Abstract:
The derivatives of isocoumarins, coumarins and 1,2,4-triazoles are prominent biological
agents used as a cure against a number of human ailments. The present work deals with
their synthesis. 3-(Halobenzyl)isocoumarins (5a-i) were synthesized by condensation of
2-(halophenyl)acetyl chlorides (3a-i) with homophthalic acid (4) at elevated temperature.
3-(Halobenzyl)isocoumarins
(5a-i)
were
converted
into
3-(halobenzyl)-3,4-
dihydroisocoumarins (8a-i) via ketoacids (6a-i) and hydroxyacids (7a-i). 3-
(Halobenzyl)isocoumarins (5a-i) converted to their thio analogues (10a-i) by treating
with Lawesson’s reagent (11) while their nitrogen analogues (12a-i) were obtained by
passing ammonia into the solution of 3-(halobenzyl)isocoumarins (5a-i) in 2-ethoxy
ethanol. These synthesized compounds were evaluated for urease inhibition and anti-
inflammatory activity. 3-(Halobenzyl)isocoumarins (5a-i) and ketoacids (6a-i) exhibited
moderate urease inhibition activity. While others showed non significant activity. The
isoquinolinone (12c) showed anti-inflammatory activity higher than standard compound
i-e indomethacin while all other compounds showed non significant anti-inflammation.
Reaction of hitherto unknown 4-chloro-3-(2,2,2-trifluoroacetyl)-2H-chromen-2-one (16a)
with different commercially availble anilines (19a-l) gave respective 3-(trifluoroacetyl) -
4-(arylamino)-2H-chromen-2-one (20a-l) which were then successfully cyclized to 7-
(trifluoromethyl)-6H-chromeno[4,3-b]quinolin-6-ones (21a-l) using conc. H2SO4. The
synthesis of 4-aryl-3-(trifluoroacetyl)-2H-chromen-2-ones (18a-n) was accomplished by
Suzuki coupling reaction of 4-chloro-3-(2,2,2-trifluoroacetyl)-2H-chromen-2-one (16a)
and aryl boronic acids (17a-n).
Synthesis of 1,2,4-triazoles (31a-o) was carried out by dehydrative cyclization of
thiosemicarbazides (20a-o) which in turn were synthesized by addition of hydrazides
(29a-i) on isothiocyanate (27m-n). These triazoles showed moderate antibacterial
activity. Finally the synthesized 1,2,4-triazoles (31a-o) were evaluated for their toxicity
and these showed low toxicity.
