B. Narayana et al. / European Journal of Medicinal Chemistry 39 (2004) 867–872
871
Ar–H), d 7.38 (t, 1H, Ar–H), d 7.53 J = 6.20 (d, 1H, Ar–H), d
7.55 (s, 1H, Ar–H) d 7.93 (s, 1H CONH2), d 8.21 (s, Ar–H,
Thiazole–H) Anal. calculated for C16H12BrN3O2S: N, 10.76;
found: N, 10.67.
tion of the reaction the reaction mixture was poured in 100 ml
DM water and the precipitated product was filtered. Crude
product was recrystallised from dimethylformamide–ethanol
mixture. In the similar way converted 5-(2-(N-substituted
aryl)-1,3-thiazol-5-yl)-2-hydroxy benzamides to corre-
sponding 2-alkoxy derivative.
6e 2-Hydroxy-5-{2-[(3-chlrophenyl) amino]-1,3-thiazol-
5-yl} benzamide; this compound was obtained as brownish-
yellow crystals in a yield of 52%, mp 272–274 °C (Dimethyl
formamide/ethanol); Anal. calculated for C16H12ClN3O2S:
N, 12.15; found: N, 12.13.
8a 5-(2-Methyl-1, 3-thiazol-5-yl)-2-propoxybenzamide;
this compound was obtained as yellow micro crystals in a
yield of 90%, mp 180–182 °C (Dimethylformamide/
ethanol); 1H-NMR: (DMSO-d6), d 1.10(t, 3H, –CH3), d 1.92
(sextet, 2H, –CH2–), d 2.76 (s, 3H, –CH3), d 7.87 (t, 2H,
–CH2), d 5.97 (s, 1H, CONH2), d 7.03 (J = 8.72) (d, 1H,
Ar–H), d 7.3 (s, 1H, thiazole-H), d 7.88 (s, 1H, CONH2), d
8.08 (dd, 1H,Ar–H), d 8.63 (J = 2.32) (d, 1H,Ar–H), MS: m/z
276 (M+, I = 25%), 217 (M–o–propyl, I = 100%); Anal.
calculated for C14H16N2O2S: N, 10.14; found: N, 10.05.
6f 2-Hydroxy-5-{2-[(4-chlrophenyl) amino]-1,3-thiazol-
5-yl} benzamide; this compound was obtained as light-
yellow crystals in a yield of 49%, mp 268–272 °C (Dimethyl-
formamide/ethanol); MS: m/z 345 (M+, I = 20%), 330
(M–NH2, I = 10%), 328 (M–OH, I = 25%); Anal. calculated
for C16H12ClN3O2S: N, 12.15; found: N, 12.04.
6g 2-Hydroxy-5-{2-[(2-(trifluoromethyl) phenyl) amino]-
1,3-thiazol-5-yl} benzamide: this compound was obtained as
brownish yellow crystals in a yield of 55%, mp 178–182 °C
(Dimethylformamide/ethanol); 1H-NMR: d 6.66 (s, 1H,
NH), d 7.16 J = 8.79 (d, 1H, Ar–H), d 7.6 (s, 1H, Ar–H), 7.57
(s, 1H, –CONH2), d 7.97 (s, 1H, CONH2), d 7.6 (dd, 2H,
Ar–H), d 7.63 (t, 1H, Ar–H), 7.76 (t, 1H, –Ar–H), d 7.86
J = 7.68 (d, 1H, Ar–H), d 7.71 J = 10.40 (d, 1H, Ar–H), d 8.25
(s, 1H, thiazole–H); MS: m/z 341(M–F2, I = 10%); Anal.
calculated for C17H12F3N3O2S: N, 11.08; found: N, 11.01.
8b 5-(2-Amino-1, 3-thiazol-5-yl)-2-propoxybenzamide;
this compound was obtained as yellow micro crystals in a
yield of 92%, mp 210–212 °C (Dimethylformamide/
ethanol); Anal. calculated for C13H15N3O2S: N, 15.16;
found: N, 15.03.
8c 5-(2-Anilino-1, 3-thiazol-5-yl)-2-propoxybenzamide;
this compound was obtained as white crystals in a yield of
95%, mp 245–248 °C (Dimethylformamide/ethanol); Anal.
calculated for C19H19N3O2S: N, 11.89; found: N, 11.78.
6h 5-{2-[(3-Chloro-4-methylphenyl) amino]-1,3-thiazol-
5-yl}-2-hydroxybenzamide: this compound was obtained as
off-white plates in a yield of 62%, mp > 300 °C (Dimethyl-
formamide/ethanol); Anal. calculated for C17H14ClN3O2S:
N, 11.68; found: N, 11.52.
8d 5-{2-[(4-Methylphenyl) amino]-1,3-thiazol-5-yl}-2-
propoxybenzamide; this compound was obtained as light
pink micro crystals in a yield of 94%, mp 202–205 °C
(Dimethylformamide/ethanol); Anal. calculated for
C20H21N3O2S: N, 11.44; found: N, 11.49.
6i 2-Hydroxy-5-[2-(pyridin-2-ylamino)-1,3-thiazol-5-yl]
benzamide: this compound was obtained as light-yellow
powder in a yield of 57%, mp > 300 °C (Dimethyl-
formamide/ethanol), MS: m/z 312 (M+, 75%), 295 (M–OH,
100%), 267 (M–CONH2); Anal. calculated for
C15H12N4O2S: N, 17.94; found: N, 17.46.
8e 2-Butoxy-5-(2-methyl-1,3-thiazol-5-yl)benzamide:
this compound was obtained as light-yellow microcrystals in
a yield of 94%, mp 148–150 °C (Dimethylformamide/
ethanol); 1H-NMR: (DMSO-d6), d 2.77 (s, thiazole –CH3), d
8.62 (thiazole–H), d 5.89 and 7.87 (two s, –NH2 of amide
group), d 7.02 J = 8.68 (d, 1H, Ar–H) and d 8.12 (dd, 2H,
Ar–H), d 7.35 (s, thiazole-H), [d 0.99–1.04 (t), d 4.16–
4.20(t), at d 1.47–1.59 (sextet) and d 1.83–1.93 (quintet)-
butyl side chain], MS: m/z 290(M+, I = 28%), 217 (M–O–
butyl, I = 100%); Anal. calculated for C15H18N2O2S: N, 9.65;
found: N, 9.64.
6j 2-Hydroxy-5-{2-[(6-methylpyridin-2-yl)amino]-1,3-
thiazol-5-yl}benzamide: this compound was obtained as
light-yellow powder in a yield of 68%, mp > 300 °C
(Dimethylformamide/ethanol); IR: (KBr, cmax
,
cm–1):
3433.1 (–NH–), 3031.9 (–CH3), 1622 and 1558.4 (CONH2),
1446 (C=C), 1336 (C=N), 1257.5 (C=S); Anal. calculated for
C16H14N4O2S: N, 17.17; found: N, 17.02.
8f 5-(2-Anilino-1,3-thiazol-5-yl)-2-butoxybenzamide:
this compound was obtained as white crystals in a yield of
92%, mp 248–250 °C (Dimethyl formamide/ethanol); IR
(KBr, cmax, cm–1): 3462 (OH), 3300 (NH), 2929 and 2871.8
(C–Hstr), 1666.4 (–CONH2), 1593.1 and 1562 (NHdef), 1271
(C–Ostr), 1163 (C=N) and 1082 (C=S), d 0.98 (t, 3H, –CH3),
1H-NMR: (DMSO-d6); d 1.42–1.55 (quintet, 2H, –CH2–), d
1.75–1.88 (sextet, 2H, –CH2–), d 4.05–4.01 (t, 2H, –CH2), d
5.94 (s, 1H, CONH2), d 6.73 (s, 1H, thiazole–H), d 6.76–6.79
(J = 8.7) (d, 1H, Ar–H), d 7.07 (dd, 1H, Ar–H), d 7.26–7.41
(m, 3H,Ar–H), d 7.75 (s, NH, CONH2), d 8.08 (s, 1H,Ar–H),
d 8.19 (s, 1H, 1H, Ar–H); Anal. calculated for C20H20N3O2S:
N, 11.47; found: N, 11.34.
4.5. General procedure for the preparation of 5-(2-substi-
tuted-1,3-thiazol-5-yl)-2-alkoxy benzamides 5-(2-(N-
substituted aryl)-1,3-thiazol-5yl)-2-alkoxy benzamides
(8a–g)
The 5-(2-substituted-1,3-thiazol-5-yl)-2-hydroxy benza-
mide (0.01 mol), n-alkyl bromide (7a–b), (0.012 mol) and
anhydrous potassium carbonate (0.015 mol) were taken in
dry DMF and heated to 60 °C and maintained for 6–7 h under
stirring. Reaction was monitored by TLC. After the comple-