Heterocyclic Syntheses Through Electrophilic Ring Closure Reactions of ortho-Allylaniline Systems

Abstract

Amide derivatives of 2-allylanilines have been prepared by metallation of the amide derivatives of the corresponding 2-bromoanilines and subsequent reaction with an allylic halide. The electrophile -promoted cyclization of these compounds has been investigated. The free allylanilines readily undergo aminomercuration to form unstable mercury derivatives of tetrahydroquinolines but the corresponding amide derivatives do not cyclize. Instead, oxymercuration of the double bond occurs. The allylanilines react with iodine to yield 3-iodo-1,2,3,4-tetrahydroquinolines. The anion of 2,2,2-trifluoro-N-[4-hydroxymethyl-2-(3-methylbut-2-enyl)phenyl] acetamide reacts with iodine to give a 2,3-dihydroindole. These iodinated compounds can be further cyclized with base to form 7,7a-dihydro-1H-azirino[1,2-a] indoles. One of these aziridine systems was cleaved with hydrogen chloride to form a mixture of chlorinated tetrahydroquinoline and dihydroindole analogous to the iodo systems.