J. CHEM. RESEARCH (S), 1999 431
1H, enamine proton), 8.677 (s, 1H, enamine proton). MS (EI): m/z
Experimental
276 (M , 100%) (Anal. Calc.: C, 52.15; H, 5.84; N, 30.43. Found: C,
Mps are uncorrected. IR spectra were recorded on a Perkin-Elmer
1710 FTIR spectrometer as KBr disks. NMR spectra were recorded
on a Bruker AC300 spectrometer at 200 MHz for solutions of CDCl3
and [2H6]dimethyl sulfoxide with tetramethylsilane (TMS) as an
internal standard unless otherwise recorded. Mass spectra were
obtained on Finnigan 4500 (low resolution) spectrometers using elec-
tron impact (EI). The salts, ammonium 1,1,3-tricyano-2-methyl-
prop-2-enide 1a and sodium 2-amino-1,1,3-tricyanoprop-2-enide
1b were prepared according to literature methods.12
Reaction of 1a,b with H2S.öGeneral Method. H2S was passed for
2 h through a solution of salts 1a,b (0.01 mol) in absolute ethanol.
Fine crystals separated and were recovered by ¢ltration and puri¢ed
by recrystallisation from the appropriate solvent.
51.92; H, 6.00; N, 30.56%).
Preparation of Compound 9.öEquimolar amounts of
thieno[2,3-b]pyridine 4b (0.3 g, 0.001 mol) and DMFDMA (0.26 ml,
0.002 mol) in dry dioxane were re£uxed for 2 h. The resultant solid
was recovered by ¢ltration and recrystallised from dioxane, mp
165^167 8C, yield 3 g (85%). dH(DMSO) 3.08 (s, 3H, CH3), 3.11
(s, 3H, CH3), 5.45 (s, 1H, ring proton), 7.46±7.55 (m, 3H, Ar), 7.74
(m, 2H, Ar), 8.36 (s, 1H, CH), 8.55 (s 1H, CH), 8.65 (br exch., 1H,
NH). MS (EI): m/z 349 (M , 60%) (Anal. Calc.: C, 61.87; H, 4.33; N,
20.06. Found: C, 61.69; H, 4.25; N, 21.88%).
Preparation of 4-Substituted 6-Amino-3-cyano-2-methylthio-
pyridine-2(1H)-thione 10a,b.öPyridine-2(1H)-thione 3a,b (0.01 mol)
was dissolved in ethanol (25 ml)^sodium hydroxide (10%, 10 ml)
and treated with methyl iodide [2 ml(excess)] dropwise with stirring
at room temperature. The reaction mixture was left stirring at room
temperature for 2 h and the resultant solid recrystallised from ethanol
as colourless crystals.
6-Amino-3-cyano-4-methylpyridine-2(1H)-thione 3a. Crystallisa-
tion from ethanol, mp 260 8C (decomp.), yield 85%. IR: 3431, 3215
1
(NH2), 2150 cm (CN), dH(DMSO) 2.19 (s, 3H, CH3), 5.95 (s, 1H,
ring proton), 7.25 (br exchangeable, 2H, NH2), 12.25 (br exch., 1H,
NH). MS (EI): m/z 165 (M , 100%) (Calc.: C, 50.9; H, 4.27; N, 25.45.
Found: C, 50.77; H, 4.15; N, 25.34%).
6-Amino-3-cyano-4-methyl-2-methylthiopyridine-2(1H)-thione 10a.
Mp 218^220 8C, yield 1.43 g (80%). IR: nmax 3340, 3310 (NH2),
4,6-Diamino-3-cyanopyridine-2(1H)-thione 3b. Crystallisation
from ethanol, mp 310^312 8C, yield 65%. IR: 3346, 3215 (NH2),
1
2165 cm (CN), dH(DMSO) 2.22 (s, 3H, CH3), 2.5 (s, 3H, CH3), 6.1
(s, 1H, ring proton), 6.97 (br exch., 2H, NH2). MS (EI): m/z 179
1
2155 cm (CN), dH(DMSO) 5.29 (s, 1H, ring proton), 6.54 (br
exch., 2H, NH2), 6.69 (br exch., 2H, NH2), 11.19 (s, exch., 1H, NH).
(M , 100%) (Anal. Calc.: C, 53.62; H, 5.07; N, 23.46. Found: C,
53.77; H, 5.17; N, 23.28%).
MS (EI): m/z 166 (M , 100%) (Calc.: C, 43.37; H, 3.64; N, 33.74.
Found: C, 43.16; H, 3.42; N, 33.52%).
4,6-Diamino-3-cyano-2-methylthiopyridine-2(1H)-thione 10b. Mp
153^155 8C, yield 1.4 g (77%). IR: nmax 3430, 3320, 3205 (NH2),
2150 (CN), 1618, 1573 (CN, CC cm 1, dH(DMSO) 2.45 (s, 3H,
SCH3), 3.46 (br exch., 2H, NH2), 5.46 (s, 1H, ring proton), 6.23 (br
Preparation of Thieno[2,3-b]pyridines 4a,b and 8).öGeneral
Method. An equimolar mixture of pyridine-2(1H)-thione 3a,b or
6a (0.01 mol), phenacyl bromide (1.99 g, 0.01 mol) and potassium
carbonate in absolute ethanol were re£uxed for 2 h. After cooling
the mixture was diluted with water and the solid obtained recovered
by ¢ltration and puri¢ed by recrystallisation from the appropriate
solvent.
3,6-Diamino-2-benzoyl-4-methylthieno[2,3-b]pyridine 4a. Crystal-
lisation from ethanol, mp 280^282 8C, yield 2.4 g (86%). IR: nmax
3460, 3325, 3160 (NH2), 1630 (CO) cm 1. dH(DMSO) 2.61 (s, 1H,
CH3), 6.27 (s, 1H, ring proton), 6.84 (br exch., 2H, NH2), 7.49±7.53
(m, 3H, Ar), 7.67±7.73 (m, 2H, Ar), 8.00 (br exch., 2H, NH2). MS
exch., 1H, NH2). MS (EI): m/z 180 (M , 100%) (Anal. Calc.: C,
46.65; H, 4.48; N, 31.11. Found: C, 46.44; H, 4.60; N, 30.96%).
Received, 17th August 1998; Accepted, 29th March 1999
Paper E/8/06439C
References
(EI): m/z 283 (M , 70%) (Anal. Calc.: C, 63.59; H, 4.63; N, 14.84.
Found: C, 63.28; H, 4.33; N, 14.57%).
1
V. P. Litvino, L. A. Rodinovskaya, Yu. A. Sharanin, A. M.
Shestopalov and A. Senning, Sulfur Rep., 1992, 13, 155.
A. M. Shestopalov, V. K. Promomenkov, Yu. A. Sharanin, L.
A. Rodinovskaya and S. Yu. Sharanin, Zh. Org. Khim., 1984,
20, 1517.
A. M. Shestopalov, V. K. Promomenkov, Yu. A. Sharanin and
A. M. Shestopalov, Enaminocarbonyl Compounds in Synthesis
of 3-cyano-2(1H)-pyridinethiones, in Itogi Nauki i Techniki,
Ser. Organicheskaya Khimiya, ed. Kabachnie, VINITI,
Moscow, 1989, vol. 17, pp. 72^156 and references therein.
G. E. Elgemeier, M. M. Sallam, M. S. Sherif and M. H.
Elnagdi, Heterocycles, 1985, 23, 3107.
3,5,6-Triamino-2-benzoylthieno[2,3-b]pyridine 4b. Crystallisation
from ethanol, mp 240^242 8C, yield 2.3 g (82%). IR: nmax 3390,
3150 (NH2), 1637 (CO) cm 1. dH(DMSO) 5.66 (s, 1H, ring proton),
6.5 (br exch., 2H, NH2), 6.45 (br exch., 1H, NH2), 7.45±7.51 (m, 3H,
Ar), 7.64±7.69 (m, 2H, Ar), 8.36 (br exch., 1H, NH2). MS (EI): m/z
2
3
284 (M , 30%) (Anal. Calc.: C, 59.14; H, 4.26; N, 19.72. Found: C,
58.86; H, 4.39; N, 19.50%).
3-Amino-6-(N,N-dimethylformimdyl)-4-methylthieno[2,3-b]pyridi-
ne 8. Crystallisation from ethanol, mp 167^169 8C, yield 2.7 g (80%).
IR: nmax 3346, 3175 (NH2), 1632 (CO) cm 1. dH(DMSO) 2.64 (s, 1H,
CH3), 3.05 (s, 3H, NCH3), 3.18 (s, 3H, NCH3), 6.3 (s, 1H, ring
proton), 6.5 (br exch., 2H, NH2), 7.48±7.55 (m, 3H, Ar), 7.67±7.73
4
5
F. M. A. Galil, M. M. Sallam, M. S. Sherif and M. H. Elnagdi,
Liebigs Ann. Chem., 1986, 1639.
(m, 2H, Ar), 8.4 (s, 1H, enamine proton). MS (EI): m/z 338 (M ,
30%) (Anal. Calc.: C, 63.88; H, 5.37; N, 16.57. Found: C, 63.67;
H, 5.42; N, 16.65%).
Preparation of Pyridine-2(1H)-thiones 6a,b.öPyridine-2(1H)-
thione 3a,b (0.01 mol) and DMFDMA in dry dioxane were re£uxed
for 2 h. The solvent was then evaporated and the resulting solid col-
lected by ¢ltration and recrystallised from ethanol.
3-Cyano-6-(N,N-dimethylformimdyl)-4-methylpyridine-2(1H)-thi-
one 6a. Mp 186^188 8C, yield 1.7 g (76%). IR: nmax 2150 cm
(CN), dH(DMSO) 2.26 (s, 3H, CH3), 3.04 (s, 3H, NCH3), 3.16 (s, 3H,
NCH3), 6.42 (s, 1H, ring proton) 8.32 (s, 1H, enamine proton), 12.69
6
7
8
U. Schmidt and H. Kubitzek, Chem. Ber., 1960, 93, 1559.
H. Vieweg, S. Leistner and G. Wagner, Pharmazie, 1986, 41.
F. A. Abu-Shanab, A. D. Redhouse, J. R. Thompson and B. J.
Wake¢eld, Synthesis, 1995, 557.
F. A. Abu-Shanab, F. A. Ali and B. J. Wake¢eld, Synthesis,
1995, 923.
9
10 D. Briel, S. Dumke, G. Wagner and B. Olk, J. Chem. Res.,
1991, (S) 178; (M) 1841.
11 F. A. Abu-Shanab, M. H. Elnagdi, F. A. Ali and B. J.
Wake¢eld, J. Chem. Soc., Perkin Trans. 1, 1994, 1449.
12 A. W. Erian, Chem. Rev., 1993, 93, 1991 and references
therein.
13 D. H. Williams and I. Fleming, Spectroscopic Methods in
Organic Chemistry, McGraw-Hill, London, 4th edn., 1987.
14 K. Gewald, Chimia, 1980, 34, 101 and references therein.
15 H. Sliwa, D. Blondeau and R. Rydzkowsk, J. Heterocycl.
Chem., 1983, 20, 1613.
1
(br exch., 1H, NH). MS (EI): m/z 220 (M , 100%) (Anal. Calc.: C,
54.53; H, 5.50; N, 25.45. Found: C, 54.66; H, 5.34; N, 25.26%).
3-Cyano-4,6-bis(N,N-dimethylformimdyl)pyridine-2(1H)-thione 6b.
1
Mp 160^162 8C, yield 2.2 g (80%). IR: nmax 2160 cm
(CN),
dH(DMSO) 3.005 (s, 3H, NCH3), 3.013 (s, 3H, NCH3), 3.102 (s,
3H, NCH3), 3.131 (s, 3H, NCH3) 6.273 (s, 1H, ring proton), 8.184 (s,