Novel tricyclic thienopyrimidines (3, 5, 6, 9, 11, 12) and triazole fused tetracyclic thienopyrimidines (4a-c, 10a-c) were synthesized from precursors 2-amino-6-methyl-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile 1 and 2-amino-7-oxo-4,5,6,7-tetrahydro-1-benzothio-phene-3-carbonitrile 7 respectively. The corresponding precursors were prepared by employing the Gewald reaction. The structures of newly synthesized compounds were characterized by spectral and analytical data. All the compounds were screened for their biological activities. Some of the compounds displayed promising antibacterial and antifungal activities.

A new ammonium acetate-assisted, convenient and efficient procedure for the synthesis of arylidene derivatives of thiazolopyrimidine is described. The main advantages of this protocol is that it is economical, short reaction time, commonly available chemicals, and ease of isolation of products. In addition, a new series of thiazole-fused pyrimidines were synthesized and hydrolysis of one of its arylidene derivative studied. All the compounds were characterized by analytical and spectroscopic methods. Further, the structure of hydrolyzed product and two other compounds were confirmed by X-ray crystal structure analysis. The crystal structures are stabilized by intermolecular C-H...O, C-H...N, C-H... 𝜋 and 𝜋 ...𝜋 weak interactions. The anti-microbial screening was done on the compounds in order to test their anti-bacterial and anti-fungal activities.