Synthesis and antifungal activity of some new quinazoline and benzoxazinone derivatives

The hitherto unknown 2-isopropyl-6,8-dibromo-4H-3,1-benzoxazin-4-one (2) wa s subjected to condensation with either primary or secondary amines affordi ng the benzamide derivatives (3-7), while with alcohols in presence of the base, corresponding esters were obtained (8 and 9). Acylation of the hydraz ide (12) or its cyclized form (13) gave (14-17). The quinazolinone derivati ve (18) was obtained either when (12) was reacted with nitrous acid or via fusion of (2) with ammonium acetate. The thione (20) which was obtained via reaction of (18) with Lawesson's reagent, was subjected to either alkylati on yielding (21-25) or desulphurization with primary amines affording (26 a nd 27). Treatment of (18) as well as (20) with a chlorinating agent provide d (29, 30) and (28, 29) mixtures, respectively. Ten of our compounds were e xamined against Sclerotium cepivorum as well as Botrytis allii on PDA media . These compounds showed a significant reduction of mycelial growth and scl eratia number of these fungi which cause the white rot and neck rot disease s of onion.