Benzodiazepines. VII. Pyrazino [1, 2-α] indole-1 (2H)-ones and Their Conversion to 2, 3-Dihydro-1H-1, 4-benzodiazepines

抄録

A new synthetic route for the preparation of 2, 3-dihydro-1H-1, 4-benzodiazepines (6) is described. It consists of performing successively N-cyanomethylation of ethyl indole-2-carboxylates (1), reduction of cyano group, oxidation of 1-aminoethylindole derivatives (3 or 4) and finally hydrolysis of 2, 3-piperazinediones (5). In an alternative synthesis of the key intermediate 4a, intramolecular alkylation of N-(2-chloroethyl) indole-2-carboxamide (11) gave a mixture of 4a and 2-oxazolinylindole (12).