Synthesis of the naphthalenone, dihydroquinoline, and dihydrofuran derivatives

Article abstract of DOI:10.1002/hlca.201000386

The reactions of enaminones with dimethyl diazomalonate were investigated in the presence of copper(II) acetylacetonate. From the reaction of (E)-3-[methyl(phenyl)amino]-1-phenylprop-2-en-1-one (6c), dimethyl 2-[methyl(phenyl)amino]-4-oxonaphthalene-1,1-(4H)-dicarboxylate, was unexpectedly obtained as the major product. Quinoline derivatives were formed as the major products in the case of N-methyl-p-anisidino and N-methyl-p-toluidino enaminones. The reactions of acetyl enaminones were also realized, and quinoline derivatives were isolated as the major products. 3H- and 5H-dihydrofurans were also formed as side products in these reactions. These results differ from those reported earlier on the reactions of tertiary enaminones with carbenes/metal carbenes.

Full text of DOI:10.1002/hlca.201000386

Helvetica Chimica Acta – Vol. 94 (2011)
1115
Synthesis of the Naphthalenone, Dihydroquinoline, and Dihydrofuran
Derivatives
by Fꢀsun S¸eyma Gꢀngçr, Olcay AnaÅ*, and ꢁzkan Sezer*
Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469, Maslak,
Istanbul, Turkey (phone: þ 902122853346; fax: þ 902122856386; e-mail: oosezer@itu.edu.tr)
The reactions of enaminones with dimethyl diazomalonate were investigated in the presence of
copper(II) acetylacetonate. From the reaction of (E)-3-[methyl(phenyl)amino]-1-phenylprop-2-en-1-
one (6c), dimethyl 2-[methyl(phenyl)amino]-4-oxonaphthalene-1,1-(4H)-dicarboxylate, was unexpect-
edly obtained as the major product. Quinoline derivatives were formed as the major products in the case
of N-methyl-p-anisidino and N-methyl-p-toluidino enaminones. The reactions of acetyl enaminones were
also realized, and quinoline derivatives were isolated as the major products. 3H- and 5H-dihydrofurans
were also formed as side products in these reactions. These results differ from those reported earlier on
the reactions of tertiary enaminones with carbenes/metal carbenes.
Introduction. – During the past decade, we have studied the formal 1,5-electrocyclic
reaction of carbonyl ylides derived from a,b-unsaturated ketones, esters, diesters, and
enaminones [1 – 7]. The reactions of a,b-unsaturated ketones and esters with diazo
dicarbonyl compounds such as dimethyl diazomalonate (¼dimethyl 2-diazopropane-
dioate) yielded in the presence of copper(II) acetylacetonate (Cu(acac)2) mainly
dihydrofuran derivatives. On the other hand, the reactions of a,b-enals were found to
yield dioxolanes, instead. Furthermore, a-benzylidene-b-dicarbonyl compounds with at
least one ketone group yielded by 1,7-electrocyclizations of intermediate keto carbonyl
ylides dihydrobenzoxepines 5 as the main products along with dihydrofurans 4 in
varying ratios (Scheme 1) [6]. Analogous 1,5-electrocyclizations reported by Hama-
guchi and Matsubara [8], and Sliwinska and Warkentin [9] yielded only dihydrofurans
under different reaction conditions and with different starting compounds.
Enaminones, which are ꢀpush-pullꢁ olefins, are versatile synthetic intermediates.
Kascheres and co-workers have studied the reactions of primary and secondary
enaminones with diazocarbonyl compounds in the presence of copper catalysts [10 –
13]. They obtained HꢀC(a) or HꢀN carbene insertion products, depending on the
structure of the enaminones. On the other hand, the Cu-catalyzed reactions of acyclic
tertiary enaminones with diazoacetates were reported by Maas and Mꢀller to yield
ꢀpush-pullꢁ cyclopropanes and their rearrangement products [14]. In this study,
dihydrofuran derivatives were only detected in a few reactions in trace amounts. Maas
and co-workers have also investigated the reactions of semicyclic enaminones with
vinyl diazoacetate, and they obtained betaines and dienamines [15][16].
AnaÅ and co-workers recently reported their initial findings on the reactions of
tertiary enaminones with dimethyl diazomalonate (E2C¼N2, E ¼ CO2Me) in the
presence of Cu(acac)2 [5], which, in contrast to the literature, revealed the presence of
ꢂ 2011 Verlag Helvetica Chimica Acta AG, Zꢃrich

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Helvetica Chimica Acta – Vol. 94 (2011)
Scheme 1. The Reaction of a,b-Unsaturated Carbonyl Compounds with E2C¼N2
significant amounts of dihydrofuran products, along with naphthalenone derivatives 9
and HꢀC(a) insertion products 11 (Scheme 2). Here, we present further results on the
reactions of several tertiary enaminones and E2C¼N2 with Cu(acac)2 as the catalyst.
Scheme 2. The Reactions of Enaminones and E2C¼N2
Results and Discussion. – We repeated the reaction of (E)-3-[methyl(phenyl)-
amino]-1-phenylprop-2-en-1-one (6c) with dimethyl diazomalonate with different
catalysts in addition to Cu(acac)2. Although we had studied this reaction with
Cu(acac)2 before [5], the unexpected naphthalenone product prompted us to re-
investigate the reaction with copper(II) triflate (Cu(OTf)2), copper(II) hexafluoro-
acetylacetonate (Cu(hfacac)2), dirhodium tetraacetate (Rh2(AcO)4), rhodium(II)
trifluoroacetate dimer (Rh2(CF3CO2)4) as catalysts. The results are shown in Table 1.

Helvetica Chimica Acta – Vol. 94 (2011)
1117
Table 1. Reaction of (2E)-3-[Methyl(phenyl)amino]-1-phenylprop-2-en-1-one (6c) with Dimethyl
Diazomalonatea)
Catalyst
7c
8c
9c
10c
11c
Cu(acac)2 [5]
Cu(OTf)2
Cu(hfacac)2
Rh2(AcO)4
Rh2(CF3CO2)4
1
1
1
1
1
–
–
–
–
–
3.52
0.35
0.09
0.05
–
–
–
–
–
–
–
–
–
–
–
a) Reaction conditions: 2.1 mmol of 6c and catalyst (0.01 mmol) in 10 ml of benzene, and E2C¼N2
(1.4 mmol) in 1 ml of benzene, reflux, under N2; GC analysis, relative product ratios with respect to 7c.
As can be seen from Table 1, naphthalenone 9c was distinctly preferred with
Cu(acac)2 as a catalyst. To obtain different derivatives and to better understand
naphthalenone formation, we continued our experiments with only Cu(acac)2 as
catalyst with further enaminones and E2C¼N2. Along with the new enaminones, we
also repeated the reaction of 6a [5], and this allowed us to isolate new products. The
new results are depicted in Scheme 2 and compiled in Table 2.
a
Table 2. Cu(acac)2-Catalyzed Reactions of Enaminones and E2C¼N2
)
Entry R1
R2
R3
R4
7
8
9
10
11
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Me Me
ꢀ(CH2)5ꢀ
Me Ph
–
–
–
–
–
1b)
1b)
1b)
1b)d)
1
0.33
–
–
–
–
–
–
–
0.56b)
–
–
–
–
–
–
–
–
–
–
0.30
–
–
–
–
0.35c)
0.53d) 3.52b)
–
Ph
Ph
2.47b)
–
–
–
–
–
–
–
–
0.84
–
–
–
Me 4-O2NꢀC6H4
–
Me 4-MeOꢀC6H4 MeO 1e)
1e)
3.52
c
Me 4-MeꢀC6H4
Me
H
H
H
–
–
H
H
1
1
1d)
1
1
–
1
–
)
1.27
11.73
14.30
1.20
–
4-O2NꢀC6H4
4-MeOꢀC6H4
4-MeꢀC6H4
3-O2NꢀC6H4
3-MeOꢀC6H4
Me Ph
–
Me Ph
Me Ph
Me Me
Me Me
0.72
0.98
–
1
1
–
5.08
1
–
Naphthalen-2-yl Me Ph
–
Me
Me
Me
Me Ph
1f)
Me 4-MeOꢀC6H4 MeO 1g)
5.36
1.13
Me 4-MeꢀC6H4
Me
1
a) Normalized by GC values. b) Values taken from [5]. c) Not isolated in pure state. Structure assignment
e
based on 1H-NMR of an impure sample and GC/MS. d) Not isolated in pure state. ) Two products give a
single peak in GC. The ratio 7/8 is unknown. f) No other product was isolated. g) The product was
isolated as a mixture with 8o.
Contrary to the data of Maas and co-workers, our new results also supported that all
these reactions gave 3H-dihydrofuran derivatives 7 (except for Entries l and n). The
reaction of 6e and 6k afforded 3H-dihydrofurans as the only products, representing a
method of the synthesis of these polyfunctional derivatives as valuable building blocks.
When dimethylamino- (i.e., 6a and 6l) and piperidino- (i.e., 6b) substituted starting

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Helvetica Chimica Acta – Vol. 94 (2011)
materials were used, HꢀC(a) insertion products were also observed as by-products.
According to literature, these HꢀC(a) insertion products may be formed by two
general pathways as summarized below.
i) As enaminones are known to have different nucleophilic sites (N, C(a), and O)
[10][13], the electrophilic attack of a carbene at C(a) may be conceived as depicted in
Scheme 3 (pathway i).
Scheme 3. Formation of HꢀC(a) Insertion Products
ii) A metallacyclobutane intermediate, either formed directly (pathway ii-1) or
formed by transition-metal-catalyzed rearrangement of an intermediate donorꢀac-
ceptor substituted cyclopropane (pathway ii-2), can lead to the HꢀC(a) insertion
product 11a [17].
As can be seen from Table 2, the reaction of enaminones 6c, 6d, and 6m, give the
naphthalenone derivatives 9c, 9d, and 9m as major products. These products can be
formed via two pathways:
i) A donorꢀacceptor-substituted cyclopropane intermediate is initially formed,
which then undergoes ring opening and subsequent rearrangement to a benzoyl-
propenedicarboxylate system. Finally, naphthalenone derivative is obtained by 1,6-
electrocyclization, followed by aromatization (Scheme 4). Since this mechanism
involves the same cyclopropane intermediate as the previously discussed HꢀC(a)
insertion mechanisms (Scheme 3, pathway ii-2) and shows similarity with the quinoline-
formation mechanisms, which will be discussed below, it seems to be a more probable
route for the formation of the naphthalenone derivatives.

Helvetica Chimica Acta – Vol. 94 (2011)
1119
Scheme 4. Formation of Naphthalenone Derivatives: Pathway 1
ii) Electrophilic carbene attacks the amine group to form a nitrogen ylide
intermediate, whose C-atom attacks the Ph ring. The intermediate then undergoes
further rearrangements to give compound 9c (Scheme 5).
In the reaction of 6h, 6i, 6j, and 6n, quinoline derivatives 10 were obtained as major
products, the structures of which were determined by their 1H- and 13C-NMR spectra as
well as the crystallographic analysis of 10n (Fig. 1).
The quinoline derivatives are formed probably via the ring opening and subsequent
dehydrogenation, and finally 1,6-ring closure of an initially formed ꢀpush-pullꢁ
cyclopropane derivative (Scheme 6, pathway i). The initial intermediate may be a
betain derivative formed by the attack of a carbenoid at C(a) (Scheme 6, pathway ii).
The last probable route (Scheme 6, pathway iii) may proceed via the initial carbene
attack at the ortho-position of the aniline ring and further necessary transformations.
The absence of a quinoline product with the p-nitroanilino enaminone 6e supports this
last route, which appears reasonable taking into account the high electrophilicity of
E2C. However, our inability to detect any products resulting from a para- instead of
ortho-attack raises questions about the validity of pathway iii.
As we reported before [1][3][4][6], the formation of 3H-dihydrofuran derivatives
7 has to be attributed to a 1,5-electrocyclization of carbonyl ylide intermediates
(Scheme 7, pathway iii). In this study, some of our reactions, however, yielded
additionally novel 5H-dihydrofuran derivatives 8. A comparison of the 1H-NMR
spectra of the dihydrofurans 7f and 8f are displayed in Fig. 2,a. The 3H-dihydrofuran

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Helvetica Chimica Acta – Vol. 94 (2011)
Scheme 5. Formation of Naphthalenone Derivatives: Pathway 2
Fig. 1. X-Ray crystal structure of 10n

Helvetica Chimica Acta – Vol. 94 (2011)
Scheme 6. Formation of Quinoline Derivatives
1121
structure of 7f (d(H) 5.92 (d, J ¼ 2.7), 5.41 (d, J ¼ 2.9); Fig. 2,b) was further verified
by crystallographic analysis (Fig. 3).
Of the two possible structures assignable to the second dihydrofuran isomer,
namely 8 or 12, we established that the actual structure was that of a 5H-dihydrofuran 8
(Scheme 7, pathway ii). The other dihydrofuran derivative 12 may have been formed by
ring opening of a donorꢀacceptor cyclopropane intermediate (Scheme 7, pathway i). In
the 13C-NMR spectra of the new dihydrofuran isomers, a signal between d(C) 118 and
126 ppm was recognizable, which is not attributable to C(4) of the hypothetical 2H-
dihydrofuran 12. All spectral data fit best the 5H-dihydrofuran structure 8. The
chemical shifts and coupling constants of compounds 7 and 8 are listed in Tables 3 and
4, respectively.
The formation of 3H-dihydrofurans 7 has been attributed to 1,5-electrocyclization
of carbonyl ylide intermediates. Now that the 3H-dihydrofurans are observed along
with their 5H-isomers, the epoxide route in Scheme 7, pathway ii, can be alternative
mechanism, whereas the 1,5-electrocyclization might still be valid for the 3H-isomers.
Conclusions. – Cu(acac)2-Catalyzed reactions of tertiary enaminones and dimethyl
diazomalonate (E2C¼N2, E ¼ CO2Me) lead to significant amounts of 3H- and 5H-
dihydrofuran derivatives. Tertiary enaminones with benzoyl, and N-methyl and/or N-

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Helvetica Chimica Acta – Vol. 94 (2011)
Scheme 7. Formation of Dihdyrofuran Derivatives 7 and 8
Fig. 2. 1H-NMR Spectra of dihydrofuran derivatives 7f and mixture 7f/8f

Helvetica Chimica Acta – Vol. 94 (2011)
1123
Fig. 3. X-Ray crystal structure of 7f
Table 3. Chemical Shifts and Coupling Constants for 3H-Dihydrofuran Derivatives 7
7a
7b
7c
7e
7f
7g
7h
7j
7k
7m
7o
7p
d(H) for HꢀC(3) 4.77 4.73 5.43 5.40 5.41 5.33 5.57 5.33 4.76 5.47 4.63
d(H) for HꢀC(4) 5.50 5.52 6.12 6.20 5.92 5.94 6.06 6.05 5.62 6.07 5.66
4.69
5.81
)
b
3J(3,4) [Hz]
2.9
2.8
3.1
3.1
2.8
3.2
3.2
2.5
2.7
2.7
2.9a)
a) Only from HꢀC(3); HꢀC(4) appeared as a broad singlet. b) Both HꢀC(3) and HꢀC(4) appeared as
broad singlets.
Table 4. Chemical Shifts and Coupling Constants for 5H-Dihydrofuran Derivatives 8
8a
8f
8g
8i
8j
8l
8m
8o
8p
d(H) for HꢀC(4)
d(H) for HꢀC(5)
3J(4,5) [Hz]
5.95
6.19
1.4
6.24
6.51
1.5
6.24
6.61
1.5
6.15
6.65
1.5a)
6.21
6.65
1.5a)
5.88
6.11
1.5
6.38
6.72
1.5
5.62
6.31
1.5
5.63
6.42
1.5
a) Only from HꢀC(4); HꢀC(5) appeared as a broad singlet.
aryl groups yield naphthalenone derivatives as major products. In case of p-substituted
benzoyl and/or N-methyl p-substituted anilino groups (except for N-methyl-4-nitro-
aniline), quinoline derivatives were obtained almost as a sole product. These 5H-
dihydrofuran, naphthalenone, and quinoline derivatives are novel products which, to
the best of our knowledge, have not been observed in carbene reactions so far.
Experimental Part
General. All reactions of diazo compounds and enaminones were carried out under an atmosphere of
N2. A rotary evaporator equipped with a H2O condenser and attached to a vacuum system was used to
evaporate in vacuo. All solvents and reactants are commercially available. Dimethyl diazomalonate
(E2C¼N2, E ¼ CO2Me) was prepared by literature procedure [18]. FT-IR Spectra: Perkin-Elmer FT-IR

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Helvetica Chimica Acta – Vol. 94 (2011)
Spectrum One spectrometer. 1H- and 13C-NMR spectra: in CDCl3; chemical shifts (d) in ppm downfield
from TMS, at ambient temp., on 250- or 500-MHz and 60- or 125-MHz Bruker AC, resp. GC/MS: Hewlett-
Packard instrument equipped with a flame ionization detector; cross-linked (phenylmethyl)siloxane cap.
column (30 m ꢁ 0.32 mm ꢁ 0.25 mm) with He as the carrier gas (25 psi column head pressure); temp.
program: start 1008; then 5 min isothermal; ramp 208/min; final 2908, and then 10 min isothermal;
retention times (tR) in min.
Synthesis of Enaminones. Compounds 6a – 6i, and 6m – 6p were prepared by Procedure 1 (see
below), and 6k and 6l were prepared by a literature procedure [19].
Preparation of b-Keto Aldehyde Sodium Enolate. To soln. of NaH 80% (0.8 mol) in Et2O (400 ml)
was added MeOH (0.8 mol) at reflux temp. After addition, the mixture was refluxed for 10 min and
cooled at 08. The mixture of methyl ketone (0.8 mol) and methyl formate (0.84 mol) was added to the
mixture at 5 – 108 in 40 min. After addition of Et2O (200 ml), the mixture was stirred overnight. Then, the
mixture was filtered, and the precipitate was washed with Et2O (200 ml). b-Keto aldehyde sodium
enolate was dried in vacuo.
Preparation of b-Acylethenyl Chloride. b-Keto aldehyde sodium enolate (1 equiv.) was dissolved in
cold H2O and extracted with CH2Cl2. To the aq. layer was added 2n AcOH (1 equiv.), and the mixture
was extracted with CH2Cl2. The org. layer was washed with H2O and brine, and dried (MgSO4). The
solvent was removed in vacuo. The residue (b-keto aldehyde; 0.1 mol) was dissolved in benzene
(100 ml), and SOCl2 (0.11 mol) was added to this soln. The mixture was refluxed until HCl was no longer
evolved. The solvent was removed under reduced pressure, and the residue was distilled in vacuo. Yield
65%.
Procedure 1. To a soln. of a b-acylethenyl chloride (14 mmol) in benzene (50 ml) was added the
secondary amine (14 mmol) at r.t., and the mixture was refluxed until HCl was no longer evolved.
Benzene was removed in vacuo and the residue purified by recrystallization or distillation.
(2E)-3-[Methyl(4-nitrophenyl)amino]-1-phenylprop-2-en-1-one (6e). Recrystallized from benzene.
Yellow solid. Yield 65%. M.p. 132 – 1348. tR 18.38. IR (neat): 1642, 1543, 1503. 1H-NMR1): 8.31 (d, J ¼
12.8, 1 H); 8.25 (d, J ¼ 9.2, 2 H); 7.95 (d, J ¼ 8.3, 2 H); 7.56 – 7.42 (m, 3 H); 7.30 (d, J ¼ 9.2, 2 H); 6.34 (d,
J ¼ 12.8, 1 H). 13C-NMR (60 MHz): 189.3; 148.9; 146.2; 138.9; 133.6; 131.0; 129.9; 127.2; 126.7; 124.2;
119.9; 99.0; 37.6. EI-MS: 282 (Mþ, 50), 265 (100), 236 (10), 205 (15), 177 (27), 159 (27), 131 (62), 105
(32), 77 (39). HR-MS: 283.1080 (C16H15N2Oþ3 ; calc. 283.1083).
(2E)-3-[(4-Methoxyphenyl)(methyl)amino]-1-phenylprop-2-en-1-one (6f). Recrystallized from hex-
ane. Light yellow solid. M.p. 146 – 1488. tR 16.1. IR (neat): 3012, 2967, 1641, 1552, 1232. 1H-NMR: 8.12 (d,
J ¼ 12.5, 1 H); 7.92 (d, J ¼ 6.5, 2 H); 7.48 – 7.42 (m, 3 H); 7.13 (d, J ¼ 8.8, 2 H); 6.90 (d, J ¼ 8.8, 2 H); 6.00
(d, J ¼ 12.5, 1 H); 3.81 (s, 3 H); 3.36 (s, 3 H). 13C-NMR2): 188.3; 156.3; 149.8; 139.3; 130.2; 127.2; 126.6;
121.6; 113.7; 108.8; 95.0; 54.6; 31.1. EI-MS: 267 (100, Mþ), 251 (95), 190 (27), 162 (94), 147 (54), 105
(48), 77 (44). HR-MS: 268.1340 (C17H18NOþ2 ; calc. 268.1338).
(2E)-3-[Methyl(4-methylphenyl)amino]-1-phenylprop-2-en-1-one (6g). Recrystallized from hexane.
Yellow-orange solid. M.p. 109 – 1118. tR 15.3. IR (neat): 3057, 2982, 1634, 1545, 1254, 1313. 1H-NMR: 8.19
(d, J ¼ 12.7, 1 H); 7.93 (d, J ¼ 6.6, 2 H); 7.48 – 7.43 (m, 3 H); 7.18 (d, J ¼ 8.2, 2 H); 7.09 (d, J ¼ 8.3, 2 H);
6.05 (d, J ¼ 12.7, 1 H); 3.37 (s, 3 H); 2.34 (s, 3 H). 13C-NMR: 188.4; 149.3; 139.2; 133.9; 130.2; 129.1; 127.2;
126.7; 119.6; 95.5; 30.7; 19.7. EI-MS: 251 (70, Mþ), 234 (90), 174 (54), 146 (100), 131 (43), 105 (41), 77
(34). HR-MS: 252.1385 (C17H17NOþ; calc. 252.1388).
(2E)-1-(4-Methoxyphenyl)-3-[methyl(phenyl)amino]prop-2-en-1-one (6i). Recrystallized from
1
AcOEt. Yellow solid. M.p. 194 – 1988. tR 16.4. IR (neat): 3005, 2667, 1641, 1552, 1240. H-NMR: 8.21
(d, J ¼ 12.7, 1 H); 7.94 (d, J ¼ 8.7, 2 H); 7.39 – 7.33 (m, 2 H); 7.21 – 7.12 (m, 3 H); 6.92 (d, J ¼ 8.7, 2 H); 6.09
(d, J ¼ 12.7, 1 H); 3.85 (s, 3 H); 3.38 (s, 3 H). 13C-NMR: 187.1; 161.4; 148.4; 145.5; 131.7; 130.2; 122.7;
119.4; 112.9; 112.5; 95.6; 58.5; 37.2. EI-MS: 267 (53, Mþ), 250 (100), 236 (5), 160 (23), 132 (75), 77 (32).
HR-MS: 268.1344 (C17H17NOþ2 ; calc. 268.1338).
(2E)-1-(4-Methylphenyl)-3-[methyl(phenyl)amino]prop-2-en-1-one (6j). Recrystallized from hex-
1
ane. Orange solid. M.p. 134 – 1368. tR 14.3. H-NMR (500 MHz): 8.14 (d, J ¼ 12.7, 1 H); 7.78 (d, J ¼ 7.8,
1
)
)
If not stated otherwise at 250 MHz.
If not stated otherwise at 125 MHz.
2

Helvetica Chimica Acta – Vol. 94 (2011)
1125
2 H); 7.30 (t, J ¼ 7.8, 2 H); 7.18 – 7.14 (m, 4 H); 7.09 (td, J ¼ 7.3, 1, 1 H); 6.03 (d, J ¼ 12.7, 1 H); 3.32 (s,
3 H); 2.33 (s, 3 H). 13C-NMR: 188.1; 148.7; 145.5; 140.8; 136.4; 128.5; 127.9; 126.8; 123.8; 119.4; 95.9;
36.8; 20.5. EI-MS: 251 (40, Mþ), 234 (59), 160 (30), 132 (100), 91 (46), 77 (37). HR-MS: 252.1390
(C17H17NOþ; calc. 252.1388).
(2E)-3-[Methyl(phenyl)amino]-1-(naphthalen-2-yl)prop-2-en-1-one (6m). Dissolved in benzene
and precipitated in hexane. Grey solid. M.p. 107 – 1098. tR 16.7. IR (neat): 3050, 2960, 1641, 1530, 1247,
1083. 1H-NMR (500 MHz): 8.36 (br. s, 1 H); 8.21 (d, J ¼ 12.7, 1 H); 7.97 (dd, J ¼ 8.5, 1.7, 1 H); 7.88 (d,
J ¼ 7.8, 1 H); 7.81 (d, J ¼ 8.8, 1 H); 7.79 (d, J ¼ 8.5, 1 H); 7.45 (dquint., J ¼ 7.3, 1.6, 2 H); 7.31 (td, J ¼ 7.0,
1.6, 2 H); 7.16 (td, J ¼ 8.0, 1.2, 2 H); 7.10 (t, J ¼ 7.3, 1 H); 6.18 (d, J ¼ 12.7, 1 H); 3.36 (s, 3 H). 13C-NMR:
188.2; 149.0; 145.5; 136.4; 133.9; 131.8; 128.5; 128.2; 127.3; 127.0; 126.7; 126.5; 125.3; 124.0; 123.6; 119.5;
96.1; 36.4. EI-MS: 287 (70, Mþ), 270 (100), 182 (8), 160 (34), 132 (75), 77 (30). HR-MS: 288.1380
(C20H17NOþ; calc. 288.1388).
(3E)-4-[Methyl(phenyl)amino]but-3-en-2-one (6n). Synthesized by a literature procedure [20].
1H-NMR: 7.83 (d, J ¼ 13.1, 1 H); 7.30 (t, J ¼ 7.8, 3 H); 7.08 (d, J ¼ 8.3, 2 H); 5.36 (d, J ¼ 13.1, 1 H); 3.20 (s,
3 H); 2.13 (s, 3 H).
(3E)-4-[(4-Methoxyphenyl)(methyl)amino]but-3-en-2-one (6o). Recrystallized from hexane. Yel-
low solid. M.p. 146 – 1488. tR 12.8. IR (neat): 3057, 2967, 1664, 1552, 1500, 1240. 1H-NMR: 7.74 (d, J ¼ 13.0,
1 H); 7.03 (d, J ¼ 8.9, 2 H); 6.84 (d, J ¼ 8.9, 2 H); 5.29 (d, J ¼ 13.0, 1 H); 3.76 (s, 3 H); 3.19 (s, 3 H); 2.12
(s, 3 H). 13C-NMR (60 MHz): 185.4; 153.3; 149.0; 140.2; 116.2; 114.1; 106.6; 46.9; 46.8; 29.0. EI-MS: 205
(95, Mþ), 190 (100), 162 (60), 147 (97), 121 (24), 77 (12). HR-MS: 206.1175 (C12H15NOþ2 ; calc.
206.1181).
(3E)-4-[Methyl(4-methylphenyl)amino]but-3-en-2-one (6p). Recrystallized from hexane. Orange
solid. M.p. 109 – 1118. tR 11.2. IR (neat): 3027, 2915, 1664, 1596, 1552, 1508, 1336, 1254. 1H-NMR: 7.79 (d,
J ¼ 13.1, 1 H); 7.08 (d, J ¼ 8.0, 2 H); 6.96 (d, J ¼ 8.0, 2 H); 5.31 (d, J ¼ 13.1, 1 H); 3.17 (s, 3 H); 2.25 (s,
3 H); 2.11 (s, 3 H). 13C-NMR (60 MHz): 196.0; 148.7; 144.1; 134.6; 130.0; 120.4; 101.2; 37.2; 28.1; 20.7. EI-
MS: 205 (95, Mþ), 190 (100), 162 (60), 147 (97), 121 (24), 77 (12). HR-MS: 190.1234 (C12H15NOþ; calc.
190.1232).
(2E)-3-(Dimethylamino)-1-(3-nitrophenyl)prop-2-en-1-one (6k). Recrystallized from hexane.
1
Brown solid. M.p. 70 – 738. tR 14.3. H-NMR: 8.68 (br. s, 1 arom. H); 8.27 (ttt, J ¼ 9.1, ca. 2, 2 H); 7.88
(d, J ¼ 12.2, 1 H); 7.58 (t, J ¼ 7.9, 1 H); 5.70 (d, J ¼ 12.2, 1 H); 3.19 (s, 3 H); 2.98 (s, 3 H). 13C-NMR
(60 MHz): 185.4; 155.2; 148.2; 142.1; 133.4; 129.2; 125.3; 122.3; 91.3; 45.2; 37.5. EI-MS: 220 (43, Mþ), 203
(100), 157 (12), 98 (73), 70 (13). HR-MS: 221.0100 (C11H12N2Oþ3 ; calc. 221.0926).
(2E)-3-(Dimethylamino)-1-(3-methoxyphenyl)prop-2-en-1-one (6l). 1H-NMR: 7.77 (d, J ¼ 12.3,
1 H); 7.45 (br. s, 2 H); 7.29 (t, J ¼ 8.1, 1 H); 6.98 (d, J ¼ 7.8, 1 H); 5.67 (d, J ¼ 12.3, 1 H); 3.83 (s,
3 H); 3.10 (br. s, 3 H); 2.90 (br. s, 3 H).
General Procedure for the Reaction of Enaminones with Dimethyl Diazomalonate. To a soln. of 6
(2.1 mmol) in benzene (10 ml) was added Cu(acac)2 (9 ꢁ 10ꢀ3 mmol), and the mixture was heated at
reflux temp. A soln. of E2C¼N2 (1.4 mmol) in benzene (4 ml) was added to this soln. over 2.5 h under N2.
When the IR spectrum of the mixture indicated total consumption of E2C¼N2 (absence of the
characteristic diazo band at 2130 cmꢀ1), the mixture was filtered, evaporated, and purified by CC or prep.
TLC. The crude mixture contained varying amounts of unidentified compounds (max. 20% by GC).
Dimethyl 3-[Methyl(4-nitrophenyl)amino]-5-phenylfuran-2,2(3H)-dicarboxylate (7e). Isolated by
CC (neutral alumina; hexane/AcOEt 4 :1). Colorless solid. M.p. 167 – 1708. tR 21.63. IR (neat): 1730,
1592, 1383, 1229. 1H-NMR: 8.15 (dd, J ¼ 7.3, 2.2, 2 H); 7.73 – 7.69 (m, 2 H); 7.44 – 7.37 (m, 3 H); 6.97 (dd,
J ¼ 7.4, 2.1, 2 H); 6.20 (d, J ¼ 3.1, 1 H); 5.40 (d, J ¼ 3.1, 1 H); 3.88 (s, 3 H); 3.46 (s, 3 H); 2.85 (s, 3 H).
13C-NMR: 167.8; 165.5; 158.2; 153.6; 137.4; 131.5; 129.5; 128.8; 127.2; 124.6; 113.3; 95.8; 92.9; 69.7; 52.8;
51.7; 32.2. EI-MS: 412 (1, Mþ), 261 (100), 217 (61), 202 (38), 171 (23), 115 (16), 59 (7). HR-MS: 413.1351
(C21H20N2Oþ7 ; calc. 413.1349).
Dimethyl 3-[(4-Methoxyphenyl)(methyl)amino]-5-phenylfuran-2,2(3H)-dicarboxylate (7f). Purified
by CC (neutral alumina; hexane/AcOEt 4 :1). Yellowish solid. tR 16.94. IR (neat): 2982, 2960, 1738, 1508,
1083. 1H-NMR: 7.69 – 7.68 (m, 2 H); 7.39 – 7.37 (m, 3 H); 6.92 (d, J ¼ 9.2, 2 H); 6.84 (d, J ¼ 9.1, 2 H); 5.92
(d, J ¼ 2.7, 1 H); 5.41 (d, J ¼ 2.9, 1 H); 3.85 (s, 3 H); 3.76 (s, 3 H); 3.55 (s, 3 H); 2.71 (s, 3 H). 13C-NMR:
167.2; 165.0; 155.6; 151.3; 143.0; 128.6; 128.2; 127.4; 125.0; 114.2; 113.5; 94.6; 90.7; 69.9; 54.7; 52.5; 52.4;

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Helvetica Chimica Acta – Vol. 94 (2011)
32.3. EI-MS: 397 (37, Mþ), 338 (44), 261 (100), 217 (72), 185 (76), 171 (32), 129 (31), 115 (23), 59 (13).
HR-MS: 398.1601 (C22H23NOþ6 ; calc. 398.1604). The structure of 7f was finally established by an X-ray
crystal-structure analysis (Fig. 3)3).
Dimethyl 3-[Methyl(4-methylphenyl)amino]-5-phenylfuran-2,2(3H)-dicarboxylate (7g). The prod-
uct was isolated by CC on neutral alumina (hexane/AcOEt 8 :1) as a dark yellow oil. tR 16.14 min. IR
(neat): 3027, 2960, 1738, 1515. 1H-NMR (500 MHz): 7.63 (dd, J ¼ 7.6, 2.2, 2 H); 7.33 – 7.30 (m, 3 H); 6.91
(d, J ¼ 8.3, 2 H); 6.80 (d, J ¼ 8.8, 2 H); 5.94 (d, J ¼ 3.4, 1 H); 5.33 (d, J ¼ 2.9, 1 H); 3.79 (s, 3 H); 3.47 (s,
3 H); 2.66 (s, 3 H); 2.19 (s, 3 H). 13C-NMR: 167.2; 165.0; 155.7; 146.3; 128.6; 128.5; 128.2; 127.4; 126.0;
125.0; 112.8; 94.6; 90.5; 69.2; 52.5; 51.6; 32.0; 19.3. EI-MS: 381 (16, Mþ), 322 (41), 261 (100), 217 (66),
185 (70), 171 (33), 129 (29), 115 (23), 91 (26), 59 (15). HR-MS: 382.1652 (C22H23NOþ5 ; calc. 382.1654).
Dimethyl 3-[Methyl(phenyl)amino]-5-(4-nitrophenyl)furan-2,2(3H)-dicarboxylate (7h). Purifica-
tion by prep. TLC (alumina plate; hexane/AcOEt 6 :1). Red oil. tR 16.47. 1H-NMR (500 MHz): 8.19 (dd,
J ¼ 8.8, 2.0, 2 H); 7.79 (dd, J ¼ 8.8, 2.0, 2 H); 7.23 – 7.22 (m, 2 H); 6.91 (d, J ¼ 8.3, 2 H); 6.74 (t, J ¼ 7.3,
1 H); 6.06 (d, J ¼ 2.9, 1 H); 5.57 (d, J ¼ 3.4, 1 H); 3.82 (s, 3 H); 3.46 (s, 3 H); 2.69 (s, 3 H). 13C-NMR:
166.7; 164.5; 153.6; 148.0; 147.3; 133.9; 128.0; 125.8; 122.8; 117.3; 112.7; 108.8; 99.0; 68.8; 51.9; 28.7. EI-
MS: 412 (4, Mþ), 394 (12), 353 (47), 306 (45), 262 (100), 231 (42), 106 (46), 77 (48), 59 (36). HR-MS:
413.1352 (C21H20N2Oþ7 ; calc. 413.1349).
Dimethyl 5-(4-Methylphenyl)-3-[methyl(phenyl)amino]furan-2,2(3H)-dicarboxylate (7j). Purifica-
1
tion by prep. TLC (alumina plate; hexane/AcOEt 5 :1). Yellow oil. tR 14.98. H-NMR: 7.59 (d, J ¼ 7.9,
2 H); 7.28 – 7.18 (m, 3 H); 6.97 (d, J ¼ 8.1, 2 H); 6.76 (t, J ¼ 7.1, 2 H); 6.05 (d, J ¼ 2.4, 1 H); 5.33 (d, J ¼2.7,
1 H); 3.85 (s, 3 H); 3.49 (s, 3 H); 2.74 (s, 3 H); 2.37 (s, 3 H). 13C-NMR: 167.2; 165.0; 156.0; 148.3; 138.9;
128.1; 128.0; 125.4; 125.0; 116.7; 112.5; 93.7; 90.4; 68.7; 52.5; 51.6; 31.8; 20.4. EI-MS: 381 (2, Mþ), 275
(100), 231 (70), 216 (74), 185 (43), 129 (54), 77 (95), 59 (47). HR-MS: 382.1652 (C22H23NOþ5 ; calc.
382.1654).
Dimethyl 3-(Dimethylamino)-5-(3-nitrophenyl)furan-2,2(3H)-dicarboxylate (7k). Isolated by CC
1
(neutral alumina; hexane/AcOEt 9 :1). Red-brown oil. tR 14.50. H-NMR (500 MHz): 8.41 (t, J ¼ 1.71,
1 H); 8.12 (ddd, J ¼ 8.3, 2.4, 1, 1 H); 7.91 (dt, J ¼ 8.3, 1.3, 1 H); 7.48 (t, J ¼ 8.1, 1 H); 5.62 (d, J ¼ 2.9, 1 H);
4.76 (d, J ¼ 2.4, 1 H); 3.77 (s, 3 H); 3.74 (s, 3 H); 2.27 (s, 6 H). 13C-NMR: 166.9; 165.0; 153.0; 130.5; 130.1;
128.5; 122.8; 119.9; 108.8; 96.3; 91.6; 72.5; 52.5; 51.8; 40.9. EI-MS: 350 (8, Mþ), 306 (16), 291 (100), 262
(46), 231 (24), 157 (8), 115 (12), 59 (7). HR-MS: 351.1189 (C16H18N2Oþ7 ; calc. 351.1192).
Dimethyl 5-Methyl-3-[methyl(4-methylphenyl)amino]furan-2,2(3H)-dicarboxylate (7p) and Di-
methyl (Methylamino)(4-methylphenyl)propanedioate (13). Purified by CC (SiO2; hexane/AcOEt
1
80 :20). Compounds 7p and 13 were obtained as a mixture (1:1 from H-NMR).
Data of 7p. tR 13.3 (from the mixture of 7p and 13). 1H-NMR (from the mixture of 7p and 13): 6.81
(d, J ¼ 7.9, 1 H); 6.71 (d, J ¼ 7.9, 1 H); 5.81 (br. s, 1 H); 4.69 (br. s, 1 H); 3.84 (s, 3 H); 3.48 (s, 3 H); 2.65
(s, 3 H); 2.23 (s, 3 H); 1.98 (s, 3 H). 13C-NMR: 167.19; 167.18; 155.4; 146.4; 128.8; 128.4; 112.9; 95.6; 90.6;
69.1; 51.6; 51.5; 34.8; 19.2; 12.6. EI-MS: 319 (29, Mþ), 199 (18), 155 (100), 121 (92), 91 (28), 59 (18).
Data of 13. tR 11.7 (from the mixture of 7p and 13). 1H-NMR (from the mixture of 7p and 13): 7.06 –
7.01 (m, 4 H); 5.10 (br. s, 1 H); 3.78 (s, 6 H); 3.00 (s, 3 H); 2.23 (s, 3 H). 13C-NMR: 165.2; 145.8; 127.2;
125.8; 112.7; 65.2; 52.4; 31.7; 19.3. EI-MS: 251 (21, Mþ), 192 (100), 132 (11), 118 (14), 91 (14), 59 (3).
Dimethyl 5-(Dimethylamino)-3-phenylfuran-2,2(5H)-dicarboxylate (8a). Purification by CC (neu-
tral alumina; hexane/AcOEt 72 :28). A fraction from the column was further chromatographed on a
prep. alumina TLC plate (hexane/AcOEt 72 :28). Compound 8a was obtained as a light red oil. tR 12.75.
IR (neat): 2982, 1731, 1440, 1075. 1H-NMR: 7.42 (dd, J ¼ 6.6, 3.2, 2 H); 7.33 – 7.29 (m, 3 H); 6.19 (d, J ¼
1.4, 1 H); 5.95 (d, J ¼ 1.4, 1 H); 3.77 (s, 3 H); 3.73 (s, 3 H); 2.41 (s, 6 H). 13C-NMR: 168.0; 166.2; 141.7;
132.5; 128.10; 127.3; 127.7; 126.8; 102.9; 102.1; 52.6; 51.1; 38.4. EI-MS: 305 (13, Mþ), 261 (89), 246 (100),
185 (60), 172 (31), 158 (53), 115 (38), 59 (8). HR-MS: 306.1343 (C16H19NOþ5 ; calc. 306.1341).
Dimethyl 5-[(4-Methoxyphenyl)(methyl)amino]-3-phenylfuran-2,2(5H)-dicarboxylate (8f). Purified
by CC (neutral alumina; hexane/AcOEt 85 :15). Compound 8f was obtained as a mixture with 7f
3
)
CCDC-774461 (for 7f) and -774462 (for 10n) contain the supplementary crystallographic data for
this article. These data can be obtained free of charge from the Cambridge Crystallographic Data
Center via www.ccdc.cam.ac.uk/data_request/cif.

Helvetica Chimica Acta – Vol. 94 (2011)
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1
(1.58 :0.68 from H-NMR). tR 17.4. H-NMR: 7.40 – 7.39 (m, 1 H); 7.27 – 7.26 (m, 2 H); 6.99 (d, J ¼ 8.3,
2 H); 6.85 (d, J ¼ 7.6, 2 H); 6.78 (d, J ¼ 8.8, 2 H); 6.51 (d, J ¼ 1.5, 1 H); 6.24 (d, J ¼ 1.5, 1 H); 3.79 (s,
3 H); 3.70 (s, 3 H); 3.69 (s, 3 H); 2.77 (s, 3 H). EI-MS: 397 (36, Mþ), 338 (47), 261 (100), 217 (69), 185
(71), 171 (36), 129 (33), 115 (27), 77 (16), 59 (8).
Dimethyl 5-[Methyl(4-methylphenyl)amino]-3-phenylfuran-2,2(5H)-dicarboxylate (8g). Purifica-
tion of the mixture was realized on neutral alumina CC (hexane/AcOEt 80 :20). A fraction from the
column was further chromatographed on a prep. alumina TLC plate (hexane/AcOEt 80 :20). Compound
8g was obtained as a mixture with 7g (8g/7g 1:9 from 1H-NMR). This mixture gave only one peak in GC.
Data of 8g. tR 16.1 (from the mixture). 1H-NMR (500 MHz): 7.42 – 7.40 (m, 3 H); 7.27 – 7.26 (m, 2 H);
7.01 (d, J ¼ 8.8, 2 H); 6.92 (d, J ¼ 8.3, 2 H); 6.61 (d, J ¼ 1.5, 1 H); 6.24 (d, J ¼ 1.5, 1 H); 3.69 (s, 3 H); 3.68
(s, 3 H); 2.79 (s, 3 H); 2.21 (s, 3 H). EI-MS: 381 (16, Mþ), 322 (41), 261 (100), 217 (66), 185 (70), 171
(33), 129 (29), 115 (23), 91 (26), 59 (15).
Dimethyl 3-(4-Methoxyphenyl)-5-[methyl(phenyl)amino]furan-2,2(5H)-dicarboxylate (8i). Purified
by CC (neutral alumina; hexane/AcOEt 80 :20). Compound 8i was obtained as a mixture with 6i (8i/6i
3 :1 from 1H-NMR).
1
Data of 8i. tR 17.4. H-NMR (500 MHz): 7.38 (d, J ¼ 8.8, 2 H); 7.22 – 7.18 (m, 3 H); 6.99 (d, J ¼ 8.3,
2 H); 6.81 – 6.79 (m, 2 H); 6.65 (br. s, 1 H); 6.15 (d, J ¼ 1.5, 1 H); 3.79 (s, 3 H); 3.74 (s, 3 H); 3.69 (s, 3 H);
2.81 (s, 3 H). 13C-NMR: 168.0; 166.9; 159.0; 148.3; 140.2; 128.7; 128.2; 128.1; 124.9; 119.1; 115.7; 112.7;
97.1; 90.4; 54.3; 52.0; 51.8; 31.7. EI-MS: 397 (1, Mþ), 338 (17), 291 (100), 250 (20), 215 (30), 187 (15), 159
(12), 145 (8), 77 (11), 59 (5).
Dimethyl 3-(4-Methylphenyl)-5-[methyl(phenyl)amino]furan-2,2(5H)-dicarboxylate (8j). Purifica-
tion by prep. TLC (alumina plate; hexane/AcOEt 80 :20). Compound 8j was obtained as a mixture with
7j (8j/7j 1.79 :1 from 1H-NMR).
Data of 8j. tR 14.9. 1H-NMR (500 MHz): 7.31 (d, J ¼ 7.8, 2 H); 7.22 – 7.20 (m, 2 H); 7.08 (d, J ¼ 7.8,
2 H); 7.00 (d, J ¼ 8.3, 2 H); 6.82 (t, J ¼ 7.0, 1 H); 6.65 (br. s, 1 H); 6.21 (d, J ¼ 1.46, 1 H); 3.70 (s, 3 H); 3.60
(s, 3 H); 2.82 (s, 3 H); 2.28 (s, 3 H). 13C-NMR: 169.2; 168.1; 149.5; 141.9; 139.1; 129.3; 129.2; 128.6; 128.0;
126.2; 120.38; 116.93; 98.3; 91.8; 53.2; 53.0; 33.0; 21.5. EI-MS: 381 (1, Mþ), 322 (7), 275 (28), 198 (19),
143 (14), 119 (100), 91 (35), 77 (23).
Dimethyl 5-(Dimethylamino)-3-(3-methoxyphenyl)furan-2,2(5H)-dicarboxylate (8l). Isolated by
CC (neutral alumina; hexane/AcOEt 85 :15). tR 13.7. IR (neat): 2975, 1738, 1596. 1H-NMR (500 MHz):
7.16 (t, J ¼ 8.0, 1 H); 6.95 (d, J ¼ 7.6, 1 H); 6.94 (d, J ¼ 1.5, 1 H); 6.79 (dtd, J ¼ 8.7, 2.4, 1.2, 1 H); 6.11 (d,
J ¼ 1.5, 1 H); 5.88 (d, J ¼ 1.5, 1 H); 3.73 (s, 3 H); 3.71 (s, 3 H); 3.68 (s, 3 H); 2.35 (s, 6 H). 13C-NMR: 168.1;
166.9; 158.3; 141.0; 140.0; 128.2; 128.1; 119.4; 113.1; 112.8; 102.4; 54.2; 51.9; 51.7; 38.4. EI-MS: 335 (21,
Mþ), 291 (90), 276 (100), 247 (40), 187 (46), 159 (19), 115 (11), 82 (20), 59 (7). HR-MS: 336.1450
(C17H21NOþ6 ; calc. 336.1447).
Dimethyl 5-[Methyl(phenyl)amino]-3-(naphthalen-2-yl)furan-2,2(5H)-dicarboxylate (8m). Purifi-
cation by prep. TLC (alumina plate; hexane/AcOEt 80 :20). Compound 8m was obtained as a mixture
with 7m (8m/7m 4 :1, from 1H-NMR). This mixture gave one peak on GC. tR 17.37. 1H-NMR (500 MHz,
4 :1 mixture with 7m): 7.89 (br. s, 1 H); 7.78 – 7.73 (m, 3 H); 7.54 (dd, J ¼ 8.5, 1.7, 1 H); 7.43 – 7.41 (m,
2 H); 7.22 (td, J ¼ 8.0, 1.0, 2 H); 7.03 (dd, J ¼ 8.8, 1.0, 2 H); 6.84 (t, J ¼ 6.4, 1 H); 6.72 (d, J ¼ 1.5, 1 H);
6.38 (d, J ¼ 1.5, 1 H); 3.713 (s, 3 H); 3.711 (s, 3 H); 2.86 (s, 3 H). 13C-NMR: 168.0; 166.9; 148.3; 140.8;
140.6; 132.3; 132.0; 128.1; 127.6; 127.4; 126.9; 126.6; 126.5; 125.8; 125.4; 124.3; 119.3; 115.8; 97.2; 90.6;
52.0; 51.9; 31.9. EI-MS: 417 (2, Mþ), 399 (9), 368 (19), 311 (100), 270 (33), 235 (43), 207 (35), 179 (30),
77 (14), 59 (8).
Dimethyl 3-[(4-Methoxyphenyl)(methyl)amino]-5-methylfuran-2,2(3H)-dicarboxylate (7o) and Di-
methyl 5-[(4-Methoxyphenyl)(methyl)amino]-3-methylfuran-2,2(5H)-dicarboxylate (8o). The mixture
was purified by CC (neutral alumina; hexane/AcOEt 80 :20). Compounds 7o and 8o were obtained as a
mixture (7o/8o 1:2, from 1H-NMR) as a yellow oil.
Data of 7o. tR 13.95. 1H-NMR (500 MHz, 1:2 mixture with 8o): 6.79 (dt, J ¼ 6.8, 2.9, 2 H); 6.74 (dt,
J ¼ 8.1, 2.9, 2 H); 5.66 (br. s, 1 H); 4.63 (dq, J ¼ 2.9, 1.4, 1 H); 3.77 (s, 3 H); 3.67 (s, 3 H); 3.44 (s, 3 H);
2.58 (s, 3 H); 1.90 (t, J ¼ 1.7, 3 H). 13C-NMR: 167.2; 165.2; 155.3; 151.2; 143.1; 114.0; 113.4; 91.0; 90.7;
69.8; 54.7; 52.4; 51.5; 32.0; 12.6. EI-MS: 335 (Mþ, 36), 276 (32), 155 (81), 137 (100), 109 (40), 59 (33).

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Helvetica Chimica Acta – Vol. 94 (2011)
Data of 8o. tR 14.1. 1H-NMR (500 MHz, 2 :1 mixture with 7o): 6.93 (dd, J ¼ 6.83, 1.96, 2 H); 6.74 (dt,
J ¼ 8.1, 2.9, 2 H); 6.31 (d, J ¼ 1.5, 1 H); 5.62 (d, J ¼ 1.5, 1 H); 3.71 (s, 3 H); 3.70 (s, 3 H); 3.67 (s, 3 H); 2.65
(s, 3 H); 1.90 (t, J ¼ 1.7, 3 H). 13C-NMR: 167.8; 166.8; 153.3; 142.5; 137.1; 126.1; 118.9; 113.4; 98.7; 95.5;
54.6; 51.8; 51.6; 32.6; 11.9. EI-MS: 335 (56, Mþ), 276 (75), 155 (100), 137 (44), 109 (42), 59 (17).
Dimethyl 3-Methyl-5-[methyl(4-methylphenyl)amino]furan-2,2(5H)-dicarboxylate (8p). Purified by
CC (SiO2; hexane/AcOEt 85 :15). Yellow oil. tR 12.69 min. IR (neat): 2982, 2878, 1746, 1523, 1269.
1H-NMR (500 MHz): 6.98 (d, J ¼ 8.8, 2 H); 6.87 (d, J ¼ 8.8, 2 H); 6.42 (d, J ¼ 1.5, 1 H); 5.63 (d, J ¼ 1.5,
1 H); 3.73 (s, 3 H); 3.70 (s, 3 H); 2.68 (s, 3 H); 2.19 (s, 3 H); 1.92 (s, 3 H). 13C-NMR: 167.7; 166.8; 146.1;
137.2; 128.6; 128.5; 126.0; 116.3; 97.7; 91.0; 51.8; 51.7; 31.7; 19.4; 11.9. EI-MS: 319 (24, Mþ), 260 (44), 199
(36), 155 (100), 121 (57), 91 (33), 59 (36). HR-MS: 320.1503 (C17H21NOþ5 ; calc. 320.1498).
Dimethyl 2-[Methyl(phenyl)amino]-4-oxoanthracene-1,1(4H)-dicarboxylate (9m). Isolated by prep.
TLC (alumina plate; hexane/AcOEt 85 :15). Light yellow oil. tR 20.56. 1H-NMR (500 MHz): 8.02 (br. s,
1 H); 7.85 – 7.81 (m, 2 H); 7.65 (d, J ¼ 8.8, 1 H); 7.49 (dquint., J ¼ 7.6, 1.5, 2 H); 7.27 (td, J ¼ 7.4, 1.5, 2 H);
7.16 (s, 1 H); 7.10 (t, J ¼ 7.5, 1 H); 6.89 (d, J ¼ 8.3, 1 H); 3.72 (s, 6 H); 3.24 (s, 3 H). 13C-NMR: 192.2;
169.5; 145.9; 135.9; 135.4; 133.3; 131.5; 129.4; 128.0; 127.8; 127.5; 127.2; 126.8; 126.2; 123.1; 120.2; 112.2;
109.0; 56.0; 52.16; 52.15; 38.8. HR-MS: 416.1495 (C25H21NOþ5 ; calc. 416.1498).
Dimethyl 3-Benzoyl-6-methoxy-1-methylquinoline-4,4(1H)-dicarboxylate (10f). Purified by CC
(neutral alumina; hexane/AcOEt 85 :15). tR 19.77. IR (neat): 2982, 2870, 1723, 1455, 1075. 1H-NMR
(500 MHz): 7.52 (dt, J ¼ 6.4, 1.7, 2 H); 7.39 (tt, J ¼ 7.3, 1.5, 1 H); 7.35 (tt, J ¼ 7.3, 1.5, 2 H); 7.08 (s, 1 H); 7.06
(t, J ¼ 1.7, 1 H); 6.82 (d, J ¼ 1.5, 2 H); 3.74 (s, 3 H); 3.68 (s, 6 H); 3.23 (s, 3 H). 13C-NMR: 192.0; 169.4;
145.0; 138.8; 129.3; 129.2; 127.5; 127.2; 121.4; 114.2; 114.1; 113.3; 107.5; 56.1; 54.7; 52.4; 38.9. EI-MS: 395
(2, Mþ), 336 (100), 234 (5), 173 (4), 105 (3), 77 (4). HR-MS: 396.1450 (C22H21NOþ6 ; calc. 396.1447).
Dimethyl 3-Benzoyl-1,6-dimethylquinoline-4,4(1H)-dicarboxylate (10g). Purified by CC (neutral
alumina; hexane/AcOEt 80 :20). tR 18.36. IR (neat): 3057, 2982, 1634, 1545, 1254. 1H-NMR (500 MHz):
7.52 (dt, J ¼ 6.3, 1.5, 2 H); 7.39 (tt, J ¼ 7.3, 1.5, 1 H); 7.35 (tt, J ¼ 7.3, 1.5, 2 H); 7.28 (br. s, 1 H); 7.08 (s, 1 H);
7.06 (dq, J ¼ 8.3, 1.0, 1 H); 6.77 (d, J ¼ 8.3, 1 H); 3.69 (s, 6 H); 3.23 (s, 3 H); 2.27 (s, 3 H). 13C-NMR: 192.1;
169.6; 145.7; 138.7; 133.1; 132.9; 129.6; 129.3; 128.8; 127.5; 127.1; 120.0; 112.2; 108.4; 55.8; 52.4; 52.1; 38.8;
19.8. EI-MS: 379 (1, Mþ), 320 (100), 260 (4), 157 (5), 105 (3), 77 (4). HR-MS: 379.1416 (C22H21NOþ5 ;
calc. 379.1420).
Dimethyl 1-Methyl-3-(4-nitrobenzoyl)quinoline-4,4(1H)-dicarboxylate (10h). Isolated by prep. TLC
(alumina plate; hexane/AcOEt 80 :20). White solid. M.p. 127 – 1298. tR 18.64. IR (neat): 3067, 3007, 2953,
1739, 1644, 1521, 1482, 1336. 1H-NMR (500 MHz): 8.28 (d, J ¼ 8.5, 2 H); 7.73 (d, J ¼ 8.5, 2 H); 7.55 (d, J ¼
7.8, 1 H); 7.35 (t, J ¼ 7.7, 1 H); 7.18 (t, J ¼ 7.5, 1 H); 7.03 (s, 1 H); 6.97 (d, J ¼ 8.2, 1 H); 3.75 (s, 6 H); 3.34 (s,
3 H). 13C-NMR: 190.0; 169.2; 147.8; 146.1; 144.5; 135.0; 129.5; 128.3; 123.6; 122.5; 120.1; 112.5; 108.7;
55.7; 52.2; 39.1. EI-MS: 410 (1, Mþ), 351 (100), 305 (14), 143 (5). HR-MS: 411.1194 (C21H18N2Oþ7 ; calc.
411.1192).
Dimethyl 3-(4-Methoxybenzoyl)-1-methylquinoline-4,4(1H)-dicarboxylate (10i). Purified by CC
(neutral alumina; hexane/AcOEt 80 :20). Colorless solid. M.p. 198 – 2008. tR 21.59. 1H-NMR (500 MHz):
7.53 (d, J ¼ 8.3, 2 H); 7.46 (dd, J ¼ 7.8, 1.0, 1 H); 7.24 (td, J ¼ 7.8, 1.0, 1 H); 7.11 (s, 1 H); 7.05 (t, J ¼ 7.5,
1 H); 6.86 (d, J ¼ 6.8, 1 H); 6.85 (d, J ¼ 8.8, 1 H); 3.77 (s, 3 H); 3.65 (s, 6 H); 3.24 (s, 3 H). 13C-NMR:
191.4; 169.6; 160.7; 145.0; 135.5; 131.0; 129.7; 129.3; 128.0; 122.8; 120.1; 112.5; 112.2; 108.5; 56.1; 54.4;
52.0; 38.8. EI-MS: 395 (3, Mþ), 336 (100), 143 (16), 77 (3). HR-MS: 396.1451 (C22H21NOþ6 ; calc.
396.1447).
Dimethyl 3-Acetyl-1-methylquinoline-4,4(1H)-dicarboxylate (10n). Purified by CC (neutral alumina;
hexane/AcOEt 85 :15). Colorless solid. M.p. 216 – 2188. tR 14.77. IR (neat): 3087, 2982, 2945, 1731, 1626,
1567, 1478. 1H-NMR: 7.47 (d, J ¼ 6.9, 1 H); 7.40 (s, 1 H); 7.30 (t, J ¼ 7.8, 1 H); 7.10 (t, J ¼ 7.7, 1 H); 6.93
(d, J ¼ 8.3, 1 H); 3.69 (s, 6 H); 3.41 (s, 3 H); 2.32 (s, 3 H). 13C-NMR (60 MHz): 190.0; 170.5; 143.5; 136.4;
130.2; 129.0; 123.8; 121.0; 113.1; 110.7; 53.0; 39.8; 24.3. EI-MS: 303 (4, Mþ), 244 (100), 210 (4), 184 (6),
143 (14). HR-MS: 304.1180 (C16H17NOþ5 ; calc. 304.1185). The structure of 10n was finally established by
an X-ray crystal structure analysis (Fig. 1)3).
Dimethyl 3-Acetyl-6-methoxy-1-methylquinoline-4,4(1H)-dicarboxylate (10o). Purified by CC (neu-
tral alumina; hexane/AcOEt 70 :30). Light yellow solid. M.p. 203 – 2058. tR 15.66. IR (neat): 3094, 2938,
1
1753, 1596, 1485. H-NMR (500 MHz): 7.32 (s, 1 H); 6.99 (dd, J ¼ 2.0, 1.0, 1 H); 6.81 (s, 1 H); 6.80 (s,

Helvetica Chimica Acta – Vol. 94 (2011)
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1 H); 3.71 (s, 3 H); 3.62 (s, 6 H); 3.33 (s, 3 H); 2.24 (s, 3 H). 13C-NMR: 193.1; 170.6; 156.4; 143.6; 130.6;
122.4; 115.28; 115.26; 114.5; 109.5; 56.8; 55.9; 53.2; 40.2; 24.5. EI-MS: 333 (4, Mþ), 274 (100), 216 (3), 173
(8), 50 (1). HR-MS: 334.1293 (C17H19NOþ6 ; calc. 334.1291).
Dimethyl 3-Acetyl-1,6-dimethylquinoline-4,4(1H)-dicarboxylate (10p). Isolated by CC (SiO2;
hexane/AcOEt 80 :20). tR 13.84. IR (CH2Cl2): 2975, 2863, 1746, 1478, 1485. 1H-NMR: 7.38 – 7.10 (m,
2 H); 7.08 (s, 1 H); 6.82 – 6.80 (m, 1 H); 3.69 (s, 6 H); 3.39 (s, 3 H); 2.31 (s, 3 H); 2.20 (s, 3 H). 13C-NMR:
140.0; 136.3; 128.7; 124.9; 117.9; 112.1; 69.4; 52.4; 30.9; 26.2; 21.7. EI-MS: 317 (4, Mþ), 258 (100), 198 (4),
157 (15), 115 (3), 59 (1). HR-MS: 318.1344 (C17H19NOþ5 ; calc. 318.1341).
Dimethyl [(1Z)-1-(Dimethylamino)-3-(3-methoxyphenyl)-3-oxoprop-1-en-2-yl]propanedioate
1
(11l). Purified by CC (neutral alumina; hexane/AcOEt 85 :15). tR 14.5. H-NMR (500 MHz): 7.46 (dt,
J ¼ 8.0, 1.0, 1 H); 7.42 (t, J ¼ 2.0, 1 H); 7.31 (t, J ¼ 8.3, 1 H); 7.26 (s, 1 H); 7.06 (ddd, J ¼ 8.3, 2.9, 1.0, 1 H);
3.79 (s, 3 H); 3.75 (s, 6 H); 3.59 (s, 1 H); 2.38 (s, 6 H). 13C-NMR: 188.7; 166.7; 159.0; 141.1; 137.8; 128.6;
128.4; 120.4; 118.8; 112.0; 58.6; 54.5; 51.7; 39.8. EI-MS: Mþ not observed, 276 (100), 217 (33), 135 (14),
107 (7), 72 (14), 59 (2). HR-MS: 336.1442 (C17H21NOþ6 ; calc. 336.1447).
This work was supported by a grant from Istanbul Technical University Research Fund (project No.:
32746 and 33340).
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Received October 19, 2010