New self-transformation of cyanothioacetamide in the presence of bases

Full text of DOI:10.1134/S1070428012100247

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 10, pp. 1386–1387. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.D. Dyachenko, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48, No. 10, pp. 1389–1390.
SHORT
COMMUNICATIONS
New Self-transformation of Cyanothioacetamide
in the Presence of Bases
V. D. Dyachenko
Taras Shevchenko Lugansk National University, ul. Oboronnaya 2, Lugansk, 91011 Ukraine
e-mail: chem@luguniv.edu.ua
Received April 13, 2012
DOI: 10.1134/S1070428012100247
Cyanothioacetamide [1] is used in organic synthesis
mostly as CH acid component [2]. On the other hand,
two examples of its self-transformation have been
reported, namely self-condensation in boiling ethanol
in the presence of sodium ethoxide with formation of
4,6-diamino-2-thioxo-2,5-dihydropyridine-3-carboni-
trile [3] and Thorpe dimerization [4] to (E)-3-amino-2-
cyanopent-2-enebis(thioamide) [5].
pholin-4-yl)-3-thioxopropanethioamide [7]. Presum-
ably, compound II is formed via initial Thorpe dimer-
ization of I to give adduct A and its subsequent
cyclization to hydrogenated pyridine structure B which
loses hydrogen sulfide with formation of intermediate
C. Tautomerization of the latter yields final product II.
Alkylation of II with chloroacetanilide (III) in alkaline
medium afforded the corresponding sulfide, 2-(4,6-di-
amino-3-cyanopyridin-3-ylsulfanyl)-N-phenylacet-
amide (IV). This reaction is typical of substituted
2-thioxo-1,2-dihydropyridines [8] and 4,6-diamino-2-
selenoxo-1,2-dihydropyridine-3-carbonitrile [9] (a se-
lenium-containing analog of II).
The present communication describes a new self-
transformation of cyanothioacetamide (I) in ethanol at
20°C in the presence of an equimolar amount of
piperidine, which leads to the formation of 4,6-di-
amino-2-thioxo-1,2-dihydropyridine-3-carbonitrile
(II). Compound II was synthesized previously by reac-
tion of malononitrile dimer sodium salt with hydrogen
sulfide in anhydrous ethanol [6]. When morpholine
was used instead of piperidine, other conditions being
equal, transamination occurred with formation of
3-(morpholin-4-yl)-3-thioxopropanenitrile, whereas
the reaction in the presence of 2 equiv of morpholine
involved not only transamination but also intermolec-
ular transfer of hydrogen sulfide to produce 3-(mor-
4,6-Diamino-2-thioxo-1,2-dihydropyridine-3-car-
bonitrile (ІІ). Piperidine, 1 ml (10 mmol), was added
under stirring at 20°C to a solution of 1 g (10 mmol) of
cyanothioacetamide (I) in 20 ml of ethanol, and the
mixture was stirred for 4 h and left to stand for 48 h.
The precipitate was filtered off and washed with etha-
nol and hexane. Yield 0.76 g (46%), yellow powder,
mp 310°C (decomp., from BuOH); sublimes at 250°C;
1
published data [6]: mp 310–312°C. The IR, H NMR,
HN
CN
NH
NH
S
NH
CN
S
CN
S
2
NC
S
–H2S
NH2
H2N
HS
NH2
H2N
N
H
H2N
N
H
S
I
A
B
C
NH2
NH2
CN
CN
S
ClCH2CONHPh (III)
H
N
H2N
N
H
S
H2N
N
Ph
O
II
IV
1386

NEW SELF-TRANSFORMATION OF CYANOTHIOACETAMIDE
1387
and mass spectra of II were consistent with those
given in [6].
stage. The progress of reactions and the purity of prod-
ucts were monitored by TLC on Silufol UV-254 plates
(eluent acetone–hexane, 3:5); spots were visualized
under UV light or by treatment with iodine vapor.
2-(4,6-Diamino-3-cyanopyridin-3-ylsulfanyl)-
N-phenylacetamide (IV). Compound II, 1.7 g
(10 mmol), was dissolved in 15 ml of DMF, 5.6 ml
(10 mmol) of 10% aqueous potassium hydroxide and
1.7 g (10 mmol) of chloroacetanilide (III) were added
in succession under stirring, and the mixture was
stirred for 2 h and left to stand for 24 h. The mixture
was diluted with an equal volume of water, and the
precipitate was filtered off and washed with water,
ethanol, and hexane. Yield 2.33 g (78%), brown
powder, mp 165–168°C (from BuOH). IR spectrum, ν,
cm–1: 3398, 3318, 3195 (NH2), 1677 (C=O), 1644
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 10 2012