REACTIONS OF 4-ISOTHIOCYANATO-4-METHYL-2-PENTANONE WITH AMINES HAVINGFUNCTIONAL-GROUP AT BETA-POSITION AND ANTIINFLAMMATORY EVALUATION OF RESULTING HETEROCYCLIC-COMPOUNDS
Rk. Sahu et al., REACTIONS OF 4-ISOTHIOCYANATO-4-METHYL-2-PENTANONE WITH AMINES HAVINGFUNCTIONAL-GROUP AT BETA-POSITION AND ANTIINFLAMMATORY EVALUATION OF RESULTING HETEROCYCLIC-COMPOUNDS, Phosphorus, sulfur and silicon and the related elements, 88(1-4), 1994, pp. 45-51
The reaction of 4-isothiocyanato-4-methyl-2-pentanone with o-phenylene
diamine at room temperature yielded isomeric mixture of 1,4,5,6-tetrah
ydro-6-hydroxyprimidine-2(3H)-thione (I), which on refluxing in MeOH w
ith catalytic amount of sulphuric acid cyclizes to yield the known pyr
imidobenzimidazole (IIa). The same product was also obtained by direct
condensation of o-phenylenediamine with 4-isothiocyanato-4-methyl-2-p
entanone in the presence of catalytic amount of acid and heating under
reflux for 8 h. The reaction of 4-nitro-1,2-phenylenediamine with 4-i
sothiocyanato-4-methyl-2-pentanone gave IIb. The reaction of o-aminoph
enol with 4-isothiocyanato-4-methyl-2-pentanone at pH 4.3 gave 1-(2'-h
ydroxyphenyl) -4,4,6-trimethyl-1,4-dihydro-pyrimidine-2(3H) thione (II
I), however the same reaction under strongly acidic conditions (pH sim
ilar to 1) gave the known pyrimidobenzoxazole (IV). The reaction of 4-
isothiocyanato-4-methyl-2-pentanone with o-aminothiophenol and 2-amino
ethanol under different pH conditions gave the known heterocycles V a
nd VI, respectively. The structures of these compounds are supported b
y IR, H-1 NMR and HRMS. Antiinflammatory evaluation of I, IIa, IIb, II
I, IV, V and VI at 100 mg/kg showed that compounds I, IIa, III, and IV
are inactive whereas, compounds IIb, V and VI showed 13%, 11%, and 21
% activity, respectively.