Ionic hydrogenation of α,β-unsaturated ketones with cyclohexane in the presence of aluminum halides

Article abstract of DOI:10.1023/A:1013891616553

4-Methyl-3-penten-2-one, 3-hepten-2-one, 3-methyl-1-phenyl-2-buten-1-one, 4-(2,4-dichlorophenyl)-, 4-(4-hydroxyphenyl)-, 4-(4-methoxyphenyl)-, 4-(2-hydroxyphenyl)-, and 4-(4-dimethylaminophenyl)-3-buten-2-ones, and 3-(4-methoxyphenyl)-1-phenyl-2-propenone react with cyclohexane in the presence of excess aluminum chloride or aluminum bromide in CH₂Cl₂ or CH₂Br₂, respectively, at room temperature to form the corresponding saturated ketones in high yields. Using 4-phenyl-and 4-(4-methoxyphenyl)-3-buten-2-ones as examples, it was shown that the reaction pattern does not change in going from the Lewis acids AlCl₃, and AlBr₃ to proton-donor acid system CF₃SO₃H-SbF₅. The reactive intermediates are likely to be C-protonated complexes of α,β-unsaturated ketones with aluminum halides or their O,C-diprotonated analogs.

Full text of DOI:10.1023/A:1013891616553

Russian Journal of Organic Chemistry, Vol. 37, No. 11, 2001, pp. 1534 1541. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 11, 2001,
pp. 1610 1617.
Original Russian Text Copyright
2001 by Koltunov, Repinskaya, Borodkin.
Ionic Hydrogenation of , -Unsaturated Ketones
,
with Cyclohexane in the Presence of Aluminum Halides* **
K. Yu. Koltunov, I. B. Repinskaya, and G. I. Borodkin
Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090 Russia
e-mail: organic@fen.nsu.ru
Received July 10, 2000
Abstract 4-Methyl-3-penten-2-one, 3-hepten-2-one, 3-methyl-1-phenyl-2-buten-1-one, 4-(2,4-dichloro-
phenyl)-, 4-(4-hydroxyphenyl)-, 4-(4-methoxyphenyl)-, 4-(2-hydroxyphenyl)-, and 4-(4-dimethylaminophenyl)-
3-buten-2-ones, and 3-(4-methoxyphenyl)-1-phenyl-2-propenone react with cyclohexane in the presence of
excess aluminum chloride or aluminum bromide in CH2Cl2 or CH2Br2, respectively, at room temperature to
form the corresponding saturated ketones in high yields. Using 4-phenyl- and 4-(4-methoxyphenyl)-3-buten-
2-ones as examples, it was shown that the reaction pattern does not change in going from the Lewis acids
AlCl3 and AlBr3 to proton-donor acid system CF3SO3H SbF5. The reactive intermediates are likely to be
C-protonated complexes of , -unsaturated ketones with aluminum halides or their O,C-diprotonated analogs.
In continuation of our studies on acid-catalyzed
reactions of unsaturated compounds with weak nucleo-
philes we turned our attention to the reaction of
, -unsaturated ketones with alkanes. With 4-methyl-
3-penten-2-one (Ia) as an example we previously
demonstrated the possibility for hydride reduction of
enones with alkanes in the presence of Lewis acids
[1]. The reaction occurred under mild conditions and
resulted in formation of 4-methylpentan-2-one in
a good yield. Caustard et al. [2] reported on the reduc-
tion with methylcyclopentane of a double bond con-
jugated with a carbonyl group in some steroid com-
pounds in the superacid system HF SbF5. The goal
of the present work was to examine the reaction of
, -unsaturated ketones with alkanes in the presence
of aluminum halides. We studied the effect of the
reaction conditions, substrate structure, and nature of
the medium; the structure of the reactive intermediate
was also considered.
aluminum halide taken). In all cases the reactions
occurred at room temperature (Scheme 1).
4-Methyl-3-penten-2-one (Ia), 3-hepten-2-one (Ib),
and 3-methyl-1-phenyl-2-buten-1-one (Ic) were
smoothly reduced to 4-methyl-2-pentanone (IIa),
2-heptanone (IIb), and 3-methyl-1-phenyl-1-butanone
(IIc) in 65, 70, and 95% yield, respectively (Table 1).
It is seen that replacement of the methyl group in the
carbonyl moiety of enone Ia by phenyl (Ic) has no
appreciable effect on the reactivity. However, com-
parison of the reaction conditions for compound Ib,
on the one hand, and enones Ia and Ic, on the other,
shows an appreciable effect on their reactivity of the
structure of the olefin fragment.
The main pathway of the above reactions is hydride
ion transfer from cyclohexane to the substrate, which
leads to hydrogenation of the double carbon carbon
bond. The presence of a phenyl group in the olefin
moiety gives rise to a number of side processes. In the
reaction of 4-phenyl-3-buten-2-one (Id) with cyclo-
hexane in the presence of aluminum chloride (reaction
time 1 h) we obtained a complex mixture of products.
According to the GC MS data, this mixture contained
4-phenyl-2-butanone (IId), products of its mono- and
dialkylation with C6-cations, ketones III and IV
(which were formed as a result of elimination of
hydride ion from cyclohexane), and 4,4 -p-phenylene-
bis(2-butanone) (V). The ratio IId:III:IV:V was
2.3:1:2.3:6.3. Ketone V was isolated from the mix-
The reactions of , -unsaturated ketones were
carried out with excess cyclohexane and Lewis acid
(aluminum chloride or bromide), using methylene
chloride or bromide as solvent (depending on the
____________
*
For preliminary communication, see [1].
**
This study was financially supported by the Ministry of
General and Professional Education of the Russian Federa-
tion (project no. 164/97) and by the Integratsiya Federal
Special-Purpose Program (project no. A0051).
1070-4280/01/3711-1534$25.00 2001 MAIK Nauka/Interperiodica

IONIC HYDROGENATION OF , -UNSATURATED KETONES
1535
Scheme 1.
I, II, R1 = R2 = R3 = CH3 (a); R1 = CH3, R2 = H, R3 = C3H7 (b); R1 = C6H5, R2 = R3 = CH3 (c); R1 = CH3, R2 = H, R3 = C6H5 (d);
R1 = CH3, R2 = H, R3 = 2,4-Cl2C6H3 (e); R1 = CH3, R2 = H, R3 = 4-HOC6H4 (f); R1 = CH3, R2 = H, R3 = 4-CH3OC6H4 (g);
R1 = CH3, R2 = H, R3 = 2-HOC6H4 (h); R1 = C6H5, R2 = H, R3 = 4-CH3OC6H4 (i); R1 = CH3, R2 = H, R3 = 4-(CH3)2NC6H4 (j).
Scheme 2.
ture in the pure form. Presumably, it was formed by
reaction of ketone IId with enone Id [4] and subse-
quent elimination of phenyl group from the condensa-
tion product [5] and further hydrogentation of the
elimination product (Scheme 2).
It was reasonable to expect that introduction into
the phenyl group of the olefinic moiety of enone of
an electron-acceptor substituent or a substituent
capable of being converted into electron-acceptor one
via complex formation with aluminum halide (OR,
NR2, etc.) should hamper undesirable alkylation of
the aromatic ring. The results of our experiments
were in full agreement with the above expectations.
4-(2,4-Dichlorophenyl)-3-buten-2-one (Ie) was
smoothly reduced with cyclohexane in the presence of
excess aluminum chloride, yielding 87% of 4-(2,4-di-
chlorophenyl)-2-butanone. Enones having phenyl
groups with substituents which can be modified via
complex formation behaved similarly. 4-(4-Hydroxy-
phenyl)-3-buten-2-one (If), 4-(4-methoxyphenyl)-3-
buten-2-one (Ig), 4-(2-hydroxyphenyl)-3-buten-2-one
(Ih), and 3-(4-methoxyphenyl)-1-phenyl-2-propenone
Table 1. Reduction of , -unsaturated ketones Ia Ij with cyclohexanone in the presence of aluminum halides at room
temperature
Initial compound
Product
Acid system
Reaction time, h
Yield, %
Ia
Ib
Ic
Id
Ie
If
Ig
Ih
Ii
IIa
IIb
IIc
IId
IIe
IIf
IIg
IIh
IIi
AlCl3, CH2Cl2
AlBr3, CH2Br2
AlCl3, CH2Cl2
AlCl3, CH2Cl2
AlCl3, CH2Cl2
AlCl3, CH2Cl2
AlCl3, CH2Cl2
AlBr3, CH2Br2
AlCl3, CH2Cl2
AlBr3, CH2Br2
1
40
3
65a
70b
95
1
18c
87
30
15
3
3
3
95
90
60d
95
Ij
IIj
135
97
a
b
c
With pentane as reducing agent the reaction time was 48 h; yield 64%; conversion 78%.
In the presence of AlCl3 (CH2Cl2) the reaction time was 102 h; conversion 25% (according to the NMR data).
A complex mixture of products was obtained (see text).
d
The reaction in the presence of AlCl3 was accompanied by intramolecular cyclization of the substrate [3].
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

1536
KOLTUNOV et al.
Scheme 3.
Y = H, AlmHlg3m.
(Ii) were thus reduced to 4-(4-hydroxyphenyl)-2-
butanone (IIf), 4-(4-methoxyphenyl)-2-butanone (IIg),
4-(2-hydroxyphenyl)-2-butanone (IIh), and 3-(4-meth-
oxyphenyl)-1-phenyl-1-propanone (IIi) in 95, 90, 60,
and 95% yield, respectively. The complete reduction
of 4-(4-dimethylaminophenyl)-3-buten-2-one (Ij) in
the presence of aluminum bromide required keeping
of the reaction mixture for a long time (135 h), and
the yield of 4-(4-dimethylaminophenyl)-2-butanone
(IIj) was almost quantitative (Table 1).
The use of a cyclic alkane for reduction of , -un-
saturated ketones is not necessary. The reaction can
also be effected with an acyclic alkane. For example,
enone Ia was reduced with pentane in the presence
of aluminum chloride at room temperature. After 48 h,
the yield of ketone IIa was 64%, the conversion of
enone Ia being 78%.
isomers. In none of the cases products of reduction
of the carbonyl group to hydroxy were found (cf. [8]).
Our results indicate that aluminum halides effec-
tively catalyze ionic hydrogenation of the double
carbon carbon bond in , -unsaturated ketones,
except for the substrates containing in the olefinic
moiety an unsubstituted phenyl ring or a phenyl ring
having donor substituents. The high catalytic activity
of aluminum halides makes it possible to perform the
process at room temperature, attaining complete trans-
formation of the substrate. Taking into account that
alkanes are among the most accessible organic raw
materials, the reaction under study seems to be pro-
mising from the practical viewpoint as a convenient
method of reduction of the double C C bond in
enones, which is more advantageous than the other
methods [9].
Apart from saturated ketones, the reaction mixtures
in all cases contained isomeric hydrocarbons of the
general formula C12H22. These products were formed
by reaction of C6-cations with C6H12 cycloalkanes
(cyclohexane in acid medium exists as an equilibrium
mixture with methylcyclopentane, and cyclohexyl
cation, with methylcyclopentyl cations [6, 7]). In the
reaction mixture obtained from compound Id and
cyclohexane we detected (by GC MS) 11 C12H22
Another important aspect of the present study is
the way of transformation of , -unsaturated ketone
into a superelectrophilic species capable of abstracting
hydride ion from alkane. Like saturated ketones,
enones could readily give complexes of type A with
aluminum halides (Scheme 3, Y = AlmHlg3m) [10, 11].
Such complexes are structurally related to O-protonat-
ed ketones A (Y = H) which could be formed con-
currently to complex formation, taking into account
Scheme 4.
Id, R = H; Ig, IIg, R = OCH3.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

IONIC HYDROGENATION OF , -UNSATURATED KETONES
1537
Structures of dications E-1 and E-2 optimized by the MNDO/PM3 method. The bond lengths are given in
.
the presence in the reaction mixture of trace amounts
of a strong protic acid and the low basicity of enones
(pKBH ranges from 5 to 7 [12]).
enhanced acidity [14]. They were assumed to be inter-
mediates in reactions of naphthols and naphthyl ethers
with nonactivated arenes and alkanes [15, 16].
+
However, the electrophilicity of carboxonium ions,
and probably of the enone complexes, is insufficient
to abstract hydride ion from alkanes [8, 11]. The same
also follows from the results of our experiments with
enone Id and cyclohexane in strong protic acids.
According to the 1H NMR data, enone Id in CF3SO3H
(H0 = 14.1 [7]) at 25 C undergoes complete protona-
tion at the oxygen atom to give ion VI of type A
Probably, aluminum halides give rise mainly to
a similar kind of activation, namely complex forma-
tion between aluminum halide and enone and sub-
sequent C-protonation of the complex, leading to
structurally analogous intermediate dicationic species
B (Y = AlmHlg3m, Scheme 3). In both cases, super-
electrophilic intermediate B abstracts hydride ion from
alkane, yielding cation C. The latter is converted
into ketone II on treatment of the reaction mixture
with water.
Enones If Ij containing OH, OCH3, and N(CH3)2
groups in the benzene ring could be activated addi-
tionally via protonation or complex formation of
Lewis acid at the above groups, which should enhance
the electrophilicity of ions thus formed. For example,
in the reduction of enone Ig the superelectrophilic
intermediate may be C-protonated form coordinated
to aluminum halide through both oxygen atoms or
analogous tricationic species D.
(R1 = C6H5, R2 = R3 = CH3, Y = H), which does not
react with cyclohexane for at least 5 h. Addition of
SbF5 to a CF3SO3H SbF5 molar ratio of 1:1 leads
to disappearance of signals belonging to ion VI in
10 min. After appropriate treatment, the reaction
mixture was identical to that obtained previously in
the reaction of Id with cyclohexane in the presence
of aluminum chloride (see Experimental). Likewise,
enone Ig in the acid system CF3SO3H SbF5 (molar
ratio 2:1) at 25 C quickly reacted with cyclohexane,
affording ketone IIg in quantitative yield (Scheme 4).
Thus, superacidic medium (H0 < 14.1) is required
for ionic hydrogenation of , -unsaturated ketones,
indicating that a stronger electrophile than carboxo-
nium ion is necessary. We believe that in the presence
of a protic acid such a superelectrophile may be
O,C-diprotonated enone B (Y = H, Scheme 3). The
possibility for formation of such cationic species was
demonstrated by us previously using low-temperature
1H and 13C NMR spectroscopy with enones Ia and Id
as examples in the acid system HF SbF5 SO2FCl.
Therefore, O,C-diprotonated forms of , -unsaturated
ketones were postulated as reactive intermediates in
the reactions with arenes [13]. Structurally related
dicationic species were observed previously for 1- and
2-naphthol derivatives and the corresponding methyl
ethers (structures VII and VIII) in media with
Ohwada et al. [16] proposed an alternative path
of superelectrophilic activation of , -unsaturated
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

1538
KOLTUNOV et al.
Table 2. Calculated (MNDO/PM3) heats of formation ( Hf), charges on atoms, and energies of the frontier molecular
orbitals of dications E-1 and E-2
Dication
Hf, kcal/mol
HOMO, eV
LUMO, eV
q1
q2
q3
q4
qO
E-1
E-2
430.7
458.5
17.93
17.78
10.44
10.64
0.226
0.133
0.434
0.023
0.183
0.080
0.154
0.093
0.085
0.043
enones in reactions with another weak nucleophile,
benzene, in the acid system CF3SO3H SbF5 [16].
The reactive intermediates were assumed to be dica-
tions formed by addition of two protons to the enone
oxygen atom [16]. However, the formation of such
species was not confirmed experimentally [11, 16].
Probably, the dications are present in acid medium at
a very low equilibrium concentration or fast exchange
with the medium occurs. The participation of O,O-di-
protonated forms of enones in reactions with weak
nucleophiles can be substantiated on the assumption
that they are stronger electrophiles than the corre-
sponding O,C-diprotonated species. To verify this
assumption we performed MNDO/PM3 quantum-
chemical calculations [17] of the dications derived
from enone Id via protonation of the O and C atoms
(structure E-1) and double protonation of the oxygen
atom (E-2). The calculation results are presented in
Table 2, and figure shows the optimized geometries
of dications E-1 and E-2 (some bond lengths and
bond angles are also given). Unlike dication E-1,
the carbon and oxygen atoms in structure E-2 lie in
one plane. Dication E-1 is more stable than E-2 by
28 kcal/mol. The energies of the lowest unoccupied
molecular orbitals ( LUMO) are fairly similar. Taking
into account the higher stability of dication E-1 and
the greater positive charge on C4 therein, its formation
as reactive intermediate is more probable than the
formation of E-2.
G 1081-A system consisting of an HP 5890 Series II
gas chromatograph and an HP 5971 mass-selective
detector; energy of ionizing electrons 70 eV; HP-5
column, 30 m 0.25 mm 0.25 m, 5% of biphenyl
and 95% of dimethylsiloxane; carrier gas helium,
1 ml/min; oven temperature programming from 50 C
(2 min) at a rate of 10 C/min to 280 C (5 min);
injector temperature 280 C; ion source temperature
173 C. Quantum-chemical calculations were per-
formed by the MNDO/PM3 procedure [17] with full
geometry optimization using HyperChem 5.02 soft-
ware. The progress of reactions was monitored by
TLC on Silufol UV-254 plates; spots were visualized
with iodine vapor or under UV light; eluent hexane
ethyl acetate, 5:1. Ketones IIb, IIc, IIe, IIi, and IIj
were isolated by column chromatography on silica gel
using hexane ethyl acetate, 10:1. Aluminum bromide
of analytical grade and aluminum chloride and tri-
fluoromethanesulfonic acid from Merck were used.
Cyclohexane of chemically pure grade and reagent-
grade methylene chloride and methylene bromide
were distilled prior to use. Antimony pentafluoride
was distilled under atmospheric pressure in a stream
of argon. Enone Ia was synthesized by self-condensa-
tion of acetone; enones Ib, Id, Ie, Ig, Ih, and Ij were
prepared by condensation of acetone with butanal,
benzaldehyde, 2,4-dichlorobenzaldehyde, 4-methoxy-
benzaldehyde, 2-hydroxybenzaldehyde, and 4-(di-
methylamino)benzaldehyde, respectively, in the pres-
ence of a 10% solution of NaOH [18]. Enone Ii was
synthesized in a similar way by condensation of aceto-
phenone with 4-methoxybenzaldehyde. Compound If
was obtained by demethylation of Ig (a mixture of
Ig and aluminum bromide at a molar ratio of 1:3
in CH2Br2 was kept for 5 h at room temperature [19]).
Enone Ic was synthesized by bromination of 1-phenyl-
3-methyl-1-butanone with bromine and subsequent
dehydrobromination with 1,8-diazabicyclo[5.4.0]un-
dec-7-ene [18].
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded on
a Bruker DPX-250 spectrometer at 250.13 MHz for
1H and 62.9 MHz for 13C. The chemical shifts were
measured relative to the solvent signals (CDCl3,
7.28 ppm and
76.9 ppm). The chemical shifts
of cationic speciesCin acid solutions were measured
relative to tetramethylammonium tetrafluoroborate
( 3.2 ppm). Gas chromatographic mass spectrometric
analysis* was performed using a Hewlett Packard
____________
4-Methyl-2-pentanone (IIa). a. A suspension of
15 g (0.15 mol) of enone Ia, 27 g (0.2 mol) of
aluminum chloride, and 15 g (0.17 mol) of cyclo-
hexane in 40 ml of CH2Cl2 was stirred for 1 h at room
temperature. The mixture was poured onto ice, the
*
The authors are grateful to L.M. Pokrovskii for carrying out
the GC MS analysis.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

IONIC HYDROGENATION OF , -UNSATURATED KETONES
1539
products were extracted into ether, and the extract
was washed with water and dried over MgSO4. By
distillation we isolated 10 g (65%) of ketone IIa;
the H NMR spectral parameters of the product coin-
cided with those reported in [20].
b. An analogous experiment was carried out with
the same amounts of enone Ia and aluminum chloride
and 37 g (0.35 mol) of pentane. The mixture was
stirred for 48 h at room temperature and was then
treated as described above and analyzed by GLC.
The conversion of enone Ia was 78%, and the yield
of ketone IIa was 64% on the reacted enone.
143 (46.6), 131 (98.5), 117 (100), 105 (3.3), 91
(72.5), 83 (35.2) [C6H11], 55 (31.8) [CH3COCH2],
43 (91.5) [CH3CO], 41 (15.3). Mass spectrum of
ketone IV, m/z (Irel, %): 312 (71.6) M+, 187 (58.0),
171 (51.7), 161 (14.9), 143 (11.7), 141 (12.2), 129.1
(45.7), 115 (15.2), 105 (36.4), 91 (25.2), 83 (100), 55
(62.5), 43 (41.3) [CH3CO], 41 (23.5). Mass spectrum
1
of diketone V, m/z (Irel, %): 218 (13.7) M+, 175 (0.5),
+
+
[M CH3CO] , 160 (31.5), [M CH3COCH2] , 117
(100), 91 (115), 43 (59.3) [CH3CO].
The residue (see above) was distilled under reduced
pressure. A fraction with bp 124 128 C (3 mm)
crystallized; it was diketone V, mp 47 50 C (from
ethanol) [21]. 13C NMR spectrum, C, ppm: 29.03
(C1 ), 29.28 (C3 ), 44.67 (C2 ), 128.03 (C2, C3, C5, C6),
138.44 (C1, C4), 203.0 (C O).
2-Heptanone (IIb). A solution of 0.5 g (4 mmol)
of enone Ib, 3 g (10 mmol) of aluminum bromide,
and 2 g (20 mmol) of cyclohexane in 5 ml of CH2Br2
was kept for 40 h at room temperature. The mixture
was poured onto ice, and the organic layer was
washed with a solution of sodium carbonate and
water, and dried over MgSO4. The organic solution
was carefully evaporated, and the residue was sub-
jected to chromatography. We isolated 0.36 g (70%)
b. An NMR ampule was charged with 0.75 g
(0.005 mol) of CF3SO3H, 26 mg (3 mmol) of cyclo-
1
hexane, and 30 mg (2 mmol) of enone Id. The H
NMR spectrum of the solution showed the presence
of O-protonated enone Id, , ppm: 3.02 s (3H, CH3),
7.44 d (1H, CHCO, J = 15.3 Hz), 7.67 t (2H, 3 -H,
J = 7.77 Hz), 7.86 t (2H, 4 -H, J = 7.8 Hz), 8.03 d
(2 -H, J = 7.8 Hz), 8.98 d (1H, CHC6H5, J =
15.3 Hz). The spectrum did not change after keeping
the acid solution for 5 h at 25 C.
To the acid solution we added 1.1 g (0.005 mol) of
SbF5, and the mixture was stirred and, 10 min after,
poured onto ice. The organic phase was extracted
into ether, and the solvent and volatile components
were distilled off to obtain 35 mg of the residue
which, according to the GC MS data, contained
C12H22 hydrocarbons, ketones IId, III, and IV, and
diketone V; yield 9, 5, 2, and 84%, respectively.
1
of ketone IIb. The H NMR spectrum of the product
coincided with that reported in [20].
3-Methyl-1-phenyl-1-butanone (IIc). A suspen-
sion of 1 g (0.006 mol) of enone Ic, 2 g (0.015 mol)
of aluminum chloride, and 3 g (0.035 mol) of cyclo-
hexane in 15 ml of CH2Cl2 was stirred for 3 h at
room temperature. The mixture was poured onto ice,
and ketone IIc was isolated as described above for
1
compound IIb. Yield 0.97 g (95%). The H and 13C
NMR spectra of the product coincided with those
of an authentic sample.
Reaction of enone Id with cyclohexane. a. A sus-
pension of 1.46 g (0.01 mol) of enone Id, 6 g
(0.045 mol) of aluminum chloride, and 5 g (0.06 mol)
of cyclohexane in 25 ml of CH2Cl2 was stirred for
1 h at room temperature. The mixture was poured
onto ice and extracted with ether. The combined
extracts were dried over MgSO4 and carefully
evaporated, and the residue (2 g) was analyzed by
GC MS. It contained hydrocarbons of the general
formula C12H22 (total of 11 isomers), ketones IId, III,
IV, and diketone V; yield 18.6, 5.4, 9, and 67%,
respectively. Ketone IId was identified by comparing
its mass spectrum with that of an authentic sample;
isomeric C12H22 hydrocarbons and ketones III V
were identified by analyzing their mass spectra.
4-(2,4-Dichlorophenyl)-2-butanone (IIe). A sus-
pension of 0.3 g (0.001 mol) of enone Ie, 0.75 g
(0.006 mol) of AlCl3, and 1 g (0.012 mol) of cyclo-
hexane in 10 ml of CH2Cl2 was stirred for 30 h at
room temperature. It was then poured onto ice and
extracted with ether, and the extract was washed with
water and dried over MgSO4. The solvent and C6H12
alkanes were carefully distilled off, and the residue
was subjected to chromatography. We isolated 0.26 g
(87%) of ketone IIe. M+ 216.01115 (C10H10Cl2O).
1H NMR spectrum, , ppm: 2.16 s (3H, CH3), 3.62 m
(4H, CH2CH2), 7.15 br.s (2H, 5 -H, 6 -H), 7.36 br.s
(1H, 3 -H). 13C NMR spectrum, C, ppm: 27.03 (C4),
29.8 (C1), 42.77 (C3), 127.02 (C5 ), 129.14 (C6 ),
Mass spectrum of one of the C12H22 isomers, m/z
(Irel, %): 166 (70.8) M+, 151 (58.6), 137 (0.4), 123
(0.37), 109 (31.1), 95 (90.4), 81 (100), 67 (53.9),
55 (42.5), 41 (32.0). Mass spectrum of ketone III,
m/z (Irel, %): 230 (83.8) M+, 172 (99.7), 157 (15.0),
131.34 (C3 ), 132.5 (C4 ), 134.35 (C2 ), 137.05 (C1 ),
207.03 (C O).
4-(4-Hydroxyphenyl)-2-butanone (IIf). A suspen-
sion of 0.1 g (6 mmol) of enone If, 0.33 g (0.002 mol)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

1540
KOLTUNOV et al.
of aluminum chloride, and 0.8 g (0.009 mol) of cyclo-
hexane in 5 ml of CH2Cl2 was stirred for 15 h at
room temperature. The mixture was poured onto ice,
the products were extracted into ether, the extract was
treated with a 10% solution of NaOH, and the alkaline
solution was acidified and extracted with ether. The
extract was dried and evaporated to obtain 0.1 g
(95%) of ketone IIf, mp 81 83 C (from benzene) [3].
2. Caustard, J.M., Douteau, M.H., Jacquesy, J.C., and
Jacquesy, R., Tetrahedron Lett., 1975, no. 25,
pp. 2029 2030.
3. Berlin, A.L., Sherlin, S.M., and Serebrenniko-
va, T.A., Zh. Obshch. Khim., 1949, vol. 19, no. 3,
pp. 569 576.
4. Concos, R. and Friedman, B.S., Friedel Crafts and
Related Reactions, Olah, G.A., Ed., New York:
Interscience, 1964, vol. 1, part 1, pp. 289 412;
Roberts, R.M. and Khalaf, A., Friedel Crafts Alkyla-
tion Chemistry, New York: Marcel Dekker, 1984,
pp. 502 507, 623 660.
4-(4-Methoxyphenyl)-2-butanone (IIg). a. A sus-
pension of 1 g (0.006 mol) of enone IIg, 3 g
(0.022 mol) of AlCl3, and 3 g (0.035 mol) of cyclo-
hexane in 15 ml of CH2Cl2 was stirred for 3 h at room
temperature. The mixture was treated as described
above, volatile components were removed, and the
residue was subjected to chromatographic separation
to isolate 0.86 g (85%) of ketone IIg which was
5. Koptyug, V.A. and Bushmelev, V.A., Zh. Org.
Khim., 1968, vol. 4, no. 10, pp. 1822 1826;
Olah, G.A., Schlosberg, R.U., Porter, R.D.,
Mo, Y.K., Kolly, D.P., and Mateesku, G.D., J. Am.
Chem. Soc., 1972, vol. 94, no. 6, pp. 2034 2043.
1
identified by H NMR spectroscopy [20].
6. Nenitzescu, C.D. and Cantuniari, P., Chem. Ber.,
b. Enone Ig, 20 mg (1 mmol), was dissolved in
a mixture of 0.75 g (0.005 mol) of CF3SO3H and
0.54 g (2.5 mmol) of SbF5, and 20 mg (2 mmol) of
cyclohexane was added to the solution. After 5 min,
the mixture was poured onto ice. After appropriate
treatment, we isolated 16.2 mg (80%) of ketone IIg.
1933, vol. 66, no. 8, pp. 1097 1100.
7. Superacids, Olah, G.A., Prakash, G.K., and Som-
mer, J., Eds., New York: Wiley, 1985, p. 37.
8. Brower, D.M. and Kiffen, A.A., Recl. Trav. Chim.
Pays Bas, 1973, vol. 92, no. 5, pp. 689 697.
4-(2-Hydroxyphenyl)-2-butanone (IIh). A solu-
tion of 0.5 g (0.003 mol) of enone Ih, 3.5 g
(0.013 mol) of AlBr3, and 3 g (0.035 mol) of cyclo-
hexane in 10 ml of CH2Br2 was kept for 3 h at room
temperature. The mixture was treated as described
above for ketone IIf to isolate 0.3 g (60%) of product
IIh. mp 45 46 C (from petroleum ether).
3-(4-Methoxyphenyl)-1-phenyl-1-propanone
(IIi). A suspension of 1.2 g (0.005 mol) of enone
Ii, 4 g (0.03 mol) of aluminum chloride, and 3 g
(0.035 mol) of cyclohexane in 20 ml of CH2Cl2 was
stirred for 3 h at room temperature. The mixture was
treated as described above for compound IIg to
isolate 1.15 g (95%) of ketone IIh. mp 63 67 C
(from petroleum ether) [22].
4-(4-Dimethylaminophenyl)-2-butanone (IIj).
A solution of 0.38 g (0.002 mol) of enone Ij, 3.5 g
(0.013 mol) of aluminum bromide, and 2 g (0.02 mol)
of cyclohexane in 15 ml CH2Br2 was stirred for 135 h
at room temperature. The mixture was poured onto ice
and extracted with chloroform, and the extract was
washed with water and dried over MgSO4. Volatile
components were removed, and the residue was sub-
jected to chromatography to isolate 0.37 g (97%) of
ketone IIj. mp 48 51 C (from aqueous ethanol) [23].
9. Hudlicky, M., Reductions in Organic Chemistry,
New York: Wiley, 1984, pp. 119 122.
10. Thomas, C.A., Moshier, M.B., Morris, H.E., and
Moshier, R.W., Anhydrous Aluminum Chloride in
Organic Chemistry, New York: Reinhold, 1941.
Translated under the title Bezvodnyi khloristyi alyu-
minii v organicheskoi khimii, Moscow: Inostrannaya
Literatura, 1949, p. 119; Belen’kii, L.I., Gur’yano-
va, E.N., and Tovbin, Yu.K., Izv. Akad. Nauk SSSR,
Ser. Khim., 1974, pp. 2478 2485; Starowieyski, K.B.,
Pasynkiewicz, S., Sporzynski, A., and Chwojnow-
ski, A., J. Organomet. Chem., 1975, vol. 94, no. 3,
pp. 361 366; Starowieyski, K.B., Pasynkiewicz, S.,
and Sporzynski, A., J. Organomet. Chem., 1976,
vol. 117, no. 2, pp. 117 128.
11. Hartz, N., Rasul, G., and Olah, G.A., J. Am. Chem.
Soc., 1993, vol. 115, no. 4, pp. 1277 1285.
12. Mullen, K., Kotzamani, E., Schmickler, H., and
Frei, B., Tetrahedron Lett., 1984, vol. 25, no. 49,
pp. 5623 5626; Olah, G.A., Halpern, Y., Mo, Y.K.,
and Liang, G., J. Am. Chem. Soc., 1972, vol. 94,
no. 2, pp. 3554 3561; Zalewski, R.I. and Dunn, G.E.,
Can. J. Chem., 1969, vol. 47, no. 12, pp. 2263 2270.
13. Koltunov, K.Yu. and Repinskaya, I.B., Zh. Org.
Khim., 1994, vol. 30, no. 1, pp. 90 93.
14. Repinskaya, I.B., Shakirov, M.M., Koltunov, K.Yu.,
and Koptyug, V.A., Zh. Org. Khim., 1988, vol. 24,
no. 9, pp. 1907 1916; Koltunov, K.Yu., Shaki-
rov, M.M., Repinskaya, I.B., and Koptyug, V.A.,
Zh. Org. Khim., 1992, vol. 28, no. 5, pp. 1013 1023.
REFERENCES
1. Koltunov, K.Yu. and Repinskaya, I.B., Russ. J. Org.
Chem., 1995, vol. 31, no. 11, p. 1549.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001

IONIC HYDROGENATION OF , -UNSATURATED KETONES
1541
15. Repinskaya, I.B., Koltunov, K.Yu., Shakirov, M.M.,
Shchegoleva, L.N., and Koptyug, V.A., Zh. Org.
Khim., 1993, vol. 29, no. 5, pp. 972 981; Koltu-
nov, K.Yu., Repinskaya, I.B., Shakirov, M.M., and
Shchegoleva, L.N., Zh. Org. Khim., 1994, no. 30,
no. 1, pp. 82 89; Koltunov, K.Yu., Subbotina, E.N.,
and Repinskaya, I.B., Russ. J. Org. Chem., 1997,
vol. 33, no. 5, pp. 689 693; Koltunov, K.Yu.,
Shakirov, M.M., and Repinskaya, I.B., Russ. J.
Org. Chem., 1998, vol. 34, no. 4, pp. 595 596;
Koltunov, K.Yu., Ostashevskaya, L.A., and Repin-
skaya, I.B., Russ. J. Org. Chem., 1998, vol. 34,
no. 12, pp. 1796 1797.
18. Tietze, L.-F. and Eicher, T., Reactions and Syntheses
in the Organic Chemistry Laboratory, Mill Valley,
California: University Science Books, 1989. Tran-
slated under the title Preparativnaya organicheskaya
khimiya, Moscow: Mir, 1999, p. 69.
19. Protective
Groups
in
Organic
Chemistry,
McOmie, J.F.W., Ed., London: Plenum, 1973.
Translated under the title Zashchitnye gruppy
v organicheskoi khimii, Moscow: Mir, 1976, p. 174.
20. Sadtler Standart Spectra. NMR 1H Spectra, Phila-
delphia: Sadtler Research Laboratories.
21. Beilsteins Handbuch der organischen Chemie, EIV,
vol. 7, part 4, p. 3536.
16. Ohwada, T., Yamagata, N., and Shudo, K., J. Am.
Chem. Soc., 1991, vol. 113, no. 4, pp. 1364 1373.
22. Beilsteins Handbuch der organischen Chemie, EII,
vol. 8, p. 203.
17. Stewart, J.P., J. Comput. Chem., 1989, vol. 10, no. 2,
23. Beilsteins Handbuch der organischen Chemie, EII,
pp. 209 220.
vol. 14, p. 41.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001