Premium
Alkylation of 5‐ and 6‐Methylindolo[2,3‐ b ]quinoxalines: Revised Structures of the N , N′ ‐Dimethylated Salts
Author(s) -
Helissey Philippe,
DesbèneFinck Stéphanie,
GiorgiRenault Sylviane
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400386
Subject(s) - chemistry , alkylation , quinoxaline , two dimensional nuclear magnetic resonance spectroscopy , stereochemistry , diamine , nuclear magnetic resonance spectroscopy , structural isomer , organic chemistry , medicinal chemistry , catalysis
N , N′ ‐Dialkylation of indolo[2,3‐ b ]quinoxaline could theoretically furnish three isomers, that is, salts dialkylated at the 5,6‐, the 6,11‐, and the 5,11‐positions. By using the 2,3‐dimethylated derivatives as models, the regioisomeric salts were selectively synthesized either by alkylation of the tetracycle or by cyclization of 1‐methylisatin with N ,4,5‐trimethylbenzene‐1,2‐diamine. The structure of the N , N′ ‐dimethyl salts were unambiguously determined by NMR correlation sequences ( 1 H‐ 1 H NOESY, 1 H‐ 13 C HMQC, and 1 H‐ 13 C HMBC). The results of these studies show that the previous findings from the dialkylation of indoloquinoxaline need revision. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)