Quinazolines and 1,4‐benzodiazepines. LXI. Syntheses of 7‐Acetyl‐1,4‐benzodiazepines

Methods for the synthesis of the biologically active 7‐acetyl‐1,3‐dihydro‐5‐phenyl‐2 H ‐1,4‐benzodiazepin‐2‐one ( 6 ) are described. This includes two new methods for the preparation of 5‐acetyl‐2‐aminobenzophenone ( 4 ). The crucial steps in these syntheses involve, respectively, the oxidation of an ethyl group to an acetyl group with permanganate or ceric ions ( 2 → 3; 5 → 6 ), the selective reaction of methyl lithium with the cyano group of 7‐cyano‐1,3‐dihydro‐5‐phenyl‐2 H ‐1,4‐benzodiazepin‐2‐one ( 8 ) and the efficient condensation of benzyl cyanide with the ethylene ketal of p ‐nitroacetophenone to form the anthranil 11 .