A general procedure was developed to synthesize and characterize some new 1,2,4-triazole, 3-cyanopyridine, 3-aminothienoquinoline and 5,6,7,8-tetrahydroisoquinoline derivatives bearing a 4-aminosalicylic acid ester moiety as substructure. Some of them were further modified to give new derivatives. This work allowed the preparation of 18 new compounds obtained in good yields and under simple experimental conditions. These compounds were evaluated for their antimicrobial activity against four strains of bacteria and two fungal species.