68
F. Al-Omran and A. A. El-khair
Vol 51
Figure 8. Perspective view and atom labeling of X-ray structure 13. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Table 9
product, so formed, was collected by filtration and crystallized
from a mixture of DMF: EtOH (2:1,v/v) as golden brown
crystals, 1.67 g (75%).
Bond length (Å) for compound 13.
Atom
Atom
Distance
Atom Atom
Distance
Method B. A mixture 7 (1.67 g, 10mmoles), a-chloroacetone
(7.9g, 10mmoles), and anhydrous potassium carbonate (1.38 g,
10mmoles) in Me2CO (100mL) was refluxed in water bath for
3 h. The solvent was then evaporated under reduced pressure. The
solid product, so formed, was collected by filtration and
crystallized from EtOH as white crystals of 1-(benzothiazol-2-
ylthio)propanone (1), 1.47g, (66%), mp 67–68ꢁC, (lit [21] mp
S1
S2
C1
C7
C10
C7
C9
C12
C6
C4
C6
C13
C12
1.718 (11)
1.743 (12)
1.213 (15)
1.285 (14)
1.282 (13)
1.123 (16)
1.410(13)
1.347 (18)
1.367 (17)
1.460 (14)
1.444 (16)
S1
C7
C8
C6
N3
C10
C2
C3
C5
C9
C11
1.774 (10)
1.788 (10)
1.409 (15)
1.406 (13)
1.354 (13)
1.415 (18)
1.38 (3)
1.366(19)
1.519 (17)
1.502 (14)
S2
O1
N1
N2
N4
C1
C3
C5
C9
C11
N1
N2
N3
C1
C2
C4
C8
C10
67ꢁC; IR:
1721cmꢀ1 (keto CO); 1H-NMR (DMSO-d6):
nmax
d
H 2.30 (1H, 3H, CH3), 4.48 (s, 2H, CH2), 7.36 (t, 1H, J = 8.0 Hz,
H-5), 7.44 (t, 1H, J = 8.0 Hz, H-6), 7.83 (d, 1H, J = 8.0 Hz, H-7),
8.01 (d, 1H, J = 8.0 Hz, H-4) ppm; 13C NMR (DMSO-d6): dC
201.6 (CO),165.9 (C-2), 152.5 (C-3a), 134.8 (C-7a), 126.4 (C-6),
124.5 (C-5), 121.8 (C-4), 121.1 (C-7), 43.3 (CH2), 28.9 (CH3)
ppm; ms: m/z 223 [M+]. Anal. Calcd. for C10H9NS2O (223.31):
C, 53.87; H, 4.06; N, 6.27. Found: C, 53.97; H, 3.97; N, 6.38.
2-Amino-5-(benzothiazol-20-yl thio)-4-methylthiophene-
Table 10
Bond lengths (Å) for compound 13.
3-carbonitrile (12).
A mixture of 1 (2.23 g, 10mmoles),
Atom
Atom
Distance
Atom
Atom
Distance
malononitrile (0.66 g,10mmoles) and elemental sulfur (0.32 g,
10mmoles) in DMF: EtOH (2:1, v/v) containing Et3N, (1mL)
was refluxed for 3 h. The reaction mixture was left to cool at room
temperature. The solid product, so formed, was collected by
filtration and crystallized from EtOH as brown crystals, 2.5g
(83%); mp 158-160ꢁC. IR: nmax 3359–3424 (NH2), 2200 (CN)
cmꢀ1; 1H-NMR (DMSO-d6): dH 2.31 (s, 3H, CH3), 7.22–7.93 (m,
4H, aromatic protons), 13.75 (bs., 2H, NH2, D2O exchangeable)
ppm; 13C NMR (DMSO-d6): d 31.2 (CH3), 109.3, 112.9, 116.1,
122.1, 124.6, 127.5, 129.8, 141.1, 141.7, 142.3, 147.6, 158.1
(aromatic carbons and CN), ppm; ms m/z 303 [M+]. Anal. Calcd.
for C13H9N3S3 (303.42): C, 51.46; H, 2.99; N, 13.84. Found: C,
51.50; H, 2.91; N, 13.82.
N3
C3
C5
C8
C11
C13
H3
H3A
H5
H8B
H11B
H13B
0.86
0.93
0.93
0.97
0.97
0.96
C2
C4
C8
C11
C13
C13
H2
H4
H8A
H11A
H13A
H13C
0.93
0.93
0.97
0.97
0.96
0.96
[21] mp 180ꢁC; IR: nmax 3437 cmꢀ1 (NH); 1H-NMR (DMSO-d6):
dH, 7.28 (d, 1H, J = 8.0 Hz, H-5), 7.31 (d, 1H, J = 8.0 Hz, H-6),
7.41(d, 1H, J = 8.0Hz, H-7)), 7.69 (d, 1H, J = 8.0Hz, H-4), 13.8
(bs., 1H, SH, D2O exchangeable) ppm; 13C NMR(DMSO-d6): dC
189.8 (C-2), 141.2 (C-3a), 129.3 (C-7a), 127.1 (C-6), 124.2 (C-5),
121.7 (C-4), 112.4 (C-7) ppm; ms: m/z 167 [M+]. Anal. Calcd. for
C7H5NS2 (167.25): C, 50.27; H, 3.01; N, 8.37. Found: C, 50.33;
H, 3.02; N, 8.72.
2-(benzothiazol-2-yl-thio)propanone cyanoacetyl hydrazone
(13). A mixture of 1 (2.23 g, 10 mmoles) and cyanoacetohydrazide
(0.99 g, 10 mmoles) in 1,4-dioxane (20 mL) was refluxed for 3 h.
The reaction mixture was left to cool at room temperature for
24h. The solid product, so formed, was collected by filtration and
crystallized from mixture of EtOH: dioxane (2:1, v/v) as yellow
crystals, 2.67g (78.8%), mp 177–179.IR: nmax 3232 (NH), 2264
Reaction of 1 with phenyl isothiocyanate and KOH
Method A.
A mixture of 1 (2.23 g, 10 mmoles), phenyl
isothiocyanate (1.35 g 10 mmoles), and potassium hydroxide
(0.56 g, 10 mmoles) in DMF (20 mL) was stirred at room
temperature for 8 h. To a stirred solution, chloroacetone (7.9 g,
10 mmoles) was added and refluxed for 3 h. The reaction
mixture was allowed to cool at room temperature, then poured
into ice-cold water and neutralized with HCl (10%). The solid
(CN), 1696 (C═O) cmꢀ1 1H-NMR (DMSO-d6): dH 2.04
;
(s, 3H,CH3),4.04 (s,2H,COCH2) 4.25 (s,2H,SCH2), 7.38
(t, 1H, J = 8.0 Hz, H-5), 7.48 (t, 1H, J = 8. Hz, H-6), 7.87
(d, 1H, J = 8.0 Hz, H-7), 8.00 (d, 1H, J = 8.0 Hz, H-4), 10.98
(bs., 1H, NH, D2O exchangeable) ppm; 13C NMR (DMSO-d6):
dC 165.3 and 165.9 (C-2 and C═O),159.1 (C═N), 152.2 (C-3a),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet