Synthesis and Antimicrobial Activity of Tricyclic Quinazolinethiones

Deoxyvasicine thione (III) and mackinazoline thione (6,7,8,9-tetrahydro-11H-pyrido[2,1-b]quinazoline-11-thione, IV) were synthesized and condensed with aromatic and heterocyclic aldehydes at the alpha-methylene [CH2-3 (III) or CH2-6 (IV)]. Either 3- and 6-arylidene derivatives (V - XIII) or 6-hydroxymethylaryl derivatives (XIV) were formed depending on the reaction conditions. Formylation of IV synthesized the 6-hydroxymethylidene derivative (XV). 6-Chloro-, -hydroseleno-, and -anilinomethylidenemackinazoline thiones (XVI - XIX) were also synthesized. The antimicrobial activity of the synthesized compounds against S. aureus, E. coli, Bacillus cereus, Candida albicans, and Pseudomonas aeruginosa was studied.