A series of new pyrazolo[1,5-a]pyrimidine derivatives has been synthesized by using 7-hydrazinyl-5-methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile 1 and 7-amino-5-methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile 2 as precursors. The pyrazolo[3,4-d] pyrimidines 3a-b have been synthesized by a three-step reaction starting with 1. Compound 1 was utilized for the synthesis of dioxopyrrolidindolinylamio-pyrazolo-pyrimidines 4a-b, and dioxoisoindolin-pyrazolo-pyrimidines 4c-d. Also, compounds 4a-d were synthesized using deep eutectic solvents (DES). This method using DES provides several advantages such as benign environment, high yield, scalable and simple work-up procedure. Similarly, the cyclocondensation of 2 with α-acetylγ-butyrolactone afforded pyrazolo-pyrido-pyrimidine 5 and dihydrofuro-pyrido-pyrazolo-pyrimidine 6. All synthesized compounds were screened for antimicrobial activity.

A novel synthon 6-amino-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazolo[3,4-b] pyridine-5-carbaldehyde 4 was synthesized by multistep process. Then Friedlander condensation of this synthon with reactive methylenes was performed to achieve interesting tricyclic 6a-b, tetracyclic 6d and pentacyclic 6c N-heterocycles in excellent yield. The absorption and emission spectra of compounds 1-4 and 6 were measured and observed that the absorption and emission depends on the substituent at C-6 and C-7 position of pyridine ring in naphthyridines skeleton 6.