Synthesis of Benzoxazolylthiomethyl and Benzthiazolylthiomethyl Quinazolin-4(3 h)-ones

Article abstract of DOI:10.1080/10426507.2015.1025905

o-Aminophenol (1a, X = O) or o-aminothiophenol (1b, X = S) was reacted with carbon disulfide in ethanol containing KOH under reflux to obtain 2-mercaptobenzoxazole (2a, X = O) and 2-mercaptobenzthiazole (2b, X = S), respectively. Condensation of 2a and 2b each with chloroacetic acid gave 2-(benzoxazol-2-ylthio)acetic acid (3a, X = O) and 2-(benzthiazol-2-ylthio)acetic acid (3b, X = S) respectively which with anthranilamide gave 2-((benzoxal-2-ylthio)methyl) quinazolin-4(3H)-one (5a, X = O) and 2-((benzthiazol-2-ylthio)methyl)quinazolin-4(3H)-one (5b, X = S) respectively. The products 5a,b could be prepared in three other routes involving the general sequences 6→2→5, 6→7→5 and 8→9→5.