Friedel-Crafts Chemistry. Part 53. Divergent and Diversity-Oriented Synthesis of Condensed Indole Scaffolds via Friedel-Crafts Ring Closure Approach

A series of indole-fused medium-sized N-heterocyclic systems 10a-h were prepared from laboratory-synthesized indole-based esters 9a-h via intramolecular Friedel-Crafts cyclizations induced by both trifluoromethanesulfonic acid and AlCl3/CH3NO2 catalysts under suitable conditions. The synthetic seque...

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Published inAustralian journal of chemistry Vol. 72; no. 4; pp. 276 - 287
Main Authors Abd El-Aal, Hassan A. K., Khalaf, Ali A.
Format Journal Article
LanguageEnglish
Published CLAYTON Csiro Publishing 01.01.2019
CSIRO
Subjects
Acids
Alkylation
Aluminum chloride
Amides
Amines
Carbonyls
Carboxylic acids
Chemical synthesis
Chemistry
Chemistry, Multidisciplinary
Chloride
Esters
Friedel-Crafts reaction
Physical Sciences
Precursors
Science & Technology
Triflic acid
CYCLIZATIONS
CATALYZED REACTIONS
DERIVATIVES
ALKYLATION
CONSTRUCTION
AZEPINOINDOLE
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Summary:A series of indole-fused medium-sized N-heterocyclic systems 10a-h were prepared from laboratory-synthesized indole-based esters 9a-h via intramolecular Friedel-Crafts cyclizations induced by both trifluoromethanesulfonic acid and AlCl3/CH3NO2 catalysts under suitable conditions. The synthetic sequence to precursors 9a-h that started from simple N-methylindole-2-carboxylic acid involved conversion to aminoindoles 2a, b, reaction with ,-unsaturated acid chlorides to yield acyclic amides 5a-d, ring closure to tricyclic lactams 6a-d, and carbonyl reduction to respective pyrido and azepino tricyclic amines 7a-d, which finally underwent N-alkylations with - or -haloesters to produce the required ester precursors. The structures of synthesized compounds without stereochemical implications are established using both spectral and analytical data.
ISSN:0004-9425
1529-5036
1445-0038
DOI:10.1071/CH18537