A new series of 2-aryl(alkyl)oxazoloquinolines (IV) were prepared by the reaction of 7-amino-8-hydroxyquinoline with aromatic (or aliphatic) aldehydes in the presence of piperidine as a catalyst. Interaction of 2-methyloxazolo[4,5-h]quinoIine with aromatic aldehydes in the presence of piperidine as a catalyst gave 2-stilbyloxazolo [4,5-h]quinolines. The structural configuration of the prepared compounds was determined by elemental and spectral analysis.

The synthesis of 3-methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydropyrazolo[5,4-b]
pyrimidino[5,4-e]pyridine-5-one (6) was achieved by two different one-pot multi-component
synthesis (one-pot three-component and one-pot four component synthesis). Mono and
dialkylation of 6 under different conditions gave compounds 7–11. The hydrazine 12
produced from reaction of 9 with N2H4 was subjected to reactions with some aromatic
aldehydes, ethyl acetoacetate, acetyl acetone, ethyl cyanoacetate and triethyl orthoformate
to give 13–17, respectively. Compound 12 upon reaction with CS2, nitrous acid, benzoin,
chloroacetone and phenacyl bromide gave 18,20,21,22. Alkylation of 18 with ethyl iodide,
ethyl chloroacetate and phenacyl bromide gave 19a–c. The antibacterial and antifungal
activities of selected derivatives were evaluated.

The synthesis of 3-methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydropyrazolo[5,4-b]
pyrimidino[5,4-e]pyridine-5-one (6) was achieved by two different one-pot multi-component
synthesis (one-pot three-component and one-pot four component synthesis). Mono and
dialkylation of 6 under different conditions gave compounds 7–11. The hydrazine 12
produced from reaction of 9 with N2H4 was subjected to reactions with some aromatic
aldehydes, ethyl acetoacetate, acetyl acetone, ethyl cyanoacetate and triethyl orthoformate
to give 13–17, respectively. Compound 12 upon reaction with CS2, nitrous acid, benzoin,
chloroacetone and phenacyl bromide gave 18,20,21,22. Alkylation of 18 with ethyl iodide,
ethyl chloroacetate and phenacyl bromide gave 19a–c. The antibacterial and antifungal
activities of selected derivatives were evaluated.