Syntheses of ethyl 2,5-diarylfuran-3-carboxylates and methyl 5-aryl-4- (ω-hydroxyalkyl)-2-methylfuran-3-carboxylates

Article abstract of DOI:10.1055/s-1998-4498

Acid-catalyzed reaction of ethyl 3,6,6-triaryl-3-hydroxy-1,2-dioxane-4- carboxylates yielded ethyl 2,5-diarylfuran-3-carboxylates in 18-40% yield. The reaction of methyl 4-hydroxy-2,3-dioxabicyclo[n.4.0]alkane-5-carboxylates gave methyl 5-aryl-4-(ω-hydroxyalkyl)-2-methylfuran-3-carboxylates in 59- 71% yields.

Full text of DOI:10.1055/s-1998-4498

SYNTHESIS
October 1998
1457
Syntheses of Ethyl 2,5-Diarylfuran-3-carboxylates and Methyl 5-Aryl-4-(ω-
hydroxyalkyl)-2-methylfuran-3-carboxylates
Shougo Kajikawa,a Yoshikazu Noiri,b Hidenari Shudo,b Hiroshi Nishino,b Kazu Kurosawa*c
a Department of Environmental Science, Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1,
Kumamoto 860-8555, Japan
b Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan
c Department of Environmental Science, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan
Fax +81(96)342-3320; E-mail: kurosawa@aster.sci.kumamoto-u.ac.jp
Received 17 November 1997; revised 16 January 1998
Abstract: Acid-catalyzed reaction of ethyl 3,6,6-triaryl-3-
hydroxy-1,2-dioxane-4-carboxylates yielded ethyl 2,5-diaryl-
furan-3-carboxylates in 18–40% yield. The reaction of methyl
The reactions of 1-phenylcyclohexene (1d) with 2d gave
methyl 4-hydroxy-4-methyl-1-phenyl-2,3-dioxabicyc-
lo[4.4.0]decane-5-carboxylate (3dd) as the major product
and 2-acetoxy-1-phenylcyclohexanol (4d). Similarly, 1-
(4-chlorophenyl)cyclohexene (1e), 1-(4-methyphenyl)cy-
clohexene (1f), and 1-phenylcycloheptene (1g) yielded
the corresponding bicyclic peroxides 3ed, 3fd, and 3gd in
moderate yields.
4-hydroxy-2,3-dioxabicyclo[n.4.0]alkane-5-carboxylates
gave
methyl 5-aryl-4-(ω-hydroxyalkyl)-2-methylfuran-3-carboxylates
in 59–71% yields.
Key words: manganese(III) acetate, cyclic peroxides, 2,3,5-tri-
and 2,3,4,5-tetrasubstituted furans
Although various synthetic routes are available for the
construction of the furan ring system, some syntheses of
substituted furans have still been carried out,1, 2 since they
are one of the key structures in natural products.3 It
seemed, however, that these syntheses were designed for
either monosubstituted furans or 2,3-di- and 2,3,5-trisub-
stituted furans, but the synthesis of tetrasubstituted furans
was rare limited to a single case.4 In previous studies,5–13
many cyclic peroxides bearing a 1,2-dioxane ring struc-
ture were synthesized using the reactions of alkenes with
active methylene compounds and atmospheric oxygen in
the presence of manganese(II and III) acetates in acetic
acid at room temperature. This was the first example that
molecular oxygen is trapped during the manganese(II and
III)-induced intermolecular radical cyclization reaction. It
was also demonstrated that reactions of the 1,2-dioxan-3-
ols bearing various substituent groups gave 2,3,5-trisub-
stituted furans in acid-catalyzed decomposition in excel-
lent yields.11 However, alkyl 3-aryl-3-oxopropanoates
and 1,1,2-trisubstituted ethenes were seldom used be-
cause of their low reactivity in the intermolecular free-
radical cyclization reaction. We investigated the possibil-
ity of forming 2,5-diarylfurans and 2,3,4,5-tetrasubstitut-
ed furans by using acid-catalyzed reactions of the corre-
sponding 1,2-dioxan-3-ols, which is described in this pa-
per.
When the reaction of 1,1-diarylethenes 1 with ethyl 3-
aryl-3-oxopropanoates 2 in the presence of a mixture of
manganese(II) and manganese(III) acetates was carried
out at room temperature with air bubbling through the re-
action mixture, it gave cyclic peroxides, the structure of
which was determined on the basis of 1H and 13C NMR,
IR spectra and elemental analysis. The reactions were ex-
amined for 1,1-diphenylethene (1a), 1,1-bis(4-chloro-
phenyl)-ethene (1b), 1,1-bis(4-methylphenyl)ethene (1c),
ethyl 3-(4-chlorophenyl)-3-oxopropanoate (2b), ethyl 3-
(4-methylphenyl)-3-oxopropanoate (2c), and methyl 3-
oxobutanoate (2d). The results are summarized in Table 1.
Scheme 1
The reaction of 1-phenylcyclopentene (1h) yielded meth-
yl 2-(4-hydroxy-4-phenyl-2,3-dioxacycloheptyl)-3-oxo-
butanoate (3hd) (Scheme 2). The IR spectrum of 3hd
showed the presence of two carbonyl groups at ν = 1738
and 1685 cm–1; The 13C NMR spectrum (CDCl3,

SYNTHESIS
Yield (%)b
Papers
1458
Table 1. Reactions of Ethyl 3-Aryl-3-oxopropanoates with 1,1-Di-
arylethenes or 1-Arylcycloalkenes in the Presence of Manganese(III)
Acetate and Molecular Oxygena
Table 2. Acid-Catalyzed Decomposition of Peroxidesa
Entry
Substrate
Product
Entry
Substrate
Alkene
Product (Yield [%])c
1
2
3
4
5
6
7
8
9
10
11
12
13
14c
3aa
3ab
3ac
3ba
3bb
3bc
3ca
3cb
3cc
3dd
3ed
3fd
3gd
3dd
5aa
5ab
5ac
5ba
5bb
5bc
5ca
5cb
5cc
5dd
5ed
5fd
5gd
6dd
32
22
21
23
20
24
40
18
35
64
71
59
62
74
β-Oxo Ester
1
2
3
4
5
6
7
8
9
1a
1a
1a
1b
1b
1b
1c
1c
1c
1d
1e
1f
2a
2b
2c
2a
2b
2c
2a
2b
2c
2d
2d
2d
2d
3aa (36)
3ab (71)
3ac (57)
3ba (29)
3bb (66)
3bc (54)
3ca (40)
3cb (74)
3cc (59)
3dd (24)
3ed (30)
3fd (21)
3gd (51)
–
–
–
–
–
–
–
–
–
10b
11b
12b
13b
4d (29)
4e (25)
4f (18)
4g (14)
a
These reactions were carried out in MeCN containing HClO4 for
15 min at reflux temperature.
Isolated yields based on the amount of the peroxide used.
The reaction was carried out in HOAc containing HClO4.
1g
b
c
a Alkene:β-oxo ester:Mn(OAc)2:Mn(OAc)3=1:3:1:0.1.
b Cycloalkene:methyl 3-oxobutanoate:Mn(OAc)3=1:3:1.
c Isolated yields based on the amount of alkene used.
122.0, and 114.1 corresponding to a phenyl group and a fu-
ran ring, a methoxy group at δ = 51.2, four methylenes at
δ = 62.0, 32.3, 26.3, and 23.8, and a methyl group at δ =
14.7. The signal at δ = 62.0 suggests the presence of a me-
thylene group attached to an oxygen function. Thus, the
structure of 5dd was determined as methyl 4-(4-hy-
droxybutyl)-2-methyl-5-phenylfuran-3-carboxylate. There
were other products which could not be identified because
of a failure in obtaining pure samples. Compound 6dd ob-
tained in the reactions in acetic acid exhibited a 13C NMR
spectrum similar to that of 5dd except for the presence of
an additional acetoxy group at δ = 171.1 and 21.0, indi-
cating that the compound is methyl 4-(4-acetoxybutyl)-2-
methyl-5-phenylfuran-3-carboxylate (6dd) (Scheme 1). As
it seems possible that 6dd was formed by the esterification
of 5dd with acetic acid, then 5dd was treated with acetic
acid. This resulted in the identical methyl 4-(4-acetoxy-
butyl)-2-methyl-5-phenylfuran-3-carboxylate. Thus, the
acid-catalyzed decomposition reaction could not give the
desired hydrobenzofurans, but gave furans with four sub-
stituent groups at the C-1~4 positions.
100 MHz) of 3hd also showed a ketonic carbonyl at δ =
199.7 and an ester carbonyl group at δ = 169.3. The pres-
ence of three methylenes at δ = 37.7, 33.9 and 20.2, a car-
bon bearing no hydrogen at δ = 104.8, and two methine
carbons at δ = 82.7 and 67.1 in the 13C NMR spectrum
would indicate the structure of 3hd as shown. The ring
strain in a cyclopentane may cause the formation of the
seven-membered peroxide. However, the mechanism for
the formation of 3hd is not clear.
Scheme 2
Acid-catalyzed decomposition of ethyl 3,6,6-triaryl-3-hy-
droxy-1,2-dioxane-4-carboxylates was carried out in ace-
tonitrile containing a trace amount of 60% perchloric acid.
This reaction of 3aa resulted in ethyl 2,5-diphenylfuran- A plausible mechanism for the formation of 5dd from 3dd
3-carboxylate (5aa). The reactions were examined for was advanced (Scheme 3) that was in accord with the
other 1,2-dioxane-4-carboxylates 3ab–cc that gave the mechanisms described for the case of 2,5-disubstituted 3-
corresponding trisubstituted furans 5ab–cc in moderate to furancarboxylates.11 The migration of the methylene
good yields (Table 2).
group of the cycloalkane ring has been observed in the
reaction of 1-phenylcyclopentylhydroperoxide with
acid14 that gave 4-oxo-5-phenylpentyl acetate as a minor
product (12%) along with cyclopentanone (60–65%), 1-
phenylcyclopentene (11%) and 1-phenylpentan-1-one
(3%). However, the migration of the methylene group of
the cycloalkane ring was observed for the first time in the
transformation of 1,2-dioxan-3-ols to furans.
It seemed that these results would indicate the possibility
of synthesizing bicyclic furans by the acid-catalyzed de-
composition of alkyl 4-hydroxy-2,3-dioxabicyclo[n.4.0]-
alkane-5-carboxylates. The acid-catalyzed decomposition
of methyl 4-hydroxy-4-methyl-1-phenyl-2,3-dioxabicy-
clo[4.4.0]decane-5-carboxylate (3dd) was also conducted
in acetonitrile under reflux for 15 minutes. The 13C NMR
spectrum of the product 5dd obtained in the reaction In conclusion, ethyl 2,5-diarylfuran-3-carboxylates were
showed the presence of a carbonyl group at δ = 165.1, synthesized by the acid-catalyzed decomposition of ethyl
eight peaks at δ = 158.9, 147.9, 130.9, 128.6, 127.5, 126.1, 3,6,6-triaryl-3-hydroxy-1,2-dioxane-4-carboxylates
in

SYNTHESIS
October 1998
1459
1H NMR (CDCl3, 60 MHz): δ = 7.83–7.13 (15H, m), 4.83–4.30 (1H,
br s), 3.97 (2H, q, J = 7 Hz), 3.17–2.90 (3H, m), 0.97 (3H, t, J = 7 Hz).
Ethyl 3-(4-Chlorophenyl)-3-hydroxy-6,6-diphenyl-1,2-dioxane-4-
carboxylate (3ab): mp 174–175°C (benzene).
IR (KBr): ν = 3405, 1718 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.85–7.21 (14H, m), 4.80 (1H, br s),
3.98 (2H, q, J = 7 Hz), 3.27–2.94 (3H, m), 0.97 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 171.6, 142.6, 140.5, 137.5, 135.1,
128.7 (2C), 128.4 (2C), 128.3 (4C), 127.2 (2C), 127.6 (2C), 126.9,
126.0, 99.1, 85.5, 61.3, 46.1, 32.3, 13.8.
Anal. Calcd for C25H23ClO5: C, 68.41; H, 5.28. Found: C, 68.51; H,
5.29.
Ethyl 3-Hydroxy-3-(4-methylphenyl)-6,6-diphenyl-1,2-dioxane-4-
carboxylate (3ac): mp 155–156°C (benzene).
IR (KBr): ν = 3407, 1717 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.80–7.10 (14H, m), 4.66 (1H, br s),
3.96 (2H, q, J = 7 Hz), 3.30–2.90 (3H, m), 2.23 (3H, s), 0.92 (3H, t, J
= 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 172.0, 142.8, 140.7, 139.0, 135.9,
129.3, 128.8 (2C), 128.6 (2C), 128.4 (2C), 128.3 (2C), 128.1, 126.1
(2C), 125.9 (2C), 99.4, 85.3, 61.2, 46.0, 32.5, 21.2, 13.8.
Anal. Calcd for C26H26O5: C, 74.62; H, 6.26. Found: C, 74.74; H,
6.25.
Scheme 3
moderate yields. The acid-catalyzed decomposition
of methyl
1-aryl-4-hydroxy-4-methyl-2,3-dioxabicy-
clo[n.4.0]alkane-5-carboxylates gave new methyl 5-aryl-
4-(ω-hydroxyalkyl)-2-methylfuran-3-carboxylates.
Ethyl 6,6-Bis(4-chlorophenyl)-3-hydroxy-3-phenyl-1,2-dioxane-4-
carboxylate (3ba): mp 185–186°C (benzene).
IR (KBr): ν = 3400, 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.60–7.02 (13H, m), 4.47 (1H, br s),
3.84 (2H, q, J = 7 Hz), 3.13–2.92 (3H, m), 0.80 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 171.5, 140.8, 138.9, 138.5, 134.4,
133.7, 129.3, 129.0 (2C), 128.7 (2C), 128.4 (2C), 128.2 (2C), 127.5
(2C), 125.9 (2C), 99.5, 84.7, 61.3, 46.0, 32.2, 13.7.
Anal. Calcd for C25H22Cl2O5•1/2 C6H6: C, 65.63; H, 4.92. Found: C,
65.69; H, 5.00.
All of the 1H NMR spectra were taken with a JNM PMX-60SI, a JNM
EX-90FT and a JNM EX-400FT NMR spectrometer with TMS being
used as the internal standard. Chemical shifts are shown in δ values
(ppm) and coupling constants are shown in J values (Hz). The IR
spectra were measured on a JASCO A-102 IR spectrophotometer and
expressed in ν values (cm–1). MS were taken with a JMS-LX1000, a
Shimadzu QP2000GF and a JMS-BU20 mass spectrometer at an ion-
izing voltage of 70 eV. Mps were determined with a Yanagimoto mi-
cromelting-point apparatus MP-J3. Elemental analyses were per-
formed by the Instrumental Analysis Center, Kumamoto University
and the Microanalytical Center, Kyushu University, Fukuoka.
Ethyl 3,6,6-Tris(4-chlorophenyl)-3-hydroxy-1,2-dioxane-4-carboxy-
late (3bb): mp 167–168°C (benzene).
IR (KBr): ν = 3400, 1711 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.62–7.21 (12H, m), 4.72 (1H, br s),
3.96 (2H, q, J = 7 Hz), 3.14–2.82 (3H, m), 0.97 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 171.3, 140.6, 138.7, 137.1, 135.4,
134.5, 133.8, 129.1 (2C), 128.7 (2C), 128.4 (2C), 128.3 (2C), 127.6
(2C), 127.5 (2C), 99.2, 84.8, 61.5, 45.9, 32.2, 13.8.
Anal. Calcd for C25H21Cl3O5: C, 59.13; H, 4.16. Found: C, 59.26; H,
4.28.
Mn(OAc)3•2 H2O was prepared according to the method in the liter-
ature.15 1,1-Disubstituted ethenes 1a–c, and 1-arylcycloalkenes 1d–h
were prepared by dehydration of the corresponding alcohols which
were synthesized from acetophenones or cycloalkanones and aryl-
magnesium bromides. Ethyl 3-phenyl-3-oxopropanoate (2a) (Wako)
and methyl 3-oxobutanoate (2d) (Wako) were commercially avail-
able, and used as received. Ethyl 3-(4-chlorophenyl)-3-oxopro-
panoate (2b) and ethyl 3-(4-methylphenyl)-3-oxopropanoate (2c)
were prepared according to the literature.16
Ethyl 6,6-Bis(4-chlorophenyl)-3-hydroxy-3-(4-methylphenyl)-1,2-di-
oxane-4-carboxylate (3bc): mp 152–153°C (benzene).
IR (KBr): ν = 3404, 1713 cm–1.
Reactions of 1,1-Diarylethenes 1a–c or 1-Arylcycloalkenes 1d–h
with Active Methylene Compounds 2a–d in the Presence of Man-
ganese(III) Acetate in Acetic Acid; General Procedure:
1H NMR (CDCl3, 60 MHz): δ = 7.63–6.97 (12H, m), 4.74 (1H, br s),
3.93 (2H, q, J = 7 Hz), 3.17–2.89 (3H, m), 2.27 (3H, s), 0.93 (3H, t, J
= 7 Hz).
A mixture of an alkene or cycloalkene (1 mmol) and an active methyl-
ene compound (3 mmol) in HOAc (30 mL) containing manganese ace-
tate was reacted under an air stream for 12 h. The reaction was
quenched by adding water (60 mL) and the mixture was then extracted
with benzene (3 × 30 mL). After removing the benzene, the solidified
products were recrystallized or separated on TLC (Wakogel B10) while
eluting with hexane/Et2O (1:1). The yields are listed in Table 1. The
products were further purified for analytical samples by recrystalliza-
tion from appropriate solvents. Specific details are given below.
13C NMR (CDCl3, 100 MHz): δ = 171.7, 140.9, 139.3, 139.0, 135.6,
134.4, 133.7, 129.0 (2C), 128.9 (2C), 128.7 (2C), 128.4 (2C), 127.5
(2C), 125.9 (2C), 99.5, 84.6, 61.3, 45.8, 32.4, 21.2, 13.8.
Anal. Calcd for C26H24Cl2O5: C, 64.07; H, 4.96. Found: C, 63.98; H,
4.98.
Ethyl 3-Hydroxy-6,6-bis(4-methylphenyl)-3-phenyl-1,2-dioxane-4-
carboxylate (3ca): mp 186–187°C (benzene).
IR (KBr): ν = 3402, 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.66–7.05 (13H, m), 4.60 (1H, br s),
3.97 (2H, q, J = 7 Hz), 3.23–2.94 (3H, m), 2.40 (3H, s), 2.28 (3H, s),
0.95 (3H, t, J = 7 Hz).
Ethyl 3-Hydroxy-3,6,6-triphenyl-1,2-dioxane-4-carboxylate (3aa):
mp 163–164°C (benzene) (lit.9 mp 163°C).
IR (KBr): ν = 3370, 1710 cm–1.

SYNTHESIS
Papers
1460
13C NMR (CDCl3, 100 MHz): δ = 169.5, 140.9, 140.3, 138.6, 137.0,
136.0, 128.8 (2C), 128.7 (2C), 128.3, 127.4 (2C), 126.6 (2C), 126.0
(2C), 125.7 (2C), 99.6, 84.8, 59.5, 46.9, 30.6, 20.6, 20.5, 13.5.
Anal. Calcd for C27H28O5: C, 74.98; H, 6.53. Found: C, 75.01; H,
6.73.
2.70 (1H, d, J = 4.89 Hz), 2.13 (1H, m), 2.02 (1H, m), 1.87 (2H, m),
1.72 (1H, m), 1.57 (2H, m), 1.35 (3H, m), 1.24 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 173.0, 143.8, 128.5 (2C), 127.0,
125.6 (2C), 98.6, 87.0, 52.0, 49.0, 40.9, 40.8, 31.3, 30.6, 26.8, 25.2,
20.9.
Anal. Calcd for C18H24O5: C, 67.48; H, 7.55. Found: C, 67.27; H,
7.67.
Ethyl 3-(4-Chlorophenyl)-3-hydroxy-6,6-bis(4-methylphenyl)-1,2-di-
oxane-4-carboxylate (3cb): mp 166–167°C (EtOH).
IR (KBr): ν = 3402, 1715 cm–1.
Methyl 2-(4-Hydroxy-4-phenyl-2,3-dioxacycloheptyl)-3-oxobu-
tanoate (3hd): mp 93–94°C (EtOH/hexane).
1H NMR (CDCl3, 60 MHz): δ = 7.75–6.97 (12H, m), 4.73 (1H, br s),
4.02 (2H, q, J = 7 Hz), 3.32–2.84 (3H, m), 2.37 (3H, s), 2.24 (3H, s),
0.94 (3H, t, J = 7 Hz).
IR (KBr): ν = 3440, 1738, 1685 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.96–7.27 (5H, m), 4.77 (1H, m),
3.78 (3H, s), 3.33 (1H, d, J = 14 Hz), 3.04–1.84 (7H, m), 1.65 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 199.7, 169.3, 136.8, 133.2, 128.6
(2C), 128.0 (2C), 104.8, 82.7, 67.1, 52.5, 37.7, 33.9, 21.6, 20.2.
FAB MS (positive): m/z = 309 (M+ + 1).
13C NMR (CDCl3, 100 MHz): δ = 171.7, 139.9, 138.1, 137.6 (2C),
137.1, 135.0, 129.3 (2C), 129.0 (2C), 128.2 (2C), 127.7 (2C), 126.8
(2C), 126.1 (2C), 99.1, 85.4, 61.2, 46.2, 32.2, 21.2, 21.0, 13.8.
Anal. Calcd for C27H27ClO5: C, 69.45; H, 5.83. Found: C, 69.45; H,
5.99.
Anal. Calcd for C16H20O6: C, 62.32; H, 6.54. Found: C, 62.45; H,
6.51.
Ethyl 3-Hydroxy-3,6,6-tris(4-methylphenyl)-1,2-dioxane-4-carboxy-
late (3cc): mp 144–145°C (benzene).
2-Acetoxy-1-phenylcyclohexanol (4d): mp 120.5–121.5°C (hexane).
IR (CHCl3): ν = 3600, 3580, 1728, 1241 cm–1.
IR (KBr): ν = 3406, 1718 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.79–6.95 (12H, m), 4.60 (1H, br s),
4.00 (2H, q, J = 7 Hz), 3.30–2.86 (3H, m), 2.36 (3H, s), 2.28 (6H, s),
0.92 (3H, t, J = 7 Hz).
1H NMR (CDCl3, 400 MHz): δ = 7.45–7.20 (5H, m), 5.28 (1H, m),
2.40 (1H, br), 1.95–1.40 (8H, m), 1.78 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 169.8, 146.0, 128.2 (2C), 126.9,
124.7 (2C), 76.3, 75.3, 39.7, 27.2, 24.2, 21.0, 20.8.
Anal. Calcd for C14H18O3: C, 71.77; H, 7.74. Found: C, 71.53; H,
7.95.
13C NMR (CDCl3, 100 MHz): δ = 172.1, 140.1, 139.0, 138.0, 137.8,
136.9, 136.0, 129.2 (2C), 129.0 (2C), 128.7 (2C), 126.8 (2C), 126.1
(2C), 126.0 (2C), 99.3, 85.2, 61.1, 46.1, 32.5, 21.2 (3C), 13.8.
Anal. Calcd for C28H30O5: C, 75.31; H, 6.77. Found: C, 75.52; H,
7.01.
2-Acetoxy-1-(4-chlorophenyl)cyclohexanol (4e): mp 112°C (hexane).
IR (CHCl3): ν = 3600, 3570, 1728, 1240 cm–1.
Methyl 4-Hydroxy-4-methyl-1-phenyl-2,3-dioxabicyclo[4.4.0]de-
cane-5-carboxylate (3dd): mp 139–140°C (EtOH/hexane).
IR (KBr): ν = 3460, 1727 cm–1.
1H NMR (CDCl3, 400 MHz): δ = 7.40–7.27 (4H, m), 5.24 (1H, m),
2.35 (1H, br), 1.96–1.38 (8H, m), 1.82 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 169.7, 144.6, 132.8, 128.4 (2C),
126.3 (2C), 76.1, 75.1, 39.7, 27.2, 24.1, 20.9, 20.8.
Anal. Calcd for C14H17ClO3: C, 62.56; H, 6.38. Found: C, 62.58; H,
6.38.
1H NMR (CDCl3, 60 MHz): δ = 7.63–7.26 (5H, m), 4.24 (1H, br s),
3.88 (3H, s), 3.21 (1H, d, J = 14 Hz), 2.72–1.75 (9H, m), 1.21 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 172.3, 141.4, 128.1 (2C), 128.0
(2C), 127.1, 99.6, 84.2, 52.1, 50.1, 42.6, 38.6, 26.4, 25.9, 25.0, 22.1.
Anal. Calcd for C17H22O5: C, 66.65; H, 7.24. Found: C, 66.67; H,
7.22.
2-Acetoxy-1-(4-methylphenyl)cyclohexanol (4f): mp 92.5°C (hex-
ane).
IR (CHCl3): ν = 3604, 3590, 1730, 1245 cm–1.
1H NMR (CDCl3, 400 MHz): δ = 7.33–7.11 (4H, m), 5.26 (1H, dd, J
= 10.7, 5.4 Hz), 2.32 (3H, s), 2.28 (1H, br), 1.94–1.38 (8H, m), 1.81
(3H, s).
Methyl 1-(4-Chlorophenyl)-4-hydroxy-4-methyl-2,3-dioxabicyclo-
[4.4.0]decane-5-carboxylate (3ed): mp 131–132°C (EtOH/hexane).
IR (KBr): ν = 3460, 1725 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.57–7.34 (4H, m), 4.24 (1H, br s),
3.76 (3H, s), 3.11 (1H, d, J = 14 Hz), 2.72–1.52 (9H, m), 1.22 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 171.9, 140.2, 132.9, 129.6 (2C),
128.1 (2C), 99.7, 84.0, 52.2, 50.1, 42.2, 38.4, 26.3, 25.7, 24.9, 22.0.
Anal. Calcd for C17H21ClO5: C, 59.90; H, 6.21. Found: C, 59.84; H,
6.37.
13C NMR (CDCl3, 100 MHz): δ = 169.8, 143.0, 136.5, 128.9 (2C),
124.6 (2C), 76.2, 75.1, 39.8, 27.2, 24.2, 21.1, 20.9 (2C).
Anal. Calcd for C15H20O3: C, 72.55; H, 8.12. Found: C, 72.77; H,
8.25.
2-Acetoxy-1-phenylcycloheptanol (4g): mp 101–102°C (hexane).
IR (CHCl3): ν = 3600, 3590, 1728, 1243 cm–1.
1H NMR (CDCl3, 400 MHz): δ = 7.45–7.19 (5H, m), 5.26 (1H, dd, J
= 10.7, 2.0 Hz), 2.51 (1H, br), 2.22–1.47 (10H, m), 1.74 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 169.5, 147.7, 128.2 (2C), 126.7,
124.4 (2C), 80.1, 77.5, 40.3, 28.1, 26.9, 23.0, 20.8, 20.4.
Anal. Calcd for C15H20O3: C, 72.55; H, 8.12. Found: C, 72.77; H,
8.19.
Methyl 4-Hydroxy-4-methyl-1-(4-methylphenyl)-2,3-dioxabicyclo-
[4.4.0]decane-5-carboxylate (3fd): mp 186–187°C (EtOH/hexane).
IR (KBr): ν = 3460, 1723 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.63–7.26 (4H, m), 4.24 (1H, br s),
3.88 (3H, s), 3.21 (1H, d, J = 14 Hz), 2.51 (3H, s), 2.72–1.75 (9H, m),
1.21 (3H, s).
13C NMR (CDCl3, 100 MHz): δ = 171.9, 138.9, 134.9, 129.2 (2C),
127.8 (2C), 98.6, 83.1, 52.2, 49.3, 34.1, 27.7, 26.5, 24.6, 23.4, 21.1,
19.8.
Anal. Calcd for C18H24O5: C, 67.48; H, 7.55. Found: C, 67.19; H,
7.66.
Acid-Catalyzed Decomposition of 1,2-Dioxan-3-ols 3aa–cc and
Methyl 4-Hydroxy-2,3-dioxabicyclo[n.4.0]alkane-5-carboxylates
3dd–gd; General Procedure:
A solution of a peroxide (1 mmol) in MeCN or HOAc (15 mL) con-
taining a 60% HClO4 (3 mmol) was heated under reflux for 15 min.
The reaction was quenched with water (60 mL) and the mixture was
extracted with Et2O (3 × 20 mL). The extract was washed with sat.
Na2CO3 (30 mL) and water (30 mL), dried (MgSO4), and evaporated.
The residue was chromatographed on a silica gel plate while eluting
with CHCl3 or benzene. The yields are listed in Table 2. The products
Methyl 10-Hydroxy-10-methyl-7-phenyl-8,9-dioxabicyclo[5.4.0]un-
decane-11-carboxylate (3gd): mp 132–134°C (EtOH).
IR (CHCl3): ν = 3580, 1732 cm–1.
1H NMR (CDCl3, 400 MHz): δ = 7.58 (2H, m), 7.40 (2H, m), 7.29
(1H, m), 3.77 (3H, s), 3.67 (1H, s), 2.86 (1H, dd, J = 9.52, 5.13 Hz),

SYNTHESIS
October 1998
1461
were further purified by recrystallization to obtain analytical samples.
Physical properties of the furans, which were obtained in a pure state,
are described below.
13C NMR (CDCl3, 100 MHz): δ = 163.4, 157.0, 150.8, 139.7, 133.6,
129.0 (2C), 128.8 (2C), 128.4, 128.3 (2C), 126.8, 125.1 (2C), 115.3,
108.3, 60.6, 21.5, 14.3.
MS: m/z (%) = 340 (100, M+), 312 (74), 295 (22), 239 (14), 139 (23),
119 (37), 111 (20), 91 (30).
Ethyl 2,5-Diphenylfuran-3-carboxylate (5aa): mp 41–42°C (hexane)
(lit.17 mp 79–80°C).
Anal. Calcd for C20H1735ClO3: M, 340.0866. Found: m/z 340.0877.
IR (CHCl3): ν = 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 8.09–7.30 (10H, m), 7.08 (1H, s),
4.32 (2H, q, J = 7 Hz), 1.35 (3H, t, J = 7 Hz).
Ethyl 5-(4-Methylphenyl)-2-phenylfuran-3-carboxylate (5ca): color-
less liquid.
13C NMR (CDCl3, 100 MHz): δ = 163.5, 156.4, 152.3, 129.7, 129.3,
128.8 (2C), 128.5, 128.4 (2C), 128.1 (2C), 128.0, 124.0 (2C), 115.7,
107.9, 60.6, 14.3.
IR (CHCl3): ν = 1715 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 8.07–7.32 (9H, m), 7.15 (1H, s), 4.29
(2H, q, J = 7 Hz), 2.31 (3H, s), 1.32 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 163.4, 155.9, 152.4, 137.8, 129.7,
126.9, 129.3 (2C), 129.0, 128.2 (2C), 127.9 (2C), 123.8 (2C), 115.6,
107.0, 60.4, 21.1, 14.1.
MS: m/z (%) = 292 (100, M+), 264 (77), 247 (32), 105 (53), 77 (63).
Ethyl 2-(4-Chlorophenyl)-5-phenylfuran-3-carboxylate (5ab): mp
75–76°C (hexane).
MS: m/z (%) = 306 (100, M+), 278 (80), 261 (21), 205 (22), 119 (22),
105 (40), 91 (23), 77 (35).
IR (CHCl3): ν = 1717 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 8.08–7.30 (9H, m), 7.12 (1H, s), 4.33
(2H, q, J = 7 Hz), 1.36 (3H, t, J = 7 Hz).
Anal. Calcd for C20H18O3: M, 306.1256. Found: m/z 306.1226.
13C NMR (CDCl3, 100 MHz): δ = 163.4, 155.1, 152.5, 135.2, 129.8
(2C), 129.6, 128.8 (2C), 128.4 (2C), 128.1, 128.2, 124.0 (2C), 116.1,
108.0, 60.8, 14.3.
Ethyl 2-(4-Chlorophenyl)-5-(4-methylphenyl)furan-3-carboxylate
(5cb): mp 68–69°C (hexane).
IR (CHCl3): ν = 1710 cm–1.
MS: m/z (%) = 326 (100, M+), 298 (79), 281 (26), 225 (22), 189 (22),
139 (36), 111 (23), 105 (40), 77 (54).
1H NMR (CDCl3, 60 MHz): δ = 8.14–7.26 (8H, m), 7.02 (1H, s), 4.34
(2H, q, J = 7 Hz), 2.37 (3H, s), 1.35 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 163.5, 154.8, 152.8, 139.9, 135.1,
129.6 (2C), 129.2, 129.1 (2C), 128.8, 128.3 (2C), 124.0 (2C), 116.0,
107.3, 60.7, 21.3, 14.2.
Anal. Calcd for C19H1535ClO3: M, 326.0710. Found: m/z 326.0747.
Ethyl 2-(4-Methylphenyl)-5-phenylfuran-3-carboxylate (5ac): color-
less liquid.
MS: m/z (%) = 340 (81, M+), 312 (100), 295 (13), 239 (28), 119 (27),
111 (17), 91 (28).
IR (CHCl3): ν = 1715 cm–1.
1H NMR (CDCl3, 60 MHz,): δ = 8.06–7.27 (9H, m), 7.09 (1H, s),
4.37 (2H, q, J = 7 Hz), 2.38 (3H, s), 1.34 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 163.6, 156.8, 151.9, 139.5, 129.8,
129.5, 129.3, 128.8, 128.76 (2C), 128.2 (2C), 128.0, 123.9 (2C),
115.2, 107.8, 60.6, 21.5, 14.3.
Anal. Calcd for C20H1735ClO3: M, 340.0866. Found: m/z 340.0853.
Ethyl 2,5-Bis(4-methylphenyl)furan-3-carboxylate (5cc): mp 72–
73°C (hexane).
IR (CHCl3): ν = 1710 cm–1.
MS: m/z (%) = 306 (100, M+), 278 (78), 261 (26), 205 (20), 119 (21),
105 (21), 91 (21), 77 (35).
1H NMR (CDCl3, 60 MHz): δ = 7.97–7.18 (8H, m), 7.00 (1H, s), 4.31
(2H, q, J = 7 Hz), 2.39 (3H, s), 2.35 (3H, s), 1.35 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 163.7, 156.4, 152.2, 139.4, 137.8,
129.4 (2C), 128.8 (2C), 128.2 (2C), 127.1, 127.0, 123.9 (2C), 115.1,
107.1, 60.5, 21.4, 21.3, 14.2.
Anal. Calcd for C20H18O3: M, 306.1256. Found: m/z 306.1226.
Ethyl 5-(4-Chlorophenyl)-2-phenylfuran-3-carboxylate (5ba): mp
54–56°C (hexane).
MS: m/z (%) = 320 (100, M+), 292 (76), 275 (15), 219 (17), 119 (45),
91 (46).
IR (CHCl3): ν = 1715 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 8.23–7.27 (9H, m), 7.13 (1H, s), 4.30
(2H, q, J = 7 Hz), 1.33 (3H, t, J = 7 Hz).
Anal. Calcd for C21H20O3: M, 320.1412. Found: m/z 320.1427.
13C NMR (CDCl3, 100 MHz): δ = 163.4, 156.7, 151.2, 133.8, 129.5,
129.2, 129.0 (2C), 128.4 (2C), 128.2 (2C), 128.1, 125.2 (2C), 115.8,
108.4, 60.7, 14.2.
Methyl 4-(4-Hydroxybutyl)-2-methyl-5-phenylfuran-3-carboxylate
(5dd): yellow liquid.
IR (CHCl3): ν = 3528, 1702 cm–1.
MS: m/z (%) = 326 (100, M+), 298 (86), 281 (29), 225 (23), 189 (25),
139 (28), 111 (26), 105 (54), 77 (55).
1H NMR (CDCl3, 60 MHz): δ = 7.92–7.13 (5H, m), 3.88 (3H, s),
4.16–3.43 (2H, m), 3.14–2.30 (2H, m), 2.23–1.19 (4H, m), 2.1 (1H,
br s), 1.20 (3H, s).
Anal. Calcd for C19H1535ClO3: M, 326.0710. Found: m/z 326.0731.
13C NMR (CDCl3, 22.5 MHz): δ = 165.1, 158.9, 147.9, 130.9, 128.6
(2C), 127.5, 126.1 (2C), 122.0, 114.1, 51.2, 62.0, 32.3, 26.3, 23.8,
14.7.
Ethyl 2,5-Bis(4-chlorophenyl)furan-3-carboxylate (5bb): mp 106–
108°C (hexane).
IR (CHCl3): ν = 1710 cm–1.
MS: m/z (%) = 288 (37, M+), 229 (38), 211 (23), 197 (21), 169 (19),
155 (14), 141 (15), 115 (11), 105 (51), 77 (44), 51 (13), 43 (100).
Anal. Calcd for C17H20O4: M, 288.1361. Found: m/z 288.1394.
1H NMR (CDCl3, 60 MHz): δ = 8.14–7.30 (8H), 7.07 (1H, s), 4.33
(2H, q, J = 7 Hz), 1.34 (3H, t, J = 7 Hz).
13C NMR (CDCl3, 100 MHz): δ = 163.3, 155.4, 151.4, 141.1, 135.4,
134.0, 129.6 (2C), 129.1 (2C), 128.5 (2C), 128.0, 125.2 (2C), 116.2,
108.5, 60.9, 13.9.
Methyl 5-(4-Chlorophenyl)-4-(4-hydroxybutyl)-2-methylfuran-3-
carboxylate (5ed): mp 77–78°C (hexane).
MS: m/z (%) = 360 (100, M+), 332 (72), 315 (22), 259 (16), 189 (18),
139 (78), 111 (60), 75 (27).
IR (CHCl3): ν = 3620, 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.50–7.27 (4H, m), 3.86 (3H, s),
3.72–3.52 (2H, m), 2.94–2.78 (2H, m), 2.59 (3H, s), 2.0 (1H, br s),
1.76–1.23 (4H, m).
Anal. Calcd for C19H1435Cl2O3: M, 360.0320. Found: m/z 360.0350.
Ethyl 5-(4-Chlorophenyl)-2-(4-methylphenyl)furan-3-carboxylate
(5bc): mp 77–78°C (hexane).
13C NMR (CDCl3, 100 MHz): δ = 164.9, 159.1, 146.6, 133.2, 129.2,
128.9 (2C), 127.1 (2C), 122.5, 114.4, 61.9, 51.3, 32.2, 26.1, 23.7, 14.7.
MS: m/z (%) = 322 (37, M+), 288 (74), 263 (35), 245 (17), 213 (16),
139 (31), 111 (19), 43 (100).
IR (CHCl3): ν = 1715 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.95–7.24 (8H, m), 7.04 (1H, s), 4.31
(2H, q, J = 7 Hz), 2.39 (3H, s), 1.35 (3H, t, J = 7 Hz).
Anal. Calcd for C17H1935ClO4: M, 322.0972. Found: m/z 322.0955.

SYNTHESIS
Anal. Calcd for C19H22O5: M, 330.1467. Found: m/z 330.1492.
This compound was also obtained when 5dd (1 mmol) was treated
with HOAc (15 mL) containing 60% perchloric acid (3 mmol) and the
reaction mixture was separated in a manner similar to that previously
described.
Papers
1462
Methyl 4-(4-Hydroxybutyl)-2-methyl-5-(4-methylphenyl)furan-3-
carboxylate (5fd): colorless liquid.
IR (CHCl3): ν = 3470, 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.45–7.19 (4H, m), 3.70 (3H, s),
3.82–3.67 (3H, m), 3.50–2.62 (2H, m), 2.57 (3H, s), 2.35 (3H, s),
1.89–1.62 (4H, m).
13C NMR (CDCl3, 100 MHz): δ = 165.1, 158.6, 147.9, 137.2, 129.3
(2C), 128.0, 125.9 (2C), 121.2, 114.2, 62.0, 51.1, 32.3, 26.3, 23.8,
21.2, 14.7.
(1) Arcadi, A.; Cacci, S.; Larock, R. C.; Marinelli, F. Tetrahedron
Lett. 1993, 34, 2816.
(2) Da Silva, G. V.; Pelisson, J. M. M.; Constantino, M. G. Tetra-
hedron Lett. 1994, 35, 7327.
MS: m/z (%) = 302 (100, M+), 243 (68), 211 (34), 183 (26), 169 (22),
119 (27), 91 (23), 43 (71).
Anal. Calcd for C18H22O4: M, 302.1518. Found: m/z 302.1521.
(3) Dean, F. M. Naturally Occurring Oxygen Ring Compounds;
Butterworth: London, 1963; pp 1–28.
Methyl 4-(5-Hydroxypentyl)-2-methyl-5-phenylfuran-3-carboxylate
(5gd): colorless liquid.
(4) Antonioletti, R.; Cecchini, C.; Ciani, B.; Magnanti, S. Tetrahe-
dron Lett. 1995, 36, 9019.
(5) Tategami, S.; Yamada, T.; Nishino, H.; Korp, J. D.; Kurosawa,
K. Tetrahedron Lett. 1990, 31, 6371.
(6) Nishino, H.; Tategami, S.; Yamada, T.; Korp, J. D.; Kurosawa,
K. Bull. Chem. Soc. Jpn. 1991, 64, 1800.
(7) Qian, C-Y.; Nishino, H.; Kurosawa, K. Bull. Chem. Soc. Jpn.
1991, 64, 3557.
(8) Qian, C-Y.; Yamada, T.; Nishino, H.; Kurosawa, K. Bull.
Chem. Soc. Jpn. 1992, 65, 1371.
(9) Yamada, T.; Iwahara, Y.; Nishino, H.; Kurosawa, K. J. Chem.
Soc., Perkin Trans. 1 1993, 609.
IR (CHCl3): ν = 3640, 1710 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.57–7.26 (5H, m), 3.85 (3H, s),
3.63–3.56 (2H, m), 3.04–2.79 (2H, m), 2.16–1.47 (6H, m), 2.60 (3H,
s).
13C NMR (CDCl3, 100 MHz): δ = 165.0, 158.8, 147.6, 130.9, 128.6
(2C), 127.4, 126.0 (2C), 122.0, 114.4, 62.9, 51.1, 32.4, 30.2, 25.9,
24.5, 14.6.
MS: m/z (%) = 302 (74, M+), 229 (65), 197 (27), 169 (21), 141 (22),
105 (46), 77 (38), 43 (100).
Anal. Calcd for C18H22O4: M, 302.1518. Found: m/z 302.1489.
(10) Qian, C-Y.; Nishino, H.; Kurosawa, K.; Korp, J. D. J. Org.
Chem. 1993, 58, 4448.
(11) Qian, C-Y.; Hirose, J.; Nishino, H.; Kurosawa, K. J. Heterocycl.
Chem. 1994, 31, 1219.
(12) Ouyang, J.; Nishino, H.; Kurosawa, K. J. Heterocycl. Chem.
1995, 32, 1783.
(13) Nguyen, V.-H.; Nishino, H.; Kurosawa, K. Synthesis 1997, 899.
(14) Anderson, G. H.; Smith, J. G. Can. J. Chem. 1968, 46, 1561.
(15) Andrulis, P. J. Jr.; Dewar, M. J. S.; Dietz, R.; Hunt, R. J. Am.
Chem. Soc. 1966, 88, 5473.
Methyl 4-(4-Acetoxybutyl)-2-methyl-5-phenylfuran-3-carboxylate
(6dd): yellow liquid.
IR (CHCl3): ν = 1708 cm–1.
1H NMR (CDCl3, 60 MHz): δ = 7.83–7.24 (5H, m), 4.24–3.94 (2H,
m), 3.86 (3H, m), 3.09–2.57 (2H, m), 2.60 (3H, s), 2.20 (3H, s), 2.23–
1.19 (4H, m).
13C NMR (CDCl3, 22.5 MHz): δ = 171.1, 165.1, 158.9, 147.8, 130.9,
128.6 (2C), 127.5, 126.1 (2C), 121.6, 114.4, 51.1, 64.3, 28.6, 26.8,
24.2, 21.0, 14.6.
MS: m/z (%) = 330 (40, M+), 256 (23), 242 (11), 229 (31), 215 (10),
211 (22), 197 (16), 169 (13), 155 (11), 141 (12), 105 (28), 77 (22), 43
(100).
(16) Singer, S.; Zuman, P. J. Org. Chem. 1974, 39, 836.
(17) Clawson, P.; Lunn, P. M.; Whiting, D. A. J. Chem. Soc., Perkin
Trans. 1 1990, 153.