Mendeleev Commun., 2002, 12(2), 63–64
Nucleophilic addition of secondary nitro compounds to acetylene
Boris F. Kukharev,* Valery K. Stankevich and Galina R. Klimenko
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk,
Russian Federation. Fax: +7 3952 39 6046; e-mail: admin@irioch.irk.ru
10.1070/MC2002v012n02ABEH001541
The products of C-vinylation were prepared in 52–65% yield by the reaction of secondary nitroalkanes with acetylene in DMSO–
KOH.
Mono- and polynitroalkanes can add to an activated triple carbon–
carbon bond under conditions of basic catalysis, for example, to
the esters of propiolic acid.1
It is well known that nucleophilic addition to acetylene is
facilitated in a ‘super-base’ DMSO–KOH medium.2
We found that 2-nitropropane 1a and nitrocyclohexane 1b
added to acetylene in DMSO–KOH to give corresponding C-
vinylation products 2a,b. The process proceeded at an initial
acetylene pressure of 14 atm and at 100 °C. The full conversion
of compounds 1a,b was reached in 4 h.†
alkanes to cause autocondensation under alkaline conditions, for
example, to methazonic acid and isooxazole derivatives.1(b),3
Terminal acetylenes, as well as acetylene, can successfully
react with secondary nitroalkane derivatives in DMSO–KOH.
Thus, the E- and Z-isomers of 1-(3-methyl-3-nitro-1-butenyl)-
benzene 5a,b were obtained by the reaction of 2-nitropropane
and phenylacetylene.‡
According to 1H NMR data, the amount of the E-isomer was
higher than that of the Z-isomer by a factor of 4.2. Moreover, the
1H NMR spectra of the reaction products exhibited no signals
due to 1-[1-(1-methyl-1-nitroethyl)vinyl]benzene 5c, which is the
product of the addition of 2-nitropropane to α-phenylacetylene.
R
R
C2H2
CH NO2
C
NO2
R
R
NO2
NO2
NO2
H
H
Ph
H
H
1a,b
2a,b
1a
1a
PhC CH
a R = Me
b R + R = (CH2)5
Ph
H
Ph
H
5c
5a
5b
Scheme 1
Scheme 3
1
The H NMR spectra of the reaction mixtures exhibited no
signals that could be assigned to the vinylation products of
either the acy-forms of nitro compounds 3a,b or oxymes 4a,b.
The formation of the above compounds results from the splitting
of nitro esters. Thus, under the given conditions, the process of
O-vinylation did not proceed.
The predominant formation of isomer 5a and the absence of
isomer 5c in the reaction mixture suggest that the reaction pro-
ceeds by a coordinated trans-nucleophilic addition mechanism.4
The nitronate ion3 [Me2C––N+(=O)O–
«
Me2C=N+O22–] served
as a nucleophile; it was formed by the alkaline deprotonation of
the nitroalkane.
R
R
R
R
R
R
O
O
C2H2
1a b
,
NO2
C
N
C
N
C
NOH
OH
O
3a b
,
4a b
,
Ph
Scheme 2
H
NO2
Our attempts to carry out the C-vinylation of nitro compounds
1a,b using benzene as a solvent were unsuccessful.
In the reactions of acetylene with nitromethane, nitroethane
and 1-nitropropane in DMSO–KOH, only resin-like products were
isolated. Probably, this was due to the ability of primary nitro-
Scheme 4
References
1 (a) V. V. Perecalin and A. S. Sopova, Nenasyshchennye nitrosoedineniya
(Unsaturated Nitro Compounds), Nauka, Moscow, 1966 (in Russian);
(b) S. S. Novikov, G. A. Shwekhgeimer, V. V. Sevostyanova and V. A.
Shlyapochnikov, Khimiya alifaticheskikh i alitsiklicheskikh nitrosoedi-
nenii (Chemistry of Aliphatic and Aliciclyc Nitro Compounds), Khimiya,
Moscow, 1974 (in Russian); (c) V. Grakauskas and K. Baum, J. Org.
Chem., 1969, 34, 3927.
2 B. A. Trofimov, Zh. Org. Khim., 1986, 22, 1991 [J. Org. Chem. USSR
(Engl. Transl.), 1986, 22, 1788].
3 P. G. Coombes, in Comprehensive Organic Chemistry. The Synthesis
and Reactions of Organic Compounds, eds. D. Barton and W. D. Ollis,
†
A mixture of compound 1a or 1b (10 g), powdered potassium hydroxide
(5 g) and DMSO (100 ml) was placed in a stainless steel 250 ml rotary
autoclave. The mixture was saturated with acetylene at 14 atm and heated
at 100 °C for 4 h. After cooling, the mixture was poured into 1 dm3 of
cold water and extracted with diethyl ether (3×100 ml). The combined
extracts were dried with anhydrous potassium carbonate, and the ether
was distilled in a vacuum to give nitroalkenes 2a,b.
2a: yield 52%, bp 71–72 °C (61 torr), nD20 1.4335, d420 0.9576. 1H NMR
3
(400 MHz, CDCl3) d: 1.68 (s, 6H, Me), 5.31 (d, 1H, cis-CH=C, Jcis
3
10.7 Hz), 5.35 (d, 1H, trans-CH=C, Jtrans 17.3 Hz), 6.18 (dd, 1H,
C–CH=C, 3Jcis 10.7 Hz, 3Jtrans 17.3 Hz). 13C NMR (100 MHz, CDCl3) d:
25.37 (Me), 87.78 (NC), 116.56 (=CH2), 138.12 (=CH). IR (neat, n/cm–1):
1530 (NO2), 1630 (C=C), 3085 (=CH2). Found (%): C, 52.24; H, 7.98;
N, 12.02. Calc. for C5H9NO2 (%): C, 52.16; H, 7.88; N, 12.17.
‡
A mixture of compound 1a (18.8 g), phenylacetylene (14 g), melted
potassium hydroxide (7.5 g) and 150 ml of DMSO was stirred at 100 °C
for 6 h. After cooling, the mixture was treated as described above; a
mixture of two nitro compounds 5a,b was isolated.
2b: yield 65%, bp 77–78 °C (4 torr), nD20 1.4818, d420 1.0336. 1H NMR
(400 MHz, CDCl3) d: 1.36–1.60 (m, 6H, C6H10), 1.84 (m, 2H, C6H10),
2.44 (m, 2H, C6H10), 5.32 (d, 1H, cis-CH=C, 3Jcis 10.7 Hz), 5.36 (d, 1H,
5a,b: yield 41%, bp 106–110 °C (3 torr), nD20 1.5346, d420 1.0578.
1H NMR (400 MHz, CDCl3) d: 5a (Z-isomer): 1.60 (s, 6H, Me), 5.96 (d,
3
3
3
3
trans-CH=C, Jtrans 17.4 Hz), 5.93 (dd, 1H, C–CH=C, Jcis 10.7 Hz,
3Jtrans 17.4 Hz). 13C NMR (100 MHz, CDCl3) d: 22.48 (C-3, C-5), 24.75
(C-4), 34.05 (C-2, C-6), 91.19 (NC), 117.96 (=CH2), 138.38 (=CH). IR
(neat, n/cm–1): 1530 (NO2), 1635 (C=C), 3090 (=CH2). Found (%): C,
61.83; H, 8.56; N, 9.14. Calc. for C8H13NO2 (%): C, 61.91; H, 8.44; N,
9.03.
1H, NCCH=C, J 12.5 Hz), 6.78 (d, 1H, CH=C, J 12.5 Hz), 7.12–7.45
(m, 5H, Ph); 5b (E-isomer): 1.43 (s, 6H, Me), 6.37 (d, 1H, NCCH=C,
3J 16.1 Hz), 6.60 (d, 1H, NCC=CH, 3J 16.1 Hz), 7.12–7.45 (m, 5H, Ph).
IR (neat, n/cm–1): 1535 (NO2), 1595, 1605, 1655 (C=C), 3020, 3055,
3080 (=CH). Found (%): C, 69.21; H, 6.77; N, 7.08. Calc. for
C11H13NO2 (%): C, 69.09; H, 6.85; N, 7.32.
– 63 –
Kukharev, Boris F.
