GaCl3-Mediated "inverted" Formal [3 + 2]-Cycloaddition of Donor-Acceptor Cyclopropanes to Allylic Systems

Article abstract of DOI:10.1021/acs.joc.8b00959

A new process of "inverted" formal [3 + 2]-cycloaddition of donor-acceptor cyclopropanes (DACs) to allylic systems to give polyfunctionalized cyclopentanes has been developed. Unlike the classical version of formal [3 + 2]-cycloaddition, a DAC acts in thi

Full text of DOI:10.1021/acs.joc.8b00959

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Article
GaCl3–Mediated “Inverted” Formal [3+2]-Cycloaddition
of Donor–Acceptor Cyclopropanes to Allylic Systems
Maria A. Zotova, Roman A. Novikov, Evgeny V. Shulishov, and Yury V. Tomilov
J. Org. Chem., Just Accepted Manuscript • Publication Date (Web): 02 Jul 2018
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GaCl3–Mediated “Inverted” Formal [3+2]-Cycloaddition of Donor–
Acceptor Cyclopropanes to Allylic Systems
Maria A. Zotova,§ Roman A. Novikov,*,§ Evgeny V. Shulishov, and Yury V. Tomilov*
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N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991
Moscow, Russian Federation
ABSTRACT: A new process of “inverted” formal [3+2]-cycloaddition of donor-acceptor cyclopropanes
(DACs) to allylic systems to give polyfunctionalized cyclopentanes has been developed. Unlike the classical
version of formal [3+2]-cycloaddition, a DAC acts in this process as a two-carbon synthon (1,2-zwitterionic
reactivity type), while an alkene acts as a three-carbon synthon. Tetramethylethylene, allylbenzenes,
homoallylbenzene, terminal and internal aliphatic alkenes, and methylenecyclobutane were successfully used
as alkenes. Furthermore, in order to suppress annulation at the aromatic ring in 2-arylcyclopropane-1,1-
dicarboxylates and enhance the selectivity of the reaction with the allylic system of alkenes, we suggested a
new approach for managing the reactivity of DACs involving substitution at both ortho positions of the
aromatic ring. Multinuclear NMR spectroscopy was used to study the structure of the 1,2-zwitterionic gallium
complexes generated and their properties, and to examine the mechanisms of the occurring reactions.
INTRODUCTION
multiple bonds,7,9,10 including DAC 1 dimerization
processes,7,8 is the most general process. The reaction of
formal 1,2-zwitterions with aromatic aldehydes that
occurs as [3+2]-annulation, as well as more complex
cascade processes,11 is yet another general process. Apart
from these reactions, a number of other narrower types of
processes specific of certain substrate combinations have
been developed and reported.10b,12,13 It should be noted
that formal [2+2]-cycloaddition of gallium 1,2-
zwitterionic complexes to alkenes to give cyclobutanes
was never implemented. Clearly, the 1,2-zwitterionic type
of DAC reactivity is yet a very young chapter in the
chemistry of cyclopropanes.
Donor-acceptor cyclopropanes (DACs)1 proved
themselves as unique building blocks in organic
synthesis,2 mainly as sources for generation of 1,3-
zwitterions. 2-Arylcyclopropane-1,1-dicarboxylates 1 are
popular DACs3 that are also used in this study. This field
of chemistry currently continues to develop rapidly4,5 and
opens up new unique pathways of DAC reactivity,6 thus
rising the prospects of this class of compounds in organic
chemistry. One of the new key types of DAC 1 reactivity
involves the method for generation of formal 1,2-
zwitterions 2 from them in the presence of gallium
compounds (Scheme 1) developed in our scientific
group.7,8 The 1,2-zwitterionic path of reactivity is of
general nature and can be implemented with various
substrates.7–12 It opens access to an extensive class of
unique processes that allow various carbo- and
heterocyclic structures to be constructed, and it continues
to be developed rapidly.10b,12
Taking the above into consideration, in this work we
continued a detailed study of the reactivity of formal 1,2-
zwitterions generated from DACs in the presence of
gallium compounds, with focus on substrates with
multiple C–C bonds. It should be noted that reactions of
DACs with alkenes have been studied pretty well by
now.9,14,15 The formal [3+2]-cycloaddition (Scheme 2),14
in which DACs serve as sources of 1,3-zwitterionic
intermediates, have been studied most thoroughly.
Moreover, the [3+2]-annulation (Scheme 2)15 and the
The reaction pathway considerably depends on the
substrate which reacts with the formal 1,2-zwitterion 2
generated (Scheme 1). [4+2]-Annulation at the aromatic
ring that occurs with various substrates containing
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aforementioned [4+2]-annulation (Scheme 1) are also
In this work we succeeded in implementing one more
well known.9
rather general pathway of DAC 1 reactions with alkenes
and suggested methods for controlling the DAC
reactivity. The method that we developed is an example
of “inverted” formal [3+2]-cycloaddition of DACs to
alkenes (Scheme 1). Unlike the classical variant, a DAC
serves as a two-carbon building block in this process,
while an alkene serves as a three-carbon block (i.e., as an
allylic system). It should be noted that in the literature the
single example of similar process is known, realized by
Scheme 1. 1,2-Zwitterionic reactivity of DACs and its
reactions with different substrates.
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Snider’s
group
(1986).14e
Reaction
of
cyclopropanedicarboxylate with methylenecyclohexane in
the presence of EtAlCl2 (2 equiv.) leads to the formation
of product of formal [3+2]-cycloaddition (Scheme 3).
RESULTS AND DISCUSSION
The first group of “inverted” formal [3+2]-
cycloaddition
processes
was
developed
for
tetramethylethylene 3 (TME). In this case, DACs were
used as sources for generation of gallium 1,2-zwitterionic
intermediates 2 in the presence of anhydrous gallium
trichloride.
We
used
2-phenylcyclopropane-1,1-
dicarboxylate 1a as the model DAC. It should be noted
that TME markedly differs in reactivity from the majority
of alkenes and quite poorly undergoes [4+2]-annulation
typical of these compounds.9 In this case, resinification
and oligomerization were the main reaction pathways,
which required an optimization of the reaction conditions
in order to minimize these processes (Table 1).
Scheme 2. Known reactions of DACs with alkenes to
form five-member cycle.
Table 1. Optimization of reaction conditions for
reaction 1a with tetramethylethylene (TME). a
Entry
Concentration TME, 3
of 1a
T
4a
Yield (%)
(equiv.) b (oC)
(mM)
1
2
3
4
5
6
7
8
286
286
133
133
133
66
3
3
1
3
5
1
3
5
20
40
40
40
40
40
40
40
23 c
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Scheme 3. Known example of formal [3+2]-
cycloaddition of cyclopropanedicarboxylate to
methylenecyclohexane.
<5 c
57
10 c
5 c
66
67
66
16 c
a
b
As a result, DACs are widely used as convenient
precursors to assemble functionally substituted five-
membered carbocycles.16 As the cyclopentane skeleton is
widespread in many synthetic and natural biologically
active compounds,17 such as prostaglandins, steroids,
terpenoids etc., various methods to assemble the
cyclopentane skeleton are developed and new variants are
searched for.
1 mmol of DAC 1a in dry CH2Cl2 was used. TME 3 was
added in 1 mL dry CH2Cl2. c NMR yields.
As a result, we succeeded in finding conditions that
gave cyclopentane-1,1-dicarboxylate 4a in 67% yield
(Table 1, Entry 7). The reaction involved one TME
methyl group. This process was found to be quite
sensitive to the reaction conditions (the optimum
conditions being 40 °C, 2 h). The decrease of temperature
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entails a lowering in the yield of the target products due to
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9
4-ClC6H4 (c)
1.1
0
0
5
15
90
60
4c, 40 (1/1.35)
4d, 41 (1.1/1)
4e, 35 (1/1.1)
4f, 24 (1.5/1)
4g, 31 (1.5/1)
4h, 60 (1/1)
the insufficiency of activation of starting substrates (Table
1, Entry 1). Herewith, the reaction time plays no
significant role, as well as a slight increase in the amount
of GaCl3. The process is also very sensitive to the amount
of TME used. The maximum yields of cyclopentane 4a
were obtained using 3 equiv. of TME, whereas deviations
from this excess in any direction decreased the target
product yields significantly (Table 1, Entries 3–5 and 6–
8). Thus, a deficiency of TME leads to a significant
dimerization of the cyclopropane 1a, while a large excess
of TME — to a significant oligomerization and
resinification, and also to adducts of poly-addition of
TME. It was also found that, to suppress oligomerization
processes, the reaction had to be performed under
sufficiently strong dilution.
3-BrC6H4 (d) 1.3
2-ClC6H4 (e)
1.3
4-NO2C6H4 (f) 1.5
3-NO2C6H4 (g) 1.3
2,6-F2C6H3 (h) 1.3
2,6-Cl2C6H3 (i) 1.5
25 90
25 90
25 45
40 75
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4i, 82 (2/1)
a
General conditions: 1 mmol of 1a–i in 15 mL dry CH2Cl2
b
c
was used. TME 3 was added in 1 mL dry CH2Cl2. The
reaction conditions are given for the first stage (formation of
2); conversions for the formal 1,2-zwitterions 2a–i and their
yields are more then 80-90% by NMR.
chromatography on silica gel. Diast. ratio for isolated
compounds.
d
Yields after
e
Further, we studied the scope of the reaction for
various DACs and tetramethylethylene under optimized
conditions (Table 2). Arylcyclopropanedicarboxylates
1b–i containing substituents at various positions of the
aromatic ring were studied as the DACs. The process was
carried out in two stages: at first, cyclopropane 1 was
converted to the corresponding formal 1,2-zwitterion 2 in
the presence of GaCl3, then the zwitterion was entered
into the reaction with a threefold excess of TME
performed for 2 h at 40 °C. The reaction gave a series of
substituted cyclopentanes 4a–i as a mixture of two
Cyclopentanes 4 themselves are formed as two
diastereomers with a slight predomination of trans-
isomers in most cases. The configurations of these two
diastereomers were confirmed by NOESY spectra (Fig.
1).
diastereomers
that
were
easily
isolated
by
chromatography on silica gel (without separation from
each other in most cases) (Table 2). On the whole, the
products were formed in quite moderate yields. The best
Figure 1. NOE data for the stereochemistry analysis of
cyclopentanes 4.
results were observed in the case of ortho,ortho-
18
disubstituted DACs 1h,i
especially with
(Table 2, Entries 8 and 9),
It should be noted that cyclopropanes 1g–i are new
compounds19 and cyclopropane 1f was never used in 1,2-
zwitterionic processes. Therefore, the conditions for
generation of the corresponding 1,2-zwitterionic gallium
complexes 2f–i
2,6-dichlorophenylcyclopropane-
dicarboxylate 1i. The introduction of 2 halogen atoms in
both ortho-positions allows to suppress the processes of
electrophilic substitution in the aromatic ring as well as
the oligomerization process, and thereby to increase the
yield of the target products.
7–10
from these compounds were studied
first of all (Table 2, Entries 6–9). The completeness of the
starting DACs conversion was determined by NMR
spectroscopy of the reaction mixture and by its treatment
with excess methanol. This treatment converted gallium
complexes
arylethylidenemalonates whose content could be
measured easily.8 Formal 1,2-zwitterions
were
generated most readily in the case of 1a and para-halo-
substituted arylcyclopropanedicarboxylates (0–5°C, 10–
15 min, 1.1 equiv. GaCl3) (Table 2, Entries 2 and 3).9 The
reaction time had to be increased to 60–90 min for meta-
and ortho-substituted compounds in combination with a
slightly larger amount of GaCl3 (Table 2, Entries 4 and
5).9 Nitro- and 2,6-disubstituted DACs 1f–i proved to be
the least reactive and their reactions had to be performed
at 25°C or higher and using excess GaCl3 (Table 2,
Entries 6–9).
Table 2. Scope of the formal [3+2]-cycloaddition of
tetramethylethylene to DACs. a,b
2
to
the
corresponding
2
The structure of the resulting cyclopentanes 4 is very
interesting, and the process apparently occurs not just as
addition of a gallium 1,2-zwitterionic intermediate to
TME 3. Apparently, the double bond in TME is sterically
hindered due to the steric effect of the methyl groups and
addition to it occurs very slowly. The TME isomerization
into 2,3-dimethylbut-1-ene (5), in which the double bond
Entry Ar
Reaction conditions c Product,
Yield (%) d
GaCl3
T
t
and (trans/cis) e
(equiv.) (oC) (min)
1
2
Ph (a)
4-FC6H4 (b)
1.1
1.1
0–5 10
15
4a, 67 (1.15/1)
4b, 39 (1.2/1)
0
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becomes a terminal one that is much more reactive,
fact, it was found that incorporation of one phenyl group
occurs much faster. Formal 1,2-zwitterion 2 adds to this
bond to give products 4. In this case, alkene 5 acts as an
allylic system (a detailed description of the reaction
mechanism is provided below).
is insufficient for stabilizing the required carbocation IV
in order to make the process involve only this
carbocation. In fact, cyclization occurs even before
hydride shift, and in this case a well-known [4+2]-
annulation at the aromatic ring of the starting
cyclopropane 1a occurs to give compound 7.9 This
process does not occur in the case of TME, apparently
due to the steric factor of the methyl groups that makes
cyclization on the aromatic ring unfavorable. The
formation of the target cyclopentane 8 was not observed,
either, if the temperature was varied from 20 to –78 °C.
3
4
5
6
7
8
9
This assumption was successfully confirmed by
monitoring the reaction in an NMR spectrometer. In fact,
formation of isomeric alkene 5 was detected upon
addition of GaCl3 to a solution of tetramethylethylene in
CD2Cl2 (Scheme 4). It is present in the reaction mixture in
a small steady-state concentration and is consumed at
once in the subsequent reactions until the starting TME is
exhausted. In the absence of the substrate, alkene 5 is
quickly polymerized under the action of GaCl3. If formal
1,2-zwitterion 2a is added to the resulting alkene 5 in the
absence of TME in the mixture, product 4a is formed,
though in small amounts.
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Since electrophilic cyclization at the aromatic ring
strongly hinders “inverted” formal [3+2]-cycloaddition, a
radical method to prevent it was suggested. It involves the
substitution of both ortho positions of the aromatic ring in
the starting cyclopropanes 1, which prevents electrophilic
attack at this position. To do so, we used the previously
Scheme 4. GaCl3-Mediated isomerization of TME
during the reaction.
18
synthesized cyclopropanes 1h–j
containing fluorine,
chlorine atoms or methyl-groups at both ortho positions.
This approach proved itself well in the reaction of 1h,i
with TME described above: the
yield of
cyclopentanedicarboxylate 4i was the highest in the case
of cyclopropane 1i (Table 2).
Scheme 6. Reactions of DAC 1a with allylbenzene.
To preserve the pathway of “inverted” formal [3+2]-
cycloaddition of DACs on transition to other alkenes, one
of the key features of this process should be considered.
An important stage that enables cyclization into
cyclopentane 4 involves carbocation rearrangement in
intermediate I formed upon addition of activated DAC to
alkene 5. In this case, stabilization of intermediate II that
is formed is not inferior to that of intermediate I (Scheme
5). Cyclization preferentially occurs in intermediate II,
since a much more stable five-membered ring is formed
in this case, instead of a four-membered one in the case of
intermediate I.
Since preliminary generation of gallium 1,2-
zwitterionic intermediates 2 is used in this process, it
appeared interesting and important to study their
properties. The formal 1,2-zwitterions 2h–j generated
(Scheme 7) were found to be much more stable than the
Scheme 5. General concept to «inverted» formal [3+2]-
cycloaddition.
8
parent intermediate 2a and could exist for more than 1
day at room temp. in solutions without appreciable
degradation (however, we failed to isolate them from
solutions). Also, the same gallium complexes 2h–j could
be generated from the preliminary obtained corresponding
alkylidenemalonates with GaCl3 (Scheme 7).
Scheme 7. The conditions for the formation of gallium
complexes 2h–j.
Thus, to implement the required “inverted” formal
[3+2]-cycloaddition, one should create conditions for
hydride shift in the alkene, e.g., introduce stabilizing
electron-donating groups to the allyl position required to
stabilize the carbocation (intermediate III, IV) (Scheme
5). For example, allylbenzene 6a is one of the simplest
substrates that satisfies this requirement.
A study of the reaction of allylbenzene 6a with
cyclopropanedicarboxylate 1a under conditions of formal
1,2-zwitterion 2a generation showed that the suggested
concept is insufficient to change the pathway of reactions
of formal 1,2-zwitterions with alkenes (Scheme 6). In
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signals of 2a.8 Apparently, a considerable contribution to
structures 2h,i is made by the weak intramolecular
coordination of the halogen atom to the carbocationic
center. This explains the difference in the chemical shifts
and the higher stability of complex 2h,i in comparison
with 2a.
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The structures of these 1,2-zwitterionic gallium
complexes 2h–j in solutions were studied by multinuclear
NMR spectroscopy. Figure 2 demonstrates some spectral
data for 2,6-difluoro-substituted complex 2h as an
example. Gallium complexes 2h–j exist in CD2Cl2
solution predominantly in a dimeric form due to the
formation of two Ga–Cl–Ga bridges (Scheme 8).8
Formation of the dimeric structures was investigated
using 2D Diffusion Ordered NMR Spectroscopy (DOSY),
which allows to estimate a molecular weight of
compounds in solution without its isolation (Scheme 8;
also see Supp.Inf.).8
Scheme 8. Formation of the dimeric structures for
complexes 2h–j, and 2D DOSY spectrum for 2i
demonstrating this.
Figure 2. NMR data for the formal Ga-1,2-zwitterion
2h.
Since the 1,2-zwitterionic structure is a strongly
polarized
form
of
the
corresponding
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arylethylidenemalonate, the chemical shifts of the CH +
moiety in the H and 13C NMR spectra are the most
1
characteristic parameters for the description of this
structure. In this case, the CH + moiety has the strongest
downfield shifts in the spectra. In the 13C NMR spectra
they manifest themselves in weaker field in comparison
with the signals of ester groups, which indicates a
considerable polarization of the C=C bond in complexes
2. However, in comparison with complex 2a,7a the shifts
of the CH+ moiety for 2h,i were found to be considerably
Figure 3. Key chemical shifts in NMR spectra for the
formal Ga-1,2-zwitterions 2h–j (for dimeric forms).
1
shifted upfield (by 0.33 and 0.39 ppm in the H spectra,
Incorporation of substituents to the ortho positions of
the benzene ring was found to be a good solution for
changing the pathway of the reaction with allylbenzene
that enabled the target “inverted” formal [3+2]-
and by 7.7 and 6.6 ppm in the 13C NMR spectra) (Fig. 2
and 3). The 71Ga and 19F signals of 2h also manifest
upfield shifts in comparison with the corresponding
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cycloaddition. This process was studied using dichloro
nonexistent. Aggravation of the reaction conditions only
derivative 1i under conditions of formal 1,2-zwitterion 2i
generation and a series of substituted allylbenzenes 6a–e
to give a set of the corresponding formal [3+2]-
cycloaddition products 9 (Table 3). However, in addition
to the formation of the target cyclopentanes 9, yet another
competing reaction occurs that gives acyclic isomeric
compounds 10. In this case, the degree of cyclization
depends on substituents used at the aromatic ring of the
starting allylbenzenes (Table 3, Entries 1–5). However,
the yields of cyclopentanes 9 and acyclic compounds 10
change non-systematically. Only cyclopentane 9c is
formed from meta-allyltoluene 6c (Table 3, Entry 3),
whereas only compound 10e is formed from ortho-
allylbromobenzene 6e (Table 3, Entry 5).
resulted in degradation of these compounds. So, the
variation of temperature, reaction time, excess of
allylbenzene, and also the amount of GaCl3 did not
provide a positive result.
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Figure 4. NOE data for the stereochemistry analysis of
cyclopentanes 9.
Table 3. Scope of the reactions of 1i with alkenes in the
presence of GaCl3. a
Apart from allylbenzenes, homoallylbenzene 6f and
terminal alkenes 6g–i also enter the reaction with
zwitterion 2i (Table 3, Entry 6). It is interesting to note
that only acyclic compound 10f is formed in the case of
homoallylbenzene 6f. In the case of aliphatic alkenes 6g–
i, the content of cyclic compounds 9g–i markedly
increases with an increase in the alkyl chain length from
pent-1-ene to hept-1-ene (Table 3, Entries 7–9).
Furthermore, the reaction with these alkenes also gives
isomeric acyclic compounds 11–13 as side products (Fig.
5) whose content strongly decreases as the alkyl chain in
the starting alkene grows. In fact, the overall amount of
compounds 11g–13g formed in the case of pent-1-ene is
comparable to that of the main products (~21%), while in
the case of hept-1-ene, only minor amounts of compounds
11i–13i are formed (~6%). An increase in the alkyl chain
length leads to greater stability of the intermediate
carbocations, which allows them to exist a longer time
which necessary for the cyclization into cyclopentane,
rather than not immediately split off the proton with
formation of the acyclic structures.
Entry Alke-
ne b
R
Comp. Yield (%) c Comp. Yield
9
(trans/cis) d 10
36 (1.5/1) 10a
(%) c
21
1
2
3
4
5
6
7
8
9
6a
6b
6c
6d
6e
6f
Ph
9a
4-FC6H4 9b
3-MeC6H4 9c
2-MeC6H4 9d
2-BrC6H4 9e
32 (1.7/1) 10b
40
20 (2/1)
10c
0
15 (3.5/1) 10d
25
0
0
10e
10f
47
CH2Ph
Et
9f
9g
9h
9i
50
6g
6h
6i
10 (~1/1) e 10g
20 (1.1/1) 10h
32 (1.5/1) 10i
24 f
21 f
21 f
n-Pr
n-Bu
Figure 5. Side products obtaining in reactions of Ga-
complex 2i with alkenes 6g–j.
a General conditions: 1 mmol of 1i in 15 mL dry CH2Cl2 was
b
used. Alkenes 6a–i (3 mmol) were added in 2 mL dry
c
d
CH2Cl2. Yields after chromatography on silica gel. Diast.
ratio for isolated compounds. e NMR yield. f Compounds 11–
13 have also formed as by-products.
DACs with other aryl substituents were also
investigated in the reaction with allylbenzene (Scheme 9).
2,6-Difluoro-DAC 1h reacts similarly to 1i and quite
successful gives the corresponding cyclopentane product
9j with a moderate yield. Cyclopropane 1j with two
methyl-groups in both ortho-positions is inactive,
apparently due to the significant steric hindrance created
by methyl groups.
This result is apparently affected by rather a fine
combination of electronic and steric factors. Also, some
of products may be low stable in the presence of gallium
compounds and partially decompose during isolation. The
yields of reaction products are rather poor in all the cases,
even at high dilutions. Cyclopentanes 9 themselves are
formed as two diastereomers with predomination of trans-
isomers. The configurations of these two diastereomers
were confirmed by NOESY spectra (Fig. 4). Control
experiments showed that transitions between compounds
9 and 10 under the effect of GaCl3 were completely
Introduction of electron-withdrawing substituents into
Ph-ring in DAC also allows to suppress the annulation
processes and to direct the process on the path of the
“inverted” formal [3+2]-cycloaddition. This is another
approach instead of the replacement of both ortho-
positions in the Ph-ring. We demonstrated it using 3-NO2-
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DAC 1g (Scheme 9). In this case, the yield of the product
is quite lower, due to a significant implementation of
oligomerization processes of the NO2-containing
substrates in the presence of Ga-compounds.
3
4
5
6
7
8
Scheme 9. Reactions of ortho,ortho-difluoro- and meta-
nitro-DACs with allylbenzene.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
When one considers the possible mechanisms of the
reactions observed, the key role of gallium trichloride
should be taken into account as it performs several
functions at once. In the case of DACs 1 its functions are
the opening of the three-membered ring and generation of
gallium 1,2-zwitterionic intermediate 2.7–10 In the
presence of GaCl3, tetramethylethylene 3 is isomerized to
terminal 2,3-dimethylbut-1-ene, which reacts with
intermediate 2. The same occurs with internal hex-3-ene.
Generation of required intermediates is followed by attack
of the 1,2-zwitterionic gallium complex 2 at the terminal
double bond of 1-alkenes to give intermediate V.
Cyclization of the latter on the malonyl moiety is
unfavorable since it would result in a four-membered
ring. In turn, electrophilic attack with cyclization on the
aromatic moiety is blocked either by steric factors or by
substitution of positions accessible for attack in the
starting cyclopropane 1 with halogens (Scheme 12).
It is interesting that the reaction of hept-3-ene 6j with
cyclopropane 1i gave the same products as with isomeric
hept-1-ene 6g and the yields were almost the same
(Scheme 10). It is likely that hept-3-ene is first isomerized
during the reaction in the presence of GaCl3 to give hept-
1-ene (the double bond “jumps” over 2 carbon atoms),
which then reacts with Ga-complex 2i. This fact was
confirmed by NMR experiments for the mixtures of hept-
3-ene with GaCl3 in CD2Cl2 in NMR tube (Scheme 10). In
this case, the internal double bond in hept-3-ene is much
less reactive (then the terminal in hept-1-ene) and the
reaction does not involve it.
Scheme 10. Reaction with hept-3-ene.
Scheme 12. General proposed mechanism for the
addition of DACs to allylic systems.
An interesting result was obtained in the reaction of
methylenecyclobutane 6k with 1i under conditions of
formal 1,2-zwitterion 2i generation. This process also
occurs as “inverted” formal [3+2]-cycloaddition but it
also involves cyclobutane ring opening. As a result, a
mixture of two isomeric cyclopentenes 14a,b is formed in
49% total yield, which is quite good, considering the high
reactivity of methylenecyclobutane (Scheme 11).
Scheme 11. Reaction with methylenecyclobutane.
Subsequently, carbocation V undergoes conversion by
two main pathways. Both involve successive carbocation
rearrangement along the carbon chain, but in opposite
directions. “Inverted” formal [3+2]-cycloaddition occurs
upon hydride shift towards generation of intermediate VI,
which then undergoes cyclization to give a five-
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membered ring (compound 9). To make it
a
predominating process, R1- and R2-substituents should be
introduced into the structure of the starting alkene in order
to stabilize the positive charge in the required position.
approach for changing the reaction pathway has been
demonstrated.
EXPERIMANTAL SECTION
5
General Experimental Details. All reagents and solvents
used were commercial grade chemicals without additional
purification. All operations with GaCl3 were carried out
under a dry argon atmosphere. TLC analysis was performed
on Silufol chromatographic plates. For preparative
chromatography, silica gel 60 (0.040−0.063 mm) was used.
1H and 13C{1H} NMR spectra were recorded on 400 MHz
(400.1 and 100.6 MHz, respectively) and 300 MHz (300.1
and 75.5 MHz, respectively) spectrometers in CDCl3
containing 0.05% Me4Si as the internal standard.
Determinations of the structures and stereochemistry of the
obtained compounds and assignments of the 1H and 13C
signals were made with the aid of 1D and 2D DEPT, JMOD,
COSY, TOCSY, NOESY, HSQC, and HMBC spectra. 19F
NMR spectra were recorded on a 300 MHz spectrometer
(282.4 MHz; standard CFCl3). Determinations of the
structures and assignments of the 19F signals were made with
the aid of 2D 1H,19F HMQC, and HMBC spectra. Monitoring
of the reactions in an NMR tube was done in a CD2Cl2
solution containing 0.05% Me4Si as the internal standard. IR
spectra were obtained on an FT-IR spectrometer in CHCl3
solution (1%). Mass spectra were recorded using electron
impact ionization (EI; 70 eV, direct inlet probe). High-
resolution mass spectra (HRMS TOF) were obtained using
simultaneous electrospray ionization (ESI). The elemental
6
7
8
9
Scheme 13. Proposed mechanism for the addition to
methylenecyclobutane.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The second pathway that results in acyclic products 10
implies hydride shift towards the malonyl moiety and
requires two successive rearrangements via intermediate
VII. The stable intermediate VIII, which is an analogue
of zwitterions 2, is formed eventually. After
compositions were determined on
instrument.
a
CHN analysis
Synthesis of Starting Cyclopropanes 1a−j. Starting
cyclopropanes 1a−j (ACDC) were synthesized from the
corresponding aromatic aldehydes through
a standard
decomposition
of
the
reaction
mixture
and
synthetic sequence of Knoevenagel/Corey−Chaykovsky
decomplexation of GaCl3, this intermediate gives the final
compound 10. It should be noted that this pathway is not
observed for TME, apparently due to the easier hydride
shift to give intermediate VI. In the case of aliphatic
terminal alkenes, intermediates V–VII can, in addition to
the predominant processes, “irreversibly” abstract a
proton to form double bonds and give minor compounds
11–13.
reactions.18
General procedure for the synthesis of cyclopropanes
1g–j. Aldehyde (2.0 g, 17.9 mmol) and dimethyl malonate
(2.36 g, 17.9 mmol) were refluxed in benzene (5 mL) in the
presence of piperidine (0.07 mL, 0.7 mmol) and acetic acid
(0.2 mL, 3.6 mmol) for 4 h yielding the crude product, which
used without additional purification. To a stirred suspension
of NaH (0.24 g, 6 mmol) in dry DMSO (10 mL)
trimethylsulfoxonium iodide (1.32 g, 6 mmol) was added in
As one can see, both products 9 and 10 are located far
from each other on the reaction pathways. And, though all
reactions involving carbocations are potentially
reversible, isomerization of VIII to VI (and hence
cyclization to give 9) is impossible in reality, especially
since carbocation VIII is quite stable.
a
single portion under argon atmosphere at room
temperature. Vigorous evolution of hydrogen lasted ca. 10
min, after which the reaction mixture was stirred for
additional 25 min. Then a solution of alkylidenemalonate (5
mmol) in dry DMSO (2 mL) was added in a single portion.
The resulted mixture was stirred under conditions specified,
poured into H2O-ice (10 mL) and extracted with diethyl ether
(5  5 mL). The combined organic layers were washed with
water (5  5 mL), dried with Na2SO4 and evaporated. Pure
product was obtained after column chromatography on silica
gel.
In conclusion, we have developed a new process of
“inverted”
formal
[3+2]-cycloaddition
of
2-
arylcyclopropanedicarboxylates to allylic systems in the
presence of GaCl3, where the former act as two-carbon
synthons and the alkenes as a three-carbon ones. The
reaction occurs with rather a broad range of substrates to
give polyfunctionalized cyclopentanes, as well as acyclic
Dimethyl
2-(3-nitrophenyl)cyclopropane-1,1-
~

products.
Tetramethylethylene,
allylbenzenes,
dicarboxylate (1g). Yellow solid. Yield 50%. IR (CHCl3):
3053, 3024, 3015, 2955, 1728 br (C=O), 1533 (NO2), 1438,
1352 (NO2) cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C13H13NO6Na 302.0635; Found 302.0633. 1H NMR
(300.1 MHz, CDCl3) δ 3.03 (dd, 1H, (H(2)), 2J = 9.2 Hz, 3J =
5.5 Hz), 2.24 (dd, 1H, (H(2)), 2J = 7.9 Hz, 3J = 5.5 Hz), 3.30
(t, 1H, (H(3)), J = J = 8.5 Hz), 3.43 and 3.82 (both s, 2 ×
3H, 2 OMe), 7.37–7.64 and 8.09–8.31 (both m, 2 × 2H,
C6H4) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 19.1 (C(2)),
homoallylbenzene, terminal and internal aliphatic alkenes,
and methylenecyclobutane can be used as the alkenes. In
addition, we suggested a new approach to control the
reactivity of DACs 1 in order to enhance the selectivity of
the target process, which involves the substitution of both
ortho-positions in the aromatic ring for suppressing the
annulation side processes. The efficiency of the suggested
2
3
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~
31.3 (C(1)), 37.2 (C(3)), 52.5 and 53.0 (2 OMe), 122.5
(CH(4´)), 123.5 (CH(2´)), 129.2 (CH(5´)) , 134.7 (CH(6´)),
139.8 (C(1´)), 148.1 (C(3´)), 165.5 and 169.5 (2 COO) ppm.

thick oil. IR (CHCl3): 3043, 3021, 3012, 2954, 1721 br
(C=O), 1455, 1434, 1269, 1233, 1188 cm–1. HRMS (ESI-
TOF) m/z: [M + Na]+ Calcd for C19H26O4Na 341.1723;
1
Dimethyl
2-(2,6-difluorophenyl)cyclopropane-1,1-
Found 341.1720. Isomer trans-4a. H NMR (400.1 MHz,
CDCl3) δ 0.72 and 1.17 (both s, 2 × 3H, 2 Me at C(2)), 0.79
(d, 3H, Me at C(3), J = 7.1 Hz), 1.26–1.34 and 1.69–1.78
~
dicarboxylate (1h). Yellowish oil. Yield 50%. IR (CHCl3): 
3048, 3031, 3014, 2954, 1725 br (C=O), 1560, 1437, 1330,
1290, 1241, 1188 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+
Calcd for C13H12F2O4Na 293.0596; Found 293.0601. 1H
3
(both m, 2 × 1H, H2C(4)), 2.05 (t, 1H, Ha, 2J = 3J = 12.3 Hz),
2.65–2.79 (m, 1H, (H(3)), 2.95–3.06 (m, 1H, (H(5)), 3.08
(dd, 1H, Hb, 2J = 12.2 Hz, 3J = 2.6 Hz), 3.74 and 3.80 (both s,
2 × 3H, 2 OMe), 7.14–7.30 (m, 5H, Ph) ppm. 13C{1H} NMR
(100.6 MHz, CDCl3) δ 14.7 (Me at C(3)), 19.8 and 22.5 (2
Me at C(2)), 36.0 (C(4)), 39.0 (CH2), 40.5 (C(3)), 44.8
(C(5)), 48.4 (C(2)), 51.6 and 52.0 (2 OMe), 72.2 (C(1)),
125.3 (p-CH), 128.5 (m-CH), 129.1 (o-CH), 141.6 (i-C),
9
2
NMR (300.1 MHz, CD2Cl2) δ 1.86 (dd, 1H, (H(2)), J = 9.6
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
3
2
3
Hz, J = 5.3 Hz), 2.32 (dd, 1H, (H(2)), J = 8.3 Hz, J = 5.3
2
3
Hz), 2.97 (t, 1H, (H(3)), J = J = 8.9 Hz), 3.46 and 3.78
(both s, 2 × 3H, 2 OMe), 6.76–6.94 (m, 2H, C6H4), 7.03–7.42
(m, 1H, C6H4)) ppm. 13C{1H} NMR (75.5 MHz, CD2Cl2) δ
20.2 (t, C(2), JCF = 4.5 Hz), 22.2 (t, C(3), JCF = 2.2 Hz),
34.5 (C(3)), 52.3 and 52.9 (2 OMe), 111.2 (d, C(1´), JCF
4
4
1
3
170.9 and 172.0 (2 COO). Isomer cis-4a. H NMR (400.1
MHz, CDCl3) δ 0.90 and 1.18 (both s, 2 × 3H, 2 Me at C(2)),
1.01 (d, 3H, Me at C(3), J = 7.0 Hz), 1.21–1.29 and 1.65–
=
2
10.4 Hz), 111.2 (d, C(3´), JCF = 25.3 Hz), 129.3 (t, C(4´),
3
3JCF = 10.4 Hz), 162.3 (dd, C(2´), JCF = 249.2, JCF = 7.4
Hz), 167.5 and 169.6 (2 COO) ppm. ). 19F NMR (CD2Cl2,
282.4 MHz)  –113.4 (br.s, 2 CF) ppm.
1
3
1.74 (both m, 2 × 1H, H2C(4)), 1.83–1.91 (m, 1H, (H(3)),
1.90 (dd, 1H, Ha, 2J = 12.4 Hz, 3J = 12.0 Hz), 2.70–2.82 (m,
1H, (H(5)), 3.15 (dd, 1H, Hb, 2J = 12.2 Hz, 3J = 2.6 Hz), 3.72
and 3.78 (both s, 2 × 3H, 2 OMe), 7.14–7.30 (m, 5H, Ph))
ppm. 13C{1H} NMR (100.6 MHz, CDCl3) δ 17.3 (Me at
C(3)), 20.6 and 31.1 (2 Me at C(2)), 38.1 (C(4)), 38.4 (CH2),
42.9 (C(3)), 45.8 (C(5)), 46.8 (C(2)), 51.5 and 51.8 (2 OMe),
71.6 (C(1)), 125.3 (p-CH), 128.4 (m-CH), 129.1 (o-CH),
141.5 (i-C), 170.6 and 171.7 (2 COO).
Dimethyl
2-(2,6-dichlorophenyl)cyclopropane-1,1-
~

dicarboxylate (1i). White solid. Yield 60%. IR (CHCl3):
3045, 3025, 3017, 2955, 1726 br (C=O), 1554, 1437, 1286,
1247, 1190 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C13H12Cl2O4Na 325.0005; Found 325.0012. 1H NMR
(300.1 MHz, CDCl3) δ 2.11 (dd, 1H, (H(2)), 2J = 9.6 Hz, 3J =
5.4 Hz), 2.46 (dd, 1H, (H(2)), J = 8.8 Hz, 3J = 5.4 Hz), 3.04
2
Dimethyl
5-(4-fluorobenzyl)-2,2,3-trimethylcyclo-
2
3
(t, 1H, (H(3)), J = J = 9.2 Hz), 3.48 and 3.83 (both s, 2 ×
3H, 2 OMe), 6.95–7.17 (m, 1H, C6H4), 7.23–7.28 (m, 2H,
C6H4)) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 24.7
(C(2)), 31.1 (C(3)), 35.8 (C(1)), 52.3 and 52.8 (2 OMe),
128.4 (CH(3´)), 128.8 (CH(4´)), 131.3 (CH(1´)) , 137.1
(CH(2´)), 167.8 and 169.5 (2 COO) ppm.
pentane-1,1-dicarboxylate (4b). The title compound was
prepared according to the general procedure from DAC 1b
(206 mg, 0.8 mmol), GaCl3 (158 mg, 0.9 mmol), and
tetramethylethylene 3 (226 mg, 2.7 mmol) in 107 mg yield
(39%) as a mixture of~two diastereomers (1:1). Colorless

thick oil. IR (CHCl3): 3043, 3008, 2977, 2895, 1720 br
Synthetic Procedure and Spectroscopic Data for
substituted cyclopentane-1,1-dicarboxylates 4. Solid GaCl3
(1.1−1.5 equiv) in one portion was added at convenient
temperature to a solution of cyclopropane 1 (1 equiv) in dry
CH2Cl2, and a mixture was stirred at the same temperature
until completion of the generation of formal 1,2-zwitterion 2
(optimal conditions: 1.1 equiv GaCl3, 0 °C, 10−15 min for
cyclopropanes 1a−c; 1.1 equiv GaCl3, 60−90 min, 0–5 °C for
cyclopropanes 1d or 1e; 1.4 equiv GaCl3, 25 °C, 45–60 min
for cyclopropanes 1f or 1i; 1.5 equiv GaCl3, 40 °C, 75 min
for cyclopropane 1g and 1.5 equiv GaCl3, 25 °C, 90 min for
cyclopropane 1h). Then a solution of alkene 3 (3–4 equiv) in
dry CH2Cl2 (1−2 mL) was added, and the reaction mixture
was immediately heated to 40 °C and refluxed for 2 h until
reaction was completed. After that, an aqueous solution of
HCl (10%) was added at room temperature until pH 3 was
achieved, and a reaction mixture was twice extracted with
CH2Cl2. The organic layer was dried over MgSO4, and the
solvent was removed in vacuo. The residue was purified by
column chromatography on silica gel (petroleum ether –
EtOAc, 10:1) to afford the title cyclopentane 4 as a thick
colorless oil. If it is necessary, the resulting compound 4 as a
mixture of two isomers may be additionally purified on a
Silufol chromatographic plate (20 × 20 cm), eluting with
petroleum ether − EtOAc (10:1) to give a compound
enriched with one of the diastereomers.
(C=O), 1435, 1242, 1189, 1046 cm–1. HRMS (ESI-TOF)
m/z: [M + Na]+ Calcd for C19H25FO4Na 359.1629; Found
1
359.1626. Isomer trans-4b. H NMR (300.1 MHz, CDCl3) δ
0.72 and 1.18 (both s, 2 × 3H, 2 Me at C(2)), 0.80 (d, 3H, Me
at C(3), J = 7.0 Hz), 1.25–1.34 and 1.68–1.77 (both m, 2 ×
1H, H2C(4)), 2.03 (t, 1H, Ha, J = J = 12.3 Hz), 2.66–2.79
3
2
3
2
(m, 1H, (H(3)), 2.90–2.99 (m, 1H, (H(5)), 3.03 (dd, Hb, J =
12.3 Hz, 3J = 2.5 Hz), 3.73 and 3.80 (both s, 2 × 3H, 2 OMe),
6.90–7.00 and 7.15–7.25 (both m, 2 × 2H, C6H4)) ppm.
13C{1H} NMR (75.5 MHz, CDCl3) δ 14.7 (Me at C(3)), 19.8
and 22.4 (2 Me at C(2)), 35.9 (C(4)), 38.1 (CH2), 42.9 (C(3)),
44.9 (C(5)), 48.4 (C(2)), 51.7 and 52.0 (2 OMe), 72.1 (C(1)),
2
3
115.0 (d, m-CH, JCF = 21.2 Hz), 130.2 (d, o-CH, JCF = 1.5
4
1
Hz), 137.0 (d, i-C, JCF = 1.5 Hz), 161.3 (d, p-C, JCF = 243
Hz)), 170.8 and 171.9 (2 COO). 19F NMR (CDCl3, 282.4
MHz)  –117.68 (tt, CF, JHF = 10.5 Hz, 4JHF = 5.7 Hz) ppm.
3
1
1
Isomer cis-4b. H NMR (300.1 MHz, CDCl3) δ H NMR
(300.1 MHz, CDCl3) δ 0.90 and 1.19 (both s, 2 × 3H, 2 Me at
C(2)), 1.02 (d, 3H, Me at C(3), J = 7.0 Hz), 1.22–1.31 and
1.81–1.90 (both m, 2 × 1H, H2C(4)), 1.66–1.76 (m, 1H,
(H(3)), 1.89 (t, 1H, Ha, 2J = 3J = 12.4 Hz), 2.66–2.78 (m, 1H,
(H(5)), 3.10 (dd, 1H, Hb, 2J = 12.4 Hz, 3J = 2.5 Hz), 3.72 and
3.78 (both s, 2 × 3H, 2 OMe), 6.90–7.00 and 7.15–7.25 (both
m, 2 × 2H, C6H4)) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ
17.3 (Me at C(3)), 20.5 and 31.1 (2 Me at C(2)), 37.5 (CH2),
38.0 (C(4)), 40.5 (C(3)), 44.9 (C(5)), 46.0 (C(2)), 51.7 and
3
2
Dimethyl
2,2,3-trimethyl-5-benzylcyclopentane-1,1-
51.9 (2 OMe), 71.5 (C(1)), 115.1 (d, m-CH, JCF = 21.2 Hz),
130.2 (d, o-CH, 3JCF = 1.5 Hz), 137.0 (d, i-C, 4JCF = 1.5 Hz),
161.3 (d, p-C, 1JCF = 243 Hz), 170.5 and 171.7 (2 COO). 19F
NMR (CDCl3, 282.4 MHz)  –117.66 (tt, CF, 3JHF = 10.1 Hz,
4JHF = 5.2 Hz) ppm.
dicarboxylate (4a). The title compound was prepared
according to the general procedure from DAC 1a (490 mg,
2.1 mmol), GaCl3 (410 mg, 2.3 mmol), and
tetramethylethylene 3 (530 mg, 6.3 mmol) in 450 mg yield
(67%) as a mixture of two diastereomers (1:1). Colorless
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Dimethyl
5-(4-chlorobenzyl)-2,2,3-trimethylcyclo-
OMe), 71.4 (C(1)), 122.5 (C(3´)), 127.7, 129.2, 130.0 and
132.0 (C(2´,4´,5´,6´)), 143.9 (C(1´)), 170.4 and 171.8 (2
COO).
pentane-1,1-dicarboxylate (4c). The title compound was
prepared according to the general procedure from DAC 1c
(226 mg, 0.8 mmol), GaCl3 (160 mg, 0.9 mmol), and
tetramethylethylene 3 (210 mg, 2.5 mmol) in 115 mg yield
Dimethyl
5-(2-chlorobenzyl)-2,2,3-trimethylcyclo-
pentane-1,1-dicarboxylate (4e). The title compound was
prepared according to the general procedure from DAC 1e
(282 mg, 1 mmol), GaCl3 (212 mg, 1.2 mmol), and
tetramethylethylene 3 (255 mg, 3 mmol) in 125 mg yield
(35%) as a mixture of~two diastereomers (2:1). Colorless
(40%) as a mixture of two diastereomers (1:1). Colorless
~

thick oil. Colorless thick oil. IR (CHCl3):
3047, 3020,
3007, 2976, 2895, 1721 br (C=O), 1447, 1435, 1268, 1243,
1236, 1047 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C19H25ClO4Na 375.1334; Found 375.1326. Found: m/z
353.1511, 375.1326. Isomer trans-4c. 1H NMR (300.1 MHz,
CDCl3) δ 0.72 and 1.18 (both s, 2 × 3H, 2 Me at C(2)), 0.81
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

thick oil. IR (CHCl3): 3032, 3007, 2976, 2895, 1722 br
(C=O), 1446, 1435, 1392, 1267, 1244, 1188, 1047 cm–1.
HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C19H27O4
353.1514; Found 353.1500. Isomer trans-4e. 1H NMR (300.1
MHz, CDCl3) δ 0.74 and 1.18 (both s, 2 × 3H, 2 Me at C(2)),
3
(d, 3H, Me at C(3), J = 7.0 Hz), 1.25–1.36 and 1.80–1.92
(both m, 2 × 1H, H2C(4)), 2.03 (t, 1H, Ha, 2J = 3J = 12.3 Hz),
2.68–2.79 (m, 1H, (H(3)), 2.90–3.01 (m, 1H, (H(5)), 3.04
(dd, 1H, Hb, 2J = 12.3 Hz, 3J = 2.6 Hz), 3.76 and 3.80 (both s,
2 × 3H, 2 OMe), 7.16–7.30 (m, 4H, C6H4) ppm. 13C{1H}
NMR (75.5 MHz, CDCl3) δ 14.7 (Me at C(3)), 19.8 and 22.4
(2 Me at C(2)), 35.9 (C(4)), 38.3 (CH2), 40.5 (C(3)), 44.8
(C(5)), 48.4 (C(2)), 51.7 and 51.9 (2 OMe), 72.0 (C(1)),
125.3 (m-CH), 130.3 (o-CH), 131.8 (p-C), 140.0 (i-C), 170.7
3
0.81 (d, 3H, Me at C(3), J = 7.0 Hz), 1.28–1.40 and 1.67–
1.80 (both m, 2 × 1H, H2C(4)), 2.39 (t, 1H, Ha, 2J = 3J = 12.4
Hz), 2.67–2.79 (m, 1H, (H(3)), 2.86–2.98 (m, 1H, (H(5)),
2
3
3.13 (dd, 1H, Hb, J = 12.4 Hz, J = 2.6 Hz), 3.76 and 3.81
(both s, 2 × 3H, 2 OMe), 7.10–7.24 and 7.25–7.36 (both m, 2
× 2H, Ar) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 14.7
(Me at C(3)), 19.9 and 22.5 (2 Me at C(2)), 35.4 and 35.6
((C(4) and CH2), 40.4 (C(3)), 44.2 (C(5)), 48.5 (C(2)), 51.7
and 52.0 (2 OMe), 72.2 (C(1)), 126.7, 127.5, 129.6 and 131.3
(C(3´,4´,5´,6´)), 134.2 (C(2´)), 138.9 (C(1´)), 170.5 and
171.8 (2 COO). Isomer cis-4e. 1H NMR (300.1 MHz,
CDCl3) δ 0.92 and 1.19 (both s, 2 × 3H, 2 Me at C(2)), 1.02
1
and 171.9 (2 COO). Isomer cis-4c. H NMR (300.1 MHz,
CDCl3) δ 0.90 and 1.19 (both s, 2 × 3H, 2 Me at C(2)), 1.03
(d, 3H, Me at C(3), J = 7.0 Hz), 1.22–1.33 (m, 1H, Ha(4)),
1.66–1.81 (m, 2H, H(3) and Hb(4)), 2.69–2.81 (m, 1H,
3
2
3
(H(3)), 1.87 (dd, Ha, J = 12.4 Hz, J = 12.0 Hz), 2.90–3.02
(m, 1H, (H(5)), 3.10 (dd, 1H, Hb, 2J = 12.4 Hz, J = 2.6 Hz),
3
3
(d, 3H, Me at C(3), J = 7.1 Hz), 1.22–1.35 (m, 1H, Ha(4)),
2
3.75 and 3.79 (both s, 2 × 3H, 2 OMe), 7.16–7.31 (m, 4H,
C6H4) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 17.3 (Me at
C(3)), 20.5 and 31.0 (2 Me at C(2)), 37.7 (C(4)), 37.9 (CH2),
42.9 (C(3)), 45.7 (C(5)), 46.7 (C(2)), 51.6 and 51.8 (2 OMe),
71.4 (C(1)), 128.5 (m-CH), 130.3 (o-CH), 131.8 (p-C), 139.9
(i-C), 170.5 and 171.6 (2 COO).
1.68–1.88 (m, 2H, Hb(4) and H(3)), 2.24 (dd, 1H, Ha, J =
12.4 Hz, 3J = 12.0 Hz), 3.10–3.24 (m, 2H, Hb and H(5)), 3.75
and 3.80 (both s, 2 × 3H, 2 OMe), 7.10–7.24 and 7.25–7.36
(both m, 2 × 2H, Ar) ppm. 13C{1H} NMR (75.5 MHz,
CDCl3) δ 17.2 (Me at C(3)), 20.5 and 31.0 (2 Me at C(2)),
35.1 (C(4)), 37.7 (CH2), 42.8 and 42.9 (C(3) and (C(5)), 46.8
(C(2)), 51.6 and 51.9 (2 OMe), 71.5 (C(1)), 126.7, 127.4,
129.6 and 131.2 (C(3´,4´,5´,6´)), 134.2 (C(2´)), 138.9
(C(1´)), 170.6 and 171.7 (2 COO).
Dimethyl
5-(3-bromobenzyl)-2,2,3-trimethylcyclo-
pentane-1,1-dicarboxylate (4d). The title compound was
prepared according to the general procedure from DAC 1d
(332 mg, 1 mmol), GaCl3 (205 mg, 1.2 mmol), and
tetramethylethylene 3 (267 mg, 3.2 mmol) in 172 mg yield
Dimethyl 5-(4-nitrobenzyl)-2,2,3-trimethylcyclopentane-
1,1-dicarboxylate (4f). The title compound was prepared
according to the general procedure from DAC 1f (94 mg,
0.33 mmol), GaCl3 (81 mg, 0.46 mmol), and
tetramethylethylene 3 (85 mg, 1 mmol) in 30 mg yield (24%)
as a mixture of two diastereomers (1.5:1). Colorless thick oil.
(41%) as a mixture of two diastereomers (1:1). Colorless
~
thick oil. IR (CHCl3):  3028, 3011, 2974, 2954, 2254, 1722
br (C=O), 1568, 1474, 1458, 1269, 1048, 1032 cm–1. HRMS
(ESI-TOF) m/z: [M + H]+ Calcd for C19H26BrO4 397.1009;
~
1
Found 397.0982. Isomer trans-4d. H NMR (300.1 MHz,
CDCl3) δ 0.72 and 1.17 (both s, 2 × 3H, 2 Me at C(2)), 0.80
(d, 3H, Me at C(3), J = 7.1 Hz), 1.25–1.38 and 1.64–1.77

IR (CHCl3):
3047, 3008, 2977, 2895, 1721 br (C=O),
1521, 1348 (NO2), 1242, 1189, 1047 cm–1. HRMS (ESI-
TOF) m/z: [M + Na]+ Calcd for C19H25NO6Na 386.1574;
Found 386.1559. Isomer trans-4f. 1H NMR (300.1 MHz,
CDCl3) δ 0.76 and 1.21 (both s, 2 × 3H, 2 Me at C(2)), 0.82
3
(both m, 2 × 1H, H2C(4)), 2.03 (t, 1H, Ha, 2J = 3J = 12.4 Hz),
2.67–2.80 (m, 1H, (H(3)), 2.92–3.05 (m, 1H, (H(5)), 3.06
(dd, 1H, Hb, 2J = 12.4 Hz, 3J = 2.6 Hz), 3.74 and 3.81 (both s,
2 × 3H, 2 OMe), 7.10–7.20 (m, 2H, C(4´) and C(6´)), 7.30–
7.38 (m, 1H, (H(5´), 7.40 (br.s, 1H, H(2´)) ppm. 13C{1H}
NMR (75.5 MHz, CDCl3) δ 14.7 (Me at C(3)), 19.8 and 22.4
(2 Me at C(2)), 35.9 (C(4)), 38.0 (CH2), 38.6 (C(3)), 42.9
(C(5)), 46.8 (C(2)), 51.7 and 52.0 (2 OMe), 72.1 (C(1)),
122.5 (C(3´)), 127.7, 129.2, 130.0 and 132.0 (C(2´,4´,5´,6´)),
3
(d, 3H, Me at C(3), J = 7.0 Hz), 1.26–1.38 (m, 1H, Ha(4)),
2
3
1.73 (ddd, 1H, Hb(4), J =13.2 Hz, J = 10.4 and 8.1 Hz),
2.22 (t, 1H, Ha, 2J = 3J = 12.4 Hz), 2.70–2.81 (m, 1H, (H(3)),
2
3
2.95–3.07 (m, 1H, (H(5)), 3.19 (dd, 1H, Hb, J = 12.4 Hz, J
= 2.7 Hz), 3.77 and 3.83 (both s, 2 × 3H, 2 OMe), 7.39–7.46
(m, 2H, H(2´,6´)), 8.14 (br.d, 2H, H(3´,5´), J = 7.8 Hz) ppm.
13C{1H} NMR (75.5 MHz, CDCl3) δ 14.5 (Me at C(3)), 19.6
and 22.3 (2 Me at C(2)), 35.8 (C(4)), 38.8 (CH2), 40.4 (C(3)),
44.4 (C(5)), 48.2 (C(2)), 51.7 and 52.0 (2 OMe), 72.0 (C(1)),
123.6 ((3´,5´)), 129.6 ((2´,6´)), 146.6 and 149.4 (C(1´) and
1
143.8 (C(1´)), 170.7 and 171.6 (2 COO). Isomer cis-4d. H
NMR (300.1 MHz, CDCl3) δ 0.91 and 1.18 (both s, 2 × 3H, 2
Me at C(2)), 1.02 (d, 3H, Me at C(3), 3J = 7.1 Hz), 1.22–1.36
and 1.63–1.76 (both m, 2 × 1H, H2C(4)), 1.82–1.93 (m, 1H,
1
C(4´)), 170.5 and 171.7 (2 COO). Isomer cis-4f. H NMR
2
3
(H(3)), 1.88 (dd, 1H, Ha, J = 12.4 Hz, J = 12.0 Hz), 2.67–
(300.1 MHz, CDCl3) δ 0.92 and 1.22 (both s, 2 × 3H, 2 Me at
2.80 (m, 1H, (H(5)), 3.06 (dd, 1H, Hb, 2J = 12.4 Hz, J = 2.6
3
3
C(2)), 1.03 (d, 3H, Me at C(3), J = 7.1 Hz), 1.23–1.34 and
Hz), 3.73 and 3.80 (both s, 2 × 3H, 2 OMe), 7.10–7.20 (m,
2H, C(4´) and C(6´)), 7.30–7.38 (m, 1H, (H(5´), 7.40 (br.s,
1H, H(2´)) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 17.3
(Me at C(3)), 20.5 and 31.0 (2 Me at C(2)), 37.9 (C(4)), 38.6
(CH2), 40.5 (C(3)), 44.6 (C(5)), 48.4 (C(2)), 51.6 and 51.9 (2
1.76–1.89 (both m, 2 × 1H, H2C(4)), 1.70–1.82 (m, 1H,
2
3
(H(3)), 2.05 (dd, Ha, J = 12.4 Hz, J = 12.0 Hz), 2.71–2.82
(m, 1H, (H(5)), 3.27 (dd, 1H, Hb, 2J = 12.4 Hz, J = 2.6 Hz),
3
3.78 and 3.84 (both s, 2 × 3H, 2 OMe), 7.39–7.46 (m, 2H,
H(2´,6´)), 8.14 (br.d, 2H, H(3´,5´), J = 7.8 Hz) ppm. 13C{1H}
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3
NMR (75.5 MHz, CDCl3) δ 17.1 (Me at C(3)), 20.4 and 30.9
1.02 (d, 3H, Me at C(3), J = 7.1 Hz), 1.35–1.47 and 1.78–
1.91 (both m, 2 × 1H, H2C(4)), 1.70–1.82 (m, 1H, (H(3)),
2
3
4
5
6
7
8
9
(2 Me at C(2)), 37.7 and 38.2 (C(4) and CH2), 42.8 (C(3)),
45.3 (C(5)), 46.6 (C(2)), 51.6 and 51.8 (2 OMe), 71.4 (C(1)),
123.6 ((3´,5´)), 129.6 ((2´,6´)), 146.6 and 149.3 (C(1´) and
C(4´)), 170.2 and 171.4 (2 COO).
2
2.20 (dd, Ha, J = 12.5 Hz, 3J = 12.0 Hz), 2.82–2.94 (m, 1H,
(H(5)), 3.27 (dd, 1H, Hb, 2J = 12.5 Hz, 3J = 2.6 Hz), 3.76 and
3.81 (both s, 2 × 3H, 2 OMe), 6.79–6.80 (m, 2H, H(3´,5´)),
7.07–7.20 (m, 1H, H(4´)) ppm. 13C{1H} NMR (75.5 MHz,
CDCl3) δ 17.1 (Me at C(3)), 20.6 and 30.9 (2 Me at C(2)),
24.5 (CH2), 35.3 (C(4)), 42.4 (C(3)), 43.3 (C(5)), 48.6 (C(2)),
51.7 and 52.0 (2 OMe), 71.5 (C(1)), 111.0 (dd, C(3´,5´), 2J =
17.7 Hz, 4J = 8.2 Hz), 116.6 (t, C(1´), 2J = 19.4 Hz), 127.5 (t,
Dimethyl 5-(3-nitrobenzyl)-2,2,3-trimethylcyclopentane-
1,1-dicarboxylate (4g). The title compound was prepared
according to the general procedure from DAC 1g (140 mg,
0.5 mmol), GaCl3 (115 mg, 0.65 mmol), and
tetramethylethylene 3 (125 mg, 1.5 mmol) in 56 mg yield
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
3
3
4
C(4´), J = 10.2 Hz), 161.7 (dd, C(2´,6´), J = 247 Hz, J =
8.9 Hz), 170.6 and 171.5 (2 COO). 19F NMR (CDCl3, 282.4
MHz)  –114.1 (br.t, 2 CF, JHF = 7 Hz) ppm.
(31%) as a mixture of two diastereomers (1:1). Colorless
~

thick oil. IR (CHCl3): 3047, 3007, 2977, 1722 br (C=O),
1530, 1351 (NO2), 1246, 1189, 1047 cm–1. HRMS (ESI-
TOF) m/z: [M + Na]+ Calcd for C19H25NO6Na 386.1574;
Dimethyl
5-(2,6-dichlorobenzyl)-2,2,3-trimethylcyclo-
1
pentane-1,1-dicarboxylate (4i). The title compound was
prepared according to the general procedure from DAC 1i
(334 mg, 1.1 mmol), GaCl3 (273 mg, 1.55 mmol), and
tetramethylethylene 3 (280 mg, 3.3 mmol) in 351 mg yield
(82%) as a mixture of two diastereomers (2:1). Colorless
thick oil. IR (CHCl3):  3049, 3005, 2975, 2954, 2878, 1724
Found 386.1569. Isomer trans-4g. H NMR (300.1 MHz,
CDCl3) δ 0.76 and 1.20 (both s, 2 × 3H, 2 Me at C(2)), 0.82
3
(d, 3H, Me at C(3), J = 7.0 Hz), 1.25–1.36 (m, 1H, Ha(4)),
1.70–1.82 (m, 1H, Hb(4)), 2.23 (t, 1H, Ha, 2J = 3J = 12.4 Hz),
2.70–2.81 (m, 1H, (H(3)), 2.96–3.07 (m, 1H, (H(5)), 3.19
(dd, 1H, Hb, 2J = 12.4 Hz, 3J = 2.8 Hz), 3.79 and 3.83 (both s,
~
3
2 × 3H, 2 OMe), 7.47 (br.t, 1H, H(5´), J = 7.6 Hz), 7.56–
br (C=O), 1561, 1446, 1435, 1269, 1244, 1184, 1048, 1032
cm–1. HRMS (ESI-TOF) m/z: [M
+
H]+ Calcd for
7.63 (m, 1H, H(6´)), 8.06–8.14 (m, 2H, H(2´,4´)) ppm.
13C{1H} NMR (75.5 MHz, CDCl3) δ 14.7 (Me at C(3)), 19.8
and 22.5 (2 Me at C(2)), 35.9 (C(4)), 38.7 (CH2), 40.6 (C(3)),
44.5 (C(5)), 48.5 (C(2)), 51.8 and 52.1 (2 OMe), 72.1 (C(1)),
121.4 (C(4´)), 123.8 (C(2´)), 129.3 (C(5´)), 135.3 (C(6´)),
143.6 (C(1´)), 148.5 (C(3´)), 170.6 and 171.8 (2 COO).
Isomer cis-4g. 1H NMR (300.1 MHz, CDCl3) δ 0.94 and 1.21
(both s, 2 × 3H, 2 Me at C(2)), 1.05 (d, 3H, Me at C(3), J =
7.2 Hz), 1.26–1.37 and 1.79–1.92 (both m, 2 × 1H, H2C(4)),
1.70–1.82 (m, 1H, (H(3)), 2.06 (dd, Ha, J = 12.5 Hz, J =
12.0 Hz), 2.69–2.80 (m, 1H, (H(5)), 3.27 (dd, 1H, Hb, J =
C19H25Cl2O4Na 387.1124; Found 387.1125. Isomer trans-4i.
1H NMR (300.1 MHz, CDCl3) δ 0.75 and 1.18 (both s, 2 ×
3
3H, 2 Me at C(2)), 0.78 (d, 3H, Me at C(3), J = 7.1 Hz),
1.07 (ddd, 1H, Ha(4), J = 13.3 Hz, J = 10.5 and 8.0 Hz),
2
3
2
3
1.98 (ddd, 1H, Ha(4), J = 13.3 Hz, J = 10.5 and 8.4 Hz),
2.62–1.74 (m, 1H, H(3)), 2.81 (t, 1H, Ha, J = 3J = 12.4 Hz),
2
3
2
3
3.18 (dd, 1H, Hb, J = 12.4 Hz, J = 4.3 Hz), 3.38–3.51 (m,
1H, (H(5)), 3.78 and 3.80 (both s, 2 × 3H, 2 OMe), 7.06 (dd,
1H, H(4´), J = 7.8 and 8.3 Hz), 7.27 (br.d, 2H, H(3´,4´), J = 8
Hz) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 14.8 (Me at
C(3)), 20.0 and 22.7 (2 Me at C(2)), 32.6 (CH2), 33.8 (C(4)),
40.3 (C(3)), 40.7 (C(5)), 48.6 (C(2)), 51.7 and 51.9 (2 OMe),
72.4 (C(1)), 127.7 (C(4´)), 128.5 (C(3´,5´)), 136.0 (C(2´,6´)),
2
3
2
12.5 Hz, 3J = 2.6 Hz), 3.78 and 3.84 (both s, 2 × 3H, 2 OMe),
7.47 (br.t, 1H, H(5´), 3J = 7.6 Hz), 7.56–7.63 (m, 1H, H(6´)),
8.06–8.14 (m, 2H, H(2´,4´)) ppm. 13C{1H} NMR (75.5 MHz,
CDCl3) δ 17.3 (Me at C(3)), 20.6 and 31.0 (2 Me at C(2)),
37.8 and 38.1 (C(4) and CH2), 42.9 (C(3)), 45.5 (C(5)), 46.8
(C(2)), 51.7 and 52.0 (2 OMe), 71.5 (C(1)), )), 121.4 (C(4´)),
123.8 (C(2´)), 129.3 (C(5´)), 135.3 (C(6´)), 143.6 (C(1´)),
148.5 (C(3´)), 170.4 and 171.6 (2 COO).
1
136.9 (C(1´)), 170.9 and 171.6 (2 COO). Isomer cis-4i. H
NMR (300.1 MHz, CDCl3) δ 0.95 and 1.19 (both s, 2 × 3H, 2
Me at C(2)), 0.98 (d, 3H, Me at C(3), 3J = 7.1 Hz), 1.53–1.78
(m, 3H, H(3) and H2C(4)), 2.70 (t, 1H, Ha, 2J = 3J = 12.4 Hz),
2
3
3.11–3.23 (m, 1H, (H(5)), 3.28 (dd, 1H, Hb, J = 12.4 Hz, J
= 4.3 Hz), 3.38–3.51 (m, 1H, (H(5)), 3.77 and 3.79 (both s, 2
× 3H, 2 OMe), 7.05 (dd, 1H, H(4´), J = 7.8 and 8.3 Hz), 7.27
(br.d, 2H, H(3´,4´), J = 8 Hz) ppm. 13C{1H} NMR (75.5
MHz, CDCl3) δ 16.9 (Me at C(3)), 20.5 and 30.9 (2 Me at
C(2)), 32.2 (CH2), 36.4 (C(4)), 41.9 (C(3)), 42.5 (C(5)), 46.9
(C(2)), 51.6 and 51.8 (2 OMe), 71.6 (C(1)), 127.8 (C(4´)),
128.5 (C(3´,5´)), 136.1 (C(2´,6´)), 136.9 (C(1´)), 170.5 and
171.5 (2 COO).
Dimethyl
5-(2,6-difluorobenzyl)-2,2,3-trimethylcyclo-
pentane-1,1-dicarboxylate (4h). The title compound was
prepared according to the general procedure from DAC 1h
(217 mg, 0.8 mmol), GaCl3 (195 mg, 1.1 mmol), and
tetramethylethylene 3 (203 mg, 2.4 mmol) in 172 mg yield
(60%) as a mixture of two diastereomers (1:1). Colorless
~

thick oil. Colorless thick oil. IR (CHCl3):
3033, 3009,
2977, 2895, 1724 br (C=O), 1250, 1242, 1189, 1046 cm–1.
HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C19H24F2O4Na
377.1535; Found 377.1533. Isomer trans-4h. 1H NMR
(300.1 MHz, CDCl3) δ 0.74 and 1.18 (both s, 2 × 3H, 2 Me at
Synthetic Procedure and Spectroscopic Data for
substituted
cyclopentane-1,1-dicarboxylates
9
and
alkylidenemalonates 10. Solid GaCl3 (1.5 equiv) in one
portion was added at 25 ° to a solution of cyclopropane 1i
(1.0 mmol) in dry CH2Cl2 (15 mL) and the mixture was
stirred 50–60 min at the same temperature until completion
of the generation of formal 1,2-zwitterion 2i. Then a solution
of alkenes 6 (4–5 equiv) in dry CH2Cl2 (1−2 mL) was added,
and the reaction mixture was immediately heated to 40 °C
and refluxed for 2–3 h. After that an aqueous solution of HCl
(10%) was added at room temperature until pH 3 was
achieved, and the reaction mixture was extracted with
CH2Cl2 (3 × 10 mL). The organic layer was dried over
MgSO4, and the solvent was removed in vacuo. The residue
was separated by column chromatography on silica gel
(petroleum ether – EtOAc, 10:1) to afford cyclopentane 9 as
a thick colorless oil (a mixture of two isomers) and
3
C(2)), 0.80 (d, 3H, Me at C(3), J = 7.1 Hz), 1.21–1.33 and
1.70–1.82 (both m, 2 × 1H, H2C(4)), 2.37 (br.t, 1H, Ha, J =
2
3J = 12.4 Hz), 2.66–2.79 (m, 1H, (H(3)), 2.80–2.91 (m, 1H,
(H(5)), 2.98–3.07 (m, 1H, Hb), 3.77 and 3.82 (both s, 2 × 3H,
2 OMe), 6.79–6.80 (m, 2H, H(3´,5´)), 7.07–7.20 (m, 1H,
H(4´)) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 14.7 (Me
at C(3)), 20.5 and 22.5 (2 Me at C(2)), 25.1 (CH2), 37.6
(C(4)), 40.3 (C(3)), 42.6 (C(5)), 47.0 (C(2)), 51.5 and 51.9 (2
OMe), 72.2 (C(1)), 111.1 (dd, C(3´,5´), 2J = 17.7 Hz, 4J = 8.2
2
3
Hz), 116.7 (t, C(1´), J = 19.8 Hz), 127.5 (t, C(4´), J = 10.2
Hz), 161.7 (dd, C(2´,6´), 1J = 247 Hz, 3J = 8.9 Hz), 170.4 and
171.4 (2 COO). 19F NMR (CDCl3, 282.4 MHz)  –114.9
(br.t, 2 CF, JHF = 7 Hz) ppm. Isomer cis-4h. 1H NMR (300.1
MHz, CDCl3) δ 0.92 and 1.19 (both s, 2 × 3H, 2 Me at C(2)),
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2
3
4
5
6
7
8
alkylidenemalonate 10. If it is necessary, the resulting
9b. 1H NMR (300.1 MHz, CDCl3) δ 1.67–1.82 (m, 2H,
H2C(4)), 1.77–1.90 and 2.24–2.37 (both m, 2 × 1H, H2C(3)),
compound 9 may be additionally purified on a Silufol
chromatographic plate (20 × 20 cm), eluting with petroleum
ether − EtOAc (10:1) to give a compound enriched with one
of the diastereomers.
2
3
2
2.85 (t, 1H, Ha, J = J = 12.6 Hz), 3.13 (dd, 1H, Hb, J =
12.6 Hz, 3J = 4.0 Hz), 3.20 and 3.82 (both s, 2 × 3H, 2 OMe),
3
3.32–3.46 (m, 1H, H(2)), 4.19 (t, 1H, H(5), J = 8.4 Hz),
6.90–7.00 (m, 2H, H(3´´,5´´)), 7.04–7.23 (m, 2H, H(2´´,6´´)),
7.25–7.35 (m, 3H, H(3´,4´,5´)) ppm. 13C{1H} NMR (75.5
MHz, CDCl3) δ 28.9 (C(4)), 32.0 (C(3)), 32.5 (CH2), 45.3
(C(2)), 50.9 (C(5)), 51.8 and 52.5 (2 OMe), 69.3 (C(1), 114.9
(d, C(3´´,5´´), 2JCF = 21.1 Hz), 128.1 (C(4´)), 128.6 (C(3´5´)),
Dimethyl 2-(2,6-dichlorobenzyl)-5-phenylcyclopentane-
1,1-dicarboxylate (9a) and dimethyl 1-(2,6-dichlorophenyl)-
5-phenylpent-2-ylidenemalonate (10a). The title compounds
were prepared according to the general procedure from DAC
1i (364 mg, 1.2 mmol), GaCl3 (300 mg, 1.7 mmol), and
allylbenzene 6a (428 mg, 3.6 mmol). Compound 9a was
isolated in 184 mg yield (36%) as a mixture of tw~o
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
3
130.2 (d, C(2´´,6´´), JCF = 8.2 Hz), 136.0 (C(2´,6´)), 136.5
4
1
(d, C(1´´), JCF = 7 Hz), 137.7 (C(1´)), 161.9 (d, C(4´´), JCF
= 243 Hz), 170.5 and 171.6 (2 COO). 19F NMR (CDCl3,
282.4 MHz)  –116.89 (tt, CF, JHF = 8.7 Hz, JHF = 4.8 Hz)
ppm. Isomer cis-9b. H NMR (300.1 MHz, CDCl3) δ 1.63–

diastereomers (1.5:1). Colorless thick oil. IR (CHCl3):
3
4
3051, 3022, 2953, 1723 br (C=O), 1435, 1281, 1257, 1244,
1186 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
C22H22Cl2O4Na 443.0787; Found 443.0785. Isomer trans-9a.
1H NMR (300.1 MHz, CDCl3) δ 1.71–1.84 (m, 2H, H2C(4)),
1.82–1.94 and 2.29–2.41 (both m, 2 × 1H, H2C(3)), 2.87 (t,
1
1.74 and 2.37–2.48 (both m, 2 × 1H, H2C(4)), 2.02–2.14 and
2.16–2.29 (both m, 2 × 1H, H2C(3)), 2.71–2.83 (m, 1H,
H(2)), 3.34 (dd, 1H, Ha, 2J = 13.2 Hz, 3J = 3.7 Hz), 3.40 and
3.78 (both s, 2 × 3H, 2 OMe), 3.54 (dd, 1H, Hb, 2J =13.2 Hz,
2
3
1H, Ha, J = J = 12.6 Hz), 3.17 and 3.85 (both s, 2 × 3H, 2
3
3J = 11.6 Hz), 4.06 (t, 1H, H(5), J = 9.7 Hz), 6.90–7.00 (m,
2
OMe), 3.18 (dd, 1H, Hb, J = 12.6 Hz, 3J = 4.0 Hz), 3.41–
2H, H(3´´,5´´)), 7.04–7.23 (m, 3H, H(4´,2´´,6´´)), 7.25–7.35
(m, 2H, H(3´,5´)) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ
28.2 (C(4)), 29.3 (C(3)), 31.4 (CH2), 48.4 (C(2)), 51.4 (C(5)),
3.53 (m, 1H, H(2)), 4.21 (t, 1H, H(5), 3J = 8.4 Hz), 7.06–7.37
(m, 8H, Ar and Ph) ppm. 13C{1H} NMR (75.5 MHz, CDCl3)
δ 29.0 (C(4)), 32.0 (C(3)), 32.5 (CH2), 45.5 (C(2)), 51.5
(C(5)), 51.6 and 52.2 (2 OMe), 69.5 (C(1), 126.8 (p-CH),
128.0, 128.4 and 128.6 (o-, m-CH and C(3´,5´)), 128.7
(C(4´)), 136.1 (C(2´,6´)), 136.7 (i-CH), 142.3 (C(1´)), 170.6
2
51.5 and 52.4 (2 OMe), 68.8 (C(1), 114.8 (d, C(3´´,5´´), JCF
= 21 Hz), 128.1 (C(4´)), 128.6 (C(3´5´)), 130.2 (d, C(2´´,6´´),
4
3JCF = 8.1 Hz), 136.0 (C(2´,6´)), 136.5 (d, C(1´´), JCF = 7
1
Hz), 137.7 (C(1´)), 161.8 (d, C(4´´), JCF = 244 Hz), 169.4
1
and 171.8 (2 COO). Isomer cis-9a. H NMR (300.1 MHz,
and 171.8 (2 COO). 19F NMR (CDCl3, 282.4 MHz)  –
116.81 (tt, CF, 3JHF = 8.8 Hz, 4JHF = 4.8 Hz) ppm.
CDCl3) δ 1.68–1.80 and 2.42–2.54 (both m, 2 × 1H, H2C(4)),
2.05–2.16 and 2.22–2.33 (both m, 2 × 1H, H2C(3)), 2.74–
2
2.86 (m, 1H, H(2)), 3.36 (dd, 1H, Ha, J = 13.2 Hz, 3J = 3.6
Compound 10b was isolated in 89 mg yield (40%).
~

Hz), 3.38 and 3.80 (both s, 2 × 3H, 2 OMe), 3.59 (dd, 1H,
Colorless thick oil. IR (CHCl3): 3061, 3006, 2957, 2931,
2
3
3
2872, 2405, 1722 br (C=O), 1510, 1436, 1249, 1049 cm–1.
Hb, J =13.2 Hz, J = 11.5 Hz), 4.12 (t, 1H, H(5), J = 9.7
Hz), 7.06–7.37 (m, 8H, Ar and Ph) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3) δ 28.4 (C(4)), 29.2 (C(3)), 31.4 (CH2),
48.6 (C(2)), 51.3 (C(5)), 52.0 and 52.3 (2 OMe), 69.0 (C(1),
126.9 (p-CH), 127.7, 127.8 and 127.9 (o-, m-CH and
C(3´,5´)), 128.4 (C(4´)), 136.0 (C(2´,6´)), 137.2 (i-CH),
140.2 (C(1´)), 169.5 and 171.9 (2 COO).
HRMS (ESI-TOF) m/z: [M
+
Na]+ Calcd for
C22H21Cl2FO4Na 461.0693; Found 461.0696. 1H NMR
(300.1 MHz, CDCl3) δ 1.52–1.68 (m, 2H, H2C(4)), 2.09–
2.19 (m, 2H, H2C(3)), 2.42 (t, 2H, H2C(5), 3J = 7.3 Hz), 3.74
and 3.81 (both s, 2 × 3H, 2 OMe), 4.27 (s, 2H, H2C(1)),
6.82–6.98 (m, 4H, o- and m-CH), 7.13 (dd, 1H, H(4´), J =
7.3 and 8.7 Hz), 7.21–7.29 (m, 2H, HC(3´,5´)) ppm. 13C{1H}
NMR (75.5 MHz, CDCl3) δ 30.5 (C(4)), 32.6 (C(3)), 35.3
and 35.6 (C(1) and C(5)), 52.2 and 52.3 (2 OMe), 115.0 (d,
Compound 10a was isolated~ in 108 mg yield (21%).

Colorless thick oil. IR (CHCl3): 3044, 3009, 2953, 2401,
1722 br (C=O), 1436, 1247, 1189 cm–1. HRMS (ESI-TOF)
2
m-CH, JCF = 21 Hz), 125.8 (C=), 128.5 (CH(3´,5´)), 128.9
m/z: [M + Na]+ Calcd for C22H22Cl2O4Na 443.0787; Found
3
(CH(4´)), 129.8 (d, o-CH, JCF = 7.8 Hz), 133.9 (C(1´)),
1
443.0791. H NMR (300.1 MHz, CDCl3) δ 1.55–1.70 (m,
4
136.8 (C(2´,6´)), 137.2 (d, i-C, JCF = 3.2 Hz), 158.3 (C(2)),
2H, H2C(4)), 2.08–2.19 (m, 2H, H2C(3)), 2.45 (t, 2H,
H2C(5), 3J = 7.4 Hz), 3.70 and 3.78 (both s, 2 × 3H, 2 OMe),
4.28 (s, 2H, H2C(1)), 6.99 (dd, 2H, o-CH), 7.08–7.29 (m, 6H,
HC(3´,4´,5´) and m-, p-CH) ppm. 13C{1H} NMR (75.5 MHz,
CDCl3) δ 30.4 (C(4)), 32.8 (C(3)), 35.6 (C(5)), 36.2 (C(1)),
52.2 and 52.3 (2 OMe), 125.9 (p-CH), 128.4, 128.5 and
128.6 (C(3´,5´), o- and m-CH), 128.5 (C=), 128.9 (C(4´)),
134.0 (C(1´)), 136.8 (C(2´,6´)), 141.6 (i-CH), 158.4 (C(2)),
166.0 and 161.1 (2 COO).
161.4 (d, p-C, 1JCF = 243 Hz), 165.8 and 166.0 (2 COO). 19F
3
NMR (CDCl3, 282.4 MHz)  –118.74 (tt, CF, JHF = 8.5 Hz,
4JHF = 5.6 Hz) ppm.
Dimethyl
2-(2,6-dichlorobenzyl)-5-(m-tolyl)cyclo-
pentane-1,1-dicarboxylate (9c). The title compound was
prepared according to the general procedure from DAC 1i
(122 mg, 0.4 mmol), GaCl3 (98 mg, 0.56 mmol), and 1-allyl-
4-methylbenzene 6c (155 mg, 1.2 mmol) in 53 mg yield
(30%) as a mixture of~two diastereomers (2:1). Colorless
Dimethyl
2-(2,6-dichlorobenzyl)-5-(4-fluorophenyl)-

thick oil. IR (CHCl3): 3045, 3006, 2959, 2403, 1723 br
cyclopentane-1,1-dicarboxylate (9b) and dimethyl 1-(2,6-
dichlorophenyl)-5-(4-fluorophenyl)pent-2-ylidenemalonate
(10b). The title compounds were prepared according to the
general procedure from DAC 1i (164 mg, 0.5 mmol), GaCl3
(125 mg, 0.7 mmol), and 1-allyl-4-fluorobenzene 6b (216
mg, 1.6 mmol). Compound 9b was isolated in 71 mg yield
(C=O), 1435, 1240, 1182, 1047 cm–1. HRMS (ESI-TOF)
m/z: [M + Na]+ Calcd for C23H24Cl2O4Na 457.0944; Found
1
457.0949. Compound 10c did not form. Isomer trans-9c. H
NMR (300.1 MHz, CDCl3) δ 1.72–1.84 (m, 2H, H2C(4)),
1.82–1.94 and 2.25–2.36 (both m, 2 × 1H, H2C(3)), 2.34 (s,
2
3
3H, Me), 2.88 (t, 1H, Ha, J = J = 12.5 Hz), 3.18 (dd, 1H,
Hb, 2J = 12.5 Hz, 3J = 4.0 Hz), 3.19 and 3.87 (both s, 2 × 3H,
2 OMe), 3.44–3.56 (m, 1H, H(2)), 4.19 (t, 1H, H(5), 3J = 8.5
Hz), 7.00–7.23 and 7.28–7.38 (both m, (5 + 2)H, Ar and
C6H4) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 21.6 (Me),
28.9 (C(4)), 32.0 (C(3)), 32.4 (CH2), 45.4 (C(2)), 51.6 (C(5)),
(32%) as a mixture of two diastereomers (1.7:1). Colorless
~

thick oil. IR (CHCl3): 3032, 3007, 2953, 2401, 1723 br
(C=O), 1512, 1436, 1282, 1257, 1186, 1161, 1052 cm–1.
HRMS (ESI-TOF) m/z: [M
+
Na]+ Calcd for
C22H21Cl2FO4Na 461.0693; Found 461.0690. Isomer trans-
12
ACS Paragon Plus Environment

Page 13 of 17
1
The Journal of Organic Chemistry
51.7 and 52.4 (2 OMe), 69.4 (C(1)), 125.7, 127.6, 127.8,
136.8 (C(2´,6´)), 139.7 (C(1´´)), 158.3 (C(2)), 165.7 and
2
3
4
5
6
7
8
9
128.0, 128.5, 128.7 and 129.6 (HCAr,Ar´), 136.1 (C(2´,6´)),
137.4 (i-C), 142.1 (C(1´)), 170.6 and 171.9 (2 COO). Isomer
cis-9c. 1H NMR (300.1 MHz, CDCl3) δ 1.67–1.79 and 2.40–
2.52 (both m, 2 × 1H, H2C(4)), 2.03–2.15 and 2.22–2.33
(both m, 2 × 1H, H2C(3)), 2.73–2.85 (m, 1H, H(2)), 3.36 (dd,
1H, Ha, 2J = 13.2 Hz, 3J = 3.7 Hz), 3.40 and 3.79 (both s, 2 ×
165.9 ((2 COO)).
Dimethyl 5-(2-bromophenyl)-1-(2,6-dichlorophenyl)pent-
2-ylidenemalonate (10e). The title compound was prepared
according to the general procedure from DAC 1i (122 mg,
0.4 mmol), GaCl3 (100 mg, 0.57 mmol), and 1-allyl-2-
bromobenzene 6e (235 mg, 1.2 mmol) in 96 mg yield (47%).
2
3
3H, 2 OMe), 3.60 (dd, 1H, Hb, J =13.0 Hz, J = 11.5 Hz),
4.08 (t, 1H, H(5), J = 9.8 Hz), 7.00–7.23 and 7.28–7.38
(Compound 9e did not form). Colorless thick oil. IR
3
~

(CHCl3): 3032, 3026, 3011, 2954, 2401, 1723 br (C=O),
(both m, (5 + 2)H, Ar and C6H4) ppm. 13C{1H} NMR (75.5
MHz, CDCl3) δ 21.5 (Me), 28.3 (C(4)), 29.3 (C(3)), 31.3
(CH2), 48.5 (C(2)), 51.4 (C(5)), 51.7 and 52.1 (2 OMe), 68.9
(C(1)), 125.9, 127.2, 127.6, 127.8, 128.0, 128.6 and 129.5
(HCAr,Ar´), 136.1 (C(2´,6´)), 137.2 (i-C), 140.2 (C(1´)), 169.5
and 171.9 (2 COO).
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1436, 1246, 1188, 1062 cm–1. HRMS (ESI-TOF) m/z: [M +
Na]+ Calcd for C22H21BrCl2O4Na 520.9892; Found 520.9888.
1H NMR (300.1 MHz, CDCl3) δ 1.56–1.69 (m, 2H, H2C(4)),
2.18–2.28 (m, 2H, H2C(3)), 2.60 (t, 2H, H2C(5), 3J = 7.5 Hz),
3.76 and 3.81 (both s, 2 × 3H, 2 OMe), 4.29 (s, 2H, H2C(1)),
3
7.00 (dd, 1H, H(4´), J = 7.2 and 8.2 Hz), 7.05 (br.d, 1H,
H(6´´), J = 7.4 Hz), 7.10–7.21 (m, 2H, H(4´´,5´´)), 7.27
3
Dimethyl 2-(2,6-dichlorobenzyl)-5-(o-tolyl)cyclopentane-
3
3
1,1-dicarboxylate (9d) and dimethyl 1-(2,6-dichlorophenyl)-
5-(o-tolyl)pent-2-ylidenemalonate
(br.d, 1H, H(3´,5´), J = 7.7 Hz), 7.47 (br.d, 1H, H(3´´), J =
8.0 Hz) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 29.0
(C(4)), 32.7 (C(3)), 35.7 (C(5)), 36.4 (C(1)), 52.3 and 52.5 (2
OMe), 124.5 (C(2´´)), 125.9 (C=), 127.4, 127.7 and 128.9
(C(4´´,5´´,6´´)), 130.5 (C(4´)), 132.9 (C(3´´)), 133.9 (C(1´)),
136.8 (C(2´,6´)), 140.9 (C(1´´)), 158.1 (C(2)), 165.8 and
166.0 ((2 COO)).
(10d).
The
title
compounds were prepared according to the general
procedure from DAC 1i (274 mg, 0.9 mmol), GaCl3 (230
mg, 1.3 mmol), 1-allyl-2-methylbenzene 6d (358 mg, 2.7
mmol). Compound 9d was isolated in 59 mg yield (15%) as a
mixture of~two diastereomers (3.5:1). Colorless thick oil. IR

(CHCl3):
3044, 3007, 2953, 2401, 1729 and 1719 br
Dimethyl
1-(2,6-dichlorophenyl)-6-phenylhex-2-
(C=O), 1562, 1492, 1436, 1275, 1258, 1180, 1047 cm–1.
HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for C23H24Cl2O4Na
457.0944; Found 457.0947. Isomer trans-9d. 1H NMR
(300.1 MHz, CDCl3) δ 1.68–1.90 (m, 3H, Ha(3) and H2C(4)),
2.26–2.38 (m, 1H, Hb(3)), 2.81 (t, 1H, Ha, 2J = 3J = 12.6 Hz),
3.10 and 3.88 (both s, 2 × 3H, 2 OMe), 3.25 (dd, 1H, Hb, 2J =
12.6 Hz, 3J = 4.0 Hz), 3.39–3.52 (m, 1H, H(2)), 4.59 (t, 1H,
ylidenemalonate (10f). The title compound was prepared
according to the general procedure from DAC 1i (153 mg,
0.5 mmol), GaCl3 (124 mg, 0.7 mmol), and 4-phenyl-1-
butene 6f (201 mg, 1.5 mmol) in 110 mg yield (50%).
(Compound 9f did not form). Colorless thick oil. IR (CHCl3):
~

3036, 3007, 2977, 2938, 1723 br (C=O), 1436, 1243, 1047
cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
3
H(5), J = 8.4 Hz), 7.05–7.20 and 7.28–7.38 (both m, (4 +
1
C23H24Cl2O4Na 457.0944; Found 457.0948. H NMR (300.1
3)H, C6H3 and C6H4) ppm. 13C{1H} NMR (75.5 MHz,
CDCl3) δ 20.5 (Me), 29.3 (C(4)), 32.4 (CH2), 33.4 (C(3)),
46.5 (C(2) and C(5)), 51.5 and 52.4 (2 OMe), 68.9 (C(1)),
126.0, 126.5, 127.3 127.9, 128.1, 128.5 and 129.9 (HCAr,Ar´),
136.0 (C(2´,6´)), 136.8, 137.4 and 141.4 (C(1´), C(1´´,2´´)),
MHz, CDCl3) δ 1.29–1.50 (m, 4H, 2 CH2), 2.12–2.22 (m,
2H, H2C(3)), 2.44 (t, 2H, H2C(6), 3J = 7.4 Hz), 3.75 and 3.78
(both s, 2 × 3H, 2 OMe), 4.29 (s, 2H, H2C(1)), 7.01–7.19 and
7.20–7.33 (both m, 2 × 4H, Ar and Ph) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3) δ 28.4 (C(4)), 31.5 and 32.8 (C(4,5)),
35.3 and 35.4 (C(1,6)), 52.1 and 52.2 (2 OMe), 125.6 (p-
CH), 125.9 (=C), 128.2 (C(3´,5´)), 128.3 (o- and m-CH),
128.9 (C(4´)), 133.9 (C(1´)), 136.7 (C(2´,6´)), 142.2 (i-CH),
158.4 (C(2)), 165.7 and 165.8 (2 COO) ppm.
1
170.5 and 172.2 (2 COO). Isomer cis-9d. H NMR (300.1
MHz, CDCl3) δ 1.70–1.82, 2.10–2.21, 2.25–2.37 and 2.46–
2.57 (all m, 4 × 1H, H2C(3) and H2C(4)), 2.63–2.75 (m, 1H,
H(2)), 3.29 and 3.81 (both s, 2 × 3H, 2 OMe), 3.38 (dd, 1H,
Ha, 2J = 13.2 Hz, 3J = 3.3 Hz), 3.72 (dd, 1H, Hb, 2J =13.2 Hz,
3J = 11.3 Hz), 4.47 (dd, 1H, H(5), 3J = 8.9 and 7.9 Hz), 7.05–
7.20 and 7.28–7.38 (both m, (4 + 3)H, C6H3 and C6H4) ppm.
13C{1H} NMR (75.5 MHz, CDCl3) δ 20.4 (Me), 30.4 and
32.7 (C(3) and C(4)), 31.0 (CH2), 47.2 (C(5)), 49.7 (C(2)),
51.3 and 52.7 (2 OMe), 68.9 (C(1), 125.6, 126.6, 127.5
127.8, 127.9, 128.1 and 130.2 (HCAr,Ar´), 136.1 (C(2´,6´)),
136.9, 137.7 and 140.4 (C(1´), C(1´´,2´´)), 170.0 and 172.1
(2 COO).
Dimethyl
2-(2,6-dichlorobenzyl)-5-ethylcyclopentane-
1,1-dicarboxylate (9g) and dimethyl 1-(2,6-dichloro-
phenyl)hept-2-ylidenemalonate (10g). The title compounds
was prepared according to the general procedure from DAC
1i (92 mg, 0.3 mmol), GaCl3 (75 mg, 0.42 mmol), and 1-
pentene 6g (64 mg, 0.9 mmol). Compound 9g was identified
by NMR in yield ~11% as a mixture of two diastereomers
(~1:1) and was not isolated in pure form. Colorless thick oil.
~

IR (CHCl3):
3025, 2955, 2254, 1723 br (C=O), 1435,
Compound 10d was isolated with ~65% purity in 160 mg
yield (25%, calcd on pure compound by NMR). Compound
10d has partially decomposed and polymerized ~ during

1240, 1218, 1192 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+
Calcd for C18H22Cl2O4Na 395.0787; Found 395.0792.
Compound 10g was isolated as a mixture with isomeric
compounds 11g–13g in 24% yield (by NMR). Colorless
thick oil. HRMS (ESI) calcd for C18H22Cl2O4: M + Na,
395.0787. Found: m/z 395.0790. 1H NMR (300.1 MHz,
chromatography. Colorless thick oil. IR (CHCl3):
3024,
3007, 2975, 2401, 1726 br (C=O), 1436, 1243, 1189, 1047
cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
1
C23H24Cl2O4Na 457.0944; Found 457.0941. H NMR (300.1
MHz, CDCl3) δ 1.48–1.64 (m, 2H, H2C(4)), 2.16–2.28 (m,
2H, H2C(3)), 2.16 (s, 3H, Me), 2.43 (t, 2H, H2C(5), J = 7.7
Hz), 3.71 and 3.78 (both s, 2 × 3H, 2 OMe), 4.27 (s, 2H,
H2C(1)), 6.88–7.20 (m, 7H, 7 H(Ar)) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3) δ 19.2 (Me), 29.3 (C(4)), 33.0 and 33.5
(C(3) and C(5)), 35.6 (C(1)), 52.1 and 52.2 (2 OMe), 125.8
(C=), 125.9, 126.0, 128.8 and 128.9 (C(3´´,4´´,5´´,6´´)),
128.4 (C(3´,5´)), 130.2 (C(4´)), 133.9 (C(1´)), 135.9 (C(2´´)),
3
CDCl3) δ 0.92 (t, 3H, Me, J = 7.0 Hz), 1.04–1.39 (m, 6H, 3
CH2), 2.05–2.23 (m, 2H, H2C(3)), 3.78 and 3.79 (both s, 2 ×
3H, 2 OMe), 4.29 (s, 2H, H2C(1)), 7.01–7.38 (m, 3H,
H(3´,4´,5´)) ppm.
3
Dimethyl 2-(2,6-dichlorobenzyl)-5-propylcyclopentane-
1,1-dicarboxylate (9h) and dimethyl 1-(2,6-dichloro-
phenyl)oct-2-ylidenemalonate (10h). The title compounds
was prepared according to the general procedure from DAC
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2
3
4
5
6
7
8
1i (92 mg, 0.4 mmol), GaCl3 (98 mg, 0.56 mmol), and 1-
hexene 6h (64 mg, 1.2 mmol). Compound 9h was isolated in
28.3, 30.6 and 31.5 (5 CH2), 34.1 (CH2Ar), 44.0 (C(2)), 47.0
C(5)), 51.4 and 52.1 (2 OMe), 66.5 (C(1)), 127.6 (C(4´)),
128.3 (C(3´,5´)), 135.8 (C(2´,6´)), 136.4 (C(1´), 170.1 and
172.1 (2 COO).
12.5 mg yield (20%) as a mixture of~ two diastereomers
(1.1:1). Colorless thick oil. IR (CHCl3):  3038, 3014, 2956,
2874, 2254, 1724 br (C=O), 1561, 1457, 1436, 1265, 1242,
1188, 1087 cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd
for C19H24Cl2O4Na 409.0944; Found 309.0946. Isomer trans-
9h. 1H NMR (300.1 MHz, CDCl3) δ 0.90 (t, 3H, Me, 3J = 7.2
Hz), 0.98–1.78, 1.82–1.97 and 2.02–2.19 (both m, (5+1+2)H,
4 CH2), 2.45–2.57 (m, 1H, H(5)), 2.72–2.85 (m, 1H, H(2)),
3.22–3.34 (m, 2H, CH2), 3.80 and 3.82 (both s, 2 × 3H, 2
Compound 10i was isolated~ in 34 mg yield (21%).

Colorless thick oil. IR (CHCl3): 3039, 3028, 3013, 2955,
2930, 2401, 1722 br (C=O), 1436, 1243, 1237, 1190, 1060,
1047 cm–1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C20H27Cl2O4 401.1281; Found 401.1280. 1H NMR (300.1
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
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55
56
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60
3
MHz, CDCl3) δ 0.84 (t, 3H, Me, J = 7.0 Hz), 1.05–1.38 (m,
10H, 5 CH2), 2.07–2.17 (m, 2H, H2C(3)), 3.79 (s, 6H, 2
3
3
OMe), 7.05 (dd, 1H, H(4´), J = 7.7 and 8.4 Hz), 7.26 (br.d,
OMe), 4.20 (s, 2H, H2C(1)), 7.15 (t, 1H, H(4´), J = 8.1 Hz),
3
2H, H(3´,5´), J = 8.1 Hz) ppm. 13C{1H} NMR (75.5 MHz,
7.29 (d, 2H, H(3´,5´), 3J = 8.1 Hz) ppm. 13C{1H} NMR (75.5
MHz, CDCl3) δ 14.1 (Me), 22.6, 28.67, 28.73, 29.8 and 31.6
(5 CH2), 33.1 (CH2(3)), 35.5 (CH2(1)), 52.16 and 52.17 (2
OMe), 125.3 (C=), 128.2 (CH(3´,5´)), 128.7 (CH(4´)), 134.2
(C(1´), 136.9 (C(2´,6´)), 158.9 (C(2)), 165.8 and 166.2 (2
COO).
CDCl3) δ 14.3 (Me), 21.7, 27.4, 28.4 and 31.6 (4 CH2), 32.5
(CH2Ar), 44.8 (C(2), 47.6 C(5)), 52.0 and 52.3 (2 OMe),
66.7 (C(1)), 127.8 (C(4´)), 128.5 (C(3´,5´)), 135.9 (C(2´,6´)),
1
137.2 (C(1´), 171.7 and 172.2 (2 COO). Isomer cis-9h. H
3
NMR (300.1 MHz, CDCl3) δ 0.91 (t, 3H, Me, J = 7.2 Hz),
0.98–1.78, 1.82–1.97 and 2.02–2.19 (both m, (5+1+2)H, 4
Dimethyl 2-(2,6-difluorobenzyl)-5-phenylcyclopentane-
1,1-dicarboxylate (9j). The title compounds were prepared
according to the general procedure from DAC 1h (190 mg,
0.7 mmol), GaCl3 (173 mg, 0.98 mmol), and allylbenzene 6a
(250 mg, 2.1 mmol). Compound 16 was isolated in 62 mg
2
CH2), 2.66–2.76 (m, 1H, H(2)), 2.88 (dd, 1H, Ha, J =13.0
3
2
3
Hz, J = 12.2 Hz), 2.94 (dd, 1H, Hb, J =13.0 Hz, J = 4.2
Hz), 3.10–3.22 (m, 1H, H(5)), 3.75 and 3.83 (both s, 2 × 3H,
2 OMe), 7.07 (dd, 1H, H(4´), 3J = 7.8 and 8.4 Hz), 7.26 (br.d,
2H, H(3´,5´), J = 8.1 Hz) ppm. 13C{1H} NMR (75.5 MHz,
3
yield (22%) as a mixture of two diastereomers (1.3:1).
CDCl3) δ 14.3 (Me), 21.5, 27.3, 31.6 and 34.2 (4 CH2), 34.2
(CH2Ar), 44.1 (C(2), 47.1 C(5)), 51.6 and 52.1 (2 OMe),
67.7 (C(1)), 127.9 (C(4´)), 128.6 (C(3´,5´)), 136.0 (C(2´,6´)),
136.6 (C(1´), 170.3 and 171.7 (2 COO).
~
Colorless thick oil. IR (CHCl3):  3005, 2969, 2955, 1730 br
(C=O), 1562, 1436, 1265, 1244, 1213, 1188, 1164, 1087 cm–
1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C22H22F2O4
389.1564; Found 389.1559. Isomer trans-9j. 1H NMR (300.1
MHz, CDCl3) δ 1.57–1.67 (m, 2H, H2C(4)), 1.86–1.94 and
2.29–2.39 (both m, 2 × 1H, H2C(3)), 2.16-2.25 (m, 1H, Ha),
), 3.02–3.05 (m, 1H, Hb), 3.18–3.24 (m, 1H, H(2)), 3.17 and
Compound 10h was isolated as a mixture with isomeric
compounds 11h–13h i~n 21% yield (by NMR). Colorless

thick oil. IR (CHCl3): 3006, 2976, 2896, 1724 br (C=O),
1436, 1245, 1187, 1046 cm–1. HRMS (ESI-TOF) m/z: [M +
Na]+ Calcd for C19H24Cl2O4Na 409.0944; Found 409.0947.
3
3.83 (both s, 2 × 3H, 2 OMe, 4.19 (t, 1H, H(5), J = 8.1 Hz),
6.85–6.92 (m, 2H, Ar and Ph), 7.14–7.37 (m, 6H, Ar and Ph)
ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 24.4 (C(3)), 29.2
(C(4)), 29.7 (CH2), 46.3 (C(2)), 51.7 (C(5)), 51.6 and 52.2 (2
3
1H NMR (300.1 MHz, CDCl3) δ 0.82 (t, 3H, Me, J = 7.0
Hz), 1.05–1.40 (m, 8H, 4 CH2), 2.05–2.20 (m, 2H, H2C(3)),
3.78 (s, 6H, 2 OMe), 4.28 (s, 2H, H2C(1)), 7.02–7.35 (m, 3H,
H(3´,4´,5´)) ppm.
3
OMe), 69.1 (C(1), 111.1 (t, C(3´), J = 6.5 Hz), 116.3 (t,
3
C(1´), 2J = 20.2 Hz), 126.8 (p-CH), 127.5 (t, C(4´), J = 10.1
Dimethyl
5-butyl-2-(2,6-dichlorobenzyl)cyclopentane-
Hz), 128.0 (o-CH), 128.6 (m-CH), 142.2 (i-CH), 161.6 (dd,
1,1-dicarboxylate (9i) and dimethyl 1-(2,6-dichloro-
phenyl)non-2-ylidenemalonate (10i). The title compounds
was prepared according to the general procedure from DAC
1i (93 mg, 0.4 mmol), GaCl3 (100 mg, 0.56 mmol), and 1-
heptene 6i (119 mg, 1.2 mmol). Compound 9i was isolated in
C(2´), 1J = 246.4 Hz, 3J = 8.8 Hz), 170.3 and 171.5 (2 COO).
1
Isomer cis-9j. H NMR (300.1 MHz, CDCl3) δ 1.84–1.94
and 2.26–2.41 (both m, 2 × 1H, H2C(4)), 2.05–2.13 and
2.29–2.38 (both m, 2 × 1H, H2C(3)), 2.53–2.61 (m, 1H,
H(2)), 3.07–3.13 (m, 1H, Hb), 3.21-3.25 (m, 1H, Ha), 3.41
and 3.80 (both s, 2 × 3H, 2 OMe), 4.01-4.06 (m 1H, H(5)),
6.85–6.92 (m, 2H, Ar and Ph), 7.14–7.37 (m, 6H, Ar and Ph)
ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 23.5 (C(3)), 29.1
(C(4)), 31.8 (CH2), 49.3 (C(2)), 51.3 and 52.3 (2 OMe), 52.2
51 mg yield (32%) as a mixture of two diastereomers (1.5:1).
~

Colorless thick oil. IR (CHCl3): 3007, 2955, 2934, 2873,
2861, 1724 br (C=O), 1561, 1436, 1263, 1187, 1087, 1045
cm–1. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd for
C20H26Cl2O4Na 423.1100; Found 423.1107. Isomer trans-9i.
1H NMR (300.1 MHz, CDCl3) δ 0.86–0.93 (m, 3H, Me),
0.93–2.22 (m, 10H, 5 CH2), 2.44–2.57 (m, 1H, H(5)), 2.72–
3
(C(5)), 68.7 (C(1), 110.9 (t, C(3´), J = 6.5 Hz), 116.9 (t,
3
C(1´), 2J = 20.2 Hz), 127.0 (p-CH), 127.5 (t, C(4´), J = 10.1
Hz), 127.8 (o-CH), 128.7 (m-CH), 139.8 (i-CH), 161.7 (dd,
C(2´), 1J = 246.4 Hz, 3J = 8.8 Hz), 169.2 and 171.9 (2 COO).
2
3
2.84 (m, 1H, H(2), 3.29 (t, 1H, Ha, J = J = 12.9 Hz), 3.31
(dd, 1H, Hb, 2J = 12.9 Hz, 3J = 7.9 Hz), 3.75 and 3.81 (both s,
2 × 3H, 2 OMe), 7.08 (dd, 1H, H(4´), J = 7.6 and 8.4 Hz),
7.27 (br.d, 2H, H(3´,5´), J = 7.7 Hz) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3) δ 14.0 (Me), 22.7, 27.3, 29.2, 30.4 and
31.4 (5 CH2), 32.4 (CH2Ar), 44.8 (C(2), 47.5 C(5)), 51.8 and
51.9 (2 OMe), 67.6 (C(1)), 127.8 (C(4´)), 128.3 (C(3´,5´)),
136.0 (C(2´,6´)), 137.0 (C(1´), 171.3 and 171.5 (2 COO).
Isomer cis-9i. 1H NMR (300.1 MHz, CDCl3) δ 0.86–0.93 (m,
3H, Me), 0.93–2.22 (m, 10H, 5 CH2), 2.67–2.78 (m, 1H,
H(5)), 2.86 (t, 1H, Ha, 2J = 3J = 12.8 Hz), 2.96 (dd, 1H, Hb, 2J
Dimethyl
2-(3-nitrobenzyl)-5-phenylcyclopentane-1,1-
dicarboxylate (9k). The title compounds were prepared
according to the general procedure from DAC 1g (100 mg,
0.35 mmol), GaCl3 (82 mg, 0.46 mmol), and allylbenzene 6a
(127 mg, 1.1 mmol). Compound 15 was isolated in 10 mg
yield (7%) as a mixture of two diastereomers (1.5:1).
~

Colorless thick oil. IR (CHCl3): 3039, 3032, 3021, 2953,
2254, 1724 br (C=O), 1625, 1592, 1470, 1435, 1267, 1240,
1189, 1060 cm–1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
1
C22H23NO6 398.1598; Found 398.1592. Isomer trans-9k. H
3
= 12.8 Hz, J = 4.3 Hz), 3.11–3.23 (m, 1H, H(2)), 3.79 and
NMR (300.1 MHz, CDCl3) δ 1.50–1.56 (m, 2H, H2C(4)),
1.86–1.94 and 2.36–2.43 (both m, 2 × 1H, H2C(3)), 2.21-
2.29 (m, 1H, Ha), 3.19 and 3.83 (both s, 2 × 3H, 2 OMe),
3.80 (both s, 2 × 3H, 2 OMe), 7.05 (dd, 1H, H(4´), J = 7.7
and 8.4 Hz), 7.28 (br.d, 2H, H(3´,5´), J = 7.7 Hz) ppm.
13C{1H} NMR (75.5 MHz, CDCl3) δ 14.0 (Me), 22.7, 27.2,
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3.23 (dd, 1H, Hb, J = 12.9 Hz, 3J = 3.4 Hz), 3.11–3.16 (m,
1H, H(2)), 4.14 (t, 1H, H(5), 3J = 8.0 Hz), 7.15–7.64 (m, 7H,
Ar and Ph), 8.09–8.13 (m, 2H, Ar and Ph) ppm. 13C{1H}
NMR (75.5 MHz, CDCl3) δ 29.8 (C(4)), 31.9 (C(3)), 37.9
(CH2), 48.1 (C(2)), 51.7 (C(5)), 51.7 and 52.3 (2 OMe), 68.9
(C(1), 121.4 (C(4´)), 123.7 (C(2´)), 126.9 (p-CH), 128.1 (o-
CH), 128.5 (m-CH), 129.3 (C(5´)), 135.2 (C(6´)), 142.2
(C(1´)), 143.0 (i-CH), 149.1 C(3´)), 170.4 and 171.5 (2
COO). Isomer cis-9k. 1H NMR (300.1 MHz, CDCl3) δ 1.85–
1.88 and 2.35–2.39 (both m, 2 × 1H, H2C(4)), 2.05–2.11 and
2.22–2.32 (both m, 2 × 1H, H2C(3)), 2.60–2.68 (m, 1H,
H(2)), 2.92 (dd, 1H, Hb, 2J =13.3 Hz, 3J = 11.2 Hz), 3.37 (dd,
1H, Ha, 2J = 13.3 Hz, 3J = 3.1 Hz), 3.45 and 3.79 (both s, 2 ×
3H, 2 OMe), 3.90-3.95 (m 1H, H(5)), 7.15–7.64 (m, 7H, Ar
and Ph), 8.09–8.13 (m, 2H, Ar and Ph) ppm. 13C{1H} NMR
(75.5 MHz, CDCl3) δ 29.1 (C(4)), 29.2 (C(3)), 37.1 (CH2),
50.5 (C(2)), 51.5 and 52.4 (2 OMe), 52.5 (C(5)), 68.5 (C(1),
121.3 (C(4´)), 123.6 (C(2´)), 127.1 (p-CH), 127.8 (o-CH),
128.8 (m-CH), 129.2 (C(5´)), 135.2 (C(6´)), 143.3 (C(1´)),
148.4 (i-CH), 149.1 C(3´)), 169.2 and 171.9 (2 COO).
2
*E-mail: novikovfff@bk.ru.
*E-mail: tom@ioc.ac.ru.
2
3
4
5
6
7
8
9
ORCID
Roman A. Novikov: 0000-0002-3740-7424
Yury V. Tomilov: 0000-0002-3433-7571
Author Contributions
§M.A.Z. and R.A.N. contributed equally.
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
This work was supported by the Russian Science
Foundation (grant no. 14-13-01054-P).
We are grateful to Dr. Anna V. Tarasova (N. D.
Zelinsky Institute of Organic Chemistry RAS, Moscow)
for participation in the experimental work. High
resolution mass spectra were recorded in the Department
of Structural Studies of N. D. Zelinsky Institute of
Organic Chemistry RAS, Moscow.19
Dimethyl 2-(2,6-dichlorobenzyl)-4-ethylcyclopent-3-ene-
1,1-dicarboxylate (14a) and dimethyl 5-(2,6-dichlorobenzyl)-
3-ethylcyclopent-2-ene-1,1-dicarboxylate
(14b).
These
REFERENCES
compounds were obtained according to the general
procedure from DAC 1i (93 mg, 0.4 mmol), GaCl3 (100 mg,
0.56 mmol), and methylenecyclobutane 6j (119 mg, 1.2
mmol), and were isolated in 78 mg yield (49%) as a mixture
of two re~gioisomers in ratio 2:1. Colorless thick oil. IR
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Substituted Cyclopropane Derivatives and Their Application
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(2) (a) Reissig, H. U.; Werz, D. B. (Guest Editorial),
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Chem. Commun. 2014, 50, 10912–10928.

(CHCl3): 3005, 2969, 2955, 1730 br (C=O), 1562, 1436,
1265, 1244, 1213, 1188, 1164, 1087 cm–1. HRMS (ESI-TOF)
m/z: [M + Na]+ Calcd for C18H20Cl2O4Na 393.0636; Found
1
393.0633. Isomer 14a: H NMR (300.1 MHz, CDCl3) δ 0.99
3
(t, 3H, Me, J = 7.4 Hz), 1.97–2.07 (m, 2H, CH2), 2.70 and
3.33 (both br.d, 2 × 1H, H2C(5), 2J = 16.7 Hz), 2.90–2.98 (m,
2H, CH2), 3.78 and 3.82 (both s, 2 × 3H, 2 OMe), 3.90–4.02
3
4
(m, 1H, H(2)), 4.92 (dt, 1H, H(3), J = 3.4 Hz, J = 1.6 Hz),
3
3
7.08 (t, 1H, H(4´), J = 8.2 Hz), 7.29 (d, 2H, H(3´,5´), J =
8.2 Hz) ppm. 13C{1H} NMR (75.5 MHz, CDCl3) δ 11.8
(Me), 22.9 (CH2 at C(4)), 32.4 (CH2 at C(2)), 42.3 (C(5)),
48.7 (C(2)), 52.4 and 52.8 (2 OMe), 63.7 (C(1)), 123.0
(C(3)), 127.9 (C(4´)), 128.4 (C(3´,5´)), 135.9 (C(2´,6´)),
136.0 (C(1´), 143.2 (C(4)), 171.0 and 172.6 (2 COO). Isomer
(3) Tomilov, Y. V.; Menchikov, L. G.; Novikov, R. A.;
Ivanova, O. A.; Trushkov, I. V. Methods for the synthesis of
donor-acceptor cyclopropanes. Russ. Chem. Rev. 2018, 87,
201–250.
1
3
14b: H NMR (300.1 MHz, CDCl3) δ 1.04 (t, 3H, Me, J =
7.4 Hz), 2.04–2.14 (m, 2H, CH2), 2.11–2.21 and 2.32–2.42
(m, 2 × 1H, H2C(4)), 3.04 (dd, 1H, Ha, 2J = 12.6 Hz, 3J = 3.8
(4) (a) Garve, L. K. B.; Jones, P. G.; Werz, D. B.
Ring‐Opening 1‐Amino‐3‐aminomethylation of Donor–
Acceptor Cyclopropanes via 1,3‐Diazepanes. Angew. Chem.
Int. Ed. 2017, 56, 9226–9230. (b) Das, S.; Daniliuc, C. G;
Studer, A. Stereospecific 1,3‐Aminobromination of
Donor‐Acceptor Cyclopropanes. Angew. Chem. Int. Ed.
2017, 129, 11712–11716. (c) Zhang, C.; Tian, J.; Ren, J.;
Wang, Z. Intramolecular Parallel [4+3] Cycloadditions of
Cyclopropane 1,1‐Diesters with [3]Dendralenes: Efficient
Construction of [5.3.0]Decane and Corresponding Polycyclic
Skeletons. Chem. Eur. J. 2017, 23, 1231–1236. (d) Suh, C.
W.; Kwon, S. J.; Kim, D. Y. Synthesis of Ring-Fused 1-
Benzazepines via [1,5]-Hydride Shift/7-Endo Cyclization
Sequences. Org. Lett. 2017, 19, 1334–1337. (e) Dey, R.;
Banerjee, P. Lewis Acid Catalyzed Diastereoselective
Cycloaddition Reactions of Donor–Acceptor Cyclopropanes
and Vinyl Azides: Synthesis of Functionalized
Azidocyclopentane and Tetrahydropyridine Derivatives.
Org. Lett. 2017, 19, 304–307. (f) Wallbaum, J.; Garve, L. K.
B.; Jones, P. G.; Werz, D. B. Ring-Opening 1,3-
Halochalcogenation of Cyclopropane Dicarboxylates. Org.
2
3
Hz), 3.19 (t, 1H, Hb, J = J = 12.6 Hz), 3.30–3.41 (m, 1H,
H(5)), 3.78 and 3.82 (both s, 2 × 3H, 2 OMe), 5.49 (dt, 1H,
3
4
3
H(2), J = 3.4 Hz, J = 1.6 Hz), 7.08 (t, 1H, H(4´), J = 8.2
Hz), 7.29 (d, 2H, H(3´,5´), J = 8.2 Hz) ppm. 13C{1H} NMR
3
(75.5 MHz, CDCl3) δ 11.7 (Me), 24.4 (CH2 at C(3)), 31.3
(CH2 at C(5)), 38.4 (C(4)), 44.0 (C(5)), 52.3 and 52.6 (2
OMe), 69.2 (C(1)), 120.9 (C(2)), 128.0 (C(4´)), 128.5
(C(3´,5´)), 136.0 (C(2´,6´)), 136.4 (C(1´), 152.0 (C(3)), 171.4
and 172.6 (2 COO).
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge
on the ACS Publications website at DOI:
1H and 13C NMR spectra for all pure products (PDF)
AUTHOR INFORMATION
Corresponding Authors
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Lett. 2017, 19, 98–101. (g) Pandey, A. K.; Varshnaya, R. K.;
Chem. 2017, 82, 2724–2738. (b) Novikov, R. A.; Borisov, D.
Banerjee, P. Substituent and Lewis Acid Promoted Dual
Behavior ofEpoxides towards [3+2]-Annulation Reactions
with Donor-Acceptor Cyclopropanes: Synthesis of
Substituted Cyclopentaneand Tetrahydrofuran. Eur. J. Org.
Chem. 2017, 1647–1656.
D.; Tarasova, A. V.; Tkachev, Y. V.; Tomilov, Y. V.
Three‐Component Gallium(III)‐Promoted Addition of Halide
Anions and Acetylenes to Donor‐Acceptor Cyclopropanes.
Angew. Chem. Int. Ed. 10.1002/anie.201803541.
(11) Borisov, D. D.; Novikov, R. A.; Tomilov, Y. V.
(a) Augustin, A. U.; Busse, M.; Jones, P. G.; Werz, D. B.
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