Synthesis of new 5-mercapto-1,3-oxazole derivatives on the basis of 2-acylamino-3,3-dichloroacrylonitriles and their analogs

Article abstract of DOI:10.1023/A:1023333011230

Enamides of the general formula Cl₂C=C(X)NHCOR¹, where X = CN, COOAlk, CONH₂, P(O)(OEt)₂, P(O)Ph ₂, PPh₃ Cl^-, were treated in succession with alkane- or arenethiols and silver ca

Full text of DOI:10.1023/A:1023333011230

Russian Journal of General Chemistry, Vol. 72, No. 11, 2002, pp. 1714 1723. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 11, 2002,
pp. 1818 1827.
Original Russian Text Copyright
2002 by Pil’o, Brovarets, Vinogradova, Golovchenko, Drach.
Dedicated to the centenary of Academician A.V. Kirsanov’s birthday
Synthesis of New 5-Mercapto-1,3-oxazole Derivatives
on the Basis of 2-Acylamino-3,3-dichloroacrylonitriles
and Their Analogs
S. G. Pil’o, V. S. Brovarets, T. K. Vinogradova, A. V. Golovchenko, and B. S. Drach
Institute of Bioorganic and Petroleum Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received August 27, 2001
Abstract Enamides+of the general formula Cl2C C(X)NHCOR1, where X = CN, COOAlk, CONH2,
P(O)(OEt)2, P(O)Ph2, PPh3 Cl , were treated in succession with alkane- or arenethiols and silver carbonate
to obtain 5-alkyl(aryl)thio-2-R1-4-X-1,3-oxazoles with high selectivity. The latter were converted into the
corresponding sulfonyl derivatives. Unlike 2-acylamino-3,3-dichloroacrylonitriles which react with sodium
hydrogen sulfide in a nonselective fashion, reactions of derivatives like Cl(ArS)C C(CN)NHCOR1 with
NaHS lead to hitherto unknown 5-arylthio-4-thiocarbamoyl-2-R1-1,3-oxazoles whose structure was confirmed
both by spectral methods and by cyclocondensation with bromoacetophenone according to Hantzsch. Heating
of some 2-aryl-5-mercapto-4-X-1,3-oxazoles with benzenethiols results in recyclization into the corresponding
2,4-disubstituted 5-arylthio-1,3-thiazoles, presumably due to prototropic tautomerism in the 5-mercapto-
oxazole fragment.
Reactions of accessible 2-acylamino-3,3-dichloro-
acrylonitriles I and structurally related enamides II
and III with sulfur-centered nucleophiles were
recently reviewed in [1] (which covers publications
over the last three decades). As shown in [2 4],
condensations of enamides I III with aliphatic and
aromatic thiols in the presence of triethylamine occur
quite regioselectively. While performing the present
work, we succeeded in considerably extending the
ring, such as CN, C(O)OMe, C(O)OEt, C(O)NH2,
+
P(O)(OEt)2, P(O)Ph2, PPh3 ClO4, etc. Elimination of
both aliphatic and aromatic thiols during the cycliza-
tion occurs almost equally readily. On the other hand,
the rate of cyclocondensation is strongly affected by
electron-acceptor power of the acyl residue in sulfur-
containing enamides: aromatic acid derivatives
undergo cyclization much more readily than do their
aliphatic analogs. It was especially important to
involve enamides IV VI in the synthesis of 5-aryl-
thio-4-X-1,3-oxazoles, for most of these were inacces-
sible previously. Apart from cyclocondensation of
appropriate enamides IV VI by the action of silver
carbonate, alkylthio group can be introduced into
position 5 of the oxazole ring via successive treatment
of enamides I III with sodium hydrogen sulfide and
alkylating agents [4, 5]. The latter route is more con-
venient, e.g., for preparation of substituted 5-alkyl-
thio-1,3-oxazoles having a triphenylphosphonium
group in position 4 [4]; however, this procedure is
almost unsuitable for the synthesis of 5-arylthio-1,3-
oxazole derivatives.
scope of the known transformations I
III VI, and I VII (Scheme 1), as well as
effecting the condensations I VIII and I IX
IV, II
V,
for the first time. As a result, we obtained six series of
sulfur-containing enamides which were brought into
further transformations with the goal of synthesizing
5-mercaptooxazole derivatives X XXI. The most
important were cyclocondensations of sulfur-contain-
ing enamides IV VI with silver carbonate. Though
the latter was proposed as a reagent for such cycliza-
tions as early as 1976 [2], the limited and sometimes
improper choice of sulfur-containing enamidonitriles
made it impossible to estimate the preparative value
of this approach in full measure.
Thus, the above two methods complement each
other, so that they make it possible to synthesize
numerous new 4-functionalized 5-alkylthio- and
5-arylthio-1,3-oxazoles X XII which could be con-
verted into sulfonyl derivatives XVI XVIII. The
latter are highly reactive toward nucleophiles. Treat-
We have found that cyclocondensations IV
X,
V
XI, and VI XII are particular cases of the
general method for preparation of numerous 5-mer-
capto-1,3-oxazole derivatives containing various elec-
tron-acceptor substituents in position 4 of the oxazole
1070-3632/02/7211-1714$27.00 2002 MAIK Nauka/Interperiodica

SYNTHESIS OF NEW 5-MERCAPTO-1,3-OXAZOLE DERIVATIVES
1715
Scheme 1.
H
3R2SH, 3Et3N (R1 = ClCH2, X = CN)
2R2SH, 2Et3N
X
N
R1
1) NaSH (excess); 2) R2Hlg;
3) NaClO4
Cl
Cl
1) NaSH (excess); 2) I2
X = CN
O
Ia If, IIa IId, IIIa IIId
R2SO2Na
R2SH, Et3N
X = CN
H
N
H
N
H
N
H
X
CN
SR2
CN
SR2
CN
N
R1
R1
R1
SO2R2
SR2
R2S
R2S
2S
O
Cl
O
Cl
O R
IXa IXc
O
IVa IVl, Va Vd,
VIa VId
VIIa VIId
VIIIa VIIIc
NaSH
(excess)
Ag2CO3
(excess)
Ag2CO3
(excess)
NaSH
S
X
N
CN
N
CN
SR2
NH2
SR2
N
N
R1
R1
SR2
R1
SO2R2
O
R2S
O
O
O
Xa Xl, XIa XId, XIIa XIIe
XIIIa XIIId
XIVa, XIVb
XVa XVc
H2O2
(excess)
R2SH,
Et3N
BrCH2COPh
NaSH
Ph
S
CN
N
SH
O
X
CN
N
R2SO2Na
N
N
N
R1
R1
R1
S
SO2R2
O
R1
SR2
O
2
O
XVIa XVIf, XVIIa, XVIIb,
XVIIIa XVIIId
XXa, XXb
XXIa, XXIb
XIXa, XIXb
1) NaSH (excess); 2) HCl
1) PCl5; 2) S=C(NH2)2 (excess); 3) R3SH, Et3N; 4) NaClO4
X = COOAlk, +PPh Cl
+
3
X = PPh3Cl
X
X
H
X
X
N
N
N
R3SH,
1) ; 2) NaClO4
N
R1
SR3
R1
XXIIa XXIIc, XXIII
R1
R1
SR3
SH
S
H2O
O
O
S
S
O
XXIVa XXIVc, XXV
XXVIa XXVIe,
XXVIIa, XXVIIb
XXVIIIa XXVIIIe,
XXIXa, XXIXb
I, X = NC (a f); R1 = C6H5 (a), 4-CH3C6H4 (b), CH3 (c), ClCH2 (d), (CH3)3C (e), H (f). II, X = CH3OCO (a, b); R1 =
C6H5 (a), 4-CH3C6H4 (b); X = C2H5OCO, R1 = C6H5 (c); X = H2NCO, R1 = C6H5 (d). III, X = (C2H5O)2PO, R1 = C6H5
(a); X = (C6H5)2PO, R1 = C6H5 (b); X = (C6H5)3P+Cl (c, d); R1 = C6H5 (c), 4-CH3C6H4 (d). IV, X = NC (a l); R1 =
C6H5, R2 = C6H5 (a); R1 = 4-CH3C6H4, R2 = C2H5 (b); R1 = C6H5, R2 = 4-CH3C6H4 (c); R1 = R2 = 4-CH3C6H4 (d);
R1 = CH3, R2 = 4-CH3C6H4 (e); R1 = (CH3)3C, R2 = 4-CH3C6H4 (f); R1 = H, R2 = 4-CH3C6H4 (g); R1 = C6H5, R2 =
4-ClC6H4 (h); R1 = 4-CH3C6H4, R2 = 4-ClC6H4 (i); R1 = CH3, R2 = 4-ClC6H4 (j); R1 = (CH3)3C, R2 = 4-ClC6H4 (k);
R1 = H, R2 = 4-ClC6H4 (l). V, X = CH3OCO (a, b); R1 = C6H5, R2 = 4-ClC6H4 (a); R1 = 4-CH3C6H4, R2 = 4-ClC6H4 (b);
X = C2H5OCO, R1 = C6H5, R2 = 4-ClC6H4 (c); X = H2NCO, R1 = C6H5, R2 = 4-ClC6H4 (d). VI, X = (C2H5O)2P(O),
R1 = C6H5, R2 = 4-ClC6H4 (a); X = (C6H5)2P(O), R1 = C6H5, R2 = 4-CH3C6H4 (b); X = (C6H5)3P+Cl (c, d); R1 = C6H5,
R2 = 4-ClC6H4 (c); R1 = C6H5, R2 = 4-CH3C6H4 (d). VII, X = NC (a d); R1 = R2 = C6H5 (a); R1 = 4-CH3C6H4, R2 =
C6H5 (b); R1 = C6H5, R2 = 4-CH3C6H4 (c); R1 = 4-CH3C6H4, R2 = 4-ClC6H4 (d). VIII, X = NC, R2 = C6H5 (a c); R1 =
C6H5 (a), 4-CH3C6H4 (b), CH3 (c). IX, R2 = C6H5 (a), 4-CH3C6H4 (b), 4-ClC6H4 (c). X, X = NC (a l); R1 = C6H5 (a),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 11 2002

1716
PIL’O et al.
4-CH3C6H4 (b); R2 = C2H5 (a, b); R1 = C6H5 (c), 4-CH3C6H4 (d), CH3 (e), (CH3)3C (f), H (g); R2 = 4-CH3C6H4 (c g);
R1 = C6H5 (h), 4-CH3C6H4 (i), CH3 (j), (CH3)3C (k), H (l); R2 = 4-ClC6H4 (h l). XI, X = CH3OCO, R1 = C6H5 (a); X =
CH3OCO, R1 = 4-CH3C6H4 (b); X = C2H5OCO, R1 = C6H5 (c); X = H2NCO, R1 = C6H5 (d); R2 = 4-ClC6H4 (a d). XII,
R1 = C6H5 (a e); X = (C2H5O)2P(O), R2 = 4-ClC6H4 (a); X = (C6H5)2PO, R2 = 4-CH3C6H4 (b); X = (C6H5)3P+ClO4 (c
e); R2 = 4-ClC6H4 (c), 4-CH3C6H4 (d), CH3 (e). XIII, X = H2NC(S) (a d); R1 = R2 = C6H5 (a); R1 = 4-CH3C6H4, R2 =
C6H5 (b); R1 = C6H5, R2 = 4-CH3C6H4 (c); R1 = 4-CH3C6H4, R2 = 4-ClC6H4 (d). XIV, R1 = R2 = C6H5 (a); R1 =
4-CH3C6H4, R2 = C6H5 (b). XV, R2 = C6H5 (a), 4-CH3C6H4 (b), 4-ClC6H4 (c). XVI, X = NC (a f); R1 = 4-CH3C6H4,
R2 = C2H5 (a); R1 = C6H5, R2 = 4-CH3C6H4 (b); R1 = R2 = 4-CH3C6H4 (c); R1 = C6H5, R2 = 4-ClC6H4 (d); R1 = 4-CH3
C6H4, R2 = 4-ClC6H4 (e); R1 = CH3, R2 = 4-ClC6H4 (f). XVII, X = CH3OCO, R1 = 4-CH3C6H4, R2 = 4-ClC6H4 (a); X =
C2H5OCO, R1 = C6H5, R2 = 4-ClC6H4 (b). XVIII, R1 = C6H5 (a d); X = (C2H5O)2P(O), R2 = 4-ClC6H4 (a); X = (C6H5)2
P(O), R2 = 4-CH3C6H4 (b); X = (C6H5)3P+ClO4, R2 = CH3 (c); X = (C6H5)3P+ClO4, R2 = 4-CH3C6H4 (d). XIX, R1 =
C6H5, R2 = 4-CH3C6H4 (a); R1 = 4-CH3C6H4, R2 = C6H5 (b). XX, XXI, R1 = C6H5 (a), 4-CH3C6H4 (b). XXII, XXIV,
X = CH3OCO, R1 = C6H5 (a); X = CH3OCO, R1 = 4-CH3C6H4 (b); X = C2H5OCO, R1 = C6H5 (c). XXIII, XXV, X =
(C6H5)3P+Cl , R1 = C6H5. XXVI, XXVIII, X = CH3OCO (a d); R1 = C6H5, R3 = 4-ClC6H4 (a); R1 = 4-CH3C6H4, R3 =
4-ClC6H4 (b); R1 = C6H5, R3 = 4-methoxycarbonyl-2-phenyl-1,3-oxazol-5-yl (c); R1 = 4-CH3C6H4, R3 = 4-methoxycar-
bonyl-2-p-tolyl-1,3-oxazol-5-yl (d); X = C2H5OCO, R1 = C6H5, R3 = 4-ethoxycarbonyl-2-phenyl-1,3-oxazol-5-yl (e).
XXVII, X = (C6H5)3P+Cl , R1 = C6H5 (a, b); R3 = 4-CH3C6H4 (a), 4-ClC6H4 (b). XXIX, X = (C6H5)3P+ClO4, R1 =
C6H5 (a, b); R3 = 4-CH3C6H4 (a), 4-ClC6H4 (b).
ment of XVI XVIII with arenethiols in the presence
of triethylamine under mild conditions leads to re-
placement of the sulfonyl moiety in position 5 of
the oxazole ring by arylthio group due to effect of
strong electron-acceptor substituent at the neighboring
portant role in the complex transformation III XXI.
The possibility for oxidation of intermediate 4-cyano-
5-mercapto-1,3-oxazoles XX with benzenesulfinate
ion is beyond question; it was confirmed by model
experiment (see Experimental). From the preparative
C4 atom (see transformations XVI
X, XVII
X,
viewpoint, the transformation VIII
convenient than I XXI.
XXI is more
and XVIII
XII in Scheme 1). Obviously, at least
several of the transformations shown are important
from the preparative viewpoint. However, additional
studies are necessary to determine the scope and limits
of application of reagents XVI XVIII in the synthesis
of new 5-functionalized 1,3-oxazoles.
To conclude, it should be noted that 2,4-disubsti-
tuted 5-mercaptooxazoles XXII (X = COOAlk) and
+
XXIII (X = PPh3Cl ) react in a specific manner with
arene- and hetarenethiols on heating in ethanol or
acetic acid (see Scheme 1). Obviously, these reactions
involve intermediate formation of products XXIV
XXVII which are then converted into 5-mercapto-
thiazole derivatives XXVIII and XXIX. The structure
of the final recyclization products was proved by
independent synthesis of some of them via reaction
of 2-aryl-5-chloro-1,3-thiazol-4-yl(triphenyl)phospho-
nium salts with arenethiols [6]. The transformation
Unlike enamidonitriles I whose reactions with
sodium hydrogen sulfide take several pathways, their
accessible derivatives VII react with NaHS in a more
regioselective fashion, yielding previously unknown
5-arylthio-4-thiocarbamoyl-2-R1-1,3-oxazoles XIII.
The transformation of the cyano group into thiocarba-
moyl was confirmed by the IR spectra and was
reliably proved by the Hantzsch reaction of XIII with
XXII
XXVIII is especially important from the
bromoacetophenone (XIII
XIX). In is interesting
preparative viewpoint, for it leads to previously
inaccessible 5-mercapto-1,3-thiazole-4-carboxylic acid
derivatives. In these syntheses, the key stage is
recyclization which is likely to be favored by proto-
tropic tautomerism in the 5-mercaptooxazole frag-
ment, giving rise to nonaromatic structures XXIV
and XXV. The latter may be regarded as thio analogs
of saturated azlactones which are known to undergo
cleavage by the action of many reagents possessing
a labile hydrogen atom, thiols among them. The sub-
sequent elimination of water in acid medium and the
that structurally related enamidonitriles VII and
VIII differently react with sodium hydrogen sulfide
under the same conditions (DMF, 20 25 C). The
cyano group in VII is involved in the reaction,
whereas the cyano group in VIII remains intact; in
the latter case, the major products are bis(2-aryl-4-
cyano-1,3-oxazol-5-yl) disulfides XXI. Their structure
is consistent with the IR and mass spectral data. In
addition, compound XXIa was synthesized by an in-
dependent method by treatment of 2-benzoylamino-
3,3-dichloroacrylonitrile first with sodium hydrogen
sulfide and then with iodine [5]. It is quite probable
that intermediate products XIV and XX play an im-
cyclization XXVI
XXVIII or XXVII
XXIX
have some close analogies (cf. [7]). Probably, the
scope of the new recyclization could be extended even
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SYNTHESIS OF NEW 5-MERCAPTO-1,3-OXAZOLE DERIVATIVES
1717
in the nearest future, which could lead to development
of a general procedure for the synthesis of previously
inaccessible 1,3-thiazoles with functional substituents
in positions 4,5.
were obtained on a Varian VXR-300 instrument in
(CD3)2SO or CDCl3 using TMS as internal reference
(Table 1). The mass spectra were run on a Varian
MAT-311A spectrometer (Table 1). The yields, con-
stants, and elemental analyses of the newly syn-
thesized compounds are given in Table 2.
EXPERIMENTAL
The IR spectra were recorded on a Specord M-80
spectrometer in KBr (Table 1). The H NMR spectra
2-Acylamino-3,3-dichloroacrylonitriles Ia Id
were reported previously [9 11]. 3,3-Dichloro-2-pi-
1
Table 1. Spectral parameters of compounds IV, VII XIII, XVI XIX, XXI, and XXVIII
Comp.
no.
IR spectrum (KBr),
1H NMR spectrum [(CD3)2SO],a , ppm
1
, cm
IVa
1655 (C=O), 2225 (C N), 1.18 t (3H, CH3), 1.30 t (3H, CH3), 2.96 m (4H, 2CH2), 7.70 8.00 m (5H, C6H5),
3360 (NH as.) 10.17 s (1H, NH)
1640 (C=O), 2220 (C N), 1.17 t (3H, CH3), 1.29 t (3H, CH3), 2.38 s (3H, CH3C6H4), 2.95 m (4H, 2CH2),
3300 (NH as.) 7.35 d (2H arom.), 7.82 (2H arom.), 10.14 s (1H, NH)
1650 (C=O), 2215 (C N), 2.23 s (3H, CH3C6H4), 2.32 s (3H, CH3C6H4), 7.00 7.90 m (13H, 2C6H4, C6H5),
3220 3280 (NH as.) 10.35 s (1H, NH)
1635 (C=O), 2220 (C N), 2.23 s (3H, CH3C6H4S), 2.31 s (3H, CH3C6H4S), 2.37 s (3H, CH3C6H4CO), 6.50
IVb
IVc
IVd
3260 (NH as.)
7.25 m (12H, 3C6H4), 10.22 br.s (1H, NH)
IVe
IVf
1.91 s (3H, CH3), 2.30 s (6H, 2CH3C6H4), 7.00 7.20 m (8H, 2C6H4), 9.97 s (1H, NH)
1660 (C=O), 2220 (C N), 1.15 s [9H, (CH3)3C], 2.32 s (3H, CH3C6H4), 6.95 7.15 m (8H, 2C6H4), 9.29 br.s
3270 (NH as.)
(1H, NH)
IVg
IVj
2.32 s (6H, 2CH3), 7.00 7.25 m (8H, 2C6H4), 10.18 br.s (1H, NH)
1690 (C O), 2230 (C N), 1.98 s (3H, CH3), 7.10 7.50 m (8H, 2C6H4), 9.98 br.s (1H, NH)
3320 (NH as.)
IVk
IVl
1.17 s [9H, (CH3)C], 7.10 7.40 m (8H, 2C6H4), 9.51 s (1H, NH)
7.10 7.50 m (8H, 2C6H4), 10.34 s (1H, NH)
VIIab
1655 (C=O),c 2235 (C N),c 7.40 8.00 m (10H, 2C6H5), 10.57 s (0.6H, NH), 10.63 s (0.4H, NH)
3250 3280 (NH as.)
VIIbb
VIIcb
VIIIa
VIIIbb
VIIIcb
IXa
1650 (C=O),c 2230 (C N),c 2.39 s (3H, CH3), 7.20 7.90 m (9H, C6H4, C6H5), 10.46 s (0.7H, NH), 10.52
3230 3280 (NH as.)
(0.3H, NH)
1655 (C=O),c 2230 (C N),c 2.35 s (2.1H, CH3), 2.36 s (0.7H, CH3), 7.00 8.00 m (9H, C6H4, C6H5), 10.53 s
3260 (NH as.)
1715 (C=O), 2240 (C N),
3340 (NH as.)
(0.7H, NH), 10.61 s (0.3H, NH)
2.38 s (2.1H, CH3), 2.44 (0.9H, CH3), 7.30 8.10 m (9H, C6H4, C6H5), 10.78 s
(0.7H, NH), 10.82 s (0.3H, NH)
2.06 s (0.9H, CH3), 2.12 (2.1H, CH3), 7.60 8.10 m (5H, C6H5), 10.47 s (0.7H,
NH), 10.53 s (0.3H, NH)
1660 (C=O), 2225 (C N), 3.80 s (2H, CH2), 7.00 7.50 m (15H, 3C6H5), 10.23 s (1H, NH)
3220 (NH as.)
IXb
1655 (C=O), 2225 (C N), 2.25 s (3H, CH3C6H4SCH2), 2.32 s (6H, 2CH3C6H4), 3.63 s (2H, CH2), 6.90
3270 (NH as.)
7.40 m (12H, 3C6H4), 10.04 s (1H, NH)
IXc
1660 (C=O), 2230 (C N), 3.77 s (2H, CH2), 7.10 7.40 m (12H, 3C6H4), 10.29 s (1H, NH)
3260 (NH as.)
Xa
Xb
2260 (C N)
2260 (C N)
1.39 t (3H, CH3), 3.18 q (2H, CH2), 7.50 8.10 m (5H, C6H5)
1.38 t (3H, CH3), 2.42 s (3H, CH3), 3.14 q (2H, CH2), 7.37 d (2H arom.), 7.86 d
(2H arom.)
Xc
Xd
Xe
2260 (C N)
2260 (C N)
2250 (C N)
2.32 s (3H, CH3), 7.15 7.95 m (9H, C6H5, C6H4)
2.31 s (3H, CH3), 2.38 s (3H, CH3), 7.22 7.84 m (8H, 2C6H4)
2.36 s (3H, CH3), 2.46 s (3H, CH3C6H4), 7.20 d (2H arom.), 7.40 d (2H arom.)
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PIL’O et al.
Table 1. (Contd.)
Comp.
no.
IR spectrum (KBr),
1H NMR spectrum [(CD3)2SO],a , ppm
1
, cm
Xf
2255 (C N)
1.26 s (9H, 3CH3), 2.33 s (3H, CH3), 7.25 d (2H arom.), 7.34 d (2H arom.)
2.32 s (3H, CH3), 6.90 7.20 m (5H, C6H4, CH)
7.43 8.05 m (9H, C6H5, C6H4)
2.39 s (3H, CH3), 7.40 d (2H arom.), 7.52 d (2H arom), 7.60 d (2H arom.), 7.86 d
(2H arom.)
Xg
Xh
Xi
2220 (C N)
2255 (C N)
2260 (C N)
Xj
Xk
Xl
2250 (C N)
2250 (C N)
2225 (C N)
2.49 s (3H, CH3), 7.37 d (2H arom.), 7.43 d (2H arom.)
1.33 s (9H, 3CH3), 7.46 s (4H, C6H4)
7.15 7.32 m (5H, C6H4, CH)
XIa
XIb
XIc
XId
XIIa
XIIb
XIId
XIIIa
3.90 s (3H, OCH3), 7.42 7.80 m (9H, C6H5, C6H4)
2.35 s (3H, CH3), 3.85 s (3H, OCH3), 7.24 7.80 m (8H, 2C6H4)
1.31 t (3H, CH3), 4.32 q (2H, CH2), 7.45 7.85 m (9H, C6H5, C6H4)
7.43 7.88 m (11H, C6H5, C6H4, NH2)
1.27 t (6H, 2CH3), 4.14 q (4H, 2CH2), 7.42 7.94 m (9H, C6H5, C6H4)
2.28 s (3H, CH3), 7.17 7.92 m (19H, 3C6H5, C6H4)
2.34 s (3H, CH3), 7.21 7.98 m (24H, 4C6H5, C6H4)
7.30 7.95 m (10H, 2C6H5), 9.43 s (2H, NH2)
1700 (C=O)
1270 (P=O)
1190 (P=O)
1635 [ (NH2)],
3100 3600 (NH as.)
XIIIb
XIIIc
1635 [ (NH2)],
3300 3500 (NH as.)
1635 [ (NH2)],
2.38 s (3H, CH3), 7.30 7.90 m (9H, C6H5, C6H4), 9.41 s (2H, NH2)
2.38 s (3H, CH3), 7.31 7.92 m (9H, C6H5, C6H4), 9.41 s (2H, NH2)
3300 3500 (NH as.)
XIIId
XVIa
2.40 s (3H, CH3), 7.32 8.05 m (8H, 2C6H4), 9.36 s (2H, NH2)
1.34 t (3H, CH3CH2), 2.44 s (3H, CH3C6H4), 3.63 q (2H, CH2), 7.44 d (2H arom.),
7.96 d (2H arom.)
2260 (C N)
XVIb
XVIc
XVId
XVIed
XVIf
XVIIb
XVIIIa
XIXa
XIXb
XXIae
XXIbf
XXVIIIa 1700 (C=O)
XXVIIIb
XXVIIIc 1690 (C=O)
XXVIIId 1700 (C=O)
XXVIIIe 1680 (C=O)
2260 (C N)
2260 (C N)
2260 (C N)
2250 (C N)
2.44 s (3H, CH3), 7.55 8.10 m (9H, C6H4, C6H5)
2.40 s (3H, CH3), 2.44 s (3H, CH3), 7.35 8.05 m (8H, 2C6H4)
7.55 8.20 m (9H, C6H4, C6H5)
2.40 s (3H, CH3), 7.35 8.20 m (8H, 2C6H4)
2.56 s (3H, CH3), 7.63 d (2H arom.), 8.01 d (2H arom.)
1.37 t (3H, CH3), 4.40 q (2H, CH2), 7.55 8.20 m (9H, C6H5, C6H4)
1.37 t (6H, 2CH3), 4.25 q (4H, 2CH2), 7.50 8.20 m (9H, C6H5, C6H4)
2.27 s (3H, CH3), 7.10 8.10 m (15H, 2C6H5, C6H4, CH)
2.43 s (3H, CH3), 7.09 8.09 m (15H, 2C6H5, C6H4, CH)
7.60 8.03 m (10H, 2C6H5)
2.40 s (6H, 2CH3), 7.38 d (4H arom.), 7.87 d (4H arom.)
3.90 s (3H, OCH3), 7.40 7.80 m (9H, C6H5, C6H4)
2.33 s (3H, CH3), 3.90 s (3H, OCH3), 7.22 7.80 m (8H, 2C6H4)
3.99 s (3H, OCH3), 4.04 s (3H, OCH3), 7.84 8.10 m (10H, 2C6H5)
2.40 s (3H, CH3), 2.44 s (3H, CH3), 4.00 s (3H, OCH3), 4.00 s (3H, OCH3)
1.40 t (6H, 2CH3), 4.48 q (4H, 2CH2), 7.44 8.10 m (10H, 2C6H5)
2255 (C N)
2260 (C N)
a
1
b
c
The H NMR spectra of Xe, Xj, and XVIf were recorded in CDCl . Data for a mixture of Z and E isomers. Band with a
3
d
+
e
+
shoulder. Mass spectrum, m/z: 358 [M ], 199, 183, 155, 144, 119, 111, 103, 89, 77, 63. Mass spectrum, m/z: 402 [M ], 368,
341, 326, 310, 279, 265, 255, 236, 213, 202, 185, 169, 157, 149, 141, 121, 105, 95, 81, 69. Mass spectrum, m/z: 430 [M ], 216,
f
+
188, 183, 155, 135, 119, 103, 91, 77, 65.
valoylaminoacrylonitrile (Ie) and 3,3-dichloro-2-
formylacrylonitrile (If) were synthesized by the pro-
cedure described in [9] for compound Ic, by reactions
of the corresponding N-1,2,2,2-tetrachloroethylamides
with aqueous sodium cyanide. Alkyl 2-acylamino-3,3-
dichloroacrylates IIa IIc [12], 2-benzoylamino-3,3-
dichloroacrylamide (IId) [12], and phosphorus-con-
taining enamides IIIa IIId [13, 14] were synthesized
by known methods.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 11 2002

SYNTHESIS OF NEW 5-MERCAPTO-1,3-OXAZOLE DERIVATIVES
1719
Table 2. Yields, constants, and elemental analyses of compounds I, IV XIII, XVI XIX, XXI, XXVIII, and XXIX
Found, %
N
Calculated, %
S (P)
Comp. Yield,
mp,
(solvent)
C
Formula
no.
%
Cl
S (P)
Cl
N
Ie
70
65
75
78
76
80
70
75
60
85
80
75
85
70
75
70
70
75
75
94 96 (benzene)
147 149 (benzene)
96 98 (ethanol)
32.12 12.60
42.90 16.90
9.50
C8H10Cl2N2O
C4H2Cl2N2O
C14H16N2OS2
C15H18N2OS2
C24H20N2OS2
C25H22N2OS2
C19H18N2OS2
C22H24N2OS2
32.07 12.67
42.98 16.98
Ifa
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVi
IVj
IVk
IVl
Va
21.95
20.96
15.40
14.92
18.10
16.20
18.80
13.56
16.20
14.60
16.80
13.01
12.65
12.60
13.41
11.25
10.80
(5.20)
10.10
9.72
9.58 21.93
116 118 (ethanol)
162 164 (ethanol)
120 122 (ethanol)
144 146 (ethanol)
143 145 (ethanol)
118 120 (benzene)
135 137 (ethanol)
180 182 (ethanol)
123 125 (ethanol)
185 187 (toluene)
62 65 (ethanol)
9.08
6.68
6.47
7.85
7.02
8.18
9.14 20.93
6.73 15.39
6.51 14.89
7.90 18.09
7.06 16.17
8.23 18.84
5.94 13.60
7.09 16.22
6.40 14.66
7.35 16.82
2.86 13.08
2.78 12.71
2.78 12.71
5.86 13.49
2.46 11.28
2.37 10.84
(5.23)
C18H16N2OS2
15.05
17.90
16.10
18.42
14.40
13.90
13.81
14.79
12.40
5.90
7.05
6.35
7.30
2.82
2.75
2.74
5.80
2.42
2.33
C23H16Cl2N2OS2
C17H12Cl2N2OS2
C20H18Cl2N2OS2
C16H10Cl2N2OS2
C23H17Cl2NO3S2
C24H19Cl2NO3S2
C24H19Cl2NO3S2
C22H16Cl2N2O2S2
C25H24Cl2NO4PS2
C35H30NO2PS2
15.03
17.95
16.21
18.60
14.45
14.06
14.06
14.91
12.47
Vb
73 75 (ethanol)
Vcb
Vd
223 225 (ethanol)
178 180 (benzene)
234 236 (benzene)
VIa
VIb
VIIa
VIIb
VIIc
VIId
VIIIa
VIIIb
VIIIc
IXa
IXb
IXc
Xac
Xbd
Xce
Xd
Xe
Xf
Xg
Xh
Xi
Xj
Xk
Xl
82
84
85
84
70
70
75
85
85
85
62
65
76
75
52
50
50
76
75
56
58
50
65
65
60
50
50
148 150 (ethanol)
118 120 (ethanol)
134 136 (ethanol)
155 157 (ethanol)
165 167 (ethanol)
188 190 (ethanol)
115 117 (ethanol)
120 122 (ethanol)
128 130 (ethanol)
142 144 (ethanol)
58 60 (ethanol)
82 84 (ethanol)
78 80 (ethanol)
116 118 (ethanol)
52 54 (hexane)
11.20
10.80
10.76
19.45
10.11
9.52
8.82
8.50
8.48
7.70
8.05
7.70
9.80
6.40
5.80
5.15
12.10
11.40
9.50
9.10
12.08
10.24
12.88
8.90
8.50
C16H11ClN2OS
C17H13ClN2OS
C17H13ClN2OS
C17H12Cl2N2OS
C16H11ClN2O3S
C17H13ClN2O3S
C11H9ClN2O3S
C23H18N2OS3
C26H24N2OS3
C23H15Cl3N2OS3
C12H10N2OS
C13H12N2OS
C17H12N2OS
C18H14N2OS
C12H10N2OS
C15H16N2OS
C11H8N2OS
C16H9ClN2OS
C17H11ClN2OS
C11H7ClN2OS
C14H13ClN2OS
C10H5ClN2OS
C17H12ClNO3S
C18H14ClNO3S
C18H14ClNO3S
C16H11ClN2O2S
C19H19ClNO4PS
11.26
10.78
10.78
19.52
10.22
9.83
8.90 10.19
8.52 9.75
8.52 9.75
7.71 8.83
8.08 9.25
7.76 8.89
9.84 11.26
6.45 22.13
5.88 20.18
5.21 17.88
12.16 13.92
11.47 13.12
9.58 10.97
9.14 10.47
12.16 13.92
10.29 11.77
12.95 14.83
8.96 10.25
8.57 9.81
9.70
8.80
9.20
8.80
12.40
11.20
22.10
20.20
17.80
13.90
13.10
10.92
10.45
13.90
11.80
14.80
10.24
9.76
12.70
10.90
13.56
9.25
8.90
8.86
12.45
19.70
19.77
74 76 (hexane)
176 178 (ethanol)
83 85 (ethanol)
104 106 (ethanol)
68 70 (ethanol)
65 67 (ethanol)
180 182 (benzene)
110 112 (ethanol)
120 122 (ethanol)
98 100 (ethanol)
250 252 (ethanol)
36 38 (hexane)
11.22
10.80
11.34
10.85
14.10 11.12
12.05 9.50
14.90 11.80
14.14 11.17 12.79
12.11 9.57 10.95
14.98 11.84 13.55
XIa
XIb
XIc
XId
XIIa
10.10
9.80
9.72
10.60
8.25
4.01
3.85
3.84
8.40
3.30
10.25
9.85
9.85
10.72
8.37
4.04 9.27
3.89
3.89
8.47
3.31
8.91
8.91
9.69
9.65
7.50
7.57
(7.30)
(7.31)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 11 2002

1720
PIL’O et al.
Table 2. (Contd.)
Found, %
Calculated, %
Comp.
no.
Yield,
%
mp,
(solvent)
C
Formula
Cl
N
S (P)
Cl
N
S (P)
XIIb
60
62
153 155 (benzene)
142 143 (methanol)
3.00
6.80
(6.60)
C28H22NO2PS
3.00 6.86
(6.63)
2.23 5.11
(4.93)
XIId
5.85
2.35
5.40 C34H27ClNO5PS
(5.20)
5.64
XIIIa
XIIIb
XIIIc
XIIId
XVIa
XVIbf
XVIc
XVId
XVIe
XVIf
50
50
52
52
50
50
54
60
60
50
56
60
60
192 194 (ethanol)
206 208 (ethanol)
215 217 (ethanol)
194 196 (ethanol)
147 149 (ethanol)
180 182 (acetic acid)
200 202 (acetic acid)
176 178 (acetic acid) 10.20
208 210 (acetic acid)
130 132 (ethanol)
8.90
8.50
8.53
7.72
10.10
8.60
8.24
8.08
7.80
9.86
3.48
3.46
3.05
20.50 C16H12N2OS2
19.62 C17H14N2OS2
19.60 C17H14N2OS2
17.78 C17H13ClN2OS2
11.63 C13H12N2O3S
9.85 C17H12N2O3S
9.45 C18H14N2O3S
9.28 C16H9ClN2O3S
8.90 C17H11ClN2O3S
11.30 C11H7ClN2O3S
8.12 C18H14ClNO5S
8.20 C18H14ClNO5S
7.05 C19H19ClNO6PS
(6.70)
8.97 20.53
8.58 19.65
8.58 19.65
7.76 17.77
10.14 11.60
8.64 9.89
8.28 9.48
8.13 9.30
7.81 8.94
9.91 11.34
3.57 8.18
3.57 8.18
3.07 7.03
(6.79)
9.84
9.82
10.28
9.88
12.54
9.05
9.05
7.78
9.85
12.50
9.10
9.12
7.70
XVIIa
XVIIb
XVIIIa
208 210 (acetic acid)
138 140 (acetic acid)
107 109 (ethanol)
XVIIIb
XVIIIc
XVIIId
XIXa
60
70
65
50
54
>250 (ethanol)
2.76
2.40
2.00
6.50
6.48
6.40 C28H22NO4PS
(6.05)
5.45 C28H23ClNO7PS
(5.35)
4.71 C34H27ClNO7PS
(4.40)
15.10 C25H18N2OS2
2.80 6.42
(6.20)
2.40 5.49
(5.30)
2.12 4.86
(4.69)
6.57 15.03
>250 (acetic acid)
6.10
5.20
6.07
5.37
220 221 (methanol
water, 3:1)
190 192 (ethanol
water, 3:1)
195 197 (ethanol
water, 3:1)
XIXbg
15.05 C25H18N2OS2
6.57 15.03
XXIa
XXIb
XXVIIIa
XXVIIIb
XXVIIIc
XXVIIId
60
60
62
68
70
75
214 216 (dioxane)
196 198 (dioxane)
108 110 (ethanol)
150 152 (ethanol)
164 165 (acetone)
222 224 (nitro-
methane)
13.90
13.05
3.80
3.70
6.15
5.76
15.95 C20H10N4O2S2
14.95 C22H14N4O2S2
17.70 C17H12ClNO2S2
17.10 C18H14ClNO2S2
14.15 C22H16N2O5S2
13.30 C24H20N2O5S2
13.92 15.93
13.01 14.90
3.87 17.72
3.73 17.06
6.19 14.17
5.82 13.34
9.84
9.45
9.80
9.43
XXVIIIe
XXIXa
72
70
140 142 (methanol)
232 234 (methanol)
5.75
2.10
13.35 C24H20N2O5S2
9.95 C34H27ClNO4PS2
(4.85)
5.82 13.34
2.17 9.96
(4.81)
5.40
5.50
XXIXb
90
195 197 (methanol)
10.60
2.10
9.70 C33H24Cl2NO4PS2
(4.65)
10.67
2.11 9.65
(4.66)
a
b
Data for compound If prepared as described in [8], mp 148 150 C. Thick oily substance which cannot be distilled under reduced
c
pressure. It was brought into further syntheses without purification. Found, %: C 62.30; H 4.59. Calculated, %: C 62.59; H 4.38.
d
e
f
Found, %: C 63.68; H 5.37. Calculated, %: C 63.91; H 4.95. Found, %: C 69.53; H 4.43. Calculated, %: C 69.84; H 4.14. Found,
g
%: C 62.61; H 4.05. Calculated, %: C 62.95; H 3.73.
Found, %: C 70.17; H 4.62. Calculated, %: C 70.40; H 4.25.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 11 2002

SYNTHESIS OF NEW 5-MERCAPTO-1,3-OXAZOLE DERIVATIVES
1721
2-Acylamino-3,3-bis[alkylthio(arylthio)]acrylo-
nitriles IVa IVl. To a solution of 0.01 mol of en-
amidonitrile Ia Ic or If in 30 ml of anhydrous aceto-
nitrile we added 0.02 mol of the corresponding thiol
and 0.02 mol of triethylamine, the mixture was kept
for 8 h at 20 25 C, the precipitate was filtered off,
the filtrate was evaporated, and the residue was treated
with water, dried, and purified by recrystallization.
5-Alkyl(aryl)thio-2-aryl-4-cyano-1,3-oxazoles
Xa Xd, Xh, and Xi. a. A suspension of 0.01 mol of
compound IVa IVd, IVh, or IVi and 0.03 mol of
freshly prepared silver carbonate in 40 ml of anhy-
drous acetonitrile was refluxed for 8 10 h, the mixture
was left to stand for 8 h at 20 25 C, the precipitate
was filtered off, the filtrate was evaporated under
reduced pressure, the residue was treated with water,
and the precipitate was filtered off, dried, and purified
by recrystallization.
2-Benzoylamino-3,3-bis( p-chlorophenylthio)-
acrylonitrile (IVh) was reported in [3].
b. To a solution of 0.005 mol of compound
XVIe (see below) and 10 ml of dioxane we added
0.0075 mol of p-toluenethiol and 0.0075 mol of tri-
ethylamine. The mixture was refluxed for 8 h, kept
for 24 h at 20 25 C, and evaporated under reduced
pressure. The residue was washed with water, dried,
and purified by crystallization. Yield of Xd 70%.
Samples of Xd prepared as described in a and b
showed no depression of the melting point on mixing.
Alkyl 2-acylamino-3,3-bis(p-chlorophenylthio)-
acrylates Va Vc and 2-benzoylamino-3,3-bis(p-
chlorophenylthio)acrylamide (Vd) were synthesized
as described above for compounds IVa IVl; the reac-
tion mixture was kept for 48 h at 20 25 C.
Diethyl 1-benzoylamino-2,2-bis(p-chlorophenyl-
thio)ethenylphosphonate (VIa) and 1-benzoyl-
amino-2,2-bis(p-tolylthio)ethenyl(diphenyl)phos-
phine oxide (VIa) were synthesized as described
above for compounds IVa IVl.
2-Alkyl-5-arylthio-4-cyano-1,3-oxazoles Xe, Xf,
Xj, and Xk. A suspension of 0.01 mol of compound
IVe, IVf, IVj, and IVk and 0.03 mol of silver carbo-
nate in 40 ml of anhydrous dioxane was refluxed for
25 h. The mixture was then kept for 8 h at 20 25 C,
the precipitate was filtered off, the filtrate was
evaporated under reduced pressure, the residue was
treated with water, and the precipitate was filtered off,
dried, and purified by recrystallization.
1-Benzoylamino-2,2-bis[p-chlorophenylthio-
( p-tolylthio)]ethenyl(triphenyl)phosphonium
chlorides VIc and VId were synthesized as described
previously [4].
3-Arylthio-2-acylamino-3-chloroacrylonitriles
VIIa VIId. To a solution of 0.01 mol of compound
Ia or Ib in 30 ml of anhydrous acetonitrile we added
0.01 mol of the corresponding thiol and 0.01 mol of
triethylamine. The mixture was kept for 8 h at 20
25 C, the precipitate was filtered off, the filtrate was
evaporated under reduced pressure, and the residue
was treated with water, dried, and recrystallized from
ethanol. Compounds VIIa VIId were isolated as
mixtures of Z and E isomers (Tables 1, 2).
5-Arylthio-4-cyano-1,3-oxazoles Xg and Xl were
synthesized similarly.
Alkyl 2-aryl-5-p-chlorophenylthio-1,3-oxazole-4-
carboxylates XIa XIc were synthesized as described
above for compounds Xa Xd.
2-Aryl-5-arylthio-1,3-oxazol-4-yl(triphenyl)phos-
phonium perchlorates XIIc and XIId. a. To a solu-
tion of 0.01 mol of phosphonium salt VIc or VId in
acetonitrile we added 0.004 mol of freshly prepared
silver carbonate, and the resulting suspension was
refluxed for 18 20 h under stirring. The precipitate
was filtered off, the most part of the solvent was
removed under reduced pressure, 2 ml of a saturated
aqueous solution of sodium perchlorate was added to
the residue, and the precipitate was filtered off,
washed with water, and recrystallized from methanol.
2-Acylamino-3-chloro-3-phenylsulfonyacrylo-
nitriles VIIIa VIIIc. A suspension of 0.01 mol of
compound Ia Ic and 0.01 mol of anhydrous sodium
benzenesulfinate in 50 ml of anhydrous acetonitrile
was refluxed for 12 h. The mixture was then kept for
8 h at 20 25 C, the precipitate was filtered off, the
filtrate was evaporated under reduced pressure, and
the residue was treated with water, dried, and purified
by recrystallization.
2-Arylthioacetylamino-3,3-bis(arylthio)acrylo-
nitriles IXa IXc. To a solution of 0.01 mol of com-
pound Id [11] in 40 ml of anhydrous acetonitrile
we added 0.03 mol of the corresponding thiol and
0.03 mol of triethylamine, and the mixture was kept
for 8 h at 20 25 C. The precipitate was filtered off,
the filtrate was evaporated under reduced pressure,
and the residue was treated with water, dried, and
purified by recrystallization.
b. To a suspension of 0.001 mol of compound
XVIIIc (see below) in 20 ml of anhydrous acetonitrile
we added 0.001 mol of p-toluenethiol and 0.0012 mol
of triethylamine. The mixture was heated at 60 C
until it became homogeneous (3 h), the solvent was
removed under reduced pressure, 3 ml of methanol
and 2 ml of a saturated aqueous solution of sodium
perchlorate was added, the mixture was kept for 24 h,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 11 2002

1722
PIL’O et al.
and the precipitate was filtered off and purified by
melting point was observed on mixing samples of
XXIa prepared as described in a and b.
recrystallization from methanol. Yield of XIId 65%.
1
The H and IR spectra of two samples of XIId pre-
Methyl 2-aryl-4-p-chlorophenylthio-1,3-thiazole-
4-carboxylates XXVIIIa and XXVIIIb. To a solu-
pared as described in a and b were identical.
5-Methylthio-2-phenyl-1,3-oxazol-4-yl(triphenyl)- tion of 0.005 mol of compound XXIIa or XXIIb [5]
phosphonium perchlorate (XIIe) was obtained by
treatment of 5-methylthio-2-phenyl-1,3-oxazol-4-yl-
(triphenyl)phosphonium iodide [4] with an aqueous
solution of sodium perchlorate.
in 30 ml of ethanol we added 0.025 mol of p-chloro-
benzenethiol. The mixture was refluxed for 8 h and
was then kept for 8 h at 20 25 C, and the precipitate
was filtered off, washed with a saturated solution of
sodium hydrogen carbonate, and purified by recrys-
tallization.
2-Aryl-5-arylthio-4-thiocarbamoyl-1,3-oxazoles
XIIIa XIIId. To a solution of 0.005 mol of com-
pound VIIa VIId in 10 ml of dimethylformamide we
added 0.015 mol of freshly prepared sodium hydrogen
sulfide, the mixture was kept for 48 h at 20 25 C,
the precipitate was filtered off, the solvent was
removed from the filtrate under reduced pressure, the
oily residue was treated with 5% hydrochloric acid,
and the precipitate was filtered off and purified by
recrystallization.
4-Alkoxycarbonyl-2-aryl-1,3-oxazol-5-yl 4-alk-
oxycarbonyl-2-aryl-1,3-thiazol-5-yl sulfides
XXVIIIc XXVIIIe. A suspension of 0.005 mol of
compound XXIIa XXIIc [5] in 20 ml of methanol
or ethanol was refluxed for 30 40 min. The mixture
was cooled, and the precipitate was filtered off and
purified by recrystallization.
5-Arylthio-2-phenyl-1,3-thiazol-4-yl(triphenyl)-
phosphonium perchlorates XXIXa and XXIXb.
a. To a solution of 0.001 mol of 2-phenyl-4-triphenyl-
phosphonio-1,3-oxazole-5-thiolate [4] in 10 ml of
glacial acetic acid we added 0.01 mol of the corre-
sponding thiol. The mixture was heated to the boiling
point and saturated with hydrogen chloride over
a period of 2 h, 2 ml of a saturated aqueous solution
of sodium perchlorate was added, the mixture was
kept for 24 h at 20 25 C, and the precipitate was
filtered off and purified by recrystallization.
2-Alkyl(aryl)-5-arylsulfonyl-1,3-oxazoles XVIa
XVIf, XVIIa, XVIIb, and XVIIIa XVIIId. A solu-
tion of 0.005 mol of compound Xb Xd, Xh Xj, XIa,
XIb, XIIa, XIIb, XIId, or XIIe in 10 ml of glacial
acetic acid was heated to the boiling point, and three
1-ml portions of 30% hydrogen peroxide were added
through equal time intervals over a period of 2 h.
The mixture was kept for 8 h at 20 25 C, and the
precipitate was filtered off and purified by recrystal-
lization.
2-Aryl-5-arylthio-4-(4-phenyl-1,3-thiazol-2-yl)-
1,3-oxazoles XIXa and XIXb. To a solution of
0.005 mol of compound XIIIb or XIIIc in 15 ml of
ethanol we added 0.006 mol of bromoacetophenone,
and the mixture was refluxed for 2 h and kept for
8 h at 20 25 C. It was then evaporated by half in a
vacuum, the residue was treated with a saturated solu-
tion of sodium hydrogen carbonate until alkaline reac-
tion, the mixture was heated for 10 15 min to 50 60 C
and kept for 8 h at 20 25 C, and the precipitate was
filtered off and purified by recrystallization.
b. Compound XXIXb was also synthesized by
reaction of p-chlorobenzenethiol with 5-chloro-2-phe-
nyl-1,3-thiazol-4-yl(triphenyl)phosphonium chloride
[6]. No depression of the melting point was observed
on mixing samples of XXIXb prepared as described
in a and b.
Reaction of methyl 5-mercapto-2-phenyl-1,3-
oxazole-4-carboxylate with sodium benzenesulfi-
nate (general procedure). To a solution of 0.001 mol
of compound XXIIa in 10 15 ml of dimethylform-
amide we added an equimolar amount of anhydrous
sodium benzenesulfinate. The mixture was stirred for
3 days at 20 25 C, the solvent was removed under
reduced pressure, and the residue was treated with
water and recrystallized from ethanol. Yield of bis-
(4-methoxycarbonyl-2-phenyl-1,3-oxazol-5-yl) disul-
fide 75%, mp 154 155 C. The product was identical
Bis(2-aryl-4-cyano-1,3-oxazol-5-yl) disulfides
XXIa and XXIb. a. To a solution of 0.005 mol of
compound VIIIa or VIIIb in 10 ml of dimethylform-
amide we added 0.015 mol of sodium hydrogen
sulfide, the mixture was kept for 48 h at 20 25 C, the
precipitate was filtered off, the filtrate was evaporated
under reduced pressure, the residue was treated with
water, and the precipitate was filtered off, dried, and
purified by recrystallization.
1
(according to the H NMR and IR data) to that ob-
tained by oxidation of XXIIa with iodine [5].
REFERENCES
b. Compound XXIa was synthesized previously
by oxidation of crude 4-cyano-5-mercapto-2-phenyl-
1,3-oxazole with iodine [5]. No depression of the
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