Electrochemical transformation of malononitrile and carbonyl compounds into functionally substituted cyclopropanes: Electrocatalytic variant of the Wideqvist reaction

Article abstract of DOI:10.1016/S0040-4020(00)00195-2

Electrolysis of malononitrile and carbonyl compounds in the presence of alkali metal halides in an undivided cell results in the formation of substituted 1,1,2,2-tetracyanocyclopropanes in 60-90% yield. This electrocatalytic variant of the Wideqvist reaction using malononitrile instead of bromomalonitrile was successfully performed. Electrocatalytic transformation of substituted 1,1,2,2-tetracyanocyclopropanes in methanol or ethanol in an undivided cell leads to substituted 2-amino-4,4-dialkoxy-1,5- dicyano-3-azabicyclo[3.1.0]hex-2-enes in 70-95% yields after 0.05-0.10 F/mol of electricity has been passed. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00195-2

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 3063±3069
Electrochemical Transformation of Malononitrile and Carbonyl
Compounds into Functionally Substituted Cyclopropanes:
Electrocatalytic Variant of the Wideqvist Reaction
*
Michail N. Elinson, Sergey K. Feducovich, Tatiana L. Lizunova and Gennady I. Nikishin
N.D. Zelinsky Institute of Organic Chemistry, Leninsky prospect 47, 117913 Moscow B-334, Russia
Received 10 December 1999; revised 18 February 2000; accepted 2 March 2000
AbstractÐElectrolysis of malononitrile and carbonyl compounds in the presence of alkali metal halides in an undivided cell results in the
formation of substituted 1,1,2,2-tetracyanocyclopropanes in 60±90% yield. This electrocatalytic variant of the Wideqvist reaction using
malononitrile instead of bromomalonitrile was successfully performed. Electrocatalytic transformation of substituted 1,1,2,2-tetracyano-
cyclopropanes in methanol or ethanol in an undivided cell leads to substituted 2-amino-4,4-dialkoxy-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-
enes in 70±95% yields after 0.05±0.10 F/mol of electricity has been passed. q 2000 Elsevier Science Ltd. All rights reserved.
Malononitrile is one of the most famous and useful reagents
for the synthesis of heterocyclic compounds, pharma-
ceuticals, pesticides, fungicides, solvatochromic dyes, and
charge-transfer salts. The unique reactivity of this
compound has led to its widespread application in organic
chemistry, as well as or even more than other CH acidsÐ
malonate and cyanoacetic esters.
metal halides, we have carried out the electrochemical trans-
formation of cyanoacetic ester and aldehydes into 3-substi-
tuted 1,2-dicyanocyclopropane-1,2-dicarboxylates10 as well
as malonitrile and ketones into substituted 1,1,2,2-tetra-
cyanocyclopropanes.11 The present paper is devoted to a
detailed study of the co-electrolysis of malononitrile and
carbonyl compounds in order to estimate the scope and
limitations of the synthetic utility of this process.
Nevertheless, little is known about the electrochemistry of
malononitrile. Although the ®rst electrochemical oxidation
of malonate anion was performed in the 19th century,1
electrooxidation, electroreduction, or any other electro-
chemical transformations of malononitrile are not
mentioned in books or reviews of electroorganic
chemistry,2±5 nor in reviews dealing with the application
of malononitrile in organic synthesis.6,7 To our knowledge,
apart from the work of our research group, there is only one
publication which is concerned with this problem and
describes the electrochemical anodic arylation of malono-
nitrile.8
Electrolysis of malononitrile 1 in acetone in the presence of
alkali metal halides as mediators was carried out in an undi-
vided cell with a Pt-anode and an Fe-cathode under constant
current density. Under these conditions, malononitrile and
acetone were transformed into 3,3-dimethyl-1,1,2,2-tetra-
cyanocyclopropane 3a and isopropylidenemalononitrile 4a
(Table 1, Scheme 1).
It has been found that bromides are more effective mediators
than iodides. With sodium iodide as mediator, the yield of
cyclopropane 3a decreased by 30% and the main route of
the process in this case became the formation of alkene 4a.
The reaction can also be accomplished as co-electrolysis of
In the last few years, mediators were widely used for
the electrooxidation and electroreduction of organic
compounds.5 Among a variety of mediators, the redox
system halide anionÐhalogen is one of the most useful
from the viewpoint of organic synthesis and large-scale
processes.9
Recently, in the course of our study on the electrochemical
oxidation of organic compounds in the presence of alkali
Keywords: electrochemical reaction; catalysis; cyclopropanes; ketones.
* Corresponding author. Tel.: 17-095-938-35-42; fax: 17-095-135-58-
23; e-mail: elinson@cacr.ioc.ac.ru
Scheme 1.
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00195-2

3064
M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
Table 1. Electrochemical reaction of malononitrile with acetone (30 mmol of 1, 8 mmol of mediator, Pt-anode, Fe-cathode, current density 200 mA/cm2, 208C,
electricity passed 1 F/mol of 1)
Mediator
(electrolyte)
Acetone
(ml)
Ethanol
(ml)
Conversion
of 1 [%]
Yield of 3a
Yield of 4a
Substance yield (%)a
Current yield (%)
Substance yield (%)b
Current yield (%)
NaI
20
20
20
10
5
3
5
5
±
±
±
10
15
17
15c
15d
83
84
81
95
98
100
99
84
18
48
45
61
72
56
46
14
15
40
36
58
71
56
46
12
42
35
31
29
18
15
27
35
35
29
25
28
18
15
27
29
NaBr
LiBr
NaBr
NaBr
NaBr
NaBr
NaBr
a Isolated yields, based on 1 consumed.
b Determined by NMR spectroscopy.
c MeOH as a co-solvent.
d MeCN as a co-solvent.
The similar electrolysis of malononitrile in the presence of
ketones 2b±i was carried out under the same conditions,
which were optimised for the transformation of malono-
nitrile and acetone into cyclopropane 3a (Table 2, Scheme 2).
Surprisingly, under the same conditions, the reaction of
malononitrile and cyclohexanone led to 2-amino-1,5-
dicyano-4,4-diethoxy-6,6-pentamethylene-3-azabicyclo[3.1.0]-
hex-2-ene 5a in 62% yield (Scheme 3).
The electrolysis of malononitrile in the presence of alde-
hydes also results in the formation of 1,1,2,2-tetracyano-
cyclopropanes (Table 3, Scheme 4).
Scheme 2.
malonitrile 1 and acetone in ethanol, methanol, or aceto-
nitrile as a solvent. Ethanol was found to be the optimal
solvent. For reaction carried out in ethanol, the yield of 3a
depends on the concentration of acetone in the reaction
mixture. The optimum yield of 3a was achieved when
25% by volume concentration of acetone was used.
In the case of aldehydes it is not necessary to use an excess
of the carbonyl compound. Decreasing the temperature of
electrolysis from 20 to 08C ensures the formation of 6a±h in
high yields. Further decreasing the temperature or using an
excess of aldehyde in this reaction leads to the formation of
alkylidenemalononitriles RCHvC(CN)2 in substantial
yields (up to 40% at 2208C).
Table 2. Electrochemical reactions of malononitrile with ketones (30 mmol
of 1, 5 ml of ketone, 8 mmol of NaBr in 15 ml of EtOH, Pt-anode, Fe-
cathode, current density 200 mA/cm2, 208C, electricity passed 1.2 F/mol
of ketone)
Discussion
Ketone
R1
R2
Cyclopropanes 3b±i
Taking into consideration the above results, the following
general mechanism of the electrochemical transformation of
malononitrile and carbonyl compounds into substituted
1,1,2,2-tetracyanocyclopropanes is suggested.
Substance yield (%)a Current yield (%)
2b
2c
2d
2e
2f
2g
2h
2i
Me
Me
Me
Me
Pr
Et
Pr
91
75
71
70
32
86
60
25
76
63
59
58
27
72
50
21
Bu
(CH2)5Me
Pr
The reactions at the electrodes, which take place during the
process, are shown below:
(CH2)4
(CH2)6
Me
anode :
2Hal2 2 2e ! Hal2
Hal ˆ Br; I
Ph
a Isolated yields.
ꢀ
cathode :
2CH2ꢀCN†2 1 2e ! CHꢀCN†2 1 H2
Scheme 3.

M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
3065
cyclopropane:
2
ꢀ
CHꢀCN†2 1 Hal2 ! CHꢀHal†ꢀCN†2 1 Hal
ꢀ1†
ꢀ2†
CHꢀHal†ꢀCN†2 1 HO2 ! CHalꢀCN†2 1 H2O
ꢀ
ꢀ3†
Scheme 4.
The formation of iodine or bromine at the anode is a well-
known process and the corresponding colour is observed
when the electrolysis is conducted without stirring the reac-
tion mixture.
Sodium bromide is more effective as a mediator for the
above process than sodium iodide. This result is directly
related to the fact that intermediate bromomalononitrile is
a stronger CH acid than iodomalononitrile and thus the stage
of proton abstraction with the formation of halogenomalo-
nonitrile anion (2) is faster in the case of sodium bromide as
a mediator.
The alternative reaction on the cathode when ethanol or
methanol is used as solvent or co-solvent could be the
formation of alkoxide ion on the cathode. However, in
this case, the following reaction in solution between
alkoxide ion and malononitrile should lead to the formation
of malononitrile ion as the general result of the cathodic
process.
The maximum yield of 3a was achieved under the con-
ditions with 25% by volume concentration of acetone.
When the higher concentration of acetone is used, the larger
quantity of isopropylidenemalononitrile 4a is obtained at
the end of the electrolysis.
The reaction of malononitrile anion with carbonyl
compounds leading to alkylidenemalonates has been studied
earlier:12
Tetracyanocyclopropanes 3f and 3i were obtained in lower
yields (32 and 25%, respectively) than those in all other
cases. This is related to a lower rate of the reaction of the
corresponding ketones 2f and 2i with malononitrile, and in
these two cases a side reaction is the oligomerisation of
malononitrile under the conditions of the electrolysis.
1
2
1
2
2
ꢀ
CHꢀCN†2 1 R R CHvO ! R R CvCꢀCN†2 1 HO
The bromination of malononitrile anion by halogen
generated at the anode, the formation of halogenomalono-
nitrile anion, followed by addition of the latter to alkylide-
nemalonate gives rise to substituted 1,1,2,2-tetracyano-
However, there is a possibility of increasing the yield of 3f
and 3i by performing the electrolysis of alkylidenemalo-
nates in the presence of malononitrile (Scheme 5).
Table 3. Electrochemical reactions of malononitrile with aldehydes
(20 mmol of 1, 20 mmol of aldehyde, 8 mmol of NaBr in 20 ml of EtOH,
Pt-anode, Fe-cathode, current density 100 mA/cm2, 08C)
The results in Table 4 also con®rm the suggested mecha-
nism.
Aldehyde
R1
Electricity passed
(F/mol)
Cyclopropanes 7a±h:
substance yield, (%)a
In the case of the electrochemical reaction of cyclohexanone
with malononitrile in EtOH, the corresponding tetracyano-
cyclopropane is very easily attacked by ethoxide anion and
affords the further transformation into bicyclic pyrroline 5a.
6a
6b
6c
6d
6e
6f
H
Me
Pr
1.8
1.2
1.4
1.2
1.8
1.7
1.2
1.2
60
65
76
78
95
76
96
90
Ph
It has been found that the above process is a general reaction
for tetracyanocyclopropanes (Scheme 6).
2-ClC6H4
2-BrC6H4
4-IC6H4
6g
6h
Table 4. Electrochemical reactions of malononitrile with alkylidene-
malononitriles (20 mmol of 1, 20 mmol of alkylidenemalononitrile 4,
8 mmol of NaBr in 20 ml of EtOH, Pt-anode, Fe-cathode, current density
200 mA/cm2, 208C, electricity passed 1.2 F/mol)
3-MeOC6H4
a Isolated yields.
Alkylidene-
malononitrile
R1
R2
Cyclopropanes 3
Substance
yield (%)a
Current
yield (%)
4a
4e
4f
4i
Me
Me
Pr
Me
Me(CH2)5
Pr
Ph
82
78
75
62
68
65
63
52
Me
a Isolated yields.
Scheme 5.

3066
M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
Scheme 6.
the regeneration of R3O2 anion at the last stage, which
continues the chain reaction process by the interaction
with the next molecule of tetracyanocyclopropane.
Table 5. Electrocatalytic transformation of 1,1,2,2-tetracyanocyclopro-
panes into 2-amino-4,4-dialkoxy-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-
enes (6 mmol of substrate, 8 mmol of NaBr in 20 ml of R3OH, Pt-anode,
Fe-cathode, current density 200 mA/cm2, 208C, reaction time 1±2 min)
Substrate
R1
R2
R3
Electricity
Product,
The only analogue of this reaction known to us is that
between phthalonitrile and EtONa, which gives isoindole
derivative 8.13
passed (F/mol) yield (%)a
3a
3a
3b
6c
3c
6d
3g
Me
Me
Et
Pr
Pr
Ph
Me
Me
Me
H
Me
H
Me
Et
Me
Me
Me
Et
0.1
0.1
0.05
0.1
0.1
0.1
0.1
5b, 94
5c, 95
5d, 93
5e, 80
5f, 71
5g, 81
5h, 95
(CH2)4
Me
a Isolated yields.
The R3O2 ion generated at cathode reacts with 3a±c,g or
6c,d forming 5b±h; complete conversion of the substrate
was achieved when only 0.05±0.01 F/mol of electricity was
passed (current yield 700±1800%).
Thus, the simple electrocatalytic system can produce
under mild conditions direct `one-pot' transformations of
malononitrile and carbonyl compounds into the correspond-
ing substituted tetracyanocyclopropanes in high yields.
Under similar electrocatalytic conditions, tetracyanocyclo-
propanes were transformed into corresponding bicyclic
pyrrolines 5b±h. These processes are economical and
convenient methods for the electrochemical synthesis of
tetracyanocyclopropanes and bicyclic pyrrolines, using
only inexpensive reagents and simple equipment; they are
easily carried out in an undivided cell.
The suggested mechanism of the reaction involves the steps
shown in Scheme 7.
The formation of 5b±h as a result of the chain electro-
catalytic mechanism shown in Scheme 7 takes place by
successive addition of two R3OH molecules to the initial
tetracyanocyclopropane initiated by R3O2 ion and includes
Scheme 7.

M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
3067
Experimental
1,1,2,2-Tetracyano-3,3-tetramethylenecyclopropane (3g).15,17
1
Mp 250±2518C (Lit.15 240±2438C), H NMR (CD3OD): d
GLC analyses were carried out on an LKhM-80 chromatograph
with a ¯ame-ionisation detector, 3 m£3 mm glass columns
packed with 5% OV-17 on Inerton (0.16±0.20 mm) or 10%
FFAP on Chromaton N-Super (0.13±0.16 mm), respec-
1.10 (m, 4H, CH2) 1.72 (m, 4H, CH2). 13C NMR (acetone-d6):
d 27.12 t, 27.91 s, 33.23 t, 51.11 s 110.50 s. Anal. calcd for
C11H8N4: C, 67.35; H, 4.08; N 28.57. Found: C, 67.56; H,
4.02; N 28.82.
tively. H and 13C NMR spectra were recorded in CDCl3
1
on a Bruker WM-250 (250 MHz) or a Bruker AM-300
(300 MHz) spectrometer, with tetramethylsilane (TMS) as
the internal standard.
1,1,2,2-Tetracyano-3,3-hexamethylenecyclopropane (3h).
1
Mp 170±1718C, H NMR (CDCl3): d 1.80±2.00 (m, 8H,
CH2), 2.17 (m, 4H, CH2). 13C NMR (DMSO-d6): d 22.71 t,
27.43 t, 28.11 s, 32.23 t, 47.42 s 119.91 s. Anal. calcd for
C13H12N4: C, 69.64; H, 5.36; N 25.01. Found: C, 69.93; H,
5.17; N 24.97.
General electrolysis procedure for the reaction of
malononitrile with ketones
1,1,2,2-Tetracyano-3-methyl-3-phenylcyclopropane (3i).
1
A solution of 1 (30 mmol), sodium halide (8 mmol), and
ketone (3±5 ml) in 15 ml of ethanol was electrolysed in
an undivided cell equipped with a Pt-anode and an
Fe-cathode at 208C under constant current density
200 mA/cm2 until the quantity of the electricity indicated
in Tables 1 and 2 (1 or 1.2 F/mol) was passed. The solvent
and an excess of ketone were removed, and the residue was
extracted with ethyl acetate, washed with water, and dried
with Na2SO4. Ethyl acetate was then removed, and the
residue was crystallised from acetone±hexane.
Mp 254±2558C (Lit.16 2258C), H NMR (acetone-d6): d
1.91 (s, 3H, CH3), 7.40±7.80 (m, 5H, C6H5). 13C NMR
(DMSO-d6): d 23.41 q, 27.93 s, 47.62 s 109.93 s, 110.21
s, 128.92 d, 129.31 d, 129.83 d, 132.51 s.
Isopropylidene malonitrile (4a). The compound 4a was
isolated by distillation of the rest of reaction mixture of
the electrolysis of malononitrile in acetone in the presence
of NaI as mediator (Table 1) after isolation of 3a in 18%
yield, bp 106±1088C (21 Torr), n2D5 1.4663 (Lit.15 n2D3
1
1,1,2,2-Tetracyano-3,3-dimethylcyclopropane (3a).14,15
1.4670), H NMR (CDCl3): d 2.23 s.
1
Mp 210±2118C (Lit.14 209.5±2108C), H NMR (DMSO-
d6): d 1.57 s. 13C NMR (acetone-d6): d 19.82 q, 27.91 s,
41.52 s, 110.63 s.
2-Amino-1,5-dicyano-4,4-diethoxy-6,6-pentamethylene-
3-azabicyclo[3.1.0]hex-2-ene
5a.
Mp
155±1578C
(decomp.), 1H NMR (DMSO-d6): d 1.15 (t, 6H, CH2),
1.40±1.95 (m, 10H, CH2), 3.40±3.75 (m, 4H, CH2O), 7.40
(s, 2H, NH2). 13C NMR (DMSO-d6): d 14.81 q, 15.23 q,
23.92 t, 24.41 t, 24.72 t, 25.63 t, 31.81 t, 39.32 s, 41.81 s,
44.82 s, 57.03 t, 59.21 t, 113.52 s, 114.43 s, 116.21 s, 156.52
s. Anal. calcd for C16H22N4O2: C, 63.58; H, 7.28; N 18.54.
Found: C, 63.45; H, 7.14; N 18.38.
1,1,2,2-Tetracyano-3-ethyl-3-methylcyclopropane (3b).15,16
Mp 208±2098C (Lit.15 204±2068C), 1H NMR (acetone-d6):
d 1.32 (t, 3H, CH3), 1.73 (s, 3H, CH3), 2.15 (q, 2H, CH2).
13C NMR (DMSO-d6): d 8.91 q, 15.93 q, 26.42 t, 27.43 s,
44.51 s, 110.12 s.
1,1,2,2-Tetracyano-3-methyl-3-propylcyclopropane (3c).15,17
Mp 170±1718C (Lit.17 167.5±1688C), 1H NMR (DMSO-d6):
d 0.95 (t, 3H, CH3), 1.60 (s, 3H, CH3), 1.60±1.90 (m, 4H,
CH2). 13C NMR (acetone-d6): d 14.01 q, 17.13 q, 19.11 t,
27.83 s, 39.91 t, 44.52 s, 110.31 s.
General electrolysis procedure for the reaction of
malononitrile with aldehydes
A solution of 1 (20 mmol), aldehyde (20 mmol), and sodium
bromide (8 mmol) in 20 ml of ethanol was electrolysed in an
undivided cell equipped with a Pt-anode and an Fe-cathode
at 08C under constant current density 100 mA/cm2 until the
quantity of the electricity indicated in Table 3 was passed.
The solvent was removed, and the residue was extracted
with ethyl acetate, washed with water, and dried with
Na2SO4. Ethyl acetate was removed, and the residue was
crystallised from ethyl acetate±hexane.
3-Butyl-1,1,2,2-tetracyano-3-methylcyclopropane (3d).
Mp 130±1328C, 1H NMR (acetone-d6): d 0.95 (t, 3H,
CH3), 1.45 (m, 2H, CH2), 1.65 (m, 2H, CH2), 1.81 (s, 3H,
CH3), 2.15 (t, 2H, CH2). 13C NMR (acetone-d6): d 13.92 q,
17.21 q, 23.13 t, 27.72 t, 28.01 s, 33.94 t, 44.71 s, 110.43 s.
Anal. calcd for C12H12N4: C, 67.92; H, 5.66; N 26.42.
Found: C, 67.86; H, 5.79; N 26.67.
1,1,2,2-Tetracyano-3-hexyl-3-methylcyclopropane (3e).
1,1,2,2-Tetracyanocyclopropane (7a).18,19 Mp 230±2328C
(decomp.) [Lit.18 223±2258C (decomp.)], 1H NMR (DMSO-
d6): d 3.55 s. 13C NMR (DMSO-d6): d 17.71 s, 28.83 t,
110.91 s.
1
Mp 78±808C (Lit.16 80±80.58C), H NMR (acetone-d6): d
0.90 (t, 3H, CH3), 1.40±1.65 (m, 8H, CH2), 1.75 (s, 3H,
CH3), 2.11 (t, 2H, CH2). 13C NMR (DMSO-d6): d 13.61 q,
17.43 q, 21.72 t, 24.04 t, 27.32 s, 28.31 t, 30.72 t, 32.71 t,
43.72 s, 109.72 s, 109.81 s.
1,1,2,2-Tetracyano-3-methylcyclopropane (7b).16,20 Mp
1
189±1918C (Lit.20 1928C), H NMR (DMSO-d6): d 1.49
1,1,2,2-Tetracyano-3,3-dipropylcyclopropane (3f). Mp
(d, 3H, CH3), 3.66 (q, 1H, CH). 13C NMR (DMSO-d6): d
11.62 q, 22.81 s, 35.93 d, 109.52 s, 110.91 s.
1
122±1238C, H NMR (acetone-d6): d 0.95 (t, 6H, CH3),
1.50±1.85 (m, 8H, CH2). 13C NMR (acetone-d6): d 13.91
q, 19.03 t, 27.61 s, 32.83 t, 47.52 s, 110.41 s. Anal. calcd for
C13H14N4: C, 69.03; H, 6.19; N 24.78. Found: C, 68.78; H,
6.07; N 25.01.
1,1,2,2-Tetracyano-3-propylcyclopropane (7c).17,20 Mp
1
136±1388C (Lit.20 1318C), H NMR (DMSO-d6): d 0.95
(t, 3H, CH3), 1.58 (m, 2H, CH2), 1.72 (m, 2H, CH2), 3.86

3068
M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
(t, 1H, CH). 13C NMR (DMSO-d6): d 13.21 q, 19.33 t, 28.62
t, 22.11 s, 39.23 d, 109.41 s, 110.73 s.
pyrrolines were crystallised directly from the reaction
mixture and were then ®ltered off. In other cases, the solvent
was removed, and the residue was extracted with ethyl ace-
tate, washed with water, and dried with Na2SO4. Ethyl ace-
tate was removed, and the residue was crystallised from
acetone±hexane.
1,1,2,2-Tetracyano-3-phenylcyclopropane (7d).16,21 Mp
1
229±2318C (Lit.21 227±2308C), H NMR (DMSO-d6): d
5.10 (s, 1H, CH), 7.48±7.80 (m, 5H, C6H5). 13C NMR
(DMSO-d6): d 23.02 s, 41.93 d, 109.32 s, 110.91 s,
126.81 d, 128.93 d, 129.52 d, 130.01 s.
2-Amino-1,5-dicyano-4,4-dimethoxy-6,6-dimethyl-3-aza-
bicyclo[3.1.0]hex-2-ene 5b. Mp 170±1728C (decomp.), 1H
NMR (DMSO-d6): d 1.27 (s, 3H, CH3), 1.51 (s, 3H, CH3),
3.24 (s, 3H, OCH3), 3.26 (s, 3H, OCH3), 7.30 (s, 2H, NH2).
13C NMR (DMSO-d6): d 15.31 q, 21.53 q, 39.22 s, 40.21 s,
40.52 s, 48.81 q, 51.32 q, 113.31 s, 114.72 s, 117.11 s,
157.33 s. Anal. calcd for C11H14N4O2: C, 56.41; H, 5.98;
N, 23.93. Found: C, 56.65; H, 5.91; N, 24.12.
3-(2-Chlorophenyl)-1,1,2,2-tetracyanocyclopropane (7e).
1
Mp 246±2478C (decomp.) (Lit.21 246±2488C), H NMR
(DMSO-d6): d 5.22 (s, 1H, CH), 7.50±8.15 (m, 4H, Ar).
13C NMR (DMSO-d6): d 23.52 s, 40.41 d, 109.24 s,
110.51 s, 125.02 d, 127.81 d, 130.13 d, 131.23 d, 132.11
s, 134.13 s.
3-(2-Bromophenyl)-1,1,2,2-tetracyanocyclopropane (7f).
2-Amino-1,5-dicyano-4,4-diethoxy-6,6-dimethyl-3-aza-
bicyclo[3.1.0]hex-2-ene 5c. Mp 130±1328C (decomp.), H
1
1
Mp 248±2498C (decomp.) (Lit.21 249±2528C), H NMR
(DMSO-d6): d 5.48 (s, 1H, CH), 7.40±8.10 (m, 4H, Ar).
13C NMR (DMSO-d6): d 23.51 s, 40.42 d, 109.21 s,
110.52 s, 125.03 d, 127.82 d, 130.11 d, 131.22 d, 132.13
s, 134.01 s.
NMR (DMSO-d6): d 1.05±1.15 (t, 6H, CH3), 1.25 (s, 3H,
CH3), 1.50 (s, 3H, CH3), 3.40±3.70 (m, 4H, OCH2), 7.25 (s,
2H, NH2). 13C NMR (DMSO-d6): d 14.82 q, 15.21 q, 15.53
q, 21.51 q, 39.03 s, 40.11 s, 41.02 s, 56.91 t, 59.32 t, 113.41
s, 114.73 s, 116.42 s, 157.01 s. Anal. calcd for C13H18N4O2:
C, 59.54; H, 6.87; N, 21.37. Found: C, 59.37; H, 6.98; N,
21.19.
1,1,2,2-Tetracyano-3-(4-iodophenyl)cyclopropane (7g).
1
Mp 227±2298C (decomp.), H NMR (DMSO-d6): d 5.28
(s, 1H, CH), 7.65 (d, 2H, Ar), 7.89 (d, 2H, Ar). 13C NMR
(DMSO-d6): d 23.11 s, 41.32 d, 97.53 s, 109.41 s, 110.82 s,
126.73 d, 131.72 d, 137.71 s. Anal. calcd for C13H5N4I: C,
45.35; H, 1.45; N, 16.28; I, 36.92. Found: C, 45.71; H, 1.54;
N, 16.36; I, 36.85.
2-Amino-1,5-dicyano-6-ethyl-4,4-dimethoxy-6-methyl-3-
azabicyclo[3.1.0]hex-2-ene 5d (mixture of two isomers).
1
Mp 153±1558C (decomp.), H NMR (DMSO-d6): d 0.97
and 1.13 (t, 6H, CH3), 1.24 and 1.48 (s, 3H, CH3), 1.75
(m, 4H, CH2), 3.25 and 3.26 (s, 6H, OCH3), 7.35 (s, 2H,
NH2). 13C NMR (DMSO-d6): d 9.42 q, 10.11 q, 11.63 q,
16.32 q, 21.33 t, 28.51 t, 40.01 s, 40.13 s, 41.82 s, 43.41 s,
43.62 s, 48.81 q, 51.32 q, 113.21 s, 113.42 s, 114.41 s,
114.43 s, 116.91 s, 116.92 s, 157.03 s, 157.31 s. Anal.
calcd for C12H16N4O2: C, 58.06; H, 6.45; N, 22.58. Found:
C, 58.28; H, 6.54; N, 22.32.
1,1,2,2-Tetracyano-3-(3-methoxyphenyl)cyclopropane
(7h). Mp 227±2298C (decomp.), H NMR (DMSO-d6): d
1
3.76 (s, 3H, OCH3), 5.28 (s, 1H, CH), 6.90±7.70 (m, 4H,
Ar). 13C NMR (DMSO-d6): d 23.12 s, 41.72 d, 55.53 q,
109.41 s, 110.92 s, 115.13 s, 115.82 d, 121.41 d, 128.13 d,
130.11 d, 149.43 s. Anal. calcd for C14H8N4O: C, 67.74; H,
3.23; N, 22.58. Found: C, 67.89; H, 3.14; N, 22.63.
2-Amino-1,5-dicyano-4,4-dimethoxy-6-propyl-3-azabi-
cyclo[3.1.0]hex-2-ene 5e. Mp 187±1898C (decomp.), H
1
General electrolysis procedure for the reaction of
malononitrile with alkylidenemalononitriles
NMR (DMSO-d6): d 0.95 (t, 3H, CH3), 1.55 (m, 2H,
CH3), 1.74 (m, 2H, CH2), 3.24 (s, 3H, OCH3), 3.27 (s, 3H,
OCH3), 3.83 (t, 1H, CH), 7.32 (s, 2H, NH2). 13C NMR
(DMSO-d6): d 14.11 q, 18.82 t, 19,13 t, 39.21 s, 41.13 s,
41.82 d, 49.31 q, 51.92 q, 112.71 s, 112.73 s, 117.72 s,
157.63 s. Anal. calcd for C12H16N4O2: C, 58.06; H, 6.45;
N, 22.58. Found: C, 57.95; H, 6.37; N, 22.67.
A
solution of 1 (20 mmol), alkylidenemalononitrile
(20 mmol), and sodium bromide (8 mmol) in 20 ml of
ethanol was electrolysed in an undivided cell equipped
with a Pt-anode and an Fe-cathode at 208C under constant
current density 200 mA/cm2 until the quantity of the elec-
tricity indicated in Table 4 was passed (1.2 F/mol). The
solvent was removed, and the residue was extracted with
ethyl acetate, washed with water, and dried with Na2SO4.
Ethyl acetate was then removed, and the residue was
crystallised from acetone±hexane.
2-Amino-1,5-dicyano-4,4-dimethoxy-6-methyl-6-propyl-
3-azabicyclo[3.1.0]hex-2-ene 5f (mixture of two isomers).
1
Mp 127±1298C (decomp.), H NMR (DMSO-d6): d 0.92
and 0.96 (t, 3H, CH3), 1.21 and 1.49 (s, 3H, CH3), 1.45±
1.85 (m, 4H, CH3), 3.24 and 3.25 (s, 6H, OCH3), 7.29 (s, 2H,
NH2). 13C NMR (DMSO-d6): d 12.31 q, 14.01 q, 14.22 q,
14.41 q, 18.62 t, 18.71 t, 19.03 t, 19.11 t, 30.12 s, 40.03 s,
40.11 s, 40.82 s, 42.21 s, 42.44 s, 42.61 s, 48.82 q, 49.31 q,
51.21 q, 51.53 q, 113.41 s, 113.43 s, 114.82 s, 114.84 s,
117.21 s, 117.23 s, 157.22 s, 157.23 s. Anal. calcd for
C13H18N4O2: C, 59.54; H, 6.87; N, 21.37. Found: C,
59.31; H, 6.80; N, 21.45.
General electrolysis procedure for the conversion of
tetracyanocyclopropanes into substituted bicyclic
pyrrolines
A solution of tetracyanocyclopropane (6 mmol) and sodium
bromide or sodium acetate (8 mmol) in 20 ml of alcohol was
electrolysed in an undivided cell equipped with a Pt-anode
and an Fe-cathode at 208C under constant current density
100 mA/cm2 until the quantity of the electricity indicated in
Table 5 was passed (0.05±0.10 F/mol). Usually bicyclic
2-Amino-1,5-dicyano-4,4-diethoxy-6-phenyl-3-azabicyclo-
[3.1.0]hex-2-ene 5g. Mp 247±2498C (decomp.), H NMR
1

M. N. Elinson et al. / Tetrahedron 56 (2000) 3063±3069
3069
È
3. Shafer, H. J. Angew. Chem., Int. Ed. Engl. 1981, 20, 911.
(DMSO-d6): d 1.07 and 1.11 (t, 6H, CH3), 3.50 and 3.70 (m,
4H, CH2O), 5.25 (s, 1H, CH), 7.29 (s, 2H, NH2), 7.70±7.80
(m, 5H, C6H5). 13C NMR (DMSO-d6): d 15.02 q, 15.21 q,
35.43 s, 38.21 s, 41.42 s, 57.73 t, 59.32 t, 112.31 s, 113.52 s,
118.14 s, 128.80 d, 128.83 d, 129.06 d, 129.73 s, 159.01 s.
Anal. calcd for C17H18N4O2: C, 65.81; H, 5.81; N, 18.06.
Found: C, 65.74; H, 5.75; N, 18.27.
4. Shono, T. Electroorganic Chemistry as a New Tool in Organic
Synthesis. In Reactivity and Structure: Concepts in Organic
Chemistry; Springer-Verlag: Berlin, 1984; Vol. 20.
5. Novel Trends in Electroorganic Synthesis, Torii, S., Ed.;
Springer-Verlag: Berlin, 1998.
6. Freeman, F. Chem. Rev. 1969, 69, 591.
7. Fatiadi, A. J. Synthesis 1978, 165.
2-Amino-1,5-dicyano-4,4-dimethoxy-6,6-tetramethylene-
8. Ismail, M. T. J. Appl. Electrochem. 1987, 17, 881.
9. Shono, T. Tetrahedron 1984, 40, 811.
3-azabicyclo[3.1.0]hex-2-ene
5h.
Mp
215±2178C
(decomp.), 1H NMR (DMSO-d6): d 1.40±2.10 (m, 8H,
CH2), 3.24 (s, 3H, CH3O), 3.26 (s, 3H, CH3O), 7.32 (s,
2H, NH2). 13C NMR (DMSO-d6): d 27.54 t, 27.56 t, 32.31
t, 32.34 t, 39.13 s, 40.21 s, 40.72 s, 48.93 q, 51.52 q, 113.71
s, 113.72 s, 117.30 s, 157.31 s. Anal. calcd for C13H16N4O2:
C, 60.03; H, 6.15; N 21.54. Found: C, 60.15; H, 6.07; N
21.37.
10. Elinson, M. N.; Lizunova, T. L.; Ugrak, B. I.; Dekaprilevich,
M. O.; Nikishin, G. I.; Struchkov, Yu, T. Tetrahedron Lett. 1993,
34, 5795.
11. Nikishin, G. I.; Elinson, M. N.; Lizunova, T. L.; Ugrak, B. I.
Tetrahedron Lett. 1991, 32, 2655.
12. Patai, S.; Israeli, Y. J. Chem. Soc. 1960, 2025.
13. Baumann, F.; Bienert, B.; Rosch, G.; Vollmann, H.; Wolf, W.
Angew. Chem. 1956, 68, 133.
14. Ramberg, L.; Wideqvist, S. Arkiv. Kemi B 1941, 14 (N37), 13.
15. Hart, H.; Kim, Y. Ch. J. Org. Chem. 1966, 31, 2784.
16. Wideqvist, S. Arkiv. Kemi B 1945, 20 (N4), 8.
17. Hart, H.; Freeman, F. J. Org. Chem. 1963, 28, 1220.
18. Scribner, R. M.; Sausen, G. N.; Prichard, W. W. J. Org. Chem.
1960, 25, 1440.
Acknowledgements
The authors gratefully acknowledge the ®nancial support of
the Russian Foundation for Basic Research (Project No. 97-
03-33165a).
19. Huisgen, R.; Eichenauer, U.; Laughals, E.; Mitra, A.; Moran,
J. R. Chem. Ber. 1987, 120, 153.
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