz), 7.49 &1H, d, Jˆ6.7 Hz),
7.51±7.56 &2H, m), 7.80 &1H, d, Jˆ7.9 Hz), 7.91 &1H, d,
Jˆ7.9 Hz), 7.99 &1H, d, Jˆ7.9 Hz), 9.69 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 23.4, 112.8, 124.5, 125.3, 125.6,
125.7, 125.9, 127.0, 128.1, 131.2, 132.7, 133.0, 134.7,
166.2, 168.5. Anal. calcd &found) for C15H14N2O2: C,
70.85 &70.55); H, 5.55 &5.52); N, 11.02% &10.85%).
t, Jˆ7.3 Hz), 0.88 &2H, tq, Jˆ7.3, 7.6 Hz), 1.06 &2H, tt,
Jˆ7.0, 7.3 Hz), 2.00 &3H, s), 2.87 &2H, dt, Jˆ6.1, 7.0 Hz),
7.36±7.40 &2H, m), 7.43 &1H, s), 7.49±7.57 &2H, m), 7.75
&1H, t, Jˆ6.1 Hz), 7.77±7.79 &1H, m), 7.89 &1H, d,
Jˆ7.3 Hz), 7.98 &1H, d, Jˆ7.6 Hz), 9.69 &1H, s). 13C
NMR &125.7 MHz, DMSO-d6): d 13.6, 19.4, 23.5, 30.3,
38.3, 112.6, 124.6, 125.3, 125.6, 125.8, 126.0, 127.1,
128.2, 131.3, 132.6, 133.1, 135.1, 164.4, 168.6. EI-MS:
m/z &%) 310 &M1, 13.62). Anal. calcd &found) for
C19H22N2O2: C, 73.52 &73.29); H, 7.14 &7.19); N, 9.03%
&9.14%).
4.4.2. ꢀE)-1b. Mp167.5±168.5 8C. IR &KBr): 3268, 1626,
1
1615 cm21. H NMR &500 MHz, DMSO-d6): d 2.02 &3H,
s), 2.43 &3H, d, Jˆ4.9 Hz), 7.36 &1H, d, Jˆ6.7 Hz), 7.42
&1H, dd, Jˆ6.7, 7.3 Hz), 7.44 &1H, s), 7.53 &1H, dd,
Jˆ6.7, 7.3 Hz), 7.56 &1H, dd, Jˆ6.7, 7.3 Hz), 7.78 &1H, q,
Jˆ4.9 Hz), 7.79 &1H, d, Jˆ7.3 Hz), 7.91 &1H, d, Jˆ7.3 Hz),
8.00 &1H, d, Jˆ7.3 Hz), 9.75 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 23.5, 25.7, 112.9, 124.4, 125.2, 125.4, 125.8,
126.0, 127.1, 128.3, 131.2, 132.5, 133.1, 134.7, 165.1,
168.6. Anal. calcd &found) for C16H16N2O2: C, 71.62
&71.50); H, 6.01 &6.01); N, 10.44% &10.32%).
4.4.7. ꢀE)-1g. Mp152.0±153.0 8C. IR &KBr): 3280, 1690,
1
1680 cm21. H NMR &500 MHz, DMSO-d6): d 2.04 &3H,
s), 4.13 &2H, d, Jˆ6.1 Hz), 6.90 &2H, d, Jˆ7.3 Hz), 7.12±
7.13 &3H, m), 7.29 &1H, dd, Jˆ7.3, 7.9 Hz), 7.34 &1H, d,
Jˆ7.3 Hz), 7.41 &1H, s), 7.51±7.55 &2H, m), 7.80 &1H, d,
Jˆ7.9 Hz), 7.92 &1H, d, Jˆ6.8 Hz), 8.00 &1H, d, Jˆ6.9 Hz),
8.37 &1H, t, Jˆ6.1 Hz), 9.80 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 23.3, 42.1, 113.1, 124.6, 125.3, 125.67,
125.74, 125.9, 126.3, 127.0, 127.1 &2C), 127.8 &2C),
128.1, 131.2, 132.4, 133.0, 134.8, 138.6, 164.6, 168.4.
Anal. calcd &found) for C22H20N2O2: C, 76.72 &76.77); H,
5.85 &5.87); N, 8.13% &8.10%).
4.4.3. ꢀE)-1c. Mp157.0±158.0 8C. IR &KBr): 3256, 1624,
1
1612 cm21. H NMR &500 MHz, DMSO-d6): d 0.72 &3H,
t, Jˆ7.3 Hz), 2.02 &3H, s), 2.93 &2H, dq, Jˆ6.5, 7.3 Hz),
7.40±7.41 &2H, m), 7.48 &1H, s), 7.52 &1H, dd, Jˆ6.7,
6.7 Hz), 7.55 &1H, dd, Jˆ6.7, 7.9 Hz), 7.77 &1H, t,
Jˆ6.5 Hz), 7.79±7.81 &1H, m), 7.91 &1H, d, Jˆ6.7 Hz),
8.00 &1H, d, Jˆ7.9 Hz), 9.71 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 13.6, 23.5, 33.3, 112.5, 124.5,
125.3, 125.6, 125.8, 125.9, 127.1, 128.2, 131.2, 132.5,
133.1, 135.1, 164.2, 168.6. Anal. calcd &found) for
C17H18N2O2: C, 72.32 &72.61); H, 6.43 &6.41); N, 9.92%
&10.21%).
4.4.8. ꢀE)-1h. Mp131.0±131.5 8C. IR &KBr): 3292, 1636,
1
1626 cm21. H NMR &500 MHz, DMSO-d6): d 2.03 &3H,
s), 3.70 &3H, s), 4.07 &2H, d, Jˆ6.1 Hz), 6.69 &2H, d,
Jˆ8.5 Hz), 6.85 &2H, d, Jˆ8.5 Hz), 7.29 &1H, dd, Jˆ6.7,
7.9 Hz), 7.33 &1H, d, Jˆ6.7 Hz), 7.41 &1H, s), 7.51±7.55
&2H, m), 7.80 &1H, d, Jˆ7.9 Hz), 7.92 &1H, d, Jˆ6.7 Hz),
8.00 &1H, d, Jˆ6.7 Hz), 8.29 &1H, t, Jˆ6.1 Hz), 9.78 &1H, s).
13C NMR &125.7 MHz, DMSO-d6): d 23.4, 41.7, 55.0, 113.3
&3C), 124.6, 125.4, 125.7, 125.8, 125.9, 127.1, 128.2, 128.5
&2C), 130.5, 131.3, 132.4, 133.1, 134.8, 158.0, 164.5, 168.5.
Anal. calcd &found) for C23H22N2O3: C, 73.78 &73.72); H,
5.92 &5.91); N, 7.48% &7.31%).
4.4.4. ꢀE)-1d. Mp157.0±158.5 8C. IR &KBr): 3252, 1630,
1
1620 cm21. H NMR &500 MHz, DMSO-d6): d 0.53 &3H,
t, Jˆ7.3 Hz), 1.13 &2H, tq, Jˆ6.7, 7.3 Hz), 2.02 &3H, s),
2.85 &2H, dt, Jˆ6.1, 6.7 Hz), 7.39 &1H, dd, Jˆ6.2,
7.3 Hz), 7.39 &1H, d, Jˆ6.2 Hz), 7.46 &1H, s), 7.52 &1H,
dd, Jˆ6.7, 7.3 Hz), 7.55 &1H, dd, Jˆ6.7, 7.9 Hz), 7.79
&1H, d, Jˆ7.3 Hz), 7.80 &1H, t, Jˆ6.1 Hz), 7.91 &1H, d,
Jˆ7.3 Hz), 8.00 &1H, d, Jˆ7.9 Hz), 9.70 &1H, s). 13C
NMR &125.7 MHz, DMSO-d6): d 11.2, 21.4, 23.5, 40.5,
4.4.9. ꢀE)-1i. Mp158.0±159.0 8C. IR &KBr): 3286, 1640,
1
1632 cm21. H NMR &500 MHz, DMSO-d6): d 2.04 &3H,
s), 4.20 &2H, d, Jˆ6.1 Hz), 7.13 &2H, d, Jˆ8.6 Hz), 7.28
&1H, dd, Jˆ7.3, 7.9 Hz), 7.31 &1H, d, Jˆ7.3 Hz), 7.35
&1H, s), 7.46 &2H, d, Jˆ8.6 Hz), 7.51±7.56 &2H, m), 7.80

K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
5523
&1H, d, Jˆ7.9 Hz), 7.92 &1H, d, Jˆ7.6 Hz), 8.01 &1H, d,
Jˆ7.3 Hz), 8.44 &1H, t, Jˆ6.1 Hz), 9.86 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 23.2, 41.8, 113.5, 124.3 &1C, q,
Jˆ271 Hz), 124.6 &2C, q, Jˆ4 Hz), 125.3, 125.7, 125.8,
125.9, 127.10, 127.11 &1C, q, Jˆ31 Hz), 127.8 &3C),
128.1, 131.2, 132.3, 133.0, 134.7, 143.7, 164.8, 168.4.
Anal. calcd &found) for C23H19F3N2O2: C, 66.98 &66.87);
H, 4.64 &4.50); N, 6.79% &6.64%).
14.7 Hz), 7.45 &1H, dd, Jˆ7.0, 7.9 Hz), 7.49 &1H, d,
Jˆ8.9 Hz), 7.56 &1H, dd, Jˆ7.0, 7.9 Hz), 7.91 &1H, d,
Jˆ7.9 Hz), 7.93 &1H, d, Jˆ8.9 Hz), 8.01 &1H, d, Jˆ
7.9 Hz), 8.34 &1H, d, Jˆ7.9 Hz). 13C NMR &125.7 MHz,
DMSO-d6): d 22.6, 26.8, 30.3, 48.0, 116.1, 117.6, 123.0,
124.5, 127.0, 128.0, 128.3, 129.6, 130.5, 137.1, 168.2,
169.3. Anal. calcd &found) for C16H16N2O2: C, 71.62
&71.52); H, 6.01 &5.86); N, 10.44% &10.41%).
4.4.10. ꢀE)-1j. Mp137.0±138.0 8C. IR &KBr): 3280, 1660,
1624 cm21. 1H NMR &500 MHz, DMSO-d6): d 0.95 &9H, s),
2.04 &3H, s), 6.98 &1H, s), 7.42 &1H, dd, Jˆ7.9, 7.9 Hz), 7.45
&1H, s), 7.46 &1H, d, Jˆ7.9 Hz), 7.52 &1H, dd, Jˆ6.7,
7.0 Hz), 7.54 &1H, dd, Jˆ7.0, 7.0 Hz), 7.81 &1H, d,
Jˆ7.9 Hz), 7.91 &1H, d, Jˆ6.7 Hz), 7.99 &1H, d,
Jˆ7.0 Hz), 9.62 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 23.6, 27.8 &3C), 50.2, 112.2, 124.7, 125.3, 125.8,
125.9, 126.0, 127.1, 128.2, 131.3, 132.7, 133.1, 135.8,
163.6, 168.6. Anal. calcd &found) for C19H22N2O2: C,
73.52 &73.54); H, 7.14 &7.10); N, 9.03% &9.04%).
4.4.15. 2-Acetylamino-4-ethyl-1,2-dihydro-3ꢀ1H)-benzo-
[f]quinolinone ꢀ2c). Mp221.0±222.0 8C. IR &KBr): 3296,
1
1666, 1634 cm21. H NMR &500 MHz, DMSO-d6): d 1.18
&3H, t, Jˆ7.0 Hz), 1.95 &3H, s), 2.97 &1H, dd, Jˆ14.7,
15.6 Hz), 3.64 &1H, dd, Jˆ6.1, 15.6 Hz), 4.05 &2H, q,
Jˆ7.0 Hz), 4.57 &1H, ddd, Jˆ6.1, 7.6, 14.7 Hz), 7.45 &1H,
dd, Jˆ7.0, 7.3 Hz), 7.51 &1H, d, Jˆ8.9 Hz), 7.56 &1H, dd,
Jˆ7.3, 7.9 Hz), 7.91 &1H, d, Jˆ7.0 Hz), 7.93 &1H, d,
Jˆ8.9 Hz), 8.00 &1H, d, Jˆ7.9 Hz), 8.34 &1H, d,
Jˆ7.6 Hz). 13C NMR &125.7 MHz, DMSO-d6): d 13.1,
22.6, 27.0, 37.6, 48.0, 116.0, 118.1, 123.0, 124.6, 127.0,
128.2, 128.3, 129.6, 130.8, 136.0, 167.9, 169.3. Anal.
calcd &found) for C17H18N2O2: C, 72.32 &71.94); H, 6.43
&6.22); N, 9.92% &9.73%).
4.4.11. ꢀE)-1k. Mp200.0±201.0 8C. IR &KBr): 3272, 1656,
1640 cm21. 1H NMR &500 MHz, DMSO-d6): d 2.05 &3H, s),
6.99 &1H, dd, Jˆ7.3, 7.3 Hz), 7.21 &2H, dd, Jˆ7.3, 7.3 Hz),
7.34 &1H, dd, Jˆ7.0, 8.2 Hz), 7.39 &2H, d, Jˆ7.3 Hz), 7.40
&1H, s), 7.47 &1H, d, Jˆ7.0 Hz), 7.53 &1H, dd, Jˆ7.9,
8.2 Hz), 7.58 &1H, dd, Jˆ7.9, 8.9 Hz), 7.75 &1H, d,
Jˆ8.2 Hz), 7.90 &1H, d, Jˆ8.2 Hz), 8.07 &1H, d,
Jˆ8.9 Hz), 10.00 &1H, s), 10.01 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 23.3, 113.2, 119.8 &2C), 123.4,
124.5, 125.35, 125.39, 125.9, 126.0, 127.3, 128.3, 128.4
&2C), 131.2, 132.1, 133.1, 134.9, 138.8, 163.2, 168.4.
Anal. calcd &found) for C21H18N2O2: C, 76.34 &76.08); H,
5.49 &5.62); N, 8.48% &8.24%).
4.4.16. 2-Acetylamino-1,2-dihydro-4-propyl-3ꢀ1H)-benzo-
[f]quinolinone ꢀ2d). Mp192.5±193.5 8C. IR &KBr): 3304,
1
1668, 1640 cm21. H NMR &500 MHz, DMSO-d6): d 0.88
&3H, t, Jˆ7.3 Hz), 1.51±1.64 &2H, m), 1.95 &3H, s), 2.97
&1H, dd, Jˆ15.0, 15.6 Hz), 3.65 &1H, dd, Jˆ6.1, 15.6 Hz),
3.93±4.09 &2H, m), 4.57 &1H, ddd, Jˆ6.1, 7.9, 15.0 Hz),
7.45 &1H, dd, Jˆ7.3, 7.9 Hz), 7.51 &1H, d, Jˆ8.9 Hz),
7.56 &1H, dd, Jˆ7.3, 7.9 Hz), 7.91 &1H, d, Jˆ7.9 Hz),
7.91 &1H, d, Jˆ8.9 Hz), 8.00 &1H, d, Jˆ7.9 Hz), 8.36 &1H,
d, Jˆ7.9 Hz). 13C NMR &125.7 MHz, DMSO-d6): d 11.0,
20.5, 22.7, 27.0, 43.5, 48.1, 116.3, 118.2, 123.1, 124.6,
127.1, 128.1, 128.3, 129.6, 130.8, 136.0, 168.3, 169.4.
Anal. calcd &found) for C18H20N2O2: C, 72.95 &72.65); H,
6.80 &6.75); N, 9.45% &9.43%).
4.4.12. 2-Acetylamino-1,2-dihydro-3ꢀ1H)-benzo[f]quino-
linone ꢀ2a). Mp305.0±306.0 8C. IR &KBr): 3316, 3204,
1
1690, 1628 cm21. H NMR &500 MHz, DMSO-d6): d 1.95
&3H, s), 2.99 &1H, dd, Jˆ14.6, 15.8 Hz), 3.64 &1H, dd,
Jˆ6.7, 15.8 Hz), 4.61 &1H, ddd, Jˆ6.7, 7.9, 14.6 Hz), 7.16
&1H, d, Jˆ8.6 Hz), 7.39 &1H, dd, Jˆ7.0, 7.9 Hz), 7.52 &1H,
dd, Jˆ7.0, 8.6 Hz), 7.79 &1H, d, Jˆ8.6 Hz), 7.85 &1H, d,
Jˆ7.9 Hz), 7.93 &1H, d, Jˆ8.6 Hz), 8.32 &1H, d,
Jˆ7.9 Hz), 10.45 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 22.7, 27.5, 47.6, 114.6, 116.7, 122.7, 124.0, 127.0,
128.1, 128.5, 129.6, 131.1, 135.0, 168.7, 169.5. Anal. calcd
&found) for C15H14N2O2: C, 70.85 &70.55); H, 5.55 &5.53); N,
11.02% &10.69%).
4.4.17. 2-Acetylamino-1,2-dihydro-4-isopropyl-3ꢀ1H)-
benzo[f]quinolinone ꢀ2e). Mp163.5±164.0 8C. IR &KBr):
1
3356, 1668 cm21. H NMR &500 MHz, DMSO-d6): d 1.47
&3H, d, Jˆ6.7 Hz), 1.52 &3H, d, Jˆ7.3 Hz), 1.93 &3H, s),
2.92 &1H, dd, Jˆ14.7, 15.3 Hz), 3.55 &1H, dd, Jˆ5.5,
15.3 Hz), 4.37 &1H, ddd, Jˆ5.5, 7.9, 14.7 Hz), 4.62 &1H,
qq, Jˆ6.7, 7.3 Hz), 7.44 &1H, dd, Jˆ7.3, 7.9 Hz), 7.52
&1H, d, Jˆ8.6 Hz), 7.54 &1H, dd, Jˆ7.3, 7.9 Hz), 7.88
&1H, d, Jˆ8.6 Hz), 7.89 &1H, d, Jˆ7.9 Hz), 7.99 &1H, d,
Jˆ7.9 Hz), 8.28 &1H, d, Jˆ7.9 Hz). 13C NMR
&125.7 MHz, DMSO-d6): d 19.5, 20.9, 22.6, 27.0, 49.0,
49.6, 117.5, 120.1, 123.2, 124.7, 127.0, 127.7, 128.2,
129.7, 130.6, 137.0, 168.7, 169.4. Anal. calcd &found) for
C18H20N2O2: C, 72.95 &72.61); H, 6.80 &6.71); N, 9.45%
&9.33%).
4.4.13. 2-Acetylamino-2-deutero-1-hydro-3ꢀ1H)-benzo[f]-
quinolinone ꢀdeuteriated 2a). Mp305.0±306.0 8C. 1H
NMR &500 MHz, DMSO-d6): d 1.94 &3H, s), 2.99 &1H, d,
Jˆ15.9 Hz), 3.64 &1H, d, Jˆ15.9 Hz), 7.16 &1H, d,
Jˆ8.6 Hz), 7.39 &1H, dd, Jˆ7.3, 7.9 Hz), 7.52 &1H, dd,
Jˆ7.3, 8.6 Hz), 7.79 &1H, d, Jˆ8.6 Hz), 7.85 &1H, d,
Jˆ7.9 Hz), 7.93 &1H, d, Jˆ8.6 Hz), 8.30 &1H, s), 10.45
&1H, s).
4.4.18. 2-Acetylamino-4-butyl-1,2-dihydro-3ꢀ1H)-benzo-
[f]quinolinone ꢀ2f). Mp157.0±158.0 8C. IR &KBr): 3308,
1
1668, 1642 cm21. H NMR &500 MHz, DMSO-d6): d 0.89
4.4.14. 2-Acetylamino-1,2-dihydro-4-methyl-3ꢀ1H)-benzo-
[f]quinolinone ꢀ2b). Mp231.5±232.5 8C. IR &KBr): 3320,
&3H, t, Jˆ7.3 Hz), 1.31 &2H, tq, Jˆ7.3, 7.6 Hz), 1.50±1.57
&2H, m), 1.95 &3H, s), 2.96 &1H, dd, Jˆ14.6, 15.3 Hz), 3.64
&1H, dd, Jˆ6.1, 15.3 Hz), 3.95±4.14 &2H, m), 4.56 &1H, ddd,
Jˆ6.1, 7.9, 14.6 Hz), 7.45 &1H, dd, Jˆ7.6, 7.9 Hz), 7.51
&1H, d, Jˆ8.2 Hz), 7.55 &1H, dd, Jˆ7.6, 8.2 Hz), 7.91
1
1672, 1634 cm21. H NMR &500 MHz, DMSO-d6): d 1.95
&3H, s), 3.01 &1H, dd, Jˆ14.7, 15.7 Hz), 3.41 &3H, s), 3.65
&1H, dd, Jˆ6.1, 15.7 Hz), 4.57 &1H, ddd, Jˆ6.1, 7.9,

5524
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
&1H, d, Jˆ8.5 Hz), 7.92 &1H, d, Jˆ8.5 Hz), 8.00 &1H, d,
Jˆ8.2 Hz), 8.34 &1H, d, Jˆ7.9 Hz). 13C NMR
&125.7 MHz, DMSO-d6): d 13.7, 19.4, 22.6, 27.0, 29.4,
41.7, 48.1, 116.2, 118.2, 123.1, 124.6, 127.1, 128.1, 128.3,
129.6, 130.8, 136.0, 168.2, 169.4. EI-MS: m/z &%) 310 &M1,
0.57). Anal. calcd &found) for C19H22N2O2: C, 73.52 &73.14);
H, 7.14 &7.13); N, 9.03% &9.11%).
m), 8.17 &1H, d, Jˆ9.2 Hz), 8.27 &1H, br s), 8.92±8.94 &1H,
m), 9.16 &1H, s). 13C NMR &125.7 MHz, DMSO-d6): d 22.6,
113.3, 122.8, 123.8, 126.3, 128.0, 128.7, 128.8, 129.1,
129.7, 132.9, 134.6, 144.6, 157.1, 166.5. Anal. calcd
&found) for C15H12N2O: C, 76.25 &75.96); H, 5.12 &5.02);
N, 11.86% &11.79%).
4.4.23. 2-ꢀMethylaminocarbonyl)-4-methylbenzo[f]iso-
quinoline ꢀ3b). Mp135.0±136.0 8C. IR &KBr): 3406,
4.4.19. 2-Acetylamino-4-benzyl-1,2-dihydro-3ꢀ1H)-benzo-
[f]quinolinone ꢀ2g). Mp256.0±257.0 8C. IR &KBr): 3310,
1
1659 cm21. H NMR &500 MHz, DMSO-d6): d 2.94 &3H,
1
1674, 1641 cm21. H NMR &500 MHz, DMSO-d6): d 1.97
d, Jˆ4.9 Hz), 3.03 &3H, s), 7.81±7.85 &2H, m), 8.11 &1H,
d, Jˆ9.2 Hz), 8.12±8.14 &1H, m), 8.16 &1H, d, Jˆ9.2 Hz),
8.84 &1H, q, Jˆ4.9 Hz), 8.91±8.93 &1H, m), 9.11 &1H, s). 13C
NMR &125.7 MHz, DMSO-d6): d 22.5, 26.0, 112.8, 122.7,
123.8, 126.1, 127.9, 128.6, 128.7, 129.0, 129.5, 132.8,
134.5, 144.3, 157.0, 164.7. Anal. calcd &found) for
C16H14N2O: C, 76.78 &76.69); H, 5.64 &5.71); N, 11.19%
&11.37%).
&3H, s), 3.10 &1H, dd, Jˆ14.7, 15.7 Hz), 3.73 &1H, dd,
Jˆ6.4, 15.7 Hz), 4.78 &1H, ddd, Jˆ6.4, 7.9, 14.7 Hz), 5.31
&2H, s), 7.21 &1H, dd, Jˆ7.0, 7.0 Hz), 7.26±7.32 &4H, m),
7.35 &1H, d, Jˆ8.9 Hz), 7.43 &1H, dd, Jˆ7.6, 8.2 Hz), 7.55
&1H, dd, Jˆ7.6, 8.2 Hz), 7.78 &1H, d, Jˆ8.9 Hz), 7.84 &1H,
d, Jˆ8.2 Hz), 8.02 &1H, d, Jˆ8.2 Hz), 8.45 &1H, d,
Jˆ7.9 Hz). 13C NMR &125.7 MHz, DMSO-d6): d 22.6,
27.0, 45.4, 48.0, 116.4, 118.1, 123.1, 124.6, 126.4 &2C),
126.9, 127.0, 127.9, 128.2, 128.5 &2C), 129.6, 130.6,
136.1, 137.1, 168.7, 169.3. Anal. calcd &found) for
C22H20N2O2: C, 76.72 &77.02); H, 5.85 &5.79); N, 8.13%
&8.09%).
4.4.24. 2-ꢀEthylaminocarbonyl)-4-methylbenzo[f]isoqui-
noline ꢀ3c). Mp104.0±105.0 8C. IR &KBr): 3394,
1
1659 cm21. H NMR &500 MHz, DMSO-d6): d 1.21 &3H,
t, Jˆ7.0 Hz), 3.04 &3H, s), 3.44 &2H, dq, Jˆ6.8, 7.0 Hz),
7.82±7.84 &2H, m), 8.12 &1H, d, Jˆ9.2 Hz), 8.12±8.14
&1H, m), 8.18 &1H, d, Jˆ9.2 Hz), 8.88 &1H, t, Jˆ6.8 Hz),
8.91±8.93 &1H, m), 9.13 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 15.0, 22.5, 33.8, 113.0, 122.8, 123.8, 126.2,
127.9, 128.65, 128.71, 129.1, 129.5, 132.9, 134.6, 144.4,
157.0, 163.8. Anal. calcd &found) for C17H16N2O: C, 77.25
&76.98); H, 6.10 &6.04); N, 10.60% &10.49%).
4.4.20. 2-Acetylamino-1,2-dihydro-4-ꢀ4-methoxybenzyl)-
3ꢀ1H)-benzo[f]quinolinone ꢀ2h). Mp238.0±239.0 8C. IR
&KBr): 3296, 1668, 1638 cm21 1H NMR &500 MHz,
.
DMSO-d6): d 1.98 &3H, s), 3.06 &1H, dd, Jˆ14.7,
15.9 Hz), 3.68 &3H, s), 3.71 &1H, dd, Jˆ6.7, 15.9 Hz),
4.74 &1H, ddd, Jˆ6.7, 7.9, 14.7 Hz), 5.21 &1H, d, Jˆ
15.9 Hz), 5.27 &1H, d, Jˆ15.9 Hz), 6.85 &2H, d, Jˆ
8.6 Hz), 7.20 &2H, d, Jˆ8.6 Hz), 7.39 &1H, d, Jˆ8.6 Hz),
7.43 &1H, dd, Jˆ7.3, 7.9 Hz), 7.55 &1H, dd, Jˆ7.3, 7.9 Hz),
7.79 &1H, d, Jˆ8.6 Hz), 7.84 &1H, d, Jˆ7.9 Hz), 8.01 &1H, d,
Jˆ7.9 Hz), 8.44 &1H, d, Jˆ7.9 Hz). 13C NMR &125.7 MHz,
DMSO-d6): d 22.7, 27.0, 44.8, 48.1, 54.0, 114.0 &2C), 116.6,
118.3, 123.1, 124.7, 127.1, 127.9 &3C), 128.3, 129.0, 129.6,
130.7, 136.1, 158.3, 168.7, 169.4. Anal. calcd &found) for
C23H22N2O3: C, 73.78 &73.52); H, 5.92 &5.84); N, 7.48%
&7.42%).
4.4.25. 4-Methyl-2-ꢀpropylaminocarbonyl)benzo[f]iso-
quinoline ꢀ3d). Mp97.0±98.0 8C. IR &KBr): 3394,
1
1680 cm21. H NMR &500 MHz, DMSO-d6): d 0.94 &3H,
t, Jˆ7.3 Hz), 1.63 &2H, tq, Jˆ7.3, 7.3 Hz), 3.04 &3H, s),
3.38 &2H, dt, Jˆ6.1, 7.3 Hz), 7.82±7.85 &2H, m), 8.11
&1H, d, Jˆ8.5 Hz), 8.10±8.13 &1H, m), 8.16 &1H, d,
Jˆ8.5 Hz), 8.86 &1H, t, Jˆ6.1 Hz), 8.90±8.91 &1H, m),
9.12 &1H, s). 13C NMR &125.7 MHz, DMSO-d6): d 11.4,
22.59, 22.64, 40.7, 113.0, 122.8, 123.8, 126.3, 127.9,
128.67, 128.73, 129.1, 129.6, 132.9, 134.6, 144.4, 157.1,
164.2. Anal. calcd &found) for C18H18N2O: C, 77.67
&77.66); H, 6.52 &6.47); N, 10.06% &10.34%).
4.4.21. 2-Acetylamino-1,2-dihydro-4-[4-ꢀtri¯uoromethyl)-
benzyl]-3ꢀ1H)-benzo[f]quinolinone ꢀ2i). Mp233.0±
234.08C. IR &KBr): 3334, 1680, 1644 cm21 1H NMR
.
&500 MHz, DMSO-d6): d 1.98 &3H, s), 3.14 &1H, dd,
Jˆ14.6, 15.3 Hz), 3.75 &1H, dd, Jˆ6.7, 15.3 Hz), 4.81
&1H, ddd, Jˆ6.7, 7.9, 14.6 Hz), 5.37 &1H, d, Jˆ17.1 Hz),
5.43 &1H, d, Jˆ17.1 Hz), 7.32 &1H, d, Jˆ9.2 Hz), 7.44 &1H,
dd, Jˆ7.3, 7.9 Hz), 7.50 &2H, d, Jˆ7.9 Hz), 7.57 &1H, dd,
Jˆ7.3, 7.9 Hz), 7.68 &2H, d, Jˆ7.9 Hz), 7.80 &1H, d,
Jˆ9.2 Hz), 7.85 &1H, d, Jˆ7.9 Hz), 8.04 &1H, d,
Jˆ7.9 Hz), 8.45 &1H, d, Jˆ7.9 Hz). 13C NMR
&125.7 MHz, DMSO-d6): d 22.6, 26.9, 45.2, 47.9, 116.1,
118.2, 123.1, 124.1 &1C, q, Jˆ273 Hz), 124.7, 125.4 &2C,
q, Jˆ4 Hz), 127.1, 127.2 &2C), 127.6 &1C, q, Jˆ31 Hz),
128.0, 128.2, 129.6, 130.6, 135.8, 142.1, 168.8, 169.3.
Anal. calcd &found) for C23H19F3N2O2: C, 66.98 &66.87);
H, 4.64 &4.65); N, 6.79% &6.60%).
4.4.26. 2-ꢀIsopropylaminocarbonyl)-4-methylbenzo[f]iso-
quinoline ꢀ3e). Mp160.5±161.0 8C. IR &KBr): 3370,
1
1668 cm21. H NMR &500 MHz, DMSO-d6): d 1.27 &6H,
d, Jˆ6.1 Hz), 3.04 &3H, s), 4.23 &1H, dq, Jˆ6.1, 8.6 Hz),
7.81±7.85 &2H, m), 8.12 &1H, d, Jˆ9.2 Hz), 8.11±8.14 &1H,
m), 8.17 &1H, d, Jˆ9.2 Hz), 8.52 &1H, d, Jˆ8.6 Hz), 8.90±
8.93 &1H, m), 9.13 &1H, s). 13C NMR &125.7 MHz, DMSO-
d6): d 22.4 &2C), 22.5, 40.8, 113.0, 122.8, 123.8, 126.3,
127.9, 128.6, 128.7, 129.1, 129.6, 132.9, 134.6, 144.3,
157.1, 163.2. Anal. calcd &found) for C18H18N2O: C, 77.67
&77.79); H, 6.52 &6.58); N, 10.06% &10.10%).
4.4.27. 2-ꢀButylaminocarbonyl)-4-methylbenzo[f]isoqui-
noline ꢀ3f). Mp61.5±62.5 8C. IR &KBr): 3382, 1668 cm21
.
1H NMR &500 MHz, DMSO-d6): d 0.94 &3H, t, Jˆ7.3 Hz),
1.37 &2H, tq, Jˆ7.3, 7.6 Hz), 1.60 &2H, tt, Jˆ7.0, 7.6 Hz),
3.04 &3H, s), 3.41 &2H, dt, Jˆ6.1, 7.0 Hz), 7.81±7.85 &2H,
m), 8.12 &1H, d, Jˆ9.2 Hz), 8.11±8.15 &1H, m), 8.17 &1H, d,
Jˆ9.2 Hz), 8.83 &1H, t, Jˆ6.1 Hz), 8.90±8.93 &1H, m), 9.12
4.4.22. 2-Aminocarbonyl-4-methylbenzo[f]isoquinoline
1
ꢀ3a). Mp254.0±255.5 8C. IR &KBr): 3442, 1683 cm21. H
NMR &500 MHz, DMSO-d6): d 3.03 &3H, s), 7.76 &1H, br s),
7.83±7.84 &2H, m), 8.12 &1H, d, Jˆ9.2 Hz), 8.12±8.14 &1H,

K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
5525
&1H, s). 13C NMR &125.7 MHz, DMSO-d6): d 13.7, 19.6,
22.6, 31.5, 38.6, 113.0, 122.8, 123.8, 126.2, 127.9, 128.65,
128.71, 129.1, 129.5, 132.9, 134.6, 144.4, 157.0, 164.1. EI-
MS: m/z &%) 292 &M1, 8.94). Anal. calcd &found) for
C19H20N2O: C, 78.05 &77.85); H, 6.89 &7.09); N, 9.58%
&9.74%).
Jˆ7.6, 7.6 Hz), 7.41 &2H, dd, Jˆ7.6, 7.9 Hz), 7.82±7.86
&2H, m), 7.95 &2H, d, Jˆ7.9 Hz), 8.13±8.14 &1H, m), 8.16
&1H, d, Jˆ9.2 Hz), 8.21 &1H, d, Jˆ9.2 Hz), 8.97±8.99 &1H,
m), 9.25 &1H, s), 10.65 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 22.5, 113.7, 120.1 &2C), 122.8, 123.9,
124.0, 126.6, 128.0, 128.6, 128.7 &3C), 129.2, 130.0,
132.9, 134.7, 138.3, 143.9, 157.3, 162.7. Anal. calcd
&found) for C21H16N2O: C, 80.75 &80.87); H, 5.16 &5.09);
N, 8.97% &9.07%).
4.4.28. 2-ꢀBenzylaminocarbonyl)-4-methylbenzo[f]iso-
quinoline ꢀ3g). Mp147.0±148.0 8C. IR &KBr): 3394,
1
1674 cm21. H NMR &500 MHz, DMSO-d6): d 3.04 &3H,
s), 4.62 &2H, d, Jˆ6.4 Hz), 7.26 &1H, dd, Jˆ7.3, 7.3 Hz),
7.34 &2H, dd, Jˆ7.3, 7.6 Hz), 7.40 &2H, d, Jˆ7.6 Hz), 7.81±
7.85 &2H, m), 8.13±8.14 &1H, m), 8.14 &1H, d, Jˆ8.9 Hz),
8.19 &1H, d, Jˆ8.9 Hz), 8.93±8.95 &1H, m), 9.17 &1H, s),
9.39 &1H, t, Jˆ6.4 Hz). 13C NMR &125.7 MHz, DMSO-d6):
d 22.5, 42.4, 113.2, 122.7, 123.8, 126.3, 126.7, 127.4 &2C),
127.9, 128.2 &2C), 128.6, 128.7, 129.0, 129.6, 132.8, 134.5,
139.6, 144.2, 157.1, 164.2. Anal. calcd &found) for
C22H18N2O: C, 80.96 &81.05); H, 5.56 &5.47); N, 8.58%
&8.70%).
We succeeded in isolating small amounts of cis-4j, trans-4j,
1
cis-4k and trans-4k whose H and 13C NMR spectra were
consistent with the proposed structures, although the cis-
and trans-isomers isolated, in most cases, were contami-
nated with the azetine-derived decomposition products.
4.4.33. cis-4-ꢀtert-Butylaminocarbonyl)-2-methyl-3-ꢀ1-
naphthyl)-1-azetine ꢀcis-4j). White solid. IR &KBr): 3280,
1
1680, 1650 cm21. H NMR &500 MHz, DMSO-d6): d 0.48
&9H, s), 2.15 &3H, d, Jˆ1.2 Hz), 5.11 &1H, dd, Jˆ1.2,
10.4 Hz), 6.46 &1H, d, Jˆ10.4 Hz), 6.75 &1H, s), 7.42±
7.45 &2H, m), 7.51 &1H, dd, Jˆ6.1, 6.7 Hz), 7.53 &1H, dd,
Jˆ6.1, 6.7 Hz), 7.79±7.81 &1H, m), 7.89 &1H, d, Jˆ6.7 Hz),
8.00 &1H, d, Jˆ6.7 Hz). 13C NMR &125.7 MHz, DMSO-d6):
d 13.7, 27.3 &3C), 49.2, 72.9, 80.0, 123.5, 124.1, 124.9,
125.4, 125.6, 127.6, 128.1, 130.1, 132.8, 132.9, 165.6,
166.4.
4.4.29. 2-ꢀ4-Methoxybenzylaminocarbonyl)-4-methyl-
benzo[f]isoquinoline ꢀ3h). Mp142.0±143.0 8C. IR &KBr):
1
3382, 1671 cm21. H NMR &500 MHz, DMSO-d6): d 3.03
&3H, s), 3.73 &3H, s), 4.54 &2H, d, Jˆ6.1 Hz), 6.91 &2H, d,
Jˆ8.5 Hz), 7.34 &2H, d, Jˆ8.5 Hz), 7.82±7.85 &2H, m), 8.13
&1H, d, Jˆ9.2 Hz), 8.12±8.15 &1H, m), 8.17 &1H, d,
Jˆ9.2 Hz), 8.91±8.93 &1H, m), 9.16 &1H, s), 9.30 &1H, t,
Jˆ6.1 Hz). 13C NMR &125.7 MHz, DMSO-d6): d 22.6, 42.0,
55.1, 113.3, 113.7 &2C), 123.8, 126.4, 127.8, 128.7, 128.8,
128.9 &3C), 129.2, 129.7, 131.6, 132.9, 134.6, 144.3, 157.2,
158.3, 164.2. Anal. calcd &found) for C23H20N2O2: C, 77.51
&77.11); H, 5.66 &5.67); N, 7.86% &7.75%).
4.4.34. trans-4-ꢀtert-Butylaminocarbonyl)-2-methyl-3-ꢀ1-
naphthyl)-1-azetine ꢀtrans-4j). Oily liquid. 1H NMR
&500 MHz, DMSO-d6): d 1.30 &9H, s), 2.14 &3H, d,
Jˆ1.2 Hz), 4.31 &1H, dd, Jˆ1.2, 7.0 Hz), 6.28 &1H, d,
Jˆ7.0 Hz), 7.49±7.59 &4H, m), 7.73 &1H, s), 7.78 &1H, d,
Jˆ7.9 Hz), 7.92 &1H, d, Jˆ7.9 Hz), 8.00 &1H, d, Jˆ7.6 Hz).
13C NMR &125.7 MHz, DMSO-d6): d 13.5, 28.3 &3C), 50.4,
77.1, 80.2, 122.0, 122.8, 125.5, 126.0, 126.4, 128.2, 128.8,
129.2, 133.4, 135.9, 164.6, 169.3.
4.4.30. 4-Methyl-2-[4-ꢀtri¯uoromethyl)benzylaminocar-
bonyl]benzo[f]isoquinoline ꢀ3i). Mp149.0±149.5 8C. IR
1
&KBr): 3376, 1671 cm21. H NMR &500 MHz, DMSO-d6):
d 3.05 &3H, s), 4.70 &2H, d, Jˆ6.1 Hz), 7.61 &2H, d,
Jˆ8.6 Hz), 7.71 &2H, d, Jˆ8.6 Hz), 7.81±7.85 &2H, m),
8.13 &1H, d, Jˆ9.2 Hz), 8.12±8.14 &1H, m), 8.18 &1H, d,
Jˆ9.2 Hz), 8.91±8.93 &1H, m), 9.16 &1H, s), 9.57 &1H, t,
Jˆ6.1 Hz). 13C NMR &125.7 MHz, DMSO-d6): d 22.5, 42.2,
113.3, 122.7, 123.8, 125.3 &1C, q, Jˆ271 Hz), 125.1 &2C, q,
Jˆ4 Hz), 126.4, 127.4 &1C, q, Jˆ33 Hz), 127.9, 128.0 &2C),
128.6, 128.7, 129.1, 129.7, 132.8, 134.5, 144.0, 144.6,
157.2, 164.6. Anal. calcd &found) for C23H17F3N2O: C,
70.04 &69.81); H, 4.34 &4.31); N, 7.10% &7.03%).
4.4.35. cis-4-Anilinocarbonyl-2-methyl-3-ꢀ1-naphthyl)-1-
azetine ꢀcis-4k). Mp172.0±173.0 8C. IR &KBr): 3350, 1695,
1660 cm21. 1H NMR &500 MHz, DMSO-d6): d 2.22 &3H, s),
5.30 &1H, d, Jˆ10.4 Hz), 6.63 &1H, d, Jˆ10.4 Hz), 6.82 &2H,
d, Jˆ7.9 Hz), 6.87 &1H, dd, Jˆ7.3, 7.3 Hz), 7.03 &2H, dd,
Jˆ7.3, 7.9 Hz), 7.42 &1H, dd, Jˆ7.9, 7.9 Hz), 7.45 &1H, dd,
Jˆ7.3, 7.9 Hz), 7.52 &1H, dd, Jˆ7.9, 8.5 Hz), 7.53 &1H, d,
Jˆ7.9 Hz), 7.77 &1H, d, Jˆ7.9 Hz), 7.83 &1H, d, Jˆ7.9 Hz),
8.06 &1H, d, Jˆ8.5 Hz), 9.32 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 13.9, 73.6, 80.0, 120.1 &2C), 123.4, 123.5,
123.7, 124.9, 125.5, 125.9, 127.9, 128.1 &2C), 128.2,
129.9, 132.6, 132.7, 137.6, 166.5, 166.8. Anal. calcd
&found) for C21H18N2O´H2O: C, 75.88 &76.20); H, 6.06
&5.83); N, 8.43% &8.26%).
4.4.31. 2-ꢀtert-Butylaminocarbonyl)-4-methylbenzo[f]iso-
quinoline ꢀ3j). Mp211.5±212.5 8C. IR &KBr): 3376,
1
1671 cm21. H NMR &500 MHz, DMSO-d6): d 1.49 &9H,
s), 3.03 &3H, s), 7.82±7.86 &2H, m), 8.13 &1H, d,
Jˆ9.2 Hz), 8.12±8.15 &1H, m), 8.19 &1H, d, Jˆ9.2 Hz),
8.30 &1H, s), 8.92±8.94 &1H, m), 9.14 &1H, s). 13C NMR
&125.7 MHz, DMSO-d6): d 22.7, 28.5 &3C), 50.3, 112.6,
122.8, 123.8, 126.3, 128.0, 128.67, 128.74, 129.2, 129.6,
132.9, 134.7, 144.5, 157.0, 163.1. Anal. calcd &found) for
C19H20N2O: C, 78.05 &77.98); H, 6.89 &6.74); N, 9.58%
&9.76%).
4.4.36. trans-4-Anilinocarbonyl-2-methyl-3-ꢀ1-naphthyl)-
1-azetine ꢀtrans-4k). Oily liquid. 1H NMR &500 MHz,
DMSO-d6): d 2.20 &3H, d, Jˆ1.2 Hz), 4.61 &1H, dd, Jˆ1.2,
7.0 Hz), 6.49 &1H, d, Jˆ7.0 Hz), 7.11 &1H, dd, Jˆ7.6,
7.6 Hz), 7.35 &2H, dd, Jˆ7.6, 7.9 Hz), 7.52±7.58 &4H, m),
7.66 &2H, d, Jˆ7.9 Hz), 7.85±7.87 &1H, m), 7.95±7.97 &1H,
m), 8.01±8.03 &1H, m), 10.20 &1H, s). 13C NMR &125.7 MHz,
DMSO-d6): d 13.5, 77.2, 80.0, 119.6 &2C), 122.5, 122.6,
123.8, 125.5, 126.1, 126.7, 128.6, 128.8 &2C), 129.0, 129.2,
133.5, 135.4, 138.5, 165.5, 168.6.
4.4.32. 2-Anilinocarbonyl-4-methylbenzo[f]isoquinoline
1
ꢀ3k). Mp212.0±213.0 8C. IR &KBr): 3256, 1674 cm21. H
NMR &500 MHz, DMSO-d6): d 3.10 &3H, s), 7.15 &1H, dd,

5526
K. Maekawa et al. / Tetrahedron 57 02001) 5515±5526
6. Lewis, F. D.; Reddy, G. D. J. Am. Chem. Soc. 1989, 111,
4.5. Control experiments
6465±6466. Lewis, F. D.; Reddy, G. D.; Bassani, D. M.
J. Am. Chem. Soc. 1993, 115, 6468±6469. Lewis, F. D.;
Bassani, D. M.; Reddy, G. D. J. Org. Chem. 1993, 58,
6390±6393. Lewis, F. D.; Reddy, G. D.; Bassani, D. M.;
Schneider, S.; Gahr, M. J. Am. Chem. Soc. 1994, 116, 597±
605. Lewis, F. D.; Bassani, D. M.; Burch, E. L.; Cohen, B. E.;
Engleman, J. A.; Reddy, G. D.; Schneider, S.; Jaeger, W.;
Gedeck, P.; Gahr, M. J. Am. Chem. Soc. 1995, 117, 660±669.
7. &a) Kubo, K.; Yaegashi, S.; Sasaki, K.; Sakurai, T.; Inoue, H.
Tetrahedron Lett. 1996, 37, 5917±5920. &b) Kubo, K.;
Koshiba, M.; Hoshina, H.; Sakurai, T. Heterocycles 1998,
48, 25±29. &c) Hoshina, H.; Kubo, K.; Morita, A.; Sakurai,
T. Tetrahedron 2000, 56, 2941±2951. &d) Hoshina, H.; Tsuru,
H.; Kubo, K.; Igarashi, T.; Sakurai, T. Heterocycles 2000, 53,
2261±2274.
A MeOH solution &100 mL) of &Z)-1f &6.6£1023 mol dm23),
placed in a Pyrex vessel, was irradiated for 40 h under nitro-
gen at room temperature with Pyrex-®ltered light from a
450 W high-pressure Hg lamp. After 40 h irradiation, an
aliquot &5 mL) of the solution was pipetted off and concen-
trated to dryness in vacuo. The resulting residue was
1
dissolved in DMSO-d6 and subjected to H NMR analysis.
The remaining solution was concentrated to dryness under
reduced pressure and the resulting residue was subjected to
preparative thin-layer chromatography over silica gel
&EtOAc±hexane). This procedure allowed us to isolate
&Z)-1f, &E)-1f, 3f and 5f &major product). Physical and spec-
troscopic properties of 5f are shown below.
On the other hand, we employed a 1H NMR tube instead of a
Pyrex vessel in order to investigate whether the concentra-
tion of TEA is changed during irradiation. A CD3OD solu-
tion of &Z)-1f &2.5£1022 mol dm23) containing TEA
&0.10 mol dm23) and 1,4-dioxane &0.10 mol dm23) was
placed in a NMR tube and sealed after the solution was
saturated with nitrogen. This sealed solution was irradiated
for 4±8 h at room temperature with Pyrex-®ltered light from
8. Sakurai, T.; Miyoshi, K.; Obitsu, M.; Inoue, H. Ber.
Bunsenges. Phys. Chem. 1996, 100, 46±54. Miyoshi, K.;
Kubo, K.; Sakurai, T.; Inoue, H. Nippon Kagaku Kaishi
1999, 37±44 and references cited therein. Ozawa, K.;
Miyoshi, K.; Kubo, K.; Igarashi, T.; Sakurai, T. Nippon
Kagaku Kaishi 2000, 511±516.
9. Lewis, F. D. Acc. Chem. Res. 1979, 12, 152±158. Kavarnos,
G. J.; Turro, N. J. Chem. Rev. 1986, 86, 401±449.
1
10. Rao, Y. S.; Filler, R. Synthesis 1975, 749±764. Rzeszotarska,
B.; Karolak-Wojciechowska, J.; Broda, M. A.; Galdecki, Z.;
Trzezwinska, B.; Koziol, A. E. Int. J. Peptide Protein Res.
1994, 44, 313±319.
a 450 W high-pressure Hg lamp and subjected to H NMR
analysis.
4.5.1. 2-Acetylamino-4-butyl-3ꢀ1H)-benzo[f]quinolinone
ꢀ5f). Mp163.0±164.0 8C. IR &KBr): 3346, 1620,
11. Kolbe, A.; Kaps, P.; Plass, M. Z. Phys. Chem. 1995, 191, 191±
195.
1
1600 cm21. H NMR &500 MHz, CDCl3): d 1.03 &3H, t,
Jˆ7.3 Hz), 1.53 &2H, tq, Jˆ7.3, 7.6 Hz), 1.82 &2H, tt,
Jˆ7.6, 7.9 Hz), 2.29 &3H, s), 4.50 &2H, t, Jˆ7.9 Hz), 7.54
&1H, dd, Jˆ6.7, 8.2 Hz), 7.54 &1H, d, Jˆ9.2 Hz), 7.66 &1H,
dd, Jˆ6.7, 8.6 Hz), 7.87 &1H, d, Jˆ8.2 Hz), 7.91 &1H, d,
Jˆ9.2 Hz), 8.47 &1H, d, Jˆ8.6 Hz), 8.65 &1H, s), 9.68
&1H, s). 13C NMR &125.7 MHz, CDCl3): d 13.8, 20.3,
25.0, 30.2, 43.7, 114.2, 115.8, 116.1, 122.6, 125.6, 127.7,
127.8, 128.4, 129.5, 129.8, 130.0, 133.1, 157.3, 169.4. EI-
MS: m/z &%) 308 &M1, 14.90). Anal. calcd &found) for
C19H20N2O2: C, 74.00 &73.55); H, 6.54 &6.37); N, 9.08%
&8.90%).
12. Jencks, W. P. In Catalysis in Chemistry and Enzymology;
McGraw-Hill: New York, 1969; pp 323±350. Sakurai, T.;
Wada, K.; Inoue, H. Nippon Kagaku Kaishi 1993, 728±733.
13. &a) Lenz, G. R. Synthesis 1978, 489±518. &b) Naruto, S.;
Yonemitsu, O. Chem. Pharm. Bull. 1980, 28, 900±909.
&c) Hamada, T.; Okuno, Y.; Ohmori, M.; Nishi, T.;
Yonemitsu, O. Chem. Pharm. Bull. 1981, 29, 128±136.
&d) Ninomiya, I.; Hashimoto, C.; Kiguchi, T.; Naito, T.
J. Chem. Soc., Perkin Trans. 1 1985, 941±948. &e) Jones,
K.; Thompson, M.; Wright, C. J. Chem. Soc., Chem. Commun.
1986, 115±116. &f) Mascal, M.; Moody, C. J. J. Chem. Soc.,
Chem. Commun. 1988, 587±588. &g) Johnson, G. P.; Marples,
B. A. J. Chem. Soc., Perkin Trans. 1 1988, 3399±3406.
&h) Beck, A. L.; Mascal, M.; Moody, C. J.; Slawin, A. M. Z.;
Williams, D. J.; Coates, W. J. J. Chem. Soc., Perkin Trans. 1
1992, 797±811. &i) Beck, A. L.; Mascal, M.; Moody, C. J.;
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