THE KEY compound 2-cyano-N'-(2,3-dihydronaphthalen-4(1H)- …..ylidene) acetohydrazide (1) was allowed to react with different aryl diazonium salts and different aldehydes to give the corresponding hydrazone (2a-d) and arylidene derivatives (3a-d). The arylidene derivatives (3a-d) were cyclized with malononitrile, ethylcyanoacetate and/or hydrazine hydrate to give the corresponding derivatives (4, 5 and 6). Moreover, compound 1 was condensed with different substituted isothiocyanates in the presence of chloroacetone, phenacyl bromide and/or ethylbromoacetate to give the thiazole derivatives (8-10). Compound 10 was coupled with various aryl diazonium salts to get the corresponding 4-oxothiazolidine compounds (11a,b). Furthermore, compound 1 was treated with carbon disulfide in the presence of hydrochloric acid, ethylbromoacetate and dimethyl sulfate to give the mercapto derivatives (12-14). Amino thiazole derivatives (16 and 17) were obtained by cyclization of compound 1 with phenyl isothiocyanate or cyclohexanone in presence of sulfur. These newly synthesized compounds were evaluated as antimicrobial and antiviral activity.