Chemistry of 1,5-diketones: II. Specificity of transformations of polycyclic 1,5-diketones in acid media

Article abstract of DOI:10.1134/S1070428008090030

2-(1,3-Diaryl-3-oxopropyl)cyclohexan-1-ones underwent carbo-and heterocyclization in a mixture of acetic acid with acetic anhydride in the presence of perchloric acid. The transformation of 2-(1,3-diaryl-3-oxopropyl) cyclohexan-1-ones into 2,4-diaryl-5,6,7,8-tetrahydrochromenylium salts was shown to involve intermediate 2,4-diarylbicyclo[3.3.1]non-2-en-9-ones. The structure of 2,4-diaryl-substituted bicyclo[3.3.1]non-2-en-9-ones and products of their reactions with halogens and hydroxylamine hydrochloride was confirmed by ¹H and ¹³C NMR spectroscopy.

Full text of DOI:10.1134/S1070428008090030

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 9, pp. 1267–1270. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © N.V. Pchelintseva, Ya.G. Kolevatova, L.I. Markova, O.V. Fedotova, P.V. Reshetov, 2008, published in Zhurnal Organicheskoi
Khimii, 2008, Vol. 44, No. 9, pp. 1283–1286.
Chemistry of 1,5-Diketones: II.* Specificity of Transformations
of Polycyclic 1,5-Diketones in Acid Media
N. V. Pchelintseva, Ya. G. Kolevatova, L. I. Markova, O. V. Fedotova, and P. V. Reshetov
Chernyshevskii Saratov State University, ul. Astrakhanskaya 83, Saratov, 410012 Russia
e-mail: KolevatovaJG@mail.ru
Received October 6, 2007
Abstract—2-(1,3-Diaryl-3-oxopropyl)cyclohexan-1-ones underwent carbo- and heterocyclization in a mixture
of acetic acid with acetic anhydride in the presence of perchloric acid. The transformation of 2-(1,3-diaryl-3-
oxopropyl)cyclohexan-1-ones into 2,4-diaryl-5,6,7,8-tetrahydrochromenylium salts was shown to involve
intermediate 2,4-diarylbicyclo[3.3.1]non-2-en-9-ones. The structure of 2,4-diaryl-substituted bicyclo[3.3.1]non-
2-en-9-ones and products of their reactions with halogens and hydroxylamine hydrochloride was confirmed by
1H and 13C NMR spectroscopy.
DOI: 10.1134/S1070428008090030
We previously reported [1] on the halogenation of
acyclic 1,5-diketones and their fused analogs. In con-
tinuation of our studies on the properties of 1,5-di-
carbonyl compounds we examined their behavior in
acid media. It is known that 2-(1,3-diaryl-3-oxopropyl)-
cyclohexan-1-ones I under acidic conditions undergo
intramolecular heterocyclization to give tetrahydro-
chromenylium salts and that their carbocyclization
produces bridged bicyclic ketones. For example, di-
aryl-substituted 1,5-diketones I react with boron tri-
fluoride–ether complex or with dry hydrogen chloride
in acetic acid, yielding tetrahydrochromenylium tetra-
fluoroborates or chlorides, respectively [2, 3]. Bicyclo-
[3.2.1]oct-2-en-8-ones and bicyclo[3.3.1]non-2-en-9-
ones were formed as the major products when
2-(1,3-diaryl-3-oxopropyl)cyclopentan- and -cyclo-
hexan-1-ones were heated in boiling acetic acid in the
presence of hydrochloric acid [4, 5] (Scheme 1).
acid and acetic anhydride we obtained for the first time
mixtures of the corresponding 2,4-diaryl-5,6,7,8-tetra-
hydrochromenylium perchlorates IIa–IIc and 2,4-di-
arylbicyclo[3.3.1]non-2-en-9-ones IIIa–IIIc at differ-
ent ratios (Scheme 2, see table). The reaction at low
temperature gives mainly bicyclononenones IIIa and
IIIb; raising the temperature to 100°C reduces the
yield of compounds III, while the yield of chromenyli-
um salts II attains 60%.
It was presumed previously [6] that tetrahydro-
chromenylium salts are formed in reactions of
2-(1,3-diaryl-3-oxopropyl)cyclohexan-1-ones with
acid reagents through intermediate tetrahydrochro-
menes [6]. Our results suggest that the process under
study is mediated by bicyclo[3.3.1]non-2-en-9-ones
III. In fact, compounds IIIa and IIIb were converted
into the corresponding tetrahydrochromenylium per-
chlorates IIa and IIb in almost quantitative yield on
heating in AcOH–Ac2O in the presence of HClO4.
A probable mechanism involves protonation of the
By heating 2-(1,3-diaryl-3-oxopropyl)cyclohexan-
1-ones Ia–Ic with perchloric acid in a mixture of acetic
Scheme 1.
Ar
Ar
Ar
Ar
BF3 ·Et2O, HCl, AcOH
HCl, AcOH
BF4 (Cl–)
( )n
Ar
O
n = 0, 1
( )n
( )n
O
O
Ar
O
II
I
III
* For communication I, see [1].
1267

PCHELINTSEVA et al.
1268
Scheme 2.
Ar2
Ar2
Ar2
HClO4, AcOH, Ac2O
Ar1
O
ClO4
Ar1
+
O
O
O
Ar1
Ia–Ic
IIa–IIc
IIIa–IIIc
HClO4, AcOH, Ac2O, 100°C
IIa–IIc
IIIa–IIIc
Ar1 = Ar2 = Ph (a); Ar1 = Ph, Ar2 = 4-MeOC6H4 (b); Ar2 = 4-MeOC6H4, Ar2 = Ph (c).
carbonyl group in ketone III, opening of the unsatu-
rated carbocycle, and subsequent heterocyclization to
hexahydrochromene B. Deprotonation of B gives tetra-
hydrochromene C (Scheme 3), and the latter is trans-
formed into tetrahydrochromenylium salt according to
the known mechanism [6]. If the substituent at the
double bond (Ar1) in bicyclo[3.3.1]non-2-en-9-one III
possesses electron-donating properties, the salt forma-
tion is hindered because of positive charge delocaliza-
tion in carbenium ion A.
tetrahydridoaluminate [9], and reaction with hypophos-
phorous acid [10] were reported.
The spectral parameters of compounds IIIa–IIIc
were consistent with the assumed structure.
We also examined the relative reactivities of dif-
ferent reaction centers in unsaturated ketones IIIa and
IIIb toward electrophilic and nucleophilic reagents.
Halogenation of compound IIIa with chlorine or
bromine in carbon tetrachloride at room temperature
smoothly afforded the corresponding halogen-substi-
tuted bicyclononanones IVa and Va, indicating that the
bicyclic skeleton is stable under these conditions. By
Although bridged unsaturated ketone III (n = 0,
Ar1 = Ar2 = Ph) was synthesized for the first time as
early as almost 100 years ago [7] by passing hydrogen
chloride through a solution of 2-(3-oxo-1,3-diphenyl-
propyl)cyclopentan-1-one in alcohol, published data on
the structure and reactivity of such bicyclic systems are
very scarce. As noted in [5], bicycloalkenones like III
having more than five carbon atoms in the ring are
stable. The structure of ketones III was determined on
the basis of the IR data [8, 9], and the position of the
Scheme 3.
Ar2
Ar1
Ar2
H+
O
OH
Ar1
III
1
double C=C bond was proved by H NMR spectros-
Ar2
Ar2
Ar1
copy [10]. Such reactions of ketone III as hydrogena-
tion over palladium catalyst [8], reduction with lithium
OH
O
Yields of hetero- and carbocyclization products from car-
bonyl compounds Ia–Ic, IIIa, and IIIb
Ar1
A
Initial com-
pound no.
Temperature,
°C
Ar2
Ar2
Product (yield, %)
IIa (0) IIIa (16)
H
Ia
000
020
100
020
100
100
100
100
–H+
Ia
IIa (10)
IIa (27)
IIb (43)
IIb (60)
IIc (14)
IIa (90)
IIb (92)
IIIa (73)
IIIa (63)
IIIb (34)
IIIb (10)
IIIc (64)
–
O
Ar1
O
Ar1
Ia
B
C
Ib
Ar2
Ib
Ic
–H+
IIIa
IIIb
O
Ar1
–
II
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 9 2008

CHEMISTRY OF 1,5-DIKETONES. II.
1269
Scheme 4.
Cl
Ph
Cl2, CCl4
O
Cl
Ph
Cl
Cl
IVa
Ar2
Ar1
Br
Ph
Br
Br2, CCl4
O
O
Ph
IIIa, IIIb
Va
C6H4OMe-4
OH
NH2OH, EtOH
N
Ph
VIb
treatment of ketone IIIb with hydroxylamine in etha-
nol we obtained oxime VIb (Scheme 4). The structure
of halogenated ketones IVa and Va and oxime VIb
was confirmed by the IR and 13C NMR spectra.
identified by the melting point [11]. The filtrate was
evaporated, and the precipitate of bicyclo[3.3.1]non-2-
en-9-one IIIa–IIIc was filtered off, washed with
ethanol, and dried. The yields are given in table.
4-(4′-Methoxyphenyl)-2-phenyl-5,6,7,8-tetra-
hydrochromenylium perchlorate (IIb). Red crystals,
mp 196–198°C (reprecipitated from CHCl3 into Et2O).
IR spectrum, ν, cm–1: 2936 (CH2), 2855 (OCH3), 1540
(pyrylium), 1092 (ClO4–). Found, %: C 61.94; H 5.40;
Cl 8.10. C23H23ClO7. Calculated, %: C 61.82; H 5.19;
Cl 7.93.
EXPERIMENTAL
The H and 13C NMR spectra were recorded on
1
a Bruker MSL-400 spectrometer from solutions in
chloroform-d or DMSO-d6 using hexamethyldisiloxane
as internal reference. The IR spectra were measured on
a Specord M-80 spectrometer from samples dispersed
in mineral oil or hexachlorobutadiene. The progress of
reactions and the purity of products were monitored by
thin-layer chromatography on Silufol UV-254 plates
using hexane–diethyl ether–chloroform (4:1 :1) as
eluent; spots were detected by treatment with iodine
vapor. Initial 1,5-diketones Ia–Ic were synthesized ac-
cording to the procedure described in [4].
2-(4′-Methoxyphenyl)-4-phenyl-5,6,7,8-tetra-
hydrochromenylium perchlorate (IIc). Red–brown
crystals, mp 204–206°C (reprecipitated from CHCl3
into Et2O). IR spectrum, ν, cm–1: 2938 (CH2), 2855
(OCH3), 1540 (pyrylium), 1090 (ClO4–). Found, %:
C 62.24; H 5.30; Cl 8.00. C23H23ClO7. Calculated, %:
C 61.82; H 5.19; Cl 7.93.
2,4-Diphenylbicyclo[3.3.1]non-2-en-9-one (IIIa).
Colorless crystals, mp 144.5–145.5°C (from AcOH–
Ac2O, 5:1). IR spectrum, ν, cm–1: 2947 (CH2), 1712
(C=O), 1657 (C=C). 1H NMR spectrum, δ, ppm: 2.58–
2.81 m (6H, CH2), 5.51 s (1H, 4-H), 7.70–6.90 m
(10H, Harom), 7.86 s (1H, 3-H). 13C NMR spectrum, δC,
ppm: 16.91 (C7), 29.84 (C8), 31.74 (C6), 47.72 (C5),
48.70 (C1), 49.95 (C4), 125.61 (C3), 126.53–128.48
(Carom), 140.46 (C2), 212.9 (C9). Found, %: C 87.62;
H 7.11. C21H20O. Calculated, %: C 87.50; H 6.94.
Reaction of 2-(1,3-diaryl-3-oxopropyl)cyclo-
hexan-1-ones Ia–Ic with perchloric acid. Perchloric
acid (d = 1.69 g/cm3), 0.7 ml (0.012 mol), was added
under continuous stirring to a mixture of 0.005 mol of
compound Ia–Ic, 5.5 ml of glacial acetic acid, and
1 ml of acetic anhydride. The mixture was stirred at
room temperature or on heating until the conversion of
the initial diketone was complete, evaporated by half,
and poured into 150 ml of diethyl ether. The precipitate
was filtered off, washed with diethyl ether, and dried.
We thus isolated 2,4-diaryl-5,6,7,8-tetrahydrochro-
menylium perchlorates IIa–IIc. Perchlorate IIa was
4-(4′-Methoxyphenyl)-2-phenylbicyclo[3.3.1]-
non-2-en-9-one (IIIb). Colorless crystals, mp 171–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 9 2008

PCHELINTSEVA et al.
1270
172°C (from AcOH–Ac2O, 5:1). IR spectrum, ν, cm–1:
2934 (CH2), 2852 (OCH3), 1715 (C=O), 1654 (C=C).
1H NMR spectrum, δ, ppm: 2.21–1.30 m (6H, CH2),
3.97 s (3H, OCH3), 6.32 s (1H, 4-H), 7.76 s (1H, 3-H),
8.77–8.12 m (9H, Harom). 13C NMR spectrum, δC, ppm:
17.02 (C7), 29.71 (C8), 31.74 (C6), 47.76 (C5), 48.78
(C1), 49.87 (C4), 59.92 (CH3), 125.5–128.5 (Carom),
126.24 (C3), 140.56 (C2), 158.93 (C4′), 213.12 (C9).
Found, %: C 83.82; H 7.51. C22H22O2. Calculated, %:
C 82.88; H 6.96.
dropwise over a period of 0.5 h under stirring at room
temperature to a solution of 2.0 g (0.0064 mol) of
compound IIIa in carbon tetrachloride. The solution
was partially evaporated and cooled, and the precip-
itate was filtered off. Yield 2.0 g (64%), colorless crys-
tals, mp 167.5–168°C (from EtOH). IR spectrum, ν,
cm–1: 2955 (CH2); 1722 (C=O); 691, 520 (C–Br).
Found, %: C 56.88; H 4.80; Br 36.13. C21H20Br2O.
Calculated, %: C 56.28; H 4.50; Br 35.66.
4-(4′-Methoxyphenyl)-2-phenylbicyclo[3.3.1]-
non-2-en-9-one oxime (VIb). A solution of 0.25 g
(0.8 mmol) of compound IIIb and 0.14 g (2.1 mmol)
of hydroxylamine hydrochloride in 10 ml of anhydrous
ethanol was heated for 3.5 h on a boiling water bath.
The solution was cooled, and the precipitate was
filtered off. Yield 0.15 g (58%), colorless crystals,
mp 214–215°C (from EtOH). IR spectrum, ν, cm–1:
2920 (CH2); 2860, 2840 (NOH); 1620 (C=C); 1040
(OCH3). Found, %: N 3.65. C21H23NO. Calculated, %:
N 4.20.
2-(4′-Methoxyphenyl)-4-phenylbicyclo[3.3.1]-
non-2-en-9-one (IIIc). Colorless crystals, mp 128.5–
129°C (from AcOH–Ac2O, 5:1). IR spectrum, ν, cm–1:
2940 (CH2), 2855 (OCH3), 1710 (C=O), 1660 (C=C).
1H NMR spectrum, δ, ppm: 1.36–2.09 m (6H, CH2),
3.53 s (3H, OCH3), 6.52 s (1H, 4-H), 7.49 s (1H, 3-H),
7.26–7.57 m (9H, Harom). 13C NMR spectrum, δC, ppm:
17.26 (C7), 29.74 (C8), 31.63 (C6), 47.61 (C5), 48.82
(C1), 49.76 (C4), 54.85 (CH3), 126.16–130.53 (Carom),
136.9 (C3), 141.0 (C2), 158.9 (C4′), 213.0 (C9). Found,
%: C 83.16; H 6.86. C22H22O2. Calculated, %: C 82.88;
H 6.96.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 06-03-32667a).
2,4-Diphenyl-5,6,7,8-tetrahydrochromenylium
perchlorate (IIa). Perchloric acid, 1.2 g (0.7 ml,
0.012 mol), was added dropwise to a solution of 1.44 g
(0.005 mol) of compound IIIa in a mixture of 5.5 ml
of glacial acetic acid and 1.1 ml of acetic anhydride.
The mixture was heated for 14 h at 100°C, evaporated
by half, and poured into 50 ml of diethyl ether. The
precipitate was filtered off, washed with diethyl ether,
and dried. Yield 90%; the product was identified by the
melting point [11].
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13
2940 (CH2), 1720 (C=O), 680–630 (C–Cl). C NMR
spectrum, δC, ppm: 26.14 (C7), 30.41 (C8), 30.49 (C6),
39.66 (C5), 40.31 (C1), 46.31 (C4), 51.34 (C3), 51.45
(C2), 128.47–136.84 (Carom), 201.10 (C9). Found, %:
C 56.88; H 4.84; Cl 31.93. C21H18Cl4O. Calculated, %:
C 58.91; H 4.24; Cl 33.12.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 9 2008