[Research on nitrogen heterocyclic compounds. XI. - New synthesis of 3H-benz(e)indole and its derivatives].

Glutaconic esters bearing a 2-naphthylamino moiety and a carbethoxy group at the 4-position underwent thermal decomposition to give 1-carbethoxy-3H-benz[e]indole derivatives. Alkaline hydrolysis of 1-carbethoxy-3H-benz[e]indoles gave the corresponding 3H-benz[e]indoles by loss of the carboxylic group. By this method were synthesized the known 3H-benz[e5indole and the 7-methoxy-3H-benz[e]indole. Glutaconic esters used in this procedure were prepared by condensation of ethyl propiolate with the appropriate 2-naphthylaminomalonate ethyl ester in the presence of a catalytic amount of sodium ethylate.