Synthesis of 2-(alkylamino)-5-{alkyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino} -3,4-furandicarboxylates using a multi-component reaction in water

Article abstract of DOI:10.1016/j.tet.2010.09.032

A simple synthesis of 2-(alkylamino)-5-{alkyl[(2-oxo-2H-chromen-3-yl) carbonyl]amino}-3,4-furandicarboxylates via a one-pot multi-component reaction is described. The reactive 1:1 zwitterionic intermediate generated from the addition of isocyanides to dialkyl acetylenedicarboxylates was trapped at room temperature by coumarin-3-carboxylic acids prepared in situ from a 2-hydroxy aromatic aldehyde and Meldrum's acid to afford the title compounds in good to excellent yields.

Full text of DOI:10.1016/j.tet.2010.09.032

Tetrahedron 66 (2010) 9263e9269
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Synthesis of 2-(alkylamino)-5-{alkyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}-
3,4-furandicarboxylates using a multi-component reaction in water
,
a
a
b
Mehdi Adib a , Ehsan Sheikhi , Azadeh Kavoosi , Hamid Reza Bijanzadeh
*
a School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
b Department of Chemistry, Tarbiat Modarres University, PO Box 14115-175, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 May 2010
Received in revised form 23 August 2010
Accepted 13 September 2010
Available online 17 September 2010
A simple synthesis of 2-(alkylamino)-5-{alkyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarbox-
ylates via a one-pot multi-component reaction is described. The reactive 1:1 zwitterionic intermediate gen-
erated from the addition of isocyanides to dialkyl acetylenedicarboxylates was trapped at room temperature
by coumarin-3-carboxylic acids prepared in situ from a 2-hydroxy aromatic aldehyde and Meldrum’s acid
to afford the title compounds in good to excellent yields.
Ó 2010 Published by Elsevier Ltd.
Keywords:
Furans
Isocyanides
Dialkyl acetylenedicarboxylates
2-Hydroxy aromatic aldehydes
Meldrum’s acid
Multi-component reactions
Synthesis in water
1. Introduction
agrochemical bioregulators, essential oils, cosmetics, dyes, photo-
sensitizers, flavoring and fragrance compounds.10,11 This broad
Multi-component reactions (MCRs) have emerged as an efficient
and powerful tool in modern synthetic organic chemistry due to
their valued features, such as atom economy, straightforward re-
action design and the opportunity to construct target compounds
by the introduction of several diversity elements in a single
chemical event. Typically, purification of products resulting from
MCRs is also simple since all the organic reagents employed are
consumed and are incorporated into the target compound.1 MCRs
leading to interesting heterocyclic scaffolds are particularly useful
for the construction of diverse chemical libraries of ‘drug-like’
molecules. The isocyanide-based MCRs are especially important in
this area.1j,k
Furans, benzofurans, and their reduced forms are important core
structures in many biologically active natural products. Moreover,
they are useful building blocks in the total synthesis of natural
products and pharmaceuticals.2e5 Many naturally occurring furans
have exhibited considerable biological activities, such as antitumor
and cytotoxic properties,6 as well as antimicrobial,7 antispasmodic,8
and several other potentially useful activities.9,10 In addition, furans
are also present in commercially important products, such as
range of applications has made the development of new and effi-
cient furan synthesis very valuable. Consequently, a variety of furan
syntheses have been reported in the literature. Although a lot of
strategies can be found for the synthesis of furans, convergent
synthetic methods from simple and readily available starting ma-
terials without using transition-metal catalysis are still
rare.1g,2a,12e14
Coumarinyl compounds have been extensively used in medici-
nal chemistry. Some examples have been shown to be highly potent
human
b-secretase inhibitors and are used in the treatment of
Alzheimer’s disease. Most of the synthetic medicines containing
a coumarin, are prepared by the reaction between coumarin-3-
carboxylic acids and amines.15
2. Results and discussion
As part of our current studies on the development of new ef-
ficient strategies for the preparation of interesting bioactive mol-
ecules and drug cores,16 herein, we present a new synthetic
method for the construction of 5-amido coumarinyl 2-aminofurans
via a one-pot, isocyanide-based MCR involving commercially
available starting materials. Thus, a mixture of salicylaldehyde 1a,
Meldrum’s acid 2, tert-butyl isocyanide 3a (2 equiv) and dimethyl
* Corresponding author. Tel./fax: þ98 21 66495291; e-mail address: madib@
khayam.ut.ac.ir (M. Adib).
0040-4020/$ e see front matter Ó 2010 Published by Elsevier Ltd.
doi:10.1016/j.tet.2010.09.032

9264
M. Adib et al. / Tetrahedron 66 (2010) 9263e9269
acetylenedicarboxylate (DMAD, 4a) afforded dimethyl 2-(tert-buty-
lamino)-5-{tert-butyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}-3,4-
furandicarboxylate 5a (Scheme 1).
water and an acetone molecule. The 1H NMR spectrum of 5a
exhibited five single sharp lines readily recognized as arising from
the two tert-butyl (
d¼1.43 and 1.49 ppm) groups, two methoxy
NHtBu
O
O
O
O
CO2CH3
CO2CH3
CO2CH3
O
O
C
N
H
tBuNC
+
+
+
2
C
tBu
O
O
O
OH
CO2CH3
2
3a
4a
5a
1a
Scheme 1.
The reaction was carried out in some solvents under similar
conditions at ambient temperature. As disclosed in Table 1, the
maximum yield was observed in water (entry 1).
(
d
¼3.63 and 3.80 ppm) groups, and the coumarin vinylic H atom
¼7.68 ppm). A fairly sharp singlet was seen for the amine NH
(d
group (
d
¼6.84 ppm) along with the characteristic signals with
appropriate chemical shifts and coupling constants for the four
aromatic protons. The 1H decoupled 13C NMR spectrum of 5a
showed 22 distinct resonances in agreement with the proposed
structure. Partial assignments of these resonances are given in the
Experimental section.
Table 1
Solvent effect in the multi-component synthesis of 5a
Entry
Solvent
Time h
Yield of 5a (%)
The 1H and 13C NMR spectra of compounds 5bej were similar to
those of 5a, except for the N-alkyl groups, ester functions and
coumarin moieties, which exhibited characteristic signals with
appropriate chemical shifts and coupling constants (see the
Experimental section).
1
2
3
4
H2O
12
12
12
12
87
70
60
68
CH2Cl2
CHCl3
EtOH
A mechanistic rationalization for this reaction is provided in
Scheme 3. At first, the 2-hydroxy aromatic aldehydes 1 condense
with Meldrum’s acid 2 to produce intermediates 6, which are
readily converted in to coumarin-3-carboxylic acids 7 via an ad-
dition reaction and subsequent acetone elimination. Next, the
In order to show the generality and scope of this new protocol,
we used various 2-hydroxy aromatic aldehydes, dialkyl acetylene-
dicarboxylates, and isocyanides in water. The results are summa-
rized in Scheme 2 and Table 2.
NHR'
O
CO2R"
C
O
O
_
C
O
O
H
O
H O, r.t.
12 h
+
CO R"
+
2
R'
N
+
N
+
C
O
O
OH
R'
R
CO R"
O
O
O
R
CO2R"
4
3
2
5
1
O
O
1c:
Et2N
1d:
1a:
1b:
H
H
H
H
OH
OH
OH
OH
OMe
3a:
3b:
NC
NC
4a: R" = Me; 4b: R" = Et
Scheme 2.
All the reactions were complete within 12 h. The 1H NMR
spectroscopic analysis of the reaction mixtures clearly indicated the
formation of the corresponding 5-amido coumarinyl 2-amino-
furans 5aej in good to excellent yields.
The structures of the isolated products 5aej were deduced on
the basis of IR, 1H and 13C NMR spectroscopy, mass spectrometry,
and elemental analysis. The mass spectrum of 5a displayed the
molecular ion (Mþ) peak at m/z¼498, which was consistent with
the 1:1:2:1 adduct of salicylaldehyde, Meldrum’s acid, tert-butyl
isocyanide, and dimethyl acetylenedicarboxylate with the loss of
reactive 1:1 zwitterionic intermediates 8, generated in situ from
the reaction between isocyanides 3 and dialkyl acetylenedi-
carboxylates 417,1j,k are protonated by 7. Then, the positively
charged ions 9 can be attacked by the carboxylate anions 10 to
form imidoyl carboxylates 11, which undergo a Mumm rear-
rangement18 under the reaction conditions employed, to produce
the a,b-unsaturated intermediates 12. Finally cycloaddition of 12
and another isocyanide molecule gives iminolactone in-
termediates 13, which tautomerize under the reaction condition
to produce 2-aminofurans 5.

M. Adib et al. / Tetrahedron 66 (2010) 9263e9269
9265
Table 2
Synthesis of 5-amido coumarinyl 2-aminofurans 5aej
Product
Structure
Yield %
87
Product
Structure
Yield %
5a
5b
85
88
5c
89
5d
5e
5g
85
90
5f
87
92
5 h
5i
96
5j
83
When the reactions were performed using equivalent ratios of
a 2-hydroxy aromatic aldehyde (1a or 1b), Meldrum’s acid 2,
cyclohexyl isocyanide 3b and, an acetylenic ester (4b or 4a) under
the same reaction conditions, after 5 h, TLC and 1H NMR spectro-
scopic analysis of the reaction mixtures clearly indicated the
formation of corresponding furans 5c and 5d in 12 and 11% yields,
in addition to other products 12a and 12b as the major one in 73
and 70% yields, respectively. The structures of the isolated 2-
({cyclohexyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}carbonyl)-
2-butenedioates 12a and 12b were deduced by 1H and 13C NMR
O
O
O
O
O
O
_
_
H2O
(CH3)2CO
OH
H
O
O
+
OH
O
O
O
O
R
R
OH
R
7
1
2
6
7
O
E
E
E
_
_
C
+
O
_
+
R'
N
+
+
CHE
N
N
R'
O
O
O
E
R'
R
E
10
9
3
4
8
_
C
R'
H
N
+
R'
N
R'
O
O
O
O
O
O
N
CHE
CHE
E
N
N
O
R'
R'
E
E
E
O
O
O
O
R
R
R
11
12
13
5
E = CO2R"
Scheme 3.

9266
M. Adib et al. / Tetrahedron 66 (2010) 9263e9269
spectroscopy and also by elemental analysis (see the Experimental
section). Addition of a second equivalent of an isocyanide 3b or 3a
to the isolated butenedioates 12a and 12b and subsequent cyclo-
addition of the added isocyanide with 12 afforded the corre-
sponding furans 5c and 5k in 92 and 88% yields, respectively
(Scheme 4).
carboxylic acid, as was indicated by TLC monitoring, tert-butyl
isocyanide (0.166 g, 2 mmol), was added to the reaction mixture.
Then dimethyl acetylenedicarboxylate (0.142 g, 1 mmol) was added
at room temperature over 5 min. The reaction mixture was then
allowed to stir for 12 h. Next, the aqueous phase was extracted with
CH2Cl2 (3ꢁ5 mL) and the combined organic layers dried over
NHCy
O
O
O
O
O
CHCO2Et
CO2Et
CyNC (3b)
N
H2O, r.t.
5 h
N
4b
1a
2
3b
5c (12%)
+
+
+
+
H O, r.t.,
Cy
5 h
CO2Et
NH
2
Cy
O
CO2Et
O
O
5c (92%)
12a (73%)
tBu
O
O
O
O
O
CO2Me
CHCO2Me t
BuNC
(3a)
H2O, r.t.
5 h
N
N
1b
+
2
+ 3b
4a
+
5d (11%) +
H2O, r.t.,5 h
CO2Me
Cy
O
Cy
CO2Me
O
O
OMe
OMe
12b (70%)
Scheme 4.
5k (88%)
3. Conclusion
magnesium sulfate. The solvent was evaporated and the residue
was purified by column chromatography using n-hexaneeEtOAc
(3:1) as eluent. The solvent was removed and the product was
obtained.
In summary, we have developed a simple, convergent and highly
efficient one-pot protocol for the synthesis of 5-amido coumarinyl
2-aminofuran derivatives, which are of potential chemical, syn-
thetic and pharmacological interest, based on a new multi-com-
ponent reaction. Considering the availability of the starting
materials, the simple one-pot procedure, high yield of the products,
high flexibility with respect to the substitution pattern at all posi-
tions and the robust nature of this chemical process, provides a very
straightforward route to construct variously substituted furans
without any activation or modification. The simplicity of the present
procedure makes it a viable alternative to the complex multi-step
approaches for the synthesis of bioactive furans.
4.2.1. Dimethyl 2-(tert-butylamino)-5-{tert-butyl[(2-oxo-2H-chro-
men-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5a). Pale yellow
crystals, mp 198e199 ꢀC, yield: 0.434 g, 87%. IR (KBr) (nmax/cmꢂ1):
3338 (NH), 1719, 1670, and 1603 (C]O), 1475, 1366, 1340, 1275,
1247, 1209, 1090, 1043, 958, 924, 873, 788, 757. EI-MS, m/z (%): 498
(Mþ, 4), 442 (28), 386 (23), 354 (13), 269 (8), 213 (35),173 (100), 148
(8), 138 (9), 101 (11), 89 (12), 57 (27). Anal. Calcd for C26H30N2O8
(498.53): C, 62.64; H, 6.07; N, 5.62. Found: C, 62.5; H, 6.2; N, 5.5%.
1H NMR (500.1 MHz, CDCl3):
d
7.68 (1H, s, CH), 7.49 (1H, td, J¼2.0,
8.1 Hz, CH), 7.38 (1H, dd, J¼8.1, 1.0 Hz, CH), 7.25e7.19 (2H, m, 2CH),
4. Experimental
4.1. General
6.84 (1H, s, NH), 3.80 and 3.63 (6H, 2s, 2OCH3), 1.49 and 1.43 [18H,
2s, 2C(CH3)3]. 13C NMR (125.8 MHz, CDCl3):
d 166.0, 164.9, 162.9,
159.5, 157.2, and 153.9 (4C]O and 2NOC]C), 140.3 (CH), 137.9 (C),
132.3 and 128.2 (2CH), 126.4 (C), 124.6 (CH), 118.1 (C), 116.8 (CH),
115.2 (C), 85.7 (NOC]C), 61.8 and 52.7 [2C(CH3)3], 52.1 and 51.0
(2OCH3), 29.7 and 27.9 [2C(CH3)3].
Dimethyl- and diethyl-acetylenedicarboxylates, tert-butyl- and
cyclohexyl-isocyanides, salicylaldehyde, 2-hydroxy-3-methox-
ybenzaldehyde, 4-(diethylamino)-2-hydroxybenzaldehyde and 1-
hydroxy-2-naphthaldehyde, and Meldrum’s acid were obtained
from Merck (Germany) and Fluka (Switzerland) and were used
without further purification. Melting points were measured on an
Electrothermal 9100 apparatus. Elemental analyses for C, H and N
were performed using a Heraeus CHNeOeRapid analyzer. Mass
spectra were recorded on a FINNIGAN-MATT 8430 mass spec-
trometer operating at an ionization potential of 20 eV 1H and 13C
NMR spectra were measured (CDCl3 solution) with Bruker DRX-500
AVANCE (at 500.1 and 125.8 MHz), Bruker DRX-300 (at 300.1 and
75.5 MHz), and Bruker DPX-250 (at 250.1 and 62.9 MHz) spec-
trometers with TMS as an internal standard. IR spectra were
recorded on a Shimadzu IR-460 spectrometer. Chromatography
columns were prepared from Merck silica gel 230e240 mesh.
4.2.2. Dimethyl 2-(cyclohexylamino)-5-{cyclohexyl[(2-oxo-2H-chro-
men-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5b). Pale yellow
crystals, mp 171e172 ꢀC, yield: 0.468 g, 85%. IR (KBr) (nmax/cmꢂ1):
3344 (NH), 1721, 1656, and 1605 (C]O), 1469, 1447, 1369, 1354,
1274, 1225, 1093, 1050, 972, 930, 888, 725, 680. EI-MS, m/z (%): 550
(Mþ, 36), 519 (12), 468 (9), 410 (15), 377 (56), 295 (100), 197 (12),
173 (89), 83 (37), 55 (69). Anal. Calcd for C30H34N2O8 (550.61) C,
65.44; H, 6.22; N, 5.09. Found: C, 65.4; H, 6.4; N, 4.9%. 1H NMR
(500.1 MHz, CDCl3):
d
7.87 (1H, s, CH), 7.51 (1H, t, J¼7.6 Hz, CH), 7.42
(1H, d, J¼7.5 Hz, CH), 7.26e7.23 (2H, m, 2CH), 6.58 (1H, d, J¼7.6 Hz,
NH), 4.50e4.43 (1H, m, NCH), 3.69 and 3.64 (6H, 2s, 2OCH3),
3.63e3.55 (1H, m, NCH), 1.98e1.02 [20H, m, 2CH(CH2)5]. 13C NMR
(125.8 MHz, CDCl3):
d 165.3, 164.7, 162.8, 159.7, 157.1, and 154.1
(4C]O and 2NOC]C), 142.6 (CH), 136.7 (C), 132.6 and 128.5 (2CH),
125.0 (C), 124.6 (CH), 118.1 (C), 116.8 (CH), 114.8 (C), 85.3 (NOC]C),
55.9 (NCH), 52.0 (OCH3), 51.6 (NCH), 51.0 (OCH3), 33.4 (CH2), 31.6
and 30.2 (2br, 2CH2), 25.7, 25.4, 25.3, and 24.4 (4CH2).
4.2. General procedure for the preparation of compound
5aej, exemplified with 5a
A mixture of salicylaldehyde (0.122 g, 1 mmol) and Meldrum’s
acid (0.144 g, 1 mmol) in H2O (5 mL) was magnetically stirred at
25 ꢀC for 20 min. After nearly complete conversion to coumarin-3-
4.2.3. Diethyl 2-(cyclohexylamino)-5-{cyclohexyl[(2-oxo-2H-chro-
men-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5c). Pale yellow

M. Adib et al. / Tetrahedron 66 (2010) 9263e9269
9267
crystals, mp 170e171 ꢀC, yield: 0.515 g, 89%. IR (KBr) (nmax/cmꢂ1):
3346 (NH), 1734, 1703, 1646, 1604 (C]O), 1469, 1416, 1361, 1320,
1285, 1225, 1155, 1096, 1062, 928, 894, 858, 750, 711. EI-MS, m/z (%):
578 (Mþ, 54), 496 (9), 450 (8), 423 (13), 405 (35), 377 (24), 323
(100), 295 (31), 173 (97), 83 (32), 67 (42), 55 (84). Anal. Calcd for
C32H38N2O8 (578.66): C, 66.42; H, 6.62; N, 4.84. Found: C, 66.4; H,
t, J¼7.7 Hz, CH), 7.08 (1H, d, J¼7.9 Hz, CH), 7.02 (1H, d, J¼7.6 Hz, CH),
6.59 (1H, d, J¼7.4 Hz, NH), 4.50e4.30 (1H, m, NCH), 4.25e4.00 (4H,
m, 2OCH2), 3.93 (3H, s, OCH3), 3.55e3.49 (1H, m, NCH), 2.00e1.05
[6H, 2t (1.21 and 1.17), J¼7.1 Hz, 2OCH2CH3; and 20H, m, 2CH
(CH2)5]. 13C NMR (75.5 MHz, CDCl3):
d 165.4, 164.4, 162.7, 159.6,
156.5, 147.0, and 143.8 (4C]O, CeO, and 2NOC]C), 143.2 (CH),
136.3 and 125.3 (C), 124.4 and 119.8 (2CH), 118.8 and 115.0 (2C),
114.3 (CH), 85.4 (NOC]C), 61.3 and 59.6 (2OCH2), 56.9 (NCH), 56.2
(OCH3), 51.4 (NCH), 33.4 (CH2), 31.8 and 30.4 (2br, 2CH2), 25.6, 25.4,
and 24.4 (3CH2), 14.3 and 14.0 (2CH3).
6.6; N, 4.8%. 1H NMR (500.1 MHz, CDCl3):
d 7.94 (1H, s, CH), 7.54 (1H,
dd, J¼8.1,1.5 Hz, CH), 7.45 (1H, d, J¼8.1 Hz, CH), 7.27 (1H, d, J¼8.1 Hz,
CH), 7.26 (1H, t, J¼7.5 Hz, CH), 6.60 (1H, d, J¼7.8 Hz, NH), 4.49e4.42
(1H, m, NCH), 4.30e4.00 (4H, m, 2OCH2), 3.62e3.57 (1H, m, NCH),
2.11e1.01 [6H, 2t (1.22 and 1.19), J¼7.1 Hz, 2CH2CH3; and 20H, m,
2CH(CH2)5]. 13C NMR (125.8 MHz, CDCl3):
d
165.4, 164.4, 162.8,
4.2.7. Dimethyl 2-(tert-butylamino)-5-(tert-butyl{[7-(diethylamino)-
2-oxo-2H-chromen-3-yl]carbonyl}amino)-3,4-furandicarboxylate
(5g). Pale yellow crystals, mp 204e205 ꢀC, yield: 0.513 g, 90%. IR
(KBr) (nmax/cmꢂ1): 3348 (NH), 1726, 1674, and 16.44 (C]O), 1589,
1513, 1478, 1418, 1348, 1210, 1131, 1090, 1046, 952, 885, 840, 778. EI-
MS, m/z (%): 569 (Mþ, 7), 513 (18), 269 (18), 244 (100), 213 (10), 160
(6), 57 (10). Anal. Calcd for C30H39N3O8 (569.66): C, 63.25; H, 6.90;
N, 7.38. Found: C, 63.3; H, 6.9; N, 7.3%. 1H NMR (300.1 MHz, CDCl3):
159.7, 157.2, and 154.1 (4C]O and 2NOC]C), 142.7 (CH), 136.2 (C),
132.5 and 128.5 (2CH), 125.1 (C), 124.6 (CH), 118.3 (C), 116.8 (CH),
115.2 (C), 85.5 (NOC]C), 61.3 and 59.7 (2OCH2), 57.0 and 51.5
(2NCH), 33.4 (CH2), 31.5 and 30.4 (2br, 2CH2), 25.7, 25.5, 25.4, and
24.4 (4CH2), 14.3 and 14.0 (2CH3).
4.2.4. Dimethyl 2-(cyclohexylamino)-5-{cyclohexyl[(8-methoxy-2-
oxo-2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylate
(5d). Pale yellow crystals, mp 190 ꢀC, yield: 0.511 g, 88%. IR (KBr)
d
7.56 (1H, s, CH), 7.14 (1H, d, J¼8.7 Hz, CH), 6.89 (1H, s, NH), 6.51
(1H, d, J¼8.7 Hz, CH), 6.40 (1H, s, CH), 3.82 and 3.67 (6H, 2s, 2OCH3),
3.39 [4H, q, J¼7.1 Hz, N(CH2CH3)2],1.49 and 1.45 [18H, 2s, 2C(CH3)3],
1.19 [6H, t, J¼7.1 Hz, N(CH2CH3)2]. 13C NMR (75.5 MHz, CDCl3):
(
nmax/cmꢂ1): 3345 (NH), 1724, 1651, and 1606 (C]O), 1473, 1443,
1364, 1325, 1228, 1147, 1099, 1055, 976, 932, 887, 843, 784, 730, 687.
EI-MS, m/z (%): 580 (Mþ, 28), 513 (5), 439 (8), 407 (16), 367 (9), 325
(18), 231 (12), 97 (16), 82 (47), 67 (100), 58 (97). Anal. Calcd for
C31H36N2O9 (580.63): C, 64.13; H, 6.25; N, 4.82. Found: C, 64.3; H,
d
167.3, 165.2, 162.9, 159.5, 158.3, 156.8, and 151.2 (4C]O, C, and
2NOC]C), 141.5 (CH), 139.0 (C), 129.3 (CH), 118.6 and 114.2 (2C),
108.9 (CH), 107.2 (C), 97.2 (CH), 85.7 (NOC]C), 61.4 and 52.6 [2C
(CH3)3], 52.0 and 51.0 (2OCH3), 44.8 [N(CH2CH3)2], 29.8 and 28.0
[2C(CH3)3], 12.4 [N(CH2CH3)2].
6.3; N, 4.7%. 1H NMR (500.1 MHz, CDCl3):
d 7.86 (1H, s, CH), 7.18 (1H,
dd, J¼8.1, 7.9 Hz, CH), 7.07 (1H, d, J¼8.1 Hz, CH), 7.00 (1H, d,
J¼7.9 Hz, CH), 6.60 (1H, d, J¼7.8 Hz, NH), 4.52e4.44 (1H, m, NCH),
3.94, 3.71, and 3.66 (9H, 3s, 3OCH3), 3.63e3.55 (1H, m, NCH),
2.04e1.27 [20H, m, 2CH(CH2)5]. 13C NMR (125.8 MHz, CDCl3):
4.2.8. Dimethyl 2-(cyclohexylamino)-5-(cyclohexyl{[7-(diethylamino)-
2-oxo-2H-chromen-3-yl]carbonyl}amino)-3,4-furandicarboxylate
(5h). Pale yellow crystals, mp 208e209 ꢀC, yield: 0.571 g, 92%. IR
(KBr) (nmax/cmꢂ1): 3310 (NH), 1727, 1678, and 1624 (C]O), 1585,
1511, 1445, 1351, 1232, 1134, 1075, 891, 778, 711, 663. EI-MS, m/z (%):
621 (Mþ,19), 496 (3), 377 (13), 295 (31), 244 (83), 213 (8),181 (10), 97
(13), 82 (58), 67 (100), 54 (76). Anal. Calcd for C34H43N3O8 (621.73): C,
65.68; H, 6.97; N, 6.76. Found: C, 65.6; H, 7.1; N, 6.6%. 1H NMR
d
165.4, 164.7, 162.8, 159.7, 156.5, 147.1, and 143.9 (4C]O, CeO, and
2NOC]C), 143.0 (CH), 136.9 and 125.4 (2C), 124.4 and 119.8 (2CH),
118.8 and 114.7 (2C),114.5 (CH), 85.2 (NOC]C), 57.0 (NCH), 56.3 and
52.0 (2OCH3), 51.5 (NCH), 51.0 (OCH3), 33.5 (CH2), 31.6 and 30.1
(2br, 2CH2), 25.7, 25.5, 25.4, and 24.5 (4CH2).
4.2.5. Diethyl 2-(tert-butylamino)-5-{tert-butyl[(8-methoxy-2-oxo-
2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5e). Pale
yellow crystals, mp 207e208 ꢀC, yield: 0.473 g, 85%. IR (KBr)
(500.1 MHz, CDCl3):
d
7.75 (1H, s, CH), 7.18 (1H, d, J¼8.9 Hz, CH), 6.63
(1H, d, J¼7.9 Hz, NH), 6.53 (1H, dd, J¼8.9, 2.4 Hz, CH,), 6.41 (1H, d,
J¼2.4 Hz, CH), 4.53e4.48 (1H, m, NCH), 3.69 and 3.67 (6H, 2s, 2OCH3),
3.66e3.59 (1H, m, NCH), 3.40 [4H, q, J¼7.1 Hz, N(CH2CH3)2],
2.06e1.03 {[6H, t (1.20), J¼7.1 Hz, N(CH2CH3)2]; and 20H, m, 2CH
(
nmax/cmꢂ1): 3325 (NH), 1730, 1685, 1652, 1615 (C]O), 1573, 1508,
1486, 1450, 1414, 1355, 1277, 1231, 1126, 1094, 893, 750, 712. EI-MS,
m/z (%): 556 (Mþ, 9), 500 (25), 444 (16), 398 (20), 297 (9), 210 (8),
203 (100), 89 (8), 57 (38). Anal. Calcd for C29H36N2O9 (556.61): C,
62.58; H, 6.52; N, 5.03. Found: C, 62.6; H, 6.5; N, 5.0%. 1H NMR
(CH2)5}. 13C NMR (125.8 MHz, CDCl3):
d 166.5, 165.0, 162.8, 159.7,
158.3, 157.1, and 151.6 (4C]O, C, and 2NOC]C), 143.9 (CH), 138.1 (C),
129.7 (CH), 116.9 and 113.8 (2C), 109.0 (CH), 107.6 (C), 97.2 (CH), 85.2
(NOC]C), 56.8 (NCH), 51.9 (OCH3), 51.5 (NCH), 50.9 (OCH3), 44.9 [N
(CH2CH3)2], 33.5 (CH2), 31.6 and 30.4 (2br, 2CH2), 25.8, 25.5, and 24.5
(3CH2), 12.5 [N(CH2CH3)2].
(250.1 MHz, CDCl3):
d
7.72 (1H, s, CH), 7.17 (1H, dd, J¼8.0, 7.7 Hz,
CH), 7.05 (1H, dd, J¼8.0, 1.2 Hz, CH), 6.97 (1H, dd, J¼7.5, 1.3 Hz, CH),
6.84 (1H, br s, NH), 4.34 and 4.19 (2H, 2dq, ABX3 system, 2J¼10.8 Hz
and 3J¼7.0 Hz, OCHAHBCH3), 4.17 and 4.08 (2H, 2dq, ABX3 system,
2J¼10.8 Hz and 3J¼7.0 Hz, OCHAHBCH3), 3.93 (3H, s, OCH3), 1.51 and
4.2.9. Diethyl 2-(cyclohexylamino)-5-(cyclohexyl{[7-(diethylamino)-
2-oxo-2H-chromen-3-yl]carbonyl}amino)-3,4-furandicarboxylate
(5i). Pale yellow crystals, mp 202e203 ꢀC, yield: 0.624 g, 96%. IR
(KBr) (nmax/cmꢂ1): 3366 (NH), 1713 and 1642 (C]O), 1593, 1515,
1459,1416,1356,1231,1136,1067, 891, 826, 781, 709. EI-MS, m/z (%):
649 (Mþ, 13), 405 (19), 368 (9), 323 (40), 295 (12), 244 (80), 82 (48),
67 (100), 54 (65). Anal. Calcd for C36H47N3O8 (649.78): C, 66.54; H,
7.29; N, 6.47. Found: C, 66.5; H, 7.2; N, 6.5%. 1H NMR (500.1 MHz,
1.44 [18H, 2s, 2C(CH3)3], 1.30 and 1.22 (6H, 2t, J¼7.0 Hz, 2CH3). 13
C
NMR (62.9 MHz, CDCl3): d 166.1, 164.6, 162.8, 159.4, 156.7, 147.1, and
143.6 (4C]O, CeO, and 2NOC]C), 140.6 (CH), 137.3 and 126.6 (2C),
124.4 and 119.6 (2CH),118.7 (C),115.3 (C),114.1 (CH), 85.9 (NOC]C),
61.7 [C(CH3)3], 61.4 and 59.7 (2OCH2), 56.2 (OCH3), 52.6 [C(CH3)3],
29.7 and 27.9 [2C(CH3)3], 14.3 and 14.1 (2CH3).
4.2.6. Diethyl 2-(cyclohexylamino)-5-{cyclohexyl[(8-methoxy-2-oxo-
2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5f). Pale
yellow crystals, mp 186e187 ꢀC, yield: 0.529 g, 87%. IR (KBr)
CDCl3):
d
8.00 (1H, s, CH), 7.19 (1H, d, J¼8.9 Hz, CH), 6.59 (1H, d,
J¼8.0 Hz, NH), 6.52 (1H, dd, J¼8.9, 2.4 Hz, CH), 6.39 (1H, d, J¼2.4 Hz,
CH), 4.44e4.37 (1H, m, NCH), 4.24e3.97 (4H, m, 2OCH2), 3.65e3.55
(1H, m, NCH), 3.38 [4H, q, J¼7.1 Hz, N(CH2CH3)2], 2.05e1.02 {[3H, t
(1.21), J¼7.2 Hz, OCH2CH3]; [6H, t (1.18), J¼7.1 Hz, N(CH2CH3)2]; [3H,
t (1.15), J¼7.1 Hz, OCH2CH3]; and 20H, m, 2CH(CH2)5}. 13C NMR
(
nmax/cmꢂ1): 3350 (NH), 1723, 1643, and 16.09 (C]O), 1473, 1359,
1319, 1224, 1097, 1062, 973, 928, 884, 780, 730, 693. EI-MS, m/z (%):
608 (Mþ, 9), 405 (16), 368 (8), 323 (43), 249 (27), 220 (20), 203 (50),
167 (19), 140 (22), 83 (32), 57 (66), 45 (100). Anal. Calcd for
C33H40N2O9 (608.69): C, 65.12; H, 6.62; N, 4.60. Found: C, 64.9; H,
(125.8 MHz, CDCl3):
d 166.5, 164.6, 162.8, 159.6, 158.2, 157.1, and
151.5 (4C]O, C, and 2NOC]C), 144.0 (CH), 137.5 (C), 129.7 (CH),
117.0 and 114.2 (2C), 109.0 (CH), 107.6 (C), 97.2 (CH), 85.5 (NOC]C),
6.7; N, 4.8%. 1H NMR (300.1 MHz, CDCl3):
d 7.92 (1H, s, CH), 7.17 (1H,

9268
M. Adib et al. / Tetrahedron 66 (2010) 9263e9269
61.1 and 59.5 (2OCH2), 56.8 and 51.4 (2NCH), 44.9 [N(CH2CH3)2],
33.5 (CH2), 31.7 and 30.4 (2br, 2CH2), 25.8, 25.5, and 24.5 (3CH2),
14.3 and 14.0 (2OCH2CH3), 12.4 [N(CH2CH3)2].
125.0 and 120.2 (2CH), 118.3 (C), 115.4 (CH), 60.5 (NCH), 56.4, 53.0,
and 52.5 (3OCH3), 29.1, 26.5, and 25.2 (3CH2).
4.4. Procedure for the preparation of compound 5k
4.2.10. Dimethyl 2-(cyclohexylamino)-5-{cyclohexyl[(2-oxo-2H-benzo
[h]chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylate (5j). Pale
yellow crystals, mp 222 ꢀC, yield: 0.498 g, 83%. IR (KBr) (nmax/cmꢂ1):
3367 (NH), 1729 and 16.62 (C]O), 1596, 1516, 1444, 1393, 1360,
1313, 1214, 1147, 1096, 1070, 923, 819, 783, 749, 717, 679. EI-MS, m/z
(%): 600 (Mþ, 12), 377 (47), 295 (100), 223 (65), 263 (5), 181 (35),
139 (37), 83 (16), 55 (41). Anal. Calcd for C34H36N2O8 (600.67): C,
67.99; H, 6.04; N, 4.66. Found: C, 68.2; H, 6.3; N, 4.4%. 1H NMR
A mixture of 12b (0.236 g, 0.5 mmol) and tert-butyl isocyanide
(0.041 g, 0.5 mmol) in H2O (3 mL) was magnetically stirred at 25 ꢀC
for 5 h. Next, the aqueous phase was extracted with CH2Cl2
(2ꢁ5 mL) and the combined organic layers dried over magnesium
sulfate. The solvent was evaporated and the residue was purified by
column chromatography using n-hexaneeEtOAc (3:1) as eluent.
The solvent was removed and the product was obtained.
(300.1 MHz, CDCl3):
d
8.70 (1H, s, CH), 8.22 (1H, d, J¼8.4 Hz, CH),
8.01 (1H, d, J¼9.0 Hz, CH), 7.91 (1H, d, J¼8.0 Hz, CH), 7.69 (1H, dd,
J¼7.7, 7.2 Hz, CH), 7.58 (1H, dd, J¼7.7, 7.2 Hz, CH), 7.41 (1H, d,
J¼9.0 Hz, CH), 6.60 (1H, d, J¼7.9 Hz, NH), 4.59e4.50 (1H, m, NCH),
3.69e3.60 [6H, 2s (3.68 and 3.62), 2OCH3; and 1H, m, NCH],
4.4.1. Dimethyl
2-(tert-butylamino)-5-{cyclohexyl[(8-methoxy-2-
oxo-2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylate
(5k). Pale yellow crystals, mp 218 ꢀC, yield: 0.244 g, 88%. IR (KBr)
(
nmax/cmꢂ1): 3313 (NH), 1721, 16.78, 1638, 1603 (C]O), 1472, 1441,
2.15e1.10 [20H, m, 2CH(CH2)5]. 13C NMR (75.5 MHz, CDCl3):
d 165.7,
1402, 1362, 1323, 1253, 1215, 1065, 973, 882, 776, 728, 688. EI-MS,
m/z (%): 554 (Mþ, 20), 416 (7), 351 (50), 295 (9), 269 (50), 256 (12),
213 (100), 203 (98), 181 (43), 138 (16), 55 (32). Anal. Calcd for
C29H34N2O9 (554.60): C, 62.81; H, 6.18; N, 5.05. Found: C, 62.8; H,
164.7, 162.9, 159.7, 157.3, and 154.3 (4C]O and 2NOC]C), 138.8
(CH), 136.9 (C), 134.1 (CH), 130.3 and 129.3 (2C), 129.0, 128.5, and
126.2 (3CH), 123.6 (C), 121.3 and 116.7 (2CH), 114.7 and 112.4 (2C),
85.2 (NOC]C), 57.0 (NCH), 52.1 (OCH3), 51.6 (NCH), 50.9 (OCH3),
33.6, 33.5, 31.6, and 30.3 (4br, 4CH2), 25.7 (CH2), 25.4 (br, CH2),
24.5 (CH2).
6.2; N, 5.0%. 1H NMR (250.1 MHz, CDCl3):
d 7.85 (1H, s, CH), 7.19 (1H,
dd, J¼8.0, 7.5 Hz, CH), 7.07 (1H, d, J¼7.5 Hz, CH), 7.00 (1H, d,
J¼8.0 Hz, CH), 6.92 (1H, s, NH), 4.53e4.44 (1H, m, NCH), 3.93, 3.73,
and 3.66 (9H, 3s, 3OCH3), 2.17e1.01 [9H, s, C(CH3)3; and 10H, m, CH
(CH2)5]. 13C NMR (62.9 MHz, CDCl3):
d 165.4, 164.9, 162.8, 159.9,
4.3. General procedure for the preparation of compound 12a
and 12b, exemplified with 12a
156.5, 147.0, and 143.7 (4C]O, CeO, and 2NOC]C), 142.8 (CH),
136.8 and 125.2 (2C), 124.4 and 119.7 (2CH), 118.6 and 114.5 (2C),
114.4 (CH), 85.7 (NOC]C), 56.7 [C(CH3)3], 56.2 (OCH3), 52.7 (NCH),
52.1 and 51.0 (2OCH3), 31.7 and 30.0 (2CH2), 29.8 [C(CH3)3], 25.8,
25.5, and 25.3 (3CH2).
A mixture of salicylaldehyde (0.122 g, 1 mmol) and Meldrum’s
acid (0.144 g, 1 mmol) in H2O (5 mL) was magnetically stirred at
25 ꢀC for 20 min. After nearly complete conversion to coumarin-3-
carboxylic acid, cycloyl isocyanide (0.109 g, 1 mmol) was added to
the reaction mixture. Then diethyl acetylenedicarboxylate (0.170 g,
1 mmol) was added at room temperature over 5 min. The reaction
mixture was then allowed to stir for 5 h. Next, the aqueous phase
was extracted with CH2Cl2 (3ꢁ5 mL) and the combined organic
layers dried over magnesium sulfate. The solvent was evaporated
and the residue was purified by column chromatography using n-
hexaneeEtOAc (3:1) as eluent. The solvent was removed and the
product was obtained.
Acknowledgements
This research was supported by the Research Council of the
University of Tehran as a research project (6102036/1/03).
Supplementary data
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2010.09.032.
4.3.1. Diethyl 2-({cyclohexyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}
carbonyl)-2-butenedioate (12a). Pale yellow crystals, mp 166e167 ꢀC,
yield: 0.34 g, 73%. Anal. Calcd for C25H27NO8 (469.49): C, 63.96; H,
5.80; N, 2.98. Found: C, 63.8; H, 5.9; N, 2.8%. 1H NMR (500.1 MHz,
References and notes
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d
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7.8 Hz, CH), 7.15 (1H, d, J¼8.1 Hz, CH), 7.09 (1H, d, J¼7.8 Hz, CH), 6.64
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