21000-00-0Relevant articles and documents
Electrophylic Substitution in Indoles. Part 12. Kinetic Studies of the Rearrangement of 3,3-Disubstituted Indolenines to 2,3-Disubstituted Indoles
Jackson, Anthony H.,Lynch, Patrick P.
, p. 1215 - 1220 (2007/10/02)
The rearrangements of 3-alkyl-3-methylindolenine salts to the corresponding 2-alkyl-3-methylindoles have been studied over a range of temperatures by u.v. methods in isopropyl alcohol containing hydrochloric acid.The relativ migratory aptitudes of the various alkyl groups were as follows: Me, 1; Et, 14; Pri, 120; allyl, 400; p-nitrobenzyl, 188; benzyl, 1520.Attempts to prepare the analogous p-methylbenzyl and p-methoxybenzyl-3-methylindolenines by alkylation of the 3-methylindole Grignard reagent gave only the 2-benzylindoles owing to the much higher migratory aptitude of the methylbenzyl and p-methoxybenzyl groups.Spiro hydrochloride rearranged to tetrahydrocarbazole at ca. 7400 times the rate of rearrangement of 3,3-dimethylindolenine hydrochloride to 3,3-dimethylindole.Thermodynamic parameters for the various reactions were determined in view of their relevance to the mechanism of electrophylic substitution in 3-substituted indoles.
