Ethyl 4,6-dimethyl-3-(pyrrol-1-yl) selenolo[2,3-b]pyridine-2-carboxylate
(2) was synthesized by the reaction of previously prepared ethyl
3-amino-4,6-dimethyl selenolo[2,3-b]pyridine-2-carboxylate (1) with
2,5-dimethoxytetrahydrofuran in acetic acid. The pyrrolyl ester (2) was
converted into the corresponding carbohydrazide 3 which reacted
with acetyl acetone, aromatic aldehydes, carbon disulfide in pyridine,
and sodium nitrite to afford the corresponding dimethyl pyrazolyl 4,
arylidene carbohydrazides 5a–d, oxadiazolyl thiole 6, and caboazide
compound 8, respectively. The carboazide 8 reacted with different
alcohols and amines to give the corresponding carbamates 9a–c and
the aryl urea derivatives 10a–d. Heating of carboazide 8 in dry xylene
afforded the pyridoselenolo-pyrrolopyrazinone 11. The latter
compound was used as a versatile starting precursor for synthesis of
other pyridoselenolo-pyrrolopyrazine compounds. The newly synthesized
compounds and their derivatives were characterized by
elemental analysis and spectroscopy (IR, 1H-NMR, and mass spectra).
Some of the newly synthesized pyrrolyl selenolopyridine compounds
showed remarkable antioxidant activity compared to ascorbic acid