3-Hydroxy- and 3-alkoxy-2-sulfanylquinazolin-4(3H)-ones: synthesis and reactions with alkylating and acylating agents

Reactions of methyl 2-isothiocyanatobenzoate with hydroxylamine and alkoxyamines afforded earlier unknown 3-hydroxy-2-sulfanylquinazolin-4(3H)-one (1a) and 3-alkoxy-2-sulfanylquinazolin-4(3H)-ones (1b, c). Base-catalyzed reactions of compound 1a with alkyl halides were not regioselective, yielding O, S-dialkylation products. In the presence of acetic acid and sodium acetate, compound 1a was alkylated only at the S atom to give 2-alkylsulfanyl-3-hydroxyquinazolin-4(3H)-ones. Selective O-acylation of compound 1a at position 3 yielded 3-acyloxy-2-sulfanylquinazolin-4(3H)-ones.