Quantum chemical study of the electronic structure and reactivity of complexes of 4-oxo-4-(2-thienyl)- and 4-(5-methyl-2-thienyl)-4-oxobutyryl chlorides with aluminum chloride

Article abstract of DOI:10.1007/s11172-013-0085-2

The geometry and electronic structures of complexes of 4-oxo-4-(2-thienyl)- and 4-oxo-4-(5-methyl-2-thienyl)butyryl chlorides with aluminum chloride, as well as the corresponding carbocations, were studied in terms of the density functional theory (DFT) u

Full text of DOI:10.1007/s11172-013-0085-2

Russian Chemical Bulletin, International Edition, Vol. 62, No. 3, pp. 634—639, March, 2013
634
Quantum chemical study of the electronic structure and reactivity
of complexes of 4ꢀoxoꢀ4ꢀ(2ꢀthienyl)ꢀ and 4ꢀ(5ꢀmethylꢀ2ꢀ
thienyl)ꢀ4ꢀoxobutyryl chlorides with aluminum chloride*
L. I. Belen´kiia and V. I. Smirnovb
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: libel31@mail.ru
bM. V. Lomonosov University of Fine Chemical Technologies,
86 prosp. Vernadskogo, 119571 Moscow, Russian Federation.
Eꢀmail: mitht406@mail.ru
The geometry and electronic structures of complexes of 4ꢀoxoꢀ4ꢀ(2ꢀthienyl)ꢀ and 4ꢀoxoꢀ4ꢀ
(5ꢀmethylꢀ2ꢀthienyl)butyryl chlorides with aluminum chloride, as well as the corresponding
carbocations, were studied in terms of the density functional theory (DFT) using the B3LIP/6ꢀ
311+G(2d,p) method and the semiempirical PM6 method. An analysis of the relative energies
of the complexes and cations made it possible to interpret side reactions accompanying the
acylation of thiophenes with succinyl dichloride.
Key words: quantum chemical calculations, PM6 method, density functional theory (DFT),
B3LYP functional, electrophilic substitution.
1,4ꢀDi(2ꢀthienyl)butaneꢀ1,4ꢀdiones are key comꢀ
through complexes of ketoacid chlorides 2а—с with
Lewis acids, were considered.5 The influence of the
Friedel—Crafts acylation conditions and the relative
amount and nature of the Lewis acid on the ratio and
yields of formed 1,4ꢀdi(2ꢀthienyl)ꢀ1,4ꢀdiones 3а—с and
4ꢀoxoꢀ4ꢀ(2ꢀthienyl)butyric acids 4а—с was shown. The
earlier unknown direction of transformations in the sysꢀ
tem thiophene compound—succinyl dichloride—AlCl3
was found and its products were isolated: 4,4ꢀdi(2ꢀthiꢀ
enyl)butꢀ3ꢀenoic acids 5a—c, whose formation can easily
be presented as a result of alkylation of thiophene 1а—с
involving the keto group of acid chloride 2а—с or acid
4а—с followed by dehydration.
The ability of acids 5а—с to ringꢀchain tautomerism,
which is known for the benzene analogs, makes it possible
to explain the presence (discovered in Ref. 5) of 4,4ꢀdi(2ꢀ
thienyl)ꢀsubstitutedꢀbutyrolactones 6а—с in mixtures of
the reaction products (Scheme 1). Another possible route
for the formation of lactones 6 was considered.6 This route
includes consecutive transformations of acid chlorides 2
into acylium cations 7 and cyclization of the latter into
carbocations 8, whose reaction with thiophenes 1 can result
in the formation of compounds 6 without an intermediate
formation of unsaturated acids 5 (Scheme 1).
pounds in the synthesis of 2,5ꢀdi(2ꢀthienyl)pyrroles, 2,5ꢀ
di(2ꢀthienyl)furans, and the corresponding 2,2´:5´,2ꢀterꢀ
thiophenes (terthienyls), which are actively studied and
used in the recent years for the preparation of organic
polymers and semiconductors (see review1). A number of
methods for synthesis of 1,4ꢀdi(2ꢀthienyl)butaneꢀ1,4ꢀdiꢀ
ones is described, and the most part of them is multistage
(if starting from the corresponding thiophenes). In our
opinion, the most promising method for the synthesis of
1,4ꢀdithienylbutaneꢀ1,4ꢀdiones is the oneꢀstage acylation
of the corresponding thiophenes with succinyl chloride.
However, this reaction under the standard (for comꢀ
pounds of the thiophene series) conditions, i.e., using
SnCl4 as a condensing agent, after usual treatment affords
only the monoacylation product: 4ꢀoxoꢀ4ꢀ(2ꢀthienyl)ꢀ
butyric acid.2 1,4ꢀDi(2ꢀthienyl)butaneꢀ1,4ꢀdione has sucꢀ
cessfully been obtained for the first time from thiophene
and succinyl chloride by acylation in the presence of aluꢀ
minum chloride.3 Nevertheless, the yields of target diꢀ
ketones almost never exceeded 50% of the theoretical vaꢀ
lue.4,5 We studied5 reasons for such modest yields.
The reactions of thiophene and 2ꢀmethylꢀ and 2ꢀbromoꢀ
thiophenes (1а—с) with succinyl dichloride in the presꢀ
ence of AlCl3, TiCl4, and SnCl4, which proceed, evidently,
According to Scheme 1, the first stage of the processes
discussed is common for the formation of both target
products (diketones of type 3) and byꢀproducts 4—6.
This stage of a classical Friedel—Crafts acylation results
* Dedicated to the Academician of the Russian Academy of
Sciences I. P. Beletskaya on the occasion of her birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 0633—0638, March, 2013.
1066ꢀ5285/13/6203ꢀ634 © 2013 Springer Science+Business Media, Inc.

Electronic structure and reactivity
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
635
Scheme 1
R = H(a), Me (b), Br (c)
(after usual treatment of the reaction mixture) in the exꢀ
pected keto acids of type 4. Substantial distinctions are
observed at the second stage. They are due to different
transformations of intermediates, acid chlorides 2 (in the
form of complexes with AlCl3): diketones 3 are formed
in the standard reaction with the second molecule of
thiophene compound 1 and require the participation of an
nvꢀcomplex in which the AlCl3 molecule is bound to the
Cl atom or the O atom of the chlorocarbonyl group (this
nvꢀcomplex can be considered as a precursor of the correꢀ
sponding acylium ion), while the formation of unsaturatꢀ
ed acids of type 5 assumes the intermediate formation of
hydroxy acid 9 due to the alkylation of thiophene involvꢀ
ing a complex of acid chloride 2 with AlCl3 at the O atom
of the carbonyl group. Finally, lactones of type 6 can be
formed either by the intramolecular addition of COOH
group to the C=CH bond of acids 5, or through the inꢀ
tramolecular Oꢀacylation of acid chloride 2 accompanied
by the attack of the formed cation 8 (counterion AlCl4– is
omitted in Scheme 1) to the second molecule of thiophene
or its derivative.
formed in terms of the density functional theory (DFT)
using the B3LYP hybrid functional by the B3LYP/6ꢀ
311+G(2d,p) method and in the PM6 semiempirical apꢀ
proximation.
The results of this study allow one to conclude about
the preferential localization of the AlCl3 molecule at one
of the carbonyl O atoms or at the Cl atom. The bond
lengths calculated by both methods almost coincide and
agree with the known data on bond lengths in compounds
of diverse elements, including ordinary С—С bonds beꢀ
Results and Discussion
In this work, the quantum chemical study of the isoꢀ
meric nvꢀcomplexes of acid chlorides 2a and 2b with aluꢀ
minum chloride, viz., compounds 10a,b—12a,b, was perꢀ
tween atoms with different hybridization (Csp3—Csp
,
3
Csp3—Csp2, Csp2—Csp2), which are present in objects of our

636
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
Belen´kii and Smirnov
Table 1. Selected bond lengths (d) in complexes 10a,b—12a,b
calculated by the B3LYP/6ꢀ311+G(2d,p) method
results obtained by the B3LYP/6ꢀ311+G(2d,p) method.
As shown,8,9 reliable calculations of geometric and energy
parameters are possible in terms of the DFT method when
using the B3LYP hybrid functional for fiveꢀmembered
heterocyclic compounds with one heteroatom. These calꢀ
culations make it possible to interpret the reactivity of the
compounds, particularly, the directivity of the electroꢀ
philic substitution reactions.
The structural characteristics of the most important
(in the framework of the present study) fragments of comꢀ
pounds 10a,b—12a,b, viz., aliphatic chains Cl—C(O)—
CH2—CH2—C(O)— including the C(4)—C(5) bond and
bonds of coordinated AlCl3 molecules, calculated by the
B3LYP/6ꢀ311+G(2d,p) method are presented in Tables
1—3. The С—Н bond lengths ranging, in all cases, from
1.08 to 1.10 Å are omitted. Tables 2 and 3 include
the bond and dihedral angles that characterize the geoꢀ
metric and conformational peculiarities of these aliphatic
fragments.
Bond
d/Å
10a
10b
11a
11b
12a
12b
C(1)—С(2)
C(1)—O(1)
C(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(4)—O(2)
C(1)—Cl(1)
Al—O(1)
1.47 1.48 1.49
1.15 1.15 1.22
1.54 1.52 1.52
1.53 1.53 1.53
1.46 1.45 1.46
1.22 1.22 1.22
2.12 2.14 1.75
1.49 1.51 1.51
1.22 1.18 1.18
1.53 1.55 1.54
1.53 1.50 1.51
1.46 1.43 1.42
1.22 1.26 1.26
1.75 1.82 1.82
—
—
—
—
1.94
—
1.94
—
—
—
Al—O(2)
1.87 1.87
Al—Cl(1)
Al—Cl(2)
Al—Cl(3)
Al—Cl(4)
2.24 2.37
—
—
—
—
2.14 2.13 2.12
2.11 2.13 2.13
2.01 2.11 2.13
2.12 2.14 2.13
2.11 2.12 2.12
2.13 2.14 2.14
A characteristic feature of complexes 10a,b and 11a,b
is an almost planar zigzag conformation of the C(1)—
C(2)—C(3)—C(4)—С(5) chain, and the O(1)—C(1)—
Cl(1)—Al and C(1)—O(1)—Al—Cl(2) fragments substanꢀ
tially deviate from the plane of this carbon chain. On the
contrary, in complexes 12a,b the C(1)—C(2)—C(3)—
C(4)—С(5) chain does not lie in one plane, which is unꢀ
study.7 At the same time, some values of bond and diꢀ
hedral angles calculated by the PM6 method noticeably
differ from those obtained by the more perfect B3LYP/6ꢀ
311+G(2d,p) method.
Therefore, in further considerations of the calculated
structural and energy characteristics, we used only the
Table 2. Bond angles () in complexes 10a,b—12a,b calculated by the B3LYP/6ꢀ311+G(2d,p) method
Angle
/deg
11a 11b
Angle
/deg
10a
10b
12a
12b
11a
11b
12a
12b
O(1)—C(1)—Cl(1) 110.3 113.1 116.4 116.3 120.7 120.6
O(1)—C(1)—C(2) 139.0 139.9 124.6 124.6 126.4 124.5
Cl(1)—C(1)—C(2) 110.7 106.8 119.0 119.0 120.7 112.9
O(2)—C(4)—C(3) 120.2 120.2 120.7 120.7 121.3 121.0
O(2)—C(4)—C(5) 122.3 122.7 121.9 122.0 118.0 118.1
C(1)—O(1)—Al
O(1)—Al—Cl(2)
O(1)—Al—Cl(3)
O(1)—Al—Cl(4)
C(4)—O(2)—Al
O(2)—Al—Cl(2)
O(2)—Al—Cl(3)
O(2)—Al—Cl(4)
137.3 137.6
102.6 102.7
100.8 100.8
100.8 100.8
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
141.5 142.1
103.1 104.3
102.8 103.5
104.2 103.1
C(1)—Cl(1)—Al
Cl(1)—Al—Cl(2)
Cl(1)—Al—Cl(3)
Cl(1)—Al—Cl(4)
121.6 126.6
103.7 102.2
100.2 102.9
103.2 102.2
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Table 3. Selected dihedral angles () in complexes 10a,b—12a,b calculated by the B3LYP/6ꢀ311+G(2d,p) method
Angle
/deg
10a
Angle
/deg
11a 11b
0.0 0.0 C(5)—C(4)—O(2)—Al
Angle
/deg
12a 12b
10b
O(1)—C(1)—Cl(1)—Al
C(2)—C(1)—Cl(1)—Al
C(1)—Cl(1)—Al—Cl(2)
C(1)—Cl(1)—Al—Cl(3)
C(1)—Cl(1)—Al—Cl(4)
C(1)—C(2)—C(3)—C(4) 160.6
С(2)—С(3)—С(4)—С(5) 160.8
O(2)—C(4)—C(5)—C(6) 175.6
169.2
–10.4
44.8
83.8
–99.4
104.4
C(2)—C(1)—O(1)—Al
C(1)—O(1)—Al—Cl(2)
C(1)—O(1)—Al—Cl(3) –59.3 –59.4 C(4)—O(2)—Al—Cl(3) –166.5 103.5
C(1)—O(1)—Al—Cl(4) 59.4 59.4 C(4)—O(2)—Al—Cl(4) –46.0 –163.8
O(2)—C(4)—C(5)—C(6) 180.0 180.0 O(2)—C(4)—C(5)—C(6) 179.3
C(1)—C(2)—C(3)—C(4) 180.0 180.0 C(1)—C(2)—C(3)—C(4) 167.9
С(2)—С(3)—С(4)—С(5) 180.0 180.0 С(2)—С(3)—С(4)—С(5)
172.6 172.8
73.5 –43.5
180.0 180.0 C(4)—O(2)—Al—Cl(2)
166.1 –134.6
–73.6
–12.7
175.5
176.9
177.6
79.3
92.1
95.7
92.1

Electronic structure and reactivity
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
637
Table 5. Total (Etot) and relative (Erel) energies of cations
7a,b and 8a,b and complexes 10a,b—12a,b (R = H(a),
Me(b)) calculated by the B3LYP/6ꢀ311+G(2d,p) method
ambiguously a consequence of steric effect caused by the
presence of the bulky residue AlCl3.
We also calculated "open" carbocations 7a,b, which
can be considered as intermediates in the synthesis of tarꢀ
get diketones 3a,b, and "closed" cations 8a,b, which are
possible intermediates in the formation of unsaturated acꢀ
ids 5a,b and lactones 6a,b (Table 4).
Compound
Erel/kcal mol–1
Etot/Hartree
7a
7b
8a
28.58
29.67
0
—
—
–857.60429
8b
0
–896.94324
10a
10b
11a
11b
12a
12b
18.78
19.43
10.38
11.69
0
—
—
—
—
–2941.48902
–2980.82294
0
It should be mentioned that in "open" cations 7a,b the
C(2)—C(3)—C(4)—C(5) fragment lies as a zigzag in nearly
one plane, whereas the O(1)—C(1) bond is approximately
perpendicular to the plane of zigzag. In "closed" cations
8a,b two fiveꢀmembered rings are almost coplanar.
As should be expected according to published data,8 it
is difficult to interpret the calculated charges on atoms.
The relative energies (E) of complexes 10—12 and
cations 7 and 8 calculated by the B3LYP/6ꢀ311+G(2d,p)
method are given in Table 5. An analysis of these enerꢀ
gies made it possible to interpret side reactions accomꢀ
panying the acylation of thiophenes with succinyl diꢀ
chloride. Note that the PM6 method gives close values of
relative energies.
Among complexes 10a,b—12a,b, forms 12a,b with
AlCl3 molecule localization at the carbonyl O atom of the
ketone groups are energetically preferential rather than
their isomers 10a,b and 11a,b, in which the AlCl3 moleꢀ
cule is bound to the Cl atom or the O atom of the chloroꢀ
carbonyl group. Similarly, among cations 7 and 8, not
open forms 7a,b but their closed isomers 8a,b, in which
the positive charge is localized on the С(4) atom of the
lactone cycle, are preferable. These are complexes 12 and
cations 8 which are natural intermediates in the synthesis
of "anomalous" products, unsaturated acids 5 and lacꢀ
tones 6 (see Scheme 1).
By considering possible transformations in the system
thiophene compound—succinyl dichloride—AlCl3 preꢀ
sented in Scheme 1, one can explain remained unclear low
yield of diketone 3b from the most active of model subꢀ
strates, 2ꢀmethylthiophene, compared to diketones 3a,c
formed from less reactive thiophene and 2ꢀbromothioꢀ
phene: it is enough to assume that the alkylation reactions
2  5 and 2  6 are accelerated, in the case of reactive
methylthiophene, to a greater extent than acylation 2  3.
Indeed, it is easily seen from published data5 that 0.7 mole
of acid 5а and lactone 6a (totally) and 0.2 mole of acid 5с are
formed from thiophene and 2ꢀbromothiophene per 1 mole
of diketones 3а and 3с under the same conditions optimum
for the preparation of diketones (molar ratio AlCl3 : succiꢀ
nyl chloride = 6, temperature 40 С, reaction time 12 h),
whereas in the case of 2ꢀmethylthiophene the amount of
acids and lactones attains already 1.2 moles per 1 mole of
diketone 3b. Note that this is the enhanced (over other
thiophenes) formation of unsaturated acid from 2ꢀmethylꢀ
thiophene that made it possible to identify acid 5b in the
mixture and also isolate it in the individual state.5
Table 4. Selected bond lengths (d) and bond () and dihedral ()
angles in cations 7a,b—8a,b calculated by the B3LYP/6ꢀ
311+G(2d,p) method
Parameter
Bond
7a
7b
8a
8b
d/Å
C(1)—O(1)
С(1)—О(2)
C(1)—C(2)
C(4)—O(2)
С(2)—С(3)
C(3)—C(4)
C(4)—C(5)
1.21
—
1.12
—
1.16
1.50
1.50
1.53
1.28
1.50
1.39
1.17
1.49
1.51
1.53
1.31
1.51
1.38
1.42
1.22
1.55
1.55
1.44
1.40
1.23
1.55
1.55
1.43
Angle
/deg
135.4
O(1)—C(1)—C(2)
C(1)—C(2)—C(3)
C(2)—C(3)—C(4)
O(2)—C(4)—C(3)
O(2)—C(4)—C(5)
C(1)—O(2)—C(4)
178.2
114.5
105.0
117.5
123.6
—
178.5
114.6
104.7
117.2
124.4
—
134.7
105.7
104.1
112.6
119.5
111.0
105.9
104.3
112.9
119.4
110.9
Since the total yields of compounds of type 3, 5, and 6
range from 65 to 79%, we cannot rule out the possibility of
formation, under the reaction conditions, of other byꢀ
products that can be formed first of all from acids 5 or
their chlorides and from lactones 6. Similar transformaꢀ
tions leading to 4ꢀphenylꢀ1ꢀnaphthol are well known
/deg
85.7 –179.9 –180.0
0.0 0.0
180.0 –180.0
179.9 0.0 0.0
O(1)—C(1)—C(2)—C(3) –83.6
C(1)—C(2)—C(3)—C(4) 134.1 –132.2
C(2)—C(3)—C(4)—C(5) 170.0 –170.8
O(2)—C(4)—C(5)—C(6)
–1.0

638
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
Belen´kii and Smirnov
Scheme 2
Conditions: i. PCl3 or ; ii. PCl3 or Ac2O.
for the benzene analogs according to Borsche´s data10
(Scheme 2) and can easily be interpreted as a result of
intramolecular acylation. The transformation of 4,4ꢀdiꢀ
phenylbutyrolactone described in the same article is
evidently the result of the above mentioned ringꢀchain
tautomerism between lactone and unsaturated acid. In
work,11 4,4ꢀdiphenylbutꢀ3ꢀenoic acid or its ethyl ester was
transformed into 4ꢀphenylꢀ1ꢀnaphthol by the action of zinc
chloride. At the same time, it should be kept in mind that
the high reactivity of thiophenes can yield polycondensaꢀ
tion (resinification) products under drastic conditions.
Finally, let us consider the factors that prevent the
second stage of the reaction to occur, i.e., acylation of
thiophenes 1а—с with 4ꢀoxoꢀ4ꢀthienylbutyryl chlorides
2а—с in the presence of Lewis acids of medium strength,
such as tin and titanium tetrachlorides, but allow this
acylation to occur in the presence of a stronger acid,
aluminum chloride. An apparently similar situation is obꢀ
served when thiophenes react with ꢀhaloalkanoic acid
chlorides, in particular, chrloroacetyl chloride.
It was shown12 that chloroacetyl chloride, which is
a weaker base than alkanoyl chlorides, does not almost
form an nvꢀcomplex with tin tetrachloride and, therefore,
requires to use a stronger Lewis acid, aluminum chloride.
The necessity to perform acylation of alkylthiophenes in
the presence of AlCl3 in the case of oxalyl chloride13,14
and squaric acid dichloride15,16 was explained similarly.
A similar explanation is natural for compounds in which
the basicity of the chlorocarbonyl group can decrease beꢀ
cause of the negative inductive and/or resonance effects of
the adjacent substituent but does not appropriate for the
interpretation of the behavior of succinyl chloride, since
in its molecule the electronꢀwithdrawing groups are sepaꢀ
rated by the dimethylene fragment and, in addition, the
first stage of acylation proceeds normally in the presence
of SnCl4 and TiCl4.
and titanium are capable of forming complexes with the
coordination number 6; i.e., in the considered cases, we
cannot exclude the formation of a sevenꢀmembered comꢀ
plex in which the MCl4 molecule accept as ligands two
carbonyl groups belonging to the same succinyl dichloride
molecule.
In connection to the aforesaid, we should consider
changes in the behavior of acid dichlorides
ClCO(CH2)nCOCl with an elongation of the distance
between the chlorocarbonyl groups. The formation of 5,5ꢀdiꢀ
(2ꢀthienyl)pentaneꢀ1,5ꢀdione under the Friedel—Crafts
conditions has first been described17 in 1955. This diketone
was isolated in a yield of 5% when ethyl 4ꢀ(2ꢀthenoꢀ
yl)butyrate was distilled, which was explained by the presꢀ
ence of an admixture of glutaryl dichloride in the acylating
agent (halfꢀester of glutaryl chloride). It should be menꢀ
tioned that almost the same yield of diketone was obtained
by us under similar conditions (see Experimental) when
using glutaryl dichloride, and the major identified product
was 4ꢀ(2ꢀthenoyl)butyric acid, i.e., glutarodichloride and
succinodichloride strongly resemble each other in behavꢀ
ior in the presence of tin tetrachloride.
However, whether the article17 remained unnoticed or
its results did not inspired other chemists, but no descripꢀ
tion of the synthesis of 1,5ꢀ(2ꢀthienyl)pentaneꢀ1,5ꢀdione
by the reaction of glutarodichloride with thiophene was
found during almost subsequent 60 years, although synꢀ
theses of this diketone by other methods were carried
out,18—20 as well as the Friedel—Crafts syntheses in the
presence of AlCl3, in which substituted 1,5ꢀbis(3ꢀthienyl)ꢀ
pentaneꢀ1,5ꢀdiones successfully used as intermediates for
the preparation of photochromic dithienylethenes were
obtained in high yields.21,22
The situation is substantially different for adipodichlorꢀ
ide, which smoothly acylates thiophene in the presence of
tin tetrachloride to form 1,6ꢀdi(2ꢀthienyl)hexaneꢀ1,6ꢀdiꢀ
one (83% yield).23 There are data24 on thiophene acylaꢀ
tion with succinic anhydride and polyanhydride of higher
dicarboxylic acids HOOC(CH2)nCOOH, n = 4, 6—8 in
the presence of SnCl4. In the case of succinic anhydride
and adipinic polyanhydride, only the corresponding keto
acids were obtained, which is quite expectable for anꢀ
hydrides. On the contrary, both keto acids and diketones
Based on the results of quantum chemical calculations
performed in this work, in particular, on the geometric
characteristics of complexes 12a,b, one can assume that
the second acylation stage is impeded by steric factors:
shielding of the chlorocarbonyl group with the Lewis acid
bound in a complex at the carbonyl group. Note that,
unlike aluminum chloride, compounds of tetravalent tin

Electronic structure and reactivity
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
639
8. L. I. Belen´kii, T. G. Kim, I. A. Suslov, N. D. Chuvylkin,
Russ. Chem. Bull. (Int. Ed.), 2005, 54, 853 [Izv. Akad. Nauk,
Ser. Khim., 2005, 837].
9. L. I. Belen´kii, N. D. Chuvylkin, I. D. Nesterov, Russ. Chem.
Bull. (Int. Ed.), 2011, 60, 2205 [Izv. Akad. Nauk, Ser. Khim.,
2011, 2163].
are formed from polyanhydrides of higher dicarboxylic
acids (n = 6—8), which is difficult for interpretation.
Thus, side reactions that accompany the acylation of
thiophenes with succinyl dichloride were interpreted by
the quantum chemical calculations. The energy preferꢀ
ence of nvꢀcomplexes with aluminum chloride at the keꢀ
tone carbonyl group in the intermediate formed at the first
stage of acylation, 4ꢀoxoꢀ4ꢀ(2ꢀthienyl)butyryl chloride, was
shown. This should favor the formation of byꢀproducts:
4,4ꢀdithienylbutꢀ3ꢀenoic acids and 4,4ꢀdi(2ꢀthienyl)ꢀsubꢀ
stituted ꢀbutyrolactones. The reactions of succinyl, gluꢀ
taryl, and adipinyl chlorides with thiophene were comꢀ
pared. The results of the comparison do not contradict our
assumption about the steric shielding of the chlorocarboꢀ
nyl group in 4ꢀoxoꢀ4ꢀ(2ꢀthienyl)butyryl chloride, with the
SnCl4 or TiCl4 complex at the ketone group of the same
acid chloride. A similar effect is manifested by glutaryl
chloride and is absent for adipinyl chloride.
10. W. Borsche, Liebigs Ann., 1936, 526, 1.
11. W. S. Johnson, A. Goldman, J. Am. Chem. Soc., 1945, 67, 430.
12. Ya. L. Gol´dfarb, A. P. Yakubov, L. I. Belen´kii, Zh. Org.
Khim., 1970, 6, 2518 [Russ. J. Org. Chem. (Engl. Transl.)
1970, No. 7].
13. V. Z. Shirinyan, N. V. Kosterina, A. V. Kolotaev, L. I. Belen´ꢀ
kii, M. M. Krayushkin, Chem. Heterocycl. Compd. (Engl. Transl.)
2000, 36, 219 [Khim. Geterotsikl. Soedin., 2000, 261].
14. L. I. Belen´kii, V. Z. Shirinyan, G. P. Gromova, A. V. Koloꢀ
taev, Yu. A. Strelenko, S. N. Tandura, A. N. Shumskii, M. M.
Krayushkin, Chem. Heterocycl. Compd. (Engl. Transl.) 2003,
39, 1570 [Khim. Geterotsikl. Soedin., 2003, 1785].
15. M. M. Krayushkin, V. Z. Shirinyan, L. I. Belen´kii, A. Yu.
Shadronov, L. G. Vorontsova, Z. A. Starikova, Russ. Chem.
Bull. (Int. Ed.), 2002, 51, 1510 [Izv. Akad. Nauk, Ser. Khim.,
2002, 1392].
16. M. M. Krayushkin, V. Z. Shirinyan, L. I. Belen´kii, A. Yu.
Shadronov, Russ. Chem. Bull. (Int. Ed.), 2002, 51, 1515 [Izv.
Akad. Nauk, Ser. Khim., 2002, 1396].
17. P. Cagniant, D. Cagniant, Bull. Soc. Chim. France, 1955, 680.
18. D. C. Owsley, J. M. Nelke, J. J. Bloomfield, J. Org. Chem.,
1973, 38, 901.
Calculation and Experimental Procedures
Quantum chemical calculations in the semiempirical PM6 apꢀ
proximation were performed using the published program.25 The
DFT calculations were performed by the B3LYP/6ꢀ311+G(2d,p)
method using the GAUSSIANꢀ09 program package.26
Acylation of thiophene with glutaryl dichloride. A solution of
glutaryl dichloride (18.5 g, 0.11 mol) in benzene (50 mL) was
added dropwise within 2 h at 0—3 С to a solution of thiophene
(15 g, 0.18 mol) and SnCl4 (46 g, 22 mL, 0.18 mol) in benzene
(200 mL). Then the mixture was treated with hydrochloric acid
(1 : 10) at 10 С and washed with a solution of Na2CO3 and
water. Benzene was distilled off. The residue was recrystallized from
butyl acetate. 1,5ꢀDi(2ꢀthienyl)pentaneꢀ1,5ꢀdione was obtained
in a yield of 1.2 g (5.3%), m.p. 88—89 С (cf. Ref. 17: m.p. 88.5 С).
The acidification of the alkaline extract gave 5 g (27% yield) of
5ꢀoxoꢀ5ꢀ(2ꢀthienyl)valeric acid, m.p. (cf. Ref. 17: m.p. 92 С).
19. K. Takahashi, M. Matsuzaki, K. Ogura, H. Iida, J. Org.
Chem., 1983, 48, 1909.
20. D. Mousset, I. Gillaizeau, A. Sabatie, P. Bouyssou, G. Coudꢀ
ert, J. Org. Chem., 2006, 71, 5993.
21. L. N. Lucas, J. van Esch, R. M. Kellogg, B. L. Feringa,
Chem. Commun., 1998, 2313.
22. L. N. Lucas, J. van Esch, R. M. Kellogg, B. L. Feringa, Eur.
J. Org. Chem., 2003, 155.
23. S. Z. Taits, Ya. L. Gol´dfarb, Izv. Akad. Nauk SSSR, Ser.
Khim. 1963, 1289 [Bull. Acad. Sci. USSR, Div. Chem. Sci.
(Engl. Transl.), 1963, 12].
24. J. H. Billmann, F. N. Travis, Proc. Indiana Acad. Sci., 1945,
54, 101; Chem. Abstr., 1946, 40,18262.
References
25. J. J. P. Stewart, J. Mol. Model., 2007, 13, 1173.
26. M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fuꢀ
kuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E.
Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand,
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar,
J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E.
Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo,
R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin,
R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Moroꢀ
kuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Danꢀ
nenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J. B. Foresꢀ
man, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, Rev.
A.02 SMP, Gaussian, Inc., Wallingford CT, 2009.
1. G. G. Abashev, A. Yu. Bushueva, E. V. Shklyaeva, Chem.
Heterocycl. Compd. (Engl. Transl.), 2011, 47, 130 [Khim.
Geterotsikl. Soedin., 2011, 167].
2. W. Horton, J. Org. Chem., 1949, 14, 761.
3. A. Merz, F. Ellinger, Synthesis, 1991, 462.
4. P. E. Just, K. I. ChaheꢀChing, P. C. Lacaze, Tetrahedron,
2002, 58, 3467.
5. V. I. Smirnov, A. V. Afanas´ev, L. I. Belen´kii, Chem. Heteroꢀ
cycl. Compd. (Engl. Transl.), 2010, 46, 1199 [Khim. Geterotsikl.
Soedin., 2010, 1485].
6. V. I. Smirnov, A. V. Afanas´ev, I. S. Prostakishin, L. I.
Belen´kii, Tez. dokl. II Vseross. konf. "Uspekhi sinteza i komꢀ
pleksoobrazovaniya," chast´ 1, sektsiya "Organicheskaya khiꢀ
miya" [Proc. II AllꢀRussia Conf. "Progress in Synthesis and
Complex Formation," Part 1, Section "Organic Chemistry"]
(April 23—27, 2012), p. 76 (in Russian).
7. F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G.
Orpen, R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987,
No. 12, Supplement, S1.
Received November 20, 2012