Synthesis of 5-alkylidene-2,5-dihydropyrrol-2-ones and their ring-transformation into 5,6-dihydrobenzo[h]chromones, 5,6,7,8-tetrahydrochromones and pyran-4-ones

Article abstract of DOI:10.1016/j.tet.2007.10.035

Acid-mediated ring-transformations of 5-alkylidene-2,5-dihydropyrrol-2-ones, available by cyclization of 1,3-diketone dianions with bis(imidoyl) dichlorides of oxalic acid, resulted in formation of functionalized pyran-4-ones, such as 5,6-dihydrobenzo[h]c

Full text of DOI:10.1016/j.tet.2007.10.035

Available online at www.sciencedirect.com
Tetrahedron 63 (2007) 12975–12985
Synthesis of 5-alkylidene-2,5-dihydropyrrol-2-ones and their
ring-transformation into 5,6-dihydrobenzo[h]chromones,
5,6,7,8-tetrahydrochromones and pyran-4-ones
Van T. H. Nguyen,a Joachim T. Anders,a Qingjun Ma,b
Regine Herbst-Irmerb and Peter Langera,c,
*
aInstitut fu€r Chemie, Universita€t Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
bInstitut fu€r Anorganische Chemie, Universita€t Go€ttingen, Tammannstrasse 4, 37077 Go€ttingen, Germany
cLeibniz-Institut fu€r Katalyse e. V. an der Universita€t Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
Received 21 August 2007; revised 1 October 2007; accepted 8 October 2007
Available online 11 October 2007
Abstract—Acid-mediated ring-transformations of 5-alkylidene-2,5-dihydropyrrol-2-ones, available by cyclization of 1,3-diketone dianions
with bis(imidoyl) dichlorides of oxalic acid, resulted in formation of functionalized pyran-4-ones, such as 5,6-dihydrobenzo[h]chromones and
5,6,7,8-tetrahydrochromones.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
have reported a convenient approach to functionalized
pyran-4-ones, such as 5,6-dihydrobenzo[h]chromones and
5,6,7,8-tetrahydrochromones, based on a new ring-trans
formation of 5-alkylidene-2,5-dihydropyrrol-2-ones.6 The
starting materials are available by cyclization of 1,3-
dicarbonyl dianions with bis(imidoyl) dichlorides of oxalic
acid, a reaction recently developed by us.7,8 Herein, we
wish to report full details of this methodology and studies
related to the preparative scope. In this context, the synthesis
of a variety of new 5-alkylidene-2,5-dihydropyrrol-2-ones
and pyran-4-ones is reported.
Pyran-4-ones (g-pyrones) and chromones are of pharmaco-
logical relevance and occur in a number of natural products.1
5,6-Dihydrobenzo[h]chromones and 5,6,7,8-tetrahydro-
chromones are present, for example, in artobiloxanthone,2
artonol C or in the artonins A, N and T.3 Monocyclic
pyran-4-ones are also present in nature, e.g., in 8-methyl-
10-oxopodopyrone (Scheme 1).4
O
OMe
2. Results and discussion
HO
O
OH
OH
O
The cyclization of the dianion of 2-acetyltetralone (1a) with
oxalic acid–bis(imidoyl) dichlorides 2a–e afforded the
E-configured 5-alkylidene-3-arylamino-2,5-dihydropyrrol-
2-ones 3a–e. The formation of 3a–e proceeds, as previously
reported for related reactions of b-ketoester dianions,7 by
C,O-cyclization (intermediate A) and subsequent Dimroth-
rearrangement (Schemes 2 and 3, Table 1). Treatment of a
THF solution of 3a–e with an aqueous solution of HCl
afforded the unexpected 5,6-dihydrobenzo[h]chromones
5a–e (Scheme 2). In case of 5d, the 5-alkylidene-3-hydroxy-
2,5-dihydropyrrol-2-one 4a was isolated as a side-product.
The formation of 5a–e can be explained by hydrolysis of
the enamine group, protonation (intermediate B), attack of
water (intermediate C), cleavage of the pyrrolidinone ring
(intermediate D) and, finally, acid-mediated recyclization
with extrusion of water (Scheme 2).
O
O
O
nDec
OH
artobiloxanthone
Scheme 1. Pyran-4-one natural products.
8-methyl-1'-oxopodopyrone
Pyran-4-ones have been prepared, for example, by acid-
mediated cyclization of 1,3,5-tricarbonyl compounds and
the biosynthesis also follows this pathway.5 Recently, we
* Corresponding author. Tel.: +49 381 4986410; fax: +49 381 4986412;
e-mail: peter.langer@uni-rostock.de
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.10.035

12976
V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
R2
R2
Me
O
H
O
R1
Cl
NR3
Cl
R1
O
i
O
+
H
O
R3N
O
O
O
O
O
O
O
Cyclization
O
R3N
NHR3
1a-h
2a-f
NHPh
NHPh
NHR
A
5g
5f (R = 4-(MeO)C6H4)
Dimroth-
5a
rearrangement
Scheme 3. Structures of 5a, 5f, and 5g.
R2
R2
ii
R1
R1
H+
H+
O
O
The cyclization of the dianion of 2-acetyl-1-decalone (1b)
with 2d afforded the 5-alkylidene-2,5-dihydropyrrol-2-one
3f, which was transformed into 5f (Scheme 2, Table 1).
2-Acetyl-6-methylcyclohexan-1-one (1c) was prepared by
reaction of 1-trimethylsilyloxy-6-methylcyclohex-1-ene
with acetyl chloride. The reaction of dilithiated 1c with
oxalic acid–bis(imidoyl) dichlorides 2a–d gave the 5-alkyli-
dene-2,5-dihydropyrrol-2-ones 3g–j, which were trans-
formed into the 5,6,7,8-tetrahydrochromones 5g–j.
R3
R3
N
N
O
Ring-
transformation
O
NHR3
OH
4d,k,l
3a-u
R2
R2
R1
R1
OH
OH
OH
+
H2O
+
N
R3
The cyclization of the dianions of 2-acetylcyclopentan-1-
one (1d) and 2-acetylindan-1-one (1e) with 2a afforded 3k
and 3l, respectively. Treatment of 3k and 3l with hydrochlo-
ric acid resulted only in hydrolysis of the enamine moiety
and formation of the 5-alkylidene-2,5-dihydropyrrol-2-
ones 4k and 4l, respectively. The cyclization of the dianion
of benzoylacetone (1f) with 2a gave the 5-alkylidene-2,5-di-
hydropyrrol-2-one 3m. Treatment of 3m with hydrochloric
acid afforded the carbamoylpyran-4-one 5m. The cycliza-
tion of the dianions of benzoylacetone (1f), acetylacetone
(1g) and 3-methylacetylacetone (1h) with various oxalic
acid–bis(imidoyl) dichlorides afforded the 5-alkylidene-
2,5-dihydropyrrol-2-ones 3n–u. The reaction of the latter
with an aqueous solution of hydrochloric acid resulted in
decomposition or no conversion, depending on the concen-
tration of the acid.
N
R3
O
OH
O
B
C
R2
R2
R1
OH
R1
O
O
HO
O
NHR3
O
O
NHR3
5a-j,m
D
Scheme 2. Synthesis of 5-alkylidene-2,5-dihydropyrrol-2-ones 3a–u and
4d,k,l and of pyran-4-ones 5a–j,m, i: (1) 2.2 equiv LDA, (2) 2a–f, THF,
ꢀ78/20 ꢁC; ii: HCl (1 M), THF, 1 h, 40 ꢁC.
Table 1. Products, yields, and UV–vis absorptions
a
%
1
2
3–5
R1
R2
R3
UV–visb
(3)
(4)
(5)
(3)
(5)
a
a
a
a
a
b
c
c
c
c
d
e
f
f
f
f
g
g
g
g
h
a
b
c
d
e
d
a
b
c
d
a
a
a
b
f
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
–(CH2)2(C6H4)–
–(CH2)2(C6H4)–
–(CH2)2(C6H4)–
–(CH2)2(C6H4)–
–(CH2)2(C6H4)–
–C6H10(CH2)2–
–(CH2)3CH(Me)–
–(CH2)3CH(Me)–
–(CH2)3CH(Me)–
–(CH2)3CH(Me)–
Ph
45
51
85
55
84
42
80
58
61
42
50
37
54
54
56
56
46
40
43
58
58
0
0
0
23
0
0
0
0
0
0
95
99
0
0
0
0
0
0
0
75c
95
85
63
92
77c
79c
89
75
61
0
0
30
0
0
0
431 (4.5), 255 (4.3)
427 (4.4), 353 (4.1), 255 (4.2)
433 (4.4), 272 (4.2), 249 (4.2)
447 (4.5), 260 (4.4)
436 (4.4), 314 (4.1), 219 (5.0)
405 (4.4), 256 (4.3)
399.8 (4.2), 257 (4.1)
396 (4.2), 257 (4.1)
400 (4.3), 304 (3.9), 265 (4.2)
403 (4.3), 299 (3.8), 255 (4.2)
—
—
310 (4.0), 281 (4.1), 220 (4.1)
313 (4.1), 219 (4.3), 213 (4.4)
312 (4.2), 219 (4.4), 213 (4.4)
311 (4.2), 290 (4.2), 219 (4.3)
313 (4.2), 291 (4.2), 221 (4.8)
284 (4.0), 250 (3.8)
275 (4.1), 221 (4.3)
269 (4.0), 221 (4.3)
280 (4.0), 221 (4.3)
280 (4.0), 222 (4.2)
—
—
278 (3.5)
—
—
—
—
2-MeC6H4
2-(MeO)C6H4
4-(MeO)C6H4
1-Naph
4-(MeO)C6H4
Ph
2-MeC6H4
2-(MeO)C6H4
4-(MeO)C6H4
Ph
Ph
Ph
2-MeC6H4
4-MeC6H4
4-(MeO)C6H4
Ph
2-MeC6H4
4-MeC6H4
4-(MeO)C6H4
Ph
–CH2CH2CH2–
–CH2(C6H4)–
H
H
H
H
H
H
H
H
Ph
Ph
Ph
Ph
Me
Me
Me
Me
419 (4.4), 250 (4.3)
—
—
—
—
—
—
—
—
d
a
b
f
d
a
0
0
0
0
—
—
—
—
t
u
0
0
Me
Me
0
a
b
c
Isolated yields; for the configuration of the exocyclic double bond of 3 and 4, see Section 3; no conversion was observed for 3n–u.
UV–vis (CH3CN, nm): lmax (log 3).
Structure see below (Scheme 3).

V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
12977
3.58), [D6]acetone (2.04), [D6]-dimethylsulfoxide (2.50),
and [D4]methanol (3.30) were used. Tetramethylsilane
(TMS) was used as internal standard. 13C NMR: Bruker
AM 250 (62.9 MHz), Varian VXR-200 (50.3 MHz), Varian
Mercury 200 (50.3 MHz), Varian Unity 300 (75.5 MHz),
Bruker AMX 300 (75.5 MHz), Varian Inova 500
(125.7 MHz). As solvents were used: CDCl3 (d¼77.0),
[D6]acetone (d¼29.8), [D6]DMSO (39.5), [D4]methanol
(49.0), [D8]THF (25.5, 67.7). The multiplicity of the carbon
atoms was determined by the DEPT 135 (DEPT¼
Distortionless Enhancement by Polarisation Transfer) and
APT technique (APT¼Attached Proton Test) and quoted
as CH3, CH2, CH and C for primary, secondary, tertiary
and quaternary carbon atoms. IR: Perkin Elmer 2000
FT-IR, FT-IR Bruker Vector 22, Bruker IFS 66, Nicolett 205
FT-IR. UV spectroscopy: Perkin Elmer UV/Vis/IR-Spec-
trometer Lambda 19; as solvent, CH3CN was used. Mass
spectroscopy: Finnigan MAT 95 spectrometer (electronic
ionization: EI, 70 eV), Finnigan LC-Q (electrospray ioniza-
tion, ESI). Chemical ionization with water: CI, H2O. For
preparative scale chromatography silica gel (60–200 mesh)
was used (solvents: petroleum ether (PE, bp 40–70 ꢁC) and
diethyl ether). Melting points are uncorrected and were mea-
Figure 1. Ortep plot of 5d.
The structure and the configuration of compounds 3 were
elucidated by spectroscopic methods (NOESY measure-
ments). The structure of all products was studied by spectro-
scopic methods; the structure of 5d was independently
confirmed by crystal structure analysis (Fig. 1). In the crystal
lattice of 5d, dimers are formed by hydrogen bonding
€
sured using a Buchi apparatus. Elemental analyses: Micro-
analytical laboratory of the University of Gottingen (Leco
€
CHN 2000, Heraeus Mikro U/D). Diffraction data for com-
pound 5d was collected at ꢀ173 ꢁC on a Bruker three-circle
diffractometer equipped with a SMART 6000 CCD detector.
ꢁ
˚
˚
˚
(N1–H1 0.885 A, H1/O1 2.113 A, N1–H1/O1 166.06 ,
10
˚
N1/O1 2.980 A).
Cu Ka radiation (l¼1.54178 A) was used. The structure was
solved by direct methods using SHELXS9 and refined
against F2o using SHELXL.11 All non-hydrogen atoms
were refined anisotropically, the hydrogen atom bond to
nitrogen was refined isotropically with a distance restraint,
while the riding model was used for the remaining hydrogen
atoms.
Notably, all products 5a–j and 5m exhibit strong UVabsorp-
tions (Table 1). A hypsochromic effect is generally observed
for the colourless pyran-4-ones 5a–j,m with respect to the
yellow coloured 5-alkylidene-2,5-dihydropyrrol-2-ones
3a–j,m.
In conclusion, we reported the synthesis of functionalized
pyran-4-ones, such as 5,6-dihydrobenzo[h]chromones and
5,6,7,8-tetrahydrochromones, based on acid-mediated ring-
transformations of novel 5-alkylidene-2,5-dihydropyrrol-2-
ones, which are available by cyclization of 1,3-dicarbonyl
dianions with oxalic acid–bis(imidoyl) dichlorides. The
best yields were obtained for reactions of 5-alkylidene-2,5-
dihydropyrrol-2-ones derived from cyclic 1,3-diketones.
For b-ketoester derived 5-alkylidene-2,5-dihydropyrrol-2-
ones, the reactions stopped with the simple hydrolysis of
the enamine moiety and a ring-transformation was not ob-
served. This can be explained by the lower reactivity of
the exocyclic double bond of these substrates in conjugate
addition reactions.
3.2. General procedure for the synthesis of 5-alkylidene-
3-arylamino-2,5-dihydropyrrol-2-ones (3)
ATHF solution of LDA was prepared by addition of n-BuLi
(3.05 ml, 4.4 mmol, 1.5 M solution in hexane) to a THF
solution (40 ml) of diisopropylamine (0.45 g, 0.62 ml, d¼
0.722, 4.4 mmol) at 0 ꢁC. To the LDA solution, 2.00 mmol
of the dicarbonyl compound was added at 0 ꢁC. The yellow
coloured solution was stirred at 0 ꢁC for 60 min and was
subsequently cooled to ꢀ78 ꢁC and transferred into a THF
solution (40 ml) of 2.00 mmol of oxalic acid–bis(arylimi-
doyl) dichloride at ꢀ78 ꢁC. The solution was warmed up
to 20 ꢁC overnight. To the solution, 100 ml of an aqueous
solution of ammonium chloride (1 M) was added. The or-
ganic layer was separated and the aqueous layer was
extracted with ether (4ꢂ150 ml). The combined organic
layers were dried (MgSO4), filtered and the filtrate was con-
centrated in vacuo. The residue was purified by chromato-
graphy (silica gel, pentane/ether¼10:1/1:1) to give the
3-arylamino-2,5-dihydropyrrol-2-ones 3 as yellow to red
solids.
3. Experimental section
3.1. General
All solvents were dried by standard methods and all reac-
tions were carried out under an inert atmosphere. All sol-
vents were distilled prior to use. 1H NMR: Bruker AM 250
(250 MHz), Varian VXR-200 (200 MHz), Varian Mercury
200 (200 MHz), Varian Unity 300 (300 MHz), Bruker
AMX 300 (300 MHz), Varian Inova 500 (500 MHz). For
1H NMR, the solvents CDCl3 (d¼7.26), [D8]THF (d¼1.73,
3.2.1. (5E)-5-(3,4-Dihydro-1-oxonaphthalen-2(1H)-yl-
idene)-1-phenyl-3-(phenylamino)-1H-pyrrol-2(5H)-one
(3a). Starting with a THF solution (40 ml) of LDA
(6.9 mmol, 2.3 equiv), 2-acetyltetralone (3.0 mmol, 0.57 g)
and a THF solution (40 ml) of oxalic acid–bis(phenylimidoyl)

12978
V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
chloride (3.0 mmol, 0.83 g), 3a was isolated after chromato-
graphy (n-hexane/EtOAc¼20:1) as a yellow solid (0.53 g,
2H, Ar), 7.32–7.51 (m, 4H, Ar), 7.69 (s, 1H, C4), 7.87 (s,
NH), 8.06–8.09 (dd, 1H, CH, Ar). 13C NMR (CDCl3,
62.5 MHz): d¼24.8, 28.8 (CH2), 55.9, 56.2 (CH3), 100.3
(CH), 109.0 (C), 110.6, 112.3, 116.6, 121.0, 121.5, 122.9,
123.9, 126.5, 127.1, 127.5, 128.2 (CH), 129.6 (C),132.7
(CH), 134.2, 135.3, 139.4, 143.2, 148.9, 152.4, 152.7 (C),
161.7, 187.8 (CO). MS (EI, 70 eV): m/z (%)¼454 (M++2,
4), 453 (M++1, 27), 452 (M+, 100), 423 (46), 330 (16),
302 (74), 274 (5), 141 (32), 114 (36), 77 (25). IR (KBr,
cmꢀ1): ~n¼3369ðmÞ, 3346 (m), 1701 (s), 1631 (s), 1596
(s), 1558 (s), 1536 (s), 1491 (s), 1461 (s), 1346 (s), 1297
(s), 1243 (s), 1210 (m), 1122 (s), 1027 (s), 928 (s), 738 (s).
UV–vis (CH3CN, nm): lmax (log 3)¼248.9 (4.17), 271.6
(4.21), 433.2 (4.39). Anal. Calcd for C28H24O4N2: C,
74.30; 5.35. Found: C, 73.99; H, 5.02. HRMS (EI, 70 eV):
calcd for C28H24O4N2: 452.1736; found: 452.1736ꢃ2 ppm
([M]+).
1
45%). H NMR (CDCl3, 250 MHz): d¼2.98 (t, 2H, CH2),
3.06 (t, 2H, CH2), 7.08 (d, 1H, CH, Ar), 7.1 (d, 1H, CH–
Ar), 7.13 (d, 1H, CH, Ar), 7.21 (m, 1H, CH, Ar), 7.24 (m,
1H, CH, Ar), 7.28 (m, CH, Ar), 7.36 (m, CH, Ar), 7.38
(m, 1H, CH, Ar), 7.41 (m, CH, Ar), 7.43–7.46 (m, 3H,
2CH, Ar+NH), 7.5 (CH, Ar), 7.53 (CH, Ar), 7.68 (s, 1H,
CH, C4), 8.07 (d, 1H, CH, Ar), 8.09 (d, 1H, CH–Ar). 13C
NMR (CDCl3, 62.5 MHz): d¼24.8, 28.6 (CH2), 99.9 (CH),
109.6 (C), 118.1 (2CH, Ar), 123.2 (2CH, Ar), 124.8,
126.0, 126.9, 127.3, 128.1 (CH), 129.0 (2CH, Ar), 129.3
(2CH, Ar), 129.7 (CH), 132.6, 134.9, 139.6, 139.6, 142.9,
143.7, 151.3 (C), 161.3 (CO), 187.6 (CO). IR (KBr,
cmꢀ1): ~n¼3438ðbr sÞ, 3378 (s), 3362 (s), 1689 (s), 1654
(s), 1622 (s), 1597 (s), 1558 (s), 1493 (m), 1348 (m), 1289
(m), 1239 (s), 1156 (m), 1091 (m), 931 (s), 744 (m), 691
(m), 619 (m). UV–vis (CH3CN, nm): lmax (log 3)¼255.2
(4.32), 431.2 (4.45). MS (EI, 70 eV): m/z (%)¼393
([M+1]+, 25.9), 392 (M+, 100), 375 (8), 289 (5), 272 (31),
186 (7), 141 (25), 114 (27), 90 (17), 77 (46), 51 (9).
HRMS (EI, 70 eV): calcd for C26H20O2N2: 392.1525; found:
392.1525ꢃ2 ppm ([M]+).
3.2.4. (E)-1-(4-Methoxyphenyl)-3-(4-methoxyphenyl-
amino)-5-(1-oxo-1,2,3,4-tetrahydro-2-naphthylidene)-2,5-
dihydropyrrol-2-one (3d). Starting with 2-acetyltetralone
(0.56 g, 3.0 mmol) and oxalic acid–bis[(4-methoxyphenyl)-
imidoyl]chloride (1.01 g, 3.0 mmol), 3d was isolated as a
1
yellow solid (745 mg, 55%, E/Z>98:2). H NMR (CDCl3,
3.2.2. (5E)-3-(2-Tolylamino)-5-(3,4-dihydro-1-oxonaph-
thalen-2(1H)-ylidene)-1-(2-tolyl)-1H-pyrrol-2(5H)-one
(3b). Starting with a THF solution (40 ml) of LDA
(6.9 mmol, 2.3 equiv), 2-acetyltetralone (3.0 mmol, 0.57 g)
and a THF solution (40 ml) of oxalic acid–bis(2-tolylimi-
doyl) chloride (3.0 mmol, 0.91 g), 3b was isolated after
chromatography (n-hexane/EtOAc¼20:1) as a yellow solid
250 MHz): d¼2.97 (m, 4H, CH2), 3.78, 3.81 (2ꢂs, 2ꢂ3H,
OCH3), 6.92 (t, J¼9 Hz, 4H, Ar), 7.04 (s, 1H, NH), 7.12–
7.25 (m, 5H, Ar+C-4), 7.54 (m, 3H, Ar), 8.07 (d, J¼
12 Hz, 1H, Ar). 13C NMR (CDCl3, 62.5 MHz): d¼24.6,
28.5 (CH2), 55.4, 55.5 (OCH3), 98.0 (CH, C-4), 107.7 (C),
114.1, 114.8, 119.9, 126.8, 127.1, 127.1, 128.0, 132.8
(CH, Ar), 132.3, 135.1, 136.6, 140.8, 142.8, 149.5, 155.7,
157.9, 162.1, 187.2 (C). IR (KBr, cmꢀ1): ~n¼3360ðwÞ,
2952 (w), 2936 (w), 2905 (w), 2837 (w), 1683 (m), 1653
(s), 1622 (s), 1599 (s), 1559 (s), 1532 (s), 1507 (s), 1459
(m), 1350 (s), 1299 (m), 1278 (m), 1245 (s), 1238 (s),
1170 (s), 1031 (m), 928 (s), 834 (m), 815 (m), 743 (m).
UV–vis (CH3CN, nm): lmax (log 3)¼446.9 (4.48), 259.9
(4.36). MS (EI, 70 eV): m/z (%)¼452 ([M]+, 100), 121
(69). HRMS (EI, 70 eV): calcd for C28H24N2O4: 452.1736;
found: 452.1736ꢃ2 ppm ([M]+). Anal. Calcd for
C28H24N2O4: C, 74.32; H, 5.35. Found: C, 74.49; H, 5.49.
1
(0.640 g, 51%). H NMR (CDCl3, 250 MHz): d¼2.32 (s,
3H, CH3), 2.33 (s, 3H, CH3), 2.89 (t, 2H, CH2), 2.94 (t,
2H, CH2), 6.95–6.99 (m, Ar), 7.05–7.1 (m, Ar), 7.16 (s, 1H,
C4), 7.21–7.44 (m, Ar, NH), 7.86 (d, 1H, Ar), 7.89 (d, 1H,
Ar), 7.90–8.04 (m, Ar). 13C NMR (CDCl3, 62.5 MHz):
d¼17.6, 18.6 (CH3), 99.8, 109.19, 109.4, 117.9, 122.8,
123.6, 125.9, 126.6, 127.1, 128.3, 130.9, 131.4, 132.1,
135.2, 138.1 (CH), 140.0, 141.0, 143.2, 151.1, 161.7,
177.2 (C), 187.8, 194.0 (CO). IR (KBr, cmꢀ1): ~n¼
3374ðmÞ, 3289 (w), 2950 (w), 1699 (m), 1661 (m), 1633
(s), 1599 (s), 1563 (s), 1545 (s), 1459 (m), 1348 (m), 1292
(m), 1242 (s), 1157 (m), 1081 (m), 928 (m), 738 (m). UV–
vis (CH3CN, nm): lmax (log 3)¼255.5 (3.18), 299.8 (3.96),
352.8 (4.11), 426.7 (4.35). MS (EI, 70 eV): m/z (%)¼423
(M++1, 25), 422 (M+, 94), 392 (17), 315 (20), 286 (69),
275 (20), 247 (19), 141 (34), 114 (42), 105 (66), 91 (100),
66 (34), 28 (40). HRMS (EI, 70 eV): calcd for
C28H24O2N2: 420.1838; found: 420.1838ꢃ2 ppm ([M]+).
Anal. Calcd for C28H24O2N2: C, 79.98; H, 5.80. Found: C,
79.99; H, 6.01.
3.2.5. (5E)-5-(3,4-Dihydro-1-oxonaphth-2(1H)-ylidene)-
1-(naphth-1-yl)-3-(naphth-1-ylamino)-1H-pyrrol-2(5H)-
one (3e). Starting with a THF solution (40 ml) of LDA
(6.9 mmol, 2.3 equiv), 2-acetyltetralone (3.0 mmol, 0.57 g)
and a THF solution (40 ml) of oxalic acid–bis(naphth-1-yl-
imidoyl) chloride (3.0 mmol, 1.13 g), 3e was isolated after
chromatography (n-hexane/EtOAc¼20:1) as a yellow solid
(1.20 g, 84%). 1H NMR (CDCl3, 250 MHz): d¼2.94 (t,
2H, CH2), 3.02 (t, 2H, CH2), 7.25 (s, 1H, CH, C4), 7.31–
7.34 (m, Ar), 7.42 (m, Ar), 7.51–7.6 (m, Ar), 7.69–7.72
(m, Ar), 7.76–7.81 (m, Ar), 7.88–7.95 (m, Ar), 8.0–8.13
(m, Ar), 8.24–8.26 (m, Ar), 8.45–8.48 (m, Ar). 13C NMR
(CDCl3, 250 MHz): d¼24.9, 28.8 (CH2), 100.9, 109.9,
115.8, 119.0, 120.4, 122.1, 124.0, 126.2, 126.4, 126.5,
126.5, 127.5, 128.3, 129.2, 131.1, 135.0, 135.1 (CH), 140.3,
140.9, 143.2, 152.4 (C), 161.4, 187.7 (CO). MS (EI,
70 eV): m/z (%)¼492 (M+, 9), 491 (36), 322 (26), 204 (7),
167 (10), 148 (23), 143 (36), 114 (18), 90 (7), 32 (17), 28
(100). IR (KBr, cmꢀ1): ~n¼3436ðbr sÞ, 3392 (s), 1679 (m),
1654 (m), 1616 (s), 1599 (s), 1497 (m), 1400 (m), 1345
(m), 1243 (s), 1156 (m), 925 (m), 704 (m), 679 (m), 616
3.2.3. (5E)-3-(2-Methoxyphenylamino)-5-(3,4-dihydro-1-
oxonaphthalen-2-(1H)-ylidene)-1-(2-methoxyphenyl)-
1H-pyrrol-2(5H)-one (3c). Starting with a THF solution
(40 ml) of LDA (6.9 mmol, 2.3 equiv), 2-acetyltetralone
(3.0 mmol, 0.57 g) and a THF solution (40 ml) of oxalic
acid–bis(2-methoxyphenyl)imidoyl chloride (3.0 mmol,
1.01 g), 3c was isolated after chromatography (n-hexane/
1
EtOAc¼25:1/20:1) as a yellow solid (1.15 g, 85%). H
NMR (CDCl3, 250 MHz): d¼2.89 (m, 2H, CH2), 2.96 (m,
2H, CH2), 3.90 (s, 3H, OCH3), 3.94 (s, 3H, CH3), 6.91–
6.94 (m, 1H, Ar), 6.99–7.05 (m, 2H, Ar), 7.17–7.26 (m,

V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
12979
(w). UV–vis (CH3CN, nm): lmax (log 3)¼219.1 (4.96), 277.7
(4.11), 314.0 (4.13), 435.6 (4.44). HRMS (EI, 70 eV): calcd
for C34H24O2N2: 492.1838; found: 492.1838ꢃ2 ppm
([M]+).
1.39–1.42 (m, 2H, CH2), 1.51–1.62 (m, 2H, CH2), 1.81–
1.87 (m, 2H, CH2), 2.13 (s, 6H, 2CH3), 2.30–2.47 (m, 1H,
CHCH3), 6.99 (s, 1H, CH, C4), 7.01–7.03 (m, Ar), 7.09–
7.14 (m, Ar), 7.14–7.29 (m, Ar, NH), 7.40–7.47 (m, Ar).
13C NMR (CDCl3, 62.5 MHz): d¼16.8, 17.6, 18.6 (CH3),
22.1, 26.2, 31.7, 35.6 (CH2), 44.5, 99.8 (CH), 110.2 (C),
117.6, 122.8, 123.4, 125.8, 126.5 (CH), 127.1, 127.7 (C),
130.7, 131.1 (CH), 133.5, 138.2, 142.6, 151.2 (C), 160.6,
203.6 (CO). MS (EI, 70 eV): m/z (%)¼388.5 (M++2, 4),
387.5 (M++1, 28), 386 (M+, 100), 343 (12), 280 (18), 252
(55), 224 (10), 158 (5), 130 (14), 118 (14), 91 (30), 66
(10). IR (KBr, cmꢀ1): ~n¼3365ðwÞ, 2931 (s), 2846 (m),
1685 (s), 1625 (s), 1597 (s), 1574 (s), 1536 (s), 1495 (s),
1350 (m), 1292 (m), 1229 (m), 1187 (m), 1156 (w), 1082
(m), 964 (m), 928 (m), 760 (m). UV–vis (CH3CN, nm):
lmax (log 3)¼257.2 (4.09), 395.55 (4.22). HRMS (EI,
70 eV): calcd for C25H26O2N2: 386.1994; found:
386.1994ꢃ2 ppm ([M]+).
3.2.6. (E)-1-(4-Methoxyphenyl)-3-(4-methoxyphenyl-
amino)-5-(1-oxo-1,2,3,4,4a,5,6,7,8,8a-decahydro-2-naph-
thylidene)-2,5-dihydropyrrol-2-one (3f). Starting with
2-acetyldecalone (0.58 g, 3.0 mmol) and oxalic acid–bis[(4-
methoxyphenyl)imidoyl]chloride (1.01 g, 3.0 mmol), 3f
was isolated as a yellow solid (578 mg, 42%, E/Z>98:2).
1H NMR (CDCl3, 250 MHz): d¼1.05–1.55 (m, 11H, CH,
CH2), 2.31, 2.81, 3.02 (3ꢂm, 3ꢂ1H, CH, CH2), 3.82, 3.85
(2ꢂs, 2ꢂ3H, OCH3), 6.89 (m, 4H, Ar), 7.19 (m, 3H, Ar),
7.24 (s, 1H, C-4), 7.54 (m, 2H, Ar). 13C NMR (CDCl3,
62.5 MHz): d¼24.8, 25.8, 26.2, 26.5, 30.4, 34.3 (CH2),
39.4, 54.4 (CH), 55.3, 55.4 (OCH3), 97.9 (CH, C-4), 108.0
(C), 114.0, 114.7, 119.6, 127.2 (CH, Ar), 132.9, 136.7,
140.0, 149.6, 155.4, 157.8, 161.1, 201.31 (C). IR (KBr,
cmꢀ1): ~n¼3352ðwÞ, 3293 (w), 3041 (w), 2923 (s), 2851
(m), 1684 (s), 1658 (m), 1621 (s), 1555 (s), 1535 (s), 1507
(s), 1463 (m), 1443 (m), 1349 (m), 1295 (m), 1247 (s),
1170 (m), 1076 (m), 1035 (m), 924 (w), 836 (m), 820 (m).
UV–vis (CH3CN, nm): lmax (log 3)¼404.8 (4.40), 256.0
(4.28). MS (EI, 70 eV): m/z (%)¼458 ([M]+, 100). HRMS
(EI, 70 eV): calcd for C28H30N2O4: 458.2205; found:
458.2205ꢃ2 ppm ([M]+). Anal. Calcd for C28H30N2O4: C,
73.34; H, 6.59. Found: C, 73.16; H, 6.72.
3.2.9. (5E)-3-(2-Methoxyphenylamino)-1-(2-methoxy-
phenyl)-5-(3-methyl-2-oxocyclohexylidene)-1H-pyrrol-
2(5H)-one (3i). Starting with a THF solution (40 ml) of LDA
(6.9 mmol, 2.3 equiv), 2-acetyl-6-methylcyclohexanone
(3.0 mmol, 0.433 g) and a THF solution (40 ml) of oxalic
acid–bis(2-methoxyphenyl)imidoyl chloride (3.0 mmol,
1.01 g), 3i was isolated after chromatography (n-hexane/
1
EtOAc¼20:1) as a yellow solid (0.768 g, 61%). H NMR:
d¼1.18 (d, 3H, CH3), 1.61–1.70 (m, 1H, CH2), 1.81–1.89
(m, 1H, CH2), 1.98–2.05 (m, 2H, CH2), 2.35–2.42 (m, 1H,
CH2), 2.51–2.61 (m, 1H, CH2), 2.78–2.85 (m, 1H,
CHCH3), 3.89 (s, 3H, OCH3), 3.92 (s, 3H, CH3), 6.96 (s,
1H, C4), 6.99–7.02 (m, Ar), 7.14 (d, 1H, Ar), 7.16 (d, 1H,
Ar), 7.19 (d, 1H, Ar), 7.33 (s, 1H, NH) 4.35 (d, 1H, Ar),
7.39–7.43 (m, Ar). 13C NMR (CDCl3, 62.5 MHz): d¼16.8
(CH3), 22.1, 26.0, 31.7 (CH2), 44.4 (CH), 55.9, 56.2
(CH3), 100.3 (CH), 109.8 (C), 110.5, 112.2, 116.4, 120.9,
121.4, 122.7, 123.9, 126.4 (CH), 129.7, 134.2, 138.7,
148.8, 152.6, 152.7 (C), 160.6, 203.6 (CO). MS (EI,
70 eV): m/z (%)¼422.6 (M++2, 4), 421 (M++1, 29), 420
(100), 387 (51), 375 (13), 296 (9), 268 (38), 134 (9), 77
(11), 66 (5). IR (KBr, cmꢀ1): ~n¼3376ðsÞ, 2932 (m), 1702
(s), 1630 (s), 1557 (s), 1532 (s), 1462 (s), 1348 (m), 1294
(m), 1247 (s), 1182 (m), 1129 (m), 1026 (m), 924 (m), 751
(m). UV–vis (CH3CN, nm): lmax (log 3)¼264.8 (4.18),
303.9 (3.91), 400.2 (4.32). HRMS (EI, 70 eV): calcd for
C25H26O4N2: 418.1893; found: 418.1893ꢃ2 ppm ([M]+).
Anal. Calcd for C25H26O4N2: C, 71.70; H, 6.26. Found: C,
70.70; H, 6.47.
3.2.7. (5E)-5-(3-Methyl-2-oxocyclohexylidene)-1-phenyl-
3-(phenylamino)-1H-pyrrol-2(5H)-one (3g). Starting
with a THF solution (40 ml) of LDA (6.9 mmol, 2.3 equiv),
2-acetyl 6-methylcyclohexanone (3.0 mmol, 0.433 g) and
a THF solution (40 ml) of oxalic acid–bis(phenylimidoyl)
chloride (3.0 mmol, 0.83 g), 3g was isolated after chromato-
graphy (n-hexane/EtOAc¼20:1) as a yellow solid (0.743 g,
1
80%). H NMR (CDCl3, 250 MHz): d¼1.19 (d, 3H, CH3),
1.21–1.32 (m, 2H, CH2), 1.53–1.62 (m, 2H, CH2), 1.85–
1.89 (m, 2H, CH2), 2.37–2.42 (m, 1H, CHCH3), 7.05–7.10
(m, 2H, Ar), 7.19–7.2 (m, Ar), 7.12 (s, 1H, C4), 7.12–7.22
(m, Ar), 7.35–7.50 (m, Ar). 13C NMR (CDCl3, 62.5 MHz):
d¼16.8 (CH3), 22.1 (CH2), 26.3 (CH2), 31.7 (CH2), 44.5
(CH), 100.2 (CH), 110.2 (C), 118.2 (CH, Ph), 123.2 (CH),
125.2 (CH, Ph), 126.2 (CH), 129.2, 129.8 (CH, Ph), 139.2,
139.9, 144.0, 151.7 (C), 160.5 (CO), 203.6 (CO). MS (EI,
70 eV): m/z (%)¼359 (M++1, 26), 358 (M+, 100), 315
(18), 238 (35), 210 (14), 154 (7), 77 (31), 55 (6), 29 (6).
IR (KBr, cmꢀ1): ~n¼3360ðwÞ, 2973 (m), 2932 (m), 2862
(m), 2361 (w), 1688 (s), 1623 (s), 1596 (s), 1561 (s), 1495
(m), 1447 (m), 1349 (m), 1288 (m), 1228 (m), 1154 (m),
1116 (m), 1091 (m), 927 (m), 750 (m), 690 (m). UV–vis
(CH3CN, nm): lmax (log 3)¼257.2 (4.09), 399.84 (4.17).
HRMS (EI, 70 eV): calcd for C24H22O2N2: 367.1208; found:
367.1208ꢃ2 ppm ([M]+).
3.2.10. (E)-1-(4-Methoxyphenyl)-3-(4-methoxyphenyl-
amino)-5-(6-methyl-2-oxo-cyclohex-1-ylidene)-2,5-
dihydropyrrol-2-one (3j). Starting with 2-acetyl-6-methyl-
cyclohexanone (463 mg, 3.0 mmol) and oxalic acid–bis[(4-
methoxyphenyl)imidoyl]chloride (1.01 g, 3.0 mmol), 3j was
isolated as a yellow solid (527 mg, 42%). 1H NMR (CDCl3,
3
3.2.8. (5E)-5-(3-Methyl-2-oxocyclohexylidene)-1-phenyl-
3-(phenylamino)-1H-pyrrol-2(5H)-one (3h). Starting
with a THF solution (40 ml) of LDA (6.9 mmol, 2.3 equiv),
2-acetyl-6-methylcyclohexanone (3.0 mmol, 0.433 g) and
a THF solution (40 ml) of oxalic acid–bis(2-tolylimidoyl)
chloride (3.0 mmol, 0.91 g), 3h was isolated after chromato-
graphy (n-hexane/EtOAc¼20:1) as a yellow solid (0.676 g,
250 MHz): d¼1.19 (d, J¼6.8 Hz, 3H, CHCH3), 1.42–1.60
(m, 1H, CH2), 1.62–1.80 (m, 1H, CH2), 1.82–2.00 (m, 2H,
CH2), 2.30–2.50 (m, 1H, CH2), 2.58–2.78 (m, 1H, CH2),
2.83–3.05 (m, 1H, CHCH3), 3.81 (s, 3H, OCH3), 3.84 (s,
3H, OCH3), 6.89–6.97 (m, 5H, Ar+NH), 7.17 (d, J¼7.9 Hz,
2H, Ar), 7.25 (s, 1H, CH, C-4), 7.53 (d, J¼8.8 Hz, 2H, Ar).
13C NMR (CDCl3, 75.5 MHz): d¼16.70 (CH3), 21.88,
25.99, 31.41 (CH2), 44.06 (CH), 55.42, 55.55 (OCH3),
1
58%). H NMR (CDCl3, 250 MHz): d¼1.19 (d, 3H, CH3),

12980
V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
98.05 (CH, C-4), 108.54 (C), 114.14, 114.79, 119.91, 126.95
(CH, PMP), 132.97, 136.70, 140.40, 149.90, 155.64, 157.86
(C), 161.11 (NCO), 203.25 (CO). IR (KBr, cmꢀ1):
~n¼3372ðmÞ, 3296 (m), 2932 (m), 2837 (w), 1682 (s), 1658
(s), 1619 (s), 1529 (s), 1508 (s), 1460 (m), 1443 (m), 1350
(m), 1323 (w), 1296 (s), 1247 (s), 1176 (s), 1113 (w), 1081
(m), 1033 (s), 963 (w), 924 (m), 836 (m). UV–vis (CH3CN,
nm): lmax (log 3)¼402.6 (4.33), 299.2 (3.85), 255.2 (4.21).
MS (EI, 70 eV): m/z (%)¼418 ([M]+, 100), 375 (8), 296
(6), 268 (10), 134 (8). HRMS (EI, 70 eV): calcd for
C25H26N2O4: 418.1893; found: 418.1893ꢃ2 ppm ([M]+).
1559 (s), 1531 (s), 1494 (s), 1446 (s), 1402 (m), 1285 (m),
1249 (s), 1178 (m), 1086 (m), 1044 (m), 940 (m), 773 (m),
754 (m), 691 (m). UV–vis (CH3CN, nm): lmax (log 3)¼
419.0 (4.44), 250.0 (4.29). MS (EI, 70 eV): m/z (%)¼366
([M]+, 100), 261 (35), 105 (69). HRMS (EI, 70 eV): calcd
for C24H18N2O2: 366.1368; found: 366.1368ꢃ2 ppm
([M]+). Anal. Calcd for C24H18N2O2: C, 78.67; H, 4.95.
Found: C, 77.81; H, 5.34.
3.2.14. (E)-5-(2-Oxo-2-phenylethylidene)-1-(2-tolyl)-3-
(2-tolylamino)-2,5-dihydropyrrol-2-one (3n). Starting with
benzoylacetone (162 mg, 1.00 mmol) and oxalic acid–bis-
(2-tolylimidoyl) chloride (305 mg, 1.00 mmol), 3n was isolated
as a yellow solid (212 mg, 54%, E/Z¼1:1). 1H NMR
(CDCl3, 250 MHz) E-isomer: d¼2.38 (s, 3H, Me), 2.39 (s,
3H, Me), 6.66 (s, 1H, CH–CO), 7.08 (dd, J¼7.9, 7.4 Hz,
1H, Ar), 7.24–7.36 (m, 6H, Ar, C-4, NH), 7.42–7.56 (m,
5H, Ar), 7.95 (d, J¼7.3 Hz, 2H, Ar). 13C NMR (CDCl3,
50.3 MHz) E-isomer: d¼17.4 (ArCH3), 18.3 (ArCH3), 96.3
(CH–CO), 98.0 (CH, C-4), 118.2, 121.2, 122.4, 124.0,
125.9, 126.4, 127.0, 127.7 (CH), 128.4 (C), 128.5, 130.6,
131.0 (CH), 132.7, 134.3, 137.3, 139.4, 141.3, 142.3 (C),
167.72 (NCO), 189.76 (CO). IR (KBr, cmꢀ1): ~n¼3366ðmÞ,
3287 (m), 3056 (w), 2923 (w), 2852 (w), 1692 (m), 1665
(s), 1629 (s), 1596 (s), 1580 (s), 1562 (s), 1537 (s), 1525 (s),
1485 (m), 1458 (m), 1264 (m), 1252 (m), 1114 (w), 1042
(m), 938 (w), 737 (s), 703 (m). UV–vis (CH3CN, nm): lmax
(log 3)¼412.5 (4.19), 245.5 (4.21). MS (EI, 70 eV): m/z
(%)¼394 ([M]+, 100), 289 (60), 275 (60), 261 (8), 105 (20).
3.2.11. (E)-5-(2-Oxocyclopent-1-ylidene)-1-phenyl-3-
phenylamino-2,5-dihydropyrrol-2-one (3k). Starting with
2-acetylcyclopentanone (0.47 ml, 4.0 mmol) and oxalic acid–
bis(phenylimidoyl) chloride (1.11 g, 4.0 mmol), 3k was iso-
lated as a yellow solid (660 mg, 50%, E/Z>98:2). 1H NMR
(CDCl3, 250 MHz): d¼1.49 (quint, J¼8 Hz, 2H, CH2),
2.14, 2.60 (2ꢂt, J¼8 Hz, 2ꢂ2H, CH2), 6.89 (m, 2H, Ph),
6.95–7.14 (m, 5H, Ph, C-4), 7.35 (t, J¼7 Hz, 2H, Ph), 7.65
(d, J¼7 Hz, 2H, Ph), 7.72 (s, 1H, NH). 13C NMR (CDCl3,
62.5 MHz): d¼18.40, 25.42, 38.44 (CH2), 95.42 (CH,
C-4), 107.43 (C), 117.33, 118.83, 122.65, 127.09, 127.28,
127.68 (CH, Ar), 138.17, 138.64, 142.35, 149.97, 156.73,
204.70 (C). IR (KBr, cmꢀ1): ~n¼3332ðmÞ, 3059 (w), 2967
(w), 2950 (w), 1701 (s), 1679 (s), 1631 (s), 1595 (s), 1579
(s), 1536 (s), 1488 (m), 1444 (m), 1325 (m), 1292 (m),
1281 (m), 1222 (m), 1212 (m), 1195 (m), 1089 (m), 974
(m), 776 (m), 752 (m). UV–vis (CH3CN, nm): lmax
(log 3)¼406.0 (4.26), 382.0 (4.20), 256.5 (4.20). MS (EI,
70 eV): m/z (%)¼330 ([M]+, 100), 240 (51). HRMS (EI,
70 eV): calcd for C21H18N2O2: 330.1368; found:
330.1368ꢃ2 ppm ([M]+).
3.2.15. (E)-5-(2-Oxo-2-phenylethylidene)-1-(4-tolyl)-3-
(4-tolylamino)-2,5-dihydropyrrol-2-one (3o). Starting with
benzoylacetone (162 mg, 1.00 mmol) and oxalic acid–bis(4-
tolylimidoyl) chloride (305 mg, 1.00 mmol), 3o was isolated
as a yellow solid (223 mg, 56%, E-isomer: 130 mg, 32%,
E/Z¼10:1; Z-isomer: 93 mg, 24%, E/Z¼1:10). 1H NMR
(CDCl3, 300 MHz) E-isomer: d¼2.25 (s, 3H, Me), 2.28 (s,
3H, Me), 6.53 (s, 1H, CH–CO), 7.08 (s, 1H, C-4), 7.14–
7.29 (m, 6H, Ar, NH), 7.35–7.46 (m, 6H, Ar), 7.87 (dd,
J¼7.6, 1.5 Hz, 2H, Ar); Z-isomer: d¼2.34 (s, 3H, Me), 2.44
(s, 3H, Me), 6.33 (s, 1H, CH–CO), 7.11 (s, 1H, C-4), 7.13–
7.24 (m, 6H, Ar, NH), 7.32–7.51 (m, 6H, Ar), 7.79 (dd,
J¼8.3, 1.5 Hz, 2H, Ar). 13C NMR (CDCl3, 50.3 MHz) E-iso-
mer: d¼20.79 (ArCH3), 21.12 (ArCH3), 95.62 (CH–CO),
97.62 (CH, C-4), 118.52, 124.79, 127.61, 128.43, 129.58,
130.12, 132.10 (CH), 133.44, 136.27, 136.53, 139.54,
140.78, 141.59, 150.46 (C), 167.88 (NCO), 189.66 (CO);
Z-isomer: d¼20.83 (ArCH3), 21.27 (ArCH3), 95.53 (CH–
CO), 100.35 (CH, C-4), 118.24, 127.74, 128.02, 128.46,
130.14, 130.29 (CH), 130.56 (C), 132.25 (CH), 133.08,
136.81, 138.38, 139.66, 154.89, 154.95 (C), 166.68 (NCO),
190.01 (CO). IR (KBr, cmꢀ1): ~n¼3356ðwÞ, 3304 (w), 3056
(w), 2922 (m), 2855 (w), 1689 (m), 1650 (s), 1627 (s), 1614
(s), 1597 (s), 1579 (s), 1556 (s), 1530 (s), 1447 (m), 1404
(m), 1309 (m), 1285 (m), 1247 (s), 1168 (m), 1046 (m), 940
(m), 808 (m), 774 (m), 697 (m), 651 (m). UV–vis (CH3CN,
nm): lmax (log 3)¼426.0 (4.27), 252.5 (4.24). MS (EI,
70 eV): m/z (%)¼394 ([M]+, 80), 289 (100), 261 (16), 172
(8), 105 (20). HRMS (EI, 70 eV): calcd for C26H22N2O2:
394.1681; found: 394.1681ꢃ2 ppm ([M]+).
3.2.12. (E)-5-(1-Oxo-indan-2-ylidene)-1-phenyl-3-phenyl-
amino-2,5-dihydropyrrol-2-one (3l). Starting with 2-acetyl-
indan-1-one (0.35 g, 2.0 mmol) and oxalic acid–bis(phenyl-
imidoyl) chloride (554 mg, 2.0 mmol), 3l was isolated as
a yellow solid (280 mg, 37%, E/Z>98:2). 1H NMR (CDCl3,
250 MHz): d¼3.84 (s, 2H, CH2), 7.08 (t, 1H, Ar), 7.22 (m,
4H, Ar), 7.30–7.60 (m, 10H, CH, Ar, NH), 7.80 (d, J¼9 Hz,
1H, Ar). 13C NMR (CDCl3, 62.5 MHz): d¼30.1 (CH2),
97.8 (CH, C-4), 109.4 (C), 118.1, 123.2, 123.3, 125.1,
125.9, 126.3, 127.2, 129.0, 129.7, 133.5 (CH, Ar), 138.9,
139.3, 140.5, 143.4, 147.7, 151.2, 160.0, 193.3 (C). MS (EI,
70 eV): m/z (%)¼378 ([M]+, 100), 349 (10), 258 (40).
HRMS (EI, 70 eV): calcd for C25H18N2O3: 378.1368; found:
378.1368ꢃ2 ppm ([M]+). Anal. Calcd for C25H18N2O2: C,
79.35; H, 4.79. Found: C, 78.91; H, 5.04.
3.2.13. (E)-5-(2-Oxo-2-phenylethylidene)-1-phenyl-3-
phenylamino-2,5-dihydropyrrol-2-one (3m). Starting with
benzoylacetone (486 mg, 3.0 mmol) and oxalic acid–bis(phe-
nylimidoyl) chloride (831 mg, 3.0 mmol), 3m was isolated as
a yellow solid (592 mg, 54%, E/Z¼10:1). 1H NMR (CDCl3,
250 MHz): d¼6.65 (s, 1H, CH–CO), 7.11 (t, J¼9 Hz, 1H,
Ar), 7.20–7.55 (m, 14H, Ar, C-4, NH), 7.97 (d, J¼9 Hz,
2H, Ph). 13C NMR (CDCl3, 62.5 MHz): d¼96.21 (CH–
CO), 98.47 (CH, C-4), 118.46, 123.74, 124.81, 126.37,
127.76, 128.55, 129.05, 129.69, 132.32 (CH, Ph), 139.08,
139.42, 141.10, 142.85, 151.05, 167.61, 189.61 (C). IR
(KBr, cmꢀ1): ~n¼3356ðmÞ, 3306 (m), 3060 (w), 2919 (s),
2851 (m), 1694 (s), 1651 (s), 1625 (s), 1595 (s), 1582 (s),
3.2.16. (E)-5-(2-Oxopropylidene)-1-aryl-3-arylamino-
2,5-dihydropyrrol-2-one (3p). Starting with a THF solution

V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
12981
(40 ml) of LDA (6.9 mmol, 2.3 equiv), benzoylacetone
(3.0 mmol, 0.49 g) and a THF solution (40 ml) of oxalic
acid–bis(4-methoxyphenyl)imidoyl chloride (3.0 mmol,
1.01 g), 3p was isolated after chromatography (n-hexane/
EtOAc¼20:1) as a yellow solid (0.72 g, 56%). H NMR
Tol), 127.66 (C), 130.60, 131.21 (CH, Tol), 133.15,
137.55, 138.36, 141.95, 150.03 (C), 162.07 (C, NCO),
195.92 (C, COCH3). MS (EI, 70 eV): m/z (%)¼333
([M+H]+, 22), 332 ([M]+, 100), 317 (16), 289 (44), 275
(16), 247 (12), 233 (8), 198 (12), 174 (8), 156 (8), 130
(10), 107 (12).
1
(CDCl3, 250 MHz): d¼3.84 (s, 3H, CH3O), 3.86 (s, 3H,
CH3O), 6.65 (s, 1H, CHCO), 6.94 (d, 2H, CH,Ar), 6.97 (d,
2H, 2CH, Ar), 7.17 (s, 1H, NH), 7.24–7.27 (m, CH, Ar),
7.38 (s, 1H, CH, C4), 7.54 (d, 2H, 2CH, Ar), 7.58 (d, 2H,
2CH, Ar), 7.97 (d, 2H, 2CH, Ar), 7.99 (d, 2H, 2CH, Ar).
13C NMR (CDCl3, 62.5 MHz): d¼55.5 (CH3O), 55.6
(CH3O), 95.2 (CHCO), 96.7 (CH, C4), 114.3 (2CH, Ar),
114.9 (2CH, Ar), 120.5 (2CH, Ar), 126.9 (2CH, Ar), 132.1
(CH, Ar), 132.3 (C), 136.4 (C–NH), 139.7 (C–CO), 142.6
(C4-NH), 149.5 (C–OCH3), 156.3 (C–OCH3), 158.3
(]CN), 168.2 (CO), 189.8 (CO). IR (KBr, cmꢀ1):
~n¼3432ðbr sÞ, 1645 (s), 1625 (s), 1555 (s), 1509 (s), 1246
(s), 1170 (m), 1032 (m), 942 (m), 836 (m). UV–vis
(CH3CN, nm): lmax (log 3)¼255.4 (5.31), 431.2 (5.41).
MS (EI, 70 eV): m/z (%)¼429 (M++1, 26), 428 (M+, 100),
349 (3), 321 (44), 276 (10), 265 (5), 171 (6), 122 (14).
HRMS (EI, 70 eV): calcd for C26H22O4N2: 426.1580; found:
426.1580ꢃ2 ppm ([M]+).
3.2.19. (E)-5-(2-Oxopropylidene)-1-(4-tolyl)-3-(4-tolyl-
amino)-2,5-dihydropyrrol-2-one (3s). Starting with acetyl-
acetone (600 mg, 0.62 ml, 6.0 mmol) and oxalic acid–bis-
(p-tolylimidoyl) chloride (1.83 g, 6.0 mmol), 3s was isolated
as a yellow solid (856 mg, 43%, E/Z>98:2). 1H NMR
(CDCl3, 200 MHz): d¼2.22, 2.30, 2.33 (s, 9H, COCH3,
Tol–CH3), 5.87 (s, 1H, CHCOCH3), 7.00–7.50 (m, 9H, 4-
H, Tol). 13C NMR (CDCl3, 50.3 MHz): d¼20.79, 21.12
(Tol–CH3), 31.64 (COCH3), 97.17 (CH, CHCOCH3),
98.90 (CH, C-4), 118.40, 124.71, 129.51, 130.06 (CH,
Tol), 133.25, 136.51, 136.56 (C, C-3, Tol–C to CH3),
140.73, 141.02 (C, Tol–C to N), 150.54 (C, C-5), 165.83
(C, NCO), 197.20 (C, COCH3). IR (KBr, cmꢀ1): ~n¼
3225ðwÞ, 3028 (w), 1700 (m), 1664 (s), 1630 (s), 1560 (s),
1523 (s), 1415 (m), 1235 (m), 1078 (m), 960 (m). MS
(CI, H2O): m/z (%)¼333 ([M+H]+). Anal. Calcd for
C21H20N2O2: C, 75.88; H, 6.07; N, 8.42. Found: C, 75.68;
H, 6.27; N, 8.58.
3.2.17. (E)-5-(2-Oxopropylidene)-1-phenyl-3-phenyl-
amino-2,5-dihydropyrrol-2-one (3q). Starting with acetyl-
acetone (600 mg, 0.62 ml, 6.0 mmol) and oxalic acid–
bis(phenylimidoyl) chloride (1.66 g, 6.0 mmol), 3q was
3.2.20. (5E)-3-(4-Methoxyphenylamino)-1-(4-methoxy-
phenyl)-5-(2-oxopropylidene)-1H-pyrrol-2(5H)-one (3t).
Starting with a THF solution (40 ml) of LDA (6.9 mmol,
2.3 equiv), acetylacetone (3.0 mmol, 0.30 g) and a THF so-
lution (40 ml) of oxalic acid–bis(4-methoxyphenyl)imidoyl
chloride (3.0 mmol, 1.01 g), 3t was isolated after chromato-
graphy (n-hexane/EtOAc¼20:1) as a yellow solid (0.637 g,
58%). 1H NMR (CDCl3, 250 MHz): d¼2.24 (s, 3H,
CH3CO), 3.833 (s, 3H, CH3O), 3.85 (s, 3H, CH3O), 5.89
(s, 1H, CHCO), 6.91 (d, 2H, 2CH, Ar), 6.94 (d, 2H, 2CH,
Ar), 7.14 (s, 1H, NH), 7.19 (d, 2H, 2CH, Ar), 7.22 (d, 2H,
2CH, Ar), 7.49 (s, 1H, CH, C4), 7.52 (s, 1H, CHCO). 13C
NMR (CDCl3, 62.5 MHz): d¼35.5, 55.7, 55.8 (CH3), 96.5,
98.8, 114.4 (CH), 114.5 (2CH, Ar), 115.2 (2CH, Ar),
115.9 116.8, 117.6, 118.6 (C), 120.7 (2CH, Ar), 127.0
(2CH, Ar), 158.4, 167.8 (CO). IR (KBr, cmꢀ1):
~n¼3434ðbr sÞ, 3322 (m), 3044 (w), 3000 (w), 1694 (m),
1661 (m), 1628 (s), 1597 (s), 1531 (s), 1507 (s), 1462 (m),
1358 (m), 1294 (m), 1247 (s), 1229 (m), 1175 (s), 1075
(s), 1033 (m), 955 (m), 833 (m), 567 (m). UV–vis
(CH3CN, nm): lmax (log 3)¼255.3 (4.29), 297.4 (3.89),
394.0 (4.36). MS (EI, 70 eV): m/z (%)¼365 (M++1, 25),
364 (100), 349 (34), 321 (46), 307 (7), 214 (17), 188 (17),
172 (30), 122 (12.56), 77 (12), 43 (34), 28.0 (3). HRMS
(EI, 70 eV): calcd for C21H20O2N2: 364.1423; found:
364.1423ꢃ2 ppm ([M]+).
1
isolated as a yellow solid (840 mg, 46%, E/Z>98:2). H
NMR (CDCl3, 200 MHz): d¼2.25 (s, 3H, COCH3), 5.90
(s, 1H, CHCOCH3), 7.00–7.60 (m, 11H, 4-H, Ph). 13C
NMR (CDCl3, 50.3 MHz): d¼31.75 (COCH3), 98.06 (CH,
CHCOCH3), 99.54 (CH, C-4), 118.39, 123.65, 124.53,
126.20, 128.96, 129.67 (CH, Ph), 139.13, 140.59, 143.44
(C, C-3, Ph–C to N), 151.17 (C, C-5), 165.54 (C, NCO),
197.30 (C, COCH3). IR (KBr, cmꢀ1): ~n¼3367ðsÞ, 3093
(m), 2930 (m), 2873 (m), 1702 (m), 1635 (m), 1617 (m),
1585 (m), 1529 (s), 1481 (s), 1445 (m), 1401 (m), 1352
(s), 1204 (m), 1093 (m), 922 (w), 892 (m), 805 (s), 733
(s), 691 (m), 674 (m), 605 (w). UV–vis (CH3CN, nm):
lmax (log 3)¼264.5 (4.17), 207.0 (4.29). MS-FAB:
m/z (%)¼305 ([M+H]+). Anal. Calcd for C19H16N2O2:
C, 74.98; H, 5.30; N, 9.20. Found: C, 74.77; H, 5.40; N,
9.15.
3.2.18. (E)-5-(2-Oxopropylidene)-1-(2-tolyl)-3-(2-tolyl-
amino)-2,5-dihydropyrrol-2-one (3r). Starting with acetyl-
acetone (600 mg, 0.62 ml, 6.0 mmol) and oxalic acid–bis(2-
tolylimidoyl) chloride (1.83 g, 6.0 mmol), 3r was isolated as
1
a yellow solid (797 mg, 40%, E/Z¼5:3). H NMR (CDCl3,
200 MHz): d¼2.24, 2.35, 2.37, 2.40 (s, 3H, COCH3), 5.36
(s, 1H, CHCOCH3, Z-isomer), 5.89 (s, 1H, CHCOCH3,
E-isomer), 6.14 (s, 1H, CH, Z-isomer), 7.03–7.15 (m, 2H,
4-H, Tol), 7.21–7.38 (m, 6H, Tol+NH), 7.44 (d, J¼7.9 Hz,
1H, Tol), 7.50 (d, J¼7.7 Hz, 1H, Tol). 13C NMR
(CDCl3, 50.3 MHz) E-isomer: d¼17.34, 18.28 (ArCH3),
31.73 (COCH3), 97.64 (CH, CHCOCH3), 99.55 (CH,
C-4), 118.05, 122.35, 123.94, 125.84, 126.29 (CH, Tol),
127.42 (C), 127.46, 130.52, 131.01 (CH, Tol), 132.67,
137.36, 140.73, 142.22, 150.85 (C), 165.66 (C, NCO),
197.32 (C, COCH3); Z-isomer: d¼17.34, 18.28 (ArCH3),
30.69 (COCH3), 98.41 (CH, CHCOCH3), 102.88 (CH,
C-4), 117.79, 122.29, 123.90, 126.15, 126.37, 127.29 (CH,
3.2.21. (5E)-5-(3-Oxobutan-2-ylidene)-1-phenyl-3-(phe-
nylamino)-1H-pyrrol-2(5H)-one (3u). Starting with a THF
solution (40 ml) of LDA (6.9 mmol, 2.3 equiv), 3-methyl
2,4-pentanedione (3.0 mmol, 0.343 g) and a THF solution
(40 ml) of oxalic acid–bis(phenylimidoyl) chloride
(3.0 mmol, 0.83 g), 3u was isolated after chromatography
(n-hexane/EtOAc¼20:1) as a yellow solid (0.50 g, 58%). 1H
NMR (CDCl3, 250 MHz): d¼2.16 (s, 3H, CH3C), 2.34 (s,
3H, CH3CO), 6.54 (s, 1H, C4), 7.08–7.13 (m, 3H, Ar),
7.19–7.26 (m, 3H, Ar), 7.35–7.49 (m, 4H, 3H, Ar, NH),

12982
V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
7.67–7.70 (dd, 2H, 2CH, Ar). 13C NMR (CDCl3, 62.5 MHz):
d¼13.8, 29.9 (CH3), 100.0 (CH), 108.8 (C), 117.2, 118.5,
123.3, 124.1, 124.9, 125.8, 126.2, 129.0, 129.2, 129.5 (CH),
136.5, 139.9, 144.0, 151.6 (C), 161.2, 199.7 (CO). IR (KBr,
cmꢀ1): ~n¼3354ðmÞ, 3351 (m), 2925 (w), 2361 (w), 1687
(s), 1668 (s), 1568 (s), 1531 (s), 1493 (s), 1358 (s), 1321
(s), 1229 (s), 1068 (s), 974 (s), 941 (s), 752 (s), 688 (s), 584
(m). UV–vis (CH3CN, nm): lmax (log 3)¼256.5 (4.17),
392.27 (4.23). MS (EI, 70 eV): m/z (%)¼319 (M++1, 24),
318 (M+, 100), 303 (24), 275 (46), 240 (18), 198 (21), 156
(33), 144 (22), 77 (30), 43 (18). HRMS (EI, 70 eV): calcd
for C26H20O2N2: 364.1423; found: 364.1423ꢃ2 ppm ([M]+).
8.36 (br, 1H, NH). 13C NMR (CDCl3, 62.5 MHz): d¼17.9
(CH3), 18.9, 26.9 (CH2), 116.2, 122.6, 122.7 (CH), 122.9
(C), 126.2, 127.4, 127.5, 127.6 (CH), 128.5 (C), 128.9,
130.9, 131.7 (CH), 134.7, 139.5, 154.2, 157.0, 157.0 (C),
157.3, 178.4 (CO). MS (EI, 70 eV): m/z (%)¼332 (M+, 8),
331 (67), 329 (100), 197 (20), 159 (13), 141 (56), 126.8
(32), 114.2 (77), 90.9 (64), 28 (75). IR (KBr, cmꢀ1):
~n¼3438ðbr sÞ, 3365 (s), 1698 (s), 1643 (s), 1594 (s), 1567
(s), 1500 (s), 1458 (s), 1424 (s), 1156 (m), 750 (s). UV–vis
(CH3CN, nm): lmax (log 3)¼213.3 (4.36), 218.8 (4.34),
278.1 (4.16), 288.9 (4.15), 312.54 (5.14). HRMS (EI,
70 eV): calcd for C21H17O3N: 331.1208; found:
331.1208ꢃ2 ppm ([M]+).
3.3. General procedure for the synthesis of 5-alkylidene-
3-hydroxy-2,5-dihydropyrrol-2-ones (4) and pyran-4-
ones (5)
3.3.3. 5,6-Dihydro-N-(2-methoxyphenyl)-4-oxo-4H-
benzo[h]chromene-2-carboxamide (5c). To a THF solu-
tion (50 ml) of 3c (120 mg) was added an aqueous solution
of HCl (40 ml, 10%). The solution was stirred for 24 h at
20 ꢁC. The mixture was purified by chromatography (silica
gel, n-hexane/EtOAc¼5:1/3:1) to give 5c as a colourless
The 3-arylamino-2,5-dihydropyrrol-2-one 3 was dissolved
in THF at room temperature. To this solution, an aqueous so-
lution of hydrochloric acid (15 ml, 10%) was added under
vigorous stirring. The temperature of the mixture rised to
ca. 40 ꢁC during the addition and the colour changed from
yellow to orange. After stirring for 24 h at 25 ꢁC, the pale
yellow solution was poured into 150 ml of water. The
organic and the aqueous layer were separated and the latter
was extracted with 3ꢂ100 ml of diethyl ether. The combined
organic layers were dried (MgSO4), filtered and the filtrate
was concentrated in vacuo. The residue was purified by chro-
matography (silica gel, pentane/ether¼10:1/1:1) to give 4
and/or 5 as yellow crystals.
1
solid (68 mg, 85%). H NMR (CDCl3, 250 MHz): d¼2.87
(t, 2H, CH2), 2.97 (t, 2H, CH2), 4.03 (s, 3H, CH3), 6.96–
7.06 (m, 1H, Ar), 7.13–7.18 (m, 1H, Ar), 7.24 (s, 1H,
CHCO), 7.31 (d, 1H, Ar), 7.41–7.46 (m, 1H, Ar), 7.44 (d,
2H, Ar), 7.85 (d, 1H, Ar), 8.51 (d, 1H, Ar), 9.37 (s, 1H,
NH). 13C NMR (CDCl3, 62.5 MHz): d¼18.9, 26.9 (CH2),
56.3 (CH3O), 110.3, 115.6, 119.9, 121.7 (CH), 122.5 (C),
122.9, 125.2 (CH), 126.6 (C), 127.3 (CH), 127.6 (C),
128.9, 131.7 (CH), 139.4, 148.3, 154.1, 156.4 (C), 157.2,
178.6 (CO). IR (KBr, cmꢀ1): ~n¼3408ðmÞ, 2942 (w), 1765
(m), 1694 (s, 1651 (s), 1603 (s), 1536 (s), 1463 (s), 1417
(s), 1333 (m), 1253 (s), 1159 (m), 1122 (m), 1024 (m),
758 (m), 633 (m), 543 (w). UV–vis (CH3CN, nm): lmax
(log 3)¼213.17 (4.40), 219.4 (4.40), 252.0 (4.14), 290.5
(4.18), 311.7 (4.24). MS (EI, 70 eV): m/z (%)¼348.7
(M++1, 2), 347 (M+, 19), 347 (88), 346 (100), 197 (20),
171 (20), 141 (29), 114 (21), 92 (8), 28 (6). HRMS (EI,
70 eV): calcd for C21H17O4N: 347.1158; found:
347.1158ꢃ2 ppm ([M]+).
3.3.1. 5,6-Dihydro-4-oxo-N-phenyl-4H-benzo[h]chro-
mene-2-carboxamide (5a). To a THF solution (25 ml) of
3a (40 mg) was added an aqueous solution of HCl (15 ml,
10%). The solution was stirred for 24 h at 20 ꢁC. The mix-
ture was purified by chromatography (silica gel, n-hexane/
EtOAc¼5:1/3:1) to give 5a as a yellow solid (25 mg,
1
75%). H NMR (CDCl3, 250 MHz): d¼2.87 (t, 2H, CH2),
2.94 (t, 2H, CH2), 7.19–7.22 (m, 1H, Ar), 7.27 (s, 1H,
CH–CO), 7.33–7.34 (d, 2H, Ar), 7.41–7.46 (m, 2H,), 7.68
(d, 2H, Ar), 7.74–7.66 (d, 2H, Ar), 8.31 (s, 1H, NH). 13C
NMR (CDCl3, 62.5 MHz): d¼19.0, 26.9 (CH2), 116.1,
120.3, 123.1, 126.2, 127.5, 128.9, 129.6, 131.8 (CH),
136.6, 139.4, 154.2, 157.2 (C), 157.5, 178.4 (CO). MS (EI,
70 eV): m/z (%)¼318.8 (M++1, 1.4), 317.8 (M+, 13), 317
(66), 316 (100), 287.8 (3), 197 (25), 172 (6), 141 (28), 127
(17), 114 (25), 93 (4), 77.3 (8). IR (KBr, cmꢀ1): ~n¼
3426ðbr mÞ, 3304 (m), 3296 (m), 2855 (m), 1685 (m),
1643 (s), 1600 (s), 1542 (s), 1426 (s), 1324 (m), 1248 (m),
1155 (m), 764 (m), 697 (m). UV–vis (CH3CN, nm): lmax
(log 3)¼220.3 (4.13), 280.8 (4.05), 288.8 (4.05), 310.4
(4.00). HRMS (EI, 70 eV): calcd for C20H15O3N:
317.1052; found: 317.1052ꢃ2 ppm ([M]+).
3.3.4. (E)-3-Hydroxy-1-(4-methoxyphenyl)-5-(1-oxo-
1,2,3,4-tetrahydro-2-naphthylidene)-2,5-dihydropyrrol-
2-one (4d). Starting with 3d (60 mg, 0.13 mmol), 4d was
isolated as an orange solid (10 mg, 23%). 1H NMR
(CDCl3, 250 MHz): d¼3.00+3.08 (2d, J¼6.7 Hz, 4H,
2CH2), 3.82 (s, 3H, OMe), 6.67 (br s, 1H, OH), 6.93 (d,
3
3J¼8.8 Hz, 2H, AA0, PMP), 7.14 (d, J¼8.9 Hz, 2H, XX0,
3
3
PMP), 7.27 (d, J¼6.4 Hz, 1H, Ar), 7.35 (t, J¼7.5 Hz,
3
1H, Ar), 7.48 (d, J¼7.5 Hz, 1H, Ar), 7.61 (s, 1H, C-4),
8.05 (d, 3J¼7.7 Hz, 1H, Ar). 13C NMR (CDCl3,
50.3 MHz): d¼25.31, 28.59 (CH2), 55.65 (OCH3), 102.62
(CH, C-4), 113.28 (C), 115.20, 120.13 (PMP), 127.03,
127.56, 128.26 (CH, Ar), 131.50, 132.20 (C), 133.06 (CH,
Ar),134.64, 143.21, 156.60, 156.82 (C), 166.05 (NCO),
207.34 (CO). IR (KBr, cmꢀ1): ~n¼3339ðsÞ, 3294 (w), 2957
(w), 2929 (w), 2854 (w), 1763 (s), 1658 (m), 1636 (s),
1599 (s), 1564 (s), 1541 (m), 1512 (s), 1456 (w), 1343
(m), 1279 (m), 1237 (s), 1177 (m), 1156 (m), 1087 (m),
1031 (m), 923 (m), 801 (m). UV–vis (CH3CN, nm): lmax
(log 3)¼431.9 (4.13), 296.2 (3.92), 247.6 (3.86). MS (EI,
70 eV): m/z (%)¼347 ([M]+, 100), 300 (20), 186 (56), 123
(28). HRMS (EI, 70 eV): calcd for C21H17NO4: 347.1158;
found: 347.1158ꢃ2 ppm ([M]+). Anal. Calcd for
3.3.2. 5,6-Dihydro-4-oxo-N-(2-tolyl)-4H-benzo[h]chro-
mene-2-carboxamide (5b). To a THF solution (40 ml) of
3b (80 mg) was added an aqueous solution of HCl (30 ml,
10%). The solution was stirred for 24 h at 20 ꢁC. The mix-
ture was purified by chromatography (silica gel, n-hexane/
EtOAc¼5:1/3:1) to give 5b as a yellow solid (60 mg,
1
95%). H NMR (CDCl3, 250 MHz): d¼2.45 (s, 3H, CH3),
2.88 (m, 2H, CH2), 2.99 (m, 2H, CH2), 7.15–7.20 (m, Ar),
7.29–7.48 (m, Ar), 7.73 (d, 1H, Ar), 8.13 (d, 1H, CH),

V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
12983
C21H17NO4: C, 72.61; H, 4.93; N, 4.03. Found: C, 72.45; H,
4.84; N, 3.89.
3.3.7. 2-[N-(Methoxyphenyl)carbamoyl]-5,6,6a,7,8,9,
10,10a-octahydrobenzo[h]chromone (5f). Starting with
3f (129 mg, 0.28 mmol), 5f was isolated as a pale yellow
solid (77 mg, 77%). 1H NMR ([D6]DMSO, 250 MHz):
d¼1.15–1.38 (m, 6H, CH2), 1.40–1.95 (m, 4H, CH2),
2.00–2.45 (m, 4H, CH2, CH), 3.33 (s, 3H, OMe), 5.74 (br
3.3.5. 2-[N-(Methoxyphenyl)carbamoyl]-5,6-dihydro-
benzo[h]chromone (5d). Starting with 3d (60 mg,
0.13 mmol), 5d was isolated as a colourless solid (30 mg,
1
3
63%). H NMR (CDCl3, 250 MHz): d¼2.84 (d, J¼6.1 Hz,
s, 1H, NH), 6.84 (s, 1H, C-3), 6.94 (d, J¼9.0 Hz, 2H,
3
2H, CH2, C-5), 2.91 (d, J¼6.1 Hz, 2H, CH2, C-6), 3.81 (s,
3H, OMe), 6.91 (d, J¼8.3 Hz, 2H, C-30, C-50), 7.21 (s, 1H,
C-3), 7.29 (d, J¼7.2 Hz, 1H, C-9), 7.40 (t, J¼5.9 Hz, 2H,
C-7, C-8), 7.61 (d, J¼8.7 Hz, 2H, C-20, C-60), 7.75 (d,
J¼6.2 Hz, 1H, C-10), 8.50 (br s, 1H, NH). 13C NMR
(CDCl3, 50.3 MHz): d¼18.83 (CH2, C-5), 26.78 (CH2, C-
6), 55.55 (OMe), 114.54 (CH, C-30, C-50), 115.70 (CH, C-
3), 122.36 (CH, C-20, C-60), 122.64 (C, C-4a), 122.94 (CH,
C-10), 127.19 (CH, C-7), 127.38 (C, C-10a), 128.59 (CH,
C-9), 129.55 (C, C-10), 131.52 (CH, C-8), 139.15 (C, C-
6a), 154.25 (C, C-2), 156.94 (C, C-40), 157.26 (C, C-10b),
157.54 (NCO), 178.12 (CO). IR (KBr, cmꢀ1):
~n¼3332ðmÞ, 3304 (m), 2957 (w), 1685 (m), 1638 (s),
1618 (s), 1549 (s), 1511 (s), 1437 (s), 1415 (m), 1249 (s),
1173 (m), 1131 (w), 1090 (m), 1033 (m), 944 (w), 831
(m), 807 (m). UV–vis (CH3CN, nm): lmax (log 3)¼311.3
(4.16), 289.9 (4.16), 249.9 (4.01), 218.9 (4.32). MS
(EI, 70 eV): m/z (%)¼347 ([M]+, 100), 197 (20), 141
(36), 122 (60), 115 (40), 95 (24). HRMS (EI, 70 eV):
calcd for C21H17NO4: 347.1158; found: 347.1158ꢃ2 ppm
([M]+).
AA0, PMP), 7.61 (d, J¼9.0 Hz, 2H, XX0, PMP). 13C
NMR ([D6]DMSO, 50.3 MHz): d¼20.91, 25.39, 25.67,
27.13, 27.81, 32.57 (6CH2), 39.08 (CH, overlapped by the
DMSO-signal), 43.08 (CH), 55.16 (OCH3), 113.26 (CH,
C-3), 113.79, 122.66 (CH, PMP), 122.76, 130.41, 155.24,
156.27, 157.44 (C), 164.35 (NCO), 177.96 (CO). IR (KBr,
cmꢀ1): ~n¼3319ðsÞ, 3082 (w), 2927 (s), 2860 (m), 1687
(s), 1639 (s), 1613 (s), 1606 (s), 1582 (s), 1550 (s), 1511
(s), 1436 (s), 1413 (m), 1329 (m), 1259 (s), 1241 (s), 1180
(m), 1167 (m), 1029 (s), 1000 (m), 968 (m), 879 (m), 840
(s), 683 (m). UV–vis (CH3CN, nm): lmax (log 3)¼284.2
(3.99), 250.3 (3.83). MS (EI, 70 eV): m/z (%)¼353 ([M]+,
100), 298 (6), 176 (20), 122 (16). HRMS (EI, 70 eV): calcd
for C21H23NO4: 353.1627; found: 353.1627ꢃ2 ppm ([M]+).
Anal. Calcd for C21H23NO4: C, 71.37; H, 6.56. Found: C,
71.11; H, 6.48.
3.3.8. 5,6,7,8-Tetrahydro-8-methyl-4-oxo-N-phenyl-4H-
chromene-2-carboxamide (5g). To a THF solution (40 ml)
of 3g (100 mg) was added an aqueous solution of HCl
(30 ml, 10%). The solution was stirred for 24 h at 20 ꢁC.
The mixture was purified by chromatography (silica gel,
n-hexane/EtOAc¼5:1/3:1) to give 5g as a yellow solid
(62 mg, 79%). 1H NMR (CDCl3, 250 MHz): d¼1.39 (d,
3H, CH3), 1.60–1.70 (m, 1H, CH2), 1.81–1.89 (m, 1H,
CH2), 1.95–2.06 (m, 1H, CH2), 2.52 (m, 1H, CH2), 2.89 (m,
1H, CHCH3), 7.15 (s, 1H, C4), 7.38–7.40 (m, 2H, Ar),
7.63–7.66 (d, 2H, Ar), 8.21 (s, 1H, NH). 13C NMR (CDCl3,
62.5 MHz): d¼19.0 (CH3), 19.2, 27.2 (CH2), 30.7 (CH),
32.5 (CH3), 115.1 (CH), 120.6 (2CH), 124.6, 125.8 (CH),
129.5 (2CH), 136.3, 154.4, 157.2 (C), 165.8, 179.3 (CO).
IR (KBr, cmꢀ1): ~n¼3318ðmÞ, 3290 (m), 2936 (m), 1696
(s), 1643 (s), 1613 (s), 1587 (s), 1553 (s), 1434 (s), 1321
(s), 1167 (m), 957 (m), 759 (s), 694 (m). UV–vis (CH3CN,
nm): lmax (log 3)¼221.4 (4.31), 274.9 (4.14). MS (EI,
70 eV): m/z (%)¼284 (M++1, 16), 283 (M+, 100), 268 (55),
213 (6), 163 (14), 146 (89), 91 (10), 77 (15), 70 (12).
HRMS (EI, 70 eV): calcd for C17H17O3N: 283.1208; found:
283.1208ꢃ2 ppm ([M]+).
Crystal data: C21H17NO4: Mr¼347.36, monoclinic, space
˚
˚
group P21/c, a¼14.564(3) A, b¼15.281(3) A, c¼7.217(1)
A,b¼93.22(3) , V¼1603.6(5) A , Z¼4,rcalcd¼1.439 g cmꢀ1
,
3
ꢁ
˚
˚
F(000)¼728, m(Cu Ka)¼0.820 mmꢀ1, 3.04ꢁ<q<59.83ꢁ,
5353 reflections were collected, of which 2312 were indepen-
dent (Rint¼0.0143) and used for the refinement; 241 param-
P
eters were refined. The R values were: R1¼ jFoꢀFcj=
P
P
2
Fo¼0.0261 for I>2s(I) and wR1¼½ wðF2o ꢀ Fc2Þ =
P
1=2
F4cꢄ ¼0:0657 for allꢀd3ata; max/min residual electron
˚
density:0.143/ꢀ0.146 e A
.
3.3.6. 5,6-Dihydro-N-(naphthalene-1-yl)-4-oxo-4H-
benzo[h]chromene-2-carboxamide (5e). To a THF solu-
tion (25 ml) of 3e (80 mg) was added an aqueous solution
of HCl (30 ml, 10%). The solution was stirred for 24 h at
20 ꢁC. The mixture was purified by chromatography (silica
gel, n-hexane/EtOAc¼5:1/3:1) to give 5e as a yellow solid
(55 mg, 92%). 1H NMR (CDCl3, 250 MHz): d¼2.91 (t, 2H,
CH2), 2.98 (t, 2H, CH2), 7.35 (s, 1H, C4), 7.45–7.86 (m, 2H,
Ar), 7.55–7.66 (m, 4H, Ar), 7.81–7.86 (m, 2H, Ar), 8.86 (s,
1H, NH). 13C NMR (CDCl3, 62.5 MHz): d¼19.1, 27.0
(CH2), 116.4, 120.1, 121.2, 122.9 (CH), 123.1 (C), 126.1,
126.6, 127.1, 127.2, 127.5 (CH), 127.6 (C), 128.9, 129.4
(CH), 130.9 (C), 131.8 (CH), 134.4, 139.5, 154.2, 157.5
(C), 157.5, 178.4 (CO). MS (EI, 70 eV): m/z (%)¼368
(M++1, 27), 367 (M+, 65), 348 (21), 320 (11), 222 (24),
195 (47), 167 (10), 141 (40), 114 (84), 70 (9). IR (KBr,
cmꢀ1): ~n¼3442ðmÞ, 1693 (s), 1652 (s), 1629 (s), 1599 (s),
1541 (s), 1498 (s), 1421 (s), 1344 (m), 1258 (m), 1157
(m), 984 (m), 881 (m), 772 (m), 757 (m). UV–vis
(CH3CN, nm): lmax (log 3)¼220.6 (4.83), 290.5 (4.19),
312.6 (4.21). HRMS (EI, 70 eV): calcd for C24H17O3N:
367.1208; found: 367.1208ꢃ2 ppm ([M]+).
3.3.9. 5,6,7,8-Tetrahydro-8-methyl-4-oxo-N-(2-tolyl)-4H-
chromene-2-carboxamide (5h). To a THF solution (50 ml)
of 3h (110 mg) was added an aqueous solution of HCl
(30 ml, 10%). The solution was stirred for 24 h at 20 ꢁC.
The mixture was purified by chromatography (silica gel,
n-hexane/EtOAc¼5:1/3:1) to give 5h as a yellow solid
1
(75 mg, 89%). H NMR (CDCl3, 250 MHz): d¼1.42 (d,
3H, CH3), 1.62–1.69 (m, 2H, CH2), 1.81–1.87 (m, 1H,
CH2CH2), 1.98–2.05 (m, 1H, CH2CH2), 2.19 (s, 3H, CH3),
2.47–2.54 (m, 2H, CH2), 2.89 (m, 1H, CHCH3), 7.11 (d,
1H, Ar), 7.14 (s, 1H, C4), 7.17 (d, 1H, Ar), 7.23–7.30 (m,
1H, Ar), 8.09 (d, 1H, Ar), 8.26 (s, 1H, NH). 13C NMR
(CDCl3, 62.5 MHz): d¼17.7, 18.8 (CH3), 19.4, 21.7, 30.8
(CH2), 32.5, 114.9, 122.3 (CH), 124.6 (C), 126.0, 127.4
(CH), 128.3 (C), 130.8 (CH), 134.7, 154.5, 157.0 (C),
165.6, 179.3 (CO). IR (KBr, cmꢀ1): ~n¼3428ðbr sÞ, 2940

12984
V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
(m), 1689 (s), 1655 (s), 1609 (s), 1591 (s), 1529 (s), 1457 (s),
1417 (s), 1309 (m), 1255 (m), 1145 (s), 1034 (w), 773 (m),
590 (m). UV–vis (CH3CN, nm): lmax (log 3)¼220.5 (4.26),
268.9 (4.02). MS (EI, 70 eV): m/z (%)¼298 (M+, 18), 297
(94), 282 (35), 268 (7), 227 (9), 186 (14), 160 (100), 131
(10), 106 (20), 77 (13). HRMS (EI, 70 eV): calcd for
C18H19O3N: 297.1365; found: 297.1365ꢃ2 ppm ([M]+).
Anal. Calcd for C18H19O3N: C, 72.69; H, 6.46. Found: C,
72.78; H, 6.72.
13C NMR (CDCl3, 50.3 MHz): d¼20.03, 27.45, 40.34
(CH2), 101.51 (CH, C-4), 114.61 (C), 117.90, 123.66,
129.73 (CH, Ph), 132.62, 138.92, 153.72 (C), 166.88
(NCO), 207.64 (CO). IR (KBr, cmꢀ1): ~n¼3289ðsÞ, 3132
(m), 2956 (m), 2927 (m), 2854 (w), 1789 (s), 1734 (w),
1696 (s), 1641 (s), 1599 (s), 1575 (s), 1544 (s), 1501 (m),
1445 (s), 1324 (s), 1288 (m), 1272 (m), 1227 (m), 1201
(s), 1182 (m), 1086 (m), 1018 (m), 972 (s), 838 (m), 816
(m), 770 (m), 751 (s), 687 (m). UV–vis (CH3CN, nm):
lmax (log 3)¼398.7 (4.33), 294.6 (3.69), 251.6 (4.02). MS
(EI, 70 eV): m/z (%)¼255 ([M]+, 100), 240 (8), 213 (8),
154 (20), 77 (70). HRMS (EI, 70 eV): calcd for
C15H13NO3: 255.0895; found: 255.0895ꢃ2 ppm ([M]+).
Anal. Calcd for C15H13NO3: C, 70.58; H, 5.13; N, 5.49.
Found: C, 70.59; H, 5.15; N, 5.28.
3.3.10. 5,6,7,8-Tetrahydro-N-(2-methoxyphenyl)-8-
methyl-4-oxo-4H-chromene-2-carboxamide (5i). To a THF
solution (50 ml) of 3i (120 mg) was added an aqueous solu-
tion of HCl (15 ml, 10%). The solution was stirred for 24 h at
20 ꢁC. The mixture was purified by chromatography (silica
gel, n-hexane/EtOAc¼5:1/3:1) to give 5i as a slightly
pink solid (67 mg, 75%). 1H NMR (CDCl3, 250 MHz):
d¼1.43 (d, 3H, CH3), 1.58 (m, 2H, CH2), 1.85 (m, 1H,
CH2), 2.07 (m, 1H, CH2), 2.45 (m, 1H, CH2), 2.58 (m, 1H,
CH2), 2.95 (m, 1H, CHCH3), 3.95 (s, 3H, CH3O), 6.93–
6.95 (d, 1H, Ar), 7.02–7.04 (m, 1H, Ar), 7.11–7.14 (m,
1H, Ar), 7.11 (s, 1H, C4), 8.48 (d, 1H, CH), 9.12 (s, 1H,
NH). 13C NMR (CDCl3, 62.5 MHz): d¼18.3 (CH3), 19.8,
21.8 (CH2), 31.0 (CH), 32.7 (CH2), 56.2 (CH3), 110.3,
114.6, 120.1, 121.6 (CH), 124.4 (C), 125.2 (CH), 126.6,
148.4, 154.6, 156.7 (C), 165.6, 179.4 (CO). IR (KBr,
cmꢀ1): ~n¼3438ðbr mÞ, 3379 (s), 2941 (m), 1686 (s), 1654
(s), 1629 (s), 1603 (s), 1530 (s), 1486 (s), 1464 (s), 1629
(s), 1603 (s), 1530 (s), 1486 (s), 1464 (s), 1416 (s), 1336
(m), 1258 (s), 660 (m), 554 (w). UV–vis (CH3CN, nm):
lmax (log 3)¼220.9 (4.33), 280.3 (4.03). MS (EI, 70 eV):
m/z (%)¼315 (M++2, 2), 314 (M++1, 20), 313 (M+, 100),
298 (33), 284 (5), 202 (8), 176 (54), 135 (11), 123 (8), 92
(10), 70 (9), 53 (3). HRMS (EI, 70 eV): calcd for
C18H19NO4: 313.1314; found: 313.1314ꢃ2 ppm ([M]+).
3.3.13. (E)-3-Hydroxy-5-(1-oxo-indan-2-ylidene)-1-phenyl-
2,5-dihydropyrrol-2-one (4l). Starting with 3l (90 mg,
0.24 mmol), 4l was isolated as a yellow solid (71 mg, 99%;
E-isomer: 36 mg, 50%, E/Z>98:2; Z-isomer: 35 mg, 49%,
1
E/Z<2:98). H NMR (CDCl3, 600 MHz) E-isomer: d¼3.95
3
(s, 2H, CH2), 6.83 (br s, 1H, OH), 7.12 (t, J¼7.7 Hz, 1H,
3
Ph, C-40), 7.21 (d, J¼7.8 Hz, 2H, Ph, C-20, C-60), 7.40 (t,
3
4
3J¼7.7 Hz, 2H, Ph, C-30, C-50), 7.42 (td, J¼7.7 Hz, J¼
3
2.2 Hz, 1H, indane, C-600), 7.52 (t, J¼8.3 Hz, 1H, indane,
3
4
C-400), 7.60 (td, J¼7.7 Hz, J¼1.5 Hz, 1H, indane, C-500),
7.70 (s, 1H, CH, C-4), 7.82 (d, 3J¼7.7 Hz, 1H, indane,
C-700); Z-isomer: d¼5.29 (s, 2H, CH2), 6.93 (br s, 1H, OH),
7.19–7.24 (m, 3H, Ph: C-40, indane, C-400, C-600), 7.26–7.30
3
(m, 3H, Ph: C-20, C-60, indane, C-500), 7.45 (t, J¼7.9 Hz,
3
2H, Ph, C-30, C-50), 7.54 (d, J¼7.9 Hz, 1H, indane, C-700),
7.89 (s, 1H, C-4). 13C NMR (CDCl3, 150.8 MHz) E-isomer:
d¼30.21 (CH2), 101.79 (CH, C-4), 113.67 (C, C-5), 118.07
(CH, Ph, C-20, C-60), 123.62 (CH, indane, C-700), 123.96
(CH, Ph, C-40), 126.21 (CH, indane, C-400), 127.57 (CH,
indane, C-600), 129.84 (CH, Ph, C-30, C-50), 132.97 (C, C-3,
C–OH), 134.41 (CH, indane, C-500), 138.80 (C, Ph, C-10),
139.85 (C, indane, C-7a00), 148.04 (C, indane, C-3a00), 154.94
(C, indane, C-200), 166.57 (NCO), 193.72 (CO); Z-isomer:
d¼44.57 (CH2), 101.49 (CH, C-4), 116.23 (C, C-5), 118.30
(CH, Ph, C-20, C-60), 123.28 (CH, indane, C-700), 124.27
(CH, Ph, C-40), 125.33 (CH, indane, C-400), 128.16 (CH,
indane, C-600), 129.92 (CH, Ph, C-30, C-50), 133.38 (C, C-3,
C–OH), 134.24 (CH, indane, C-500), 138.70 (C, Ph, C-10),
139.82 (C, indane, C-7a00), 147.93 (C, indane, C-3a00), 155.79
(C, indane, C-200), 166.16 (NCO), 193.29 (CO). IR (KBr,
cmꢀ1): ~n¼3335ðmÞ, 3065 (w), 3017 (w), 2960 (w), 2918
(w), 2850 (w), 1793 (s), 1771 (s), 1683 (s), 1637 (s), 1610
(s), 1591 (s), 1577 (s), 1537 (s), 1445 (m), 1329 (m), 1265
(s), 1218 (m), 1137 (m), 1064 (m), 918 (s), 798 (w), 749
(m), 733 (m). UV–vis (CH3CN, nm): lmax (log 3)¼425.0
(3.98), 290.5 (3.65), 240.0 (3.73). MS (EI, 70 eV): m/z
(%)¼303 ([M]+, 100), 259 (40), 228 (65), 144 (24). HRMS
(EI, 70 eV): calcd for C19H13NO3: 303.0895; found:
303.0895ꢃ2 ppm ([M]+).
3.3.11. 2-[N-(Methoxyphenyl)carbamoyl]-8-methyl-
5,6,7,8-tetrahydrochromone (5j). Starting with 3j
(21 mg, 0.05 mmol), 5j was isolated as a colourless solid
1
(10 mg, 61%). H NMR (CDCl3, 250 MHz): d¼1.38 (d,
3J¼7.0 Hz, 3H, CHCH3), 1.45–2.10 (m, 6H, 3CH2), 2.88
3
(m, 1H, CHCH3), 3.81 (s, 3H, OMe), 6.91 (d, J¼8.9 Hz,
2H, AA0, PMP), 7.14 (s, 1H, C-3), 7.55 (d, 3J¼9.1 Hz, 2H,
XX0, PMP), 8.19 (br s, 1H, OH). 13C NMR (CDCl3,
50.3 MHz): d¼18.93, 21.50, 30.40 (CH2), 30.93 (CHCH3),
32.19 (CHCH3), 55.49 (OCH3), 114.34 (CH, PMP),
114.55 (CH, C-3), 122.11 (CH, PMP), 124.23, 129.29,
154.37, 156.74, 157.24 (C), 165.69 (NCO), 179.21 (CO).
IR (KBr, cmꢀ1): ~n¼3316ðmÞ, 2938 (w), 1688 (m), 1639
(s), 1615 (s), 1602 (s), 1584 (m), 1552 (m), 1528 (m),
1513 (s), 1434 (m), 1414 (w), 1245 (s), 1166 (m), 1030
(m), 840 (w). UV–vis (CH3CN, nm): lmax (log 3)¼279.7
(4.03), 222.0 (4.24). MS (EI, 70 eV): m/z (%)¼313 ([M]+,
100), 298 (16), 176 (24), 122 (28). HRMS (EI, 70 eV): calcd
for C18H19NO4: 313.1314; found: 313.1314ꢃ2 ppm ([M]+).
3.3.12. (E)-3-Hydroxy-5-(2-oxocyclopent-1-ylidene)-1-
phenyl-2,5-dihydropyrrol-2-one (4k). Starting with 3k
(53 mg, 0.16 mmol), 4k was isolated as a yellow solid
(39 mg, 95%). 1H NMR (CDCl3, 250 MHz): d¼2.01 (quint,
3J¼7.5 Hz, 2H, CO–CH2CH2), 2.43 (t, 3J¼7.8 Hz, 2H,
3.3.14. 6-Phenyl-2-(phenylcarbamoyl)-4H-pyran-4-one
(5m). Starting with 3m (420 mg, 1.15 mmol), 5m was iso-
lated as a yellow solid (100 mg, 30%). 1H NMR
([D6]DMSO, 250 MHz): d¼6.99 (d, J¼2.1 Hz, 1H, C-5),
3
7.12 (d, J¼2.1 Hz, 1H, C-3), 7.18 (t, J¼7.2 Hz, 1H, Ph),
3
3
CCH2CH2), 2.91 (t, J¼7.2 Hz, 2H, CH2CO), 6.82 (br s,
7.40 (t, J¼7.8 Hz, 2H, Ph), 7.50–7.62 (m, 3H, Ph), 7.74
3
3
1H, OH), 7.07–7.17 (m, 3H, Ar), 7.35–7.44 (m, 3H, Ar).
(d, J¼8.1 Hz, 2H, Ph), 8.08 (t, J¼7.8 Hz, 2H, Ph), 9.50

V. T. H. Nguyen et al. / Tetrahedron 63 (2007) 12975–12985
12985
(br s, 1H, NH). 13C NMR (CDCl3, 50.3 MHz): d¼112.07,
115.53 (CH, C-3, C-5), 121.11, 124.85, 126.51, 128.72,
128.98 (CH, Ph), 130.35 (C), 131.72 (CH, Ph), 137.54,
156.21, 157.81, 162.85 (NCO), 178.60 (CO). IR (KBr,
cmꢀ1): ~n¼3424ðsÞ, 3331 (s), 1693 (w), 1639 (s), 1602 (m),
1549 (w), 1498 (w), 1448 (w), 1409 (m), 1324 (w), 1049
(m), 1028 (s), 1003 (s), 826 (w), 767 (m), 689 (w). UV–vis
(CH3CN, nm): lmax (log 3)¼278.1 (3.52). MS (EI, 70 eV):
m/z (%)¼291 ([M]+, 50), 186 ([MꢀCOPh]+, 100), 172
(18), 105 (24), 77 (18), 69 (40). HRMS (EI, 70 eV): calcd
for C18H13NO3: 291.0895; found: 291.0895ꢃ2 ppm ([M]+).
Chung, M.-I.; Lu, C.-M.; Huang, P.-L.; Lin, C.-N.
Phytochemistry 1995, 40, 1279.
4. Kazlauskas, R.; Lidgard, R. R. O.; Wells, R. J. Tetrahedron
Lett. 1978, 3165.
5. (a) Feist, H. Annalen 1890, 257, 258; (b) Feist, H. Chem. Ber.
1895, 28, 1823; (c) Lehmann, K.; Grabow, J. Chem. Ber.
1935, 68, 704; (d) Heyns, C.; Vogelsang, F. Chem. Ber. 1954,
87, 1440; (e) Hauser, C. R.; Harris, T. M. J. Am. Chem. Soc.
1958, 80, 6360; (f) Yamamoto, M.; Sugiyama, N. Bull. Chem.
Soc. Jpn. 1975, 48, 508; Review: (g) Harris, T. M.; Harris,
C. M. Tetrahedron 1977, 33, 2159; (h) Griffin, D. A.; Leeper,
F. J.; Staunton, J. J. Chem. Soc., Perkin Trans. 1 1984, 1035;
(i) Yamamoto, M.; Iwasa, S.; Takatsuki, K.; Yamada, K.
J. Org. Chem. 1986, 51, 346; (j) Yamaguchi, M.; Shibato, K.;
Nakashima, H.; Minami, T. Tetrahedron 1988, 44, 4767.
6. Anders, J. T.; Nguyen, V. T. H.; Langer, P. Synlett 2004, 2779.
7. For cyclizations of 1,3-dicarbonyl dianions with oxalic acid–
Acknowledgements
Financial support from the Konrad-Adenauer-Stiftung
(scholarship for J.T.A.), the government of Vietnam (schol-
arship for V.T.H.N.) and the Deutsche Forschungsgemein-
schaft is gratefully acknowledged.
€
bis(imidoyl) dichlorides, see: (a) Langer, P.; Doring, M.
Synlett 2001, 1437; (b) Anders, J. T.; Gorls, H.; Langer, P.
€
Eur. J. Org. Chem. 2004, 1897.
8. For a review of cyclizations of oxalic acid–bis(imidoyl)
References and notes
€
dichlorides, see: Langer, P.; Doring, M. Eur. J. Org. Chem.
2002, 221.
1. Ro€mpp Lexikon Naturstoffe; Fugmann, B., Lane-Fugmann, S.,
Steglich, W., Eds.; Thieme: Stuttgart, 1997.
2. Jaensch, M.; Jakupovic, J.; King, R. M.; Robinson, H.
Phytochemistry 1989, 28, 3497.
3. Artonol C: (a) Aida, M.; Yamaguchi, N.; Hano, Y.; Nomura, T.
Heterocycles 1997, 45, 163; artonin T: (b) Aida, M.;
Shinomiya, K.; Matsuzawa, K.; Hano, Y.; Nomura, T.
Heterocycles 1994, 39, 847; artonin N: (c) Hano, Y.; Inami,
R.; Nomura, T. Heterocycles 1993, 35, 1341; artonin A: (d)
9. Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
10. CCDC-281059 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
deposit@ccdc.cam.ac.uk).
11. Sheldrick, G. M. SHELXL-97, Program for Structure
€
Refinement; Universitat Gottingen: Gottingen, Germany, 1997.
€
€