Mendeleev Commun., 2009, 19, 324–325
Table 2 Direct transformation of olefins 1a–q and malononitrile 2 into
As compared to the earlier known method of the trans-
formation of alkylidenemalononitriles 1 and malononitrile 2
into substituted 1,1,2,2-tetracyanocyclopropanes 3 in the basic
alcohol solutions,13 this new method of the action of aqueous
bromine on alkylidenemalononitriles and malononitrile in
substituted 1,1,2,2-tetracyanocyclopropanes 3a–q by the action of bromine
a
in EtOH/water system.
R1
R2
b
Olefin
Product
Yield of 3 (%)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
a
b
c
d
e
H
H
H
H
H
H
H
H
H
H
H
Me
Me
Et
Ph
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
3q
96
95
98
96
95
94
91
90
96
94
93
63
60
55
93
95
91
EtOH–H O system results in the formation of 1,1,2,2-tetracyano-
4-MeC H4
4-MeOC H4
3-MeOC H4
2-MeOC H4
4-FC H4
4-ClC H4
3-ClC H4
3-BrC H4
4-NO C H
Pr
Me
Et
Et
2
6
cyclopropanes 3 in the yields being 10–25% higher, eliminates
the necessity to use 1.2 equiv. of EtONa as a base and the time
of this new cascade process is three times shorter (1 h instead
of 3 h). This sufficient yield increase is partly a result of notice-
ably lower solubility of 3-substituted 1,1,2,2-tetracyanocyclo-
6
6
6
f
6
g
h
i
j
k
l
m
n
o
p
q
6
6
propanes 3 in EtOH–H O mixtures in comparison with the pure
6
2
2
6
4
EtOH solutions.
Thus, the new cascade reaction was found, namely: the
formation of cyclopropanes from activated olefins and CH acids
by the direct action of the only bromine. The action of aqueous
bromine on the equal amounts of alkylidenemalononitriles and
(CH2)4
(CH2)
5
malononitrile in EtOH–H O solution results in the formation of
2
(CH2)6
3-substituted 1,1,2,2-tetracyanocyclopropanes in 55–98% yields.
a10 mmol of olefin 1, 10 mmol of malononitrile 2, 20 ml of EtOH, 50 ml of
The procedure utilises inexpensive reagents, it is easily carried out
and the work up is not complicated. 3-Substituted 1,1,2,2-tetra-
cyanocyclopropanes are crystallized directly from the reaction
mixture, consequently, the isolation includes only filtration and
b
0
.2 M Br2 in water (10 mmol), time of reaction 1 h. Yield of isolated
product.
6
0 °C had a little effect on 1,1,2,2-tetracyanocyclopropane 3a
formation.
Under the optimal conditions thus found, all other experi-
washing with 5% aqueous solution of Na SO and warm water.
2
3
This work was supported by the Russian Foundation for
Basic Research (project no. 09-03-00003a) and the Presidential
Scholarship Programme for the State Support of Leading Scientific
Schools of the Russian Federation (project no. 5022.2006.3).
ments were carried out (Table 2).
Under the conditions of Table 2, benzylidenemalononitriles
1a–j, propylidenemalononitrile 1k, and cycloalkylidenemalono-
nitriles 1o–q in the presence of malononitrile were directly
transformed into corresponding 1,1,2,2-tetracyanocyclopropanes
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R1
R2
R1
R2
CN
Br
NC
NC
NC
CN
CN
–
HBr
NC
CN
3
Scheme 2
Received: 17th April 2009; Com. 09/3324
–
325 –