A facile synthesis of N,N′-oligomethylenebis(4,5-dihydrofuran-3- carboxamide)s using manganese(III)-based radical cyclization of N,N′-oligomethylenebis(3-oxobutanamide)s with 1,1-diarylethenes

Article abstract of DOI:10.1002/jhet.5570420713

The reaction of N,N′-oligomethylenebis(3-oxobutanamide)s with 1,1-diarylethenes in the presence of manganese(III) acetate in acetic acid at 100° produced N,N′-oligomethylenebis(2-methyl-5,5-diaryl-4,5- dihydrofuran-3-carboxamide)s. Similarly, the reaction of 3-oxobutanamidoethyl 3-oxobutanoate or N,N′-(3,6-dioxaoctamethylene)bis(3-oxobutanamide) with 1,1-diphenylethene gave (2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-amido)ethyl 2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxylate or N,N′-(3,6-dioxa- octamethylene)bis(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxamide) in moderate yields.

Full text of DOI:10.1002/jhet.5570420713

Nov-Dec 2005
A Facile Synthesis of N,N'-Oligomethylenebis(4,5-dihydrofuran-3-
carboxamide)s Using Manganese(III)-Based Radical Cyclization of
N,N'-Oligomethylenebis(3-oxobutanamide)s with 1,1-Diarylethenes
1337
Firoz Alam Chowdhury
Department of Environmental Science, Graduate School of Science and Technology, Kumamoto University,
Kurokami 2-39-1, Kumamoto 860-8555, Japan
Hiroshi Nishino*
Department of Chemistry, Faculty of Science, Kumamoto University,
Kurokami 2-39-1, Kumamoto 860-8555, Japan
Received March 18, 2005
The reaction of N,N'-oligomethylenebis(3-oxobutanamide)s with 1,1-diarylethenes in the presence of
manganese(III) acetate in acetic acid at 100° produced N,N'-oligomethylenebis(2-methyl-5,5-diaryl-4,5-
dihydrofuran-3-carboxamide)s. Similarly, the reaction of 3-oxobutanamidoethyl 3-oxobutanoate or N,N'-
(
3,6-dioxaoctamethylene)bis(3-oxobutanamide) with 1,1-diphenylethene gave (2-methyl-5,5-diphenyl-4,5-
dihydrofuran-3-amido)ethyl 2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxylate or N,N'-(3,6-dioxa-
octamethylene)bis(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxamide) in moderate yields.
J. Heterocyclic Chem., 42, 1337 (2005).
Introduction.
During the past decades, manganese(III)-based oxida-
tive free-radical cyclizations have been developed into a
versatile protocol for the formation of highly functional-
ized products from simple precursors. Manganese(III)
acetate is well-known as a mild one-electron oxidant
which leads to formal dicarbonylmethyl radicals,
•
1
CH(COR)COR', from 1,3-dicarbonyl compounds [1-
1]. Reactions involving such species with alkenes or
alkynes have attracted considerable attention. The works
of Heiba [12,13], Fristad [14-16], Corey [17-20], Snider
[
7], and others [21-33] are noteworthy, since they pro-
vided mechanistic descriptions and synthetic applications
of this chemistry that include inter- and intra-molecular
cyclization processes. In our previous papers [34-45], we
have described that the reactions of 1,3-dicarbonyl com-
pounds with monoalkenes and terminal dienes in the
presence of tris(2,4-pentanedionato)manganese(III),
manganese(III) acetate, or tris(2,4-pentanedionato)-
cobalt(III) at elevated temperature produced dihydrofu-
rans in good yields. Heiba and Dessau reported that the
reaction of alkenes with β-diketones and β-keto esters in
the presence of manganese(III) acetate also gave the cor-
responding dihydrofurans [13]. Corey applied these
methods to enol ethers and obtained 2-alkoxy-2,3-dihy-
drofurans which were transformed into fused or spiro 2-
cyclopentenones or converted into the corresponding
furans in good yields [19,20]. The reaction of 1,3-dicar-
bonyl compounds with alkenes in the presence of thal-
lium(III) acetate [46], lead(IV) acetate [47], silver oxide,
and lead(IV) oxide [48] have also been reported to give
dihydrofurans. It was expected that N,N'-oligomethyl-
enebis(3-oxobutanamide)s would be oxidized by man-
ganese(III) acetate via a manner similar to the oxidation
of 1,3-dicarbonyl compounds to give the corresponding
formal biradicals, which would attack alkenic double
bonds to produce the corresponding bis(dihydrofuran)s.
Thus, we examined the reaction of various N,N'-
oligomethylenebis(3-oxobutanamide)s with 1,1-diaryl-

1
338
F. A. Chowdhury and H. Nishino
Vol. 42
Table 2
ethenes in the presence of manganese(III) acetate, and
found that they provided a convenient route for the syn-
thesis of bis(dihydrofuran)s. The results of the reactions
and the reaction mechanism are presented in this paper.
Reaction of N,N'-Oligomethylenebis(3-oxobutanamide)s 1n (n = 3-8)
with 1,1-Diphenylethene (2a) in the Presence of Manganese(III)
Acetate in Acetic Acid at 100° [a]
Entry Diamine Alkene 1n:2a:Mn(III) Time
Product
min
Yield/% [b]
Table 1
Reaction of N,N'-Ethylenebis(3-oxobutanamide) (1 ) with
1
2
3
4
5
6
13
14
15
16
17
18
2a
2a
2a
2a
2a
2a
0.5:1.2:4
0.5:1.2:4
0.5:1.2:4
0.5:1.2:4
0.5:1.2:4
0.5:1.2:4
20
20
14
16
20
23
33a (43)
34a (40)
35a (35)
36a (37)
37a (35)
38a (32)
2
1
,1-Diarylethenes 2a-d in the Presence of Manganese(III)
Acetate in Acetic Acid at 100° [a]
Entry Diamine Alkene 12:2:Mn(III)
Time
min
Product
Yield/% [b]
[
a] The reactions were carried out in acetic acid (30 mL) at 100° under an
1
2
3
4
5
6
7
8
9
12
12
12
12
12
12
12
12
2a
2a
2a
2a
2a
2b
2c
2d
2a
2:1:2.5
0.5:1:3
5
23
20
25
30
20
16
10
15
32a (8) 42a (31)
32a (34)
32a (38)
32a (45)
32a (30)
32b (37)
32c (52)
32d (31)
32a (63)
argon atmosphere. [b] The yields were based on the amount of 1 used
.
n
0.5:1:3.5
0.5:1.2:4
0.5:1.2:4 [c]
0.5:1.2:4
0.5:1.2:4
0.5:1.2:4
0.5:0.6:2
(4 a), together with a small amount of benzophenone
(Scheme 1). The yields also significantly varied depend-
ing on the molar ratio of 1 :2a:manganese(III) acetate
Table 1).
2
2
(
4 a
2
In the reaction of 1 with 2a at a higher molar ratio, the
2
[
a] The reactions were carried out in acetic acid (30 mL) at 100° under an
mono(dihydrofuran) 4 a was the predominant product
2
argon atmosphere. [b] The yields were based on the amount of 12 used
except for entries 1 and 9 of which the yields were based on 2a and 4 a,
respectively. [c] The reaction was conducted in air.
(
Table 1, Entry 1). The expected bis(dihydrofuran) 3 a, on
2
2
the other hand, was optimized in the reaction at a molar
ratio of 0.5:1.2:4 for 1 :2a:manganese(III) acetate up to a
2
4
5% yield (Entry 4). Similar results for the synthesis of
Results and Discussion.
the bis(dihydrofuran)s were obtained by the reaction of 12
with 1,1-diarylethenes 2b-d in the presence of man-
ganese(III) acetate, and the yields are listed in Table 1
Reaction of N,N'-Ethylenebis(3-oxobutanamide) 1 with
,1-Diarylethenes 2a-d in the Presence of Manganese(III)
Acetate at 100°.
2
1
(
Entries 6-8). The best yield of the bis(dihydrofuran) 32
was achieved for the reaction of 1c having a methyl group
on the aromatic ring with 1 (Entry 7). The presence of a
2
remaining active methylene in compound 4 a indicated the
2
possibility of forming another 4,5-dihydrofuran ring by the
reaction of the alkene in the presence of manganese(III)
acetate. The yield of 3 a was increased up to 63% when a
2
mixture of 4 a and 2a was allowed to react with man-
2
ganese(III) acetate in acetic acid at 100° (Entry 9).
Reaction of N,N'-Oligomethylenebis(3-oxobutanamide)s
1n (n = 3-8) with 1,1-Diphenyl-ethene (2a) in the Presence
of Manganese(III) Acetate in Acetic Acid at 100°.
A similar reaction with 1 (n = 3-8) was applied to 2a
n
using manganese(III) acetate (Scheme 2), and the yields
are listed in Table 2 (Entries 1-6). It was found that the
longer the methylene chain length of 1 , the lower the
n
yield of 3 a. Similar reactions of 3-oxobutanamidoethyl
n
3
-oxobutanoate 5 and N,N'-(3,6-dioxaoctamethylene)-
bis(3-oxobutanamide) 7 with 2a were carried out, and the
corresponding bis(dihydrofuran)s 6 and 8 were obtained in
61% and 33% yields, respectively (Scheme 3).
It was found that the replacement of one nitrogen atom
by oxygen in the case of 5 increased the yield of bis(dihy-
drofuran). On the other hand, the yields of bis(dihydrofu-
ran)s 3 and 8 were medium or low in both cases since the
When the reaction of 1 with 2a was carried out in the
2
presence of manganese(III) acetate under an argon atmos-
phere at 100°, the major products were found to be N,N'-
ethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-
carboxamide) (3 a) and N-(3-oxobutanamidoethyl)-2-
2
methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxamide

Nov-Dec 2005
A Facile Synthesis of N,N'-Oligomethylenebis(4,5-dihydrofuran-3-carboxamide)s
1339
amido hydrogen might be sensitive to the manganese(III)
oxidant under these conditions [6,8,39,45,49]. In order to
synthesize the compounds bearing two 1,2-dioxane skele-
tons [36], a mixture of N,N'-ethylenebis(3-oxobutanamide)
12 and 2a was oxidized with manganese(III) acetate under
a dry air stream at 23°, but our attempt failed. After work-
up, benzophenone (12%) and a complex mixture were
obtained.

1
340
F. A. Chowdhury and H. Nishino
Materials.
Vol. 42
Reaction Pathway.
Manganese(II) acetate tetrahydrate, Mn(OAc) •4H O, was
The formation of bis(dihydrofuran)s 3 a could be
2
2
n
purchased from Wako Pure Chemical Ind., Ltd. Manganese(III)
acetate dihydrate, Mn(OAc) •2H O, was prepared according to
explained on the basis of the mechanism outlined in
Scheme 4. It seemed that the formation of a new complex
A initiated the present reaction according to a similar
mechanism for the reaction with the 1,3-dicarbonyl com-
pounds [50-53]. We failed to isolate complex A from the
solution, however, manganese(III) acetate readily reacted
with 4,4,4-trifluoro-1-phenyl-1,3-butanedione to give
tris(4,4,4-trifluoro-1-phenyl-1,3-butanedionato)-man-
ganese(III) which was isolated and characterized [52].
Several alkenes were oxidized with the complex at reflux
temperature to give the corresponding 3-benzoyl-2-trifluo-
romethyl-4,5-dihydrofurans [52]. Based on the isolated
products, it was strongly suggested that complex A should
be formed during the first stage. The weak interaction
between complex A and alkene 2a, such as an electron
donor-acceptor (EDA) complex B [9], would induce a con-
certed one-electron transfer from the alkene to metal cen-
ter via the coordinated 1,3-dicarbonyl ligand to form the
3
2
the method described in the literature [55]. 1,1-Diarylethenes 2a-
d were prepared by dehydration of the corresponding alcohols
which were synthesized from substituted acetophenones and
arylmagnesium bromides.
Preparation of N,N'-Oligomethylenebis(3-oxobutanamide)
Derivatives 1 (n = 2-8), 5, and 7 [56-58].
n
Ethylenediamine (4g; 0.06 mmol) was placed in a 100 mL flask
equipped with a magnetic stirrer and a reflux condenser. Ethanol
50 mL) was added to the flask, which was placed in an ice bath,
and the mixture was stirred. Diketene (9.2 mL; 0.12 mmol) was
added dropwise with continuous stirring, and the reaction mixture
was allowed to stand for a few minutes at room temperature.
Needle-like crystals were immediately formed. The crude crys-
tals were then collected by filtration and washed with cold
ethanol. The crystals were then recrystallized from ethanol. N,N'-
Oligomethylenebis(3-oxobutanamide)s 1n (n = 2-8) and N,N'-
(
(
3,6-dioxaoctamethylene)bis(3-oxobutanamide) (7) were pre-
pared using the corresponding oligomethylenediamines and 1,2-
bis(2-aminoethoxy)ethane according to a method similar to that
mentioned above. However, in the case of 3-oxobutanamidoethyl
-oxobutanoate (5), acetonitrile instead of ethanol was used as the
solvent, and the reaction of 2-aminoethanol with diketene was car-
tertiary radical
C
during the second stage
[
7,9,11,15,16,22]. Under the reaction conditions, further
3
oxidation occurred and the mono(dihydrofuran) 4 a was
n
obtained via cyclization of the tertiary cation D. A similar
ried out at reflux temperature, producing 5 as a liquid. The physi-
reaction of 4 a with manganese(III) acetate was repeated
n
cal data of the compounds 1 (n = 2-8), 5, and 7 are given below.
n
to produce bis(dihydrofuran) 3 a.
n
N,N'-Ethylenebis(3-oxobutanamide) (12).
Conclusion.
This compound was obtained as colorless microcrystals (from
EtOH), mp 165°; ir (KBr) 3600-3100 (NH), 1730, 1645 (C=O);
A simple one-step synthesis of bis(dihydrofuran)s was
achieved by the reaction of N,N'-oligomethylenebis(3-
1
H nmr (DMSO-d ): δ 8.08 (2H, br t, J = 6.16, NH x 2), 3.28 (4H,
6
13
s, CH x 2), 3.13 (4H, m, NHCH x 2), 2.14 (6H, s, CH x 2);
C
oxobutanamide)s 1 and 7 with 1,1-diarylethenes 2 in the
2
2
3
n
NMR (DMSO-d ): δ 202.9 (C=O x 2), 166.2 (CON x 2), 51.2
presence of manganese(III) acetate. Butanamidoethyl 3-
oxobutanoate 5 has a higher selectivity for the formation of
6
(
CH x 2), 38.3 (CH x 2), 29.9 (CH x 2).
2 2 3
Anal. Calcd. for C10H16N O : C, 52.62; H, 7.07; N, 12.27.
2
4
bis(dihydrofuran) than 1 and 7. An increase in the methyl-
n
Found: C, 52.58; H, 7.24; N, 12.30.
ene chain length of 1 does not produce any dramatic
n
N,N'-Trimethylenebis(3-oxobutanamide) (13).
This compound was obtained as colorless microcrystals (from
EtOH), mp 138°; ir (KBr) 3600-3100 (NH), 1730, 1643 (C=O);
changes in the yields of the bis(4,5-dihydrofuran-3-carbox-
amide)s 3 , however, the present method would be conve-
n
nient and important since bis(dihydrofuran)s could be con-
verted into the corresponding synthons of the 1,3-dicar-
bonyl compounds [54] and bis(tetrahydrofuran)s which
construct part of the structure of many natural products.
1
H nmr (DMSO-d ) 8.02 (2H, br t, J = 6.16, NH x 2), 3.29 (4H, s,
6
CH x 2), 3.08 (4H, m, NHCH x 2), 2.14 (6H, s, CH x 2), 1.54
2
2
3
1
3
(
1
2H, m, -CH CH CH -); C nmr (DMSO-d ) 203.0 (C=O x 2),
2 2 2 6
65.9 (CON x 2), 51.2 (CH x 2), 36.4 (CH x 2), 29.9 (CH x 2),
2 2 3
2
8.9 (CH2).
Anal. Calcd. for C H N O : C, 54.53; H, 7.49; N, 11.56.
EXPERIMENTAL
11 18 2 4
Found: C, 54.27; H, 7.72; N, 11.54.
Measurements.
N,N'-Tetramethylenebis(3-oxobutanamide) (14).
All of the nmr spectra were recorded using a JNM-AL 300 FT
This compound was obtained as colorless microcrystals (from
EtOH), mp 145°; ir (KBr) 3600-3102 (NH), 1730, 1650 (C=O);
1
13
nmr spectrometer at 300 MHz for H and at 75 MHz for C with
tetramethylsilane as the internal standard. The chemical shifts are
shown in δ_ and coupling constants in Hz. The IR spectra were
measured using a Paragon 1000 FT ir spectrometer. The IR spec-
1
H nmr (DMSO-d ) 8.03 (2H, br t, J = 6.16, NH x 2), 3.28 (4H, s,
6
CH x 2), 3.06 (4H, m, NHCH x 2), 2.14 (6H, s, CH x 2), 1.52-
2
2
3
1
3
1.30 (4H, m, CH x 2); C nmr (DMSO-d ) 203.0 (C=O x 2),
2
6
-1
tral data are expressed in cm . All of the melting points were
determined using a Yanaco micromelting-point apparatus MP-J3
and are uncorrected. Elemental analysis was performed by the
Center of Instrumental Analysis, Kumamoto University, Japan.
165.8 (CON x 2), 51.3 (CH x 2), 38.2 (CH x 2), 29.9 (CH x 2),
2 2 3
26.4 (CH x 2).
2
Anal. Calcd. for C12H20N O : C, 56.23; H, 7.87; N, 10.93.
2
4
Found: C, 56.05; H, 8.09; N, 11.00.

Nov-Dec 2005
A Facile Synthesis of N,N'-Oligomethylenebis(4,5-dihydrofuran-3-carboxamide)s
1341
N,N'-Pentamethylenebis(3-oxobutanamide) (15).
(DMSO-d ) 203.9 (C=O x 2), 167.0 (CON x 2), 70.3 (CH x 2),
6 2
6
9.8 (CH x 2), 51.9 (CH x 2), 39.5 (CH x 2), 30.6 (CH x 2).
2 2 2 3
This compound was obtained as colorless microcrystals (from
EtOH), mp 130°; ir (KBr) 3600-3104 (NH), 1729, 1646 (C=O);
Anal. Calcd. for C14H24N O : C, 53.15; H, 7.65; N, 8.86.
2
6
Found: C, 52.93; H, 7.96; N, 8.83.
1
H nmr (DMSO-d ) 8.00 (2H, br t, J = 6.80, NH x 2), 3.28 (4H, s,
6
CH x 2), 3.04 (4H, m, NHCH x 2), 2.13 (6H, s, CH x 2), 1.56-
Manganese(III)-Based Reaction of N,N'-Oligomethylenebis(3-
oxobutanamide)s 1n (n = 2-8) with 1,1-Diarylethenes 2a-d at
Reflux Temperature.
2
2
3
1
3
1
1
2
.14 (6H, m, CH x 3); C nmr (DMSO-d ) 203.0 (C=O x 2),
2
6
65.7 (CON x 2), 51.3 (CH x 2), 38.4 (CH x 2), 29.9 (CH x 2),
2
2
3
8.5 (CH x 2), 23.6 (CH ).
2
2
N,N'-Oligomethylenebis(3-oxobutanamide) 1n (n = 2-8; 0.5-
Anal. Calcd. for C13H22N O : C, 57.76; H, 8.20; N, 10.36.
2
4
2
.0 mmol) and 1,1-diarylethene 2 (1.0-1.5 mmol) were placed in
Found: C, 57.64; H, 8.56; N, 10.37.
a 50 mL flask equipped with a magnetic stirrer. Glacial acetic
acid (25 mL) and manganese(III) acetate (2.5-4 mmol) were
added to the flask. The flask was fitted with a reflux condenser
and a gas inlet tube. The mixture was sufficiently degassed under
reduced pressure using an ultrasonicator in order to exchange
with an argon atmosphere, and then heated at 100° using an oil
bath with continuous stirring until the brown color of the Mn(III)
disappeared. The solvent was removed in vacuo and the residue
was triturated with water (50 mL). The aqueous reaction mixture
was next extracted with chloroform (20 mL x 3). The chloroform
extract was washed with saturated sodium hydrogen carbonate
solution (30 mL) and water (30 mL), dried over anhydrous
sodium sulfate, filtered, and concentrated to dryness. The prod-
ucts were separated by silica gel TLC (Wakogel B-10) using 2%
N,N'-Hexamethylenebis(3-oxobutanamide) (16).
This compound was obtained as colorless microcrystals (from
EtOH), mp 141°; ir (KBr) 3500-3100 (NH), 1729, 1650 (C=O);
1
H nmr (DMSO-d ) 8.01 (2H, br t, J = 6.71, NH x 2), 3.28 (4H,
6
s, CH x 2), 3.05 (4H, m, NHCH x 2), 2.14 (6H, s, CH x 2),
2
2
3
1
3
1
2
.56-1.15 (8H, m, CH x 4); C nmr (DMSO-d ) 203.0 (C=O x
2 6
), 165.8 (CON x 2), 51.3 (CH x 2), 38.5 (CH x 2), 29.8 (CH
3
2
2
x 2), 28.9 (CH x 2), 26.0 (CH x 2).
2
2
Anal. Calcd. for C14H24N O : C, 59.13; H, 8.51; N, 9.85.
2
4
Found: C, 59.07; H, 8.59; N, 9.97.
N,N'-Heptamethylenebis(3-oxobutanamide) (17).
This compound was obtained as colorless microcrystals (from
EtOH), mp 138°; ir (KBr) 3500-3100 (NH), 1729, 1649 (C=O);
MeOH-CHCl as the developing solvent. The yields are listed in
3
1
Tables 1and 2. The products were further purified by recrystal-
lization to obtain the analytical samples. The physical properties,
which were obtained in the pure state, are listed below.
H nmr (CDCl ) 7.03 (2H, br t, J = 6.71, NH x 2), 3.41 (4H, s,
3
CH x 2), 3.05 (4H, m, NHCH x 2), 2.27 (6H, s, CH x 2), 1.53-
2
2
3
1
3
1
1
2
.32 (10H, m, CH2 x 5); C nmr (CDCl ) 204.9 (C=O x 2),
3
65.4 (CON x 2), 49.6 (CH x 2), 39.3 (CH x 2), 31.0 (CH x 2),
2
2
3
N,N'-Ethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-
9.1 (CH x 2), 28.5 (CH ), 26.5 (CH x 2).
2
2
2
carboxamide) (3 a).
2
Anal. Calcd. for C15H26N O : C, 60.38; H, 8.78; N, 9.39.
2
4
This compound was obtained as colorless microcrystals (from
Found: C, 60.29; H, 9.15; N, 9.36.
CHCl -hexane); mp 246°; ir (KBr) 3600-3100 (NH), 1667
3
N,N'-Octamethylenebis(3-oxobutanamide) (18).
(C=O); H nmr (CDCl ) 7.36-7.23 (20H, m, arom H), 6.48 (2H,
1
3
br t, J = 6.16, 2 x NH), 3.53 (4H, s, CH x 2), 3.37 (4H, m,
This compound was obtained as colorless microcrystals (from
EtOH), mp 144°; ir (KBr) 3600-3100 (NH), 1729, 1644 (C=O);
2
1
3
NHCH2 x 2), 2.31 (6H, s, CH3 x 2); C nmr (CDCl ) 167.0
3
1
(C=O x 2), 163.9 (O-C= x 2), 145.1 (4C) (arom C), 128.3 (8C),
H nmr (DMSO-d ) 8.00 (2H, br t, J = 6.71, NH x 2), 3.27 (4H, s,
6
1
27.5 (4C), 125.6 (8C) (arom CH), 102.5 (>C= x 2), 90.8 (>C-O
CH x 2), 3.05 (4H, m, NHCH x 2), 2.13 (6H, s, CH x 2), 1.39-
2
2
3
1
3
x 2), 44.2 (CH x 2), 40.3 (CH x 2), 13.9 (CH x 2).
1
1
2
.25 (12H, m, CH x 6); C NMR (DMSO-d ) 203.0 (C=O x 2),
2
2
3
2
6
65.7 (CON x 2), 51.3 (CH x 2), 38.5 (CH x 2), 29.8 (CH x 2),
Anal. Calcd. for C38H36N2O4: C, 78.06; H, 6.21; N, 4.79.
Found: C, 77.76; H, 6.28; N, 4.84.
2
2
3
8.9 (CH x 2), 28.6 (CH x 2), 26.2 (CH x 2).
2
2
2
Anal. Calcd. for C16H28N O : C, 61.51; H, 9.03; N, 8.97.
Found: C, 61.33; H, 8.83; N, 8.98.
2
4
N,N'-Ethylenebis[5,5-bis(4-chlorophenyl)-2-methyl-4,5-dihy-
drofuran-3-carboxamide] (3 b).
2
3
-Oxobutanamidoethyl 3-Oxobutanoate (5).
This compound was obtained as colorless microcrystals (from
CHCl3-hexane); mp 256°; ir (CHCl3) 3600-3100 (NH), 1668
This compound was obtained as yellow liquid; ir (CDCl )
3
1
(C=O); 1H nmr (CDCl ) 7.40-7.20 (16H, m, arom H), 6.57 (2H,
3
600-3100 (NH), 1746, 1669 (C=O); H nmr (CDCl ) 7.44 (1H,
3
3
br t, J = 5.37, NH), 4.25 (2H, t, J = 5.37, OCH ), 3.55 (2H, m,
NHCH ), 3.54 (2H, s, CH ), 3.43 (2H, s, CH ), 2.28 (3H, s,
CH ), 2.26 (3H, s, CH ); C nmr (CDCl ) 203.8, 201.4 (C=O x
br t, J = 6.16, NH x 2), 3.46 (4H, m, CH2 x 2), 3.34 (4H, m,
2
1
3
NHCH2 x 2), 2.29 (6H, s, CH3 x 2); C nmr (CDCl3) 166.7
(C=O x 2), 163.5 (O-C= x 2), 143.1 (4C), 133.7 (4C) (arom C),
128.6 (8C), 127.0 (8C) (arom CH), 102.6 (>C= x 2), 89.8 (>C-O
x 2), 44.0 (CH2 x 2), 40.5 (CH2 x 2), 13.9 (CH3 x 2).
Anal. Calcd. for C38H32N2O4Cl4: C, 63.17; H, 4.46; N, 3.88.
Found: C, 62.87; H, 4.51; N, 4.01.
2
2
2
1
3
3
3
3
2
), 167.1, 166.6 (C=O), 63.5, 50.4, 49.9, 38.3 (CH ), 30.6 (CH ),
2 3
3
0.3 (CH3).
Anal. Calcd. for C10H15NO •1/4H O: C, 51.39; H, 6.47; N,
5
2
5
.99. Found: C, 51.07; H, 6.65; N, 6.11.
N,N'-(3,6-Dioxaoctamethylene)bis(3-oxobutanamide) (7).
N,N'-Ethylenebis[5,5-bis(4-methylphenyl)-2-methyl-4,5-dihy-
drofuran-3-carboxamide] (3 c).
2
This compound was obtained as colorless microcrystals (from
EtOH), mp 84°; ir (KBr) 3600-3000 (NH), 1729, 1644 (C=O); H
1
This compound was obtained as colorless microcrystals
NMR (DMSO-d ) 8.12 (2H, br t, J = 5.86, NH x 2), 3.53 (4H, s,
(from CH Cl -hexane); mp 270°; ir (CHCl ) 3700-3000 (NH),
1665 (C=O); H nmr (CDCl ) 7.23-7.07 (16H, m, arom H),
3
6
2 2 3
1
CH x 2), 3.44 (4H, t, J = 5.86, CH x 2), 3.33 (4H, s, CH x 2),
2
2
2
1
3
2
.26 (4H, t, J = 5.86, CH x 2), 2.15 (6H, s, CH x 2); C nmr
6.53 (2H, br t, J = 6.16, NH x 2), 3.49 (4H, m, CH x 2), 3.33
2
3
2

1342
F. A. Chowdhury and H. Nishino
Vol. 42
(
4H, m, NHCH x 2), 2.30 (6H, s, CH x 2), 2.29 (12H, s, CH
Anal. Calcd. for C41H42N O : C, 78.57; H, 6.75; N, 4.47.
2 4
Found: C, 78.37; H, 6.84; N, 4.58.
2
3
3
1
3
x 4); C nmr (CDCl ) 167.1 (C=O x 2), 163.8 (O-C= x 2),
3
1
42.4 (4C), 137.1 (4C) (arom C), 128.9 (8C), 125.6 (8C) (arom
N,N'-Hexamethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofu-
CH), 102.4 (>C= x 2), 90.7 (>C-O x 2), 44.1 (CH x 2), 40.4
2
ran-3-carboxa-mide) (3 a).
6
(
CH x 2), 21.0 (CH x 4), 14.0 (CH x 2).
2 3 3
Anal. Calcd. for C42H44N O : C, 78.72; H, 6.92; N, 4.37.
This compound was obtained as colorless microcrystals (from
2
4
Found: C, 78.45; H, 7.10; N, 4.45.
CH2Cl2-hexane); mp 218-220°; ir (KBr) 3700-3100 (NH), 1669
1
(
C=O); H nmr (CDCl ) 7.39-7.21 (20H, m, arom H), 5.50 (2H,
3
N,N'-Ethylenebis[5,5-bis(4-methoxylphenyl)-2-methyl-4,5-dihy-
dro-furan-3-carboxamide] (3 d).
br t, J = 6.71, NH x 2), 3.53 (4H, m, CH x 2), 3.22 (4H, m,
2
2
NHCH x 2), 2.36 (6H, s, CH x 2), 1.48-1.43 (4H, m, CH x 2),
2
3
2
1
3
This compound was obtained as colorless microcrystals (from
1.30-1.28 (4H, m, CH x 2); C NMR (CDCl ) 165.5 (C=O x 2),
2 3
CH Cl -hexane); mp 281°; ir (CHCl ) 3700-3000 (NH), 1665
163.3 (O-C= x 2), 145.2 (4C) (arom C), 128.3 (8C), 127.5 (4C),
125.6 (8C) (arom CH), 102.6 (>C= x 2), 90.5 (>C-O x 2), 44.6
2
2
3
1
(
C=O); H nmr (CDCl ) 7.25-6.80 (16H, m, arom H), 6.63 (2H,
3
br t, J = 6.16, NH x 2), 3.75 (12H, s, OCH x 2), 3.48 (4H, m,
(CH x 2), 38.8 (CH x 2), 29.6 (CH x 2), 26.1 (CH x 2), 14.0
(CH x 2).
3
3
2 2 2 2
1
3
CH x 2), 3.33 (4H, m, NHCH x 2), 2.30 (6H, s, CH x 2);
C
2
2
3
nmr (CDCl ) 167.1 (C=O x 2), 163.7 (O-C= x 2), 158.8 (4C),
Anal. Calcd. for C42H44N O : C, 78.72; H, 6.92; N, 4.37.
3
2 4
137.5 (4C) (arom C), 127.0 (8C), 113.6 (8C) (arom CH), 102.4
Found: C, 78.61; H, 7.06; N, 4.29.
(
4
>C= x 2), 90.5 (>C-O x 2), 55.2 (OCH x 4), 44.3 (CH x 2),
0.4 (CH x 2), 14.0 (CH x 2).
2 3
3
2
N,N'-Heptamethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofu-
ran-3-carboxamide) (3 a).
7
Anal. Calcd. for C42H44N O : C, 71.57; H, 6.29; N, 3.97.
2
8
Found: C, 71.49; H, 6.37; N, 3.95.
This compound was obtained as colorless microcrystals (from
CH Cl -hexane); mp 234-236°; ir (KBr) 3600-3000 (NH), 1669
2
2
N,N'-Trimethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofuran-
3
1
(
C=O); H nmr (CDCl ) 7.39-7.21 (20H, m, arom H), 5.34 (2H,
3
-carboxamide) (3 a).
3
br t, J = 6.71, NH x 2), 3.52 (4H, m, CH x 2), 3.22 (4H, m,
2
This compound was obtained as colorless microcrystals (from
NHCH x 2), 2.37 (6H, s, CH x 2), 1.48-1.43 (4H, m, CH x 2),
1.27 (6H, s, CH x 3); C nmr (CDCl ) 165.5 (C=O x 2), 163.3
2 3
2 3 2
1
3
CHCl -hexane); mp 268°; ir (KBr) 3600-3100 (NH), 1667
3
1
(
C=O); H nmr (CDCl ) 7.38-7.19 (20H, m, arom H), 6.42 (2H,
(O-C= x 2), 145.2 (4C) (arom C), 128.3 (8C), 127.5 (4C), 125.6
(8C) (arom CH), 102.6 (>C= x 2), 90.5 (>C-O x 2), 44.6 (CH x
3
br t, J = 6.16, NH x 2), 3.59 (4H, m, CH x 2), 3.26 (4H, m,
2
2
NHCH x 2), 2.37 (6H, s, CH x 2), 1.54 (2H, m, -CH CH CH -
2), 39.2 (CH x 2), 29.7 (CH x 2), 28.9 (CH ), 26.8 (CH x 2),
14.0 (CH x 2).
3
2
3
2
2
2
2 2 2 2
13
)
(
;
C nmr (CDCl ) 166.1 (C=O x 2), 163.4 (O-C= x 2), 145.2
3
4C) (arom C), 128.3 (8C), 127.5 (4C), 125.6 (8C) (arom CH),
Anal. Calcd. for C43H46N O : C, 78.87; H, 7.08; N, 4.28.
2 4
1
02.8 (>C= x 2), 90.6 (>C-O x 2), 44.3 (CH x 2), 35.2 (CH x
Found: C, 78.93; H, 7.11; N, 4.40.
2
2
2
), 29.9 (CH ), 14.0 (CH x 2).
2
3
N,N'-Octamethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofu-
Anal. Calcd. for C39H38N O : C, 78.24; H, 6.40; N, 4.68.
2
4
ran-3-carboxamide) (3 a).
8
Found: C, 78.02; H, 6.55; N, 4.79.
This compound was obtained as colorless microcrystals (from
N,N'-Tetramethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofu-
ran-3-carboxamide) (3 a).
CH Cl -hexane); mp 218°; ir (KBr) 3600-3000 (NH), 1667
2
2
4
1
(
C=O); H nmr (CDCl ) 7.39-7.25 (20H, m, arom H), 5.25 (2H,
3
This compound was obtained as colorless microcrystals (from
br t, J = 6.71, NH x 2), 3.52 (4H, m, CH x 2), 3.24 (4H, m,
2
CH Cl -hexane); mp 237-240°; ir (KBr) 3600-3100 (NH), 1668
NHCH x 2), 2.38 (6H, s, CH x 2), 1.49-1.44 (4H, m, CH x 2),
2 3 2
2
2
1
13
(
C=O); H nmr (CDCl ) 7.38-7.22 (20H, m, arom H), 5.74 (2H,
1.27 (8H, s, CH x 4); C nmr (CDCl ) 165.5 (C=O x 2), 163.3
3
2 3
br t, J = 6.16, NH x 2), 3.54 (4H, m, CH x 2), 3.25 (4H, m,
(O-C= x 2), 145.2 (4C) (arom C), 128.3 (8C), 127.6 (4C), 125.7
(8C) (arom CH), 102.5 (>C= x 2), 90.5 (>C-O x 2), 44.7 (CH x
2
1
3
NHCH x 2), 2.35 (6H, s, CH x 2), 1.49 (4H, m, CH x 2);
C
2
3
2
2
nmr (CDCl ) 165.7 (C=O x 2), 163.4 (O-C= x 2), 145.2 (4C)
2), 39.3 (CH x 2), 29.8 (CH x 2), 29.1 (CH x 2), 26.9 (CH x
3
2 2 2 2
(
(
(
arom C), 128.3 (8C), 127.5 (4C), 125.6 (8C) (arom CH), 102.6
>C= x 2), 90.6 (>C-O x 2), 44.5 (CH x 2), 38.7 (CH x 2), 27.0
2), 14.0 (CH x 2).
3
Anal. Calcd. for C44H48N O : C, 79.01; H, 7.23; N, 4.19.
Found: C, 78.94; H, 7.27; N, 4.36.
2
2
2 4
CH x 2), 14.0 (CH x 2).
2
3
Anal. Calcd. for C40H40N O : C, 78.40; H, 6.58; N, 4.57.
Found: C, 78.42; H, 6.65; N, 4.73.
2
4
N-3-Oxobutanamidoethyl-2-methyl-5,5-diphenyl-4,5-dihydrofu-
ran-3-carboxamide (4 a).
2
N,N'-Pentamethylenebis(2-methyl-5,5-diphenyl-4,5-dihydrofu-
This compound was obtained as colorless microcrystals (from
ran-3-carboxamide) (3 a).
5
CHCl -hexane); mp 139°; ir (CDCl ) 3600-3100 (NH), 1715,
3
3
1
This compound was obtained as colorless microcrystals (from
1666 (C=O); H nmr (CDCl ) 7.60 (1H, br t, J = 6.16, NH), 7.39-
3
CH Cl -hexane); mp 225°; ir (KBr) 3600-3100 (NH), 1668
7.23 (10H, m, arom H), 6.38 (1H, br t, J = 6.16, NH), 3.55 (2H,
2
2
1
(
C=O); H nmr (CDCl ) 7.38-7.24 (20H, m, arom H), 5.33 (2H, br
m, CH ), 3.36-3.33 (6H, m, CH , NHCH x 2), 2.35 (3H, s,
3
2 2 2
1
3
t, J = 6.80, NH x 2), 3.51 (4H, s, 2 x CH ), 3.23 (4H, m, NHCH
CH ), 2.14 (3H, s, CH ); C nmr (CDCl ) 203.5, 167.5, 166.4
3 3 3
2
2
x 2), 2.36 (6H, s, CH x 2), 1.54-1.44 (4H, m, CH x 2), 1.32-1.30
(C=O), 163.7 (O-C=), 145.1 (2C) (arom C), 128.3 (4C), 127.5
(2C), 125.7 (4C) (arom CH), 102.6 (>C=), 90.8 (>C-O), 50.3,
3
2
(
2H, m, CH2); 13C nmr (CDCl ) 165.6 (C=O x 2), 163.4 (O-C= x
3
2), 145.1 (4C) (arom C), 128.3 (8C), 127.5 (4C), 125.6 (8C) (arom
44.1 40.0, 39.6 (CH ), 30.5, 14.0 (CH ).
2 3
CH), 102.5 (>C= x 2), 90.5 (>C-O x 2), 44.6 (CH x 2), 39.0 (CH
Anal. Calcd. for C24H26N O : C, 70.92; H, 6.45; N, 6.89.
2
2
2 4
x 2), 29.5 (CH x 2), 24.3 (CH ), 14.0 (CH x 2).
Found: C, 70.63; H, 6.60; N, 6.89.
2
2
3

Nov-Dec 2005
A Facile Synthesis of N,N'-Oligomethylenebis(4,5-dihydrofuran-3-carboxamide)s
1343
(
2-Methyl-5,5-diphenyl-4,5-dihydrofuran-3-amido)ethyl 2-
(1984).
18] E. J. Corey and A. W. Gross, Tetrahedron Lett., 26, 4291
1985).
[
Methyl-5,5-diphenyl-4,5-dihy- drofuran-3-carboxylate (6).
(
This compound was obtained as colorless microcrystals (from
[
19] E. J. Corey and A. K. Ghosh, Chem. Lett., 223 (1987).
CH Cl -hexane); mp 99°; ir (KBr) 3500-3000 (NH), 1671, 1647
2
2
[20] E. J. Corey and A. K. Ghosh, Tetrahedron Lett., 28, 175
1
(C=O); H nmr (CDCl ) 7.36-7.21 (20H, m, arom H), 5.88 (1H,
(1987).
[21] M. Okano, Bull. Chem. Soc. Jpn., 49, 1041 (1976).
[22] A. Citterio, R. Santi, T. Fiorani, and S. Strologo, J. Org.
Chem., 54, 2703 (1989).
3
br t, J = 5.37, NH), 4.21 (2H, t, J = 5.37, OCH ), 3.58-3.50 (6H,
m, CH2 x 3), 2.35 (3H, s, CH ), 2.30 (3H, s, CH ); C nmr
(
1
(
(
2
1
3
3
3
CDCl ) 167.4, 165.5 (C=O), 166.1, 163.5 (O-C=), 145.1 (2C),
3
[
23] A. Citterio, D. Fancelli, C. Finzi, L. Pesce, and R. Santi, J.
Org. Chem., 54, 2713 (1989).
24] A. Citterio, R. Sebastiano, A. Marion, and R. Santi, J. Org.
44.9 (2C) (arom C), 128.3 (8C), 127.6 (2C), 127.5 (2C), 125.6
4C), 125.5 (4C), (arom CH), 102.5, 101.2 (>C=), 91.8, 90.6
>C-O), 62.3, 44.4, 44.0, 39.2 (CH ), 14.3, 13.9 (CH ).
[
2
3
Chem., 56, 5328 (1991).
Anal. Calcd. for C38H35NO •1/4H O: C, 77.33; H, 5.98; N,
5
2
[25] D. T. Davies, N. Kapur, and A. F. Parsons, Tetrahedron, 56,
2
.37. Found: C, 77.33; H, 6.20; N, 2.68.
3
941 (2000).
[
26] G. Bar, A. F. Parsons, and C. B. Thomas, Tetrahedron Lett.,
N,N'-(3,6-Dioxaoctamethylene)bis(2-methyl-5,5-diphenyl-4,5-
dihydrofuran-3-carboxamide) (8).
4
1, 7751 (2000).
[
27] G. Bar, A. F. Parsons, and C. B. Thomas, Chem. Commun,
This compound was obtained as colorless microcrystals (from
1350 (2001).
[
28] G. Bar, A. F. Parsons, and C. B. Thomas, Tetrahedron, 57,
CH Cl -hexane); mp 166°; ir (KBr) 3600-3000 (NH), 1669
2
2
1
4719 (2001).
(
C=O); H nmr (CDCl ) 7.38-7.22 (20H, m, arom H), 5.83 (2H,
3
[
[
29] C.-P. Chuang and S.-F. Wang, Tetrahedron, 54, 10043 (1998).
30] C.-P. Chuang, Y.-L. Wu, and M.-C. Jiang, Tetrahedron, 55,
br t, J = 5.86, NH x 2), 3.54 (4H, s, CH x 2), 3.51 (4H, t, J =
2
5
.86, CH x 2), 3.44 (4H, t, J = 5.86, CH x 2), 3.39 (4H, s, CH
2 2 2
1
1229 (1999).
[31] Y.-L. Wu, C.-P. Chuang, and P.-Y. Lin, Tetrahedron, 56, 6209
2000).
32] C.-P. Chuang and Y.-L. Wu, Tetrahedron Lett., 42, 1717
(2001).
[33] A.-I, Tsai, Y.-L. Wu, and C.-P. Chuang, Tetrahedron, 57, 7829
(2001).
1
3
x 2), 2.38 (6H, s, CH x 2); C nmr (CDCl ) 165.6 (C=O x 2),
3
3
1
1
(
63.6 (O-C= x 2), 145.1 (4C) (arom C), 128.3 (8C), 127.5 (4C),
25.6 (8C) (arom CH), 102.6 (>C= x 2), 90.6 (>C-O x 2), 70.0
(
[
CH x 2), 44.4 (CH x 2), 38.9 (CH x 2), 14.0 (CH x 2).
2 2 2 3
Anal. Calcd. for C42H44N O •1/4H O: C, 74.49; H, 6.55; N,
2
6
2
4
.14. Found: C, 74.43; H, 6.60; N, 4.08.
[
34] H. Nishino, T. Yoshida, and K. Kurosawa, Bull. Chem. Soc.
Jpn., 64, 1097 (1991).
REFERENCES AND NOTES
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[
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(2004).
*
Corresponding author. e-mail: nishino@sci.kumamoto-
u.ac.jp; Tel.: +81-96-342-3374; fax: +81-96-342-3374;
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[
[
[
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[
[
[
[
[
[
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[
[
[
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[
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[
[
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(
(
1974).
[
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[
[
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[

1344
F. A. Chowdhury and H. Nishino
Vol. 42
[
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