Isocyanide-based three-component synthesis of functionalized 5-alkylimino-2,5-dihydrofuran-3,4-dicarboxylate and their conversion to substituted furanones

Article abstract of DOI:10.1002/jhet.633

The zwitterionic 1:1 intermediates formed from alkyl isocyanides and acetylenic esters are trapped by alkyl bromides to form 5-alkylimino-2,5- dihydrofuran-3,4-dicarboxylate in relatively good yields at room temperature under solventless conditions. Hydro

Full text of DOI:10.1002/jhet.633

626
Isocyanide-Based Three-Component Synthesis of Functionalized
5-Alkylimino-2,5-dihydrofuran-3,4-dicarboxylate and Their
Conversion to Substituted Furanones
Vol 48
Zinatossadat Hossaini,a* Hosein Hamadi,b Faramarz Rostami Charati,c
Mehdi Khoobi,d and Abbas Shafieee
aDepartment of Chemistry, Islamic Azad University, Qaemshahr Branch, 163 Mazandaran, Iran
bDepartment of Chemistry, Tarbiat Modares University, Tehran, Iran
cFaculty of Science, Gonbad Higher Education Center, Gonbad, Iran
dDepartment of Chemistry, Zanjan University, Zanjan, Iran
eDepartment of Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center,
Tehran University of Medical Sciences, Tehran 14174, Iran
*E-mail: zshossaini@yahoo.com
Received June 12, 2010
DOI 10.1002/jhet.633
Published online 15 March 2011 in Wiley Online Library (wileyonlinelibrary.com).
The zwitterionic 1:1 intermediates formed from alkyl isocyanides and acetylenic esters are trapped by
alkyl bromides to form 5-alkylimino-2,5-dihydrofuran-3,4-dicarboxylate in relatively good yields at
room temperature under solventless conditions. Hydrolysis of these compounds by HCl (5%) produced
substituted furanones.
J. Heterocyclic Chem., 48, 626 (2011).
INTRODUCTION
structural feature readily for further elaboration is still
of current interest. Not surprisingly, a great degree of
synthetic efforts have been devoted for developing ver-
satile and efficient route to furanones [23].
Furans and their derivatives play an important role in
organic chemistry because of their presence as key
structural units in many natural products and pharma-
ceuticals, and as essential building blocks for the total
synthesis of complex naturally occurring compounds.
Furthermore, polyfunctionalized furans are versatile syn-
thetic starting materials for the preparation of a variety
of heterocyclic and acyclic compounds [1–9]. Espe-
cially, 2,5-disubstituted furan-3,4-dicarboxylates are
very important starting materials in the synthesis of nat-
ural products containing tetrahydrofuran rings [10]. So
far, many synthetic protocols for the synthesis of imino-
lactones have been reported. The most widely used
approach to iminolactones synthesis is the isocyanide-
based reactions [11–18].
As part of an ongoing development of efficient proto-
cols for the preparation of biologically active hetero-
cycles from common intermediates [24–26], we report
the synthesis of iminolactones 4 via the three-component
condensation of isocyanides 1, dialkyl acetylenedicar-
boxylates 2, and phenacyl bromide or its derivatives 3
in solvent-free conditions at ambient temperature
(Scheme 1). Hydrolysis of 5-alkylimino-2,5-dihydro-
furan-3,4-dicarboxylates 4 with aqueous HCl (5%) in
dichloromethane afforded butenolides 5 (see Table 1).
RESULT AND DISCUSSION
Furanones, a unit occurring in a large number of natu-
ral products [19], have caught the attention of both or-
ganic and bioorganic chemists because many of the
butenolide-containing compounds may be considered as
potential insecticides, bactericides, fungicides, phospho-
liphase A2 inhibitors, etc [20,21]. Furanones are also
versatile building blocks for the synthesis of a wide va-
riety of biologically active compounds and complex nat-
ural products [22]. Despite these achievements, the de-
velopment of efficient synthetic methods leading to
the formation of this class of compounds with a new
As indicated in Scheme 1, the 1:1:1 addition reaction
of isocyanides 1 with dialkyl acetylenedicarboxylates 2
and alkyl bromide or its derivatives 3 occurs smoothly
at room temperature to produce 5-alkylimino-2,5-dihy-
drofuran-3,4-dicarboxylate 4. Hydrolysis of 4 with aque-
ous HCl (5%) in dichloromethane afforded furanones 5.
The structures of the products were deduced from
1
their Infrared (IR), mass, H-NMR, and 13C-NMR spec-
tra. The mass spectra of these compounds displayed mo-
1
lecular ion peaks at the appropriate m/z values. The H-
C
V
2011 HeteroCorporation

May 2011
Isocyanide-Based Three-Component Synthesis of Functionalized 5-Alkylimino-
2,5-dihydrofuran-3,4-dicarboxylate and Their Conversion to Substituted Furanones
627
Scheme 1
NMR spectrum of 4a in CDCl3 showed a singlet at d ¼
1.39 for tert-butyl group and a singlet at 2.36 for the
methyl group. The methylene protons of CH2Br are dia-
ionic intermediate 6 produced by reaction between the
isocyanide and the dialkyl acetylenedicarboxylate adds
to phenacyl bromide 3 resulting in the formation of 7,
which undergoes cyclization to give the 5-alkylimino-
2,5-dihydrofuran-3,4-dicarboxylate 4. Hydrolysis of 5-
2
stereotopic and showed two doublet at d ¼ 4.12 (d, J
2
¼ 11.0 Hz) and 4.52 (d, J ¼ 11.0 Hz). Two peaks at d
¼ 160.9 and 162.3 are observed in the 13C-NMR spec-
alkylimino-2,5-dihydrofuran-3,4-dicarboxylate
4
with
trum of 4a, which are attributed to the carbonyl groups.
aqueous HCl (5%) in dichloromethane afforded buteno-
lides 5.
1
The H- and 13C-NMR spectra of 4b–4x are similar to
those for 4a except for the imino or aromatic moieties
and the substituents in position 4, which show character-
istic resonances in appropriate regions of the spectrum.
To explore the scope of this reaction further, we
extended our studies to the reaction of various dialkyl
acetylenedicarboxylates and isocyanides with alkyl bro-
mide. As indicated in Table 1, the reactions proceeded
very efficiently in excellent yields. Although the mecha-
nism of this reaction has not been established, a plausi-
ble rationalization can be advanced to explain product
formation (Scheme 2).
In conclusion, a facile one-pot method for the synthe-
sis of 5-alkylimino-2,5-dihydrofuran-3,4-dicarboxylate
derivatives from readily accessible precursors has been
proceed. These compounds are important starting mate-
rials in the synthesis of natural products containing tet-
rahydrofuran rings [10]. Hydrolysis of these compounds
with HCl (5%) produced furanones in dichloromethane
as the solvent. The advantages of our work are as fol-
lows: (1) the reaction is performed under neutral and
mild conditions, (2) no catalyst is required for this reac-
tion, and (3) the simplicity of the present procedure
makes it an interesting alternative to the complex multi-
step approaches.
On the basis of the well-established chemistry of iso-
cyanides [27–31], it is reasonable to assume that zwitter-
Table 1
Synthesis of 5-alkylimino-2,5-dihydro-3,4-furandicarboxylates and furanones.
Entry
R
R0
Ar
Compound 4
Yield of 4 (%)
Compound 5
Yield of 5 (%)
1
2
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
tert-Butyl
tert-Butyl
Me
Et
4-MeAC6H4
4-MeAC6H4
4-NO2AC6H4
4-NO2AC6H4
4-PhAC6H4
4-PhAC6H4
4-ClAC6H4
4-ClAC6H4
4-OMeAC6H4
4-OMeAC6H4
4-OMeAC6H4
4-OMeAC6H4
4-MeAC6H4
4-MeAC6H4
4-NO2AC6H4
4-NO2AC6H4
4-PhAC6H4
4-PhAC6H4
4-ClAC6H4
4-ClAC6H4
Naphthyl
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
4s
85
84
85
87
83
80
84
82
87
83
90
92
85
92
87
90
85
86
87
85
85
87
84
85
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
5s
82
80
82
85
80
76
82
80
85
78
86
80
83
82
80
85
82
78
84
80
83
85
82
84
3
4
Me
Et
5
6
Me
Et
7
Me
Et
Me
Et
Me
Et
Me
Et
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Me
Et
Me
Et
Me
Et
4t
5t
Me
Et
Me
Et
4u
4v
4w
4x
5u
5v
5w
5x
Naphthyl
Naphthyl
Naphthyl
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

628
Z. Hossaini, H. Hamadi, F. R. Charati, M. Khoobi, and A. Shafiee
Vol 48
Scheme 2
Me3C), 3.79 (3 H, s, MeO), 3.90 (3 H, s, MeO), 4.16 (1 H, d,
2
2J ¼ 11.2 Hz, CH), 4.44 (1 H, d, J ¼ 11.2 Hz, CH), 7.68 (2
3
3
H, d, J ¼ 8.5 Hz, 2 CH), 8.23 (2 H, d, J ¼ 8.5 Hz, 2 CH).
13C-NMR: d ¼ 29.5 (Me3C), 35.8 (CH2Br), 53.1 (MeO), 53.4
(MeO), 55.2 (Me3C), 89.9 (C), 123.8 (2 CH), 127.4 (2 CH),
139.5 (C), 140.6 (C), 143.7 (C), 148.0 (C), 151.0 (C¼¼N),
160.7 (C¼¼O), 161.9 (C¼¼O). Anal Calcd for C19H21BrN2O5
(469.29): C, 48.63; H, 4.51; N, 5.97; found: C, 48.80; H, 4.32;
N, 5.75.
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-nitrophenyl)-
2,5-dihydrofuran-3,4-dicarboxylate (4d). Orange powder, yield:
0.86 g (87%), m.p. 158–160ꢀC. IR (KBr) (mmax/cmꢁ1): 1743,
EXPERIMENTAL
Melting points were taken on a Kofler hot stage apparatus and
are uncorrected. 1H-NMR and 13C-NMR spectra were obtained
with a Bruker FT-500 spectrometer in CDCl3, and tetramethylsi-
lane was used as an internal standard. Mass spectra were
recorded with a Finnigan Mat TSQ-70 spectrometer. IR spectra
were acquired on a Nicollet Magna 550-FT spectrometer. Ele-
mental analyses were carried out with a Perkin-Elmer model
240-C apparatus. The results of elemental analyses (C, H, and
N) were within 60.4% of the calculated values. Acetylenic ester,
phenacyl bromide, or its derivatives and isocyanides were
obtained from Fluka and were used without further purification.
General procedure for the preparation of compounds
4a–4x. A mixture of alkyl bromides (2 mmol) and dialkyl ace-
tylenedicarboxylate (2 mmol) was stirred at room temperature.
To this mixture, isocyanides (2 mmol) was added slowly. The
reaction mixture was stirred for 12 h at room temperature and
purified by short column chromatography (silica gel) using pe-
troleum ether-ethyl acetate as eluent. The product was then
crystallized from hexane to give the desired compound.
1
3
1695, 1664, 1586, 1249 cmꢁ1. H-NMR: d ¼ 1.23 (3 H, t, J
3
¼ 7.2 Hz, Me), 1.34 (3 H, t, J ¼ 7.4 Hz, Me), 1.37 (9 H, s,
2
Me3C), 4.15 (1 H, d, J ¼ 11.5 Hz, CH), 4.23–4.30 (2 H, m,
2
3
OCH2), 4.34 (1 H, d, J ¼ 11.5 Hz, CH), 4.38 (2 H, q, J ¼
3
7.5 Hz, OCH2), 7.67 (2 H, d, J ¼ 8.4 Hz, 2 CH), 8.22 (2 H,
d, J ¼ 8.4 Hz, 2 CH). 13C-NMR: d ¼ 14.0 (Me), 14.5 (Me),
3
30.2 (Me3C), 36.8 (CH2Br), 56.8 (Me3C), 61.4 (OCH2), 62.0
(OCH2), 90.0 (C), 124.8 (2 CH), 128.2 (2 CH), 140.0 (C),
141.4 (C), 143.5 (C), 148.4 (C), 151.9 (C¼¼N), 160.5 (C¼¼O),
161.9 (C¼¼O). Anal Calcd for C21H25BrN2O7: C, 50.72; H,
5.07; N, 5.63; found: C, 50.54; H, 4.86; N, 5.37.
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(p-biphenyl)-
2,5-dihydrofuran-3,4-dicarboxylate
(4e). Yellow
powder,
yield: 0.83 g (83%), m.p. 138–140ꢀC. IR (KBr) (mmax/cmꢁ1):
1720, 1675, 1642, 1583, 1270 cmꢁ1. H-NMR: d ¼ 1.34 (9 H,
1
s, Me3C), 3.82 (3 H, s, MeO), 3.90 (3H, s, MeO), 4.23 (1 H,
2
2
d, J ¼ 11.2 Hz, CH), 4.54 (1 H, d, J ¼ 11.2 Hz, CH), 7.34
3
3
(1 H, t, J ¼ 7.6 Hz, CH), 7.42 (2 H, t, J ¼ 7.6 Hz, 2 CH),
3
3
7.65 (2 H, d, J ¼ 7.6 Hz, 2 CH), 7.67 (2 H, d, J ¼ 8.2 Hz,
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(p-tolyl)-2,5-
dihydrofuran-3,4-dicarboxylate (4a). Yellow crystals, yield:
0.74 g (85%), m.p. 121–123ꢀC. IR (KBr) (mmax/cmꢁ1): 1726,
2 CH), 7.74 (2 H, d, J ¼ 8.2 Hz, 2 CH). 13C-NMR: d ¼ 29.8
3
(Me3C), 38.5 (CH2Br), 52.8 (MeO), 53.0 (MeO), 55.8 (Me3C),
89.0 (C), 127.2 (2 CH), 127.8 (2 CH), 128.0 (2 CH), 128.2
(CH), 129.0 (2 CH), 136.5 (C), 138.0 (C), 141.2 (C), 142.6
(C), 143.2 (C), 159.4 (C¼¼N), 162.0 (C¼¼O), 162.6 (C¼¼O).
Anal Calcd for C25H26BrNO5: C, 60.01; H, 5.24; N, 2.80;
found: C, 60.32; H, 5.42; N, 3.00.
1680, 1652, 1583, 1263 cmꢁ1
.
1H-NMR: d ¼ 1.39 (9 H, s,
Me3C), 2.36 (3 H, s, Me), 3.78 (3 H, s, MeO), 3.90 (3 H, s,
MeO), 4.12 (1 H, d, 2J ¼ 11.0 Hz, CH), 4.52 (1 H, d, 2J ¼
3
11.0 Hz, CH), 7.16 (2 H, d, J ¼ 7.6 Hz, 2 CH), 7.33 (2 H, d,
3J ¼ 7.5 Hz, 2 CH). 13C-NMR: d ¼ 20.9 (Me), 29.5 (Me3C),
36.8 (CH2Br), 52.7 (MeO), 52.8 (MeO), 54.8 (Me3C), 90.5
(C), 125.6 (2 CH), 129.4 (2 CH), 133.8 (C), 138.6 (C), 138.9
(C), 141.9 (C), 152.2 (C¼¼N), 161.0 (C¼¼O), 162.3 (C¼¼O).
Anal Calcd for C20H24BrNO5: C, 54.80; H, 5.52; N, 3.20;
found: C, 54.97; H, 5.74; N, 3.02.
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(p-biphenyl)-
2,5-dihydrofuran-3,4-dicarboxylate (4f). Yellow powder, yield:
0.84 g (80%), m.p. 165–167ꢀC. IR (KBr) (mmax/cmꢁ1): 1725,
1
3
1674, 1650, 1585, 1272 cmꢁ1. H-NMR: d ¼ 1.28 (3 H, t, J ¼
7.5 Hz, Me), 1.35 (3 H, t, 3J ¼ 7.4 Hz, Me), 1.38 (9 H, s,
Me3C), 4.14 (1 H, d, 2J ¼ 11.0 Hz, CH), 4.38–4.42 (2 H, m,
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(p-tolyl)-2,5-
dihydrofuran-3,4-dicarboxylate (4b). Yellow crystals, yield:
0.78 g (84%), m.p. 126–128ꢀC. IR (KBr) (mmax/cmꢁ1): 1725,
3
2
OCH2), 4.45 (2 H, q, J ¼ 7.3 Hz, OCH2), 4.57 (1 H, d, J ¼
3
3
11.0 Hz, CH), 7.37 (1 H, t, J ¼ 7.6 Hz, CH), 7.45 (2 H, t, J ¼
3
1
3
1678, 1662, 1580, 1260 cmꢁ1. H-NMR: d ¼ 1.15 (3 H, t, J ¼
7.3 Hz, Me), 1.27 (3 H, t, 3J ¼ 7.2 Hz, Me), 1.35 (9 H, s, Me3C),
2.34 (3 H, s, Me), 4.10 (1 H, d, 2J ¼ 11.2 Hz, CH), 4.25–4.30 (2
H, m, OCH2), 4.32–4.40 (2 H, q, OCH2), 4.45 (1 H, d, 2J ¼ 11.2
7.5 Hz, 2 CH), 7.50 (2 H, d, J ¼ 7.6 Hz, 2 CH), 7.57 (2 H, d,
3J ¼ 8.4 Hz, 2 CH), 7.61 (2 H, d, J ¼ 8.4 Hz, 2 CH). 13C-
3
NMR: d ¼ 14.0 (Me), 14.2 (Me), 30.4 (Me3C), 36.7 (CH2Br),
56.9 (CAN), 60.2 (OCH2), 61.8 (OCH2), 89.5 (C), 127.0 (2 CH),
127.5 (2 CH), 127.8 (2 CH), 128.0 (CH), 128.9 (2 CH), 136.6
(C), 137.7 (C), 140.4 (C), 142.7 (C), 143.0 (C), 158.6 (C¼¼N),
161.5 (C¼¼O), 162.7 (C¼¼O). MS: m/z (%) ¼ 529 (Mþ þ 2, 15),
527 (Mþ, 15), 514 (94), 468 (78), 314 (36), 181 (100), 152 (48),
57 (72). Anal Calcd for C27H30BrNO5: C, 61.37; H, 5.72; N,
2.65; found: C, 61.24; H, 5.68; N, 2.53.
3
3
Hz, CH), 7.15 (2 H, d, J ¼ 7.5 Hz, 2 CH), 7.37 (2 H, d, J ¼
7.8 Hz, 2 CH). 13C-NMR: d ¼ 13.5 (Me), 14.0 (Me), 21.2 (Me),
29.5 (Me3C), 37.4 (CH2Br), 56.2 (Me3C), 60.37 (OCH2), 61.5
(OCH2), 87.5 (C), 125.2 (2 CH), 128.9 (2 CH), 133.7 (C), 139.0
(C), 139.5 (C), 142.0 (C), 154.2 (C¼¼N), 162.0 (C¼¼O), 162.8
(C¼¼O). Anal Calcd for C22H28BrNO5: C, 56.66; H, 6.05; N,
3.00; found: C, 56.38; H, 5.74; N, 3.30.
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-chloro-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4g). Pale yellow
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-nitrophenyl)-
2,5-dihydrofuran-3,4-dicarboxylate (4c). Yellow powder, yield:
0.80 g (85%), m.p. 157–159ꢀC. IR (KBr) (mmax/cmꢁ1): 1740,
powder, yield: 0.77 g (84%), m.p. 148–150ꢀC. IR (KBr) (mmax
/
cmꢁ1): 1730, 1682, 1638, 1590, 1257 cmꢁ1
.
1H-NMR: d ¼
1681, 1658, 1587, 1254 cmꢁ1
.
1H-NMR: d ¼ 1.39 (9 H, s,
1.38 (9 H, s, Me3C), 3.75 (3 H, s, MeO), 3.92 (3 H, s, MeO),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2011
Isocyanide-Based Three-Component Synthesis of Functionalized 5-Alkylimino-
2,5-dihydrofuran-3,4-dicarboxylate and Their Conversion to Substituted Furanones
629
2
2
4.12 (1 H, d, J ¼ 11.0 Hz, CH), 4.45 (1 H, d, J ¼ 11.0 Hz,
134.6 (C), 138.2 (C), 140.3 (C), 148.9 (C), 156.0 (C¼¼N),
160.9 (C¼¼O), 162.0 (C¼¼O). Anal Calcd for C22H26BrNO6: C,
55.01; H, 5.46; N, 2.92; found: C, 54.72; H, 5.24; N, 2.70.
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-methoxy-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4l). Yellow crys-
3
3
CH), 7.35 (2 H, d, J ¼ 8.0 Hz, 2 CH), 7.42 (2 H, d, J ¼ 7.9
Hz, 2 CH). 13C-NMR: d ¼ 29.8 (Me3C), 38.4 (CH2Br), 52.4
(MeO), 53.4 (MeO), 58.4 (CAN), 90.4 (C), 127.8 (2 CH),
128.4 (2 CH), 136.0 (C), 137.7 (C), 142.8 (C), 148.7 (C),
154.0 (C¼¼N), 161.9 (C¼¼O), 162.4 (C¼¼O). Anal Calcd for
C19H21BrClNO5: C, 49.75; H, 4.61; N, 3.05; found: C, 49.57;
H, 4.40; N, 2.82.
tals, yield: 0.93 g (92%), m.p. 152–154ꢀC. IR (KBr) (mmax
/
cmꢁ1): 1734, 1678, 1664, 1580, 1272 cmꢁ1
.
1H-NMR: d ¼
1.25 (3 H, t, 3J ¼ 7.4 Hz, Me), 1.35 (3 H, t, 3J ¼ 7.3 Hz,
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-chlorophenyl)-
2,5-dihydrofuran-3,4-dicarboxylate (4h). Yellow powder, yield:
0.80 g (82%), m.p. 158–160ꢀC. IR (KBr) (mmax/cmꢁ1): 1727,
Me), 1.45–1.95 (10 H, m, 5 CH2), 3.77 (1 H, m, CH), 3.85 (3
2
H, s, MeO), 4.14 (1 H, d, J ¼ 11.2 Hz, CH), 4.25–4.30 (2 H,
3
2
m, OCH2), 4.34 (2 H, q, J ¼ 7.4 Hz, OCH2), 4.55 (1 H, d, J
1684, 1664, 1584, 1270 cmꢁ1. H-NMR: d ¼ 1.25 (3 H, t, J
1
3
3
¼ 11.2 Hz, CH), 7.12 (2 H, d, J ¼ 8.5 Hz, 2 CH), 7.32 (2 H,
3
d, J ¼ 8.5 Hz, 2 CH). 13C-NMR: d ¼ 13.0 (Me), 14.2 (Me),
3
¼ 7.3 Hz, Me), 1.32 (3 H, t, J ¼ 7.3 Hz, Me), 1.39 (9 H, s,
2
Me3C), 4.18 (1 H, d, J ¼ 11.3 Hz, CH), 4.22–4.28 (2 H, m,
24.5 (2 CH2), 25.4 (CH2), 33.0 (2 CH2), 37.3 (CH2Br), 53.4
(MeO), 57.8 (CAN), 62.4 (OCH2), 62.9 (OCH2), 90.4 (C),
113.2 (2 CH), 127.3 (2 CH), 135.2 (C), 137.8 (C), 141.3 (C),
149.0 (C), 156.4 (C¼¼N), 161.6 (C¼¼O), 162.4 (C¼¼O). Anal
Calcd for C24H30BrNO6: C, 56.70; H, 5.95; N, 2.76; found: C,
56.85; H, 6.12; N, 2.93.
3
2
OCH2), 4.38 (2 H, q, J ¼ 7.5 Hz, OCH2), 4.42 (1 H, d, J ¼
3
11.3 Hz, CH), 7.35 (2 H, d, J ¼ 8.0 Hz, 2 CH), 7.43 (2 H, d,
3J ¼ 8.0 Hz, 2 CH). 13C-NMR: d ¼ 13.5 (Me), 14.2 (Me),
29.8 (Me3C), 37.7 (CH2Br), 58.0 (CAN), 62.7 (OCH2), 62.5
(OCH2), 90.2 (C), 128.3 (2 CH), 129.0 (2 CH), 134.0 (C),
139.2 (C), 140.8 (C), 143.6 (C), 148.9 (C), 158.5 (C¼¼N),
161.5 (C¼¼O), 162.5 (C¼¼O). Anal Calcd for C21H25BrClNO5:
C, 51.82; H, 5.18; N, 2.88; found: C, 51.64; H, 5.29; N, 2.58.
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-methoxy-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4i). Yellow crys-
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-(p-tolyl)-2,
5-dihydrofuran-3,4-dicarboxylate (4m). Pale yellow powder,
yield: 0.78 g (85%), m.p. 134–136ꢀC. IR (KBr) (mmax/cmꢁ1):
1
1735, 1684, 1631, 1587, 1281 cmꢁ1. H-NMR: d ¼ 1.38–1.57
(10 H, m, 5 CH2), 2.35 (3 H, s, Me), 3.71 (1 H, m, CH), 3.77
tals, yield: 0.79 g (87%), m.p. 135–137ꢀC. IR (KBr) (mmax
/
2
(3 H, s, MeO), 3.91 (3H, s, MeO), 4.09 (1 H, d, J ¼ 11.0 Hz,
cmꢁ1): 1725, 1684, 1657, 1580, 1267 cmꢁ1
.
1H-NMR: d ¼
2
3
CH), 4.52 (1 H, d, J ¼ 11.0 Hz, CH), 7.17 (2 H, d, J ¼ 7.6
Hz, 2 CH), 7.28 (2 H, d, J ¼ 7.6 Hz, 2 CH). 13C-NMR: d ¼
3
1.39 (9 H, s, Me3C), 3.75 (3 H, s, MeO), 3.80 (3 H, s, MeO),
2
3.95 (3 H, s, MeO), 4.15 (1 H, d, J ¼ 11.5 Hz, CH), 4.55 (1
20.9 (Me), 24.7 (2 CH2), 25.6 (CH2), 32.8 (2 CH2), 36.6
(CH2Br), 52.7 (MeO), 52.9 (MeO), 56.7 (CAN), 89.7 (C),
125.5 (2 CH), 129.4 (2 CH), 133.6 (C), 137.2 (C), 139.0 (C),
142.9 (C), 154.2 (C¼¼N), 160.9 (C¼¼O), 162.0 (C¼¼O). Anal
Calcd for C22H26BrNO5: C, 56.90; H, 5.64; N, 3.02; found: C,
56.65; H, 5.82; N, 3.32.
2
3
H, d, J ¼ 11.5 Hz, CH), 7.00 (2 H, d, J ¼ 8.5 Hz, 2 CH),
7.35 (2 H, d, 3J ¼ 8.5 Hz, 2 CH). 13C-NMR: d ¼ 29.7
(Me3C), 37.0 (CH2Br), 52.5 (MeO), 52.8 (MeO), 53.4 (MeO),
57.2 (CAN), 89.4 (C), 113.2 (2 CH), 128.5 (2 CH), 135.6 (C),
138.7 (C), 141.3 (C), 148.7 (C), 156.5 (C¼¼N), 161.0 (C¼¼O),
162.4 (C¼¼O). Anal Calcd for C20H24BrNO6: C, 52.88; H,
5.32; N, 3.08; found: C, 52.97; H, 5.53; N, 3.04.
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-(p-tolyl)-2,5-
dihydrofuran-3,4-dicarboxylate (4n). Pale yellow crystals,
yield: 0.91g (92%), m.p. 135–137ꢀC. IR (KBr) (mmax/cmꢁ1):
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(4-methoxy-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4j). Pale yellow
1
1754, 1689 1655, 1585, 1269 cmꢁ1. H-NMR: d ¼ 1.23 (3 H,
3
3
crystals, yield: 0.80 g (83%), m.p. 143–145ꢀC. IR (KBr) (mmax
/
t, J ¼ 7.3 Hz, Me), 1.34 (3 H, t, J ¼ 7.3 Hz, Me), 1.40–1.92
cmꢁ1): 1734, 1678, 1648, 1576, 1258 cmꢁ1
.
1H-NMR: d ¼
(10 H, m, 5 CH2), 2.34 (3 H, s, Me), 3.82 (1 H, m, CH), 4.15
1.24 (3 H, t, 3J ¼ 7.2 Hz, Me), 1.35 (3 H, t, 3J ¼ 7.3 Hz,
2
(1 H, d, J ¼ 11.0 Hz, CH), 4.24–4.36 (2 H, m, OCH2), 4.38
Me), 1.38 (9 H, s, Me3C), 4.15 (1 H, d, 2J ¼ 11.0 Hz, CH),
(2 H, q, 3J ¼ 7.3 Hz, OCH2), 4.52 (1 H, d, 2J ¼ 11.0 Hz,
3
3
3
4.25–4.32 (2 H, m, OCH2), 4.35 (2 H, q, J ¼ 7.3 Hz, OCH2),
CH), 7.65 (2 H, d, J ¼ 8.0 Hz, 2 CH), 8.27 (2 H, d, J ¼ 8.2
Hz, 2 CH). 13C-NMR: d ¼ 13.6 (Me), 13.9 (Me), 20.9 (Me),
24.6 (2 CH2), 25.6 (CH2), 32.8 (2 CH2), 36.7 (CH2Br), 56.5
(CAN), 61.8 (OCH2), 61.9 (OCH2), 89.6 (C), 125.6 (2 CH),
129.3 (2 CH), 133.8 (C), 137.2 (C), 138.9 (C), 142.7 (C),
154.3 (C¼¼N), 160.6 (C¼¼O), 161.6 (C¼¼O). Anal Calcd for
C24H30BrNO5: C, 58.54; H, 6.14; N, 2.84; found: C, 58.33; H,
5.92; N, 2.58.
2
3
4.54 (1 H, d, J ¼ 11.0 Hz, CH), 6.85 (2 H, d, J ¼ 8.4 Hz, 2
CH), 7.30 (2 H, d, J ¼ 8.5 Hz, 2 CH). 13C-NMR: d ¼ 13.2
3
(Me), 14.5 (Me), 29.9 (Me3C), 37.3 (CH2Br), 53.4 (MeO),
57.5 (CAN), 62.5 (OCH2), 62.8 (OCH2), 90.7 (C), 114.5 (2
CH), 127.4 (2 CH), 135.6 (C), 138.6 (C), 141.3 (C), 148.8 (C),
156.3 (C¼¼N), 161.9 (C¼¼O), 162.2 (C¼¼O). Anal Calcd for
C22H28BrNO6: C, 54.78; H, 5.85; N, 2.90; found: C, 54.55; H,
5.60; N, 2.73.
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-nitro-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4o). Yellow pow-
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-methox-
yphenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4k). Pale yellow
der, yield: 0.86 g (87%), m.p. 150–152ꢀC. IR (KBr) (mmax
/
crystals, yield: 0.86 g (90%), m.p. 137–139ꢀC. IR (KBr) (mmax
/
cmꢁ1): 1739, 1697, 1661, 1508, 1262 cmꢁ1
1.42–1.85 (10 H, m, 5 CH2), 3.72 (1 H, m, CH), 3.79 (3 H, s,
.
1H-NMR: d ¼
cmꢁ1): 1726, 1680, 1652, 1583, 1263 cmꢁ1
.
1H-NMR: d ¼
2
1.22–1.88 (10 H, m, 5 CH2), 2.35 (3 H, s, Me), 3.72 (1 H, m,
CH), 3.79 (3 H, s, MeO), 3.81 (3 H, s, MeO), 3.92 (3 H, s,
MeO), 4.10 (1 H, d, 2J ¼ 11.0 Hz, CH), 4.51 (1 H, d, 2J ¼
MeO), 3.91 (3 H, s, MeO), 4.11 (1 H, d, J ¼ 11.0 Hz, CH),
2
3
4.47 (1 H, d, J ¼ 11.0 Hz, CH), 7.66 (2 H, d, J ¼ 9.0 Hz, 2
CH), 8.24 (2 H, d, J ¼ 9.0 Hz, 2 CH). 13C-NMR: d ¼ 24.6
3
3
11.0 Hz, CH), 6.90 (2 H, d, J ¼ 8.7 Hz, 2 CH), 7.34 (2 H, d,
(2 CH2), 25.2 (CH2), 32.8 (2 CH2), 35.8 (CH2Br), 52.7 (MeO),
53.2 (MeO), 57.0 (CAN), 89.2 (C), 123.9 (2 CH), 127.1 (2
CH), 138.2 (C), 141.7 (C), 143.5 (C), 148.1 (C), 153.3
(C¼¼N), 160.7 (C¼¼O), 161.6 (C¼¼O). MS: m/z (%) ¼ 497 (Mþ
3J ¼ 8.7 Hz, 2 CH). 13C-NMR: d ¼ 24.8 (2 CH2), 25.6 (CH2),
32.8 (2 CH2), 36.7 (CH2Br), 52.7 (MeO), 52.9 (MeO), 53.1
(MeO), 56.8 (CAN), 86.5 (C), 114.2 (2 CH), 127.0 (2 CH),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

630
Z. Hossaini, H. Hamadi, F. R. Charati, M. Khoobi, and A. Shafiee
Vol 48
þ 2, 35), 495 (Mþ, 35), 415 (78), 383 (46), 318 (100), 123
(38). Anal Calcd for C21H23BrN2O7: C, 50.92; H, 4.68; N,
5.66; found: C, 50.74; H, 4.83; N, 5.85.
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-nitrophenyl)-
2,5-dihydrofuran-3,4-dicarboxylate (4p). Yellow crystals, yield:
0.94 g (90%), m.p. 168–170ꢀC. IR (KBr) (mmax/cmꢁ1): 1735,
53.1 (MeO), 56.9 (CAN), 89.5 (C), 127.3 (2 CH), 129.0 (2
CH), 135.3 (C), 137.6 (C), 142.5 (C), 148.4 (C), 153.9
(C¼¼N), 160.9 (C¼¼O), 161.9 (C¼¼O). Anal Calcd for
C21H23BrClNO5: C, 52.03; H, 4.78; N, 2.89; found: C, 52.25;
H, 4.60; N, 2.62.
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-chlo-
rophenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4t). Yellow
1
3
1675, 1655, 1582, 1260 cmꢁ1. H-NMR: d ¼ 1.27 (3 H, t, J
3
powder, yield: 0.87 g (85%), m.p. 147–149ꢀC. IR (KBr) (mmax
/
¼ 7.2 Hz, Me), 1.37 (3 H, t, J ¼ 7.2 Hz, Me), 1.46–1.91 (10
cmꢁ1): 1732, 1672, 1654, 1578, 1275 cmꢁ1
.
1H-NMR: d ¼
2
H, m, 5 CH2), 3.78 (1 H, m, CH), 4.17 (1 H, d, J ¼ 11.0 Hz,
1.27 (3 H, t, 3J ¼ 7.5 Hz, Me), 1.35 (3 H, t, 3J ¼ 7.5 Hz,
CH), 4.21–4.30 (2 H, m, OCH2), 4.39 (2 H, q, 3J ¼ 7.3 Hz,
2
3
Me), 1.45–1.87 (10 H, m, 5 CH2), 3.74 (1 H, m, CH), 4.10 (1
OCH2), 4.57 (1 H, d, J ¼ 11.0 Hz, CH), 7.53 (2 H, d, J ¼
2
8.5 Hz, 2 CH), 7.63 (2 H, d, J ¼ 8.5 Hz, 2 CH). 13C-NMR: d
3
H, d, J ¼ 11.3 Hz, CH), 4.09–4.29 (2 H, m, OCH2), 4.40 (2
3
2
H, q, J ¼ 7.5 Hz, OCH2), 4.46 (1 H, d, J ¼ 11.3 Hz, CH),
¼ 13.7 (Me), 14.0 (Me), 24.7 (2 CH2), 25.7 (CH2), 32.9 (2
CH2), 36.7 (CH2Br), 56.7 (CAN), 62.3 (OCH2), 62.4 (OCH2),
89.7 (C), 127.0 (2 CH), 128.9 (2 CH), 137.5 (C), 140.0 (C),
141.8 (C), 142.5 (C), 154.2 (C¼¼N), 160.7 (C¼¼O), 161.6
(C¼¼O). Anal Calcd for C23H27BrN2O7: C, 52.78; H, 5.20; N,
5.35; found: C, 52.57; H, 5.02; N, 5.13.
3
3
7.33 (2 H, d, J ¼ 8.0 Hz, 2 CH), 7.40 (2 H, d, J ¼ 8.0 Hz,
2 CH). 13C-NMR: d ¼ 13.7 (Me), 14.0 (Me), 24.5 (2 CH2),
25.7 (CH2), 32.8 (2 CH2), 36.3 (CH2Br), 56.8 (CAN), 62.3
(OCH2), 62.4(OCH2), 89.8 (C), 127.3 (2 CH), 128.5 (2 CH),
134.2 (C), 138.8 (C), 140 (C), 143.4 (C), 148.5 (C), 158.2
(C¼¼N), 160.5 (C¼¼O), 161.4 (C¼¼O). Anal Calcd for
C23H27BrClNO5: C, 53.87; H, 5.31; N, 2.73; found: C, 54.05;
H, 5.53; N, 2.94.
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-biphenyl-
2,5-dihydrofuran-3,4-dicarboxylate (4q). Pale yellow powder,
yield: 0.72 g (85%), m.p. 141–143ꢀC. IR (KBr) (mmax/cmꢁ1):
1
1725, 1679, 1645, 1585, 1274 cmꢁ1. H-NMR: d ¼ 1.26–1.89
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-(2-naph-
thyl)-2,5-dihydrofuran-3,4-dicarboxylate (9u). Yellow pow-
(10 H, m, 5 CH2), 3.72 (1 H, m, CH), 3.80 (3 H, s, MeO),
2
der, yield: 0.85 g (85%), m.p. 129–131ꢀC. IR (KBr) (mmax
/
3.92 (3H, s, MeO), 4.14 (1 H, d, J ¼ 11.0 Hz, CH), 4.57 (1
H, d, J ¼ 11.0 Hz, CH), 7.37 (1 H, t, J ¼ 7.6 Hz, CH), 7.45
cmꢁ1): 1742, 1694, 1658, 1595, 1276 cmꢁ1
.
1.36–1.90 (10 H, m, 5 CH2), 3.72 (1 H, m, CH), 3.76 (3 H, s,
1H-NMR: d ¼
2
3
(2 H, t, 3J ¼ 7.5 Hz, 2 CH), 7.50 (2 H, d, 3J ¼ 7.6 Hz, 2
3
3
2
CH), 7.57 (2 H, d, J ¼ 8.3 Hz, 2 CH), 7.61 (2 H, d, J ¼ 8.2
Hz, 2 CH). 13C-NMR: d ¼ 24.8 (2 CH2), 25.3 (CH2), 32.9 (2
CH2), 36.7 (CH2Br), 52.9 (MeO), 53.1 (MeO), 56.9 (CAN),
89.5 (C), 126.2 (2 CH), 127.1 (2 CH), 127.5 (2 CH), 127.8
(CH), 128.9 (2 CH), 135.6 (C), 137.5 (C), 140.0 (C), 142.0
(C), 142.9 (C), 158.7 (C¼¼N), 161.1 (C¼¼O), 162.1 (C¼¼O).
Anal Calcd for C27H28BrNO5: C, 61.60; H, 5.36; N, 2.66;
found: C, 61.45; H, 5.18; N, 2.47.
MeO), 3.92 (3 H, s, MeO), 4.24 (1 H, d, J ¼ 11.0 Hz, CH),
2
4.67 (1 H, d, J ¼ 11.0 Hz, CH), 7.49–7.91 (7 H, m, 7 CH).
13C-NMR: d ¼ 24.8 (2 CH2), 25.7 (CH2), 32.9 (2 CH2), 36.6
(CH2Br), 52.9 (MeO), 53.1 (MeO), 56.9 (CAN), 90.7 (C),
123.0 (CH), 125.5 (CH), 126.7 (CH), 127.1 (CH), 127.6 (CH),
128.5 (CH), 128.8 (CH), 132.9 (C), 133.2 (C), 133.9 (C),
146.7 (C), 148.5 (C), 156.4 (C¼¼N), 161.0 (C¼¼O), 162.1
(C¼¼O). MS: m/z (%) ¼ 501 (Mþ þ 2, 25), 499 (Mþ, 25), 420
(100), 388 (48), 323 (70), 127 (58). Anal Calcd for
C25H26BrNO5: C, 60.01; H, 5.24; N, 2.80; found: C, 60.22; H,
5.50; N, 2.97.
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-biphenyl-2,5-
dihydrofuran-3,4-dicarboxylate (4r). Orange powder, yield:
0.95 g (86%), m.p. 168–170ꢀC. IR (KBr) (mmax/cmꢁ1): 1735,
1
3
1675, 1667, 1582, 1279 cmꢁ1. H-NMR: d ¼ 1.28 (3 H, t, J
Diethyl 2-bromomethyl-5-(cyclohexylimino)-2-(2-naphthyl)-
2,5-dihydrofuran-3,4-dicarboxylate (9v). Yellow powder,
yield: 0.92 g (87%), m.p. 150–152ꢀC. IR (KBr) (mmax/cmꢁ1):
3
¼ 7.3 Hz, Me), 1.35 (3 H, t, J ¼ 7.4 Hz, Me), 1.27–1.86 (10
2
H, m, 5 CH2), 3.75 (1 H, m, CH), 4.23 (1 H, d, J ¼ 11.0 Hz,
CH), 4.25–4.32 (2 H, m, OCH2), 4.38 (2 H, q, 3J ¼ 7.4 Hz,
1
1754, 1684, 1625, 1580, 1280 cmꢁ1. H-NMR: d ¼ 1.23 (3 H,
OCH2), 4.56 (1 H, d, 2J ¼ 11.2 Hz, CH), 7.35 (1 H, t, 3J ¼
3
3
t, J ¼ 7.4 Hz, Me), 1.36 (3 H, t, J ¼ 7.5 Hz, Me), 1.43–1.90
3
7.5 Hz, CH), 7.42 (2 H, t, J ¼ 7.6 Hz, 2 CH), 7.53 (2 H, d,
(10 H, m, 5 CH2), 3.79 (1 H, m, CH), 4.17–4.23 (2 H, m,
3J ¼ 7.6 Hz, 2 CH), 7.58 (2 H, d, J ¼ 8.4 Hz, 2 CH), 7.65 (2
3
2
3
OCH2), 4.25 (1 H, d, J ¼ 11.0 Hz, CH), 4.38 (2 H, q, J ¼
H, d, 3J ¼ 8.4 Hz, 2 CH). 13C-NMR: d ¼ 13.5 (Me), 13.8
(Me), 24.7 (2 CH2), 25.2 (CH2), 33.0 (2 CH2), 37.5 (CH2Br),
57.6 (CAN), 62.0 (OCH2), 62.8 (OCH2), 89.3 (C), 127.2 (2
CH), 127.8 (2 CH), 128.2 (2 CH), 128.7 (CH), 129.2 (2 CH),
136.3 (C), 137.7 (C), 141.3 (C), 142.5 (C), 142.9 (C), 158.4
(C¼¼N), 161.51 (C¼¼O), 162.9 (C¼¼O). Anal Calcd for
C29H32BrNO5: C, 62.82; H, 5.82; N, 2.53; found: C, 62.64; H,
5.68; N, 2.36.
2
7.5 Hz, OCH2), 4.64 (1 H, d, J ¼ 11.0 Hz, CH), 7.50–7.92 (7
H, m, 7 CH). 13C-NMR: d ¼ 13.8 (Me), 14.1 (Me), 24.7 (2
CH2), 25.8 (CH2), 32.9 (2 CH2), 36.8 (CH2Br), 56.8 (CAN),
62.1 (OCH2), 62.2 (OCH2), 90.2 (C), 123.1 (CH), 125.5 (CH),
126.7 (CH), 127.0 (CH), 127.6 (CH), 128.5 (CH), 128.7 (CH),
132.9 (C), 133.2 (C), 134.2 (C), 145.7 (C), 148.5 (C), 156.6
(C¼¼N), 161.3 (C¼¼O), 162.0 (C¼¼O). Anal Calcd for
C27H30BrNO5: C, 61.37; H, 5.72; N, 2.65; found: C, 61.13; H,
5.60; N, 2.41.
Dimethyl 2-bromomethyl-5-(cyclohexylimino)-2-(4-chloro-
phenyl)-2,5-dihydrofuran-3,4-dicarboxylate (4s). Yellow pow-
Dimethyl 2-bromomethyl-5-(tert-butylimino)-2-(2-naph-
thyl)-2,5-dihydrofuran-3,4-dicarboxylate (9w). Yellow pow-
der, yield: 0.84g (87%), m.p. 158–160ꢀC. IR (KBr) (mmax
/
cmꢁ1): 1735, 1684, 1631, 1587, 1281 cmꢁ1
1.22–1.89 (10 H, m, 5 CH2), 3.71 (1 H, m, CH), 3.79 (3 H, s,
.
1H-NMR: d ¼
der, yield: 0.79 g (84%), m.p. 145–147ꢀC. IR (KBr) (mmax
/
cmꢁ1): 1745, 1697, 1668, 1590, 1278 cmꢁ1
.
1H-NMR: d ¼
2
MeO), 3.93 (3 H, s, MeO), 4.08 (1 H, d, J ¼ 11.1 Hz, CH),
1.37 (9 H, s, Me3C), 3.75 (3 H, s, MeO), 3.89 (3 H, s, MeO),
2
3
2
2
4.48 (1 H, d, J ¼ 11.1 Hz, CH), 7.37 (2 H, d, J ¼ 8.2 Hz, 2
4.27 (1 H, d, J ¼ 11.3 Hz, CH), 4.65 (1 H, d, J ¼ 11.3 Hz,
CH), 7.45–7.92 (7 H, m, 7 CH). 13C-NMR: d ¼ 29.8 (Me3C),
37.8 (CH2Br), 52.5 (MeO), 52.9 (MeO), 57.8 (CAN), 90.5
CH), 7.39 (2 H, d, J ¼ 8.2 Hz, 2 CH). 13C-NMR: d ¼ 24.8
3
(2 CH2), 25.7 (CH2), 32.9 (2 CH2), 36.4 (CH2Br), 52.9 (MeO),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2011
Isocyanide-Based Three-Component Synthesis of Functionalized 5-Alkylimino-
2,5-dihydrofuran-3,4-dicarboxylate and Their Conversion to Substituted Furanones
631
2
3
(C), 123.2 (CH), 125.6 (CH), 126.8 (CH), 127.5 (CH), 127.8
(CH), 128.4 (CH), 128.9 (CH), 132.8 (C), 133.5 (C), 134.0
(C), 146.5 (C), 148.8 (C), 156.6 (C¼¼N), 161.7 (C¼¼O), 162.8
(C¼¼O). Anal Calcd for C23H24BrNO5: C, 58.24; H, 5.10; N,
2.95; found: C, 58.42; H, 5.28; N, 3.16.
4.45 (1 H, d, J ¼ 11.5 Hz, CH), 7.55 (2 H, d, J ¼ 8.4 Hz, 2
CH), 8.27 (2 H, d, J ¼ 8.4 Hz, 2 CH). 13C-NMR: d ¼ 34.5
3
(CH2Br), 52.6 (MeO), 53.2 (MeO), 90.2 (C), 122.7 (2 CH),
128.4 (2 CH), 138.7 (C), 141.0 (C), 142.7 (C), 147.8 (C),
158.4 (C¼¼O), 161.2 (C¼¼O), 162.0 (C¼¼O). Anal Calcd for
C15H12BrNO8: C, 43.50; H, 2.92; N, 3.38; found: C, 43.38; H,
2.84; N, 3.25.
Diethyl 2-bromomethyl-5-(tert-butylimino)-2-(2-naphthyl)-
2,5-dihydrofuran-3,4-dicarboxylate (9x). Yellow powder,
yield: 0.85 g (85%), m.p. 153–155ꢀC. IR (KBr) (mmax/cmꢁ1):
Diethyl 2-bromomethyl-5-oxo-2-(4-nitrophenyl)-2,5-dihy-
drofuran-3,4-dicarboxylate (5d). Pale yellow powder, yield:
0.75 g (85%), m.p. 162–164ꢀC. IR (KBr) (mmax/cmꢁ1): 1757,
1
1752, 1687, 1637, 1595, 1278 cmꢁ1. H-NMR: d ¼ 1.27 (3 H,
3
3
t, J ¼ 7.2 Hz, Me), 1.32 (3 H, t, J ¼ 7.3 Hz, Me), 1.38 (9
1687, 1667, 1592, 1248, 1147 cmꢁ1. H-NMR: d ¼ 1.25 (3 H,
1
H, s, Me3C), 4.17–4.23 (2 H, m, OCH2), 4.25 (1 H, d, 2J ¼
3
3
3
t, J ¼ 7.3 Hz, Me), 1.35 (3 H, t, J ¼ 7.3 Hz, Me), 4.12 (1
11.2 Hz, CH), 4.38 (2 H, q, J ¼ 7.5 Hz, OCH2), 4.64 (1 H, d,
2
2J ¼ 11.2 Hz, CH), 7.50–7.92 (7 H, m, 7 CH). 13C-NMR: d ¼
13.8 (Me), 14.1 (Me), 1.38 (9 H, s, Me3C), 37.8 (CH2Br), 57.4
(CAN), 62.4 (OCH2), 62.8 (OCH2), 89.6 (C), 123.5 (CH),
125.8 (CH), 127.0 (CH), 127.5 (CH), 127.8 (CH), 128.7 (CH),
129.1 (CH), 133.2 (C), 133.8 (C), 134.6 (C), 146.2 (C), 148.2
(C), 157.6 (C¼¼N), 162.3 (C¼¼O), 162.8 (C¼¼O). Anal Calcd
for C25H28BrNO5: C, 59.77; H, 5.62; N, 2.79; found: C, 59.58;
H, 5.83; N, 2.55.
H, d, J ¼ 10.8 Hz, CH), 4.25–4.31 (2 H, m, OCH2), 4.37 (1
2
3
H, d, J ¼ 10.8 Hz, CH), 4.42 (2 H, q, J ¼ 7.3 Hz, OCH2),
3
3
7.65 (2 H, d, J ¼ 8.2 Hz, 2 CH), 8.25 (2 H, d, J ¼ 8.2 Hz,
2 CH). 13C-NMR: d ¼ 13.8 (Me), 14.0 (Me), 37.2 (CH2Br),
61.8 (OCH2), 62.4 (OCH2), 91.4 (C), 123.7 (2 CH), 128.7 (2
CH), 141.3 (C), 141.7 (C), 142.8 (C), 147.6 (C), 159.4
(C¼¼O), 161.0 (C¼¼O), 162.3 (C¼¼O). Anal Calcd for
C17H16BrNO8: C, 46.17; H, 3.65; N, 3.17; found: C, 46.22; H,
3.41; N, 3.05.
General procedure for the preparation of compounds
5a–5j and 5u–5v. To a stirred solution of 5-alkylimino-2,5-
dihydrofuran-3,4-dicarboxylate 4 (2 mmol) in 5 mL of CH2Cl2
was added aqueous HCl (5%, 5 mL) slowly at room tempera-
ture. After stirring the reaction mixture for 5 h, it was diluted
by adding CH2Cl2 (2 mL) and H2O (3 mL). The mixture was
stirred for additional 30 min and two layers were separated.
The aqueous layer was extracted with CH2Cl2 (3 mL ꢂ 3).
The combined organic layers were dried over Na2SO4, filtered,
and concentrated in vacuo. The residue was purified by col-
umn chromatography (SiO2; n-hexanes/EtOAc 8:1) to afford
pure desired products.
Dimethyl 2-bromomethyl-5-oxo-2-(p-biphenyl)-2,5-dihydro-
furan-3,4-dicarboxylate (5e). Pale yellow powder, yield: 0.71
g (80%), m.p. 145–147ꢀC. IR (KBr) (mmax/cmꢁ1): 1735, 1668,
1654, 1572, 1275, 1124 cmꢁ1
.
1H-NMR: d ¼ 3.80 (3 H, s,
MeO), 3.87 (3H, s, MeO), 4.18 (1 H, d, 2J ¼ 11.0 Hz, CH),
4.38 (1 H, d, 2J ¼ 11.0 Hz, CH), 7.35 (1 H, t, 3J ¼ 7.5 Hz,
3
3
CH), 7.38 (2 H, t, J ¼ 7.4 Hz, 2 CH), 7.52 (2 H, d, J ¼ 7.5
3
3
Hz, 2 CH), 7.58 (2 H, d, J ¼ 8.0 Hz, 2 CH), 7.67 (2 H, d, J
¼ 8.2 Hz, 2 CH). 13C-NMR: d ¼ 38.4 (CH2Br), 51.7 (MeO),
52.6 (MeO), 90.8 (C), 127.5 (2 CH), 128.2 (2 CH), 128.6 (2
CH), 129.2 (CH), 129.8 (2 CH), 135.8 (C), 138.4 (C), 141.5
(C), 142.4 (C), 143.7 (C), 159.4 (C¼¼O), 162.3 (C¼¼O), 162.7
(C¼¼O). Anal Calcd for C21H17BrO6: C, 56.65; H, 3.85; found:
C, 56.88; H, 3.69.
Dimethyl 2-bromomethyl-5-oxo-2-(p-tolyl)-2,5-dihydrofuran-
3,4-dicarboxylate (5a). White crystals yield: 0.63 g (82%), m.p.
125–127ꢀC. IR (KBr) (mmax/cmꢁ1): 1720, 1675, 1648, 1582,
1265 cmꢁ1
.
1H-NMR: d ¼ 2.29 (3 H, s, Me), 3.75 (3 H, s,
Diethyl 2-bromomethyl-5-oxo-2-(p-biphenyl)-2,5-dihydro-
furan-3,4-dicarboxylate (5f). White powder, yield: 0.72 g
(76%), m.p. 158–160ꢀC. IR (KBr) (mmax/cmꢁ1): 1728, 1664,
2
MeO), 3.82 (3 H, s, MeO), 4.15 (1 H, d, J ¼ 11.2 Hz, CH),
2
3
4.50 (1 H, d, J ¼ 11.2 Hz, CH), 7.12 (2 H, d, J ¼ 7.5 Hz, 2
1648, 1594, 1268, 1157 cmꢁ1. H-NMR: d ¼ 1.24 (3 H, t, J
1
3
CH), 7.28 (2 H, d, J ¼ 7.5 Hz, 2 CH). 13C-NMR: d ¼ 21.4
3
3
¼ 7.3 Hz, Me), 1.32 (3 H, t, J ¼ 7.4 Hz, Me), 4.16 (1 H, d,
(Me), 36.5 (CH2Br), 51.8 (MeO), 52.3 (MeO), 92.4 (C), 125.2
(2 CH), 129.0 (2 CH), 133.6 (C), 138.4 (C), 139.0 (C), 141.7
(C), 158.7 (C¼¼O), 161.7 (C¼¼O), 162.4 (C¼¼O). Anal Calcd
for C16H15BrNO6: C, 50.15; H, 3.95; found: C, 49.95; H, 3.87.
Diethyl 2-bromomethyl-5-oxo-2-(p-tolyl)-2,5-dihydrofuran-
3,4-dicarboxylate (5b). White powder, yield: 0.66 g (80%),
m.p. 116–118ꢀC. IR (KBr) (mmax/cmꢁ1): 1725, 1715, 1700,
2J ¼ 11.5 Hz, CH), 4.25–4.32 (2 H, m, OCH2), 4.38 (2 H, q,
3J ¼ 7.3 Hz, OCH2), 4.47 (1 H, d, J ¼ 11.5 Hz, CH), 7.27 (1
2
3
3
H, t, J ¼ 7.4 Hz, CH), 7.36 (1 H, t, J ¼ 7.5 Hz, CH), 7.42
(2 H, d, 3J ¼ 7.5 Hz, 2 CH), 7.52 (2 H, d, 3J ¼ 8.2 Hz, 2
CH), 7.58 (2 H, d, J ¼ 8.2 Hz, 2 CH). 13C-NMR: d ¼ 13.9
3
(Me), 14.0 (Me), 37.2 (CH2Br), 61.4 (OCH2), 62.4 (OCH2),
91.4 (C), 127.6 (2 CH), 127.8 (2 CH), 128.3 (2 CH), 128.7
(CH), 129.2 (2 CH), 137.4 (C), 138.0 (C), 141.3 (C), 142.7
(C), 143.5 (C), 159.3 (C¼¼O), 161.8 (C¼¼O), 163.2 (C¼¼O).
MS: m/z (%) ¼ 474 (Mþ þ 2, 10), 472 (Mþ, 10), 428 (58),
321 (78), 154 (100), 152 (48), 45 (68). Anal Calcd for
C23H21BrO6: C, 58.36; H, 4.47; found: C, 58.50; H, 4.25.
Dimethyl 2-bromomethyl-5-oxo-2-(4-chlorophenyl)-2,5-
dihydrofuran-3,4-dicarboxylate (5g). Pale yellow powder,
yield: 0.66 g (82%), m.p. 135–137ꢀC. IR (KBr) (mmax/cmꢁ1):
1210 cmꢁ1
.
1H-NMR: d ¼ 1.26 (3 H, t, 3J ¼ 7.2 Hz, Me),
3
1.35 (3 H, t, J ¼ 7.2 Hz, Me), 2.35 (3 H, s, Me), 4.09 (1 H,
d, 2J ¼ 11.1 Hz, CH), 4.26–4.32 (2 H, m, OCH2), 4.33–4.39
2
(2 H, q, OCH2), 4.45 (1 H, d, J ¼ 11.1 Hz, CH), 7.18 (2 H,
3
3
d, J ¼ 7.6 Hz, 2 CH), 7.29 (2 H, d, J ¼ 7.5 Hz, 2 CH). 13C-
NMR: d ¼ 13.6 (Me), 14.0 (Me), 21.0 (Me), 35.4 (CH2Br),
62.5 (OCH2), 62.8 (OCH2), 87.4 (C), 125.5 (2 CH), 129.5 (C),
129.6 (2 CH), 130.9 (C), 139.9 (C), 155.1 (C), 159.9 (C¼¼O),
160.2 (C¼¼O), 165.4 (C¼¼O). Anal Calcd for C18H19BrO6: C,
52.57; H, 4.66; found: C, 52.40; H, 4.38.
1736, 1678, 1643, 1567, 1248, 1157 cmꢁ1. H-NMR: d ¼ 3.78
1
(3 H, s, MeO), 3.86 (3 H, s, MeO), 4.15 (1 H, d, 2J ¼ 10.5
Dimethyl 2-bromomethyl-5-oxo-2-(4-nitrophenyl)-2,5-dihy-
drofuran-3,4-dicarboxylate (5c). Yellow powder, yield: 0.68 g
(82%), m.p. 148–150ꢀC. IR (KBr) (mmax/cmꢁ1): 1737, 1683,
2
3
Hz, CH), 4.45 (1 H, d, J ¼ 10.5 Hz, CH), 7.32 (2 H, d, J ¼
8.2 Hz, 2 CH), 7.38 (2 H, d, J ¼ 8.2 Hz, 2 CH). 13C-NMR: d
3
1652, 1574, 1225, 1154 cmꢁ1
MeO), 3.87 (3 H, s, MeO), 4.20 (1 H, d, J ¼ 11.5 Hz, CH),
.
1H-NMR: d ¼ 3.82 (3 H, s,
¼ 38.6 (CH2Br), 51.7 (MeO), 52.6 (MeO), 90.8 (C), 128.4 (2
2
CH), 128.8 (2 CH), 136.4 (C), 138.2 (C), 143.3 (C), 148.6 (C),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

632
Z. Hossaini, H. Hamadi, F. R. Charati, M. Khoobi, and A. Shafiee
Vol 48
158.9 (C¼¼O), 162.3 (C¼¼O), 163.4 (C¼¼O). Anal Calcd for
C15H12BrClO6: C, 44.64; H, 3.00; found: C, 44.49; H, 3.23.
Diethyl 2-bromomethyl-5-oxo-2-(4-chlorophenyl)-2,5-dihy-
drofuran-3,4-dicarboxylate (5h). White powder, yield: 0.69 g
(80%), m.p. 147–149ꢀC. IR (KBr) (mmax/cmꢁ1): 1725, 1675,
(CH), 125.4 (CH), 126.9 (CH), 127.3 (CH), 127.5 (CH),
128.3 (CH), 129.1 (CH), 129.5 (C), 130.9 (C), 132.8 (C),
133.3 (C), 155.1 (C), 159.7 (C¼¼O), 160.2 (C¼¼O), 165.4
(C¼¼O). Anal Calcd for C21H19BrO6: C, 56.39; H, 4.28;
found: C, 56.62; H, 4.09.
1
3
1660, 1574, 1265, 1148 cmꢁ1. H-NMR: d ¼ 1.23 (3 H, t, J
3
¼ 7.3 Hz, Me), 1.30 (3 H, t, J ¼ 7.3 Hz, Me), 4.25 (1 H, d,
Acknowledgment. The authors gratefully acknowledge finan-
cial and spiritual support from the National Endowment for the
Elite.
2J ¼ 11.0 Hz, CH), 4.25–4.30 (2 H, m, OCH2), 4.36 (2 H, q,
2
3J ¼ 7.4 Hz, OCH2), 4.43 (1 H, d, J ¼ 11.0 Hz, CH), 7.28 (2
3
3
H, d, J ¼ 7.8 Hz, 2 CH), 7.37 (2 H, d, J ¼ 7.8 Hz, 2 CH).
13C-NMR: d ¼ 13.8 (Me), 14.0 (Me), 37.5 (CH2Br), 61.6
(OCH2), 62.3 (OCH2), 91.5 (C), 127.8 (2 CH), 128.7 (2 CH),
133.8 (C), 139.3 (C), 141.4 (C), 143.5 (C), 148.7 (C), 159.4
(C¼¼O), 161.9 (C¼¼O), 162.7 (C¼¼O). Anal Calcd for
C17H16BrClO6: C, 47.30; H, 3.75; found: C, 47.57; H, 3.99.
Dimethyl 2-bromomethyl-5-oxo-2-(4-methoxyphenyl)-2,5-
dihydrofuran-3,4-dicarboxylate (5i). Yellow powder, yield:
0.68 g (85%), m.p. 142–144ꢀC. IR (KBr) (mmax/cmꢁ1): 1738,
REFERENCES AND NOTES
[1] Dean, F. M. In Advanced Heterocyclic Chemistry; Katritzky,
A. R., Eds.; Academic Press: New York, 1982; Vol. 30, p 167.
[2] Dunlop, A. P.; Peters, F. N. The Furans; Reinhold: New
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[3] Corey, E. J.; Cheng, X. M. The Logic of Chemical Synthe-
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1
1680, 1648, 1567, 1257, 1124 cmꢁ1. H-NMR: d ¼ 3.78 (3 H,
[4] Benassi, R. In Comprehensive Heterocyclic Chemistry II;
Katritzky, A. R., Rees, C. W., Scriven, E. F. V., Eds.; Pergamon:
Oxford, 1996; Vol. 2, p 259.
s, MeO), 3.82 (3 H, s, MeO), 3.94 (3 H, s, MeO), 4.12 (1 H,
2
2
d, J ¼ 11.3 Hz, CH), 4.38 (1 H, d, J ¼ 11.3 Hz, CH), 7.14
(2 H, d, 3J ¼ 8.2 Hz, 2 CH), 7.38 (2 H, d, 3J ¼ 8.2 Hz, 2
CH). 13C-NMR: d ¼ 37.6 (CH2Br), 51.3 (MeO), 52.2 (MeO),
53.6 (MeO), 92.0 (C), 114.0 (2 CH), 128.7 (2 CH), 136.2 (C),
138.5 (C), 142.3 (C), 147.8 (C), 158.9 (C¼¼O), 161.4 (C¼¼O),
162.5 (C¼¼O). Anal Calcd for C16H15BrO7: C, 48.14; H, 3.79;
found: C, 48.37; H, 3.92.
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Diethyl 2-bromomethyl-5-oxo-2-(4-methoxyphenyl)-2,5-
dihydrofuran-3,4-dicarboxylate (5j). Yellow crystals, yield:
0.67 g (78%), m.p. 146–148ꢀC. IR (KBr) (mmax/cmꢁ1): 1745,
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1700, 1684, 1625, 1485, 1378 cmꢁ1. H-NMR: d ¼ 1.25 (3 H,
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3
3
t, J ¼ 7.2 Hz, Me), 1.32 (3 H, t, J ¼ 7.3 Hz, Me), 4.08 (1
2
H, d, J ¼ 11.2 Hz, CH), 4.20–4.26 (2 H, m, OCH2), 4.34 (2
3
2
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H, q, J ¼ 7.3 Hz, OCH2), 4.38 (1 H, d, J ¼ 11.2 Hz, CH),
3
3
6.74 (2 H, d, J ¼ 8.4 Hz, 2 CH), 7.36 (2 H, d, J ¼ 8.4 Hz,
2 CH). 13C-NMR: d ¼ 13.6 (Me), 14.2 (Me), 38.2 (CH2Br),
52.8 (MeO), 61.8 (OCH2), 62.3 (OCH2), 91.3 (C), 113.8 (2
CH), 127.8 (2 CH), 136.3 (C), 138.5 (C), 142.4 (C), 148.5 (C),
158.8 (C¼¼O), 162.4 (C¼¼O), 163.2 (C¼¼O). Anal Calcd for
C18H19BrO7: C, 50.60; H, 4.48; found: C, 50.37; H, 4.71.
Dimethyl 2-bromomethyl-5-oxo-(2-naphthyl)-2,5-dihydro-
furan-3,4-dicarboxylate (5u). Yellow powder, yield: 0.70 g
(83%), m.p. 134–136ꢀC. IR (KBr) (mmax/cmꢁ1): 1745, 1715,
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1682, 1597, 1452, 1354, 1245 cmꢁ1. H-NMR: d ¼ 3.75 (3 H,
1
s, MeO), 3.87 (3 H, s, MeO), 4.18 (1 H, d, 2J ¼ 10.8 Hz,
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2
CH), 4.47 (1 H, d, J ¼ 10.8 Hz, CH), 7.35–7.42 (7 H, m, 7
CH). 13C-NMR: d ¼ 37.4 (CH2Br), 51.7 (MeO), 52.8 (MeO),
92.2 (C), 122.8 (CH), 124.5 (CH), 125.7 (CH), 127.8 (CH),
128.2 (CH), 128.6 (CH), 129.3 (CH), 133.4 (C), 133.8 (C),
134.5 (C), 145.8 (C), 147.6 (C), 159.7 (C¼¼O), 161.8 (C¼¼O),
162.5 (C¼¼O). Anal Calcd for C19H15BrO6: C, 54.43; H, 3.61;
found: C, 54.64; H, 3.37.
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Diethyl 2-bromomethyl-5-oxo-2-(2-naphthyl)-2,5-dihydro-
furan-3,4-dicarboxylate (5v). Yellow powder, yield: 0.76 g
(85%), m.p. 125–127ꢀC. IR (KBr) (mmax/cmꢁ1): 1752, 1735,
1725, 1234 cmꢁ1
.
1H-NMR: d ¼ 1.26 (3 H, t, 3J ¼ 7.2 Hz,
Me), 1.36 (3 H, t, 3J ¼ 7.4 Hz, Me), 4.22 (1 H, d, 2J ¼
11.1 Hz, CH), 4.27–4.31 (2 H, m, OCH2), 4.34 (2 H, q, 3J
¼ 7.4 Hz, OCH2), 4.60 (1 H, d, 2J ¼ 11.1 Hz, CH), 7.45–
7.94 (7 H, m, 7 CH). 13C-NMR: d ¼ 13.6 (Me), 13.9 (Me),
35.3 (CH2Br), 62.6 (OCH2), 62.9 (OCH2), 87.4 (C), 122.1
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2011
Isocyanide-Based Three-Component Synthesis of Functionalized 5-Alkylimino-
2,5-dihydrofuran-3,4-dicarboxylate and Their Conversion to Substituted Furanones
633
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet