Ring closure reactions of methyl N-(haloacetyl)anthranilates with ammonia

In the presence of ammonia, methyl N-(bromoacetyl)anthranilate ( 4 ) is cyclized into 3H-1,4-benzodiaze-pine-2,5(1H,4H)-dione ( 1 ). However, when 4 is replaced with methyl N-(chloroacetyl)anthranilate ( 6 ), the only heterocyclic product formed in the reaction is 2-(chloromethyl)quinazoline-4(3H)-one ( 7 ). Under analogous conditions, 3-haloacetamidocrotonates (9, 10) do not yield any heterocyclic products and no 1,4-diazepines can be obtained.