EVALUATION OF SOME ANTIINFLAMMATORY PYRIMIDOBENZIMIDAZOLES SYNTHESIZED VIA NOVEL TIN(II) CHLORIDE HYDROCHLORIC-ACID ASSISTED WATER ADDITIONAND REDUCTION OF -(2-NITROARYL)-1,4-DIHYDROPYRIMIDINE-2(3H)-THIONES
Sm. Sondhi et al., EVALUATION OF SOME ANTIINFLAMMATORY PYRIMIDOBENZIMIDAZOLES SYNTHESIZED VIA NOVEL TIN(II) CHLORIDE HYDROCHLORIC-ACID ASSISTED WATER ADDITIONAND REDUCTION OF -(2-NITROARYL)-1,4-DIHYDROPYRIMIDINE-2(3H)-THIONES, Synthesis, (11), 1994, pp. 1175-1180
-(2-nitroaryl)-1,4-dihydropyrimidine-2(3H)-thiones (Ia-c) on reduction
with Al/Hg amalgam gave ,4,6-trimethyl-1,4-dihydropyrimidine-2(3H)-th
iones (IIa-c). The reduction of 4,4,6-trimethyl-1-(2-nitroaryl or 4-ni
trophenyl or phenyl)-1,4-dihydropyrimidine-2(3H)-thiones Ia-f) with Sn
Cl2/HCl gave 1-(2-aminoaryl or 4-aminophenyl or imethyl-1,4,5,6-tetrah
ydropyrimidine-2(3H)-thiones (IIIa-f). 1-(2-Aminoaryl)-6-hydroxy-4,4,6
-trimethyl- 1,4,5,6-tetrahydropyrimidine-2(3H)-thiones (IIIa-d) underg
o cyclization to give pyrimido[3,4-a]benzimidazoles IVa-d when refluxe
d for 2 h in ethanol using a catalytic amount of sulfuric acid. Pyrimi
do[3,4-a]benzimidazole IVa undergoes S-alkylation when treated with et
hylbromo-acetate to give S-alkylated pyrimido[3,4-a]benzimidazole VI.
nyl)-6-hydroxy-4,4,6-trimethyl-1,4,5,6-tetrahydro- pyrimidine-2(3H)-th
ione (IIIe) on stirring at r.t. with ethanol and a catalytic amount of
sulfuric acid gave 1-(4-aminophenyl)-6-ethoxy-4,4,6-trimethyl-1 ,4,5,
6-tetrahydropyrimidine-2(3H)-thione (V). Compounds IIIa,b,c, IVa-d and
VI were tested for anti-inflammatory activity, IIIa,b,c, IVa and VI w
ere inactive, whereas IVb and IVc showed 14% and 34% activity, respect
ively, at 100 mg/kg p.o. Compound IVc showed 28% activity at 25 mg/kg
p.o. which is almost equipotent to phenylbutazone (30 mg/kg p.o.).