Benzodiazepines. IV. A New Synthesis of 1-Diethylaminoethyl-substituted 1, 4-Benzodiazepin-2-ones

A new synthesis of 1-(2-diethylaminoethyl)-substituted 1, 4-benzodiazepin-2-ones by ring enlargement of the corresponding 2-aminomethylindole derivatives is reported. A number of related compounds leading to these compounds were synthesized. Attempted chlorination of 5-chloro-1-(2-diethylaminoethyl)-3-(o-fluorophenyl) indole-2-carboxylic acid (VI) with thionyl chloride yielded 8-chloro-3, 4-dihydro-2-ethyl-10-(o-fluorophenyl)-pyrazino [1, 2-a] indol-1 (2H)-one (VII). Chlorination of 5-chloro-3-phenylindole-2-carboxylic acid derivative (VIII) with thionyl chloride gave two products, the expected acid chloride (XVI) and the dimer (XVII).