Reactions of Tri(1-propenyl)amine with elemental sulfur

Article abstract of DOI:10.1023/A:1016563626207

The reaction of tri(1-propenyl)amine with elemental sulfur in bipolar aprotic solvent (DMF, DMSO) at 50°C within 1.5 h furnished 5-methyl-2-ethylthiazole in 62% yield. 2H,5H-5-methyl-2-ethylthiazole, 2-hydroxy-5-methylbenzaldehyde were found among the sid

Full text of DOI:10.1023/A:1016563626207

Russian Journal of Organic Chemistry, Vol. 38, No. 4, 2002, pp. 591 592. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 4, 2002,
pp. 617 619.
Original Russian Text Copyright
2002 by Musorin.
Reactions of Tri(1-propenyl)amine with Elemental Sulfur
G. K. Musorin
Irkutsk Institute of Chemistry, Russian Academy of Science, Irkutsk, 664033 Russia
Received May 11, 2001
Abstract The reaction of tri(1-propenyl)amine with elemental sulfur in bipolar aprotic solvent (DMF,
DMSO) at 50 C within 1.5 h furnished 5-methyl-2-ethylthiazole in 62% yield. 2H,5H-5-methyl-2-ethyl-
thiazole, 2-hydroxy-5-methylbenzaldehyde were found among the side products. The formation paths of the
compounds obtained are suggested.
Reactions of aliphatic enamines with sulfur in
DMF at room temperature result in thioamides [1 3],
and substituted thiophenes arise at heating [4].
It was found that a reaction of tri(1-propenyl)-
amine (I) with elemental sulfur in DMF at 50 C
within 1.5 h afforded 5-methyl-2-ethylthiazole (II)
2H,5H-5-methyl-2-ethylthiazole (III) in an overall
yield of 65%.
1
In the H NMR spectrum of the synthesized sub-
stituted thiazole appears a signal from fragment
=CHN (7.26 ppm, q) corresponding to compound II
and is not observed a signal from group =CH S of
compound V that should be present at 6.69 ppm.
The reaction at room temperature takes the same
direction, but is considerably decelerated: complete
conversion of compound I is attained in 10 h. Similar
results were obtained at replacing DMF by DMSO.
Triallylamine did not react with elemental sulfur
under the above conditions. Also, the elemental selen-
ium was not involved in the reaction with compound
I in DMF. Taking into account that reaction of sulfur
with enamines occurs when a hydrogen atom is
present in -position of the latter and that thioenols
arise at the initial stage [4], it is reasonable to assume
that N-2-mercapto-1-propenyl-di(propenyl)amine (IV)
forms in the reaction in question that compound II
(path a) furnishes through cyclization-elimination.
According to published data [2, 4] the reaction of
elemental sulfur with enamines in DMF occurs with
isomerization of the initial enamine. Compound I in
reaction with sulfur in DMF does not undergo iso-
merization: this process should inevitably result in
formation of 4-methyl-2-ethyl-1,3-thiazole (V)
(path b).
Since in the absence of a solvent the reaction
between compound I and elemental sulfur does not
occur it should be assumed that sulfur is activated by
bipolar aprotic solvent to form zwitter-ions VI and
ion-radicals VII. Just these species take part in the
observed chemical processes.
X = DMSO, DMF.
In reaction of compound I with elemental sulfur
carried out in the presence of hydroquinone the
content of compound II in the reaction mixture
decreased by 22%, and compound III was not
detected by GC-MS method. In keeping with this fact
1070-4280/01/3804-591$27.00 2002 MAIK Nauka/Interperiodica

592
MUSORIN
CH2CS), 7.26 q (1H, HC=).
13
the formation of compound III may be presented as
NMR spectrum of
compound II, , ppm: 11.98 (CH3C=), 14.18
(CH3CH2), 26.95 (CH3CH2), 132.55 (CH3C=),
139.70 (HC=C), 171.34 (C=N). Mass spectrum of
compound II, m/z: 127.
follows.
1H NMR spectrum of compound III, , ppm, JHz:
3
0.99, 1.05t (3H, CH3CH2, J 7.4), 1.44, 1.46 d.d (3H,
CH3CH, 3J7.29), 1.75, 1.99d.q (2H, CH3CH2, 3J7.4),
3
4
4.36q.t (1H, CHCH3, J 7.3, JHCSCH 1.5); 4.35 q.d.d
4
(1H, CHCH3, 3J 7.3, JHCSCH 0.9), 5.64 m (1H,
4
CHC2H5), 7.23, 7.20 d.d. (1H, CH=N, JCH= NCH
2.5).
1
According to H NMR data compound III is an
13
NMR spectrum of compound III, ,ppm:
equilibrium mixture of erythro- and threo-isomers.
10.68, 10.54 (CH3CH2), 21.42, 20.82 (CH3CH),
32.28, 31.56 (CH2), 54.45, 54.14 (CHCH3), 86.16,
85.46 (CHCH2CH3), 164.45, 164.37 (CH=N). Mass
spectrum of compound III, m/z: 129.
The GLC and GC-MS analysis of the reaction
mixture revealed the presence of compound VIII
with m/z 136 in 11 13% content. From H NMR
1
spectrum [5] the structure of compound VIII was
deduced as 2-hydroxy-5-methylbenzaldehyde. It was
shown experimentally that the yield of this compound
is not affected by carrying out the reaction in the
presence of hydroquinone.
(b) A reaction of a mixture of 1.6 g (0.01 mol) of
compound I, 0.8 g (0.02 mol) of sulfur, and 25 ml of
DMF was carried out for 10 h at room temperature.
After standard workup we obtained 1 g of mixture
containing according to GLC data 79% of compound
II and 13% of compound VIII. GC-MS analysis
demonstrated that the peak corresponding to com-
pound II included also 5% of compound III. The
yields of compounds obtained are as follows: II, 63%;
III, 3%; VIII, 8%; unidentified compounds, 8%.
EXPERIMENTAL
GLC analysis of reaction mixtures was performed
on Chrom-5 instrument, column 1000 4 mm, sta-
tionary phase 10% SE-30 on Chromaton N-AW-
DMCS. Compounds obtained were isolated for
identification by preparative chromatography on
device PAKhV-0.7, column 1000 6 mm, stationary
phase the same as for analysis. Mass spectra were
(c) To a mixture of 0.7 g (0.005 mol) of compound
I, 0.2 g (0.006 mol) of sulfur, and 25 ml of DMF
was 10 wt% of hydroquinone (calculated on the
weight of the reaction mixture). The reaction mixture
was heated to 50 C for 1.5 h and subjected to usual
workup. We isolated 0.49 g of mixture containing
according to GLC data 13% of compound I, 60% of
compound II, and 11% of compound VIII. GC-MS
analysis demonstrated the absence of compound III.
The yields of compounds obtained are as follows: II,
49%; VIII, 9%; unidentified compounds, 16%.
1
measured on GC-MS instrument LKB-2091. H and
13C NMR spectra were recorded on spectrometer
Bruker DPX-400 at 400.13 and 100.62 MHz
respectively. As solvent was used CDCl3, as internal
reference HMDS.
Reaction of tri(1-propenyl)amine with sulfur. (a)
A mixture of 1.6 g (0.01 mol) of compound I, 0.6 g
(0.02 mol) of sulfur, and 25 ml of DMF was heated
to 50 C for 1.5 h. Then the reaction mixture was
diluted with water, the reaction products were ex-
tracted into ether, the extracts were washed with
water, dried on CaCl2, and subjected to fractional
distillation. We obtained 1.1 g of a mixture contain-
ing according to GLC data 82% of compound II and
12% of compound VIII. GC-MS analysis de-
monstrated that the peak corresponding to compound
II included also 8% of compound III. The yields of
compounds obtained are as follows: II, 56%; III,
5%; VIII, 8%; unidentified compounds, 6.4%.
REFERENCES
1. Mayer, R., Gewald K., Angew. Chem., 1967, vol. 79,
no. 2, pp. 298 311.
2. Sigeru, Oae., Khimiya organicheskikh soedinenii sery
(Chemistry of Organic Compounds of Sulfur), Mos-
cow: Khimiya, 1975.
3. Mayer, R. and Wehl, T., Angew. Chem., 1964, vol. 76,
no. 20, p. 861.
4. Voronkov, M.G., Vyazankin, N.S., Deryagina, E.N.,
Nakhmanovich, A.S., and Usov, V.A., Reaktsii sery s
organicheskimi soedineniyami (Reactions of Sulfur
with Organic Compounds), Novosibirsk.: Nauka, 1976.
5. Smith, W.B., Deavenport, D.L., and Ihrig, A.M.,
J. Am. Chem. Soc., 1972, vol. 94, no. 6, pp. 1959
1965.
1H NMR spectrum of compound II, , ppm: 1.34 t
(3H, CH3CH2), 2.40 d (3H, CH3CS), 2.94 q (2H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 4 2002