Synthesis and biological activity of some new benzophenothiazines

Condensation of carboxylic acids with thiosemicarbazide mi presence of cone. H2SO4 gives 2-amino-5-aralkyl-1,3,4-thiadiazoles 1 which on diazotization afford 5-aralkyl-1,3,4-thiadiazolyl-2-diazonium chlorides 2. Reaction of 2 with cold solution of beta-naphthol in dilute NaOH furnishes alpha-(2-diazo-5-aralkyl-1,3,4-thiadiazolyl)-beta-sodionaphthoxides 3 which on acidification with conc. HCl gives alpha-(2-diazo-5-aralkyl-1,3,4-thiadiazolyl)-beta-naphthols 4. Reaction of 4 with p-anisidine gives alpha-(2-diazo-5-aralkyl-1,3,4-thiadiazolyl)-beta-(p-anisidino) naphthalenes 5. Fusion of 5 with sulphur in presence of iodine results in 1-(2'-diazo-5'-aralkyl-1',3',4'-thiadiazolyl)-6-methoxy benzophenothiazines 6 in yields varying from 48% to 59%. The new compounds 6 have been screened for their antiviral and antifungal activities.