Synthesis of 1,4-benzodiazepin-3-ones and 1,5-benzodiazocin-4-ones by addition of Grignard reagents to derivatives of o-aminobenzonitrile

Addition of organometallics to N-(alpha-haloacyl)-o-aminobenzonitrile resulted in the formation of 2,5-disubstituted 1,4-benzodiazepin-3-ones, whereas N-(beta-haloacyl)-o-aminobenzonitrile gave 2,6-disubstituted 1,5-benzodiazocin-4-ones under similar conditions. Initial cylization of N-(beta-haloacyl)-o-aminobenzonitrile to obtain the corresponding lactam (e. g. alpha,alpha-dimethyl-N-(2-cyanophenyl)-beta-lactam) increased the yield of 1,5-benzodiazocin-4-ones significantly. Somewhat surprisingly, addition of lithium reagents to N-(beta-haloacyl)-o-aminobenzonitrile gave 4,4-disubstituted quinazolines via Grob fragmentation.