Formation of 4-(het)aryl-3H-1,5-benzodiazepine-2-carboxylates from (het)aroylpyruvate esters and o-phenylenediamine

Esters of (het)aroylpyruvic acids can react with o-phenylenediamine, leading to the formation of (Z)-3-(2-(het)aryl-2-oxoethylidene)-3,4-dihydroquinoxalin-2(1H)-ones and 4-(het)aryl-3H-1,5-benzodiazepine-2-carboxylates. The obtained product ratio depends on the electronic effects due to substituents in the (het)aroyl moiety of (het)aroylpyruvate esters and the reaction conditions. The highest ratio of quinoxalinones relevant for medicinal chemistry was observed when using (het)aroylpyruvate esters without substituents that would cause a negative mesomeric effect in the (het)aroyl moiety, as well as when performing the reactions in acetic acid.

Automated summary

This passage describes the formation of products from the reaction between (het)aroylpyruvate esters and o-phenylenediamine, and the relationship between the product ratio and the electronic effects of substituents in the (het)aroyl moiety and the reaction conditions.