Reactions of condensed N-heteroaromatic molecules. Part I. Alkylation by thallium(I) ethoxide

Thallium(I) derivatives of carbazole, phenothiazine, and (to a lesser extent) dibenz[b,f]azepine (iminostilbene) may be readily alkylated by reactions with n-alkyl iodides and bromides under extremely mild conditions. 10,11-Dihydrodibenz[b,f]azepine (iminobibenzyl) is essentially unreactive and this, together with the complete inactivity of secondary alkyl halides, is indicative of serious steric constraints on the transition states for the alkylations via thallium(I) derivatives. The method is particularly valuable for alkylation of carbazoles having base-sensitive carbonyl and vinyl ring substituents.