Lewis acid-mediated reactions of donor-acceptor cyclopropanes with diazo esters

Article abstract of DOI:10.1007/s11172-018-2069-8

The reactions of diazo esters with 2-arylcyclopropane-1,1-dicarboxylates, the represen- tatives of donor-acceptor cyclopropanes (DACs), mediated by Sc(OTf)₃, SnCl₄, and GaCl₃ proceeded with nitrogen elimination to give the

Full text of DOI:10.1007/s11172-018-2069-8

Russian Chemical Bulletin, International Edition, Vol. 67, No.2, pp. 265—273, February, 2018
265
Lewis acidꢀmediated reactions of donorꢀacceptor cyclopropanes
with diazo esters
R. A. Novikov, D. D. Borisov, and Yu. V. Tomilov
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
4
7 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 6390. Eꢀmail: tom@ioc.ac.ru
The reactions of diazo esters with 2ꢀarylcyclopropaneꢀ1,1ꢀdicarboxylates, the represenꢀ
tatives of donorꢀacceptor cyclopropanes (DACs), mediated by Sc(OTf) , SnCl , and GaCl
3
3
4
proceeded with nitrogen elimination to give the C—C coupling products. No products of the
formal [3+3] cycloaddition of diazo compounds to DACs were formed but the main reaction
direction was addition of diazo ester to either 1,3ꢀ or 1,2ꢀzwitterions generated upon Lewis
acidꢀmediated cyclopropane ring opening giving rise to new 1,4ꢀ and 1,3ꢀzwitterionic interꢀ
mediates. The formed intermediates underwent further fragmentations and rearrangements
to give substituted cyclopropanediꢀ, ꢀtriꢀ, and ꢀtetracarboxylates. Mechanistic aspects of the
observed reactions were discussed.
Key words: donorꢀacceptor cyclopropanes, diazo esters, Lewis acids, C—C bond formation.
Cyclopropanes bearing vicinal donor and acceptor
substituents (donorꢀacceptor cyclopropanes, DACs) can
and more complex cascade processes27—30 and, thereꢀ
fore, found wide applications in modern organic syntheꢀ
sis. Cycloaddition reactions are the most characteristic
transformations for this class of cyclopropanes and most
often associated exactly with these compounds. For inꢀ
stance, the reactions of 1,3ꢀzwitterions generated from
1
be readily activated by Lewis acids to give 1,3ꢀzwitterionꢀ
ic intermediates resulting from threeꢀmembered ring
2
—8
opening.
These zwitterions readily underwent
—12
13—23
24—26
[
3+2],9
[3+3],
and [3+4] cycloadditions
Scheme 1
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 0265—0273, February, 2018.
066ꢀ5285/18/6702ꢀ0265 © 2018 Springer Science+Business Media, Inc.
1

2
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Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
Novikov et al.
DACs with other 1,3ꢀdipoles manly proceed as the forꢀ
mal [3+3] cycloaddition to afford sixꢀmembered heteroꢀ
cycles (Scheme 1, A). Among these reactions, the reacꢀ
cyclopropaneꢀ1,1ꢀdicarboxylate (1a) with diazoacetate 2a
under different conditions (Table 1).
In the presence of mild Lewis acids, e.g., Ni(ClO ) ,
4
2
1
3—15
tions of DACs with nitrones
are the most deeply
In(OTf) , and Yb(OTf) , the reactions do not take place.
3 3
1
6
17
studied. The reactions involving azides, nitrile imines,
A strong Lewis acid, Sc(OTf) , facilitates the reaction
3
nitronates,1
8,19
and azomethine imines are also known.
20
and stronger Lewis acids (SnCl , TiCl , GaCl ) cause
4
4
3
All these processes are extensively employed in synthetic
organic chemistry and were used to achieve total syntheꢀ
a relatively fast transformation of both starting compoꢀ
nents. The reactions practically stop both at low temperꢀ
atures (below –90 °C) and in the presence of different
2
1—23
ses of several natural compounds.
.
However, diazo compounds have not yet been studied
as 1,3ꢀdipoles for these reactions. It is known that diazo
compounds are able to play a role of 1,3ꢀdipoles in [3+2]
ligands (pyridine, Et N) used to control the Lewis acidiꢀ
3
ty. Performing the reactions in the presence of Rh (OAc)4
2
and Rh (OAc) /Sc(OTf) results only in decomposition
2
4
3
cycloadditions involving substrates with different multiꢀ
of diazoacetate 2a to dimethyl fumarate and dimethyl
maleate.
ple bonds.3
1—33
The aim of the present work is the extenꢀ
sion of these processes to the reactions involving DACs,
i.e., the attempts to realize the formal [3+3] cycloaddiꢀ
tions producing tetrahydropyridazines (Scheme 1, B). It
should be emphasized that Doyle and coꢀworkers3 have
described the reaction between DACs and enol diazoꢀ
acetates, which proceeded as common [3+2] cycloaddiꢀ
tion of 1,3ꢀzwitterion to the vinyl double bond followed
by ring expansion via rhodiumꢀcatalyzed dediazotization
Screening of Lewis acids and the reaction conditions
revealed four main directions of chemical transformaꢀ
tions of DAC 1a in the reaction with diazoacetate 2a
(Scheme 2). Unfortunately, neither lowering the reaction
temperature, nor changing the solvents and reagent ratios
allow us to perform the formal [3+3] cycloaddition of 1a
to 2a and obtain tetrahydropyridazine. All identified prodꢀ
ucts contain no nitrogen thus indicating the complete
dediazotization of the starting diazo ester. Nevertheless,
the coupling of DAC and diazo ester proceeds efficiently
with the C—C bond formation. In nearly all cases, the
main reaction products were methyl cinnamate 3a and
cyclopropaneꢀ1,1,2ꢀtricarboxylate (4) (see Scheme 2,
Table 1). Unluckily, the obtained products are of low
synthetic value but the process itself has some theoretical
interest.
4
(
Scheme 1, C).
Results and Discussion
Apparently, the absence of the published examples of
a formal [3+3] cycloaddition of DACs to diazo comꢀ
pounds is not a simple gap. This process is very difficult
to realize taking into account lability of diazo compounds
in the presence of the Lewis acids35,36 used for the activaꢀ
tion of the DAC cyclopropane rings. With the aim to
study the possible directions of the reactions of DACs
with diazo compounds, we tested the performance of
a series of Lewis acids in a model reaction of 2ꢀphenylꢀ
An explanation of the formation of compounds 3a
and 4 is shown on Scheme 3. The reaction of 1,3ꢀzwitterꢀ
ion I initially generated from DAC with diazo ester in the
presence of Lewis acid1 via the C—C bond formation
to give unstable intermediate II, which readily eliminates
the nitrogen molecule. Theoretically, intermediate II can
—8
Scheme 2
3a (up to 92%)
4 (up to 67%)

Reactions of diazo esters with DꢀA cyclopropanes
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
267
Table 1. Lewisꢀacid mediated reactions of dimethyl 2ꢀphenylcyclopropaneꢀ1,1ꢀdicarboxylate (1a) with diazoacetate 2a
Ratio
Lewis
acid
mol.%)
Reaction
conditions
Conversion
of 1a
Yields of the reaction products (%)b
a
1
a : 2a
3
a
4
5a
6a
7a
9
(
(%)
T/°C
–78
25
t/h
0.5
0.1
0.1
0.2
1
(E/Z)
(dr)
(E/Z)
1
1
1
1
1
1
1
1
1
1
1
1
: 1
SnCl4
164
100
157
178
100
100
186
100
100
142
196
110
47
(1 : 1.6)
92
(1 : 1.2)
41
(1 : 1.7)
47
(1.4 : 1)
72
(1.3 : 1)
63
(1 : 1.7)
63
(1 : 3.7)
71
(1 : 3.4)
39
32
48
34
18
24
52
58
67
47
11
34
—
12
—
—
11
—
14
—
—
—
10
25
—
—
—
—
—
—
—
—
4
(
100)
SnCl4
200)
GaCl3
20)
GaCl3
20)
GaCl3
40)
GaCl3
20)
GaCl3
100)
GaCl3
100)
GaCl3
150)
Sc(OTf)3
10)
Sc(OTf)3
20)
Yb(OTf)3
10)
: 1.5
: 1.1
: 1.5
: 1.4
: 2
(
25
5
(1 : 2)
8
(1 : 2)
6
(1 : 2)
11
(1 : 4)
18
(1 : 3.5)
23
(1 : 3.5)
15
3
(5 : 1)
—
(
25c
25c
25
(
7
—
6
8
(
(5 : 1)
16
(5 : 1)
—
2
(
: 2
–50
–50
0–5
25
6
—
—
8d
—
—
—
(
: 2
10
—
(
: 2
0.2
3
19
(
(1 : 1.7)
21
(1 : 1.2)
47
(1 : 1.3)
—
(1 : 1.9) (5.7 : 1)
: 1
7
(1 : 1.2)
14
(1 : 1.4)
—
—
(
: 2
25
6
3
(5 : 1)
—
(
: 2
25
72
(
a
b
In CH Cl .
2
2
Total yields of the products can be greater than 100%, since compounds 3a and 4 result from fragmentation of
the activated complexes (see Scheme 3).
c
In diethyl ether.
d
Compound 10a (see Scheme 6) was also isolated in 23% yield (trans/cis = 1 : 1.4).
cyclize to tetrahydropyridazine ring A and further to tauꢀ
tomer B but we failed to detect these intermediates in the
reaction mixtures also by low temperature (–30 °C) NMR
experiments. A nitrogen elimination gives 1,4ꢀzwitterꢀ
ionic intermediate III; this intermediate is unstable due to
the presence of the acceptor group destabilizing its posiꢀ
tive charge and undergoes fast transformations. The main
directions of these transformations are the fragmentation
Scheme 3
LA is Lewis acid.

2
68
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
Novikov et al.
of intermediate III with the C—C bond cleavage and forꢀ
mation of two alkene species, compound 3a and dimethyl
compounds 5a, 6a, and 7a as the main products. Thus,
20% Sc(OTf) enable a formal insertion of diazo ester
3
2
2
ꢀmethylidenemalonate (Scheme 3, pathway a). Next,
ꢀmethylidenemalonate undergoes Lewis acidꢀmediated
into the C—H bond of the starting cyclopropane 1a to
give compound 5a. In the reactions carried out in the
reaction with an excess of the starting diazo ester 2a proꢀ
ducing cyclopropanetricarboxylate 4 and also partially
polymerizes.
The other revealed directions of the process give reꢀ
gioisomers 5a, 6a, and 7a and are more synthetically inꢀ
teresting (see Scheme 2) despite the lower product yields
than in the reactions resulting in compounds 3a and 4.
We succeeded to find the reaction conditions that give
presence of GaCl , the structure of the product depends
3
3
5
on the reaction temperature. Thus, at –50 °C compound
6a, the product of formal diazo ester insertion into the
C—Ph bond is formed; while, at room temperature the
reaction is also accompanied with the threeꢀmembered
ring opening to produce 3ꢀphenylbutꢀ2ꢀeneꢀ1,1,4ꢀtricarbꢀ
oxylate (7a) (see Scheme 2, Table 1). These reactions
require the excess of diazoacetate since it is partially conꢀ
sumed by the reaction with methylidenemalonate and is
partially destroyed by Lewis acid. It should be noted that
the compositions of the products of the reactions of DAC
Scheme 4
1
a with diazoacetate 2a generally depend not only on the
nature of the Lewis acid but also on the reaction temperꢀ
ature and the solvent used (see Table 1).
The formation of regioisomers 5a, 6a, and 7a also
proceeds via zwitterionic intermediate III undergoing eiꢀ
ther a hydride shift (Scheme 4, pathway b) or an aryl shift
(
pathway c) to give 1,3ꢀzwitterionic intermediates IV and V.
Zwitterions IV and V readily cyclize into the correꢀ
sponding cyclopropanes 5a and 6a, respectively. These
compounds are relatively stable and do not undergo furꢀ
ther transformations. Under more drastic conditions, inꢀ
termediate IV is partially converted into isomeric butꢀ2ꢀ
enetricarboxylates 7a. Interestingly, neither reactions
show the evidence of formation of substituted cyclobuꢀ
tane 8, however this product could be formed by cyclizaꢀ
tion of zwitterion III (pathway d).
Other reaction products were isolated in some cases,
for instance, compounds 9 and 10a, along with the alꢀ
ready described compounds. Compound 9 can arise from
successive addition of diazoacetate 2a to the methylideneꢀ
malonate intermediate and further to 1,2ꢀzwitterion VI
(
Scheme 5).
Scheme 5

Reactions of diazo esters with DꢀA cyclopropanes
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
269
Scheme 6
A key step in the pathway leading to cyclopropane
0a is generation of 1,2ꢀzwitterion VII upon treatment of
was proved to be the most suitable Lewis acid for this
transformation providing compounds 3b, 4, and 6b as the
main products. Note that this reaction gives the higher
yield of cyclopropane 9 than the reaction of DAC 1a
(Scheme 7).
1
3
7—43
DAC 1a with GaCl at 0—5 °C.
The reaction of
3
intermediate VII with 2a after dediazotization results in
cyclopropane derivative 10a (Scheme 6). It should be
underlined that both these reactions similarly to the
formation of compounds 5a and 6a proceed as the ring
closure of the corresponding 1,3ꢀzwitterions to the threeꢀ
membered rings.
Besides diazoacetate 2a, diazomalonate 2b also reacts
with DAC 1a (Scheme 8); however, to enable this reacꢀ
tion more active Lewis acid, GaCl , should be employed
3
instead of Sc(OTf) . The number of minor products in
3
Cyclopropanetricarboxylate 9 is identified as the cis
isomer and compound 10a is a 1 : 1.4 mixture of trans and
cis isomers.
this reaction was lower than in the case of diazoacetate
2a; however, the yields of the main expected products,
e.g., compound 3c, were also noticeably lower. Note the
relatively high yield of cyclopropane 10c; similarly to
cyclopropane 10a, derivative 10c is formed via 1,2ꢀzwitꢀ
terionic intermediate VII.3
2
ꢀ(2ꢀThienyl)cyclopropaneꢀ1,1ꢀdicarboxylate (1b)
reacts with diazoacetate 2a similarly; however, in this
7—43
reaction both SnCl and GaCl gave no satisfactory reꢀ
4
3
sults since they caused almost complete polymerization
of the starting DAC. Scandium(III) triflate (Sc(OTf)3)
To minimize the role of intermediate I (see Scheme 3)
in the reactions with diazo esters and, conversely, to
Scheme 7
Scheme 8

2
70
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
Novikov et al.
Scheme 9
enhance the role of 1,2ꢀzwitterion VII (see Scheme 6),
we preliminary generated this zwitterion from cycloproꢀ
internal standard. The NMR signals were attributed and isoꢀ
meric compositions were established by homoꢀ and heteroꢀ
nuclear 1D (DEPTꢀ135) and 2D (COSY, TOCSY, NOESY,
HSQC, editedꢀHSQC, and HMBC) correlation techniques. IR
spectra were recorded on a IRꢀFourierꢀtransform spectrometer
pane 1a and GaCl at 0—5 °C (1,2ꢀzwitterion VII is stable
3
4
4,45
at this temperature within several hours
) and studied
its behavior in the reactions with diazoacetate 2a. Indeed,
in this case the product composition differed from that
obtained by the simultaneous mixing of all reagents. Exꢀ
pectedly, the formation of cyclopropanetricarboxylate 10a
was the main pathway of this reaction (Scheme 9); howꢀ
ever, unsaturated triester 12 was also obtained in relatꢀ
ively high yield (26%). Among the minor products 13—15,
it should be mentioned the formation of cyclobutanecarbꢀ
oxylates 14 and 15. Compound 13 was identified as two
diastereomers with the trans arranged cyclopropane ring
substituents.
in CHCl (0.5—2%). Electron impact (EI) mass spectra were
3
run on a Finnigan MAT INCOSꢀ50 instrument using 70 eV
electrons. High resolution electrospray ionization (ESI) mass
spectrometry was performed with a Bruker micro TOFII inꢀ
strument.46 Thin layer chromatography was carried out on the
precoated plates Merck Silica gel 60 F254. Preparative chromatoꢀ
graphy was performed with Merck silica gel 60 (0.040—0.063 mm).
All manipulations with anhydrous GaCl (Aldrich) were carꢀ
3
ried out under dry argon. The solvents (purity no less than
9
9.5%) were used as purchased. Dichloromethane used in the
reactions with GaCl was first dried over KOH pellets and then
3
distilled over P O under dry argon.
2
5
In summary, we pioneered in studying the reactions
of DACs with diazo esters mediated by Lewis acids, e.g.,
Reactions of cyclopropanes 1a,b with diazo compounds 2a,b
(general procedure). To a solution of cyclopropane 1a,b
(0.6 mmol) and diazo compound 2a,b (1.2—1.5 mmol) in anꢀ
hydrous dichloromethane (5—7 mL), Lewis acid (Sc(OTf)3,
Sc(OTf) , SnCl , and GaCl , using 2ꢀarylcyclopropaneꢀ
3
4
3
1
,1ꢀdicarboxylates 1 as the models. Depending on the
5
—20 mol.%; SnCl , 1.2 mmol; GaCl , 0.6—0.9 mmol) was
reaction conditions, all observed transformations proceed
as the C—C bond forming reactions accompanied with
the nitrogen molecule elimination. No products of the
formal [3+3] cycloaddition of diazo compounds to DACs
were detected in any of the reactions. The main direcꢀ
tions of the reactions of DACs with diazo esters are addiꢀ
tions of diazo esters to 1,3ꢀ and 1,2ꢀzwitterionic intermeꢀ
diates generated upon the Lewis acidꢀmediated opening
of the DAC cyclopropane ring. Subsequent elimination
of the nitrogen molecule generates 1,4ꢀ and 1,3ꢀzwitterꢀ
ionic intermediates, which undergo fragmentation and
rearrangement to give substituted cyclopropanes bearing
either two, three or four ester groups per molecule.
4 3
added at the selected temperature (see Table 1) under argon.
The reactions were carried out with stirring under the condiꢀ
tions specified in Schemes 2, 7, and 8 and in Table 1. Then the
reaction mixture was treated with 5% HCl (7 mL) and extractꢀ
ed with dichloromethane (3×10 mL). The combined organic
layers were dried with anhydrous MgSO4 and concentrated
in vacuo. The obtained products were isolated and purified by
either column or preparative thin layer chromatography (silica
gel, elution with benzene and ethyl acetate mixed in different
ratios). To resolve the isomers and isolate pure products,
a sequence of several chromatography steps was used if required.
Methyl 3ꢀphenylacrylate (3a), a 1 : 1.2 mixture of E and Z
isomers, was synthesized following the general procedure from
cyclopropane 1a (141 mg, 0.6 mmol), diazoacetate 2a (120 mg,
1
5
.2 mmol), and SnCl4 (312 mg, 1.2 mmol) at 25 °C within
Experimental
min. Total yield 89 mg (92%); colorless oils. The isomers
1
13
were resolved. H and C NMR spectra are in agreement with
those published earlier.
1H and 13C NMR spectra were recorded with Bruker AMXꢀIII
47,48
4
00 (working frequencies of 400.1 and 100.6 MHz, respectively)
and Bruker AVANCE II 300 (working frequencies of 300 and
5 MHz, respectively) instruments in CDCl . The chemical
Trimethyl cyclopropaneꢀ1,1,2ꢀtricarboxylate (4) was synꢀ
thesized following the general procedure from cyclopropane 1a
(141 mg, 0.6 mmol), diazoacetate 2a (120 mg, 1.2 mmol), and
7
3
shifts are given in the δ scale relative to Me Si (0.05%) as an
SnCl (312 mg, 1.2 mmol) at 25 °C within 5 min. Yield 62 mg
4
4

Reactions of diazo esters with DꢀA cyclopropanes
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
271
1
13
(
48%); colorless oil. H and C NMR spectra are in agreement
(2 COO). MS (ESI): found m/z 329.0992. C16H18O . Calculatꢀ
6
ed: 329.0996 [M + Na] . Z Isomer. H NMR (400.1 MHz,
4
9
+
1
with those published earlier.
Dimethyl 2ꢀ(2ꢀmethoxyꢀ2ꢀoxoethyl)ꢀ2ꢀphenylcyclopropaneꢀ
,1ꢀdicarboxylate (5a) was synthesized following the general
procedure from cyclopropane 1a (141 mg, 0.6 mmol), diazoaceꢀ
tate 2a (120 mg, 1.2 mmol), and Sc(OTf) (59 mg, 0.12 mmol)
at 25 °C within 6 h. Yield 45 mg (25%); colorless oil. H NMR
4
CDCl ), δ: 3.44 (d, 2 H, CH , J = 1.1 Hz); 3.60 (s, 3 H,
3
2
3
1
CO Me); 3.72 (s, 6 H, 2 CO Me); 4.11 (d, 1 H, H(1), J =
2 2
= 10.2 Hz); 5.91 (dt, 1 H, H(2), J = 10.2 Hz, 4J = 1.1 Hz);
3
7.14—7.38 (m, 5 H, Ph). 1 C NMR (100.6 MHz, CDCl ),
3
3
3
1
δ: 44.4 (CH (4)), 51.9 (OMe), 52.2 (CH(1)), 52.8 (2 OMe), 122.6
2
2
(
(
2
400.1 MHz, CDCl ), δ: 1.89 (d, 1 H, H(3), J = 5.7 Hz); 2.39
(CH(2)), 128.0 (CH(p)), 128.3 and 128.6 (2 CH(o) and 2 CH(m)),
138.2 (C(ipso)), 139.9 (C(3)), 168.5 (COO), 171.0 (2 COO).
Reaction of dimethyl 2ꢀ(2ꢀthienyl)cyclopropaneꢀ1,1ꢀdicarbꢀ
oxylate (1b) with diazoacetate 2a was carried out following the
general procedure. The reaction of cyclopropane 1b (144 mg,
0.6 mmol), diazoacetate 2a (150 mg, 1.5 mmol), and Sc(OTf)3
(30 mg, 0.06 mmol) at 25 °C for 3 h gave compounds 3b (59%),
4 (28%), 6b (18%), and 9 (14%), which were isolated pure.
Methyl 3ꢀ(2ꢀthienyl)acrylate (3b), a 1 : 2.5 mixture of E and
Z isomers. Total yield 59 mg (59%). The isomers were resolved;
3
2
4
dd, 1 H, H(3), J = 5.7, J = 1.2 Hz); 2.80 (d, 1 H, H(1´),
J = 16.0 Hz); 3.14 (dd, 1 H, H(1´), J = 16.0 Hz, J = 1.2 Hz);
.31 (s, 3 H, CO Me); 3.55 (s, 3 H, CO Me); 3.81 (s, 3 H,
CO Me); 7.15—7.38 (m, 5 H, HAr). C NMR (100.6 MHz,
CDCl ), δ: 24.5 (C(3)), 38.3 (C(2)), 39.4 (C(1)), 41.0 (C(1´)),
2
4
3
2
2
1
3
2
3
5
(
(
3
1.6, 52.3 and 52.9 (3 OMe), 127.6 (C(p)), 128.2 and 129.3
2 C(o) and 2 C(m)), 138.3 (C(ipso)), 167.3, 169.2 and 171.2
3 COO). MS (ESI): found m/z 329.0983. C H O . Calculated:
1
6
18
6
+
29.0996 [M + Na] .
1
13
Dimethyl 2ꢀ(2ꢀmethoxyꢀ2ꢀoxoꢀ1ꢀphenylethyl)cyclopropaneꢀ
,1ꢀdicarboxylate (6a), two diastereomers in a 1 : 3.5 ratio, was
both isomers are colorless oils. H and C NMR spectra are in
agreement with those published earlier.4
7,50
1
synthesized following the general procedure from cycloproꢀ
pane 1a (141 mg, 0.6 mmol), diazoacetate 2a (120 mg, 1.2 mmol),
Dimethyl 2ꢀ[2ꢀmethoxyꢀ2ꢀoxoꢀ1ꢀ(2ꢀthienyl)ethyl]cycloꢀ
propaneꢀ1,1ꢀdicarboxylate (6b), a 1 : 1.4 mixture of two diaꢀ
stereomers. Total yield 33 mg (18%); colorless oil. H NMR
1
and GaCl (106 mg, 0.6 mmol) at –50 °C within 10 h. Total
3
yield 42 mg (23%); colorless oil. Diastereomers were resolved.
(400.1 MHz, CDCl ), δ: 1.46—1.60 (m, 3 H, 2 Hmajor(3) and
3
1
2
3
Major diastereomer. H NMR (400.1 MHz, CDCl ), δ: 1.42
Hminor(3)); 1.73 (dd, 1 H, H
(3), J = 5.1 Hz, J = 7.6 Hz);
minor
3
2
3
3
3
3
(
2
dd, 1 H, H(3), J = 5.1 Hz, J = 9.1 Hz); 1.47 (dd, 1 H, H(3),
J = 5.1 Hz, J = 7.8 Hz); 2.65 (ddd, 1 H, H(2), J = 11.1 Hz,
J = 9.1 Hz, 3J = 7.8 Hz); 3.16 (d, 1 H, H(2´), J = 11.1 Hz);
2.63 (ddd, 1 H, Hmajor(2), J = 11.0 Hz, J = 9.1 Hz, J = 7.6 Hz);
3
3
3
3
3
2.73 (ddd, 1 H, Hminor(2), J = 11.0 Hz, J = 9.1 Hz, J = 7.6 Hz);
3
3
3
3.48 (d, 1 H, H
(1´), J = 11.0 Hz); 3.67 (d, 1 H, Hminor(1´),
major
3
3
.68 (s, 3 H, CO Me); 3.75 (s, 3 H, CO Me); 3.79 (s, 3 H,
J = 11.0 Hz); 3.70 (s, 3 H, CO Meminor); 3.71 (s, 3 H,
2
2
2
1
3
CO Me); 7.22—7.41 (m, 5 H, HAr). C NMR (100.6 MHz,
CO Me
); 3.72 (s, 3 H, CO Meminor); 3.73 (s, 3 H,
2
2
major
major
2
CDCl ), δ: 20.0 (C(3)), 30.4 (C(2)), 34.6 (C(1)), 51.1 (C(2´)),
CO Me
); 3.74 (s, 3 H, CO Memajor); 3.77 (s, 3 H,
3
2
2
5
2
2.3, 52.8 and 52.9 (3 OMe), 127.90 and 129.0 (2 C(o) and
CO Me
); 6.90—7.00 (m, 3 H, H ); 7.02 (dd, 1 H, H
,
2
major
Ar
Ar,minor
3
3
3
C(m)), 127.92 (C(p)), 137.5 (C(ipso)), 168.5, 169.9 and 172.6
J = 5.1 Hz, J = 3.8 Hz); 7.19 (dd, 1 H, H
, J = 5.0 Hz,
, J = 5.1 Hz, J = 3.8 Hz).
Ar,minor
Ar,major
+
3
1
3
3
(
(
3 COO). MS (EI), m/z (Irel (%)): 306 (2), [M] , 288 (2), 274
40), 242 (24), 233 (2), 214 (44), 210 (43), 199 (7), 186 (42),
J = 1.4 Hz); 7.23 (dd, 1 H, H
3
C NMR (100.6 MHz, CDCl ), δ: 20.1 and 21.2 (C(3)), 30.6
3
1
1
3
85 (21), 171 (7), 155 (28), 143 (7), 128 (67), 121 (17), 115 (76),
and 30.7 (C(2)), 33.4 and 34.5 (C(1)), 45.5 and 46.3 (C(1´)),
52.5, 52.6, 52.7, 52.8, 52.9 (6 OMe), 125.1, 125.2, 125.7, 126.6,
126.9 and 128.1 (6 CHAr), 139.2 and 139.4 (C(2″)), 168.3, 169.2,
05 (17), 91 (43), 77 (36), 59 (100). MS (ESI): found m/z
+
29.0989. C16
H
1
O . Calculated: 329.0996 [M + Na] . Minor
18
6
diastereomer. H NMR (400.1 MHz, CDCl ), δ: 1.58 (dd, 1 H,
169.5, 169.6, 171.6 and 171.9 (6 COO). MS (ESI). Found: m/z
3
2
3
2
+
H(3), J = 5.0 Hz, J = 9.1 Hz); 1.75 (dd, 1 H, H(3), J = 5.0 Hz,
335.0555. C14H16O S. Calculated: 335.0560 [M + Na] .
6
3
3
3
J = 7.6 Hz); 2.81 (ddd, 1 H, H(2), J = 11.0 Hz, J = 9.1 Hz,
J = 7.6 Hz); 3.37 (d, 1 H, H(2´), J = 11.0 Hz); 3.46 (s, 3 H,
Trimethyl (2RS,3SR)ꢀ3ꢀ(2ꢀmethoxyꢀ2ꢀoxoethyl)cyclopropꢀ
aneꢀ1,1,2ꢀtricarboxylate (9). Yield 24 mg (14%), colorless oil.
3
3
1
CO Me); 3.68 (s, 3 H, CO Me); 3.69 (s, 3 H, CO Me);
7
H NMR (400.1 MHz, CDCl ), δ: 2.28 (ddd, 1 H, H(3),
2
2
2
3
1
3
3
3
3
3
.04—7.39 (m, 5 H, HAr). C NMR (100.6 MHz, CDCl ),
J = 9.6 Hz, J = 8.5 Hz, J = 6.9 Hz); 2.73 (d, 1 H, H(2),
3
2
3
δ: 21.4 (C(3)), 29.5 (C(2)), 33.4 (C(1)), 50.4 (C(2´)), 52.3
3 OMe), 127.7 (C(p)), 127.9 and 128.6 (2 C(o) and 2 C(m)),
37.2 (C(ipso)), 168.5, 169.8 and 172.9 (3 COO). MS
J = 9.6 Hz); 2.89 (dd, 1 H, H(1´), J = 17.8 Hz, J = 8.5 Hz);
2
3
(
1
3.03 (dd, 1 H, H(1´), J = 17.8 Hz, J = 6.9 Hz); 3.70 (s, 3 H,
CO Me); 3.71 (s, 3 H, CO Me); 3.75 (s, 3 H, CO Me); 3.76
(s, 3 H, CO Me). C NMR (100.6 MHz, CDCl ), δ: 27.6 (C(3)),
2 3
2
2
2
1
3
(
[
ESI): found m/z 329.0996. C16H18O . Calculated: 329.0996
M + Na] .
6
+
28.7 (C(1´)), 29.8 (C(2)), 38.5 (C(1)), 51.9, 52.3, 52.8 and 53.4
Trimethyl 3ꢀphenylbutꢀ2ꢀeneꢀ1,1,4ꢀtricarboxylate (7a),
a 5.7 : 1 mixture of E and Z isomers, was synthesized following
the general procedure from cyclopropane 1a (141 mg,
.6 mmol), diazoacetate 2a (120 mg, 1.2 mmol), and GaCl3
106 mg, 0.6 mmol) at 0–5 °C within 10 min. Total yield 34 mg
(4 OMe), 165.5, 168.8, 169.0 and 172.2 (4 COO). MS (ESI).
+
Found: m/z 311.0743. C H O . Calculated: 311.0737 [M + Na] .
12
16 8
Reaction of cyclopropane 1a with diazomalonate 2b was carried
out by the general procedure. The reaction of cyclopropane 1a
(141 mg, 0.6 mmol), diazomalonate 2b (190 mg, 1.2 mmol), and
0
(
(
19%); colorless oil. The isomers were partially resolved;
GaCl (106 mg, 0.6 mmol) at 25 °C for 3 h gave compounds
3
1
E isomer was isolated pure. E Isomer. H NMR (400.1 MHz,
3c (22%), 11 (19%), 6c (6%), and 10c (23%), which were isoꢀ
lated pure.
CDCl ), δ: 3.58 (s, 2 H, CH ); 3.64 (s, 3 H, CO Me); 3.78 (s, 6 H,
3
2
2
3
2
3
CO Me); 4.50 (d, 1 H, H(1), J = 9.8 Hz); 6.24 (d, 1 H, H(2),
Dimethyl 2ꢀbenzylidenemalonate (3c). Yield 29 mg (22%),
2
1
13
J = 9.8 Hz); 7.24—7.37 (m, 3 H, metaꢀH and paraꢀH);
colorless oil. H and C NMR spectra are in agreement with
1
3
51
7
.39–7.45 (m, 2 H, orthoꢀH). C NMR (100.6 MHz, CDCl ),
those published earlier.
3
δ: 36.4 (CH (4)), 52.1 (CH(1)), 52.2 (OMe), 53.0 (2 OMe),
Tetramethyl cyclopropaneꢀ1,1,2,2ꢀtetracarboxylate (11).
Yield 31 mg (19%), colorless oil. H and C NMR spectra are
in agreement with those published earlier.52
2
1
13
1
22.9 (CH(2)), 126.4 and 128.7 (2 CH(o) and 2 CH(m)), 128.1
(
CH(p)), 137.6 (C(ipso)), 141.0 (C(3)), 168.1 (COO), 170.8

2
72
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
Novikov et al.
Dimethyl 2ꢀ(1,3ꢀdimethoxyꢀ1,3ꢀdioxoꢀ2ꢀphenylpropꢀ2ꢀyl)ꢀ
and 3.84 (all s, 3 H each, 3 CO Me); 7.21—7.33 (m, 5 H, Ph).
2
cyclopropaneꢀ1,1ꢀdicarboxylate (6c). Yield 13 mg (6%), colorꢀ
MS (ESI). Found: m/z 329.0985. C16H18O . Calculated:
329.0996 [M + Na] .
6
less oil. 1H NMR (400.1 MHz, CDCl ), δ: 1.64 (dd, 1 H,
+
3
2
3
CH (3)ꢀa, J = 5.0 Hz, J = 9.9 Hz); 1.91 (dd, 1 H, CH (3)ꢀb,
J = 5.0 Hz, J = 8.5 Hz); 2.75 (dd, 1 H, CH(2), J = 8.5 Hz,
J = 9.9 Hz); 3.61, 3.72, 3.75, and 3.76 (all s, 3 H each, 4 CO Me);
.28—7.42 (m, 5 H, Ph). C NMR (100.6 MHz, CDCl ),
3
2
2
2
3
3
This work was financially supported by the Council
on Grants of the President of the Russian Federation
(Program for State Support of Young PhDꢀScientists,
Grant MKꢀ3465.2017.3).
3
2
1
3
7
δ: 18.4 (CH (3)), 32.8 (CH(2)), 33.8 (C(1)), 52.5, 53.0, 53.1,
2
and 53.2 (4 OMe), 62.6 (C(1´)), 128.02 (C(p)), 128.04 and
1
28.4 (2 C(o) and 2 C(m)), 137.4 (C(ipso)), 167.4, 169.6, 169.7,
References
and 170.8 (4 COO). MS (ESI). Found: m/z 387.1041. C H O .
Calculated: 387.1050 [M + Na] .
1
8
20
8
+
Tetramethyl 3ꢀbenzylcyclopropaneꢀ1,1,2,2ꢀtetracarboxylate
1 Yu. V. Tomilov, L. G. Menchikov, R. A. Novikov, O. A.
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25, 1.
1
(
10c). Yield 50 mg (23%), colorless oil. H NMR (400.1 MHz,
3
CDCl ), δ: 2.76 (t, 1 H, H(3), J = 7.5 Hz); 3.21 (d, 2 H, H(1´),
3
3
J = 7.5 Hz); 3.74 (s, 6 H, 2 CO Me); 3.46 (s, 6 H, 2 CO Me);
2
2
1
3
6
2
(
.78—7.46 (m, 5 H, HAr). C NMR (100.6 MHz, CDCl ), δ:
3
8.8 (C(1´)), 36.5 (C(3)), 44.0 (C(1) and C(2)), 52.9 and 53.3
4 OMe), 126.4 (C(p)), 128.3 and 128.5 (2 C(o) and 2 C(m)),
39.0 (C(ipso)), 165.1 and 166.9 (4 COO). MS (ESI). Found:
1
+
m/z 387.1045. C18H20O . Calculated: 387.1050 [M + Na] .
8
Reaction of cyclopropane 1a with diazoacetate 2a under conꢀ
ditions of preliminary generation of 1,2ꢀzwitterion VII. To a soꢀ
lution of cyclopropane 1a (141 mg, 0.6 mmol) in anhydrous
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dichloromethane (6 mL), solid GaCl (106 mg, 0.6 mmol) was
3
added at 5 °C under argon. After 15 min stirring, a solution of
diazoacetate 2a (120 mg, 1.2 mmol) in dichloromethane
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fe, A. O. Terent´ev, V. A. Vil´, Yu. V. Tomilov, R. A. Noꢀ
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(
2 mL) was added and the resulting mixture was stirred at 15 °C
for 15 min. Then 5% HCl (7 mL) was added and the mixture
was extracted with dichloromethane (3×10 mL). The combined
organic layers were dried with anhydrous MgSO and concenꢀ
4
trated in vacuo. The products were isolated and purified by
silica gel column chromatography (elution with benzene—ethyl
acetate, 10 : 1). Compounds 10a (49%) and 12 (26%) were
isolated pure. Compounds 13—15 were not isolated and were
analyzed by NMR spectroscopy as the mixtures.
Trimethyl 3ꢀbenzylcyclopropaneꢀ1,1,2ꢀtricarboxylate (10a),
a 3.4 : 1 mixture of E and Z isomers. Total yield 89 mg (49%),
colorless oil. The isomers were partially resolved. E isomer was
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1
isolated pure. E Isomer. H NMR (400.1 MHz, CDCl ), δ: 2.68
3
3
3
(
3
dt, 1 H, CH(3), J = 7.6 Hz, J = 7.2 Hz); 2.75 (d, 1 H, CH(2),
J = 7.2 Hz); 2.82 (dd, 1 H, CH (1´)ꢀa, J = 15.4 Hz, J =
7.6 Hz); 2.94 (dd, 1 H, CH (1´)ꢀb, J = 15.4 Hz, J = 7.2 Hz);
2
3
2
2
3
=
2
3
5
3
5
2
.68 (s, 6 H, 2 CO Me); 3.74 (s, 3 H, CO Me); 7.17—7.34 (m,
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2
2
H, Ph). 1 C NMR (100.6 MHz, CDCl ), δ: 31.9 (CH (1´)),
3
3
2
2.7 and 32.8 (CH(2) and CH(3)), 42.2 (C(1)), 52.5, 53.0 and
3.1 (3 OMe), 126.6 (C(p)), 128.2 and 128.7 (2 C(o) and
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(
[
(
ESI). Found: m/z 329.0990. C16H18O . Calculated: 329.0996
M + Na] . Z Isomer. H NMR (400.1 MHz, CDCl ), δ: 2.21
ddd, 1 H, CH(3), J = 9.7 Hz, J = 9.4 Hz, J = 5.4 Hz); 2.67
6
+
1
3
3
3
3
3
(
d, 1 H, CH(2), J = 9.7 Hz); 3.12 (dd, 1 H, CH (1´)ꢀa,
J = 15.5 Hz, J = 9.4 Hz); 3.31 (dd, 1 H, CH (1´)ꢀb, J = 15.5 Hz,
J = 5.4 Hz); 3.70, 3.76, and 3.80 (all s, 3 H each, 3 CO Me);
2
2
3
2
2
3
2
1
3
7
2
5
.17—7.33 (m, 5 H, Ph). C NMR (100.6 MHz, CDCl ), δ:
3
9.3 (CH (1´)), 30.4 (CH(2)), 33.7 (CH(3)), 39.5 (C(1)), 52.2,
2
2.7, and 53.4 (3 OMe), 126.4 (C(p)), 128.5, and 128.6 (2 C(o)
and 2 C(m)), 140.1 (C(ipso)), 165.6, 168.9, and 169.5 (3 COO).
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1
Yield 47 mg (26%), colorless oil. H NMR (400.1 MHz,
CDCl ), δ: 3.43 and 3.72 (both s, 2 H each, 2 CH ); 3.63, 3.77,
3
2

Reactions of diazo esters with DꢀA cyclopropanes
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Received November 2, 2017;
in revised form December 5, 2017;
accepted December 8, 2017