New Conditions for Synthesis of (±)-2-Monosubstituted and (±)-2,2-Disubstituted 2,3-Dihydro-4(1H)-quinazolinones from 2-Nitro- and 2-Aminobenzamide

An efficient synthesis of (+/-)-2-monosubstituted and (+/-)-2,2-disubstituted 2,3-dihydro-4(1H)-quinazolinones has been developed using a dissolving metal reduction-condensative cyclization strategy. Treatment of 2-nitrobenzamide and an aldehyde or ketone with iron powder in refluxing acetic acid affords high yields of the title compounds. More complex ring systems are available by incorporating additional reactive functionality c to the carbonyl of the aldehyde or ketone substrate. The scope and limitations of the process along with optimized procedural details are presented. The same target molecules are also accessible by reaction of 2-aminobenzamide with aldehydes and ketones in refluxing acetic acid.