Five-Membered 2,3-Dioxo Heterocycles: XLV. Thermolysis of 5-Aryl-4-phenyl-2,3-dihydrofuran-2,3-diones in the Absence of Other Partners and in the Presence of Carbonyl Compounds

Article abstract of DOI:10.1023/A:1023454915387

Aroyl(phenyl)ketenes generated by thermolysis of 5-aryl-4-phenyl-2,3- dihydrofuran-2,3-diones undergo [4+2]-cyclodimerization to 3-aroyl-6-aryl-3,5- diphenyl-3,4-dihydro-2H-pyran-2,4-diones. Heating of the latter leads to rearrangement with formation of 4-aroyloxy-6-aryl-3,5-diphenyl-2H-pyran-2-ones. Thermolysis of 5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones in the presence of carbonyl compounds yields 6-aryl-5-phenyl-4H-1,3-dioxin-4-ones.

Full text of DOI:10.1023/A:1023454915387

Russian Journal of Organic Chemistry, Vol. 39, No. 1, 2003, pp. 103 107. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 1, 2003,
pp. 113 117.
Original Russian Text Copyright
2003 by Vostrov, Leont’eva, Tarasova, Maslivets.
Five-Membered 2,3-Dioxo Heterocycles: XLV.* Thermolysis
of 5-Aryl-4-phenyl-2,3-dihydrofuran-2,3-diones in the Absence
of Other Partners and in the Presence of Carbonyl Compounds
E. S. Vostrov, E. V. Leont’eva, O. P. Tarasova, and A. N. Maslivets
Perm State University, ul. Bukireva 15, Perm, 614099 Russia
e-mail: koh@psu.ru
Received July 19, 2002
Abstract Aroyl(phenyl)ketenes generated by thermolysis of 5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones
undergo [4+2]-cyclodimerization to 3-aroyl-6-aryl-3,5-diphenyl-3,4-dihydro-2H-pyran-2,4-diones. Heating
of the latter leads to rearrangement with formation of 4-aroyloxy-6-aryl-3,5-diphenyl-2H-pyran-2-ones.
Thermolysis of 5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones in the presence of carbonyl compounds yields
6-aryl-5-phenyl-4H-1,3-dioxin-4-ones.
5-Aryl-2,3-dihydrofuran-2,3-diones containing no
substituent in position 4 are thermally unstable. They
undergo decomposition on heating to a temperature
near the melting point (130 140 C). The temperature
of their decomposition in solution is lower by 50
70 C. The process is accompanied by elimination of
carbon(II) oxide to give reactive aroylketenes [2 5].
Stabilization pathways of the latter are determined by
the nature of substituent in position 4 of their furan-
dione precursor. The most probable pathway is inter-
molecular [4+2]-cycloaddition ([4+2]-cyclodimeriza-
tion), where one aroylketene molecule acts as diene
(aroylketene fragment O C C C), and the other, as
dienophile (ketene C C bond).
uct having two halogen atoms was isolated only from
4-chloro-5-p-tolyl-2,3-dihydrofuran-2,3-dione [4].
With the goal of estimating the effect of phenyl
group in position 4 of 5-aryl-2,3-dihydrofuran-2,3-di-
ones on their thermal decomposition, we synthesized
5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones Ia Ic
and studied their thermolysis both in the absence of
other reaction partners and in the presence of carbonyl
compounds. Substituted furandiones Ia Ic were pre-
pared by reaction of the corresponding aryl benzyl
ketones with iodotrimethylsilane [5] and subsequent
treatment of the resulting trimethylsilyl enol ethers
with oxalyl chloride in boiling chloroform (reaction
time 2 3 h; Scheme 1). Furandiones Ia c (Table 1)
are yellow orange crystalline substances, readily
soluble in polar aprotic organic solvents and poorly
soluble in alkanes. They react with water and alcohols
and lose their color on storage in air due to reaction
with atmospheric moisture (addition of water leads to
opening of the furan ring).
5-Aryl-4-methyl-2,3-dihydrofuran-2,3-diones under
thermolysis conditions give rise to aroyl(methyl)-
ketenes which are stabilized according to the above
[4+2]-cyclodimerization pathway to afford 3-aroyl-
6-aryl-3,5-dimethyl-3,4-dihydro-2H-pyran-2,4-diones
[2]. Aroylketenes generated from 4-unsubstituted
5-aryl-2,3-dihydrofuran-2,3-diones are converted into
3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones as a result
of 1,3-H shift in the primary [4+2]-cycloadducts [3].
Thermolysis of 5-aryl-4-halo-2,3-dihydrofuran-2,3-di-
ones gives aroyl(halo)ketenes which undergo cyclodi-
merization to 3-aroyl-6-aryl-3,5-dihalo-3,4-dihydro-
2H-pyran-2,4-diones. Hydrolysis of the latter on
attempted recrystallization yields 3-aroyl-6-aryl-
5-halo-4-hydroxy-2H-pyran-2-ones. The dimeric prod-
____________
The IR spectra of Ia Ic (Table 2) contain bands
due to stretching vibrations of the lactone carbonyl
1
group (C2 O; 1810 1825 cm ) and ketone carbonyl
1
group (C3 O; 1705 1730 cm ), in keeping with
published data for analogous compounds having no
substituent in position 4 and 4-methyl and 4-halogen
derivatives [6 8]. In the 13C NMR spectrum of com-
pound Ic, signals from the furan ring carbon atoms
appear at
154.16 (C2), 178.96 (C3), 118.31 (C4),
and 176.31Cppm (C5). The downfield position of the
C5 signal and the upfield position of the C2 signal
*
For communication XLIV, see [1].
1070-4280/03/3901-0103$25.00 2003 MAIK Nauka/Interperiodica

104
VOSTROV et al.
Scheme 1.
Ia IVa, Va, Vb, VIa, VIb, Ar = Ph; Ib, IIb, IVb, Vc, Ar = 4-MeC6H4; Ic, IIc, IIIb, IVc, Vd Vg, Ar = 2,5-Me2C6H3;
Va, R1 = Ph; Vb d, R1 = H; Va, R2 = CH2Ph; Vb, d, R2 = 4-BrC6H4; Vc, R2 = 4-MeOC6H4; Ve, R1R2 = (CH2)4; Vf, R1R2 =
(CH2)6; Vg, R1R2C O = 2-adamantanone; VIa, R3 = 4-MeC6H4; VIb, R3 = 4-MeOC6H4.
are well consistent with the known data for 4-unsub-
stituted analogs [9].
2 3 h, we isolated 4-aroyloxy-6-aryl-3,5-diphenyl-2H-
pyran-2-ones IVa IVc (Table 1). Compounds IVa
IVc are colorless or pale yellow crystalline substances
which are readily soluble in common organic solvents
(except for alkanes) and poorly soluble in water. Their
IR spectra (Table 2) are characterized by the presence
of lactone carbonyl (C2 O) absorption at 1735
Heating of furandiones Ia Ic in p-xylene at 135
140 C for 30 40 min resulted in their decarbonylation
to give aroyl(phenyl)ketenes IIa IIc which underwent
[4+2]-cyclodimerization with formation of 3-aroyl-
6-aryl-3,5-diphenyl-3,4-dihydro-2H-pyran-2,4-diones
IIIa and IIIb (Scheme 1). The products showed in
the IR spectra (Table 2) absorption bands belonging
to stretching vibrations of the lactone carbonyl group
1
1755 cm and ester carbonyl (4-OCOAr) absorption
1
at 1720 1735 cm . In the 13C NMR spectrum of IVb
we observed signals from aromatic carbon atoms in
1
(C2 O, 1720 1745 cm ) and ketone carbonyl groups
the region
123.49 145.94 ppm, methyl groups at
20.64 anCd 20.94 ppm, and carbon atoms of the
1
1
(C4 O, 1690 1695 cm ; ArC O, 1652 1660 cm ).
The 13C NMR spectrum of IIIa contained signals
from aromatic carbon atoms ( 126.10 135.00 ppm),
and those belonging to the pCyran ring and benzoyl
pCyran ring and ester carbonyl group, C, ppm: 161.92
(C2), 116.80 (C3), 158.59 (C4), 115.69 (C5), 168.54
(C6), 161.20 (4-OCO). The mass spectrum of IVb
contained the following ion peaks, m/z (Irel, %): 472
carbonyl, C, ppm: 154.51 (C2), 66.11 (C3), 194.35
(C4), 116.66 (C5), 170.03 (C6), 178.88 (PhCO). These
(6) [M]+ , 119 (100) [4-MeC6H4CO]+, 91 (24)
[MeC6H4]+.
data are consistent with the assumed structure.
Presumably, compounds IVa IVc are formed as
a result of [1,3]-acylotropic shift of the aroyl group
in the primary [4+2]-cycloadducts like III. A similar
When thermolysis of furandiones Ia Ic was per-
formed under more severe conditions, by heating in
1,2,4-trimethylbenzene or decane at 160 165 C for
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 1 2003

FIVE-MEMBERED 2,3-DIOXO HETEROCYCLES: XLV.
Table 1. Yields, melting points, and elemental analyses of compounds I and III VI
Found, %
105
Calculated, %
Comp.
no.
Yield,
%
mp, C (solvent)
Formula
C
H
C
H
Ib
Ic
48
47
65
55
95
87
85
94
83
79
78
75
87
90
88/82
93
154 155 (decomp., CHCl3 hexane)
131 132 (decomp., CHCl3 hexane)
160 161 (cyclohexane)
160 162 (cyclohexane)
195 196 (1,4-dioxane)
241 243 (1,4-dioxane)
214 216 (i-PrOH)
157 158 (CCl4)
205 206 (1,2-dichloroethane)
151 153 (CCl4)
137 139 (CCl4 hexane)
132 133 (hexane)
141 142 (cyclohexane)
165 166 (cyclohexane)
186 187 (i-PrOH)
77.15
77.70
81.02
82.25
81.03
81.35
82.23
83.20
64.89
77.38
66.25
79.04
79.53
80.98
80.22
76.52
4.60
5.03
4.55
5.68
4.54
5.10
5.69
5.31
3.70
5.44
4.39
6.60
7.24
7.04
5.80
5.50
C17H12O3
C18H14O3
C30H20O4
C34H28O4
C30H20O4
C32H24O4
C34H28O4
C29H22O3
C22H15BrO3
C24H20O4
C24H19BrO3
C22H22O3
C24H26O3
C27H28O3
C22H19NO2
C22H19NO3
77.26
77.68
81.07
82.24
81.07
81.34
82.24
83.23
64.88
77.40
66.22
79.02
79.53
80.97
80.22
76.50
4.58
5.07
4.54
5.68
4.54
5.12
5.68
5.30
3.71
5.41
4.40
6.63
7.23
7.05
5.81
5.54
IIIa
IIIb
IVa
IVb
IVc
Va
Vba
Vc
Vdb
Ve
Vf
Vg
VIac
VIbd
189 190 (i-PrOH)
a
b
c
Found Br, %: 19.39. Calculated Br, %: 19.62.
Found Br, %: 18.07. Calculated Br, %: 18.35.
Found N, %: 4.20. Calculated N, %: 4.25.
Found N, %: 3.98. Calculated N, %: 4.06.
d
shift was observed previously in the thermolysis of
3,3,5-tribenzoyl-5-phenyl-3,4-dihydro-2H-pyran-2,4-
dione [10] which is structurally related to III.
IR patterns are in agreement with published data for
analogs of V having no substituent on C5 [12]. The
1H NMR spectra of Va Vg (Table 2) contain signals
from protons of the aromatic substituents and groups
attached thereto, a doublet of doublets (AB system)
from diastereotopic protons of the benzyl CH2 group
( 3.54 and 3.61 ppm, compound Va), a singlet from
2-H ( 6.56 7.05 ppm, Vb Vd), methylene proton
signals ( 1.62 2.41 ppm, Ve and Vf), and signals
from protons of the adamantane moiety in Vg ( 1.73
2.67 ppm). The following signals were present in the
13C NMR spectrum of Vf, C, ppm: 126.88 134.43
(Carom), 18.50 36.76 (CH2, CH3), 110.16 (C2), 160.32
(C4), 108.72 (C5), 163.52 (C6). The mass spectrum of
Vb contains low-intense molecular ion peak, m/z 407
(Irel 1%) and fragment ion peaks with m/z (Irel, %)
222 (60) [Ph(PhCO)C C O]+, 105 (100) [PhCO]+,
and 77 (34) [Ph]+.
We also examined thermal decomposition of furan-
diones Ia Ic in the presence of carbonyl compounds.
A mixture of Ia Ic and benzyl phenyl ketone, sub-
stituted benzaldehyde, cycloalkanone, or 2-adamanta-
none was heated in an inert aprotic solvent (dowtherm
A [11], 1,2,4-trimethylbenzene, or m-xylene) at 140
170 C for 20 30 min. As in the preceding cases,
aroyl(phenyl)ketenes IIa IIc were generated as
a result of thermal decarbonylation of furandiones
Ia Ic. The subsequent [4+2]-cycloaddition of aroyl-
ketene II (through the C C C O fragment) at the
C O group of aldehyde or ketone afforded 6-aryl-
5-phenyl-4H-1,3-dioxin-4-ones Va Vg (Table 1).
Compounds Va Vg are colorless crystalline sub-
stances, readily soluble in common organic solvents,
poorly soluble in alkanes, and insoluble in water.
Heating of dioxinone Va in dowtherm A at 140
142 C for 20 25 min in the presence of arylamines
induced its retro-Diels Alder decomposition with
elimination of benzyl phenyl ketone and generation of
benzoyl(phenyl)ketene. The latter reacted with aryl-
The IR spectra of Va Vg (Table 2) contain a strong
1
lactone carbonyl band at 1720 1740 cm and a weak
1
band at 1610 1615 cm , the latter belonging to
stretching vibrations of the C5 C6 band. The observed
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 1 2003

106
VOSTROV et al.
Table 2. IR and 1H NMR spectra of compounds I and III VI
Comp.
no.
1
IR spectrum, , cm
1H NMR spectrum, , ppm
Ib
Ic
1825 (C2 O), 1715 (C3 O)
1825 (C2 O), 1730 (C3 O)
2.11 s (3H, Me), 2.30 s (3H, Me), 7.16 7.30 m (8H, Harom)
IIIa
1745 (C2 O), 1690 (C4 O), 1652 (PhCO), 6.98 7.72 m (Harom
1610 w (C5 C6)
)
IIIb
IVa
IVb
IVc
1720 (C2 O), 1695 (C4 O), 1660 (ArCO), 2.52 s (3H, Me), 2.54 s (3H, Me), 2.56 s (3H, Me), 2.58 s
1613 w (C5 C6)
(3H, Me), 6.90 7.70 m (16H, Harom)
1755 (C2 O), 1735 (PhOCO), 1608 w 7.04 d (2H), 7.25 7.81 m (18H, Harom
(C5 C6)
)
1735 (C2 O), 1730 (4-OCO), 1610 w 2.31 s (3H, Me), 2.34 s (3H, Me), 7.11 7.48 m (18H, Harom
)
)
(C5 C6)
1747 (C2 O), 1720 (4-OCO), 1610 w 2.52 s (6H, Me), 2.54 s (6H, Me), 6.96 7.56 m (16H, Harom
(C5 C6)
Va
Vb
Vc
1740 (C4 O), 1610 w (C5 C6)
1728 (C4 O), 1612 w (C5 C6)
1728 (C4 O), 1615 w (C5 C6)
3.54 d and 3.61 d (AB), 6.75 7.50 m (20H, Harom
7.05 s (1H, 2-H), 7.20 7.70 m (14H, Harom
2.1 s (3H, Me), 3.5 s (3H, OMe), 7.0 s (1H, 2-H), 7.2 7.9 m
(13H, Harom
2.17 s (3H, Me), 2.22 s (3H, Me), 6.94 s (1H, 2-H), 7.00
7.65 m (12H, Harom
2.07 s (3H, Me), 2.19 s (3H, Me), 1.80 1.95 m and 2.25
2.53 m (8H, CH2), 6.98 7.25 m (8H, Harom
2.07 s (3H, Me), 2.15 s (3H, Me), 1.62 s and 2.35 q (12H,
CH2), 6.98 7.16 m (8H, Harom
1.98 s (3H, Me); 2.23 s (3H, Me); 1.78 t, 1.92 t, 2.05 s, and
2.67 s (14H, adamantane); 6.96 7.16 m (8H, Harom
1689 (C3 O), 1670 (C1 O), 3300 (NH), 2.28 s (3H, Me), 5.90 s (1H, CH), 7.00 8.05 m (14H, Harom),
1560 ( NH) 10.10 s (1H, NH)
1690 (C3 O), 1670 (C1 O), 3320 (NH), 3.70 s (3H, OMe), 5.94 s (1H, CH), 6.85 8.03 m (14H, Harom),
1570 ( NH) 10.29 s (1H, NH)
)
)
)
Vd
Ve
1740 (C4 O), 1613 w (C5 C6)
1730 (C4 O), 1597 w (C5 C6)
1720 (C4 O), 1615 w (C5 C6)
1735 (C4 O), 1610 w (C5 C6)
)
)
Vf
)
Vg
VIa
VIb
)
amine, yielding N-aryl- -phenylbenzoylacetamides
VIa and VIb. Amides VIa and VIb (Table 1) are
colorless crystalline substances, readily soluble in
common organic solvents, poorly soluble in alkanes,
and insoluble in water. The IR spectra of VIa and
EXPERIMENTAL
The IR spectra were recorded on a UR-20 spec-
trometer from samples dispersed in mineral oil.
The H NMR spectra were measured on RYa-2310
1
1
VIb (Table 2) contain a band at 3300 3340 cm due
(60 MHz) and Bruker DRX-400 (400 MHz) instru-
ments using DMSO-d6 as solvent and TMS as internal
reference. The 13C NMR spectra were obtained on
a Bruker DRX-400 spectrometer at 100 MHz using
DMSO-d6 as solvent.** The mass spectra (70 eV)
were run on an MKh-1320 mass spectrometer. The
purity of the products was checked by TLC on Silufol
plates using ethyl acetate, ethyl acetate benzene (1:5),
____________
to NH stretching vibrations, amide I band at 1670
1
1
1675 cm , ketone carbonyl band at 1689 1690 cm ,
and amide II band at 1560 1570 cm . In the 1H NMR
1
spectra, the 2-H signal appears as a singlet at 5.90
5.94 ppm, and the NH proton gives a singlet at
10.10 10.29 ppm. Also, signals from aromatic
protons and protons of methyl (VIa) or methoxy
group (VIb) were present.
The structure of amide VIa was proved by in-
dependent synthesis, by thermolysis of N-p-tolyl-2,4-
dioxo-3,4-diphenylbutanamide (VII) [13].
**
The NMR studies were performed at the Ural YaMR TsKP
(Russian Foundation for Basic Research, project no. 00-03-
40139).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 1 2003

FIVE-MEMBERED 2,3-DIOXO HETEROCYCLES: XLV.
107
and benzene as eluent; the chromatograms were
developed with iodine vapor.
This study was financially supported by the Rus-
sian Foundation for Basic Research (project nos. 01-
03-32641, 02-03-96411, 02-03-06605).
5-Aryl-4-phenyl-2,3-dihydrofuran-2,3-diones
Ia Ic [12]. A solution of 0.1 mol of 1-aryl-1-tri-
methylsiloxy-2-phenylethene and 0.1 mol of oxalyl
chloride in 60 ml of dry chloroform was heated for
2 4 h under reflux. The solvent was distilled off under
reduced pressure (water-jet pump) on heating on
a water bath, 100 ml of dry hexane was added, the
mixture was heated to the boiling point and cooled,
and the precipitate was filtered off.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 1 2003