Synthesis and biological activity of some new benzophenothiazines

Abstract

Condensation of carboxylic acids with thiosemicarbazide in presence of conc. H₂SO₄ gives 2-amino-5-aralkyl-1,3,4-thiadiazoles <b>1</b> which on diazotization afford 5-aralkyl-1,3,4-

thiadiazolyl-2-diazonium chlorides <b>2</b>. Reaction of <b>2</b> with cold solution of β-naphthol in dilute NaOH furnishes α-(2-diazo-5-aralkyl-1,3,4-thiadiazolyl)-β-sodionaphthoxides <b>3</b> which on

acidification with conc. HCl gives α-(2-diazo-5-aralkyl-1,3,4-thiadiazolyl)-β-naphthols <b>4</b>. Reaction of <b>4</b> with <i>p</i>-anisidine gives α-(2-diazo-5-aralkyl-1,3, 4-thiadiazolyl)-β-(<i>p</i>-anisidino) naphthalenes <b>5</b>. Fusion of 5 with sulphur in presence of iodine results in 1-(2'-diazo-5' -aralkyl-1',3',4' -thiadiazolyl)-6-methoxy benzophenothiazines <b>6</b> in yields varying from 48% to 59%. The new compounds <b>6</b> have been screened for their antiviral and antifungal activities.